Prevalence of Multidrug-Resistant Pseudomonas aeruginosa Isolated from Dairy Cattle, Milk, Environment, and Workers' Hands

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen causing severe infection in animals and humans. This study aimed to determine the ecological distribution and prevalence of multidrug-resistant (MDR) P. aeruginosa isolated from dairy cattle, the environment, and workers' hand swabs. Samples (n = 440) were collected from farms and households (n = 3, each). Rectal swabs, udder skin swabs, milk, workers' hand swabs, feed, water, water sources, and beddings were collected. Samples were subjected to the bacterial identification of P. aeruginosa via 16S rRNA. Antimicrobial resistance (AMR) was detected either phenotypically using an antibiotic susceptibility test or genotypically with AMR resistance genes (ARGs) such as drfA, sul1, and ermB. P. aeruginosa was detected on dairy farms and households (10.3-57.5%, respectively), with an average of 23.2%. The resistance of dairy farm strains was observed against sulfamethoxazole, imipenem, cefepime, piperacillin-tazobactam, and gentamycin (100%, 72.7%, 72.7%, 68.8%, and 63.3%, respectively). Meanwhile, the resistance of household strains was observed against sulfamethoxazole, imipenem, amoxicillin, gentamicin, cefepime, and erythromycin by 91.3%, 82.6%, 75.4%, 75.4%, 68.1%, and 63.8%, respectively. The susceptibility of farm strains was detected against norfloxacin, ciprofloxacin, and levofloxacin (90.9%, 84.8%, and 72.7%, respectively). Meanwhile, the susceptibility of household strains was detected against ciprofloxacin, amikacin, and norfloxacin (100%, 84.1%, and 72.5%, respectively). About 81.4% of P. aeruginosa strains were MDR. ARGs (drfA, sul1, and ermB) were detected in farm strains (48.5%, 72.7%, and 24.4%, respectively) and household strains (50.7%, 72.5%, and 47.8%, respectively). Almost all P. aeruginosa had MAR over 0.2, indicating repeated application of antibiotics. P. aeruginosa prevalence was fivefold higher in households than on farms. MDR strains were higher amongst household strains than farm strains.

Keywords: P. aeruginosa; antimicrobial resistance; dairy cattle.