A Population-Based Surveillance Study of Shared Genotypes of Escherichia coli Isolates from Retail Meat and Suspected Cases of Urinary Tract Infections

Abstract

There is increasing evidence that retail food may serve as a source of Escherichia coli that causes community-acquired urinary tract infections, but the impact of this source in a community is not known. We conducted a prospective, population-based study in one community to examine the frequency of recovery of uropathogenic E. coli genotypes from retail meat samples. We analyzed E. coli isolates from consecutively collected urine samples of patients suspected to have urinary tract infections (UTIs) at a university-affiliated health service and retail meat samples from the same geographic region. We genotyped all E. coli isolates by multilocus sequence typing (MLST) and tested them for antimicrobial susceptibility. From 2016 to 2017, we cultured 233 E. coli isolates from 230 (21%) of 1,087 urine samples and 177 E. coli isolates from 120 (28%) of 427 retail meat samples. Urine samples contained 61 sequence types (STs), and meat samples had 95 STs; 12 STs (ST10, ST38, ST69, ST80, ST88, ST101, ST117, ST131, ST569, ST906, ST1844, and ST2562) were common to both. Thirty-five (81%) of 43 meat isolates among the 12 STs were from poultry. Among 94 isolates in the 12 STs, 26 (60%) of 43 retail meat isolates and 15 (29%) of 51 human isolates were pan-susceptible (P < 0.005). We found that 21% of E. coli isolates from suspected cases of UTIs belonged to STs found in poultry. Poultry may serve as a possible reservoir of uropathogenic E. coli (UPEC). Additional studies are needed to demonstrate transmission pathways of these UPEC genotypes and their food sources.IMPORTANCE Community-acquired urinary tract infection caused by Escherichia coli is one of the most common infectious diseases in the United States, affecting approximately seven million women and costing approximately 11.6 billion dollars annually. In addition, antibiotic resistance among E. coli bacteria causing urinary tract infection continues to increase, which greatly complicates treatment. Identifying sources of uropathogenic E. coli and implementing prevention measures are essential. However, the reservoirs of uropathogenic E. coli have not been well defined. This study demonstrated that poultry sold in retail stores may serve as one possible source of uropathogenic E. coli This finding adds to a growing body of evidence that suggests that urinary tract infection may be a food-borne disease. More research in this area can lead to the development of preventive strategies to control this common and costly infectious disease.

Keywords: Escherichia coli; extraintestinal diseases; molecular epidemiology; multidrug resistance; multilocus sequence typing; urinary tract infection; uropathogenic E. coli.

FIG 1

Geographic distribution of local retail markets in Northern California, where retail meat product sampling was performed in 2016 to 2017. The light-green circle shows the location of the Contra Costa County Public Health Laboratory. The blue circle represents the location of the university-affiliated health care service. Red circles represent the locations of local markets where meat samples were purchased.

FIG 2

Distribution of multilocus sequence types of E. coli isolates obtained in Northern California from patients suspected to have UTI seen at the university health service (A) and from retail meat products (B).

FIG 3

Venn diagram of the multilocus sequence genotypes of E. coli isolates obtained in Northern California from retail meat products and patients with urinary tract infections.

FIG 4

Population snapshot of E. coli isolates obtained in Northern California from patients suspected to have UTIs seen at the university health service and retail meat products. Genetic relationships among 395 E. coli isolates from human urine samples and retail meat products were visualized by the goeBURST algorithm based on the PHYLOViZ software (http://www.phyloviz.net/). Each circle represents a distinct genotype; the size of a circle is proportional to the number of isolates. Representative STs are shown as numbers without the ST prefix. The numbers in squares represent the shared genotypes (sequence type without the ST prefix) between urine and meat E. coli isolates. STs that are single-locus variants are connected with thick black lines. STs that are double-locus variants are connected with thin black lines. STs that are different at three or more loci are connected with dotted lines. Gray shading indicates that more than two STs belong to one clonal complex. (A) Isolates from three source groups (human urine samples, poultry meat samples, and pork and beef samples). (B) Isolates from two source groups (human urine samples and poultry meat samples).