Extended-spectrum β-lactamase (ESBL)–producing Escherichia coli have been frequently isolated from food-producing animals and pose a serious threat to human health. This study collected 195 ESBL-producing E. coli isolates from 20 chicken farms and 3 live-bird markets located in Northeast China (Heilongjiang, Liaoning, Jilin) and Jiangsu province from February 2011 to October 2013. ESBL genes, including bla _CTX-M , bla _TEM , and bla _SHV , were detected and characterized, and the susceptibilities of these strains to various antimicrobial agents were determined. One hundred ninety-one of these isolates carried 1 or more bla genes. bla _CTX-M , bla _TEM-1 , and bla _SHV-5 were identified in 183, 121, and 2 isolates, respectively. The most common bla _CTX-M genes were bla _CTX-M-15 (68 strains), bla _CTX-M-65 (41 strains), bla _CTX-M-55 (35 strains), bla _CTX-M-14 (32 strains), followed by bla _CTX-M-3 , bla _CTX-M-13 , bla _CTX-M-79 , and bla _CTX-M-101 , as well as the chimeric genes bla _CTX-M-64 , bla _CTX-M-123 , and bla _CTX-M-132 . Fifteen strains (7.7%) co-harboring CTX-M-1 group and CTX-M-9 group genes were detected in 195 ESBL-producing strains. Pulsed-field gel electrophoresis of 45 strains showed that these CTX-M-producing isolates belonged to 34 different types. To our knowledge, this is the first study to report the bla _SHV-5 gene in E. coli isolated from chickens in China. Conjugation experiments demonstrated that the bla _CTX-M and bla _TEM genes could be transferred to E. coli strain J53, while conjugative transfer of the bla _SHV-5 gene from two isolates was not detectable. bla _CTX-M genes are carried by many kinds of transferable and untypable plasmids. Our findings demonstrate that the CTX-M enzymes are predominant in both type and quantity.

Background: EHV-1 is one of the most serious viral pathogens that frequently cause abortion in horses around the world. However, so far, relatively little information is available on EHV-1 infections as they occur in China. In January 2021, during an abortion storm which occurred in Yili horses at the Chinese State Studs of Zhaosu (North Xinjiang, China), 43 out of 800 pregnant mares aborted. Results: PCR detection revealed the presence of EHV-1 in all samples as the possible cause of all abortions, although EHV-4, EHV-2 and EHV-5 were also found to circulate in the aborted fetuses. Furthermore, the partial ORF33 sequences of the 43 EHV-1 shared 99.3–100% and 99.0–100% similarity in nucleotide and amino acid sequences respectively. These sequences not only indicated a highly conserved region but also allowed the strains to group into six clusters. In addition, based on the predicted ORF30 nucleotide sequence, it was found that all the strains carried a guanine at the 2254 nucleotide position (aspartic acid at position 752 of the viral DNA polymerase) and were, therefore, identified as neuropathogenic strains. Conclusion: This study is the first one that establishes EHV-1 as the cause of abortions in Yili horses, of China. Further characterization of the ORF30 sequences revealed that all the EHV-1 strains from the study carried the neuropathogenic genotype. Totally, neuropathogenic EHV-1 infection in China’s horse population should be concerned although the virus only detected in Yili horse abortions.

Introduction: The widespread misuse of antibiotics has accelerated the emergence of multidrug-resistant bacterial strains, presenting a major threat to global public health. Bacteriophages (phages), owing to their host-specific lytic activity and self-replicating nature, have emerged as promising alternatives or adjuncts to conventional antibiotic therapies.Methods: In this study, a lytic phage targeting avian pathogenic Escherichia coli (APEC) was isolated from farm wastewater. The phage’s morphological characteristics, host range, optimal multiplicity of infection (MOI), one-step growth curve, pH stability, thermal stability, chloroform sensitivity, and in vitro antibacterial activity were determined. Subsequently, the therapeutic efficacy of the phage was evaluated in a pigeon model.Results: In this study, we isolated and characterized a lytic phage, designated vB_EcoM_P3322, from farm wastewater targeting APEC. Transmission electron microscopy classified vB_EcoM_P3322 within the Myoviridae family. The phage exhibited broad lytic activity against five Escherichia coliserotypes (O8:H10, O15:H18, O51:H20, O149:H20, and O166:H6). Optimal biological parameters included a multiplicity of infection (MOI) of 1, a latent period of 10 minutes, an 80-minute burst period, and a burst size of 252 PFUs/cell. vB_EcoM_P3322 maintained stable lytic activity across a pH range of 5–9 and temperatures from 4°C to 50°C, although it was sensitive to chloroform. In vitro, the phage effectively suppressed bacterial growth within 6 hours at MOIs of 0.1, 1, and 10. Whole-genome sequencing revealed a 151,674 bp double-stranded DNA genome encoding 279 predicted open reading frames. No virulence factors, toxin genes, antibiotic resistance genes, or lysogeny-related elements were identified, affirming its safety for therapeutic application. Phylogenetic analysis indicated 98.44% nucleotide identity (97% coverage) with phage vB_EcoM_Ro121c4YLVW (GenBank: NC_052654), suggesting a close evolutionary relationship. In a pigeon infection model, vB_EcoM_P3322 treatment significantly improved survival and reduced histopathological damage in the liver and spleen. Metagenomic analysis of duodenal contents revealed a marked reduction (P < 0.01) in E. coli abundance in the treatment group, indicating selective pathogen clearance and modulation of gut microbiota.Discussion: In summary, vB_EcoM_P3322 displays broad-spectrum lytic activity, robust environmental stability, potent antibacterial efficacy both in vitro and in vivo, and a safe genomic profile. These attributes support its potential as a novel biocontrol agent for managing APEC infections in poultry farming.