PCR-Based Detection of Extended-Spectrum ß-Lactamases (bla CTX-M-1 and bla TEM ) in Escherichia coli, Salmonella spp. and Klebsiella pneumoniae Isolated from Pigs in North Eastern India (Mizoram).

Cephalosporins are major antimicrobials used to treat serious infections. However, their effectiveness is being compromised by the emergence of extended-spectrum ß-lactamases (ESBLs). A total of 138 enteric bacteria were isolated from 53 faecal samples of pigs collected from different districts of Mizoram, of which 102 (73.91 %) were Escherichia coli, 26 (18.84 %) were Salmonella spp. and 10 (7.25 %) were Klebsiella pneumoniae. Phenotypic confirmatory test (Double Discs Synergy Test) showed that 8 (5.80 %) E. coli isolates were ESBLs producer. PCR analysis confirmed that out of the eight isolate, 7 (5.07 %) harboured bla CTX-M-1 gene and/or bla TEM gene. Of the eight positive isolates, 7 (5.07 %) and 3 (2.17 %) were found to be positive for bla CTX-M-1 gene and bla TEM gene, respectively, of which 3 (2.17 %) isolates were positive for both the genes. Only 4 (2.90 %) E. coli isolates carried bla CTX-M-1 gene alone. Agarose gel electrophoresis showed that all the isolates were carrying plasmids ranging between 0.9 and ~30 kb. Out of the seven isolates positive for bla CTX-M-1 and/or bla TEM , 2 (1.84 %) isolates were confirmed for bla CTX-M-1 gene in their plasmid. Only one E. coli isolate was found to be positive for both the genes in its plasmid. The resistance plasmid could not be transferred to a recipient by in vitro horizontal gene transfer method.

Detection and characterization of extended-spectrum ß-lactamases (blaCTX-M-1 and blaSHV ) producing Escherichia coli, Salmonella spp. and Klebsiella pneumoniae isolated from humans in Mizoram.

AIM: The present study was conducted to isolate and characterize the extended spectrum ß-lactamases (ESBLs) producing enteric bacteria in human beings in Mizoram, India. MATERIALS AND METHODS: Fecal samples were collected from human beings with or without the history of diarrhea from different hospitals of Mizoram. Samples were processed for isolation and identification of Escherichia coli, Salmonella and Klebsiella pneumoniae. All the isolates were subjected to antibiotic sensitivity assays. Phenotypically, ESBLs production ability was determined by double discs synergy test (DDST) method. ESBLs producing isolates were subjected to polymerase chain reaction (PCR) for detection of ESBLs genes. Plasmids were cured by acridine orange. Transfer of resistance from a donor to recipient strains was done by in vitro horizontal method. RESULTS: A total of 414 enteric bacteria were isolated from 180 fecal samples (113 were from diarrheic patients and 67 were from non-diarrheic patients), of which 333 (80.44%), 52 (12.56%), and 29 (7.00%) were E. coli, K. pneumoniae and Salmonella spp., respectively. Double discs synergy test (DDST) exhibited 72 (21.62%) E. coli, 12 (23.08%) K. pneumoniae and 4 (13.79%) Salmonella spp. were ESBLs producers. Altogether, 24 (13.04%) isolates were found to be positive for at least one resistance genes under this study. A total of 36 (8.70%) E. coli, 4 (0.97%) K. pneumoniae and 2 (0.48%) Salmonella spp. were found to be positive for blaCTX-M-1 gene by PCR. Similarly, 5 (1.21%) E. coli and 4 (0.97%) K. pneumoniae isolates were found to be positive for blaSHV gene. A total of 3 (0.72%) K. pneumoniae isolates were recorded as positive for both blaCTX-M-1 and blaSHV genes. All the isolates were carrying plasmids ranging between 0.9 kb and ~30 kb. The resistance plasmid could not be transferred to a recipient by in vitro horizontal gene transfer method. CONCLUSION: ESBLs producing enteric bacteria are circulating in human population in North Eastern Region of India. Indiscriminate use of antibiotics should be avoided to control the menace of multidrug resistance bacteria in the environment, animals, and human beings.