NRMJ_10_4_416-436

Introduction

The appearance and isolation of multidrug resistant (MDR) microorganisms have become a serious health problem, attributed to misuse and ingestion of unnecessary prolonged doses of antibiotics (Wang et al., 2023). These have clearly shown that there is a need to continue research to find out other innovative antimicrobial agents to inhibit MDR, which may include plant extracts, phages, NPs, to be used as a therapy, either singly or in combination with antibiotics (El-Gazzar and Enan, 2020; Wang et al., 2023; Enan et al., 2026). The resistance of bacteria to antibiotics is due to existence of MDR genes, which have existed through mutations in the bacterial genomes, modification of specific site(s) receptors, loss of cell membrane permeability, development of efflux pumps, and secretion of target protective enzymes (Zhang and Cheng, 2022). Various strains of MDR bacteria are identified, mainly Staphylococcus aureus, Staph. saprophyticus, Streptococcus pyogenes, Klebsiella typhi, Citrobacter freundi, Escherichia coli, Pseudomonas aeroginosa, Proteus mirabilis, Proteus vulgaris, and Listeria monocytogenes (Ryan and Ray, 2004; Enan et al., 2026).

Many plant extracts have antimicrobial, and antioxidant potentials assigned to their contents of quinones, while their anticancer activities are attributed to the involvement of quinones, caffeic acid, other organic acids, phenols, tannins, flavone, catechol, hypertin, catechin, coumarin, allin, eugenol, terpenes, alkaloids, wafarin, artemisin, harmane, capsaicin, and others (Chassagne et al., 2021). These phyto-extracts are effective as food additives and food protectives and are used in Chinese medicine as therapy (Cowan, 1999). Clove and lemon are two promising plants that are used in food as spices and have broad antimicrobial activity. Extracts of these two plants are used in combination with antibiotics, where they have shown a synergism and more antimicrobial activity, compared to using either the plant extract or the antibiotic individually (Malla et al., 2022).

Nanoparticles (NPs) have shown pronounced antimicrobial activity against MDR, because of their small molecular sizes (> 100 nm), enabling them to cross the bacterial cell wall and the membrane easily causing rupture to the cell’s membranes, leakage of cell nutrients, and generation of reactive oxygen species (ROS), leading to cell death (El-Gazzar and Enan, 2020). Consequently, scientists try to find out novel therapies based on NPs (Ali et al., 2022). The biosynthesized NPs using plant metabolites are preferable than those chemically synthesized, as they are non-toxic and are produced in large amounts (Wang et al., 2017). NPs- conjugated antibiotics have displayed higher antimicrobial activity, as they can act in synergy and are used as carrier for the delivery of antibiotics.

The aim of this review is to show the recent innovative therapies that can be used to inhibit the MDR bacteria, mainly phyto-extracts and plant-based NPs, where their importance and necessity are provided.

Development of innovative antimicrobials other than the classical antibiotics

The first antibiotic detected by Alexander Flemming in 1940 was penicillin, which has been regarded to be an effective antibacterial agent and thus well used in medicinal treatment (Magalhaes et al., 2021). Later on, many antibiotics have been detected such as cephalosporins, chloramphenicol, tetracyclins, streptomycin, macrolides, glycoproteins, lipoglycoproteins, aminoglycosides, and antimicrobial proteins (Wang et al., 2023). These antibiotics are classified according to their origin, spectra of activity, modes of action, and structure (Wilson Lucas et al., 2023). It has been found that some antibiotics may inhibit cell wall synthesis of the bacteria, inhibit cell membrane synthesis, membrane function, nucleic acids replication, RNA transcription, and/or protein synthesis. Additionally, certain antibiotics may inhibit the cell metabolites production (Kapoor et al., 2017; Saber et al., 2022).

Since 1940s until now, these antibiotics have saved millions of people from dangerous infectious diseases. The misuse of these antibiotics by ingestion, prolonged doses, overdoses, and their use without prescription by the physicians, has led to the appearance of many MDR bacteria, resulting in a serious threat for human health (Wang et al., 2023). Thus, the existence of MDR in most countries has become a big problem to human health (Verma et al., 2021). This displays an urgent need to continue research to find out other innovative antimicrobials able to be inhibiting and/or killing the MDR. These innovative antimicrobials include those based on plant extracts (Enan et al., 2026), antimicrobial peptides (Sitohy et al., 2024), NPs, and phage therapy (El-Gazzar and Enan, 2020).

The search for novel therapies is mandatory because antibiotics enter the target cells through specific receptor site(s), where these receptors may become altered and modified, resulting in failure in entry of the antibiotics to the bacterial cells (Enan et al., 2026). Other mechanisms of antibiotic resistance in bacteria are recorded, including development of bacterial mutations, due to a sudden change in the bacterial genome in certain targets of either the bacterial nucleoid or their plasmids, reduction or loss of cell membrane permeability, development of efflux pumps leading to leakage of cell electrolytes, defect in metabolism as well as metabolic enhancement, secretion of target protective proteins, and community cooperative resistance that develop via transfer of antibiotic resistance genes within the bacterial community (Enan, 2005; Zhang and Cheng, 2022). Consequently, the search for novel antimicrobials such as plant extracts and NPs is needed, to be used either singly or in combination with antibiotics (El-Gazzar and Enan, 2020).

The commonly of isolated and identified MDR bacteria

Staphylococcus aureus: Staphylococcus aureus is found to cause wound and skin infections such as impetigo and cellulities (Boyce et al., 1997). The majority of Staph. aureus strains have resistance to the antibiotic methicillin and are thus called methicillin-resistant Staph. aureus (MRSA), which are responsible for several difficult-to-treat human infections. However, few strains are sensitive to such antibiotic and called methicillin-sensitive Staph. aureus (MSSA). Staph. aureus strains contain mecA gene(s) responsible for antibiotic resistance, whereas the sensitive strains have a dissociated or cured mecA gene. Meanwhile, the MRSA strains resist other β-lactam antibiotics, including didoxacillin, nafcillin, and oxacillin and also resist the action of cephalossporins. These MRSA strains cause numerous infections in hospital-stayed humans, nursing homes, and prisons (Janknegt, 1997). The antibiotic vancomycin and its structural glycopeptide teicoplanin are used to treat the MRSA strains. However, certain problems have appeared upon use of these antibiotics, as vancomycin may cause nephrotoxicity (kidney damage) and also specifically cause red man syndrome, while teicoplanin can provoke cross a reactive hypersensitivity. Few strains of MRSA resist vancomycin upon use at <10 µg/ml and are called vancomycin intermediate Staph. aureus (VISA) (Schentag et al., 1998; El-Didamony et al., 2016; Saber et al., 2022). On the other hand, those MRSA strains that resist the action of > 10 µg/ml vancomycin are called vancomycin resistant Staph. aureus (VRSA) (Simon et al., 2009).

