Carbapenem resistance among Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital in south India

Genotypic Characterisation of Carbapenem-Resistant Enterobacteriaceae in a Tertiary Care Hospital in South India

Introduction The antimicrobial resistance of Enterobacteriaceae is variable and is influenced by both geographic location and regional antibiotic use. The overuse of antibiotics, especially in hospitalised patients, suppresses the growth and persistence of drug-resistant bacteria. This study aimed to detect the prevalence of carbapenem-resistant Enterobacteriaceae and the genes responsible for the resistance. Methods A cross-sectional study has been conducted over the course of two years, from October 2021 to September 2023. A total of 2,152 samples, including pus, blood, urine, sputum and various body fluids, were collected and subjected to study. All data were analysed and presented as frequency with percentage. Results Out of 2,152 samples, 659 (32.1%) samples showed growth. Among them, 250 (38%) were found to be Enterobacteriaceae, of which 22 (8.8%) were resistant to carbapenems. The isolates were Escherichia coli (nine, 40%) followed by Klebsiella pneumoniae (eight, 36%), Morganella morganii (two, 9%), Klebsiella oxytoca (one, 5%), Proteus vulgaris (1, 5%), and Enterobacter cloacae (1, 5%). NDM (14, 63.63%) was the most common gene detected from the isolates. Conclusion Our research leads us to the conclusion that resistance to carbapenem medication can result from either the generation of carbapenemase or from non-carbapenemase mechanisms like loss of porin channels or an increase in the efflux pump. According to our research, the primary source of carbapenem resistance is metallo-β-lactamase. Therefore, it is critical for all the laboratories to identify the mechanism and incidence of carbapenem resistance in order to support epidemiological research, infection control and antibiotic stewardship.

Colistin Insusceptibility in Carbapenem-Resistant Enterobacteriaceae Isolates From a Tertiary Referral Centre

Background Antimicrobial resistance has developed significant importance as a worldwide health concern more so in the 21st century. This is more specifically observed among the Enterobacteriaceae family, the major group of Gram-negative bacteria. Resistance to carbapenems and colistin antimicrobials from the reserve group, in critical infection treatment poses a substantial therapeutic challenge. This study aims to detect resistance to both carbapenems and colistin in Enterobacteriaceae isolates, emphasizing the importance of monitoring. Materials and methods A laboratory-based study investigated 82 Carbapenem-Resistant Enterobacteriaceae (CRE) isolates from hospitalized patients at Krishna Hospital & Medical Research Centre, Karad, India, for two years (November 2021-November 2023). The Kirby-Bauer disc diffusion method was used to determine the antimicrobial susceptibility following Clinical Laboratory Standards Institute 2022 recommendations. To validate Carbapenem-Resistant Enterobacteriaceae isolates, the Modified Carbapenem Inactivation Method (mCIM) was used, and Colistin resistance was ascertained using Broth Microdilution Susceptibility Testing (BMD). Results Among 309 Enterobacteriaceae isolates, 82 (26.5%) exhibited carbapenem resistance, with 75 confirmed by Modified Carbapenem Inactivation Method (mCIM) testing. For patients in the age group 51-60 years (20%), with men being the most prevalent, the predominance of CRE isolates was from the Intensive Care Unit (44%), mostly from urine samples (34.6%). The most dominant CRE was Klebsiella pneumoniae (62.7%), followed by Escherichia coli (32%). Colistin resistance was found in 14 (18.7%) of CRE isolates, with the highest minimum inhibitory concentration (MIC) at 4 µg/mL (n=10) and 16 µg/mL (n=4). Colistin-resistant isolates (n=10) were sensitive to amikacin (71.4%) and resistant to many antibiotics. Conclusion The extreme rise of colistin-resistant cases among CRE in healthcare settings is a solemn alarm. Among the most effective treatments, aminoglycosides amikacin and netilmicin show the greatest sensitivity against these colistin-resistant CRE infections. The findings stress the difficulties in treating such infections and the dire need for solid antimicrobial stewardship and novel therapeutic strategies.

The crisis of carbapenemase-mediated carbapenem resistance across the human-animal-environmental interface in India

Carbapenems are the decision-making antimicrobials used to combat severe Gram-negative bacterial infections in humans. Carbapenem resistance poses a potential public health emergency, especially in developing countries such as India, accounting for high morbidity, mortality, and healthcare cost. Emergence and transmission of plasmid-mediated "big five" carbapenemase genes including KPC, NDM, IMP, VIM and OXA-48-type among Gram-negative bacteria is spiralling the issue. Carbapenemase-producing carbapenem-resistant organisms (CP-CRO) cause multi- or pan-drug resistance by co-harboring several antibiotic resistance determinants. In addition of human origin, animals and even environmental sites are also the reservoir of CROs. Spillage in food-chains compromises food safety and security and increases the chance of cross-border transmission of these superbugs. Metallo-β-lactamases, mainly NDM-1 producing CROs, are commonly shared between human, animal and environmental interfaces worldwide, including in India. Antimicrobial resistance (AMR) surveillance using the One Health approach has been implemented in Europe, the United-Kingdom and the United-States to mitigate the crisis. This concept is still not implemented in most developing countries, including India, where the burden of antibiotic-resistant bacteria is high. Lack of AMR surveillance in animal and environmental sectors underestimates the cumulative burden of carbapenem resistance resulting in the silent spread of these superbugs. In-depth indiscriminate AMR surveillance focusing on carbapenem resistance is urgently required to develop and deploy effective national policies for preserving the efficacy of carbapenems as last-resort antibiotics in India. Tracking and mapping of international high-risk clones are pivotal for containing the global spread of CP-CRO.

