Available online on 15.03.2021 at http://jddtonline.info

Journal of Drug Delivery and Therapeutics

Open Access to Pharmaceutical and Medical Research

Open Access Full Text Article Review Article

Highlights on the alternatives to antibiotic therapy against bacterial infection

Bijayanta Sircar, Shyamapada Mandal*

Laboratory of Microbiology and Experimental Medicine, Department of Zoology, University of Gour Banga, Malda-732103, India

Article Info:

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Article History:

Received 11 Feb 2021;

Review Completed 21 Feb 2021

Accepted 04 March 2021;

Available online 15 March 2021

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Cite this article as:

Sircar B, Mandal S, Highlights on the alternatives to antibiotic therapy against bacterial infection, Journal of Drug Delivery and Therapeutics. 2021; 11(2):194-203 DOI: http://dx.doi.org/10.22270/jddt.v11i2.4596

Abstract

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The antibiotic resistance among gram-positive and gram-negative pathogenic bacteria is of global health concern. This has prompted the development of new effective drugs. But the discovery and development of new drugs is slow, and the emergence of resistance to such new drugs, on the other hand, is rapid as well as continuous among the bacteria. Therefore, in tackling the emergence of antibiotic resistant pathogenic bacteria finding alternative ways is vital. This communication, based on the published scientific data, summarizes the antibacterial capacity of some naturally derived agents such as honey, phytocomponents, probiotics, and antimicrobial peptides that might bring new essence in biomedicine.

Keywords: Bacterial resistance, alternative therapeutics, honey, phytomedicine, probiotics, antimicrobial peptides.

*Address for Correspondence:

Dr. Shyamapada Mandal, Professor, Department of Zoology, University of Gour Banga, Malda-732103, India E-mail: samtropmed@gmail.com

Introduction

Emergence of bacterial antibiotic resistance developed through an array of mechanisms is a severe threat to humans, and such phenomenon has been marked as an global alarming problem, which in developing countries including India, as recognised by the WHO, is reaching critical levels¹. The multidrug resistant (MDR) ESKAPE (gram-positive: Enterococcus faecium and Staphylococcus aureus, and gram-negative: Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) bacteria are among the most notorious to cause life threatening nosocomial infections². The continuous antibiotic therapy as well as the lack of effective antibiotics in the existing global treatment regimen has directed to a major upsurge in antibiotic resistance³. The increasing trend of development of antibiotic resistance among pathogenic bacteria has been associated with a marked economic cost worldwide. As the consequences there are great mortality and morbidity, high treatment costs, diagnostic doubts, and deficiency of trusted conventional medicine². Of the six notorious ESKAPE pathogens, the four gram-negative bacteria, have been associated with four main types of multi-drug resistance, specifically the extended-spectrum β-lactamase-producing K. pneumoniae and Enterobacter spp., carbapenemase-producing A. baumannii and metallo-β-lactamase producing Ps. aeruginosa limiting the therapeutic choices⁴. K. pneumoniae is presently developing as a noticeable opportunistic pathogen and the most challenging agent of nosocomial infections⁵.

Exposure of the pathogenic bacteria to antibiotics surges the risk of the emergence of carbapenem resistant Enterobactericeae, too. Carbapenems and cephalosoprins are cause of resistance that increased the risk up to 15-fold and 6 - 29 folds, respectively¹. The widespread antibiotic usage in communities and hospitals cause severe multidrug resistance among gram-negative bacteria. The ESBL-mediated MDR gram-negative ESKAPE pathogens are progressively associated with several conditions that are difficult to treat in both developed and developing nations⁴. Current researches have shown pronounced interest in the use of alternative agents including honey, phytomedicine, probiotics, and antimicrobial peptides, in targeting the bacterial resistance corroborating their potential in the treatment of diseases caused by a large number of bacteria displaying resistance to almost all the antibiotics. This study thus provides a highlight on the antibacterial capacity of some naturally available agents, based on the scientific information published in the field.

Antibacterial activity

The indiscriminate use of antibiotics causes the development of antibiotic resistance among pathogenic bacteria leading to high morbidity and mortality from infections caused by such pathogens⁶. In the current times, there has been an increasing interest in exploring and evolving new antimicrobial biotherapeutics from various sources to fight bacterial resistances⁷. Along with the growing incidence of antibacterial resistance, complete and effective investigation is needed to look for the natural antibacterial sources, such as honey, plants, probiotics providing several active compounds having antibacterial activity that could inhibit life threatening bacterial diseases (Figure 1).

Figure 1: Schematic representation of different alternative antibacterials against human pathogenic bacteria.

2.1. Honey

Recently it has been proved experimentally that honey display antibacterial, anti-inflammatory and antioxidant activities, which may be useful in opposing MDR bacteria as well as in inhibiting many prolonged inflammatory processes⁸. The antibacterial activity of honey against clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica serovar Typhi has been reported previously⁹. Some factors that present in the honey as antimicrobials include hydrogen peroxide (H₂O₂) and inhibin, and also the osmotic effect of honey, its low pH (3.2 – 4.5), defensin-1, as well as the presence of phytochemical components display antibacterial activity¹⁰.

Most of the researchers performed the disc diffusion or well diffusion method to study the antibacterial activity of honey. Several articles on antibacterial activity of different honey samples from diverse region of the world that has been published are summarised in Table 1.