Staphylococcus saprophyticus

Staphylococcus saprophyticus strains are isolated from urine of male and female patients suffering from urinary tract infections (UTIs), in addition to the more severe cases such as cystitis, endometrities, and pyeloneploritis. Most infections induced by Staph. saprophyticus are caused to the sexually active women, male homosexuals, and elderly men with urinary catheters and those suffering from prostatitis, urethritis, and epididymitis. Staph. saprophyticus is also found to resist the action of certain antibiotics due to acquiring several antibiotic gene(s) from the community (Tolaymat and Al-Jayousi,1991; Harbarth et al., 2002).

Streptococcus spp.

Streptococcus pneumoniae (pneumococcus): Streptococcus pneumoniae (S. pnemoniae) is isolated from nose swabs of patients suffering from sinusitis in children. It infects neonates and older people with chronic and immuno-compromised cases. S. pneumonia is a member of the family Streptococcaceae and can be found in the oral cavity thoroughly with S. mitis and S. oralis (Claverys et al., 2000). It also causes ear infections, UTIs, and meningitis in neonates (Edwards and Baker, 2005). S. pnemoniae is usually treated by penicillin G and other β-lactam antibiotics. Unfortunately, Vanderkooi et al. (2005) studied the isolation of pneumococci strains from blood samples taken from neonates suffering from certain diseases and few of them are resistant to β-lactam antibiotics, tetracyclins and fluorquinolones. S. pneumoniae causes partial hemolysis on blood agar with developing green zone due to the formation of oxidative metabolites by the reaction between hemoglobin with hydrogen peroxide, this is so-called α-hemolysis (Albrich et al., 2004).

Streptococcus pyogenes (S. pyogenes): According to Lancefield grouping of streptococci, S. pyogenes is classified as group A streptococci (GAS), causing complete hemolysis of hemoglobin on blood agar (β-hemolysis). The name pyogenes comes from the word pyogenic, which is associated with sepsis and puss formation (Edwards and Baker, 2005). GAS is isolated from upper pharynx swab and dental infections. It is also approved to cause scarlet fever, endocarditis, rheumatic fever, glomerulonephritis, and necrotizing fasciitis (Edwards and Baker, 2005).

Several strains of GAS are found to resist the action of the macrolide’s antibiotics along with other antibiotics. Their resistance to these antibiotics is due to genetic reasons, where certain genes encoding antibiotic resistance can be transmitted from the body community to S. pyogenes by conjugation. Rapid treatment of GAS infection is mandatory using fast diagnostic tests such agglutination test, C reactive protein (CRP), and antibiotic bioassay (Simon et al., 2009; Enan et al., 2016).

Common Gram negative Enterobacteriaceae

Klebsiella species: Klebsiella spp. are isolated from pus samples of patients infected with pnemoniae and neonates admitted to the intensive care units (ICU) suffering from UTIs. Their cells are Gram negative, catalase positive rods with rounded ends. The pathogenic species belong to K. pnemoniae, K. oxytoca, and K. granulomatis. Other emerging species include K. varicola and K. quaspinemoniae, which can cause soft tissue infections (Clegg and Sebghatti, 2002). As Klebsiella spp. have developed resistance to the action of several antibiotics including macrolides, lincosamides, penicillins, ketolides and quinolones, their treatment must start immediately after their identification using recent techniques such as viteck-2 protocol and antibiotic bioassay. It has been reported that the MDR Klebsiella spp. are encoded by gene(s) located in the cell plasmids with varying molecular masses (Palasubramaniam et al., 2005; Dong et al., 2022).

Citrobacter species: Citrobacter spp. are other members of the Family: Enterobacteriaceae. Their cells are Gram negative rods. They are isolated from many swab samples of sinusitis cases and are inhabitants of the intestines. They are reported to cause children meningitiss, septicemia, pneumonia in the immunocompromised patients. The most common pathogenic species are C. freundi and C. maloniticus (Brenner et al., 1999). Certain MDR strains of Cirobacter have been identified, which are resistant to ampicillin and cephalossporins as they contain the ampC genes in their genomes that encode for the antibiotic resistance ability (Wang et al., 2000).

Pseudomonas aeruginosa (P. aeruginosa): Pseudomonas strains are isolated from medical samples collected from patients suffering from pneumonia, nosocomial infections, UTIs, and blood stream infections such as otitis media, osteomyelitis, and otitis externa. It is an opportunistic pathogen and an important cause of nosocomial infections (Driscoll et al., 2007). Its infections are often associated with high morbidity and mortality rates compared to the other bacterial infections (Osmon et al., 2004; Oin et al., 2022). P. aeruginosa strains are selectively isolated on cetrimide agar (Oxoid), where it forms blue green coloration on this medium and appear to be Gram negative non-spore forming rods. Their infections are common in immunocompromised patients such as cystic fibrosis, bronchiectasis, neutropenia, burns, AIDS, organ transplant, and controlled diabetes mellitus. P. aeruginosa is of limited susceptibility to antibiotics (Harris et al., 1999). The wounds are a target of colonization by the opportunistic strains of P. aeruginosa (Lari and Alaghehbandan, 2000). P. aeruginosa bacterium shows resistance to different antibiotics. The resistance profiles are different among several strains. Their resistance is often attributed to different mechanisms such as modification of specific receptors site(s) and genetic reasons (Wright et al., 2009).

Proteus species: Proteus spp. are bacteria commonly inhabiting the environment, including polluted water, raw meat and poultry, soil, and gastrointestinal tract of human and animals. Both P. mirabilis and P. vulgaris are isolated from urine of patients suffering from UTIs and severe abscesses swabs. P. mirabilis is the commonly pathogenic species and is dominant in these cases. Proteus bacteria are Gram negative and catalase positive rods (Ryan and Ray, 2004). They are also isolated from swabs of nose(s) collected from patients suffering from nosocomial infections (Matsuyama et al., 2000). Several studies have shown and noted resistance of Proteus spp. to multiple antibiotics, including β-lactams, macrolides and lincosamides (Guentzel, 1996; Enan et al., 1996, 2026).

Escherichia coli (E. coli): Escherichia coli is a common inhabitant of human and animal intestine. It is a part of human natural microflora, but some strains can cause diarrhea if contaminated water or food are used in meal, as these bacteria commonly exist in the environment such as water and wind. E. coli strains are isolated from urine collected from patients with UTIs and are rarely isolated from pus of people having pneumonia. They are also isolated from nose swabs of nosocomial infections or pharyngitis cases (Vogel et al., 2004). E. coli bacteria are Gram-negative rods and are firstly detected by the German pediatrician Escherich in 1985 (Todar, 2007; Rahman et al., 2011).

