Identification and Antibiotic Resistance Profile of Salmonella spp. and Citrobacter spp. Isolated from Street-Vended Beverages

Abstract

The risk of foodborne diseases as well as the dissemination of antibiotic resistant bacteria increases with the consumption of street-vended food and beverages. This study investigated the prevalence of Salmonella spp. and Citrobacter spp. in street-vended beverages sold in Chow Kit, Kuala Lumpur, Malaysia. The Kirby-Bauer disk diffusion method was used to identify the antibiotic resistance profile of Salmonella spp. and Citrobacter spp. isolates towards 11 selected antibiotics. Six beverage samples were found positive for presumptive Salmonella spp. and Citrobacter spp. Upon confirmation via Microgen kit and PCR biochemical testing methods, only one isolate was confirmed to be Salmonella enterica serovar Derby while the other isolates were identified as Citrobacter spp. (n= 12; 2 isolates from each positive beverage sample). The antibiogram test showed that 58.3%, 16.7%, and 8.3% of the strains tested were resistance to tetracycline, cephalexin, and ampicillin respectively, while all isolates were fully resistant toward penicillin and erythromycin. The isolate with the highest MAR index (0.45) was S231, with resistance to five of the tested antibiotics (penicillin, erythromycin, tetracycline, cephalexin, and ampicillin). Seven isolates had a MAR index of 0.27 and were resistant to three antibiotics, while the remaining four isolates had the lowest MAR index (0.18) and were resistant to only two antibiotics. This study shows that street-vended beverages have a high risk of spreading antibiotic-resistant bacteria to the public and that Citrobacter spp. should be considered as emerging multidrug-resistant bacteria in the food production system.