Table 1: Antibacterial activity of honey

Honey type	Geographical location	Using condition	Activity against bacteria	Antibacterial activity		Ref
Honey type	Geographical location	Using condition	Activity against bacteria	ZDI (mm)	MIC (%)	Ref
Commercial grade honey	Malda, India	Aqueous honey	Gram negative: Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and E. coli ATCC 25922 Gram positive: Staphylococcus aureus	6 – 30	ND	8
Natural jujube honey	Saudi Arabia	Methanol extract	Gram negative: E. coli ATCC 35218, Klebsiella pneumoniae ATCC 700603, and K. pneumoniae ATCC 27736 Gram positive: S. aureus ATCC 25923, Staphylococcus epidermidis ATCC 12228, Enterococcus faecalis ATCC 29212, Bacillus cereus ATCC 10876,	6 – 17	ND	11
Eucalyptus honey and commercial grade honey	Mauritius	Undiluted	Gram negative: Proteus sp., Klebsiella sp., Pseudomonas 161 sp., and E. coli, E. coli ATCC 25922, and Ps. aeruginosa ATCC 27853 Gram positive: Streptococcus sp., S. epidermidis ATCC 35984, and S. epidermidis ATCC 14990	6 – 28	ND	12

Table 1: (Continued)

Honey type	Geographical location	Using condition	Activity against bacteria	Antibacterial activity		Ref
Honey type	Geographical location	Using condition	Activity against bacteria	ZDI (mm)	MIC (%)	Ref
Blossoms honey	Slovakia	50% honey solution	Gram negative: Ps. aeruginosa CCM1960 Gram positive: S. aureus CCM4223	ND	3 – 27	13
Wildflower and bitter leaf honey	Nigeria	Raw honey	Gram negative: Salmonella typhimurium ATCC 14028, Sal. typhimurium clinical, Shigella dysenteriae ATCC 11836, Sh. dysenteriae (clinical), E. coli ATCC 700728, E. coli (clinical) Gram positive: B. cereus ATCC 14579, B. cereus (clinical), S. aureus ATCC 29213 and S. aureus (clinical)	6 – 26	ND	14
Natural honey	Ethiopia	Aqueous honey	Gram positive: Methicillin-resistant S. aureus	6 – 39	9.38–37.5	15
Citrus honey and mango honey	Malda, India	Aqueous honey	Gram negative: Salmonella enterica serovar Typhi, Ps. aeruginosa and E. coli ATCC 25922 Gram positive: S. aureus	15 – 35	ND	16
Local honey	Pakistan	Aqueous honey	Gram negative: E. coli ATCC 25922, Ps. aeruginosa ATCC 27853, S. typhi ATCC 19943 and K. pneumoniae ATCC 27736 Gram positive: S. aureus ATCC 6538, En. faecalis ATCC 19433	14 – 37	ND	17
Natural (Kombu and Vembu) and commercial grade honey	Vellore, India	Honey diluted with dimethyl sulfoxide	Gram negative: E. coli, S. typhi, Proteus mirabilis, K. pneumoniae, Shigella flexneri and Ps. aeruginosa Gram positive: S. aureus, B. cereus and Enterococcus casseliflavus	6 – 38	ND	18
Acacia, abies, sideritis, herbs, polyfloral and conifers honeys	Mount Olympus area, Greece	Raw honey	Gram negative: A. baumannii, Citrobacter freundii, K. pneumoniae, and Salmonella typhimurium Gram positive: Streptococcus infantis	ND	6.25–12.5	19

MIC: minimum inhibitory concentration, ND: not done, ZDI: zone diameter of inhibition

2.2. Phytomedicines

Roots, leaves, seeds, bark or other part of medicinal plants possess therapeutic, tonic, purgative or other pharmacologic activity under in vitro as well as in vivo conditions. Several plants are used in various countries as the source of potent and powerful medicines²⁰. Alkaloids, norsecurinines, phyllanthine, phyllochrysine, saponins, quercetin, quercetol, rutin, quercitrin, astragalin, gallocatechins, niruretin, nirurin, brevifolin, ellagic acid ellagitannins, repandusinic acids, geraniin, carboxylic acids, corilagin, cymene, lupeols, phyllanthenol, lignans, hypophyllanthin, niranthin, nirtetralin, lintetralins, methyl salicylate, niruriside, triacontanal, tricontanol etc. type of bioactive compounds are present in various plants as the source of therapeutic components²¹.

The innovation of medicinal plants in different parts of the globe is vital to the agriculture and medicine sectors, in defining the new guidelines towards spread of unconventional medicinal crops that offer improved commercial welfares²². Some tribal communities are mostly dependent upon the natural resources for their traditional food habits as well as for treating common illnesses such as diarrhoea, dysentery, vomiting, headache, cold, and fever²³.

Indian flora deals countless possibilities for the detection of new compounds with important medicinal uses in opposing infection. The antimicrobial compounds found in plants may inhibit bacterial toxicities by alternative mechanisms than the conventional one²⁴. Phytomedicine, prepared from different plant materials, such as Ayurvedic traditional medicine, are relatively safe, cost effective and have less or no side effects²⁵.

Most of the current in vitro study on different medicinal plants with their experimental particulars, in terms of the antibacterial activity, are summarized in Table 2, where some research on bioactive fruit plants and spice herbs are also included.

