Drug-resistant Bacterial Pathogens Research Articles

Clinicoradiological correlation of Endotracheal secretion culture in each case of suspected VAP: a need of the present to combat drug-resistance

Background: Ventilator-associated pneumonia (VAP) in intensive care unit (ICU)-admitted patients is a life-threatening event, caused by a diverse range of microbes having varied susceptibility to different classes of antibiotics. Materials and Methods: We enrolled patients admitted in trauma ICU on mechanical ventilation for >48 h. Modified clinical pulmonary infection score (≥6) having a significant bacterial count (≥105 cfu/ml) in endotracheal (ET) secretions was used to diagnose VAP. Subsequently, we did antibiotic susceptibility testing by the modified Kirby–Bauer method, and the results were interpreted per Clinical and Laboratory Standards Institute guidelines. Results: We enrolled 389 patients in this study. Amongst these, we noted VAP events in 87 patients with an incidence of 15.62/1000 days of ventilators. Gram-negative rods were the predominant microbes causing VAP. Acinetobacter baumannii-calcoaceticus complex (n = 30) followed by Klebsiella pneumoniae (n = 27) and Pseudomonas aeruginosa (n = 19) was the predominant isolate. All nine isolated Staphylococcus aureus strains were methicillin-resistant S. aureus (MRSA). About 48.72% (38/78) of the Gram-negative microbes were meropenem sensitive. All strains of A. baumanii and P. aeruginosa were sensitive to polymyxin B, whereas all isolated MRSA strains were sensitive to vancomycin and linezolid. In addition, drug-resistant epidemiological important bacterial pathogens were also isolated from ET secretions. Conclusion: VAP is caused by a diverse group of multidrug-resistant microorganisms; however, drug-resistant microbes also colonise the in situ ET tubes. Therefore, accurate diagnosis of VAP and its differentiation from ET tube colonisation is a need of present times as appropriate treatment of actual VAP cases will reduce the burden of drug-resistant microbes in ICU settings.

Antibiotic Potentiators Against Multidrug-Resistant Bacteria: Discovery, Development, and Clinical Relevance.

Antimicrobial resistance in clinically important microbes has emerged as an unmet challenge in global health. Extensively drug-resistant bacterial pathogens have cropped up lately defying the action of even the last resort of antibiotics. This has led to a huge burden in the health sectors and increased morbidity and mortality rate across the world. The dwindling antibiotic discovery pipeline and rampant usage of antibiotics has set the alarming bells necessitating immediate actions to combat this looming threat. Various alternatives to discovery of new antibiotics are gaining attention such as reversing the antibiotic resistance and hence reviving the arsenal of antibiotics in hand. Antibiotic resistance reversal is mainly targeted against the antibiotic resistance mechanisms, which potentiates the effective action of the antibiotic. Such compounds are referred to as resistance breakers or antibiotic adjuvants/potentiators that work in conjunction with antibiotics. Many studies have been conducted for the identification of compounds, which decrease the permeability barrier, expression of efflux pumps and the resistance encoding enzymes. Compounds targeting the stability, inheritance and dissemination of the mobile genetic elements linked with the resistance genes are also potential candidates to curb antibiotic resistance. In pursuit of such compounds various natural sources and synthetic compounds have been harnessed. The activities of a considerable number of compounds seem promising and are currently at various phases of clinical trials. This review recapitulates all the studies pertaining to the use of antibiotic potentiators for the reversal of antibiotic resistance and what the future beholds for their usage in clinical settings.

Atomic-Resolution Structures and Mode of Action of Clinically Relevant Antimicrobial Peptides.

Global rise of infections and deaths caused by drug-resistant bacterial pathogens are among the unmet medical needs. In an age of drying pipeline of novel antibiotics to treat bacterial infections, antimicrobial peptides (AMPs) are proven to be valid therapeutics modalities. Direct in vivo applications of many AMPs could be challenging; however, works are demonstrating encouraging results for some of them. In this review article, we discussed 3-D structures of potent AMPs e.g., polymyxin, thanatin, MSI, protegrin, OMPTA in complex with bacterial targets and their mode of actions. Studies on human peptide LL37 and de novo-designed peptides are also discussed. We have focused on AMPs which are effective against drug-resistant Gram-negative bacteria. Since treatment options for the infections caused by super bugs of Gram-negative bacteria are now extremely limited. We also summarize some of the pertinent challenges in the field of clinical trials of AMPs.

