Yu-Long Ye

Objective: Antibiotic resistance genes (ARGs) in bacteria are highly prevalent in the poultry industry. These genes can transfer not only within the same species but also across different species, posing significant threats to both the poultry industry and human health. However, limited research has been conducted on the prevalence and transmission links between extended-spectrum beta-lactamase (ESBL)-producing diarrheagenic Escherichia coli (E. coli) in chickens and their living environments in Shanghai’s poultry industry.Methods: In this study, 600 samples were collected from the cloacal swabs of healthy chickens and from the environments of poultry farms. These samples included feces, troughs, water containers, and soils. Antimicrobial susceptibility testing and whole-genome sequencing (WGS) were employed to characterize ESBL-producing diarrheagenic E. coli.Results: The results indicated a detection rate of E. coli at 15.67%, with the isolates exhibiting high resistance to the tested antibiotics, particularly ampicillin (AMP),nalidixic acid (NAL), chloramphenicol (CHL), and tetracycline (TET). Notably, 95.45% of the isolates were multidrug-resistant (MDR). Among these isolates, 20.45% were ESBL-producing E. coli, which exhibited higher resistance to first- through fourth-generation cephalosporins, such as cefazolin (CFZ),cefuroxime (CXM), and cefotaxime (CTX). These ESBL-producing E. coli also carried a significant number of ARGs, with bla_TEM-1B (55.56%) and bla_CTX-M-55 (38.89%) being the most prevalent on the farm. The dominant sequence type (ST) was ST1286, the prevalent serotype was O16: H32, and the dominant CH type was FumC174/FimH23. Isolates that shared the same ST types clustered together and exhibited the same serotypes and CH types.Conclusion: The findings from this study reveal that ARGs are widely distributed among ESBL-producing E. coli strains. STs with the same serotypes and FumC-FimH (CH) types showed high genetic relatedness in single-nucleotide polymorphism (SNP)-based phylogenetic analysis, highlighting the need for enhanced surveillance to prevent further transmission.

GII noroviruses are a common cause of acute gastroenteritis (AGE) outbreaks in institutional settings globally. However, AGE outbreaks caused by GI norovirus, especially the GI.5 genotype, are relatively uncommon. In February 2017, an AGE outbreak occurred in a primary school in Shanghai, China. An outbreak investigation was undertaken, and fecal specimens, rectal swabs, and environmental swabs were collected. Pathogen detection was performed and the positive specimens were characterized by gene sequencing. The descriptive epidemiological analysis suggested that this outbreak, involving 19 cases in two classes (designated classes A and B), was a small-scale propagated epidemic and person-to-person transmission was the most plausible transmission mode. The outbreak comprised two peaks, with 15 cases occurring in class A during the main peak and four cases occurring in class B in the subsequent minor peak. The primary attack rate was 38% and the secondary attack rate was 10%. Univariable logistic regression indicated that contacting a suspect case was a risk factor for norovirus infection, with an unadjusted OR of 5.6 (95% CI: 1.6–20.1). Six fecal specimens were positive for GI norovirus, with a single genotype, GI.5 norovirus, being involved, as characterized by genotyping. This outbreak was the first reported outbreak of GI.5 norovirus in China. This study implies that GI.5 norovirus is a potential agent of outbreaks spread by person-to-person transmission in institutional settings. The investigation highlights the importance of sensitive surveillance, timely isolation of individuals who are ill, adequate hand hygiene, and proper environmental disinfection for prevention and control of AGE outbreaks caused by norovirus.