Based on the O, H, and K antigens, over 700 serovars of E. coli have been identified (Todar, 2007). Several types of E. coli have been detected such as the enterotoxigenic E. coli, which are found in water and contaminated food and may cause watery diarrhea. Meanwhile, enteropathogenic E. coli that causes watery diarrhea in children can cause outbreaks in nurseries or day care centers. The entero-aggregative E. coli causes acute diarrhea without fever, while the entero-invasive E. coli strains originate from eating contaminated vegetables, hamburger, and under-cooked meat, and may cause bloody diarrhea, abdominal cramps, vomiting, fever and chillis. The entero-invasive and enterohemorrhagic strains are Shigella related or the so-called E. coli O157, which contain the gene encoding for the shiga-like toxin that is acquired from the community by conjugation (Holmes, 1998). Many strains of E. coli are MDR depending on the nature of each strain (Enan et al., 2013; Enan et al., 2026).

Plants having antibacterial activities

To find out safe antimicrobials, plants are recently used as potential solutions, as they produce secondary metabolites that could inhibit the microbial pathogens (Abolfazl et al., 2014). The plant’s secondary metabolites are by-products responsible for the specific odor, taste, and color of the plant tissues and are important for plant growth and development. Most of these metabolites such terpenoides, alkaloids, and phenolic compounds possess biological, antioxidant, and antiproliferative activities (Enan et al., 2018; Belcher et al., 2020).

The medicinal plants are highly biodiverse, and the most recent estimates have revealed the total number of these plants are approximately 374.000. These include the described vascular plant species (Monocots and Dicots), gymnosperms, ferns, and algae (Chassagne et al., 2021). Plants are used in medicine as agents for treating diseases across different civilizations and dated 2600 years before the common era (2600BCE). The Eberys papyrus is a well-preserved scroll detailing a variety of plants traditionally used for treatment of a wide range of diseases in the ancient Egypt (Abreu et al., 2012). Today, in many parts of the developing countries, many people continue to use the medicinal plants as primary sources of medicine. According to the Medicinal Plant Names Services (MPNS), 28187 plant species are recorded and approved as being used medicinally (Chassagne et al., 2021).

Phyto-extracts obtained from medicinal plants have demonstrated a pronounced antibacterial activity. These plants belong to different families such as: Lamiaceae, which includes Origanum vulgare, Thymus zygis, Rosmarinus officinalis, Thymus vulgaris, Clinopodium taxifolium, Clinopodium vulgaris, Mentha piperita, Stachys pubescens and Ocimum basilicum. Fabaceae family including many plants that contain bioactive metabolites such as Dichrostachys cinerea, Albizia gumiferer, Acacia kare, Albizia myllophylla, Glycyrrtitza triphylla, Coporifera reticulata, Glycyrhiza glabra, Calpurina aurea, Cuperyfera paupera and Copaifera publifora. Astracea family such as Tanacutum polycephalum, Xanthum strumarium, Echinups keberichu, Cota palestine, Mikania glomerata, Artemisia abyssinica, Matricuria chamamos, Rhanterium suaveolens, Lilogyne garipina and Achyrucline saureioides. The family Myrtaceae includes 37 species, 10 of them only have displayed antibacterial potentials such as Rhodomyrtus tomentosa, Eucalyptus camaldulensis, Syncarpia glomulifera, Corymbia torelliana, Myrtus communis, Syzygium cordatum, Melaleuca armillaris, Eugenia brevistyla, Eugenia catharinae, Eucalyptus globulus and Psidium guajava.

Also, the Anacardiaceae family contains many plants with antibacterial efficacy such a Anacardium occidentale, Schinus terebinthiofolia, Pistachia terebinthus, Mangifera indica and Pistachia lentiscus. Rubiaceae family involves some plant’s extracts containing quinine and other antimalarial alkaloids, including Pavetta lanceolate, Cephalanthus natalensis, and Sarcocephalus latifolius. In addition, Apiaceae family contains aromatic herbs and many other poisonous species such as Trachyspermum ammi, Coriandium sativum and Eryngium spp. (Chassagne et al., 2021). Moreover, many terrestrial non-vascular archigoniate have expressed bioactive properties. Certain aquatic plants and algae have demonstrated pronounced antibacterial activities and are used in many medicinal applications (Chassagne et al., 2021).

Phyto-extracts possessing antimicrobial activities

Plant extracts are used to treat several human infectious diseases worldwide. According to the literature, the majority of population all over the world depend on the natural traditional medicine (Vashist and Jindal, 2012). The potential of higher plants as a source of new drugs is still largely unexplored and only a small percentage of the plants have been investigated phytochemically (Kowalski and Kedzia, 2007). The phyto-extracts have been used as sources of therapeutic agents, either singly or in combination with antibiotics (Mahesh and Satish, 2008; Enan et al., 2026). Medicinal plants mentioned above are rich sources of antimicrobial agents against the different microorganisms; thus, they are used in certain therapies or as food additives for food conservation. They contain bio-active compounds that are mostly aromatic, heterocyclic, and conjugated with certain aliphatic moieties. It is possible that one plant contains more than one group of bio-active compounds. For instance, thyme has thymol and carvacrol, clove contains eugenol and isoeugenol, oregano has carvacrol and terpenoids, which are water soluble in some cases and with broad antimicrobial activity (Knobloch et al., 1989). The most important antimicrobial compounds existing within the plant extracts are quinone, flavone, organic acids, catechol, hypericin, terpenoids, alkaloids, warfarin, artemisin, berberine, harmane, and capsaicin (Silva and Junior, 2010).

The modes of action of most phyto-extracts include their ability to disintegrate the cytoplasmic membrane, destabilize the proton motive force, electron flow, active transport, and coagulate the cell content. It has been shown that these agents act on specific site(s) or receptors, which could be altered by several reasons. For instance, the essential oils are of hydrophobic nature and can allow the collisions of lipids from the bacterial cell structures and loss of cell permeability (Sikkema et al., 1994). Moreover, they act on cell membrane proteins and interact with their active transport functions (Conner and Benchat, 1984). Cowan (1999) study has revealed the various classes of bio-active phyto-extracts and their mechanisms of action as follows: Terpenoids induce membrane disruption; phenolics in general induce membrane deprivation, enzyme inactivation, membrane disruption, inhibition of transcription, adhesion binding, and metal ion complexation; alkaloids induce intercalation into cell wall and deoxyribonucleic acid (DNA); and lectins and polypeptides induce disulfide bridge formation.

