Mahadevan Kumar

First Report of blaNDM-1 in Raoultella ornithinolytica

The genus Raoultella is composed of Gram-negative, aerobic, oxidase-negative, catalase-positive, nonmotile, capsulated rods belonging to the Enterobacteriaceae family ([1][1]). Raoultella ornithinolytica is found in aquatic and hospital environments ([2][2]). Occurrence of Raoultella in human

Emergence of Escherichia coli, Co-Producing NDM-1 and OXA-48 Carbapenemases, in Urinary Isolates, at a Tertiary Care Centre at Central India.

OBJECTIVE To detect genes encoding carbapenem resistance in urinary isolates of Escherichia coli recovered from hospitalized patients in tertiary care centre in Pune, India. METHODS From Jan 2012 to Dec 2012, a total of 300 consecutive non-duplicate (one isolate per patient) clinical isolates of Escherichia coli were recovered from urine cultures of hospitalized patients including hospital acquired infection cases admitted to the medical and surgical intensive care units. Polymerase chain reaction (PCR) assays and sequencing was used to determine the presence of beta-lactamase encoding genes. Conjugation experiments were performed to determine the transferability of beta-lactamase. RESULTS All the isolates were completely resistant to the second and third generation cephalosporins tested as well as carbapenems. All the isolates showed 100% susceptibility to tigecycline and colistin in vitro. Conjugation experiments demonstrated that blaNDM-1 was transferable via plasmid. All the isolates showed presence of blaNDM-1 and co-association of blaOXA-48 was 25/45(55%) of the isolates. Repetitive element based PCR (REP PCR), Enterobacterial Repetitive Intergenic Consensus (ERIC PCR) and Randomly Amplified Polymorphic DNA (RAPD) revealed a diversity of six clonal types among E.coli isolates. CONCLUSION Co-production of NDM-1with OXA-48 in urinary isolates of E. coli was detected for the first time in India. Transmission of plasmid carrying these resistant genes to other members of Enterobacteriaceae will increase incidence of multidrug resistance. Early detection of these genes will help in prevention and adequate infection control by limiting the spread of these organisms.

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.

Carbapenem Resistance among Enterobacter Species in a Tertiary Care Hospital in Central India.

Objective. To detect genes encoding carbapenem resistance among Enterobacter species in a tertiary care hospital in central India. Methods. Bacterial identification of Enterobacter spp. isolates from various clinical specimens in patients admitted to intensive care units was performed by routine conventional microbial culture and biochemical tests using standard recommended techniques. Antibiotic sensitivity test was performed by standard Kirby Bauer disc diffusion technique. PCR amplification and automated sequencing was carried out. Transfer of resistance genes was determined by conjugation. Results. A total of 70/130 (53.84%) isolates of Enterobacter spp. were found to exhibit reduced susceptibility to imipenem (diameter of zones of inhibition ≤13 mm) by disc diffusion method. Among 70 isolates tested, 48 (68.57%) isolates showed MIC values for imipenem and meropenem ranging from 32 to 64 mg/L as per CLSI breakpoints. All of these 70 isolates were found susceptible to colistin in vitro as per MIC breakpoints (<0.5 mg/L). PCR carried out on these 48 MBL (IP/IPI) E-test positive isolates (12 Enterobacter aerogenes, 31 Enterobacter cloacae, and 05 Enterobacter cloacae complex) was validated by sequencing for beta-lactam resistance genes and result was interpreted accordingly. Conclusion. The study showed MBL production as an important mechanism in carbapenem resistance in Enterobacter spp. and interspecies transfer of these genes through plasmids suggesting early detection by molecular methods.

Multidrug resistant NDM-1 metallo-beta-lactamase producing Klebsiella pneumoniae sepsis outbreak in a neonatal intensive care unit in a tertiary care center at central India

OBJECTIVE The objective of the following study is to detect genes encoding carbapenem resistance in Klebsiella pneumoniae sepsis outbreak in a neonatal intensive care unit (NICU). MATERIALS AND METHODS Antibiotic sensitivity test was performed by standard Kirby Bauer disc diffusion technique and minimum inhibitory concentrations of antibiotics was determined by VITEK-2. Polymerase chain reaction (PCR) assays and sequencing was used to determine the presence of beta-lactamase encoding genes. Conjugation experiments were performed to determine the transferability of beta-lactamase. Isolate relatedness were determined by repetitive-element PCR (REP), enterobacterial repetitive intergenic consensus (ERIC) PCR and random amplified polymorphic deoxyribonucleic acid (RAPD). RESULTS All the isolates were completely resistant to the second and third generation cephalosporins tested as well as carbapenems. Susceptibility profiling of the isolates indicated that 100% retained susceptibility to tigecycline and colistin. Conjugation experiments indicated that blaNDM-1 was transferable and likely through a plasmid-mediated event. All the isolates showed the presence of blaNDM-1 with co association of blaCTX-M-15. REP-PCR, ERIC-PCR and RAPD revealed a single clonal type circulating in NICU environment. CONCLUSION Co-production of NDM-1 with CTX-M-15 in K. pneumoniae isolates was detected for the first time in our NICU. Transmission of plasmid carrying these resistant genes to other members of Enterobacteriaceae will increase the incidence of multidrug resistance. Early detection of these genes will help in prevention and adequate infection control by limiting the spread of these organisms.