Table 2: Antibacterial activity of different plant extracts

Plants	Plant parts	Extracting solvent	Activity against Bacteria	Antibacterial activity		Ref
Plants	Plant parts	Extracting solvent	Activity against Bacteria	ZDI (mm)	MIC (µg/ml)	Ref
Medicinal plants
Aegle marmelous (Bael)	Leaves	Hexane, acetone, ethanol, and aqueous	Gram negative: E. coli, Ps. aeruginosa, Salmonella enterica, Shigella sonnei Gram positive: Bacillus cereus, Strep. faecalis, Listeria innocua, Micrococcus luteus	ND	297 – 551	23
Azardirchata indica	Leaves and bark	Ethanol, chloroform and methanol	Gram negative: Aeromonas hyprophila, A. hyprophila ATCC 7966, Ps. aeruginosa, Proteus mirabilis, Shiga-toxigenic E. coli Gram positive: S. aureus, S. aureus ATCC 25923, Enterococcus faecalis, Methicillin-resistant S. aureus	6 – 27	500 – 12500	26–29
Withania somnifera (Aswagandha)	Leaves	Ethyl acetate and methanol	Gram negative: E. coli ATCC 25922, Proteus mirabilis ATCC 35659, Ps. aeruginosa ATCC 27853, Pseudomonas syringae pv. Phaseolicola and Xanthomonas campestris pv. Phaseoli Gram positive: S. aureus ATCC 25923, Streptococcus pneumoniae ATCC 49619, En. Faecalis ATCC 29212	7 – 13	6.25 – 2500	30, 31
Bacopa monnieri (Brahmi)	Whole plant and leaves	Methanol, acetone, ethanol and methanol	Gram negative: E. coli K 88, Ps. aeruginosa, Salmonella typhii 62, Shigella dysenteriae 3, E. coli, K. pneumoniae and K. pneumoniae MTCC 109 Gram positive: S. aureus ATCC 6571, Streptococcus faecalis 52, En. faecalis ATCC 29212, S. aureus MTCC 3160 and B. subtilis MTCC 441	8 – 22	30 – 25000	32, 33
Santalum album (Sandal wood)	Heartwood	n-hexane, water chloroform, acetone, butanol ethylacetate and ethanol	Gram negative: E. coli 25922, E. coli 35318 and Shigella sonnei BB-8 Gram positive: S. aureus 25923, S. aureus 38541, Streptococcs pyrogenes Tc-11-2 and Neisseria gonorrhoeae 4c-11	6 – 17	ND	34
Ranwolfia serpentina (Sarpa gandha)	Leaves, Roots and leaves	Acetone, methanol and ethanol	Gram negative: E. coli and S. typhi Gram positive: S. aureus, B. cereus and B. subtilis	7 – 22	4000 - 9000	20, 35
Ocimum sanctum (Tulsi)	Leaves	Aqueous, acetone and ethanol	Gram negative: K. pneumoniae, E. coli, Pr. vulgaris, Ps. aeruginosa, S. typhi, Acinetobacter baumannii and E. coli MTCC 443 Gram positive: Streptococcus mitis, Streptococcus viridans, S. aureus, B. cereus and Listeria monocytogenes MTCC 657	6 – 28	ND	36, 37
Mentha pipertia (Pippermint)	Leaves	Ethanol, chloroform and hexane	Gram negative: E. aerogenes and S. typhimirium Gram positive: S. aureus, B. subtilis and Propioni bacterium acnes MTCC 1951	7 – 8	312 – 1150	38, 39

Table 2: (Continued)

Plants	Plant parts	Extraction solvent	Activity against bacteria	Antibacterial activity		Ref
Plants	Plant parts	Extraction solvent	Activity against bacteria	ZDI (mm)	MIC (µg/ml)	Ref
Phyllanthous amarus (Bhumi amla)	Whole plant and leaves	Aqueous, n-hexane, ethyl acetate and methanol	Gram negative: E. coli, Ps. aeruginosa and Pseudomonas spp. Gram positive: Coagulase positive S. aureus and S. aureus	9 – 26	ND	21, 40
Enhydra fluctuans (helencha)	Whole aerial parts (stem and leaves)	Methanol and aqueous	Gram negative: A. baumannii, Ps. aeruginosa and E. coli ATCC25922 Gram positive: B. cereus, Listeria monocytogenes and L. monocytogenes MTCC657	6 – 24	2500 - 10000	41
Fruit plants
Elaeocarpus floribundus (Indian olive)	Seed and mesocarp-epicarp of mature fruits	Ethanol and aqueous	Gram negative: E. coli, Pr. vulgaris and Ps. aeruginosa ATCC 27813 Gram positive: B. cereus, S. aureus and L. monocytogenes MTCC 657	6 – 22	ND	42
Mimusops elengi (Bakul)	Seed	Ethanol	Gram negative: E. coli, Pr. vulgaris, K. pneumonia, E. coli ATCC 25922, K. pneumonia MTCC 7407 and Ps. aeruginosa ATCC 27853	7 – 17	ND	25
Syzygium cumini (Jamun)	Seed	Ethanol	Gram negative: E. coli, K. pneumonia and E. coli ATCC 25922 Gram positive: S. aureus and S. aureus ATCC 29213	8 – 15	ND	43
Mangifera indica (Mango)	Seed	Ethanol		10 – 20	ND
Punica granatum (Pomegranate)	Fruit Peel	Ethanol and aqueous	Gram negative: E. coli, Proteus spp., K. pneumoniae, P. aeruginosa, A. baumannii	6 – 28	2500 – 20000	44
Spices
Piper nigrum (Black pepper)	Corn	Ethanol and chloroform	Gram negative: E. coli, Ps. aeruginosa, Klebsiella Sp, Proteus Sp. Gram positive: Streptococcus mutans, Coagulase negative Staphylococci and S. aureus	6 – 29	ND	45, 46

KOH: potassium hydroxide, MIC: minimum inhibitory concentration, ND: not done, ZDI: zone diameter of inhibition

2.3. Probiotics

Probiotics, in the form of lactic acid bacteria (LAB), generally the lactobacilli, might be crucial in controlling the emerging antibiotic resistant pathogenic bacteria. Probiotics have the inhibition property against bacterial pathogens, including the antibiotic resistant individuals: spoilage, food-borne and pathogenic bacteria, by producing H₂O₂, lactic acid and bacteriocin⁴⁷. Sheep and goat milks and their derivatives (cheese and yoghurt) are commercially available as functional foods, which are with nutritional as well as medicinal importance, and can be selected as valid candidates having microbiological and technological qualities⁴⁸. Current studies revealed that some lactic acid bacteria isolated from non-milk fermented foods act as potential probiotics with huge nutritional as well as medicinal values that might be due to the production of bacteriocins^49,50. In the intestine, probiotic microorganisms compete with pathogenic bacteria in terms of nutrients and cell-surface for colonization, and can create inhibition against biofilm formation and quorum sensing properties of many pathogens^{51 – 53}.