Lemon and clove are two promising plants for human health

Lemon and clove are two promising plants for human health, as they contain various antioxidant and antimicrobial compounds as follows:

Lemon (Citrus limon)

Citrus limon is an evergreen tree that is cultivated in both sandy and clay soils. Lemon fruit, in addition to its uses in medicinal purposes, is used as a food ingredient with an attractive taste in human meals. C. limon belongs to family Rutaceae, Order Saphindales (Hindi and Chaabuck, 2013). Lemon juice provides considerable health benefits due to its high content of vitamin C, antioxidants, and citric acid that promotes skin health by supporting collagen, aiding in digestion, and help in preventing the formation of kidney stones by reducing the stone forming compounds. It also enhances iron absorption from food, supports cardiovascular health, helps in decreasing the blood cholesterol level, and lowers the body inflammation. In addition, lemon juice contains folic acid and potassium, which are beneficial for the body’s metabolism (Maruti et al., 2011). Lemon contains essential oils, mainly protopine and corydaline alkaloids, lactones, polyacetelene acyclic sesquiterpenes, hypericin and pseudohypericin compounds, which are effective against the bacterial pathogens (Maruti et al., 2011). Moreover, lemon fruit has been used in traditional Chinese medicine to improve the bronchial and asthmatic conditions (Kalpa et al., 2012). Lemon juice has shown an inhibitory activity against many bacterial strains namely: E coli, Acinetobacte spp., Staph. aureus, S. pyogenes P. aeruginosa, Candida albicans and other pathogenic strains (Hindi and Chaabuck, 2013). Lemon juice obtained from C. limon fruit and orange possesses good antimicrobial activities. Additionally, it is among the most studied natural antimicrobials used in food applications as a beneficial juice, additives to the various meals, and attractive and beneficial additive to the different salads. The lemon pickles are desired and attractive in the Egyptian meals (Corbo et al., 2008). There are several Citrus species of medicinally important values such as C. limon (lemon), C. aurantium (bitter orange), C. limetta (sweet lemon), C. jambhiri (rough lemon), and C. paradise (grape fruit) (Al-Ani et al., 2009; Kalpa et al., 2012).

The literature has shown that daily usage of lemon juice as food ingredient such as salad, which decreases the risk of microbial infections and decreases the release of ROS (Ravikumar et al., 2005), and it also decreases the risk of infection by Salmonella typhi (Hindi and Chaabuck, 2013). Dhanavade et al. (2021) study has revealed that the different alcoholic extracts of lemon peel provide antimicrobial activity against various bacterial strains, especially P. aeruginosa and S. typhimurium, compared to the aqueous extract, which did not express any antibacterial efficacy. A previous study reported by Dhanavade et al. (2021) has shown that lemon juice has inhibited various MDR bacteria through its ability to disrupt the membrane permeability. Meanwhile, the acids, other phenolic compounds, and flavonoids that exist in lemon juice have inhibited the MDR bacteria throughout hydrophobic interactions. Additionally, collisions have caused leakage of the cell electrolytes; thus, converting the bacterial cell into a de-energized dead cell (Malla et al., 2022). The previous study reported by Malla et al. (2022) has concluded that the resistance of Klebsiella spp. to the antibiotic carbapenem is attributed to carbapenems activity, which is correlated genetically to blaoxA-45 gene. However, lemon juice treated isolates have displayed a decreased activity of carbapenem, which has coincided with partial curing of the blaoxA-45 gene. Thus, the bacterial virulence has also decreased as lemon juice contains flavonoids such as hesperidin and naringin, which act as inhibitors of food borne pathogens through disruption their cell membranes, lowering the intracellular pH value, and inhibiting quorum sensing (QS) that attenuates the pathogenicity.

Clove (Syzgium aromaticum)

Due to the importance of the plant clove (Syzgium aromaticum) as a promising medicinal plant, many studies have discussed its importance as follows:

An overview on the clove and its systematic position: Dried flower buds of the Syzygium aromaticum (clove) tree are used as a spice in almost all the world. Clove has several synonyms such as Eugenia caryophyllata (Ahamad, 2024). The clove is a member of the family Myrtaceae. It is native to the Maluku islands of Indonesia (Ahamad, 2024). Myrtaceae family belongs to order: Mysrtrales, Class: Magnoliopsida, and Division: Spermatophyta (Kamble, 2024).

Nutritive benefits of clove flower buds extract: Clove flower buds extract contains minerals like manganese, which is important for functions of neuro-cells, calcium that is important for bone function, and iron which is a mandatory element in blood hemoglobin. It contains also magnesium, phosphorous, sulfur, sodium, zinc, and copper. Clove flower buds extract contains beneficial macromolecules, including soluble sugars, proteins, and fats, which are important for health. Additionally, this extract contains vitamin C and vitamin K that are human hygienic (Kaur et al., 2019). Clove flower buds extract is used as a food spice and gives foods an attractive flavor (Al-Qareer et al., 2006).

Bioactive compounds of clove flower buds extract: Clove flower buds extract includes quantities of essential oils (about 16% to 18%) in which eugenol, caryophyllene, and eugenol acetate are found as main constituents and are supposed to be responsible for its bioactivities (Haro-González et al., 2021). Besides the essential oils, clove buds also contain other phytochemicals such as saponins, flavonoids, phenolic acids, alkaloids, tannins, steroids, resins, and glycosides (Mostafa et al., 2023; Ahamad, 2024). The agroclimatic conditions in which cloves are grown, processed, and stored affect their composition. Carbohydrates, fixed oil, steam-volatile oil, resins, tannins, proteins, cellulose, pentosans, and mineral elements are all present in the dried clove buds. Approximately two thirds of the spice’s weights are made up of carbohydrates. Nutrients like proteins, minerals, and vitamins are also included in the dried dark and flower buds (Gülçin et al., 2012). The chemical constituents of clove include various volatile and non-volatile constituents. Cloves yield different types of volatile oils, where the production and quality of these oils vary considerably. The oil’s origin, season, raw material type and quality, harvest maturity, pre- and post-distillation treatments, and distillation techniques all affect its yield and composition. Eugenol is the main ingredient in all kinds of oils. The majority of the distinctive clove aroma are caused by eugenol, which makes up 72–90% of the produced essential oils (Kamatou et al., 2012; David et al., 2026). Clove bud’s fresh extracts contain 15–20% essential oils, which consist of eugenol (70–85%), eugenyl acetate (10-15%), and β-caryophyllene (5–12%). Methyl amyl ketone, methyl salicylate, α-and β-humulene, benzaldehyde, p-ylangene, kaempferol, gallotannic acid, crategolic acid, and chavicol are other components of the oil. The distinctive aromatic smell of cloves is caused by minor constituents such as methyl amyl ketone and methyl salicylate (Abdulrasheed, 2018; Haro-Gonzalez, 2021). The major components of clove (> 90%) include eugenol (70%), eugenyl acetate (5-15%), β-caryophyllene (5-12%), whereas the minor components (less than 10%) include caryophyllene oxide, -copaene, -cubebene, chavicol, cadienene, diethyl phthalate, and 2-noanone (Tariq et al., 2025).

