Antimicrobial resistance to Citrobacter spp. and Salmonella spp. isolated from goose eggs

Abstract

Infections with bacteria of the genus Salmonella are responsible for a variety of acute and chronic diseases in poultry. Infected poultry flocks are also among the most important reservoirs of salmonellae that can be transmitted through the food chain to humans. Citrobacter belongs to the Enterobacteriaceae family which is closely related to Salmonella. The aim of this study was to examine goose eggs contaminated with Citrobacter spp. and Salmonella spp. and determine the drug resistance pattern of the isolated organisms. Two hundred and forty goose eggs were collected in Zabol region and were transferred to the microbiology laboratory of Zabol University. The egg shells were thoroughly disinfected and the interior contents of individual eggs were pooled into a sterile beaker in groups of four resulting in 60 samples overall. These samples were then incubated at 37°C for 24 h. Swab samples were prepared from the incubated contents and then subcultured on several solid media. Identification of the isolated bacteria was performed using standard bacteriological and biochemical procedures. Final confirmation of Salmonella in the isolates was by slide serum agglutination test. The isolation rates of Salmonella spp. from the egg samples were determined to be at least 3.75%. Disc diffusion tests on Muller–Hinton agar were used to determine the sensitivity to antibacterial agents. Ten antibiotics were studied: ampicillin, colistin, cephalexin, ciprofloxacin, chloramphenicol, gentamycin, furazolidone, nalidixic acid, norfloxacin and tetracycline. Both genera of the bacteria showed 100% susceptibility to ciprofloxacin and norfloxacin. Salmonella isolates showed the most resistance to tetracycline (100%), but Citrobacter isolates showed the most resistance to cephalexin and furazolidone (88.8%).