Phenotypic and Genotypic Characteristics of Antimicrobial Resistance in Citrobacter freundii Isolated from Domestic Ducks (Anas platyrhynchos domesticus) in Bangladesh

Abstract

Antimicrobial resistance (AMR) in <i>Citrobacter freundii</i> poses a serious challenge as this species is one of the sources of nosocomial infection and causes diarrheal infections in humans. Ducks could be the potential source of multidrug-resistant (MDR) <i>C. freundii</i>; however, AMR profiles in <i>C. freundii</i> from non-human sources in Bangladesh have remained elusive. This study aimed to detect <i>C. freundii</i> in domestic ducks (<i>Anas platyrhynchos domesticus</i>) in Bangladesh and to determine their phenotypic and genotypic antibiotic susceptibility patterns. A total of 150 cloacal swabs of diseased domestic ducks were screened using culturing, staining, biochemical, polymerase chain reaction (PCR), and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) to detect <i>C. freundii</i>. Phenotypic and genotypic antibiotic susceptibility patterns were done by the disk diffusion method and PCR, respectively. In total, 16.67% (25/150) of the samples were positive for <i>C. freundii</i>. <i>C. freundii</i> isolates showed a range of 20% to 96% resistance to cefotaxime, gentamicin, levofloxacin, ciprofloxacin, cotrimoxazole, tetracycline, ampicillin, and cephalexin. More than 60% of the isolates were phenotypically MDR, and the index of multiple antibiotic resistance ranged from 0.07 to 0.79. Genes encoding resistance to beta-lactams [<i>bla</i>_TEM-1-88% (22/25), <i>bla</i>_CMY-2-56% (14/25), <i>bla</i>_CMY-9-8% (2/25), and <i>bla</i>_CTX-M-14-20% (5/25)], sulfonamides [<i>sul1</i>-52% (13/25), <i>sul2</i>-24% (6/25)], tetracyclines [<i>tetA</i>-32% (8/25) and <i>tetB</i>-4% (1/25)], aminoglycosides [<i>aacC4</i>-16% (4/25)], and fluoroquinolones [<i>qnrA</i>-4% (1/25), <i>qnrB</i>-12% (3/25), and <i>qnrS</i>-4% (1/25)] were detected in the isolated <i>C. freundii</i>. To the best of our knowledge, this is the first study in Bangladesh to detect MDR <i>C. freundii</i> with their associated resistance genes from duck samples. We suggest addressing the burden of diseases in ducks and humans and associated AMR issues using the One Health approach.