My Scientific Blog - Research and Articles

Thursday, February 10, 2022

BMC Microbiology, Springer Nature

gyrA ser83 mutation among fluoroquinolone-resistant Salmonella enterica serovars from enteric fever patients in tertiary care hospital, Kathmandu

Prashanna Adhikari, Roshani Maharjan, Subash Paudel, Bikram Malla, Pradeep Kumar Shah, Anup Bastola & Upendra Thapa Shrestha*

* Corresponding author: Upendra Thapa Shrestha, Faculty, Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal. Email: upendrats@gmail.com

BMC Microbiology volume 22, Article number: 51 (2022)

https://doi.org/10.1186/s12866-022-02456-7

ABSTRACT

Background

The management of enteric fever through antibiotics is difficult these days due to the emerging resistance of Salmonella to various antimicrobial agents. The development of antimicrobial resistance is associated with multiple factors including mutations in the specific genes. To know the current status of mutation-mediated fluoroquinolone-resistance among Salmonella enterica serovars; Typhi, Paratyphi A, B and C, this study was focused on detecting gyrA ser83 mutation by restriction digestion analysis of gyrA gene using HinfI endonuclease.

Results

A total of 948 blood samples were processed for isolation of Salmonella spp. and 3.4% of them were found to be positive for Salmonella growth. Out of the 32 Salmonella isolates, 2.2% were S. Typhi and 1.2% were S. Paratyphi A. More interestingly, we observed less than 5% of isolates were resistant to first-line drugs including chloramphenicol, cotrimoxazole and ampicillin. More than 80% of isolates were resistant to fluoroquinolones accounting for 84.4% to levofloxacin followed by 87.5% to ofloxacin and 100% to ciprofloxacin by disc diffusion methods. However, the minimum inhibitory concentration method using agar dilution showed only 50% of isolates were resistant to ciprofloxacin. A total of 3.1% of isolates were multidrug-resistant. Similarly, 90.6% of the Salmonella isolates showed gyrA ser83 mutation with resistance to nalidixic acid.

Conclusions

The increased resistance to fluoroquinolones and nalidixic acid in Salmonella isolates in our study suggests the use of alternative drugs as empirical treatment. Rather, the treatment should focus on prescribing first-line antibiotics since we observed less than 5% of Salmonella isolates were resistant to these drugs.

Keywords: Enteric fever, Salmonella enterica, Fluoroquinolone-resistant, gyrA, ser83 mutation

Citation: Adhikari et al., gyrA ser83 mutation among fluoroquinolone-resistant Salmonella enterica serovars from enteric fever patients in tertiary care hospital, Kathmandu. BMC Microbiology, 2022, 22: 51. https://doi.org/10.1186/s12866-022-02456-7.

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Thursday, January 13, 2022

Faculty Research Grants-UGC, Nepal

A Faculty Research Grants

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.