Antimicrobial potential of active compounds of clove flower buds extract: Clove flower buds extracts have shown promising antimicrobial, antiviral, anticancer, antiseptic, antispasmodic, and anti-inflammatory activities. Therefore, it is used in treatment of tooth infections and dental pain. In traditional Chinese medicine, clove flower extracts are used as stimulant, carminative and stomachic, and intestinal and liver stimulant, in addition to their use to treat nausea, vomiting, and flatulence (Sarker and Islam, 2022). Clove flower extracts are also used in treatment of malaria, tuberculosis, and cholera in tropical Asia (Ahmed et al., 2021b; Ahmad, 2024).

Eugenol (4-allyl-2-methoxyphenol) is the most important bioactive compound of the clove flower extracts (Zhai et al., 2022). The antimicrobial activity of eugenol is assigned to its hydroxyl group that can integrates the bacterial membranes and disrupts the membrane integrity, leading to partial loss of membrane permeability, followed by cell death (Pilong et al., 2023). Eugenol is mostly of lipophilic nature and may cause oxidative damage that increases the ROS such as superoxide dismutase, which can also cause depolarization and ATP leakage (Khwaza and Aderibigbe, 2025).

Other promising applications of clove essential oils are tested to improve the soft cheese safety (Ahmed et al., 2021a). When combined with shirazi-thyme and cinnamon essential oil, clove essential oils have displayed synergistic antibacterial activities against growth of the pathogenic and the spoilage bacteria in the refrigerated chicken breast meat, such as E.coli, Staph. aureus, and P. fluorescens (Chaichi et al., 2021). Eugenyl acetate is also used as food additive because of its broad antibacterial, insecticidal, antioxidant, and anticancer activities (Haro-González et al., 2021). Clove essential oils have shown an antibiofilm activity that is promising in food industry. Nisin bacteriocin has been used for several years as a food protective, where the nisin-essential clove oil combinations have shown a pronounced inhibitory activity against biofilms derived from several pathogenic bacteria and expressed an important role as food preservatives (David et al., 2026).

It has been demonstrated that MDR bacteria resist the action of antibiotics due to the secretion of enzymes such as β-lactamase, however, eugenol inhibits the β-lactamase activity and thus can inhibit these MDR bacteria (Muhammad and Shoge, 2023). One of the important reasons of bacterial resistance to the antibiotics is the presence of resistance genes within bacterial genome, either in the chromosome or the plasmids, such as mecA and mecB genes responsible for resistance of Staph. aureus to methicillin. Eugenol is able to decrease the expression of these genes and can dissociate these antibiotic resistance genes (Rao et al., 2023; Lawani et al., 2024; Tariq et al., 2025).

Applications of clove flower buds extract: Clove is one of the most valuable spices that has been used as food preservative and for many medicinal purposes, mainly due to its antioxidant and antimicrobial activities. Nowadays, many reports have confirmed their antibacterial, antifungal, antiviral, and anticarcinogenic properties (Cortés-Rojas et al., 2014; Al-Qareer et al., 2006). Clove contains appreciable amounts of volatile oils (used for flavoring foods and pharmaceuticals), which are mainly confined to the aerial parts of the plant. Clove is used in a variety of ways, including medicine and cooking. As a useful culinary spice, clove can be used to flavor onions, tomatoes, salads, herbal drinks, and soups. Meat items, cookies, chewing gum, pickles, chocolates, soft drinks, puddings, sandwiches, pastries, and sweets are all flavored with clove. Pharmaceuticals, soaps, toothpastes, and perfumes can benefit from the use of volatile oils (Hu et al., 2018). Clove buds extract can be used as a food additive. The shelf-life and frying stability of the encapsulated and un-encapsulated eugenol-rich clove extracts have been tested in soybean oil. Clove flower buds extract is used as a dental analgesic and a constituent of cosmetics, because of its antiseptic and antimicrobial activities (Cortés-Rojas et al., 2014).

Mechanisms of action of clove flower buds extract: Clove phytochemicals function mechanistically in a hierarchical cascade where the main initiating action is membrane disruption. The clove essential oil’s chemical structure includes (–OH) groups at meta and ortho positions that interact with the cytoplasmic membrane, disrupt phospholipids, and prevent the protein translocation, phosphorylation, electron transport, and other enzymatic activities (Shahbazi, 2019). Rapid loss of membrane potential, K+/ATP efflux, and collapse of the proton-motile force (PMF) are caused by the clove’s lipophilic components, particularly eugenol, partitioning into and disordering the phospholipid bilayer. Secondary intracellular effects, including reduced electron transport and tricarboxylic acid cycle (TCA-cycle) enzymes activity, increased electron leakage with ROS generation, macromolecular damage (i.e., lipid peroxidation, protein oxidation, DNA strand injury), and functional inhibition of energy-dependent efflux, become possible by this primary membrane failure. Incubation of Staph. aureus with eugenol has led to an increased production of ROS and hyperactivation of several antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, and catalase, ultimately resulting in an oxidative stress-induced cell death (Bai et al., 2023). Moreover, eugenol can alter the DNA conformation by forming eugenol-DNA complex and disrupts the DNA synthesis, preventing bacterial replication. All these processes result in cell membrane lysis followed by cell death (Tariq et al., 2025). The single-layered peptidoglycan component of the Gram-positive bacterial cell wall provides a minimal resistance, making these bacteria susceptible to essential oils. Gram-negative bacteria, on the other hand, have an outer membrane made of lipopolysaccharides, peptidoglycan, and other proteins. This complex structure prevents lipophilic substances such as eugenol from diffusion (Zhao et al., 2021).

