Core Genome MLST for Source Attribution of Campylobacter coli

Campylobacter species are among the leading foodborne bacterial agents of human diarrheal illness. The majority of campylobacteriosis has been attributed to Campylobacter jejuni (85% or more), followed by Campylobacter coli (5–10%). The distribution of C. jejuni and C. coli varies by host organism, indicating that the contribution to human infection may differ between isolation sources. To address the relative contribution of each source to C. coli infections in humans, core genome multilocus sequence type with a 200-allele difference scheme (cgMLST200) was used to determine cgMLST type for 3,432 C. coli isolated from food animals (n = 2,613), retail poultry meats (n = 389), human clinical settings (n = 285), and environmental sources (n = 145). Source attribution was determined by analyzing the core genome with a minimal multilocus distance methodology (MMD). Using MMD, a higher proportion of the clinical C. coli population was attributed to poultry (49.6%) and environmental (20.9%) sources than from cattle (9.8%) and swine (3.2%). Within the population of C. coli clinical isolates, 70% of the isolates that were attributed to non-cecal retail poultry, dairy cattle, beef cattle and environmental waters came from two cgMLST200 groups from each source. The most common antibiotic resistance genes among all C. coli were tetO (65.6%), blaOXA–193 (54.2%), aph(3′)-IIIa (23.5%), and aadE-Cc (20.1%). Of the antibiotic resistance determinants, only one gene was isolated from a single source: blaOXA–61 was only isolated from retail poultry. Within cgMLST200 groups, 17/17 cgMLST200-435 and 89/92 cgMLST200-707 isolates encoded for aph(3’)-VIIa and 16/16 cgMLST200-319 harbored aph(2’)-If genes. Distribution of blaOXA alleles showed 49/50 cgMLST200-5 isolates contained blaOXA–498 while blaOXA–460 was present in 37/38 cgMLST200-650 isolates. The cgMLST200-514 group revealed both ant(6)-Ia and sat4 resistance genes in 23/23 and 22/23 isolates, respectively. Also, cgMLST200-266 and cgMLST200-84 had GyrAT86I mutation with 16/16 (100%) and 14/15 (93.3%), respectively. These findings illustrate how cgMLST and MMD methods can be used to evaluate the relative contribution of known sources of C. coli to the human burden of campylobacteriosis and how cgMLST typing can be used as an indicator of antimicrobial resistance in C. coli.This article is published as Harrison, Lucas, Sampa Mukherjee, Chih-Hao Hsu, Shenia Young, Errol Strain, Qijing Zhang, Glenn E. Tillman, Cesar Morales, Jovita Haro, and Shaohua Zhao. "Core Genome MLST for Source Attribution of Campylobacter coli." Frontiers in Microbiology 12 (2021): 703890. DOI: 10.3389/fmicb.2021.703890. Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted

Genotypic and Phenotypic Characterization of Antimicrobial and Heavy Metal Tolerance in Salmonella enterica and Escherichia coli Isolates from Swine Feed Mills

Antimicrobials and heavy metals are commonly used in the animal feed industry. The role of in-feed antimicrobials on the evolution and persistence of resistance in enteric bacteria is not well described. Whole-Genome Sequencing (WGS) is widely used for genetic characterizations of bacterial isolates, including antimicrobial resistance, heavy metal tolerance, virulence factors, and relatedness to other sequenced isolates. The goals of this study were to i) use WGS to characterize Salmonella enterica (n = 33) and Escherichia coli (n = 30) isolated from swine feed and feed mill environments; and ii) investigate their genotypic and phenotypic antimicrobial and heavy metal tolerance. Salmonella isolates belonged to 10 serovars, the most common being Cubana, Senftenberg, and Tennessee. E. coli isolates were grouped into 22 O groups. Phenotypic resistance to at least one antimicrobial was observed in 19 Salmonella (57.6%) and 17 E. coli (56.7%) isolates, whereas multidrug resistance (resistant to ≥3 antimicrobial classes) was observed in four Salmonella (12%) and two E. coli (7%) isolates. Antimicrobial resistance genes were identified in 17 Salmonella (51%) and 29 E. coli (97%), with 11 and 29 isolates possessing genes conferring resistance to multiple antimicrobial classes. Phenotypically, 53% Salmonella and 58% E. coli presented resistance to copper and arsenic. All isolates that possessed the copper resistance operon were resistant to the highest concentration tested (40 mM). Heavy metal tolerance genes to copper and silver were present in 26 Salmonella isolates. Our study showed a strong agreement between predicted and measured resistances when comparing genotypic and phenotypic data for antimicrobial resistance, with an overall concordance of 99% and 98.3% for Salmonella and E. coli, respectively