Bacteriological Quality of Table Eggs in Moroccan Formal and Informal Sector

Eggs constitute an important part of the Moroccan diet. However, contaminated eggs can cause a serious public health problem if consumed undercooked, uncooked, or used in unpasteurized egg foodstuffs. This study was carried out to evaluate the microbial contents of eggs according to their sales sector in Morocco. For that, a total of 1770 eggs were collected from January to September 2021 from formal markets (refrigerated eggs from large shopping centers) and informal markets (eggs at ambient temperature from ambulatory sellers, street vendors, kiosks, and neighborhood stores) and transferred to the Avian Pathology Unit at Hassan II Agronomic and Veterinary Institute. The eggshells and their contents were tested separately; swabs of eggshells were used to inoculate Mac-Conkey agar, while the egg contents were cultured on Mac-Conkey and Mannitol salt agar, then standard microbiological tests were performed to identify the isolated organisms. The results showed that informal eggs were more contaminated (87%) than formal eggs (48) (p < 0.05). The bacteria isolated from the eggshells (informal and formal) were Enterobacter agglomerans (59% and 21%), Klebsiella spp. (24% and 4%), Enterobacter cloacae (17% and 8%), E. coli (9% and 1%), Serratia spp. (9% and1%), Pseudomonas aeruginosa (9% and 1%), Shigella spp. (5% and 0%), Salmonella enteritidis (0% and 2%), Proteus spp. (4% and 0%), Enterobacter sakazakii (2% and 0%), Rahnella aquatilis (1% and 0%), and Staphylococcus aureus (0% and 1%). For the egg-contents, the detected bacteria (informal and formal) were Enterobacter agglomerans (14% and 28%), Klebsiella spp. (7% and 6%), Staphylococcus aureus (6% and 1%), Enterobacter cloacae (4% and 4%), E. coli (4%, 1%), Shigella spp. (4%, 0%), Acinetobacter baumannii (3% and 1%), Salmonella enteritidis (2% and 0%), Serratia spp. (1% and 6%), Proteus spp. (1% and 3%), and Enterobacter sakazakii (1% and 0%). We conclude that eggs might be contaminated with several bacteria and can constitute a public health threat in Morocco.

In Vitro Activity of Single and Combined Antibiotics against Carbapenem Resistant Enterobacteriaceae Clinical Isolates in Relation to their Resistance Genes

Background: Mortality due to infection with carbapenem-resistant Enterobacteriaceae (CRE) is reported globally and carbapenemase production is the main mechanism of resistance in these isolates. The detection and treatment of carbapenemase-producing Enterobacteriaceae (CPE) is a major challenge in health care facilities. Objectives: The aim of the current study was to evaluate the in-vitro effect of different single and combined antibiotic agents against CRE clinical isolates. Methodology: Fifty CRE isolates were detected using disk diffusion test as a screening test. Species identification and antibiotic susceptibility testing was done using Vitek 2 system. Carbapenemase enzyme production was confirmed by Carba NP test. Multiplex PCR was done to detect carbapenem resistance genes. Antibiotics were tested in the form of single agents (colistin and tigecycline) and combined (tigecycline/ colistin, doripenem/ colistin and dual carbapenem therapy (ertapenem and doripenem) against CRE isolates using E-test method. Results: Most of the CRE isolates were K. pneumoniae, 68%, followed by E. coli, 22%, S. marcescens, 4%, E. cloacae, 4% and C. freundii, 2%. CPE was confirmed in 46 isolates by multiplex PCR; blaNDM-like was the main carbapenem resistance gene in (84%) of the isolates, followed by blaOXA-48-like (6%) and blaKPC-like (2%). Carba NP test detected 90% of CPE isolates. Single use of colistin and tigecycline showed 100% sensitivity against all tested CRE isolates except in blaNDM-like (83%).  Combination of colistin/tigecycline showed synergetic activity in 18% of CRE that was correlated to their carbapenemase R genes showing a significant increase in blaOXA-48-like and blaKPC-like positive isolates (100%) compared to blaNDM-like (7%). Other combinations showed indifferent effect whereas antagonism was not detected in any of the tested combinations. Conclusions: blaNDM-like is the main carbapenemase-producing gene detected among our CPE isolates followed by blaOXA-48-like. Colistin and tigecycline are still effective when used as single agents, and may offer effective treatment options when used in combination for CRE infections. Characterization of carbapenemases is crucial in determining treatment options. There is urgent demand for the development of novel therapeutic agents against NDM-producing CPE isolates.

Carbapenemase Production and Detection of Colistin-Resistant Genes in Clinical Isolates of Escherichia Coli from the Ho Teaching Hospital, Ghana

Background

Effective and successful treatment of infectious diseases is a significant gain in clinical settings. However, resistance to antibiotics, especially the last-resort medicines, including carbapenems and colistin is on the rise.

Aim

The aim of this study was to detect carbapenemase production and colistin-resistant genes in clinical isolates of Escherichia coli. Method. The study was a cross-sectional study carried out from July 2018 to June 2019. One hundred and thirty-five nonrepetitive E. coli isolates obtained from various clinical samples were screened for carbapenemase production using meropenem (10 μg) and imipenem (10 μg) disks. Screened-positive isolates were further subjected to a confirmatory test using modified carbapenem inhibition method (mCIM). Deoxyribonucleic acid (DNA) was extracted from all the isolates to detect colistin-resistant genes by polymerase chain reaction. Data were analyzed using GraphPad Prism version 8.00 for Windows and IBM SPSS version 26 (IMB Corp. New York, USA).

Results

Of the 135 isolates, 2 were screened positive for carbapenemase production but tested negative to mCIM. With the colistin-resistant genes, only mcr-1 and mcr-2_700bp were detected in 3 of the E. coli isolates, representing 2.2%. The mcr-1 was detected in a high vaginal swab sample of a female aged between 65 and 84 years. Mcr-2_700bp was also detected in urine and blood samples of the patients.

Conclusion

The study investigated the presence of carbapenemase and colistin-resistant genes in E. coli organisms. The absence of carbapenemase in the isolates and the detection of colistin-genes call for strict infection prevention and control practices to prevent their introduction and spread to other bacterial species, respectively.

Comparative Evaluation of Colistin Broth Disk Elution Method With Two Commercially Available Systems for Colistin Susceptibility Testing Against Carbapenem-Resistant Klebsiella pneumoniae: A Single-Center Exploratory Study

Purpose: The purpose is to explore the diagnostic utility of colistin broth disk elution (CBDE) as a simple and reliable method of colistin susceptibility testing.

Materials and methods: An exploratory study was undertaken in a tertiary care teaching hospital in Uttarakhand, from September 2021 to March 2022, after obtaining approval from the Institute Ethics Committee. Twenty-five non-repetitive carbapenem-resistant Klebsiella pneumoniae clinical isolates were included in the study. Matrix‐assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and BD Phoenix M50 system were used to perform species-level identification and antibiotic susceptibility testing (AST), respectively, as per the manufacturer’s instructions. AST results (including those of colistin) were interpreted as per the CLSI guidelines 2022. The test isolates were further subjected to additional in vitro colistin susceptibility testing using a commercially available Mikrolatest colistin susceptibility testing kit and CBDE, respectively.