The milk and non-milk food-based probiotics, being isolated and characterised by the scientists from around the world, are summarized, in terms of the effectiveness against bacteria, in Table 3.

Table 3: Antibacterial activity of probiotics

Source	Geographical location	Probiotic strain	Activity against bacteria	Antibacterial activity			Ref
Source	Geographical location	Probiotic strain	Activity against bacteria	ZDI (mm)		MIC	Ref
Milk-based products
Local fermented milk products	Bangkok region of Thailand	Lactococcus lactis subsp. lactis	Gram negative: E. coli, Ps. aeruginosa and S typhimurium Gram positive: B. cereus and S. aureus	11 – 27		ND	54
Toraja Belang buffalo milk	Indonesia	Enterococcus faecalis	Gram negative: Enteropathogenic E. coli ATCC 25922, and S. typhi ATCC 58105535 Gram positive: S. aureus 134-P	6 – 13		ND	55
Home-made cow milk curd, commercial curd	Malda district, India	Lactobacillus animalis LMEM6, Lactobacillus plantarum LMEM7, Lactobacillus acidophilus LMEM8 and Lactobacillus rhamnosus LMEM9	Gram negative: S. enterica serovar Typhi, E. coli, P. vulgaris and A. baumannii	11 – 35		ND	56
Commercially available curd	Malda district, India	Lactobacillus fermentum	Gram negative: A. baumannii, Ps. aeruginosa, E. coli, Pr. vulgaris, K. pneumoniae, S. enterica serovar Typhi Gram positive: S. aureus, B. cereus, E. faecalis, L. monocytogenes	10 – 20		ND	57
Sheep and goat raw milk	Tunisia	L. plantarum and L. pentosus	Gram negative: S. thyphimirium ATCC 25922 and E. coli Gram positive: S. aureus ATCC 25923, L. monocytogenes ATCC 070 101 121	6 – 12		ND	48
Non milk-based products
Home-made fermented vegetables	Malaysia	Lactobacillus sp	Gram negative: Yersinia enterocolitica and E. coli Gram positive: S. aureus ATCC 25923, B. cereus	6 – 20	ND			49
Fermented plant beverages and pickles	Thailand	Lactobacillus casei and L. plantarum	Gram negative: S. thyphimirium PSSCM10035, S. typhi PSSCM10034, E. coli O157:H7, E. coli ATCC 25922, Shigella sonnei PSSCM10032, Shigella flexneri PSSCM10035, Pr. vulgaris PSSCM10041, Providencia rettgeri psscm10044, Enterobacter cloacae PSSCM10040, Enterobacter aerogenes PSSCM10039, Vibrio parahaemolyticus VP4 Gram positive: S. aureus ATCC 25923, B. cereus ATCC11778	7 – 10	ND			50
Vegetables and traditional Indian fermented foods	India	L. fermentum, L. plantarum Weissella confusa, Weissella cibaria and Pediococcus parvulus	Gram negative: E. coli K12	14 – 23	ND			58

MIC: minimum inhibitory concentration, ND: not done, ZDI: zone diameter of inhibition

2.4. Antimicrobial peptides

Several authors reported that antimicrobial peptides (AMPs) can be administered as typical candidates effective against different MDR bacterial strains. Biofilms formation by the bacterial cells causes more resistant to antibiotic managements than the planktonic forms of the same bacterial strains⁵⁹. Food protein hydrolysates and fermented food products serves as promising source of bioactive AMPs. The caseins and whey proteins are major milk precursors proteins found in cow milk. Caseins derived bioactive peptides consists of about thirty different constituents comprising with genomic variations, mainly of αs- (αs1-, αs2-), β, and κ-casein⁶⁰. Most of the potential AMPs are cationic as well as amphipathic in nature consisting of a minimum five to maximum hundred amino acids. Current studies have shown that some probiotics can synthesise AMPs that contribute significantly to host survivability, exclusively against pathogenic bacteria. Although scientists are facing some difficulties in obtaining significant and economically sustainable quantities of AMPs, and thus they are trying to manufacture heterologous endogenous AMPs using cloning technique⁶¹.

Recently, a number of anionic antimicrobial peptides have been identified in vertebrates, invertebrates and plants⁶². The vast source of antimicrobial peptides is marine organisms because of their close contact with microbes⁵⁹. Some antimicrobial peptides derived from plants are mostly composed of cystine-rich peptides. Insects is one of the major sources of antimicrobial peptides that show inhibition against bacteria, fungi, viruses as well as some parasites. These can be classified into four families: the α-helical peptides (cecropin and moricin), glycine-rich peptides (gloverin and attacin), proline-rich peptides (drosocin, apidaecin and lebocin) and cysteine-rich peptides (insect drosomycin and defensin)⁶³.

Recent studies showed antimicrobial peptides can potentially serve as novel antimicrobial agents. Different AMPs can be utilized by innate immune cells and proteins to counterbalance microbial infections, and contribute more to other cellular and/or biomolecular pathways⁶⁴. Table 4 summarizes the antibacterial activities of AMPs with molecular weight ranging from 1.55 to 41.44 kDa.

