Plasmid profile of extended-spectrum β-lactamase and quaternary ammonium compound E delta 1 gene held multi-resistant Shigella species isolated from raw cow milk and milk products in Egypt
Abstract Background Multi-resistant Shigella species recovered from raw cow milk and milk products has predominated all over the world especially extended spectrum β-lactamases (ESBLs) and Quaternary ammonium compound E delta 1 (qacE∆1) genes. This study was conducted to investigate the prevalence, antibiotic and disinfectant resistance phenotypes and genotypes as well as plasmid profiles of Shigella species isolated from raw cow milk and milk products in Egypt. The genotypic analysis was determined for the presence of β-lactamase encoding genes (blaTEM, blaCTX-M, blaOXA-1 and blaSHV), tetA(A) and qacE∆. Results Twenty-one (7%) of Shigella isolates (S. dysenteriae, S. flexneri and S. sonnei) were recovered with S. dysenteriae as the most predominant types. Antibiotic sensitivity tests showed 71.4% of multidrug-resistant Shigella isolates. High resistance rates were observed to tetracyclines (100%), ampicillin, amoxicillin-clavulanate (90.5%, each) and cefaclor (66.7%), whilst no resistance was detected against imipenem, sulfamethoxazole/trimethoprim, and azithromycin. Disinfectant susceptibility test of Shigella isolates revealed resistance to phenolic compound (vanillic), while 85.7% of Shigella isolates were benzalkonium chloride resistant. Uniplex PCR analysis exhibit presence of β-lactamase encoding genes (blaTEM in all isolates and blaCTX-M in 28.6% of isolates), tetA(A) in all isolates and 85.7% isolates positive for qacE∆1, while all isolates were negative for blaOXA-1 and blaSHV. All Shigella extended spectrum β-lactamase (ESBL) producers (6, 100%) were positive for blaTEM, blaCTX-M, and qacE∆1 genes. Furthermore, plasmid profiling revealed seven distinct plasmid patterns (P1-P7) ranging from 1.26 to 33.61 kb among all Shigella strains; S. dysenteriae displayed the greatest variance. The co-transfer of β-lactamase genes (blaTEM and blaCTX-M) and qacE∆1 genes was observed by conjugation. Conclusions S. dysenteriae was the most common identified types in the examined sources. Also, the findings imply the emergence of multi-resistant Shigella species either multi-resistant to antibiotics (particularly ESBL producer strains) or disinfectants in Egypt. Thus, the resistance of Shigella species should regularly be monitored and appropriate measures should be taken to manage this problem.