ANTIBIOTICS RESISTANCE AND PLASMID PROFILE OF BACTERIAL PATHOGENS ISOLATED FROM HAIR- DRESSING SALON EFFLUENTS IN BENIN CITY

Hairdressing and beauty salons are classified as personal services establishment and such services may pose potential health concerns to their clients including the risk of infection and sometimes injury. The widespread occurrence of drug resistant bacterial pathogens in hairdressing salons effluents has necessitated the need for regular monitoring of antibiotics susceptibility trends. This study examined the susceptibility pattern and plasmid profile of bacterial isolates from hairdressing salon waste water in three different locations (zones) Benin City. New Benin zone hairdressing salon effluent had the highest heterotrophic bacterial count (6.4 x103 ± 0.4 cfu/ml). Major bacterial isolates isolated from the effluent include Staphylococcus aureus, Bacillus sp. Staphylococcus sp. The physico-chemical analyses showed the mean pH to be 6.3 ± 0.47 which is slightly near neutrality and the mean COD to be 127.33 ± 10.09. Result of the antibiotics susceptibility test done using Augumetin, Ofloxacin, Gentanycin, Nalidixic acid, Cotrimaxozole, Amoxycillin, Nitrofurantoin and Tetracyclin showed that the isolates had 100% resistance to Augumentin, Nalidixic acid and Cotrimaxozole. The plasmid profile of the isolates revealed absence of plasmid giving hundred percent conviction that the resistant gene in these organisms are possible located on their chromosomal genome not plasmid oriented.

Synthesis, antimicrobial evaluation and molecular modeling studies of novel thiosemicarbazides/semicarbazides derived from p-aminobenzoic acid

The development of novel antimicrobial agents is critical to combat life-threatening drug-resistant bacterial and fungal pathogens. In the present study, a new series of p-aminobenzoic acid (PABA) derivatives carrying thiosemicarbazide/semicarbazide moiety were designed, synthesized, and studied for their antimicrobial activity. The target molecules (3a–f, 4a–f) were achieved by the reaction of 4-aminobenzohydrazide, obtained from PABA, and various phenyl isothiocyanates/isocyanates. Following structural characterization by spectroscopic methods (1H NMR, 13C NMR, FT-IR, and LC-MS analyses), the synthesized compounds were tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, Candida albicans, and their clinical isolates. Thiosemicarbazides with lipophilic substituents on the phenyl ring were identified as the most active compounds in this series. Among the studied molecules, compound 3e, thiosemicarbazide derivative with trifluoromethyl groups on the phenyl moiety, showed the best antimicrobial activity. Physicochemical parameters of the compounds were computed to predict the drug-likeness of the title compounds. Finally, molecular docking studies were performed in the allosteric binding pocket of ᴅ-alanine:ᴅ-alanine ligase (Ddl) to explain the potential antibacterial activity mechanism of 3e against S. aureus strains.

Comparative Studies to Uncover Mechanisms of Action of N-(1,3,4-Oxadiazol-2-yl)benzamide Containing Antibacterial Agents.

Drug-resistant bacterial pathogens still cause high levels of mortality annually despite the availability of many antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) is especially problematic, and the rise in resistance to front-line treatments like vancomycin and linezolid calls for new chemical modalities to treat chronic and relapsing MRSA infections. Halogenated N-(1,3,4-oxadiazol-2-yl)benzamides are an interesting class of antimicrobial agents, which have been described by multiple groups to be effective against different bacterial pathogens. The modes of action of a few N-(1,3,4-oxadiazol-2-yl)benzamides have been elucidated. For example, oxadiazoles KKL-35 and MBX-4132 have been described as inhibitors of trans-translation (a ribosome rescue pathway), while HSGN-94 was shown to inhibit lipoteichoic acid (LTA). However, other similarly halogenated N-(1,3,4-oxadiazol-2-yl)benzamides neither inhibit trans-translation nor LTA biosynthesis but are potent antimicrobial agents. For example, HSGN-220, -218, and -144 are N-(1,3,4-oxadiazol-2-yl)benzamides that are modified with OCF3, SCF3, or SF5 and have remarkable minimum inhibitory concentrations ranging from 1 to 0.06 μg/mL against MRSA clinical isolates and show a low propensity to develop resistance to MRSA over 30 days. The mechanism of action of these highly potent oxadiazoles is however unknown. To provide insights into how these halogenated N-(1,3,4-oxadiazol-2-yl)benzamides inhibit bacterial growth, we performed global proteomics and RNA expression analysis of some essential genes of S. aureus treated with HSGN-220, -218, and -144. These studies revealed that the oxadiazoles HSGN-220, -218, and -144 are multitargeting antibiotics that regulate menaquinone biosynthesis and other essential proteins like DnaX, Pol IIIC, BirA, LexA, and DnaC. In addition, these halogenated N-(1,3,4-oxadiazol-2-yl)benzamides were able to depolarize bacterial membranes and regulate siderophore biosynthesis and heme regulation. Iron starvation appears to be part of the mechanism of action that led to bacterial killing. This study demonstrates that N-(1,3,4-oxadiazol-2-yl)benzamides are indeed privileged scaffolds for the development of antibacterial agents and that subtle modifications lead to changes to the mechanism of action.

