Risk factors for community-acquired urinary tract infections caused by ESBL-producing enterobacteriaceae--a case-control study in a low prevalence country

Abstract

Community-acquired urinary tract infection (CA-UTI) is the most common infection caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, but the clinical epidemiology of these infections in low prevalence countries is largely unknown. A population based case-control study was conducted to assess risk factors for CA-UTI caused by ESBL-producing E. coli or K. pneumoniae. The study was carried out in a source population in Eastern Norway, a country with a low prevalence of infections caused by ESBL-producing Enterobacteriaceae. The study population comprised 100 cases and 190 controls with CA-UTI caused by ESBL-producing and non-ESBL-producing E. coli or K. pneumoniae, respectively. The following independent risk factors of ESBL-positive UTIs were identified: Travel to Asia, The Middle East or Africa either during the past six weeks (Odds ratio (OR) = 21; 95% confidence interval (CI): 4.5-97) or during the past 6 weeks to 24 months (OR = 2.3; 95% CI: 1.1-4.4), recent use of fluoroquinolones (OR = 16; 95% CI: 3.2-80) and β-lactams (except mecillinam) (OR = 5.0; 95% CI: 2.1-12), diabetes mellitus (OR = 3.2; 95% CI: 1.0-11) and recreational freshwater swimming the past year (OR = 2.1; 95% CI: 1.0-4.0). Factors associated with decreased risk were increasing number of fish meals per week (OR = 0.68 per fish meal; 95% CI: 0.51-0.90) and age (OR = 0.89 per 5 year increase; 95% CI: 0.82-0.97). In conclusion, we have identified risk factors that elucidate mechanisms and routes for dissemination of ESBL-producing Enterobacteriaceae in a low prevalence country, which can be used to guide appropriate treatment of CA-UTI and targeted infection control measures.

Figure 1. Selection of study population.

^aDementia (n = 1), unable to reach by phone (n = 2) and death (n = 2).

Figure 2. Decreasing risk^a of ESBL-positive urinary tract infection with increasing number of fishmeals per week^b.

^aControlling for the variables: Travelling to Asia, Middle east or Africa, Use of fluoroquinolones the past 90 days, Use of β-lactams except mecillinam the past 90 days, Diabetes mellitus,Recreational freshwater swim past year and age. ^bReference category: eating ≤1 fishmeal per week.