Faculty Research Grants-UGC, Nepal

 

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OCCURRENCE OF β-LACTAM RESISTANT BACTERIAL GENES FROM CLINICAL, ENVIRONMENTAL AND POULTRY ISOLATES

ABSTRACT 

The widespread and irrational use of antibiotics is rampant in many parts of the world including Nepal. In addition, the use of antibiotics in the growth of food animals in veterinary practice and food preparation is of grave concern these days. These all factors contribute to the emergence of drug-resistant strains of bacteria which possess a problem in therapeutic management. Besides, the regular reporting of the increased resistance among the strains of pathogenic microorganisms from different clinical specimens, the higher resistance of antibiotics among the bacterial pathogens from wastewater and poultry have been published by many authors. However, reporting of the resistance genes from those isolates was not documented in our contest. Hence, this study was conducted to find the distribution pattern of resistance genes among the bacterial isolates from different sources including clinical, animal and environmental samples. For this work, bacterial pathogens such as Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa will be isolated separately from clinical specimens, wastewater and poultry samples.  These organisms were then subjected to antimicrobial susceptibility testing using the modified Kirby Bauer disc diffusion method as described in CLSI guidelines. The pathogens were further subjected to screening of resistance genes including bla_TEM, mcr-1, mecA and bla_NDM-1 genes using conventional PCR. Out of 1245 clinical samples including blood, pus and wound, 80 S. aureus were isolated and 47.5 % (38) of them were methicillin-resistant S. aureus. A total 32 (84.2%) MRSA isolates possess mecA gene. Likewise, we observed 89 (15.3%) S. aureus from a study at different hospital among pus specimens.  Of which, 38 were MRSA and 23 of them carry mecA gene. On the other hand, the occurrence of mcr-1 gene among E. coli isolates was found to be 91.6% and 44% from clinical and poultry origins respectively. Most of E. coli isolates from different origins were ESBL producers carrying 41.2% of the blaTEM gene from the clinical origin and 57.5% of blaTEM gene from the water samples. The mecA gene was also found to be higher (46.7%) among MRSA isolates from water samples. Although P. aeruginosa isolated from the clinical specimens in our study showed resistance to most of the antibiotics used, the occurrence of bla_NDM-1 gene was lower (17.8%) as compared to other resistant genes. The resistant genes were found to be ubiquitous among bacterial pathogens from different sources. Moreover, the presence of those genes in transposons or plasmid DNA indicates the potential threat of horizontal gene transfer and the emergence of superbugs. Hence, it is an important issue to address one health concept and alert the policymakers to formulate strict antibiotic prescription policy in the clinical settings, prohibition of the direct disposal of hospital waste or antimicrobial waste to the environment and strict avoidance of antibiotics uses in animal feeds and farmings. We all should be aware that without the good health of animals and the environment, we can't think about our good health.

 

Keywords: Antimicrobial resistance, MRSA, ESBL, MBL, Resistant genes (mecA, mcr-1, bla_TEM, bla_NDM-1)

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