Bioassay Guided Fractionation of Phytocompounds from Bergenia ligulata: A synergistic approach to treat drug resistant bacterial and fungal pathogens

Bergenia ligulata Wall. Engl. is perennial herb used for the treatment urinary discharges, diseases of urinary bladder, dysentery, menorrhagia, splenic enlargement and heart diseases. The aim of the present study was to investigate the antimicrobial and synergistic potential of solvent fractions and major phytocompound of B. ligulata against bacterial and fungal pathogens. The antimicrobial and synergistic potential of the solvent fractions (Petroleum ether, chloroform, ethyl acetate, and remaining aqueous) of methanolic extract of B. ligulata rhizome and major phytocompound bergenin were investigated by agar well diffusion and broth microdilution method. Major Phytocompound bergenin was quantified in solvent fractions of B. ligulata by HPTLC and HP-LC method Molecular docking of bergenin was done by AutoDock vina with bacterial and fungal targets. Drug likeness and ADME screening was done with help of molinspiration and swissADME servers. Ethyl acetate sub-fraction of B. ligulata showed the highest antimicrobial activity against bacterial and fungal strains with zone of inhibition 13, 13, 14, 13 mm against Escherichia coli, Staphylococcus aureus, Candida albicans MTCC 277 and ATCC 90028 respectively. The MIC of ethyl acetate sub-fraction against E. coli, S. aureus, C. albicans MTCC 277 and ATCC 90028 was 31.25, 250, 62.5, 62.5 μg mg−1 respectively. Bergenin major phytocompound of B. ligulata also showed the antimicrobial activity with MIC 250 μg mg−1 against all the selected bacterial and fungal strains. Quantification of bergenin showed that ethyl-acetate sub fraction (17.6 μg mg−1 and 112 μg mg−1 measured through HPTLC and HPLC, respectively) is rich in bergenin content. The bergenin content recovered in ethyl acetate sub-fraction is 38.2%. Bergenin showed good interactions with bacterial and fungal targets and follows all parameters of drug likeness. Conclusions: Solvent fractions of B. ligulata and major phytocompound Bergenin can be used as a bioenhancer of antibacterial and antifungal agents to treat drug resistant pathogens.

Magnitude of Drug-Resistant Gram-Positive Bacterial Pathogens, and Its Associated Factors from External Ocular Infected Patients Attending at Jinka General Hospital Ophthalmic Clinic, Southern Ethiopia.