Clove buds extract affects the bacterial virulence, where it downregulates the expression of the virulence genes responsible for the pathogenicity of the bacteria. It is found that clove essential oil has remarkably inhibited the expression of both sea genes that encodes staphylococcal enterotoxin A and hla genes that encodes alpha-hemolysin formation, representing the major virulence factors produced by most Staph. aureus strains. The obtained results have also displayed that clove’s essential oil can inhibit the expression of agr system (agrA and agrC genes), which in turn will inhibit the formation of biofilm by Staph. aureus (Li et al., 2022). Several studies on clove and eugenol have reported downregulation of the QS-regulated genes and reduced biofilm formation at sub-inhibitory concentrations (Ali et al., 2022; Tariq et al., 2025). Clove extract has been discovered to suppress QS-controlled gene expression in P. aeruginosa and Chromobacterium violaceum (Zhou et al., 2013). Eugenol treatment has resulted in downregulation of the expression of flagellar gene (flhD) responsible for motility, biofilm formation genes (bsmA and bsmB), fimbrial gene for adhesion (fimC), and QS regulatory gene (swrR) in Serratia marcescens strains (Fekrirad et al., 2020). It has also downregulated the critical biofilm-associated gene dnaK, bacterial adhesion-related genes such as flaA, fliP, flgE, and motA, a transcriptional activation gene prfA, and QS related genes in Listeria monocytogenes (Hu et al., 2018).

Moreover, clove oil has dramatically dissociated the virulence genes gtfB and gtfD, with fold changes of 0.178 and 0.454, respectively compared to licorice extract. These results have been obtained from a Real-time polymerase chain reaction (RT-PCR) study that has evaluated the impact of clove flower extract and licorice on gene expression in S. mutans, a major agent in dental caries (Al-Amili and Al-Jobori, 2025). In Campylobacter jejuni, clove essential oil has suppressed the expression of several virulence-associated components. RT-PCR results have indicated that at least two virulence-associated genes are downregulated when clove essential oil is present. Both flhB, which encodes for a flagellar biosynthesis protein and glucose 4-epimerase (galE) that is involved in the production of lipo-oligosaccharides, become downregulated by almost seven times. A substantial outer membrane protein gene called porA has shown a three-fold downregulation (Kovács et al., 2016). In a previous study conducted on UT infections in Egypt, Pseudomonas sp. with antibiotic-resistant genes like blaTEM and blaSHV, which has been tested against clove ethanolic extract, has demonstrated an inhibition zone diameter of 23 mm with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) ranging from 10 to 121.25 mg/ml, and 20 to 30 mg/ml, respectively, suggesting clove as a possible effective treatment strategy for MDR bacteria (Ahmed et al., 2021b).

Biofilm formation is a major virulence factor in MDR bacteria, so new anti-biofilm substances are required because biofilms are increasingly more resistant to the traditional cleaning products, disinfectants, and antibiotics. Biofilms increase the resistance of bacteria to antibiotics and the host immune system, thereby increasing their capacity to remain in the infected host. Persistent polysaccharide production is associated with the survival of E. coli and Salmonella biofilms after a quaternary ammonium chloride sanitization (Milho et al., 2019). Biofilm detachment and contamination during food manufacturing may cause food spoilage and perhaps cause foodborne illnesses when the infected food is ingested (Badi et al., 2022). Consequently, there are extensive researches on the potential of plant essential oils to prevent the formation of biofilms and develop novel antibiofilm agents (Enan et al., 2026).

The essential oils of clove are important in treating infections caused by biofilm causing bacteria, which are rather difficult to treat using conventional antibiotics The in vitro activity and substantial biofilm inhibition (up to about 90%) against many MDR bacteria such as E coli, Staph. aureus, and K. pneumoniae has been reported (Hu et al., 2018; Tariq et al., 2025). It has been found that essential oil of clove against Enterohemorrhagic E. coli can inhibit more than 75 % of biofilm formation. Clove extract prevents biofilm formation and disrupts the already formed biofilms, where it can reduce the expression of biofilm genes (ica operon) in Staph. aureus.

Quorum sensing (QS) is an advanced cell–cell communication process in which bacteria possess the synthesis, release, and subsequent detection of specific chemical signal molecules, known as autoinducers in their extracellular environment. In pathogens, QS controls the synthesis of important virulence factors. Clove extract has been discovered to suppress QS-controlled gene expression in P. aeruginosa (QSIS-lasI) and Chromobacterium violaceum (CV026), which has led to inhibition of biofilm formation (Zhou et al., 2013). According to several studies conducted on clove and eugenol have reported their ability to disturb membrane microdomains and interfere with signal transduction or ligand-receptor interactions at the cell surface. The tiny lipophilic phytophenols (like eugenol) may lower the strength of QS signaling and the expression of downstream virulence genes. QS-regulated genes are downregulated and biofilm biomass is decreased at sub-inhibitory doses (Al-Qareer et al., 2006; Al-Shabib et al., 2017). Clove bud’s extracts (i.e., hexane, chloroform, and methanol) have multi-target anti-QS activity, according to an interesting study reported by Ahamad (2024). Chloroform and methanol extracts have decreased E. coli bioluminescence, while hexane and methanol have effectively inhibited the production of violacein in Chromobacterium violaceum. Additionally, the clove flower buds extracts have inhibited several QS-regulated characteristics in P. aeruginosa, such as lecA:lux expression (hexane), swarming (methanol), and pyocyanin production (hexane). A natural competitive strategy known as quorum quenching (QQ) occurs when bacteria and other microorganisms release enzymes like lactonases and acylases to break down the QS signals. These enzymes inhibit the competing species’ pathogenicity and biofilm formation by interfering with intercellular communication (Sikdar and Elias, 2020). As a result, QS should be regarded as a complement to bactericidal approaches that may inhibit the development of antibiotic resistance (Tariq et al., 2025).

Eugenol may stop the synthesis of several virulence factors regulated by QS, including hemolysin, protease, and prodigiosin pigment. Furthermore, the eugenol’s treatment has suppressed the stages of QS-mediated biofilm formation, including swarming motility, microcolony formation, and extracellular polysaccharide production. Additionally, in Serratia. marcescens, eugenol has reduced the expression of genes related to the QS system, adhesion, motility, and biofilm formation. These findings imply that eugenol may have medicinal use, including anti-QS and antibiofilm actions against S. marcescens strains (Fekrirad et al., 2020).

Antimicrobial activity of nanomaterials

Nanoparticles (NPs) are materials whose molecular size has at least one dimension (1-100 nm) in the nanometer scale range (Edmundson et al., 2013). NPs have shown enhanced antibacterial activities against both Gram positive and Gram-negative bacteria, including the MDR. For example, ZnNPs have inhibited Staph. aureus, while AgNPs have effectively inhibited the MDR E. coli and P. aeruginosa (Ramalingam et al., 2016). Various studies have also demonstrated that CuNPs have a broad spectrum of inhibitory action against several Gram positive and Gram-negative bacteria, including the MDR-ones (El-Gazzar and Enan, 2020; Enan et al., 2026). Recently, MgNPs have displayed a pronounced antibacterial activity against MDR bacterial species namely: Staph. aureus, E. coli, B. cereus, K. pnemoniae, and others (Nguyen et al., 2018). However, the detailed modes of action of these NPs are that they can penetrate into the cells easily causing an oxidative stress induction, which leads to the release of RO intermediate, metal ion release, leakage of cell nutrients throughout the cell, causing the cells to be de-energized, followed by their death (Nguyen et al., 2022). In spite of these studies, the obvious modes of action of NPs are still under investigation. For instance, certain studies have shown that AgNPs cause neutralization of the electric charge at the surface of bacterial membranes and change its penetrability, ultimately leading to bacterial death (Jung et al., 2008). According to recent studies, the inhibitory activity of NPs is attributed to disruption of the bacterial cell membrane, leakage of cell nutrients, generation of ROS, and induction of intracellular bacterial deleterious effects such as modifications and degradations of cellular DNA and protein (Nguyen et al., 2018, 2022).