Interactions of organic acids with Campylobacter coli from swine.

Campylobacter coli is a bacterial species that is a major cause of diarrheal disease worldwide, and Campylobacter spp. are among the top 5 foodborne pathogens in the United States. During food production organic acids (OAs) are often used to remove bacteria from animal carcasses. The interactions of six OAs with 111 C. coli strains obtained from swine and retail pork chops were studied by determining the molar minimum inhibitory concentrations (MICMs) of the C. coli strains, and the pH at the MICMs. The Henderson-Hasselbalch equation was used to calculate the concentrations of the undissociated and dissociated OAs at the MICMs of the C. coli strains. The results for the 111 different C. coli strains obtained from different locations were treated as a single group for each OA since many of the C. coli strains behaved similarly to each different OA. Inhibition of C. coli was not dependent on pH or on the undissociated OA species, but C. coli inhibition correlated with the dissociated OA species. Therefore, if the concentration of the dissociated OAs decreases from optimum, one may then expect that C. coli bacteria would escape disinfection. The concentration of the dissociated OA should be carefully controlled in a carcass wash. We suggest maintaining a concentration of the dissociated acetic, butyric, citric, formic, lactic and propionic acids at 29, 23, 11, 35, 22 and 25 mM, respectively, when using a carcass wash with these OAs to remove C. coli bacteria. However, due to C. coli utilization of acetate, formate, lactate and propionate, these four OAs may not be the best choice to use for a carcass wash to remove C. coli contamination. Of the six OAs, citric acid was the most efficient at inhibiting C. coli

Prevalence of Antimicrobial Resistance in Select Bacteria From Retail Seafood—United States, 2019

In 2019, the United States National Antimicrobial Resistance Monitoring System (NARMS) surveyed raw salmon, shrimp, and tilapia from retail grocery outlets in eight states to assess the prevalence of bacterial contamination and antimicrobial resistance (AMR) in the isolates. Prevalence of the targeted bacterial genera ranged among the commodities: Salmonella (0%-0.4%), Aeromonas (19%-26%), Vibrio (7%-43%), Pseudomonas aeruginosa (0.8%-2.3%), Staphylococcus (23%-30%), and Enterococcus (39%-66%). Shrimp had the highest odds (OR: 2.8, CI: 2.0-3.9) of being contaminated with at least one species of these bacteria, as were seafood sourced from Asia vs. North America (OR: 2.7; CI: 1.8-4.7) and Latin America and the Caribbean vs. North America (OR: 1.6; CI: 1.1-2.3) and seafood sold at the counter vs. sold frozen (OR: 2.1; CI: 1.6-2.9). Isolates exhibited pan-susceptibility (Salmonella and P. aeruginosa) or low prevalence of resistance (<10%) to most antimicrobials tested, with few exceptions. Seafood marketed as farm-raised had lower odds of contamination with antimicrobial resistant bacteria compared to wild-caught seafood (OR: 0.4, CI: 0.2-0.7). Antimicrobial resistance genes (ARGs) were detected for various classes of medically important antimicrobials. Clinically relevant ARGs included carbapenemases (bla IMI-2, bla NDM-1) and extended spectrum β-lactamases (ESBLs; bla CTX-M-55). This population-scale study of AMR in seafood sold in the United States provided the basis for NARMS seafood monitoring, which began in 2020

Whole-Genome Sequencing of Gentamicin-Resistant Campylobacter coli Isolated from U.S. Retail Meats Reveals Novel Plasmid-Mediated Aminoglycoside Resistance Genes

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