Results: The in vitro colistin resistance rates varied from 8% by BD Phoenix system to 20% by Mikrolatest kit and 32% by CBDE, respectively. For colistin susceptibility, a higher CA was observed between the BD Phoenix system and CBDE (64.71%) than between the Mikrolatest kit and CBDE (31.60%). Overall, a statistically significant fair agreement was observed between the BD Phoenix system and CBDE (Kappa: 0.312; 95% CI: 0.036 to 0.660) and Mikrolatest MIC colistin kit and CBDE (Kappa: 0.286; 95% CI: 0.111 to 0.683), respectively.

Conclusions: In vitro colistin testing remains a significant challenge globally. Although the present study results are inconclusive due to the small sample size, we should conduct multi-centric studies globally, taking a considerable sample size representing different Gram-negative bacilli to generate conclusive evidence on the utility of CBDE as a reliable method of colistin susceptibility testing.

Genotypic characterization of carbapenem resistant Enterobacterales in clinical isolates from western Maharashtra

PURPOSE

To study distribution of carbapenemase genes namely; New Delhi metallo-beta-lactamase (blaNDM), Oxacillinase-48 (blaOXA48), Verona Integron-Encoded Metallo-beta-lactamase (blaVIM) and Imipenemase (blaIMP) in carbapenem resistant Enterobacterales (CRE), isolated from clinical samples.

METHOD

This cross-sectional study was conducted at a tertiary care hospital of western Maharashtra over six months period. CREs were identified by conventional disc diffusion and modified carbapenem inactivation method (mCIM). A total of 50 consecutive CRE isolates from clinical samples were subjected to home brewed polymerase chain reaction (PCR) for detection of carbapenemases.

RESULTS

Out of the 50 CRE isolates, at least one of the four carbapenemase genes was detected in 49 (98%) isolates. The frequency of distribution of these genes were NDM 90% (n = 45), OXA48 60% (n = 30) and VIM 12% (n = 6). Dual combination of blaNDM and blaOXA48 (50%) was the commonest pattern observed, which was frequently associated with Klebsiella pneumoniae.

CONCLUSIONS

The study indicate high prevalence of NDM warranting strict anti-microbial stewardship practices. Surveillance of CRE and resistance mechanism is essential to monitor the trend and take informed decision for appropriate anti-microbial therapy.

Prevalence and antimicrobial susceptibility of extended-spectrum beta lactamases-producing Escherichia coli and Klebsiella pneumoniae isolated in selected hospitals of Anyigba, Nigeria

BACKGROUND

Escherichia coli and Klebsiella pneumoniae are commonly implicated in urinary tract infections accounting for majority of the antimicrobial resistance encountered in hospitals.

OBJECTIVES

To determine the prevalence and antimicrobial susceptibility of extended-spectrum beta-lactamases (ESBLs) producing E. coli and K. pneumoniae among patients in Anyigba, Nigeria.

METHODS

This hospital-based cross-sectional study was conducted using urine samples from 200 patients of Grimmard Catholic hospital and Maria Goretti hospital. Urine samples were processed to identify ESBL-producing E. coli and K. pneumoniae using standard microbiological techniques. Isolates were then tested against antimicrobial agents.

RESULTS

A total of 156 bacterial isolates were recovered consisting 128 of E. coli and 28 of K. pneumoniae. Extended spectrum beta-lactamases production was observed in 69% of E. coli and 31% of K. pneumoniae. These pathogens were resistant to 3 or more antibiotics. Of the antimicrobials tested, cefotaxime demonstrated the highest rates of resistance (100%) for both ESBL-producing E. coli and K. pneumoniae. Fifty-four isolates of ESBL-producing E. coli showed a high level of resistance to amoxicillin clavulanic acid (83.3%), ciprofloxacin (83.3%), and ceftazidime (79.6%). ESBL-positive K. pneumoniae isolates were highly resistant to ciprofloxacin (75%), and amoxicillin clavulanic acid (83.3%). Cefoxitin (62.5%) and gentamicin (66.7%) showed substantially higher rates of resistance against these isolates while all 24 strains were resistant to imipenem.

CONCLUSION

This study indicated the prevalence of ESBL-positive Gram-negative pathogens in these study sites and also demonstrated their resistance to a few antibiotics. This highlights the need for new antimicrobials that are potent and improved policy on use of antibiotics.

Validation of an Isothermal Amplification Platform for Microbial Identification and Antimicrobial Resistance Detection in Blood: A Prospective Study

Background: Recent advances in nucleic acid amplification technique (NAAT)-based identification of pathogens in blood stream infections (BSI) have revolutionized molecular diagnostics in comparison to traditional clinical microbiology practice of blood culture. Rapid pathogen detection with point-of-care diagnostic-applicable platform is prerequisite for efficient patient management. The aim of the study is to evaluate an in-house developed, lyophilized OmiX-AMP pathogen test for the detection of top six BSI-causing bacteria along with two major antimicrobial resistance (AMR) markers of carbapenem and compare it to the traditional blood culture-based detection.

Materials and methods: One hundred forty-three patients admitted to the Medical Intensive Care Unit, Narayana Hrudayalaya, Bangalore, with either suspected or proven sepsis, of either gender, of age ≥18 years were enrolled for the study. Pathogen DNA extracted from blood culture sample using OmiX pReP method was amplified at isothermal conditions and analyzed in real time using OmiX Analysis software.

Results: Among the processed 143 samples, 54 were true negative, 83 were true positive, 3 were false negative, and 2 were false positive as analyzed by OmiX READ software. Gram-negative bacteria (91.3%) and gram-positive bacteria (75%) were detected with 100% specificity and 95.6% sensitivity along with the AMR marker pattern with a turnaround time of 4 hours from sample collection to results.

Conclusion: OmiX-AMP pathogen test detected pathogens with 96.5% concordance in comparison to traditional blood culture. Henceforth, OmiX-AMP pathogen test could be used as a readily deployable diagnostic kit even in low-resource settings.

How to cite this article: Maheshwarappa HM, Guru P, Mundre RS, Lawrence N, Majumder S, Sigamani A, et al. Validation of an Isothermal Amplification Platform for Microbial Identification and Antimicrobial Resistance Detection in Blood: A Prospective Study. Indian J Crit Care Med 2021;25(3):299–304.