BackgroundThe emergence and the incidence of antimicrobial-resistant Gram-positive bacteria increase the risk of treatment failure of ocular infection. Thus, this study aimed to determine the magnitude of drug-resistant Gram-positive bacterial pathogens and associated factors among patients attending Jinka General Hospital Ophthalmic Clinic in Southern Ethiopia.MethodsA facility-based cross-sectional study was conducted on 347 external ocular infected patients attending Jinka General Hospital Ophthalmic Clinic from 15th March to 20th June 2021. Study participants were selected by a systematic random sampling technique. Required data were collected by using structured questionnaires. Swabs of the external eye were obtained with a sterile cotton swab and processed in the Jinka branch Public Health Laboratory. Each sample was inoculated on blood agar, chocolate agar, and mannitol salt agar and incubated aerobically and micro-aerobically at 37°C for 48 hrs. Identification was done by standard microbiological protocols and antimicrobial resistance testing by Kirby Bauer’s disk diffusion technique. Logistic regression was used to identify the associated factors with Gram-positive bacterial external-ocular infection.ResultsThe overall prevalence of Gram-positive bacterial pathogens among external ocular samples was 119/347 (34.3%). S. aureus 57/119 (47.39%), followed by coagulase-negative Staphylococcus spp. 38/119 (31.9%), and S. pneumoniae 13/119 (10.9%) were predominantly isolated. Overall, multi-drug resistance was observed in 72/119 (60.5%) of the bacteria isolates. The 78.9% of isolated S. aureus were MDR. Methicillin-resistant S. aureus (MRSA) and Methicillin-resistant CoNS (MR-CoNS) were accounted for 45.6% and 36.8%, respectively. Previous use of ocular antibiotics was statistically associated to external-ocular Gram-positive bacterial infection [AOR= 1.624, 95% CI: (1.037–2.542)].ConclusionHigh levels of drug resistance were observed for commonly prescribed antibiotics, which attracted the attention of an ophthalmic clinic. Thus, for the effective treatment and management of bacterial eye infections, regular monitoring of drug resistance trends is essential.

Molecular Characterization of WCK 5222 (Cefepime/Zidebactam)-Resistant Mutants Developed from a Carbapenem-Resistant Pseudomonas aeruginosa Clinical Isolate.

ABSTRACTWCK 5222 (cefepime/zidebactam) is a β-lactam/β-lactamase inhibitor combination that is effective against a broad range of highly drug-resistant bacterial pathogens, including those producing metallo-β-lactamase. In this study, we isolated a multidrug-resistant Pseudomonas aeruginosa clinical strain that is resistant to a variety of β-lactam antibiotics and the ceftazidime-avibactam combination. A metallo-β-lactamase gene blaDIM-2 was identified on a self-transmissible megaplasmid in the strain, which confers the resistance to β-lactam antibiotics, leaving WCK 5222 potentially one of the last treatment resorts. In vitro passaging assay combined with whole-genome sequencing revealed mutations in the pbpA gene (encoding the zidebactam target protein PBP2) in the evolved resistant mutants. Among the mutations, a V516M mutation increased the bacterial virulence in a murine acute pneumonia model. Reconstitution of the mutations in the reference strain PAO1 verified their roles in the resistance to zidebactam and revealed their influences on cell morphology in the absence and presence of zidebactam. Microscale thermophoresis (MST) assays demonstrated that the mutations reduced the affinity between PBP2 and zidebactam to various extents. Overall, our results revealed that mutations in the pbpA gene might be a major cause of evolved resistance to WCK 5222 in clinical settings.IMPORTANCE Antibiotic resistance imposes a severe threat on human health. WCK 5222 is a β-lactam/β-lactamase inhibitor combination that is composed of cefepime and zidebactam. It is one of the few antibiotics in clinical trials that are effective against multidrug-resistant Pseudomonas aeruginosa, including those producing metallo-β-lactamases. Understanding the mechanisms and development of bacterial resistance to WCK 5222 may provide clues for the development of strategies to suppress resistant evolvement. In this study, we performed an in vitro passaging assay by using a multidrug-resistant P. aeruginosa clinical isolate. Our results revealed that mutations in the zidebactam target protein PBP2 play a major role in the bacterial resistance to WCK 5222. We further demonstrated that the mutations reduced the affinities between PBP2 and zidebactam and resulted in functional resistance of PBP2 to zidebactam.

Green synthesis of silver nanoparticles by Pisum sativum L. (pea) pod against multidrug resistant foodborne pathogens

