Distribution of Escherichia coli Pathotypes in Poultry by Host, Clinical Relevance, and Serogroup

Abstract

Escherichia coli (E. coli) infections in poultry represent a significant disease burden, causing economic losses and posing public health risks due to their zoonotic potential. Although E. coli is generally characterized by low host specificity, the genetic diversity and acquisition of virulence factors enable the emergence of distinct pathotypes associated with different disease outcomes. In this review, the global and Türkiye-specific distribution of poultry-associated E. coli pathotypes was evaluated in terms of host species, clinical relevance, and serogroup diversity. The most frequently reported pathotypes in poultry include avian pathogenic E. coli (APEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli (STEC), and extraintestinal pathogenic E. coli (ExPEC). Among these, APEC is the most prevalent and is strongly associated with colibacillosis and systemic infections in poultry. Serogroups O1, O2, and O78 are commonly identified in APEC isolates worldwide. Notably, APEC and human-associated EXPEC-associated strains share phylogenetic and virulence gene repertoire similarities, suggesting that poultry   may act as a potential reservoir for ExPEC strains. Studies in Türkiye have also reported clinically important serogroups, such as O78 and O157 from poultry and environmental sources. ETEC strains have been reported in poultry, with serogroups such as O8 and O149 also identified among ETEC-associated isolates. EPEC strains have also been reported in poultry, with several serogroups, including O24, O25, O26, O103, and O157, described in association with EPEC. O157 is among the most frequently investigated STEC serogroups in poultry. These findings highlight the epidemiological importance of pathogenic E. coli in poultry. Integration of molecular virulence profiling into surveillance programs may improve the characterization and control of poultry-associated diseases and help elucidate the potential epidemiological relationship between APEC and ExPEC.

Keywords

• APEC
• chicken
• Escherichia coli
• pathotype
• poultry
• serogroup

Ethical Statement

This study is not subject to HADYEK permission in accordance with Article 8 (k) of the "Regulation on Working Procedures and Principles of Animal Experiments Ethics Committees”.

Kanatlılardaki Escherichia coli patotiplerinin konak, klinik önem ve serogrup bazında dağılımı

Abstract

Escherichia coli (E. coli) enfeksiyonları kanatlılarda önemli bir hastalık yükü oluşturmakta, ekonomik kayıplara yol açmakta ve zoonotik potansiyelleri nedeniyle halk sağlığı açısından risk teşkil etmektedir. E. coli, genellikle düşük konak özgüllüğü ile karakterize edilmesine rağmen, sahip olduğu genetik çeşitlilik ve virülens faktörlerini kazanabilme yeteneği, farklı hastalık tabloları ile ilişkili olan çeşitli patotiplerin ortaya çıkmasına olanak sağlamaktadır. Bu derlemede, kanatlı kaynaklı E. coli patotiplerinin küresel ve Türkiye’ye özgü dağılımı; konak türü, klinik önem ve serogrup çeşitliliği bazında değerlendirilmiştir. Kanatlılarda en sık bildirilen patotipler arasında avian patojenik E. coli (APEC), enterotoksijenik E. coli (ETEC), enteropatojenik E. coli (EPEC), Shiga toksin üreten E. coli (STEC) ve ekstraintestinal patojenik E. coli (ExPEC) yer almaktadır. Bunlar arasında, APEC en yaygın olanıdır. Kolibasilloz ve sistemik enfeksiyonlar ile ilişkilendirilmektedir. O1, O2 ve O78 serogrupları dünya genelinde APEC izolatlarında sıklıkla tanımlanmaktadır. Dikkat çekici olarak, APEC ve insan kaynaklı ExPEC suşları filogenetik yapı ve virülens gen repertuarı açısından benzerlik göstermekte olup, kanatlıların ExPEC için potansiyel bir rezervuar olabileceğini düşündürmektedir. Türkiye’de yapılan çalışmalarda da kanatlı ve çevresel örneklerden O78 ve O157 gibi klinik açıdan önemli serogruplar bildirilmiştir. ETEC genellikle O8 ve O149 serogrupları ile ilişkilendirilirken, EPEC genellikle O24, O25, O26, O103 ve O157 ile bağlantılıdır. STEC ise çoğunlukla O157 ve ilişkili serogruplarla ilişkili olup kanatlılarda daha nadir tespit edilmektedir. Bu bulgular, kanatlı üretim sistemlerinde patojenik E. coli’nin epidemiyolojik önemini ortaya koymaktadır. Etkin hastalık kontrolü ve APEC–ExPEC ilişkilerinin daha iyi anlaşılması için moleküler olarak virülens karakterizasyonunun rutin sürveyans sistemlerine entegre edilmesi gerekmektedir.

Keywords

• APEC
• tavuk
• Escherichia coli
• patotip
• kanatlı
• serogrup

Ethical Statement

Bu çalışma, "Hayvan Deneyleri Etik Kurullarının Çalışma Usulü ve İlkeleri Hakkındaki Yönetmelik"in 8. maddesinin (k) bendi uyarınca HADYEK iznine tabi değildir.

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