Steffen Renata Pamela Barrachini, Queiroz Beatriz, Silva Aline Tujimoto, Rocha Victoria Galdino Pavlenco, Franco Letícia Soares, Barbosa Fernanda Borges, Knöbl Terezinha
School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87, São Paulo, 05508270, Brazil.
Braz J Microbiol. 2025 May 14. doi: 10.1007/s42770-025-01686-x.
Avian pathogenic Escherichia coli (APEC) is the most common cause of omphalitis. This disease affects newborn chicks up to the 7th day of life, causing high mortality and reduced performance of broilers. The study aimed to determine the frequency of APEC occurrence in embryos and newly hatched chicks. E. coli isolates were subjected to PCR to identify the minimal predictive virulence factors, phylogenetic groups, and predictive identification of the clonal complex (CC) ST131, ST117, and ST95. The phenotypic analysis assessed the antimicrobial resistance profile. A total of 254 samples were analyzed and 60.63% (n = 154/254) were positive for E. coli, of which 35.71% (n = 55/154) were classified as APEC (60% (n = 33/55) isolated in the yolk sac of day-old chicks, 29.09% (n = 16/55) in pipped eggs and 10.91% (n = 6/55) in embryonated eggs). The B2 phylogenetic group accounted for 21.81% (n = 12/55), with an increase in the contamination by B2 strains during the incubation process, from 6.25% (n = 1) to 30.30% (n = 10). We also identified 14.54% (n = 8/55) strains for the G group. The sequence types ST131 and ST117 were observed at the same frequency (10.90%, n = 6), followed by ST95 (3.6%, n = 2). A total of 27.27% were considered multidrug-resistant strains (MDR). The highest resistance rate was amoxicillin (43.64%, n = 24) and tetracycline (25.45%, n = 14). To a lesser extent, levels of resistance to critical drugs commonly used in hatcheries were identified, such as ceftiofur (20%, n = 11) and gentamicin (7%, n = 4).
禽致病性大肠杆菌（APEC）是脐炎最常见的病因。这种疾病影响新生雏鸡直至出生后第7天，导致肉鸡高死亡率和生产性能下降。该研究旨在确定胚胎和新孵出雏鸡中APEC的发生频率。对大肠杆菌分离株进行PCR，以鉴定最小预测毒力因子、系统发育群以及对克隆复合体（CC）ST131、ST117和ST95的预测性鉴定。表型分析评估了抗菌药物耐药谱。共分析了254个样本，60.63%（n = 154/254）的样本大肠杆菌检测呈阳性，其中35.71%（n = 55/154）被归类为APEC（60%（n = 33/55）分离自一日龄雏鸡的卵黄囊，29.09%（n = 16/55）分离自啄壳蛋，10.91%（n = 6/55）分离自胚胎蛋）。B2系统发育群占21.81%（n = 12/55），在孵化过程中B2菌株的污染有所增加，从6.25%（n = 1）增至30.30%（n = 10）。我们还鉴定出G群菌株占14.54%（n = 8/55）。序列类型ST131和ST117的出现频率相同（10.90%，n = 6），其次是ST95（3.6%，n = 2）。共有27.27%的菌株被认为是多重耐药菌株（MDR）。耐药率最高的是阿莫西林（43.64%，n = 24）和四环素（25.45%，n = 14）。在较小程度上，还确定了孵化场常用关键药物的耐药水平，如头孢噻呋（20%，n = 11）和庆大霉素（7%，n = 4）。