The consumption of foods contaminated with various foodborne organisms such as, viruses, fungi and bacteria are recognized as the important sources of foodborne illness in animals and humans. Multidrug resistant foodborne bacteria increased morbidity, mortality rates, and severe economic loss and associated with prolong hospitalization. The development of natural and novel antibacterial agent is much needed as there is an increasing concern on multidrug resistant bacteria. This study aimed to synthesize silver nanoparticles using aqeous Pisum sativum L. (pea) pod extract and to characterize the nanoparticles. It was further used on various drug resistant foodborne bacterial pathogens and antimicrobial activity was determined. The synergistic antibacterial activity, antioxidant activity and biocompatibility were also assessed. Green synthesized nanoparticles applied in this study were synthesized using aqueous P. sativum L. (pea) pod extract with particle size 30 nm. The green synthesized silver nanoparticles showed antimicrobial activity against Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 700802, Streptococcus gordonii ATCC 49818, Staphylococcus aureus (MRSA) ATCC 4330 and Staphylococcus aureus ATCC 25923. Among the pathogenic bacterial strains, silver nanoparticles were highly active against S. aureus ATCC 25923 than other bacterial strains (22 ± 2 mm). The antibacterial activity varied between 15 ± 2 mm and 22 ± 2 mm diameter zone of inhibition. The MIC value of the nanoparticles ranged from 6.25 µg/mL to 75 µg/mL and MBC value ranged from 50 µg/mL to 150 µg/mL. The green synthesized nanoparticles showed antioxidant potential. Normal fibroblast cell lines (L-929) was used to test the cytotoxic activity and the increased IC50 value (750.5 ± 5.5 μg/mL) indicated good biological compatibility. The present findings revealed that green synthesized silver nanoparticles exhibited potent activity against various food borne pathogenic bacteria. These nanoparticles might be well developed as novel antibacterial substances for the treatment of food borne multidrug resistant bacterial infection.

LANTIBIOTICS OF MILK ISOLATES: A SHORT REVIEW ON CHARACTERIZATION AND POTENTIAL APPLICATIONS

Milk, due to its high nutritional content, is an excellent medium for supporting growth of diverse group of microorganisms, many of which produce beneficial compounds like bacteriocins. Class I bacteriocins, called lantibiotics, are ribosomally synthesized, post-translationally modified peptides containing unusual amino acids, such as dehydrated and lanthionine residues with antibacterial activities. Bacterial strains isolated from milk and dairy products produce a range of lantibiotics which can employed for development of food preservatives, flavor enhancers and as alternate treatment strategies for multi drug resistant bacterial pathogens. The diverse category of lantibiotics from milk isolates include well characterized prototypes like nisin to newer peptides yet to be studied. In this review, details of most prominent lantibiotics obtained from milk isolates have been presented with special focus on applications of these lantibiotics in therapeutics and food.

FTIR Spectroscopy for Identification Aspergillus fumigatus Secondary Metabolites Extract against Multi Drugs Resistance Bacteria Isolated from surgical Site wound Infection

In the current scenario Multi Drug Resistant (MDR) bacterial pathogens are increasing very rapidly due to the misuse of antibiotics to control antibiotic resistance, we need to know the current pattern of antibiotic resistance. Furthermore, new bioactive metabolites are needed for the alternative option to control antibiotic resistance. Fungi have the ability to produce potent metabolites. The production of secondary metabolites such as antimicrobial agents is the most important property of fungi. Antimicrobial activity of extract were noted against different pathogenic (Clinical Isolates) and using agar well diffusion assay method and noted different zone of inhibition of each bacteria, wells were loaded with different concentration’s 50 µL and 100 µL. Maximum zone of inhibition were reported at different concentration of different bacteria. Ethyl acetate crude extract at 50 µL concentration’s 17 ± 0.15 mm, 18 ± 0.1 mm , 16 ± 0.4 mm, 19 ± 0.26 mm, 17 ± 0.30 mm,16 ± 0.36 mm, zone of inhibition against E.coli sp, Pseudomonas, Klebsiella sp Proteus sp, S,aureus, , and Salmonella sp, respectively. While in 100 µL zone of inhibition was noted, 21 ± 0.15 mm, 22 ± 0.40 mm, 20 ± 0.35 mm, 21 ± 0.26 mm, 22 ± 0.45 mm 19 ± 1.10 mm zone of inhibition against E.coli sp, Pseudomonas, Klebsiella sp Proteus sp, S,aureus, , and Salmonella sp, respectively. In the current study we used FTIR and Plasmon Resonance (SPR) UV-visible spectroscopy observed at 408 nm during UV-visible spectroscopy. FTIR analysis revealed the involvement of phenolic, carboxyl and hydroxyl groups in reduction of Ag+ ions to form fungal metabolites while stabilization components of were fungal metabolites amide linkage and amino acid. Keywords; Aspergillus fumigatus, Secondary metabolites, Ethyl acetate, FTIR, UV-visible spectroscopy, MDR pathogen.