Multicentre study of the main carbapenem resistance mechanisms in important members of the Enterobacteriaceae family in Iran

Resistance to carbapenems has been increasingly reported from the Enterobacteriaceae family, with different mechanisms in different geographic parts of the world. This study investigated the mechanisms of carbapenem resistance in Escherichia coli, Klebsiella pneumoniae and Enterobacter spp. carried out as a multicentre study (n = 10). All third-generation cephalosporin-resistant E. coli, K. pneumoniae and Enterobacter spp. that had been recovered from the selected provinces were included. Modified Hodge test and Carba NP test were done as a phenotypical method for detection of carbapenemase; the most common carbapenemase was detected by PCR. We evaluated the presence of an active efflux pump by using cyanide 3-chlorophenylhydrazone. Overexpression of AcrA/B and presence of OqxAB was detected by real-time PCR and conventional PCR respectively. Microorganisms in this study included 58 E. coli, 95 K. pneumoniae and 60 Enterobacter spp. Modified Hodge test showed a sensitivity of 41% and a specificity of 83%, and the Carba NP test showed a sensitivity of 26% and a specificity of 92% for detection of carbapenemase. OXA-48 was the most frequently detected carbapenemase, followed by NDM-1. Thirty-nine percent and 27% of positive cyanide 3-chlorophenylhydrazone test organisms included active AcrA/B and OqxAB efflux pumps respectively. The result showed the Carba NP test was more specific than MHT. Data confirmed the involvement of AcrA/B and OqxAB efflux pump as a carbapenem resistance mechanism in selected bacteria. Similar to other reports from the Middle East, we found OXA-48 and NDM-1 to be the most frequent carbapenemase.

High frequency of simultaneous presence of ESBL and carbapenemase producers among nosocomial coliform isolates in Faisalabad, Pakistan

Objectives:

The objective of the current study was to find prevalence of relevant ESBL and carbapenemase producing genes in nosocomial E. coli and K. pneumoniae isolates and to check phenotypic susceptibility of all ESBL positive isolates to carbapenems.

Methods:

Forty ESBL producing clinical isolates of Escherichia coli (n=33) and Klebsiella pneumoniae (n=7) were examined for the presence of β-lactamase genes (CTX-M, CTX-M-1, 2, 3, 4 and TEM). Carbapenem resistance was checked phenotypically and by presence of blaNDM-1 gene.

Results:

Nine (27%) were positive for CTX-M genes, and 10 (30%) for TEM among E. coli isolates. Importantly, six isolates showed co-existence of CTX-M and TEM genes. In K. pneumoniae, two (28%) isolates were positive for CTX-M and one (14%) for TEM genes. Eight (24%) E. coli and one (14%) K. pneumoniae isolates were positive for CTX-M-1. Respective figures for CTX-M-4 were three (10%) and one (14%). CTX-M-2 and CTX-M-3 groups were not represented. Twenty (50%) isolates were resistant to both imipenem and meropenem out of which only four isolates expressed blaNDM-1 gene.

Conclusions:

The significant presence of both ESBL and carbapenemase producers and co-existence of ESBL and carbapenemases in the same isolates is worrisome.

High Prevalence of Multiple Antibiotic-Resistant, Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli in Fresh Seafood Sold in Retail Markets of Mumbai, India

In this study, fresh seafood in retail markets was investigated for the antibiotic susceptibility patterns of the faecal indicator Escherichia coli and distribution of important β-lactamase encoding genes. E. coli were isolated from 50 (37 fish and 13 shellfish) fresh seafood samples and studied with respect to the phenotypic and genotypic characters of antibiotic resistance. Of 475 E. coli isolates from fresh seafood, 71.58% exhibited extended-spectrum β-lactamase (ESBL)-positive phenotypes. A high percentage of isolates were resistant to indicator cephalosporins cefotaxime (95%), cefpodoxime (90.88%) and ceftazidime (90.29%). Relatively higher susceptibilities were recorded against imipenem (74.41%), cefoxitin (66.76%) and meropenem (51.18%). The multiple antibiotic resistance (MAR) index of 97.35% of the isolates was above 0.18. The ESBL genes bla_CTX-M, bla_SHV and bla_TEM were detected in 62.37%, 23.35% and 2.6% of E. coli isolates, respectively. The ESBL-producing isolates also harboured the metallo-β-lactamase-encoding genes bla_OXA (7.06%), bla_NDM (4.42%) and bla_VIM (0.88%). This study highlights the risk of dissemination of multidrug resistant E. coli in seafood consumer communities and also the need to improve the hygiene of the coastal waters, landing centres and the retail markets.

First Indian report on genome-wide comparison of multidrug-resistant Escherichia coli from blood stream infections

Background

Multidrug-resistant (MDR) E. coli with extended-spectrum β-lactamases (ESBLs) is becoming endemic in health care settings around the world. Baseline data on virulence and antimicrobial resistance (AMR) of specific lineages of E. coli circulating in developing countries like India is currently lacking.

Methods

Whole-genome sequencing was performed for 60 MDR E. coli isolates. The analysis was performed at single nucleotide polymorphism (SNP) level resolution to identify the presence of their virulence and AMR genes.

Results

Genome comparison revealed the presence of ST-131 global MDR and ST410 as emerging-MDR clades of E. coli in India. AMR gene profile for cephalosporin and carbapenem resistance differed between the clades. Genotypes bla_CTX-M-15 and bla_NDM-5 were common among cephalosporinases and carbapenemases, respectively. For aminoglycoside resistance, rmtB was positive for 31.7% of the isolates, of which 95% were co-harboring carbapenemases. In addition, the FimH types and virulence gene profile positively correlated with the SNP based phylogeny, and also revealed the evolution of MDR clones among the study population with temporal accumulation of SNPs. The predominant clone was ST167 (bla_NDM lineage) followed by ST405 (global clone ST131 equivalent) and ST410 (fast spreading high risk clone).

Conclusions

This is the first report on the whole genome analysis of MDR E. coli lineages circulating in India. Data from this study will provide public health agencies with baseline information on AMR and virulent genes in pathogenic E. coli in the region.

New Delhi Metallo-β-lactamase and other mechanisms of carbapenemases among Enterobacteriaceae in rural South India

OBJECTIVES

The emergence and dissemination of carbapenem-resistant Enterobacteriaceae (CRE) is an important public health problem. This study aimed to understand the prevalence and mechanisms of carbapenem resistance in clinically important members of Enterobacteriaceae in rural South India.

METHODS

Routine clinical isolates of Escherichia coli and Klebsiella spp. were tested for Ertapenem (ETP) non-susceptibility by the disk diffusion method over a 3-year period (2012-2014). The ETP non-susceptible isolates were preserved, and tested for the MIC of carbapenems and the carriage of major carbapenemase-encoding genes. Representative genes were sequenced and selective isolates were tested for the production of carbapenemase by carbapenem inactivation method.

