A Campylobacteriosis Outbreak Caused by One Asymptomatic Food Handler Carrier.

In August 2021, three students with diarrhea from the same school visited a local hospital in the S district of Beijing. An epidemic investigation showed that there were more students with diarrhea in the same school and they had one meal together. Campylobacter jejuni was isolated from both patients with diarrhea and asymptomatic food handlers; however, the latter also carried Campylobacter coli. Phylogenomic analysis showed that there was a campylobacteriosis outbreak among the students, and the asymptomatic food handler may have been the source of the infection. Routine inspection and surveillance for Campylobacter is needed for the food producing staff, particularly those cooking in the cafeteria in schools or other public food services.

Genetic and Phenotypic Variation of Campylobacter jejuni NCTC11168 Caused by flhA Mutation during Laboratory Passage.

Objective: Campylobacter jejuni NCTC11168 is commonly used as a standard strain for flagellar biosynthesis research. In this report, two distinguished phenotypic isolates (CJ1Z, flhA mutant strain, lawn; CJ2S, flhA complemented strain, normal colony) appeared during laboratory passages for NCTC11168. Methods: Phenotypic assessments, including motility plates, transmission electron microscopy, biofilm formation assay, autoagglutination assay, and genome re-sequencing for these two isolates (CJ1Z, flhA mutant strain; CJ2S, flhA complemented strain) were carried out in this study. Results: Transmission electron microscopy revealed that the flagellum was lost in CJ1Z. Phenotypic assessments and genome sequencing of the two isolates were performed in this study. The capacity for biofilm formation, colony auto-agglutination, and isolate motility was reduced in the mutant CJ1Z. Comparative genomic analysis indicated a unique native nucleotide insertion in flhA (nt, 2154) that caused the I719Y and I720Y mutations and early truncation in flhA. Conclusion: FlhA has been found to influence the expression of flagella in C. jejuni. To the best of our knowledge, this is the first study to describe the function of the C-terminal of this protein.

Genetic Characteristics of Lipooligosaccharide and Capsular Polysaccharide of Campylobacter jejuni from Different Sources in China.

Objective: To determine the distribution of two important virulence factors [lipooligosaccharide (LOS) and capsular polysaccharide (CPS)] in Campylobacter jejuni ( C. jejuni) isolated from different sources in China and to develop a rapid screening method for Guillain-Barré syndrome (GBS)-associated strains. Methods: Whole-genome sequencing was carried out for 494 C. jejuni strains. The OrthoMCL software was used to define the LOS/CPS gene clusters. CPS genotyping was performed with serotype-specific sequence alignment using the BLAST software. Real-time Polymerase chain reaction (PCR) was developed with the unique sequences of specific CPS types. Results: Nine novel and 29 previously confirmed LOS classes were identified. LOS classes A, B, and C were the most common (48.2%, 238/494) among the 494 strains. Twenty-six capsular types were identified in 448 strains. HS2, HS4c, HS5/31, HS19, and HS8/17 were the most frequent CPS genotypes (58.7%, 263/448). Strains of 17 CPS genotypes (strain number > 5) had one or two prevalent LOS classes ( P < 0.05). Multiplex real-time PCR for rapid identification of HS2, HS19, and HS41 was developed and validated with strains of known serotypes. Conclusion: Our results describe the genetic characteristics of the important virulence factors in C. jejuni strains in China. The multiplex real-time PCR developed in this study will facilitate enhanced surveillance of GBS-associated strains in China.

Genetic Characteristics and Antimicrobial Susceptibility of Arcobacter butzleri Isolates from Raw Chicken Meat and Patients with Diarrhea in China.

Arcobacter is an emerging foodborne pathogen worldwide. In this study, the prevalence, antimicrobial susceptibility and genetic characteristics of Arcobacter from different sources were investigated. Eighteen A. butzleri isolates were obtained from 60 raw chicken meat samples (16/60, 27%) and 150 patients with diarrhea (2/150, 1.3%). The resistance ratios to nalidixic acid, ciprofloxacin, clindamycin, chloramphenicol, and florfenicol were 83.33% (15/18), 38.89% (7/18), 38.89% (7/18), 33.33% (6/18) and 33.33% (6/18), respectively. We performed whole genome sequencing of the 18 isolates, and we predicted antibiotic resistance genes and virulence factors by using assembled genomes through blastx analysis. Two resistance genes, bla OXA-464 and tet(H), and the C254T mutation in gyrA, were identified in the genomes of some resistant isolates. Furthermore, virulence genes, such as flgG, flhA, flhB, fliI, fliP, motA, cadF, cjl349, ciaB, mviN, pldA and tlyA, were found in all strains, whereas hecA, hecB and iroE were found in only some strains. Phylogenetic tree analysis of A. butzleri isolates on the basis of the core-genome single nucleotide polymorphisms showed that two isolates from patients with diarrhea clustered together, separately from the isolates from raw chicken and the chicken strains. This study is the first comprehensive analysis of Arcobacter isolated in Beijing.