First Report of an Enterobacter ludwigii Isolate Coharboring NDM-1 and OXA-48 Carbapenemases

Enterobacter spp. have emerged as pathogens responsible for hospital-acquired infections. Carbapenem resistance is increasingly being reported in this species, which is a matter of concern. Enterobacter spp. can produce abdominal, urinary tract, meningeal, and surgical site infections. In the

Use of immunization as strategy for outbreak control of varicella zoster in an institutional setting

BACKGROUND Outbreaks of varicella gets reported often in India. However, outbreak in health care providers living in closed institutional setting and role of vaccination as post exposure prophylaxis for control of outbreak has not been studied extensively. This paper presents epidemiological investigation and control strategy undertaken in such scenario. METHODS This is an epidemiological investigation of chickenpox in nursing students which highlights role of early identification and appropriate control strategy to prevent explosive outbreak in high risk vulnerable population. Vaccination of all susceptible in addition to isolation of cases, quarantine of suspects and proper screening for new cases was the major control strategy adopted. RESULTS The index case was imported and all eight cases occurred within the incubation period of the case. Two cases occurred in students previously vaccinated for chickenpox. No second or third wave of infection occurred showing vaccination as effective tool in outbreak control strategy. CONCLUSION Early identification of cases and vaccination of all susceptible contributed to effective control of the outbreak.

Presence of a novel variant NDM-10, of the New Delhi metallo-beta-lactamase in a Klebsiella pneumoniae isolate.

This study showed that the prevalence of 3GC resistant Enterobacteraceae and non‐fermenting Gram‐negative Bacilli in patients admitted to ICUs of our hospital was substantial while the prevalence of NDM‐1 was substantially low (3.3%). GI colonisation by 3GC and carbapenem‐resistant pathogens increases the risk of clinical infections by these pathogens and subsequent human to human transmission.[3]

Molecular Characterization of Carbapenem Resistant Isolates of Acinetobacter baumannii in An Intensive Care Unit of A Tertiary Care Centre at Central India

OBJECTIVE To detect genes encoding carbapenem resistance in Acinetobacter baumannii in an intensive care unit. METHODS A. baumannii isolates were recovered from various clinical specimens of hospitalized patients admitted to the Medical and Surgical intensive care units of a tertiary care centre in Pune. Bacterial identification was performed by routine conventional microbial culture and biochemical tests using standard recommended techniques. Antibiotic sensitivity test was performed by standard Kirby Bauer disc diffusion technique. PCR amplification and automated sequencing was carried out. RESULTS A total of 155 /368 (42.11%) isolates A. baumannii were found to have reduced susceptibility to imipenem (diameter of zones of inhibition ≤13mm) by disc diffusion method. Among these 155 isolates tested 130 (83.87%) isolates showed MIC values for imipenem and meropenem ranging from16-64 mg/L as per CLSI breakpoints. Among these 155 isolates, Carbapenemase production was confirmed by Modified Hodge test for 93 (60%) isolates. Out of 155 isolates, DDST was positive for 89 (57.41%), CDST was positive for 73(47.09%) and MBL (IP/IPI) E-test was positive for 105 (67.74%). blaOXA-51 gene was detected in 47/105 (44.76%), blaOXA-23 gene in 55/105 (52.38%) and blaOXA-58 like gene in 15/105 (14.28%). CONCLUSION MBL production along with co- production of OXA enzymes are considered to be the important reason for resistance to imipenem in Acinetobacter in our health care settings. Hence, early detection of these drug resistant genes by molecular methods is essential in limiting the spread of infection due to these organisms.

Phenotypic detection and molecular characterization of beta-lactamase genes among Citrobacter species in a tertiary care hospital.

Objective: To examine the distribution, emergence, and spread of genes encoding beta-lactamase resistance in Citrobacter species isolated from hospitalized patients in a tertiary care hospital. Methods: A prospective study was conducted in a 1000-bed tertiary care center in Pune, India from October 2010 to October 2013. A total of 221 Citrobacter spp. isolates were recovered from clinical specimens from different patients (one isolate per patient) admitted to the surgical ward, medical ward and medical and surgical Intensive Care Units. Polymerase chain reaction (PCR) assays and sequencing were used to determine the presence of beta-lactamase encoding genes. Conjugation experiments were performed to determine their transferability. Isolate relatedness were determined by repetitive element based-PCR, enterobacterial repetitive intergenic consensus-PCR and randomly amplified polymorphic DNA. Results: Among 221 tested isolates of Citrobacter spp. recovered from various clinical specimens, 179 (80.9%) isolates showed minimum inhibitory concentration (MIC) >4 μg/ml against meropenem and imipenem. One hundred and forty-five isolates with increased MICs value against carbapenems were further processed for molecular characterization of beta-lactamase genes. Susceptibility profiling of the isolates indicated that 100% retained susceptibility to colistin. Conjugation experiments indicated that blaNDM-1was transferable via a plasmid. Conclusion: The ease of NDM-1 plasmid transmissibility may help their dissemination among the Citrobacter species as well as to others in Enterobacteriaceae. Early detection, antimicrobial stewardship and adequate infection control measures will help in limiting the spread of these organisms.