RESULTS

A total of 444 ETP non-susceptible isolates were identified in increasing incidence over the study period. Among them, MIC₅₀ and MIC₉₀ of carbapenems (excluding ETP) were 0.25-0.5μg/mL and 8-16μg/mL, respectively, and the prevalence of non-ETP carbapenem resistance was estimated as 3%. Among the 177 tested isolates, 65 (37%) had one or more carbapenemase-encoding genes with a predominance of New Delhi Metallo-β-lactamase (NDM; 32 of 65; 49.2%).

CONCLUSIONS

This study documented the MIC range for carbapenems, prevalence and mechanisms of carbapenem resistance among Enterobacteriaceae in rural South India. It substantiated NDM as a leading mechanism of carbapenem resistance and highlighted the importance of MIC testing in patient management.

Molecular Characterization of Extended Spectrum β-lactamase and Carbapenemase Producing Klebsiella pneumoniae from a Tertiary Care Hospital

Objective

The extended-spectrum beta-lactamase (ESBL) and carbapenemase producing gram-negative bacteria among the members of Enterobacteriaceae are of major health concern globally. The present study was carried out to determine proportion and genetic characterization of ESBL and carbapenemase producing Klebsiella pneumoniae strains isolated from intensive care units of a tertiary care hospital.

Materials and methods

A total of 250 non-duplicate K. pneumoniae isolates were recovered from various clinical specimens from our intensive care units from May 2014 to May 2015. Antibiotic susceptibility testing was performed as recommended by Clinical and Laboratory Standard Institute. Phenotypic identification of ESBL and carbapenemase producing isolates were confirmed by the double-disk synergy test, modified Hodge test, imipenem and imipenem-EDTA combined test, respectively. Molecular characterization of β-lactamase genes were performed by polymerase chain reaction.

Results

Out of 250 Klebsiella pneumonaie, 84% isolates were ESBL producers, 66% were carbapenem resistant based on their reduced susceptibility to imipenem, meropenem and ertapenem. Among these 165 carbapenem resistant isolates, 9.7% were positive for bla_NDM-1 and these isolates were also found to be positive for one or more bla genes. Co-carriage of AmpC in ESBL and carbapenem resistant isolates were 7.8% and 3.6%, respectively and were negative for bla_KPC genes.

Conclusion

The study indicated the prevalence of ESBLs and bla_NDM-1, with additional bla genes and AmpC among the K. pneumoniae isolates in our intensive care units. NDM-1 producing Enterobacteriaceae is a growing health care problem. Detection of the prevalence of antibacterial resistance pattern helps towards improved antibiotic policy and empirical antibiotic treatment.

How to cite this article

Beena HB, Shenoy SM, et al. Molecular Characterization of Extended Spectrum β-lactamase and Carbapenemase Producing Klebsiella pneumoniae from a Tertiary Care Hospital. Indian J of Crit Care Med 2019;23(2):61-66.

New Delhi metallo-β-lactamase - type carbapenemases producing Escherichia coli isolates from hospitalized patients: A pilot study

Background & objectives:

Resistances to carbapenem group of antimicrobials among Escherichia coli due to production of carbapenemases, especially the New Delhi metallo-β-lactamase (NDM) types, pose serious challenges in the treatment of infections in healthcare settings. This study was undertaken to detect NDM producing E. coli isolates from hospitalized patients with urinary tract infection (UTI).

Methods:

A total of 30 non-repetitive isolates of E. coli from hospitalized patients with clinical suspicion of UTI were subjected to antimicrobial susceptibility testing. Screening for the production of extended-spectrum β-lactamases (ESBL) was carried out by minimum inhibitory concentration (MIC) test strip ESBL followed by phenotypic confirmation by double-disc synergy test. Phenotypic confirmation of carbapenemase production was carried out by MIC test strip metallo-β-lactamases. Molecular identification of the bla_NDM gene was carried out by polymerase chain reaction (PCR) and sequencing of the amplified fragment.

Results:

Seventeen of the 30 isolates were detected as ESBL producers, of which three were found to be carbapenemase producers. NDM genes were detected by PCR followed by gene sequencing in all three isolates positive for ESBL as well as carbapenemase. The amino acid sequence of the three isolates showed complete identity to the reference sequences of NDM-1, NDM-4 and NDM-8, respectively.

Interpretation & conclusions:

Our study showed the circulation of NDM variants among the clinical isolates of E. coli that were producers of ESBL as well as carbapenemase.

KPC-2 producing ST101 Klebsiella pneumoniae from bloodstream infection in India

This study characterizes KPC-2 producing Klebsiella pneumoniae belonging to ST101. Whole genome sequencing using the Ion Torrent PGM platform with 400 bp chemistry was performed. blaKPC-2 was found on an IncFIIK plasmid associated with ISKpn6 and ISKpn7 without Tn4401. This is the first report of KPC-2 K. pneumoniae from bacteremia in India. The isolate also coded for other resistance genes such as aadA1, aadA2, armA, aac(3)-Ild, aac(6')-Ild for aminoglycoside; blaSHV-11, blaTEM-1B, blaOXA-9, for β-lactams and aac(6')-Ild, oqxA, oqxB, qnrB1 for fluoroquinolones. It belonged to the K17 capsular type. India is endemic to New Delhi metallo-β-lactamase and OXA48-like carbapenemases and K. pneumoniae carbapenemase (KPC) is seldom reported. With high rates of carbapenem resistance, emergence of KPC in India will challenge patient management. The isolate was susceptible to colistin. The patient had a fatal outcome.

Carbapenem resistant Klebsiella pneumoniae isolated from bloodstream infection: Indian experience

Increased incidence of multidrug resistant (MDR) Gram negative infection has resulted in high rates of morbidity and mortality. Klebsiella pneumoniae is one of the commonest MDR pathogens causing bacteraemia with limited therapeutic options such as colistin and tigecycline. Present study focused on molecular characterisation of MDR K. pneumoniae from bloodstream infection and their clinical outcome. A total of 115 K. pneumoniae from January 2015 to September 2016 were included in the study which comprised of phenotypically identified ESBL and carbapenem resistant (CR) isolates. Multiplex PCR was performed for detection of resistance genes encoding β-lactam resistance. This includes bla_SHV, bla_TEM, bla_VEB, bla_PER, bla_CTX-M, bla_DHA, bla_CIT, bla_FOX, bla_ACC, bla_ACT, bla_NDM, bla_OXA48-like, bla_VIM and bla_KPC. Co-expression of bla_SHV, bla_TEM and bla_CTX-M was predominant with 64% (74/115) prevalence. CTX-M-1 was the variant produced by all the isolates producing CTX-M. AmpC was uncommon, seen in 5% of the isolates (6/115). Among the carbapenemases co-expression of bla_NDM and bla_OXA48-like was observed in 28% (32/115) and bla_NDM in 19% (22/115) and bla_OXA48-like in 13% (15/115). bla_KPC was absent. Overall mortality was observed to be 57% (64/113) and mortality among CR K. pneumoniae (Kp) was 68% (50/73). The antibiotics that were administered for treatment of CRKp were colistin in 90% (66/73) and tigecycline in 7% (5/73) and in 99% combined with meropenem (72/73). Prevalence of community acquired and nosocomial infections were 5% (4/73) and 95% (69/73) respectively among CRKp. Minocycline and meropenem susceptibilities were comparable and hence minocycline can be a carbapenem sparing agent. The resistance to β-lactam antibiotics is steadily increasing and are plasmid mediated, their containment in healthcare setting is a challenge.