Physicochemical and microbial pollution of a reservoir in South India and role of bacteriophage treatment to curtail drug-resistant bacterial pollution in water

This study aimed to assess the physicochemical and microbiological pollution of water samples collected from Bellandur Lake, Bengaluru, South India, and to study the potential of bacteriophage treatment to curtail drug-resistant bacterial pathogens. The water samples were collected from the lake during four time periods in 2018–19. The physicochemical, heavy metal, and bacteriological analyzes were studied by standard protocol. The antibiotic sensitivity profiles of the major isolates from the water samples were assessed by disk diffusion assay, and two isolates that showed resistance to the highest percentage of the tested antibiotics were characterized by 16S rRNA gene sequencing. The lake water samples were treated with the isolated bacteriophages with controls, and the reduction of viable bacterial count in the treated water samples was estimated. This study revealed that the physicochemical, heavy metal and microbiological qualities of water samples were exceeded the permissible limits set by the standard authorities ( p ≤ 0.05). When tested against 44 antibiotics, most of the isolates were found to be multidrug-resistant in which IS1 and IS2 showed resistance to the highest percentage of antibiotics, which were confirmed to be Pseudomonas aeruginosa strain DSCEbt-Bellandur01 and Pseudomonas sp. strain DSCEbt-Bellandur022, respectively. When the lake water samples were treated with the isolated bacteriophages, the study showed a 99.99 % reduction in the viable bacterial count (CFUL/ml) when compared to untreated water samples ( p ≤ 0.05). Thus, the present study suggests that bacteriophage-based therapy is one of the promising approaches to treat various water bodies to reduce microbial pollution, and the approach can be used to curtail the emergence of multi-drug resistant pathogens in the water samples. • Assessing the physicochemical and microbial pollution of lake water in South India. • Bacteriophage therapy as a potential approach in reducing MDR pathogens in water. • Lake water quality found to be poor with heavy metal and MDR bacterial pathogens. • IS1 and IS2 belonged to Pseudomonas spp. and showed 100 % antibiotic resistance. • 99.9 % reduction of CFU/ml in the treated samples with isolated bacteriophage.

Immunoadjunctive Therapy against Bacterial Infections Using Herbal Medicines Based on Th17 Cell-mediated Protective Immunity.

One of the major health concerns in the world is the global increase in intractable bacterial infectious diseases due to the emergence of multi- and extensively drug-resistant bacterial pathogens as well as increase in compromised hosts around the world. Particularly, in the case of mycobacteriosis, the high incidence of tuberculosis in developing countries, resurgence of tuberculosis in industrialized countries, and increase in the prevalence of Mycobacterium avium complex infections are important worldwide health concerns. However, the development of novel antimycobacterial drugs is currently making slow progress. Therefore, it is considered that devising improved administration protocols for clinical treatment against refractory mycobacteriosis using existing chemotherapeutics is more practical than awaiting the development of new antimycobacterial drugs. The regulation of host immune responses using immunoadjunctive agents may increase the efficacy of antimicrobial treatment against mycobacteriosis. The same situations also exist in cases of intractable infectious diseases due to common bacteria other than mycobacteria. The mild and long-term up-regulation of host immune reactions in hosts with intractable chronic bacterial infections, using herbal medicines and medicinal plants, may be beneficial for such immunoadjunctive therapy. This review describes the current status regarding basic and clinical studies on therapeutic regimens using herbal medicines, useful for the clinical treatment of patients with intractable bacterial infections. In particular, we focus on immunoadjunctive effects of herbal medicines on the establishment and manifestation of host antibacterial immunity related to the immunological roles of Th17 cell lineages.

Review LANTIBIOTICS OF MILK ISOLATES: A SHORT REVIEW ON CHARACTERIZATION AND POTENTIAL APPLICATIONS

Milk, due to its high nutritional content, is an excellent medium for supporting growth of diverse group of microorganisms, many of which produce beneficial compounds like bacteriocins. Class I bacteriocins, called lantibiotics, are ribosomally synthesized, post-translationally modified peptides containing unusual amino acids, such as dehydrated and lanthionine residues with antibacterial activities. Bacterial strains isolated from milk and dairy products produce a range of lantibiotics which can employed for development of food preservatives, flavor enhancers and as alternate treatment strategies for multi drug resistant bacterial pathogens. The diverse category of lantibiotics from milk isolates include well characterized prototypes like nisin to newer peptides yet to be studied. In this review, details of most prominent lantibiotics obtained from milk isolates have been presented with special focus on applications of these lantibiotics in therapeutics and food.

