Detection of Some Antibiotic-Resistance Genes (qnrB, qnrS, parE, and armA) for Escherichia coli Isolated from Tigris River, Baghdad, Iraq

Abstract

Safe water is a crucial resource for the survival and sustenance of life, and its scarcity is a major cause of water-related ailments, particularly in underdeveloped nations.  The aim of this study was to determine the antibiotic sensitivity pattern of Escherichia coli isolated from the surface waters of the Tigris River and the detection of resistance genes (qnrB, qnrS, parE, and armA) for E. coli. A total of 32 bacterial isolates of E coli were collected for analysis from four distinct sites: S1 Al-Muthana Bridge, S2 Al-Sarrafia Bridge, S3 Al-Senak Bridge, and S4 Al-Jadriyah Bridge. Water samples were collected from November 2023 until July 2024. The isolation of E. coli is performed using membrane filtration techniques and biochemical analysis followed by the VITEK2. The antimicrobial susceptibility of E. coli isolates was assessed using the Kirby-Bauer disk diffusion method, employing a selection of 10 specific antibiotics for evaluation. The resistance genes for E. coli isolates were detected using the PCR technique. The results showed that both nitrofurantoin and ampicillin showed significantly higher resistance (100%), significant proportions of resistance to some β-lactam antibiotics              (ceftazidime, cefoxitin, and ampicillin were 94%,94%,100% respectively) , another significant resistance for aminoglycosides antibiotics ( gentamycin and amikacin, 81-84%), cephalosporins antibiotics group showed significant differences ( ceftriaxone and cefuroxime , 59-93.8%), carbapenems antibiotics ( imipenem,72%), quinolones group presented low resistance proportion ( ciprofloxacin, 43.8%). All identified genes are complete sets with two, three, or four genes. Fourteen isolates showed resistance to fluoroquinolones (ciprofloxacin), and 26 showed resistance to aminoglycosides (gentamycin).  Nine isolates (28.1%) showed the presence of qnrB, and 7 isolates (21.9%) showed the presence of qnrS genes. Of the 26 resistant isolates to gentamycin, 20 isolates (62.5%) showed the presence of the armA gene, and the parE gene was found among all selected isolates for fluoroquinolones and aminoglycosides (100%). The double association qnrB and qnrS was found in 12 isolates (37.5%), This research highlights the necessity of implementing regular surveillance of urban rivers to control the spread of antimicrobial resistance (ARM) genes in aquatic environments.