Table 4: Antibacterial activity of different bioactive peptides

Source	Amino acid number in peptides	Molecular weight (kDa)	Activity against bacteria	Antibacterial activity			Ref
Source	Amino acid number in peptides	Molecular weight (kDa)	Activity against bacteria	ZDI (mm)	MIC (µg/ml)	AU/ml	Ref
Sea Cucumber, Holothuria tubulosa	14 – 36	1.55 – 4.09	Gram positive: Listeria monocytogenes	ND	1200 – 5000	ND	59
Bacteriocin from Lactococcus lactis MMFII (from a Tunisian dairy product)	~40	25 – 41.44	Gram positive: Enterococcus faecalis JH22 E. faecalis V583 Listeria ivanovi BUG 496	ND	0.05 – 0.1	20 – 60	65
Bacteriocin produced by Lactobacillus plantarum KLDS1.0391 (from fermented cream from China)	ND	21.80 – 29.70	Gram negative: Salmonella typhimurium	ND	ND	80	66
Marine Ascidian Didemnum sp.	ND	< 40	Gram negative: Ps. aeruginosa ATCC 27853, Salmonella typhimurium ATCC 202165 Gram positive: Staphylococcus aureus ATCC 6538, Serratia marcescens ATCC 14756 and E. faecalis ATCC 29212	7 – 11	1.83 – 2.30	ND	67
Soybean, Glycine max	ND	<10	Gram negative: Acinetobacter genomospecies, Aeromonas hydrophila FDA110-36, A. hydrophila ATCC7966, Escherichia coli DH5alf, E. coli ATCC43895, E. coli NCTC8959, Salmonella enterica ATCC12325, S. enterica ATCC29934, Vibrio parahaemolyticus ATCC17802 Gram positive: S. aureus ATCC14458, coagulase-negative S. saprophyticus KT955005, S. aureus ATCC13150	ND	72 – 1050	ND	68

Table 4: (Continued)

Source	Amino acid number in peptide	Molecular weight (kDa)	Activity against bacteria	Antibacterial activity			Ref
Source	Amino acid number in peptide	Molecular weight (kDa)	Activity against bacteria	ZDI (mm)	MIC (µg/ml)	AU/ml	Ref
Laba garlic	5 – 6	4 – 6	Gram negative: E. coli, ATCC 25922, S. enteritidis BNCC103134, Gram positive: B. subtilis ATCC 6633, and S. aureus ATCC 25923	9 – 27	100 – 450	ND	69
Skin Secretion of the Fujian Large Headed Frog, Limnonectes fujianensi	33	ND	Gram negative: E. coli NCTC 10418 Gram positive: S. aureus NCTC 10788	ND	16 – 32	ND	70
Moss Physcomitrella patens	14 – 18	ND	Gram negative: E. coli K-12 substr. MG1655 Gram positive: B. subtilis 168HT	ND	16 – 128	ND	71
Trianthema portulacastrum Leaves	ND	5.57 – 23.44	Gram negative: E. coli Gram positive: B. subtilis and S. aureus	6 - 14	ND	ND	72
Rumen microbiome	<25	ND	Gram negative: A. baumannii	ND	64 – 128	ND	73
Rana arvalis	13 – 32	ND	Gram negative: E. coli ATCC 25922, Acinetobacter baumannii ATCC 19606 Gram positive: S. aureus ATCC 29213 and En. faecalis ATCC 29212	ND	16 - >64 µM	ND	74

AU/ml: arbitrary unit per millilitre, MIC: Minimum inhibitory concentration, ND: not done, ZDI: zone diameter of inhibition

Concluding remarks

Due to the problem of antibiotic inactivity, exploration of alternative new antibacterial agents is needed to combat several life-threatening infections caused by MDR bacteria. Honey, plant extracts, probiotics and AMPs can inhibit the growth of infectious bacterial pathogens, as non-antibiotic antibacterials. Although, more specific experiments are required to know the effective dose dependent pharmacokinetic nature of the explored agents.

References

De AS, Baveja S, D’Souza D et al. Antimicrobial resistance among commonly encountered bacteria isolated in 2013 – The ESKAPE Menace, Internal Medicine, 2015; 5(193):1-6. DOI:10.4172/2165-8048.1000193
Rice LB, Progress and challenges in implementing the research on ESKAPE pathogens, Infection Control & Hospital Epidemiology, 2010; 31(1):S7–S10. DOI: 10.1086/655995
Santajit S, Indrawattana N, Mechanisms of antimicrobial resistance in ESKAPE pathogens,

BioMed Research International, 2016; Article ID 2475067, 8 pages. DOI: 10.1155/2016/2475067

