P2-142 Extended-Spectrum Beta-Lactamase-producing Escherichia coli from Meconium of Newborn Calves

Tuesday, July 11, 2017
Exhibit Hall (Tampa Convention Center)
Lin Teng , University of Florida , Gainesville , FL
Peixin Fan , University of Florida , Gainesville , FL
Amber Ginn , University of Florida , Gainesville , FL
Joseph Driver , University of Florida , Gainesville , FL
KwangCheol Casey Jeong , University of Florida , Gainesville , FL
Introduction:  Extended-spectrum β-lactamase (ESBL)-producing Escherichia colihas become a great concern to public health primarily because of its resistance to third-generation cephalosporins, which are widely used in human healthcare facilities to treat bacterial infections. Although it is controversial, it is commonly believed that food animals acquire antimicrobial resistant (AMR) bacteria by receiving antibiotic treatments.

Purpose:  The purpose of this study was to identify the earliest time when animals are exposed to ESBL-producing E. coli.

Methods: Meconium samples were collected from the rectal anal junction of 322 newborn calves. ESBL-producing E. coli were identified from the samples by plating on MacConkey agar supplemented with Cefotaxime (4 µg/mL). Isolates were further characterized with ChromAgar E. coli and CTX-M gene amplification using PCR. Illumina MiSeq was employed for Whole Genome Sequencing (WGS) of 37 strains from 24 calves. After assembly using SPAdes2.0, nineteen representative strains were selected, based on their Sequencing Types (STs) and whole genome architecture, for further bioinformatics analyses and antimicrobial susceptibility test.

Results: ESBL-producing E. coli was detected in 7.5% (24/322) of meconium samples of newborn calves. Following WGS, phylogenetic analysis revealed that these strains clustered into 8 groups that coincided with their STs. All the isolates carried a variety of virulence genes and were resistant to multiple antibiotics, suggesting that these strains may threaten public health if they contaminate food products. In particular, we identified hyper-virulent strains of ST117 that harbored Shiga toxin-encoding genes (stxAB), which may cause severe human diseases.

Significance:  This was the first study that accessed the prevalence and characterization of ESBL-producing E. coli in meconium of newborn calves, indicating animals are even start to be exposed to AMR bacteria in the uterus.