Multi-Antibiotic Resistant Citrobacter freundii in Eggs: A Silent Public Health Threat

Abstract

Background: Improper handling of poultry, particularly in developing countries like Bangladesh, can lead to foodborne illnesses. Citrobacter freundii, a Gram-negative bacteria, is a silent emerging threat causing diseases and spreading antibiotic resistance. This study aimed to identify the multidrug resistant (MDR) C. freundii from poultry egg samples through biochemical and molecular characterization. Materials and Methods: A total of 50 poultry egg samples (both outer and inner) were collected from different farms located in Dhaka, Bangladesh within six months. Isolation of pathogens with selective bacteriological media such as McConkey agar, Xylose Lysine Deoxycholate agar, Salmonella-Shigella agar, and specific biochemical tests were performed to identify the Citrobacter isolates. The antibiotic sensitivity pattern of the isolates were determined by the disk diffusion method. Multidrug-resistant isolates were further identified by 16S rRNA gene sequencing and BLASTn analysis. Results: Out of 50 samples, 60% (30) were found positive for Gram negative Enterobacteriaceae. Among them, 50% of the samples were found to be contaminated with Salmonella enterica (15), 20% with E. coli (6), 6.67% with Pseudomonas spp. (2) and 23.33% with Citrobacter spp. They were highly resistant to erythromycin (83%), cefixime (82%), and amoxicillin (79%) antibiotics. On the other hand, they were sensitive against imipenem (93%) and intermediate for azithromycin (46%). Among all isolates, the most potent multidrug-resistant isolate was identified based on its 16S rRNA gene sequence, with one having the highest similarity (100%) to Citrobacter freundii strain A3.Conclusion: Poultry eggs can be a source of transmission of multidrug-resistant Citrobacter freundii from animal to human. It could be a serious health concern for developing countries since very little effort has been put into this issue.