Isolation and identification of enteric bacteria from different water sources at Mymensingh city, Bangladesh and their antibiogram study

Abstract

The goal of the current study was to separate and characterize the enteric bacteria found in water samples taken from various Mymensingh municipal sources and places. A total of 40 water samples were examined. Through the use of polymerase chain reaction (PCR), biochemical testing, staining, and culturing enteric bacteria were isolated and identified. The antibiotic resistance phenotype was examined using the disk diffusion assay. Out of 40 isolates that tested positive for bacterial growth, 3 (7.5%) were identified as Salmonella spp., 6 (15%) as Shigella spp., 14 (35%) as E. coli, and 3 (7.5%) as Vibrio spp. Molecular detection of Salmonella spp. were confirmed by PCR-based detection of the bcfC gene, Shigella species by the invC gene, E. coli by the 16S rRNA gene, and Vibrio spp. by the groEL gene. Furthermore, PCR-confirmed isolates were tested for antibiotic resistance to 12 routinely used antibiotics. All Salmonella isolates were 100% resistant to Amoxicillin but 100% sensitive to Azithromycin. However, varied sensitivity was seen against Cefepime (80%), Gentamycin (80%), Levofloxacin (75%), Cotrimoxazole (74%), and Amikacin (70%). The isolates also showed resistance to Ceftazidime (70%), as well as Ceftriaxone (33%). Shigella spp. isolates showed increased resistance to Cefepime (83%) and Ceftazidime (67%). Additionally, resistance to Amoxicillin (17%) and Colistin (10%) was shown to be lower. In addition, Azithromycin, Levofloxacin, Cotrimoxazole, Ceftriaxone, Amikacin, and Gentamicin showed nearly no resistance or significant susceptibility E. coli isolates showed stronger resistance patterns to amoxicillin (100%), and colistin (93%). Cefepime (72%), Cotrimoxazole (72%), and Azithromycin (72%). The lower levels of resistance to ceftriaxone, amikacin, ceftazidime, levofloxacin, and gentamicin were also seen. The higher resistance patterns were shown by the isolated Vibrio spp. against Ampicillin (100%), Cefepime (81%), Cefixime (72%), Amoxicillin (70%), Erythromycin (67%), and Ceftazidime (67%). On the other hand, isolates with high and moderate sensitivity were found to be gentamicin, levofloxacin, doxycycline, cotrimoxazole, and amikacin. The study’s conclusions point to recent and ongoing contamination of the water sources, putting residents who depend on the water for drinking at risk for gastrointestinal illnesses.