Study on MICs of Tigecycline in Clinical Isolates of Carbapenem Resistant Enterobacteriaceae (CRE) at a Tertiary Care Centre in North India

INTRODUCTION

Members of family Enterobacteriaceae are the most common Gram-negative bacteria isolated from clinical samples. Those Enterobacteriaceae which have acquired resistance to all β-lactams antibiotics including the carbapenems are considered as Carbapenem Resistant Enterobacteriaceae (CRE). These CRE isolates are often resistant to most other classes of antimicrobials as well, making their treatment a great challenge. Tigecycline is one of the last resort antimicrobials against such multidrug resistant bacteria. Decreased tigecycline susceptibility mediated by efflux pump systems is being reported in clinical strains of Enterobacteriaceae. Minimum Inhibitory Concentration (MIC) data would prove useful in managing infections by these multidrug resistant bacteria and optimizing use of tigecycline.

AIM

To evaluate the MIC values of tigecycline against carbapenem resistant Escherichia coli and Klebsiella pneumoniae isolates.

MATERIALS AND METHODS

This prospective study was carried out from January 2015 to December 2015 at the Department of Microbiology, Era's Lucknow Medical College and Hospital (ELMCH), Lucknow, Uttar Pradesh, India. Antimicrobial susceptibility by disk diffusion (Kirby-bauer) was done for 491 E. coli and K. pneumoniae strains isolated from 1606 samples collected from patients admitted in various wards and ICUs. Imipenem, meropenem and ertapenem 10 μg disks were used for testing of sensitivity to carbapenems. In all isolates, Tigecycline 15 μg (Hi-Media) disk was used to screen for tigecycline resistance. In CRE isolates, MICs of tigecycline were determined by E-test (Ezy MIC TM TG strips, Hi Media) and interpreted using European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2016 guidelines.

RESULTS

Out of 491 isolates tested, 186 (37.9%) were found to be CRE showing resistance to at least one of the three carbapenems tested and these included 99 E.coli and 87 K. pneumoniae. Sensitivity pattern of these two bacterial isolates shows a high level of resistance to most classes of antimicrobials. MIC testing for tigecycline was carried out in 144 CRE isolates and tigecycline resistance (MIC >2 μg/ml) was seen in 12 (8.3%) isolates (eight K.pneumoniae and four E. coli). Eight other isolates were found to have MIC of 2 μg/ml and thus the overall prevalence of isolates with decreased susceptibility was 20 (13.9%).

CONCLUSION

A high prevalence of carbapenem resistance coupled with high tigecycline MICs in clinical isolates of E.coli and K. pneumoniae highlights the judicious use of a combination of antimicrobials. Routine in vitro sensitivity testing to evaluate the clinical utility of tigecycline against such resistant Enterobacteriaceae is warranted.

Approach to Carbapenemase Detection in Klebsiella pneumoniae in Routine Diagnostic Laboratories

INTRODUCTION

Resistance to Carbapenems in Klebsiella may be due to Carbapenem hydrolysing enzymes. Accurate detection of carbapenemase must be done for patient treatment and epidemiological purposes.

AIM

To detect carbapenemase production by performing Modified Hodge Test (MHT), Combined Disk Test (CDT) for Metallo-β-Lactamases (MBL) and PCR for bla_KPC gene, to evaluate the performance of MHT using MacConkey Agar (MCA) and to access the value of MHT for carbapenemase detection.

MATERIAL AND METHODS

Using a prospective laboratory study design, 153 Extended Spectrum Beta-Lactamases (ESBL) producing Klebsiella pneumoniae from clinical samples of patients admitted in the Kasturba Medical College were collected from January 2014 to December 2015. Isolates resistant to carbapenems by disk diffusion were subjected to MHT on MCA and Mueller Hinton agar (MHA). All isolates were tested for (MBL) production by Imipenem and Imipenem-EDTA CDT and subjected to PCR for the presence of bla_KPC gene.

RESULTS

Out of 153 isolates, 54 were resistant to one of the carbapenems. Among these, 13 were positive for MHT on MHA, while 23 were positive by MHT on MCA. Number of MBL producers was 23 (42.5%), while bla_KPC was detected in 2 out of the 54 isolates.

CONCLUSION

Though detection of drug resistance gene remains the method of choice, it can be performed only in centers with adequate resources. Hence, for most laboratories in resource poor countries, the MHT performed on MCA with concomitant CDT for MBL detection seem to be a better option for detection of Carbapenem resistance.

Act Fast as Time Is Less: High Faecal Carriage of Carbapenem-Resistant Enterobacteriaceae in Critical Care Patients

INTRODUCTION

Carbapenem-resistant Enterobacteriaceae (CRE) are drug-resistant Gram-negative bacteria that are present in the community as well as in hospitals. Their infection and colonisation puts critically ill patients at high risk due to the drug-resistant nature of the strains and possible spreading of these organisms, even in a hospital environment.

AIM

To examine the presence and types of Enterobacteriaceae species in patients admitted directly from the community.

MATERIALS AND METHODS

The present study was a one-month pilot conducted in the ICU of a tertiary care hospital in Mumbai, India in 2015. Faecal samples of patients admitted from the community directly to the ICU were analysed using tests like MHT (Modified Hodge) and EDTA for the presence of IMP (action on Imipenem) and KPC (Klebsiella Test Pneumoniae Carbapenemase) producing strains of Enterobacteriaceae. Polymerase Chain Reaction (PCR) was performed to look for VIM, IMP, NDM1, OXA, and KPC genes. Antibiotic Sensitivity Test was carried out as per CLSI guidelines.

RESULTS

The results showed an alarming level of faecal carriage rates in adult ICU patients. Klebsiella pneumonia was the most common carbapenem-resistant isolate, closely followed by Escherichia coli. PCR results revealed nine strains were positive for bla(KPC) gene, from which 7 were Klebsiella pneumoniae and one each of Escherichia coli and Klebsiella oxytoca was observed. Antibiotic Sensitivity Test results showed that the isolates had maximum sensitivity to Colistin (100%) and Tigecycline (95%).

