Phylogenetic Analysis and Antimicrobial Resistance Profiles of Attaching and Effacing E. coli isolated from pet birds as a possible reservoir for human diarrheagenic E. coli

Phylogenetic Analysis and Antimicrobial Resistance Profiles of Attaching and Effacing E. coli isolated from pet birds as a possible reservoir for human diarrheagenic E. coli
Mina Abbasi,¹ Seyed Mostafa Peighambari,² Jamshid Razmyar,^3,* Azam Yazdani,⁴ Fataneh Nadey Nezhad,⁵
1. University of Tehran
2. University of Tehran
3. University of Tehran
4. University of Tehran
5. University of Tehran
Introduction: Diarrhea in humans is caused by a wide variety of agents such as viruses, bacteria, and parasites. Among bacterial pathogens, Diarrheagenic Escherichia coli is one of the important causes of diarrhea. Escherichia coli (E. coli) is a gram-negative, rod-shaped, non-sporulating, and facultative anaerobic bacterium of the genus Escherichia and the family Enterobacteriaceae. Diarrheagenic strains of E. coli are divided into four main categories: 1) Enterotoxigenic E. coli (ETEC) that cause diarrhea due to enhanced intestinal secretion, 2) Enteroinvasive E. coli (EIEC) that invade intestinal cells and cause diarrhea like Shigella spp., 3) Enterohemorrhagic E. coli (EHEC) produce intestinal disease by intimate adherence to the intestinal epithelium and the development of SLT, and 4) Enteropathogenic E. coli (EPEC) are characterized by intimate adherence between the bacterium and intestinal epithelial cell membranes. Furthermore, Captive wildlife animals (such as birds) are highly susceptible to opportunistic diseases and they may be considered as a reservoir of pathogenic bacteria. Escherichia coli can be considered the most common opportunistic enterobacteria in captive animals and is associated with systemic disease in birds. The pathogenesis of enteritis by E. coli in birds is still unclear, but the presence of diarrheagenic strains may represent a public health risk. Shiga toxin-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) represent two of at least six pathotypes of human diarrheagenic E. coli (EPEC, EHEC, ETEC, EAEC, EIEC, and DAEC) that affect birds and may be considered as zoonotic pathogens. E. coli strains (EHEC and EPEC) that cause characteristic attaching and effacing (A/E) lesions in the intestinal mucosa are classified as attaching and effacing E. coli (AEEC). Our study aimed to determine attaching and effacing E. coli, evaluate their antibiotic resistance, as well as investigate their phylogroups.
Methods: In total, 200 fecal samples were collected from pet birds (belonging to 22 different species and 5 orders) referred to the avian specialty unit of the faculty of veterinary medicine hospital, University of Tehran. UspA, eae, bfpA, stx1, and stx2 gene-specific primers were utilized in PCR techniques to identify AEEC. The agar disk diffusion and MIC techniques were used to evaluate the recovered isolates' antibiotic susceptibility. Based on the Clermont phylotyping techniques, their phylogroups were examined.
Results: Nine of 26 (13%) isolated E. coli strains harbored the eae gene (three Cockatiel, two Mynah, two White-eared Bulbul, one Rose-ringed parakeet, and one Duck). The White-eared Bulbul had the highest percentage of isolated E. coli (60%), followed by Duck (37.5%), Canary (20%), Mynah and Rose-ringed parakeet (18.2%), Budgerigar (14.2%), African Grey Parrot and Lovebirds (12.5%), and Cockatiel (10.1%). None of the eae positive samples carried the bfpA gene, but five samples had both stx1 and stx2, and four samples had stx2. So, all AEEC isolates were classified as STEC based on the absence of the bfpA gene and the presence of stx1 and/or stx2 genes. All but two (duck and cockatiel) of the AEEC isolated strain phylogroups were identified by Clermont et al.’s (2019) upgraded phylogroup approach. Four B2 (Cockatiel, Mynah, Rose-ringed parakeet, and White-eared bulbul), and three D phylogroups (Cockatiel, Mynah, and White-eared bulbul) were identified. Our findings indicated that seven of the nine AEEC discovered strains exhibited multi-drug resistance (MDR).
Conclusion: Shiga-toxin-producing E. coli is one of the most significant diarrheagenic E. coli with zoonotic potential, and it should be regarded as a serious concern for the public's health. In addition to the isolation of these strains from companion birds (4.5%), as a popular pet in our country, the significant isolation of STEC from patients suffering from gastroenteritis indicates the importance of paying more attention to this agent as a risk to public health, particularly children and those people who suffer from immunosuppression diseases. Furthermore, the high rate of resistance to a wide range of antibiotics used in human medicine establishes AEEC as a considerable public health threat.
Keywords: Attaching and Effacing E. Coli, E. coli, Phylogrouping, Shiga toxin, STEC