Multidrug-Resistant Extraintestinal Pathogenic <i>Escherichia coli</i> Exhibits High Virulence in Calf Herds: A Case Report
Extraintestinal pathogenic <i>Escherichia coli</i> (ExPEC) is a group of <i>Escherichia coli</i> strains that can cause severe infectious diseases outside the gastrointestinal tract, such as urinary tract infections, meningitis, septicemia, etc. We report a case of a calf her...
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-02-01
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| Series: | Microbiology Research |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2036-7481/16/3/59 |
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| Summary: | Extraintestinal pathogenic <i>Escherichia coli</i> (ExPEC) is a group of <i>Escherichia coli</i> strains that can cause severe infectious diseases outside the gastrointestinal tract, such as urinary tract infections, meningitis, septicemia, etc. We report a case of a calf herd infection by ExPEC with high rates of morbidity and mortality. The research purpose of this study was to thoroughly investigate the characteristics of the ExPEC responsible for the calf herd infection. Specifically, we aimed to understand the mechanisms underlying its multidrug resistance and high pathogenicity. Clinical samples were collected for the isolation and identification of ExPECs, cultured on MacConkey agar, and further tested by PCR for the <i>uidA</i> gene, 16S rRNA gene sequencing, and adhesion patterns on HEp-2 cells. The antimicrobial activity was determined using the disk diffusion method according to Clinical & Laboratory Standards Institute (CLSI) guidelines. The pathogenicity was assessed through the experimental infection of Kunming mice, tracking their survival and weight changes, and performing autopsies for bacterial counts and histopathological analysis. Additionally, whole-genome sequencing (WGS) and a comprehensive analysis were performed, including multilocus sequence typing (MLST), serotyping, drug-resistance gene analysis, virulence factor analysis, metabolic pathway analysis, and enrichment analysis, using various online tools and databases. An ExPEC strain named RZ-13 was responsible for this case and was identified as ST345 and O134: H21. Among the 14 antibiotics tested, 13 showed resistance, indicating that the RZ-13 strain is a multidrug-resistant (MDR) bacterium. The experimental infection of Kunming mice proved the greater pathogenicity of RZ-13 than that of CICC 24186. The comprehensive WGS revealed the presence of 28 antibiotic resistance genes and 86 virulence-related genes in the genome of the strain, corroborating its clinical manifestations of MDR and high pathogenicity. Our study isolated a MDR ExPEC strain, RZ-13, with a strong pathogenicity. This is the first case report of ExPEC leading to severe mortality in calf herds in China, underscoring the need for the rational use of antibiotics to reduce the risk of the generation and transmission of MDR bacteria from food-producing animals to ensure food safety and public health. |
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| ISSN: | 2036-7481 |