Founou RC, Founou LL, Essack SY, Extended spectrum beta-lactamase mediated resistance in carriage and clinical gram-negative ESKAPE bacteria: a comparative study between a district and tertiary hospital in South Africa, Antimicrobial Resistance & Infection Control, 2018; 7(134):1-11. DOI: 10.1186/s13756-018-0423-0
Blin C, Passet V, Touchon M et al., Metabolic diversity of the emerging pathogenic lineages of Klebsiella pneumoniae, Wiley-Blackwell and Society for Applied Microbiology, 2017; 19(5):1881-98. DOI: 10.1111/1462-2920.13689
Azzahra S, Parisa N, Fatmawati et al., Antibacterial efficacy of Aloe vera sap against Staphylococcus aureus and Escherichia coli, Bioscientia Medicina 2019; 3(2):29-37.
Haque SD , Saha SK, Salma U et al., Antibacterial effect of Aloe vera (Aloe barbadensis) leaf gel against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae, Mymensingh Medical Journal, 2019; 28(3):490- 496.
Saha A, Mandal S, In vitro Assessment of two commercial honey samples for antibacterial and antioxidant activities, Austin Journal of Tropical Medicine & Hygiene, 2015; 1(1):1-5.
Mandal S, Mandal MD, Pal NK et al., Antibacterial activity of honey against clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Salmonella enteric serovar Typhi. Asian Pacific Journal of Tropical Medicine, 2010; 3(12):961-964. DOI: 10.1016/S1995-7645(11)60009-6
Hegazi AG, Abd Allah FM, Antimicrobial activity of different Saudi Arabia honeys, Global Veterinaria, 2012; 9(1):53-59. DOI: 10.14202/vetworld.2017.233-237
Abdallah EM, Hamed AE, Screening for antibacterial activity of two jujube honey samples collected from Saudi Arabia, Journal of Apitherapy, 2019; 5(1):6–9. DOI: 10.5455/ja.20190120035814
Aumeeruddy MZ, Aumeeruddy-Elalfi Z, Neetoo H et al., Pharmacological activities, chemical profile, and physico-chemical properties of raw and commercial honey, Biocatalysis and Agricultural Biotechnology, 2019; 18:101005. DOI: 10.1016/j.bcab.2019.01.043.
Bucekova M, Jardekova L, Juricova V et al., Antibacterial activity of different blossom Honeys: New findings. Molecules, 2019; 24(1573):1-20. DOI: 10.3390/molecules24081573
John-Isa JF, Adebolu TT, Oyetayo VO, Antibacterial effects of Honey in Nigeria on selected Diarrhoeagenic bacteria, South Asian Journal of Research in Microbiology, 2019; 3(2):1-11. DOI: 10.9734/sajrm/2019/v3i230083
Mama M, Teshome T, Detamo J, Antibacterial activity of Honey against Methicillin-Resistant Staphylococcus aureus: A laboratory-based experimental study, International Journal of Microbiology, 2019; Article ID 7686130, 9 pages, DOI: 10.1155/2019/7686130
Roy S, Mandal M, Pal NK et al., Exploration of antibacterial and antioxidative property of two natural Honey samples from Malda District, India, Translational Medicine (Sunnyvale) 2016; 6(4): DOI: 10.4172/2161-1025.1000187
Shah T, Ali N, Shah Z et al., Antibacterial activity of Pakistani Honey, Pakistan Journal of Scientific and Industrial Research Series B: Biological Sciences, 2019; 62B(2):97-100.
Suganthi K, Saranraj P, Antibacterial and anticandidal activity of Natural and Commercial Honey - A comparative study, Asian Journal of Applied Research, 2018; 4(3):37-41. DOI: 10.20468/ajar.2018.02.06
Tsavea E, Mossialos D, Antibacterial activity of honeys produced in Mount Olympus area against nosocomial and foodborne pathogens is mainly attributed to hydrogen peroxide and proteinaceous compounds, Journal of Apicultural Research, 2019; 58(5):756-63. DOI: 10.1080/00218839.2019.1649570
Deshmukh SR, Ashrit DS, Patil BA, Extraction and evaluation of indole alkaloids from Rauwolfia Serpentina for their antimicrobial and antiproliferative activities, International Journal of Pharmacy and Pharmaceutical Sciences, 2012; 4(5):329-334.
Shrivastav A, Shrivastav N, Antibacterial activity of Bhui amla (Phyllanthus niruri), Pharma Science Monitor, 2017; 8(4):222-228.
Zaidan MRS, Noor Rain A, Badrul AR et al., In vitro screening of five local medicinal plants for antibacterial activity using disc diffusion method, Tropical Biomedicine, 2005; 22(2):165–170.
Panda SK, Mohanta YK, Padhi L et al., Antimicrobial activity of select edible plants from Odisha, India against food-borne pathogens, LWT - Food Science and Technology, 2019; 9(4): 435. DOI: 10.1016/j.lwt.2019.06.013
Yadav SS, Dahiya K, Ganie SA et al., Antibacterial activity of Aegle marmelos (L) Correa, International Journal of Pharmacy and Pharmaceutical Sciences, 2015; 7(3):462-464.
Sircar B, Mandal S, Antibacterial activity of Mimusops elengi leaf, seed and bark extracts Alone and in combination with antibiotics against human pathogenic bacteria, Translational Medicine (Sunnyvale), 2016; 6(4):188. DOI: 10.4172/2161-1025.1000188
Devi NP, Das SK, Sanjukta RK et al., A comparative study on antibacterial activity of integumentary extract of selected freshwater fish Species and Neem extracts against gram-positive and gram-negative bacteria, Journal of Entomology and Zoology Studies, 2019; 7(2):1352-1355.
Senapati S, Bagchi A, Raha A et al., Evaluation of antimicrobial activity of Azadirachta indica bark extract, The Pharma Innovation Journal, 2019; 8(6):691-694.
Singaravelu S, Sankarapillai J, Chandrakumari AS et al., Effect of Azadirachta indica crude bark extracts concentrations against gram-positive and gram-negative bacterial pathogens. Journal of Pharmacy and Bioallied Sciences, 2019; 11(1):33–37. DOI: 10.4103/jpbs.JPBS_150_18
