Genetic characterization of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae collected from healthy turkeys

Amel Romdhani ¹, Sana Dhaouadi ², Sarah Cheriet ¹

⁰University of Tunis El Manar, Laboratory of bacteriological research, Tunisian Institute of Veterinary Research, Bab Saadoun, Tunis 1006, Tunisia.

Journal of Infection in Developing Countries +

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April 30, 2025

View abstract on PubMed

Summary

Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-En) are prevalent in turkeys, posing a significant public health risk. These multidrug-resistant bacteria can transfer to humans through the food chain or direct contact.

Area Of Science

Veterinary Microbiology
Food Safety
Antimicrobial Resistance

Background

Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-En) in food-producing animals represent a growing public health concern.
Turkeys are a potential reservoir for ESBL-En, facilitating their transmission to humans through food and environmental pathways.

Purpose Of The Study

To investigate the prevalence and genetic characteristics of ESBL-En in healthy turkeys.
To identify antimicrobial resistance genes and mobile genetic elements associated with ESBL-En in this animal population.

Main Methods

Fecal samples from 70 healthy turkeys were analyzed for ESBL-En using selective culture media.
Antibiotic susceptibility testing was performed according to CLSI guidelines.
Polymerase chain reaction (PCR) was employed to detect genes encoding ESBLs, carbapenemases, tetracyclines, colistin, sulfonamides, quinolones, and integrons.

Main Results

45 isolates (64.3%) of ESBL-En were recovered, primarily *E. coli* (41 isolates) and *K. pneumoniae* (4 isolates).
Various *bla*CTX-M genes (e.g., *bla*CTX-M-1, *bla*CTX-M-15, *bla*CTX-M-27) were identified in *E. coli* and *K. pneumoniae*.
Resistance genes for tetracyclines (*tetA*, *tetB*), sulfonamides (*sul1*, *sul2*), fluoroquinolones (*aac(6')-Ib-cr*), and colistin (*mcr-1*, *mcr-2*) were detected, along with class 1 and 2 integrons. Five *E. coli* isolates belonged to the pandemic ST131 clone.

Conclusions

Turkeys harbor a high prevalence of multidrug-resistant (MDR) ESBL-En.
The findings underscore the potential for transmission of these resistant strains to humans via the food chain or direct contact, highlighting the need for surveillance and control measures.

Keywords:

CTX-M E. coli ESBL K. pneumoniae ST131 Turkeys