In a previous study conducted by El-Gazzar and Enan, (2020), NPs have been considered as an alternative to antibiotics as they inhibit the MDR bacteria. Thus, several studies have tried to find out safe innovative strategies to kill the MDR microorganisms, including NPs and phage (El-Gazzar and Enan, 2020)., phyto-extracts and NPs in composites (Stohy et al., 2024), modified proteins (Enan et al., 2023), and/or modified proteins combined with NPs (Sitohy et al., 2021). It has been reported that many NPs can prevent biofilm formation, including Ag-based NPs, Mg-based NPs, NONPs, ZnNPs, CuNPs, and Fe3O4NPs (Enan et al., 2026). Greater prevention of biofilm formation is achieved by a small size and higher surface area to mass ratio of the NPs. Moreover, the NP’s shape has also shown an obvious effect on biofilm disruption (Slomberg et al., 2013).

Nanoparticles as good carriers of antibiotics

Nanoparticles not only inhibit MDR bacteria but also can be used as carriers of antibiotics. Many types of NPs are commonly used as an antibiotic medium and are used for drug delivery, including liposomal NPs, solid lipid NPs, polymer-based NPs, inorganic nano-drug carriers (i.e., magnetic NPs), silica NPs, carbon NPs, and terpenoid-based NPs (Wang et al., 2017). The main advantages of using NPs as carriers for the delivery of antibiotics compared to the conventional delivery systems are their ultra-small structure, which enables them to enter into the bacterial cells easily, and have the ability to combat the intracellular small infectious microorganisms; thus, they can’t be easily phagocytosed. This makes it possible for many drugs to be released intracellularly from the extracellular environment (Andrade et al., 2013; Qi et al., 2013; Falsafi et al., 2020). The infectious bacteria that exist in blood serum can resist the action of antibiotics but can’t do so in case of NPs-conjugated antibiotics. This is because the antibiotics are protected around the NPs; thus, they can induce their inhibitory effect in synergism (Huh and Kwon, 2011). The NP’s carriers may also help to target the antibiotics toward the infection size, thereby minimizing their systemic side effects.

The high doses of antibiotics without carriers may cause drug toxicity. NP-based antibacterial drug delivery systems deliver the drug to the site of action and therefore reduce the side effects. Targeted NP-based drug delivery includes enhanced permeation and retention at the infection site, while active targeting occurs via rapid surface modification of NPs and enhanced recognition of specific ligands at the infection site (Wang et al., 2017). A previous study conducted by Qi et al. (2013) has reported that the antibiotic vancomycin strongly inhibits the Gram positive bacteria, but it may also cause ear and kidney toxicity. However, upon using NPs-vancomycin conjugates, drug delivery to the desired location becomes elevated, thereby decreasing the amount of drug reaching the unnecessary organs. The combinations of multiple drugs or antimicrobials can be packaged within the same NPs. Additionally, NPs can be combined with other constructs to improve their antibacterial properties. It is difficult for the bacterial cell to resist certain NPs combined with an antibacterial agent, because the small sizes NPs rupture the cell membrane causing the antibacterial agent to cross into the cells and induces its inhibitory effect (Wang et al., 2017).

On the other hand, two or more types of NPs can be used in combination to enhance their antibacterial effects and prevent development of resistance (Huh and Kwon, 2011). The disadvantages of liposomes are their short shelf life, poor stability, low encapsulation efficacy, rapid removal by the reticulo-endothelial system, cell interactions or adsorption, and inter-membrane transfer. Meanwhile, the disadvantages of solid lipid nanoparticles (Sl-NPs) are their unpredictable gelation tendency and inherent low incorporation rates (Liu et al., 2015). The hybrid NPs can increase the strengths and decrease the weaknesses of the individual types of NPs. For example, several studies have reported that better efficacy of the in vivo cellular delivery can be achieved by the lipid-polymer hybrid NPs, compared to the delivery without polymeric NPs or by liposomes alone (Andrade et al., 2013; Hadinoto et al., 2013). Moreover, a prolonged effective time can be achieved through the NPs “combination” way, which may effectively and substantially reduce the possibility of development of resistance in the bacteria (Brooks and Brooks, 2014).

Nanoparticles conjugated antibiotics have higher antimicrobial activity compared to either the antibiotics or the NPs singly. This is because, in addition to the above-mentioned explanations, they act in synergism as both polar and non-polar residues of the antibiotics and the NPs can be attached. This synergism enhances efficacy, reduces the required high antibiotic doses, and overcomes the bacterial resistance (Enan et al., 2026). The synergistic mechanism of the NPs (Ag or Cu or Mg) and the antibiotics act through attaching the bacteria via several complementary pathways, such as damaging cell walls, and inhibiting cells protein synthesis and RNA transcription. The NPs also act as carriers of the antibiotic, which can be delivered directly to the infectious microorganisms and bypass the resistance mechanisms, through efflux pumps and/or dissociating the antibiotic resistance genes (Wang et al., 2017).

Plant-based nanoparticles

The green synthesis of NPs is more preferable as it is non-toxic, uses available materials, has low cost, along with ease of collection (Nguyen et al., 2022). NPs are synthesized using microorganisms/biomolecules and plant metabolites. During biosynthesis of NPs, natural compounds that are available in the plant and the microbial extracts act as reducing and stabilizing agents. These basic compounds allow conversion of the metal into NPs (Dabhane et al., 2021). Plant extracts are preferable than either microorganisms or biomolecules because they can produce larger amounts of NPs with high efficacy and low production cost (Nguyen et al., 2022). The plants also exist in the ecosystem and can be gathered easily. They produce large amounts of phytochemicals that could replace the highly toxic, expensive, and non-ecofriendly harmful chemicals commonly used as reducing agents, such as sodium citrate, sodium borohydride, and ascorbate (Enan et al., 2026). Many reports have shown that the phytochemicals namely: flavonoids, terpenoids, polysaccharides, phenolic acids, and quercetins in the plant extracts are capable of reducing the metal ions such Cu2+, Au3+, Mn2+, and Mg2+ (Nguyen et al., 2022; David et al., 2026). These compounds have displayed capping, stabilizing, and chelating functions during the formation of NPs, and they can be extracted from the plant leaves, flowers, stems, and roots (Agarwal et al., 2017).