CONCLUSION

These levels indicate that in the absence of CRE screenings, proper isolation of carrier patients is not possible, leading to possible spreading of these resistant bacteria strains in ICUs. A longer period of study is required to obtain more substantial data to validate the results of this pilot.

Occurrence of blaNDM-₁ & absence of blaKPC genes encoding carbapenem resistance in uropathogens from a tertiary care centre from north India

Background & objectives:

Carbapenem resistance mediated by carbapenemases is increasingly being reported worldwide. This study was conducted to know the occurrence of important carbapenem resistance encoding genes in Gram-negative bacilli (GNB) causing complicated urinary tract infection (CUTI), and to look at the genetic diversity of these isolates.

Methods:

The study was carried out on 166 consecutive carbapenem resistant uropathogens (CRU) isolated from cases with CUTI during 2008 and 2012. Carbapenemase production was characterized phenotypically and polymerase chain reaction was used to detect bla_VIM, bla_IMP, bla_KPC, and bla_NDM-1. BOX- PCR was done on 80 randomly selected isolates for molecular typing.

Results:

The bla_VIM gene was present in 34 (43.6%), bla_IMP in five (6.4%) and none of the isolates from 2008 had bla_NDM-1 or bla_KPC genes. Among the isolates from 2012, bla_NDM-1 gene was present in 47 (53.4%), bla_VIM in 19 (24.4%), bla_IMP in one (1.1%) and none had bla_KPC. There were nine isolates during the two years which had multiple genes encoding carbapenemases; while 66 did not have any of the genes tested. Of the 80 isolates subjected to BOX-PCR, 58 could be used for analysis and showed, presence of multiple clusters of carbapenem resistant isolates and absence of a single dominant clone.

Interpretation & conclusions:

The bla_NDM-1 gene was absent in our isolates obtained during 2008 but was present amongst Enterobacteriaceae isolated in 2012. The bla_KPC gene was also not found. Nine isolates obtained during the two years had multiple genes encoding carbapenemases confirming the previous reports of emergence of GNB containing genes encoding multiple carbapenemases. Typing using BOX-PCR indicated that this emergence was not because of clonal expansion of a single strain, and multiple strains were circulating at a single point of time.

Rapid detection of porins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry

The rapid and cost-efficient determination of carbapenem resistance is an important prerequisite for the choice of an adequate antibiotic therapy. A MALDI-TOF MS-based assay was set up to detect porins in the current study. A loss of the components of porin alone such as OmpK35/OmpK36 or together with the production of carbapenemases will augment the carbapenem resistance. Ten strains of Escherichia coli and eight strains of Klebsiella pneumoniae were conducted for both sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and MALDI-TOF MS analysis. MALDI-TOF/TOF MS analysis was then performed to verify the correspondence of proteins between SDS-PAGE and MALDI-TOF MS. The results indicated that the mass spectrum of ca. 35,000, 37,000, and 38,000-m/z peaks of E. coli ATCC 25922 corresponded to OmpA, OmpC, and OmpF with molecular weight of approximately ca. 38, 40, and 41 kDa in SDS-PAGE gel, respectively. The band of OmpC and OmpF porins were unable to be distinguished by SDS-PAGE, whereas it was easy to be differentiated by MALDI-TOF MS. As for K. pneumoniae isolates, the mass spectrum of ca. 36,000 and 38,600-m/z peaks was observed corresponding to OmpA and OmpK36 with molecular weight of approximately ca. 40 and 42 kDa in SDS-PAGE gel, respectively. Porin OmpK35 was not observed in the current SDS-PAGE, while a 37,000-m/z peak was found in K. pneumoniae ATCC 13883 and carbapenem-susceptible strains by MALDI-TOF MS which was presumed to be the characteristic peak of the OmpK35 porin. Compared with SDS-PAGE, MALDI-TOF MS is able to rapidly identify the porin-deficient strains within half an hour with better sensitivity, less cost, and is easier to operate and has less interference.

Resistance and virulence factors of Escherichia coli isolated from chicken

Chicken meat has become an important part of the human diet and besides contamination by pathogenic Escherichia coli there is a risk of antibiotic resistance spreading via the food chain. The purpose of this study was to examine the prevalence of resistance against eight antibiotics and the presence of 14 virulence factors among 75 Escherichia coli strains isolated from chicken meat in the Czech Republic after classification into phylogenetic groups by the multiplex PCR method. More than half of strains belonged to A phylogroup, next frequently represented was B1 phylogroup, which suggests the commensal strains. The other strains were classified into phylogroups B2 and D, which had more virulence factors. Almost half of all E. coli strains were resistant to at least one of eight-tested antibiotics. A multidrug resistance was observed in 13% of strains. The most prevalent virulence genes were iucD, iss and tsh. None of genes encoding toxins was detected. Most of E. coli strains isolated from chicken meat can be considered as nonpathogenic on the basis of analysis of virulence factors, antibiotic resistance and phylogroups assignment. It can provide a useful tool for prediction of a potential risk from food contaminated by E. coli.

Identification and differentiation of carbapenemases in Klebsiella pneumoniae: a phenotypic test evaluation study from jaipur, India

BACKGROUND

Carbapenem resistance is one of the major threats faced in antimicrobial treatment of infections caused by gram negative organisms. In recent years, carbapenem resistance has emerged in Klebsiella pneumoniae isolates due to acquisition of carbapenemases which belong to Ambler class A KPC type enzymes or to Ambler class B metallo-β-lactamases (MBL). Routine lab detection of carbapenemase producing K. pneumoniae isolates is crucial, both for a therapeutic management and an efficient infection control.

MATERIALS AND METHODS

A study was conducted on 60 carbapenem resistant Klebsiella pneumoniae strains which were isolated from various clinical samples over a period of one year (September 2010-August 2011), at a tertiary care hospital in Jaipur. Phenotypic confirmatory test was done by using discs of Meropenem alone and those with phenyl boronic acid (PBA) or Ethylenediaminetetraacetic acid (EDTA) or both, for detection of carbapenemase production and differentiation of KPC and MBL enzymes.

RESULTS

Of the 60 carbapenem resistant Klebsiella pneumoniae isolates, 53 (88.33%) were found to be MBL producers, 4(6.66%) were found to be MBL and KPC co-producers and the rest of the 3(5%) isolates were negative for both MBL and KPC production, as was seen by combined disc testing.