Zihadi MAH, Rahman M, Talukder S et al., Antibacterial efficacy of ethanolic extract of Camellia sinensis and Azadirachta indica leaves on methicillin-resistant Staphylococcus aureus and shiga-toxigenic Escherichia coli. Journal of Advanced Veterinary and Animal Research, 2019; 6(2):247–52. DOI: 10.5455/javar.2019.f340
Rezaie Keikhaie K, Fazeli-Nasab B, Jahantigh HR et al., Antibacterial activity of ethyl acetate and methanol extracts of Securigera Securidaca, Withania Sominefra, Rosmarinus Officinalis and Aloe vera plants against important human pathogens, Journal of Medical Bacteriology, 2018; 7 (1, 2):13-21.
Chepkorir R, Matasyoh JC, Wagara IN, Two withanolides from Withania somnifera (solanaceae) and activity of methanolic extracts against fungal and bacterial pathogens that affects food crops, African Journal of Food Science, 2018; 12(5):115- 125. DOI: 10.5897/AJFS2016.1503
Verma M, Kumar A, Antimicrobial and antioxidant activity of whole plant extracts of Bacopa monnieri (l.) Pennell, International Journal of Applied Biology and Pharmaceutical Technology, 2017; 8(2):74-79. DOI: 10.21276/Ijabpt
Haque SKM, Chakraborty A, Dey D et al., Improved micropropagation of Bacopa monnieri (L.) Wettst. (Plantaginaceae) and antimicrobial activity of in vitro and ex vitro raised plants against multidrug-resistant clinical isolates of urinary tract infecting (UTI) and respiratory tract infecting (RTI) bacteria, Clinical Phytoscience 2017; 3(17):1-10. DOI 10.1186/s40816-017-0055-6
Mehmood S, Gull S, Mushtaq A et al., In vitro antibacterial and antioxidant activities of Santalum album and cymbopogon by sequential extraction, The Professional Medical Journal, 2019; 26(5):717-722. DOI: 10.29309/TPMJ/2019.26.05.3462
Singh HK, Charan AA, Charan AI et al., Antifungal and antibacterial activity of methanolic, ethanolic and acetonic leaf extracts of sarpagandha (Rauwolfia serpentine), Journal of Pharmacognosy and Phytochemistry, 2017; 6(5):152-156.
Kalita C, Saikia A, Sarma A et al., Antibacterial and antifungal property of three plants against oral microbes, Journal of Mahatma Gandhi Institute of Medical Sciences, 2018; 23:73-6. DOI: 10.4103/jmgims.jmgims_4_16
Das MK, Mandal M, Mandal S, Assessment of bacterial growth inhibition property and phytochemical analysis of Ocimum sanctum L. leaf extract, International Research Journal of Pharmacy, 2017; 8(7):46-51. DOI: 10.7897/2230-8407.087116
Külcü DB, Gökışık CD, Aydın S, An Investigation of Antibacterial and Antioxidant Activity of Nettle (Urtica dioica L.), Mint (Mentha piperita), Thyme (Thyme serpyllum) and Chenopodium album L. Plants from Yaylacık Plateau, Giresun, Turkey, Turkish Journal of Agriculture - Food Science and Technology, 2019; 7(1):73-80. DOI: 10.24925/turjaf.v7i1.73-80.2123
Qidwai A, Pandey M, Shukla SK et al., Antibacterial activity of Mentha piperita and Citrus limetta against Propionibacterium acnes (anaerobic bacteria), International Journal of Pharmaceutical Sciences and Research, 2016; 7(7):2917-24. DOI: 10.13040/IJPSR.0975-8232.7 (7).2917- 24.
Zubair MF, Atolani O, Ibrahim SO et al., Chemical constituents and antimicrobial properties of Phyllanthus amarus (Schum & Thonn), Bayero Journal of Pure and Applied Sciences, 2017; 10(1):238 – 246. DOI: 10.4314/bajopas.v10i1.35
Sikdar S, Roy S, Banu TN, Phytochmical analysis and antibacterial property assessment of helencha (Enhydra fluctuans; Family: Asteraceae) extracts, GSC Biological and Pharmaceutical Sciences, 2020; 12(02):136-142. DOI: 10.30574/gscbps.2020.12.2.0252
Sircar B, Mandal S, Screening of Elaeocarpus floribundus fruit extracts for bioactive phytocomponents and antibacterial activity against food-borne bacteria. International Journal of Research in Medical Sciences, 2017; 5(8):3665-3671. DOI: 10.18203/2320-6012.ijrms20173582
Das MK, Mandal S, Syzygium cumini and Mangifera indica seed extracts: In Vitro assessment for antibacterial activity alone and in combination with antibiotics against clinical bacteria. Journal of Infectious Diseases & Preventive Medicine, 2016; 4(1):129. DOI: 10.4172/2329- 8731.1000129
Banu TN, Mandal S, Antibacterial activity of Pomegranate (Punica granatum) fruit peel extracts against antibiotic resistant gram-negative pathogenic bacteria, Bioscience Biotechnology Research Communications, 2019; 12(4):1141-1149. DOI: 10.21786/bbrc/12.4/38
Kaho ZM, Kadum AR, Hadi AA. Evalution of antibacterial activity of Piper nigrum extract against Streptococcus mutans and Escherichia coli. Journal of Pharmaceutical Sciences and Research, 2019; 11(2):367-370.
Sreejai R, Raju A, Benchamin D et al., Comparative study of anti-microbial and phytochemical analysis of Piper longum and Piper nigrum, The Pharma Innovation Journal, 2019; 8(3):224-226.
Mandal M, Mandal S, Can Bacteriocins Curb the Emergence of Antibiotic Resistant Pathogenic Bacteria in the Globe?, Current Trends in Biomedical Engineering & Biosciences, 2018; 17(3):555964. DOI: 10.19080/CTBEB.2018.17.555964.
Mahmoudi et al., Adhesion Properties of Probiotic Lactobacillus Strains Isolated from Tunisian Sheep and Goat Milk, Journal of Agriculture, Science and Technolog, 2019; 21(3):587-600