A promising Natural remedy for Resistant Bacteria Associated Diarrhea from Mangifera indica. L

We examine the antibacterial activity of Mangifera indica.L against the drug resistant bacterial pathogens. The Indian traditional mango fruit exposed promise in the prevention of diarrhea. However, there is less information existing regarding activity against drug resistance bacteria causing diarrhea. In this study, we performed isolation and identification of bacterial pathogens from diarrheal stool samples and analyzed their antibiotic resistance pattern with three generation antibiotics. Antibiotic activity of mango kernel exhibited remarkable activity from 15.2±0.5mm to 19.0±0.3mm zone of inhibition. MIC of kernel extract was noted as 10 μg /ml. Current study provide the potent antibacterial activity of mango kernel against the drug resistant bacteria. In conclusion, the traditional Indian fruit become the natural remedy for the treatment of diarrhea.

Coumarin Exhibits Broad-Spectrum Antibiofilm and Antiquorum Sensing Activity against Gram-Negative Bacteria: In Vitro and In Silico Investigation.

Quorum sensing (QS) and biofilm inhibition are recognized as the novel drug targets for the broad-spectrum anti-infective strategy to combat the infections caused by drug-resistant bacterial pathogens. Many compounds from medicinal plants have been found to demonstrate anti-infective activity. However, broad-spectrum anti-QS and antibiofilm efficacy and their mode of action are poorly studied. In this study, the efficacy of coumarin was tested against QS-regulated virulent traits of Gram-negative bacteria. Coumarin inhibited the production of violacein pigment in Chromobacterium violaceum 12472 by 64.21%. Similarly, there was 87.25, 70.05, 76.07, 58.64, 48.94, and 81.20% inhibition of pyocyanin, pyoverdin, and proteolytic activity, lasB elastase activity, swimming motility, and rhamnolipid production, respectively, in Pseudomonas aeruginosa PAO1. All tested virulence factors of Serratia marcescens MTCC 97 were also suppressed by more than 50% at the highest sub-minimum inhibitory concentration. Moreover, the biofilms of bacterial pathogens were also inhibited in a dose-dependent manner. Molecular docking and molecular dynamics (MD) simulation gave insights into the possible mode of action. The binding energy obtained by docking studies ranged from −5.7 to −8.1 kcal mol–1. Coumarin was found to be docked in the active site of acylhomoserine lactone (AHL) synthases and regulatory proteins of QS. MD simulations further supported the in vitro studies where coumarin formed a stable complex with the tested proteins. The secondary structure of all proteins showed a negligible change in the presence of coumarin. Computational studies showed that the possible mechanisms of anti-QS activity were the inhibition of AHL synthesis, antagonization of QS-regulatory proteins, and blocking of the receptor proteins. The findings of this study clearly highlight the potency of coumarin against the virulence factors of Gram-negative bacterial pathogens that may be developed as an effective inhibitor of QS and biofilms.

Antimicrobial efficacy and activity of ethanolic extract of Piper betle L. on Staphylococcus aureus-infected wound in mice and clinical isolates of multiple drug-resistant bacterial pathogens.