CONCLUSION

The combined disc test is a simple test which can be used for differentiation of carbapenemases and it can be easily incorporated in routine microbiology lab testing.

blaKPC gene Detection in Clinical Isolates of Carbapenem Resistant Enterobacteriaceae in a Tertiary Care Hospital

INTRODUCTION

Carbapenem resistance among Enterobacteriaceae, especially in Klebsiella pneumoniae and Escherichia coli, is an emerging problem worldwide. A common mechanism of carbapenem resistance is the production of class-A, Klebsiella pneumoniae carbapenemase (KPC).

AIMS AND OBJECTIVES

The present study focused on determining the antibiotic resistance pattern and prevalence of bla KPC gene coding for KPC in carbapenem resistant Enterobacteriaceae.

METHODOLOGY

Forty six carbapenem resistant isolates belonging to the family Enterobacteriaceae were tested for antibiotic sensitivity pattern. Modified Hodge Test (MHT) and PCR for bla KPC gene detection were performed on these isolates. Of these, 22 were Klebsiella pneumoniae, 21 were Escherichia coli, 2 were Citrobacter species and 1 was Proteus mirabilis Results: Forty three (93.4%) out of the 46 isolates were resistant to Meropenem, 34 (73.9%) were resistant to Imipenem and 30 (65.2%) were resistant to both Imipenem and Meropenem. Modified Hodge Test was positive in 38 (82.6%) out of 46 isolates and blaKPC gene was detected in 31 (67.4%) isolates. bla KPC gene was detected in 28 out of the 38 MHT positive isolates.

Emergence of NDM - 1 in the Clinical Isolates of Pseudomonas aeruginosa in India

OBJECTIVE

The present study was undertaken to detect the prevalence of the blaNDM-1 metallo beta lactamases (MBLs) in the isolates of Pseudomonas aeruginosa, which were recovered from various clinical samples from hospitalized patients in a tertiary care centre in Pune, India.

METHODS

A total of 200 isolates of P. aeruginosa which were obtained from various clinical samples were subjected to antibiotic susceptibility testing by the disc-diffusion method and their MICs were determined by the Vitek - 2 Automated Antimicrobial Identification and Susceptibility Testing System against imipenem, meropenem, ticarcillin, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin, moxifloxacin, tigecycline, trimethoprim/sulfamethoxazole, ampicillin/sulbactam, piperacillin/tazobactam, cefoperazone/sulbactam, cefepime, tetracycline, ceftazidime, ceftriaxone and colistin. Their MICs were also determined by the Etest method against imipenem, meropenem, piperacillin, tobramycin, ceftazidime, tigecycline and colistin. The presence of blaNDM-1 was detected by PCR and it was confirmed by sequencing the gene which was present in the isolates which exhibited carbapenem resistance. The experimental transferability of the plasmids which carried blaNDM-1 was determined by using E. coli J53 as the recipient.

RESULT

In the present study, four isolates of P. aeruginosa, which carried the blaNDM-1 gene, were resistant to imipenem and meropenem. These blaNDM-1 carrying isolates remained susceptible to colistin. The plasmid carrying blaNDM-1 was successfully transferred from the four isolates to E. coli J53 recipients.

CONCLUSIONS

We are reporting the emergence of the P. aeruginosa carrying NDM-1gene, which exhibited resistance to imipenem and meropenem, for the first time from India.

A pilot study on water pollution and characterization of multidrug-resistant superbugs from Byramangala tank, Ramanagara district, Karnataka, India

Urbanization and industrialization has increased the strength and qualities of municipal sewage in Bangalore, India. The disposal of sewage into natural water bodies became a serious issue. Byramangala reservoir is one such habitat enormously polluted in South India. The water samples were collected from four hotspots of Byramangala tank in 3 months. The biochemical oxygen demand (BOD) and bacterial counts were determined. The fecal coliforms were identified by morphological, physiological, and biochemical studies. The antibiotics sensitivity profiling of isolated bacteria were further carried out. We have noticed that a high content of BOD in the tank in all the 3 months. The total and fecal counts were found to be varied from 1.6 × 10(6) to 8.2 × 10(6) colony forming unit/ml and >5,500/100 ml, respectively. The variations in BOD and total count were found to be statistically significant at p > 0.05. Many pathogenic bacteria were characterized and most of them were found to be multidrug resistant. Salmonella showed resistance to cefoperazone, cefotaxime, cefixime, moxifloxacin, piperacillin/tazobactam, co-trimoxazole, levofloxacin, trimethoprim, and ceftazidime. Escherichia coli showed resistance to chloramphenicol, trimethoprim, co-trimoxazole, rifampicin, and nitrofurantoin while Enterobacter showed resistant to ampicillin, cefepime, ceftazidime, cefoperazone, and cefotaxime. Klebsiella and Shigella exhibited multiple drug resistance to conventional antibiotics. Staphylococcus showed resistance to vancomycin, methicillin, oxacillin, and tetracycline. Furthermore, Salmonella and Klebsiella are on the verge of acquiring resistance to even the strongest carbapenems-imipenem and entrapenem. Present study revealed that Byramanagala tank has become a cesspool of multidrug-resistant "superbugs" and will be major health concern in South Bangalore, India.

Isolation and characterisation of lytic bacteriophages of Klebsiella pneumoniae and Klebsiella oxytoca

Klebsiella bacteria have emerged as an increasingly important cause of community-acquired nosocomial infections. Extensive use of broad-spectrum antibiotics in hospitalised patients has led to both increased carriage of Klebsiella and the development of multidrug-resistant strains that frequently produce extended-spectrum β-lactamases and/or other defences against antibiotics. Many of these strains are highly virulent and exhibit a strong propensity to spread. In this study, six lytic Klebsiella bacteriophages were isolated from sewage-contaminated river water in Georgia and characterised as phage therapy candidates. Two of the phages were investigated in greater detail. Biological properties, including phage morphology, nucleic acid composition, host range, growth phenotype, and thermal and pH stability were studied for all six phages. Limited sample sequencing was performed to define the phylogeny of the K. pneumoniae- and K. oxytoca-specific bacteriophages vB_Klp_5 and vB_Klox_2, respectively. Both of the latter phages had large burst sizes, efficient rates of adsorption and were stable under different adverse conditions. Phages reported in this study are double-stranded DNA bacterial viruses belonging to the families Podoviridae and Siphoviridae. One or more of the six phages was capable of efficiently lysing ~63 % of Klebsiella strains comprising a collection of 123 clinical isolates from Georgia and the United Kingdom. These phages exhibit a number of properties indicative of potential utility in phage therapy cocktails.