ABSTRACT
Antimicrobial resistance in Enterobacteriaceae is an emerging global public health problem. Numerous studies have reported community-acquired AmpC beta-lactamase and extended spectrum beta-lactamase (ESBL) producing Enterobacteriaceae in Nepal. However, there are limited data on community-acquired Metallo-beta-lactamase (MBL) producing Enterobacteriaceae. A hospital-based descriptive cross-sectional study was conducted using 294 Enterobacteriaceae isolates from a total of 2,345 different clinical specimens collected from patients attending a tertiary care hospital in Nepal. Bacteria were isolated using standard microbiological growth media and identified using biochemical tests. For antimicrobial susceptibility testing, Kirby-Bauer disc diffusion technique was used. AmpC, ESBL, and MBL productions were detected by using combined disc method. AmpC, ESBL, and MBL productions were detected in 19.4%, 29.6%, and 8.5% of total Enterobacteriaceae isolates respectively. Higher rates of beta-lactamases production were seen among the isolates from in-patients in comparison with those from out-patients. However, 11.6%, 25%, and 3.7% of the total isolates from out-patients were AmpC, ESBL, and MBL producers respectively. The co-production of the beta-lactamases was also detected, with two Klebsiella pneumoniae isolates producing all three beta-lactamases. One MBL producing Proteus vulgaris isolate that was pan-resistant with no remaining treatment options was also isolated. Prevalence of drug resistant Enterobacteriaceae in our study was very high. Detection of AmpC, ESBL, and MBL positive isolates from out-patients, who did not have recent history of hospital visit, indicated the community dissemination of the drug resistant bacteria. This is a matter of great concern and an immediate attention to formulate strategies to prevent further development and spread of antibiotic resistance is required.
ABSTRACT
BACKGROUND AND OBJECTIVES: Carbapenems have been the choice of antibiotics for the treatment of infections caused by multidrug-resistant bacteria. The main objective of this study was to determine the prevalence of carbapenemase (bla VIM and bla IMP ) producing isolates among Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii. MATERIALS AND METHODS: A total of 1,151 clinical samples were collected from the patients visiting Annapurna Neurological Institute and Allied Science and Annapurna Research Centre, Kathmandu, between June 2017 and January 2018. Antibiotic susceptibility testing (AST) was performed on the Enterobacteriaceae, P. aeruginosa and A. baumannii isolates using the Kirby-Bauer disk diffusion method. The modified Hodge test (MHT) was performed on the carbapenem-resistant isolates to confirm carbapenemase production. DNA was extracted and then screened for bla VIM and bla IMP genes by multiplex PCR. RESULTS: Of the total 1,151 clinical samples, 253 (22.0%) showed positive growth. Of them, 226 (89.3%) were identified as Enterobacteriaceae, P. aeruginosa, and A. baumannii. Among the 226 isolates, 106 (46.9%) were multidrug-resistant. Out of the 106, 97 (91.5%) isolates showed resistance to at least one of the carbapenem used. Among the 97 carbapenem-resistant isolates, 67 (69.1%) showed the modified Hodge test (MHT) positive results. bla VIM and bla IMP were detected in 40 and 38 isolates respectively using multiplex PCR assay. CONCLUSION: This study determined a high prevalence of MDR and carbapenem resistance among Enterobacteriaceae, P. aeruginosa, and A. baumannii as detected by the presence of bla VIM and bla IMP genes. This study recommends the use of rapid and advanced diagnostic tools along with conventional phenotypic detection methods in the clinical settings for early detection and management of drug-resistant pathogens to improve treatment strategies.
ABSTRACT
BACKGROUND: Antibiotic resistance mediated by the production of extended-spectrum ß-lactamases (ESBLs) and AmpC ß-lactamases is posing a serious threat in the management of the infections caused by Gram-negative pathogens. The aim of this study was to determine the prevalence of two AmpC ß-lactamases genes, bla CITM and bla DHAM, in Gram-negative bacterial isolates. MATERIALS AND METHODS: A total of 1151 clinical samples were obtained and processed at the microbiology laboratory of Annapurna Neurological Institute and Allied Science, Kathmandu between June 2017 and January 2018. Gram-negative isolates thus obtained were tested for antimicrobial susceptibility testing (AST) using Kirby-Bauer disk diffusion method. AmpC ß-lactamase production was detected by disk approximation method using phenylboronic acid (PBA). Confirmed AmpC ß-lactamase producers were further screened for bla CITM and bla DHAM genes by conventional polymerase chain reaction (PCR). RESULTS: Out of 1151 clinical specimens, 22% (253/1152) had bacterial growth. Of the total isolates, 89.3% (226/253) were Gram-negatives, with E. coli as the most predominant species (n=72) followed by Pseudomonas aeruginosa (n=41). In the AST, 46.9% (106/226) of the Gram-negative isolates were multidrug resistant (MDR). In disk diffusion test, 113 (50%) isolates showed resistance against cefoxitin, among which 91 isolates (83 by disk test and Boronic acid test, 8 by Boronic test only) were confirmed as AmpC ß-lactamase-producers. In PCR assay, 90.1% (82/91) and 87.9% (80/91) of the isolates tested positive for production of bla CITM and bla DHAM genes, respectively. CONCLUSIONS: High prevalence of AmpC ß-lactamase-producers in our study is an alarming sign. This study recommends the use of modern diagnostic facilities in the clinical settings for early detection and management which can optimize the treatment therapies, curb the growth and spread of the drug-resistant pathogens.