The green synthesized NPs are used for water treatment, as they can catalyze many reactions for the degradation of toxic pollutants from the aquatic environments. Moreover, they are used in many medical applications for treatment of various diseases, thereby acting as antibacterial, antifungal, anti-cancer agents (Khan et al., 2020). Additionally, they are used for food protection (Enan et al., 2026). For therapeutic effects, NPs are used for biomedical diagnosis and drugs delivery (Borzabadi-Farahani et al., 2014). Biosynthesized NPs remarkably contribute to the development of biomedical technology and environmental remediation (Nguyen et al., 2022).

Nanoparticles synthesized using phyto-extracts are formed throughout a top-down technique as phyto-extracts reduce the materials into their nanoforms. In addition, the biological methods used to synthesize NPs have many advantages over chemical techniques, as they are safe and highly biocompatible. Plant extracts mediated NP’s synthesis discloses several advantages because many phytochemicals act as bio-capping and bio-reducing agents during the fabrication processes, thereby increasing the NP’s stability (Abdullah et al., 2021). For example, Abinaya et al. (2021) have shown that plant extracts used to synthesize NPs bring higher efficacy, in addition to ease of handling, safer, and rapid, compared to the other biological methods. Once NPs are formed, many techniques are necessary to elucidate the biosynthesis processes such as ultraviolet-visible (UV-Vis) spectroscopy used to determine the optical properties, generation, and stability of the NPs (Forster, 2004). Fourier transform infrared (FT-IR) spectroscopy is used to learn about the surface chemistry of NPs and detect the presence of functional groups derived from biomolecules, which contribute to the synthesis of NPs. Scanning election microscopy (SEM) is a very diverse and important technique used to better understand the structure of NPs scope, size, and size distribution, while the atomic force microscopy (AFM) technique produces the three-dimensional images of NPs (Falsafi et al., 2020). Transmission election microscopy (TEM) gives a very high resolution to explore the inherent structure of NPs, observe their aggregations or clustering, and find out their size distribution (Fang et al., 2019). Finally, X-ray diffraction (XRD) pattern is a characteristic technique manipulated to analyze the crystal structure, crystal plane, and calculate the crystal size of the NPs (Nguyen et al., 2022).

Nanoparticles synthesized by plants have demonstrated antibacterial, antifungal, and antiproliferative activities (Wang et al, 2022; Enan et al., 2026). NPs act through penetrating the cell walls and membranes of bacteria and interact with cell’s protein and cell’s genome, leading to destruction of the genetic material (Basavegowda and Back, 2022). Latter published results have shown and approved the existence of synergism between NPs and extracts of medicinal plants through which the antimicrobial activity becomes increased, compared to using either NPs or plant extract individually (Bai et al., 2023; Bataineh et al., 2024).

The antibacterial efficacy of MgNPs has been studied by combining them with methanolic extracts of three medicinal plants possessing antimicrobial compounds: Aleysia triphylia, Sarcopoterium spinanom and Urtica pilulifera. The combined effect has been assessed against both wild type and resistant strains of Staph. aureus and E. coli. The antibacterial synergistic effect of MgNPs and plant extracts has been evaluated using the minimum inhibitory concentration (MIC) test, which has shown increased inhibitory properties against the growth of two bacterial strains, compared to control samples of the plant extracts alone. Furthermore, the synergistic effect of MgNPs combined with phyto-extracts from Rosmarinus officinalis, Anchusa azuras, Quercus infectoria, and Urtica pilulifera considerably prevented biofilm development in both sensitive and resistant strains of Staph. aureus (Bataineh et al., 2024; Enan et al. 2026). Enan et al. (2026) have studied the effect of Fe3O4- NPs-Salvia officinalis extract combined conjugate against different Gram positive and Gram-negative bacteria that have resisted the action of different antibiotics. The antibacterial spectrum of this composite is more effective against various MDR bacteria such as Staph. pasteuri, Listeria monocytogenes, B. cereus, E. coli, P. aeruginosa, and Proteus mirabilis, compared to that obtained individually by either Fe3O3-NPs or Salvia officinalis extract.

Conclusions and Recommendations

The appearance of multidrug resistant (MDR) bacteria causes a mandatory need to develop innovative natural agents to be used for controlling these MDR bacteria, either singly or in combination and/or with antibiotics. In this regard, nanoparticles have shown a promising inhibitory effect against MDR bacteria such as CuO-NPs, ZnO-NPs, Al-NPs, and others. This is because the small molecular size of NPs (<100 nm) enables them to rupture the bacterial cells wall and membrane, followed by entering the cells, leading to a leakage of cell’s nutrients, converting the cells to de-energized death cells. NPs also integrate and conjugate the cell’s genomes, defecting DNA replication and gene expression. It has been found that the biologically synthesized NPs are better than the chemically produced ones, as they are safer and cheaper, and are produced in large amounts. Using NPs combined with antibacterial phyto-extracts may provide better antibacterial activity as they help in delivery of antibacterial agents into the cells, thereby escaping from phagocytosis. Phyto-extracts from different medicinal plants can inhibit MDR bacteria, either singly or in combination with NPs. Lemon and clove are two promising plants containing many bioactive compounds that may be used effectively to green synthesize the NPs. The study recommends the use of phyto-extracts and nanoparticles, either singly or in combination, for controlling multidrug resistant bacteria either in foods as food protectives or as antiseptics for skin infections.

Acknowledgement

The authors acknowledge the Faculty of Science, Zagazig University for providing the facilities.

Novelty Statement

The novelty of this study lies in the development of phyto-extracts and nanoparticles-based strategies for controlling multidrug resistant bacteria as a promising task to develop novel antimicrobial agents to be used either for therapy or food preservation.

Authors’ Contribution

SS: Collection of surveyed literature, writing-review. NE-G and RA: Reviewing, editing. AA: Revision. ARA: Editing, reviewing, and funding.

Ethical approval

Not applicable.

Funding source

This study is in the framework of Mrs. Safaa Saed PhD-Scholarship of Zagazig University. Dr. Al-Mohammadi has financed the publication fees.

Generative AI and AI assisted technology statement

The authors declare that no generative AI and AI assisted technology was used in the creation of this manuscript.

Conflict of interests

The authors have declared no conflicts of interest.

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