Kazemipoor et al., Screening of antibacterial activity of lactic acid bacteria isolated from fermented vegetables against food borne pathogens, Archives Des Sciences, 2012; 65(6):192-201.
Duangjitcharoen Y, Kantachote D, Ongsakul M, et al., Selection of Probiotic Lactic Acid Bacteria Isolated from Fermented Plant Beverages. Pakistan Journal of Biological Sciences, 2008;11:652-655. DOI: 10.3923/pjbs.2008.652.655
Cotar et al., Quantitative real-time PCR study of the influence of probiotic culture soluble fraction on the expression of Pseudomonas aeruginosa quorum sensing genes, 2010; 69(4).
Chu et al., isolation and characterization of new potential probiotic bacteria based on quorum-sensing system, Journal of Applied Microbiology, DOI: 10.1111/j.1365-2672.2010.04872.x
Besser et al., Impact of probiotics on pathogen survival in an innovative human plasma biofilm model (hpBIOM), Journal of Translational Medicine, 2019; 7:243, DOI: 10.1186/s12967-019-1990-4
Akbar A, Sadiq MB, Ali I, et al., Lactococcus lactis subsp. lactis isolated from fermented milk products and its antimicrobial potential, CyTA - Journal of Food, 2019; 17(1):214-220, DOI:10.1080/19476337.2019.1575474
Alang et al., Identification of lactic acid bacteria as antimicrobial from milk Toraja Belang buffalo, International Conference on Green Agro-industry and Bioeconomy, DOI:10.1088/1755-1315/230/1/012092
Halder et al., Indigenous Probiotic Lactobacillus Isolates Presenting Antibiotic like Activity against Human Pathogenic Bacteria, Biomedicines, 2017; 5(31) DOI: 10.3390/biomedicines5020031
Halder D, Mandal S, Insights into the antagonism of Lactobacillus fermentum curd isolate against Gram-positive and Gram-negative pathogenic bacteria, Bioscience Biotechnology Research Communications, 2018; 11(3):461-468.
Patel A, Lindström C, Patel A, Prajapati J, Holst O, Probiotic properties of exopolysaccharide producing lactic acid bacteria isolated from vegetables and traditional Indian fermented foods. Internationa Journal of Fermented Foods, 2012; 1(1):87-101.
Cusimano MG, Spinello A, Barone G et al., A Synthetic derivative of antimicrobial peptide Holothuroidin 2 from Mediterranean Sea Cucumber (Holothuria tubulosa) in the control of Listeria monocytogenes, Marine Drugs, 2019; 17(159):1-11. DOI: 10.3390/md17030159
El-Sayed M, Awad S, Milk Bioactive Peptides: Antioxidant, Antimicrobial and Anti- Diabetic Activities, Advances in Biochemistry, 2019; 7(1):22-33. DOI: 10.11648/j.ab.20190701.15
Mandal SM, Silva ON, Franco OL, Recombinant probiotics with antimicrobial peptides: a dual strategy to improve immune response in immunocompromised patients, Drug Discovery Today, 2014; 19(8):1045-1050. DOI: 10.1016/j.drudis.2014.05.019
Ahmed TAE, Hammami R, Recent insights into structure–function relationships of antimicrobial peptides, Journal of Food Biochemistry, 2019; 43:e12546. DOI: 10.1111/jfbc.12546
Farhana et al., Isolation of Antimicrobial Peptide from Food Protein Hydrolysates: An Overview, Key Engineering Materials, 2019; 797:168-176.
Pottanat et al., Analysis of the Ribonuclease A Superfamily of Antimicrobial Peptides in Patients Undergoing Chronic Peritoneal Dialysis, Scientific reports, 2019; 9:7753 DOI: 10.1038/s41598-019-44219-x
Ferchichi M, Frere J, Mabrouk K et al. Lactococcin MMFII, a novel class IIa bacteriocin produced by Lactococcus lactis MMFII, isolated from a Tunisian dairy product. FEMS Microbiology Letters, 2001; 205:49–55.
Gong HS, Meng XC, Wang H, Mode of action of plantaricin MG, a bacteriocin active against Salmonella typhimurium, Journal of Basic Microbiology, 2010; 50(1):37–45. DOI 10.1002/jobm.201000130
Arumugam V, Venkatesan M, Ramachandran K et al., Purification, characterization and antibacterial properties of peptide from marine Ascidian Didemnum sp. International Journal of Peptide Research and Therapeutics, 2019; 26:201-208. DOI: 10.1007/s10989-019-09829-z
Freitas et al., Encrypted antimicrobial and antitumoral peptides recovered from a protein rich soybean (Glycine max) by-product, Journal of Functional Foods, 2019; 54:187–198.
Gao et al., Identification and antimicrobial activity evaluation of three peptides from laba garlic and the related mechanism, Food & Function, DOI:10.1039/c9fo00236g
Li B, Lyu P, Xie S et al., LFB: A Novel Antimicrobial Brevinin-Like Peptide from the Skin Secretion of the Fujian Large Headed Frog, Limnonectes fujianensi, Biomolecules, 2019; 9(242):1-13. DOI: 10.3390/biom9060242
Fesenko I, Azarkina R, Kirov I et al., Phytohormone treatment induces generation of cryptic peptides with antimicrobial activity in the Moss Physcomitrella patens, BMC Plant Biology, 2019; 19(9):1-16. DOI: 10.1186/s12870-018-1611-z
Samriti, Biswas R, Biswas K, Antibacterial activity of antimicrobial peptide extracted from Trianthema portulacastrum Leaves, The Pharma Innovation Journal, 2019; 8(3):81-86.
Alexander P, Oyama L, Huws S, Utilising novel antimicrobial peptides isolated from the rumen microbiome as a treatment method for Acinetobacter baumannii, Queen’s University Belfast. Access Microbiology, 2019; 1(1A):1. DOI: 10.1099/acmi.ac2019.po0043
Rončević T, Krce L, Gerdol M et al., Membrane-active antimicrobial peptide identified in Rana arvalis by targeted DNA sequencing. Biochimica et Biophysica Acta (BBA) – Biomembranes, 2018; 1861(3):651-659. DOI: 10.1016/j.bbamem.2018.12.014