This study aimed to determine the in vivo effectiveness of the ethanolic extract of Piper betle L. leaves against Staphylococcus aureus-infected wounds in mice and its antimicrobial properties on clinical isolates of multiple drug-resistant bacterial pathogens. Twenty mice were divided into four groups. Wounds were created in all mice under anesthesia by excision from the dorsal skin down to the subcutaneous fat and inoculating with S. aureus. After 24 h, the wound of each mouse was treated once daily by application of the respective cream. Group I was treated with mupirocin antibacterial cream; Group II received a cream base containing no active ingredient; Groups III and IV were treated with 2.5% and 5.0% concentrations of P. betle cream, respectively. Further, an in vitro study was performed by adding undiluted, 1:50 and 1:100 dilutions of the four studied creams in normal saline containing 1.5 × 108 CFU/mL of the following bacteria: antimicrobial-susceptible S. aureus, Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant S. aureus, extended-spectrum β-lactamase-producing Escherichia coli, vancomycin-resistant Enterococcus, metallo-βlactamase-producing P. aeruginosa and carbapenem-resistant Klebsiella pneumoniae. The mice in Groups III and IV had significantly faster wound contraction and significantly shorter reepithelialization time than Group II (p < 0.05), which were not significantly different from Group I (p > 0.05). P. betle creams inhibited all studied bacterial strains at full concentration and at a dilution of 1:50. The inhibitory effect was more significant than Groups I and II (p < 0.05), except on S. aureus. Specifically, S. aureus inhibition was not significantly different for Groups III and IV (p > 0.05) when compared with Group I. Cream formulations derived from P. betle ethanolic extract have great potential as antimicrobial agents for the treatment of wound infection. Further clinical tests are recommended to determine the safety and efficacy of these formulations in other mammalian species.

Cloning and expression analysis of fused holin-endolysin from RL bacteriophage; Exhibits broad activity against multi drug resistant pathogens

Antibiotic resistance has become a major risk to community health over last few years because of antibiotics overuse around the globe and lack of new antibiotics development. Phages and their lytic enzymes are considered as an effective alternative of antibiotics to control drug resistant bacterial pathogens. Endolysins prove to be a promising class of antibacterials due to their specificity and less chances of resistance development in bacterial pathogens. Though large number of endolysins has been reported against gram positive bacteria, very few reported against gram negative bacteria due to the presence of outer membrane, which acts as physical barrier against endolysin attack to peptidoglycan. In the current study, we have expressed endolysin (RL_Lys) and holin fused at the N terminus of endolysin (RL_Hlys) from RL phage infecting multi drug resistant (MDR) Pseudomonas aeruginosa. Both endolysin variants were found active against wide range of MDR strains P. aeruginosa, Klebsella pneumonia, Salmonella Sp. and Methicillin Resistant Staphylococcus aureus (MRSA). Broth reduction assay showed that RL_Hlys is more active than RL_Lys due to presence of holin, which assist the endolysin access towards cell wall. The protein ligand docking and molecular dynamic simulation results showed that C- terminus region of endolysin play vital role in cell wall binding and even in the absence of holin, hydrolyze a broad range of gram negative bacterial pathogens. The significant activity of RL-Lys and RL_Hlys against a broad range of MDR gram negative and positive bacterial pathogens makes them good candidates for antibiotic alternatives.

Isolation and Identification of Multiple Drug Resistant Bacterial Pathogens from Well Water Samples in and Around Wolaita Sodo Town, Southern Ethiopia

Water for human consumption is required to be free from any bacteria that might pose a health risk. The worldwide prevalence of pathogen contamination is a serious concern, and enhancing the understanding of major pathogen sources and their significant impacts on water resources is crucial. Further, these organisms underwent multiple drug resistance in their systems. The present study mainly focused on Multiple Drug Resistant (MDR) bacterial pathogens in well water system in and around Wolaita Sodo Town. A total of 380 well water samples were collected and screened for SPC, enrichment process and selective media isolation. Further all the isolates were used to know the sensitivity/resistant patterns by Bauer-Kirby method and based on resistant pattern MDR isolates were assessed and recorded. Amon 380 well water samples screened for water potability by SPC method, 154 samples were positive. Among 154 SPC positive water samples yielded 106 different isolates of bacteria and it includes five genera, namely Escherichia coli, Salmonella spp., Shigella spp., Proteus spp. and Enterococcus spp. All the isolated five genus were confirmed by preliminary characters, colony morphology and biochemical tests. Among 106 isolates, 13 isolates of E. coli, 3 isolates of Salmonella spp., 21 isolates of Shigella spp., 9 isolates of Proteus spp., and 4 isolates of Enterococcus spp. were documented as MDR bacterial pathogens. The high prevalence rate of multiple drug resistant bacterial pathogens in the well water samples could potentially pose a threat to people consuming this water. Therefore, the present study suggesting to monitor the quality of water and strict quality control measures should be put in place to ensure the effective treatment of drinking water.&#x0D; Keywords: Water samples, Standard Plate Count, Antibacterial Susceptibility Test and MDR