Seasonal variation in Escherichia coli bloodstream infections in northern Israel

Abstract

Seasonal variation in the infection rate with certain Gram-negative organisms has been previously described, but few studies have been published regarding Escherichia coli. The aim of this study was to investigate the incidence rate of E. coli bloodstream infection (BSI) and the association with temperature in different seasons in the Yizrael Valley. Positive blood cultures sent to the microbiology laboratory of Ha'Emek Medical Centre over a period of 8 years (January 2001 to December 2008) were included. The mean monthly temperature in the Yizrael Valley in the same period was compared with the monthly E. coli BSI rate. We divided the year into three periods: winter (December to February: mean temperature <15°C), transitional (March, April and November: mean temperature 15-19°C) and summer (May to October: mean temperature ≥20°C). In addition, we correlated the mean monthly antibiotic use in the same period measured as total defined daily doses for the whole regional population with E. coli BSI. During the study period, 2810 BSIs were recorded (35%E. coli). In 67.4% of the cases of E. coli bacteraemia, the source was urinary tract infection. The crude incidence of E. coli BSI was 4.1/1000 admissions. There was no difference in the number of cultures/month (mean: 29 ± 6). However, E. coli BSI was 19% and 21% more frequent in summer than in the transitional and winter seasons, respectively (p 0.01). The antibiotic consumption was significantly higher in the winter period. We found significantly higher rates of E. coli BSI in the summer period. Host, bacterial and ecological factors, together with high consumption of antibiotics during the winter season, could partially explain these findings.

Seasonality in Gram-negative and healthcare-associated infections

“…Regarding Gram‐negative bacilli, seasonal variations have been demonstrated for infections, mostly BSIs, caused by Acinetobacter spp., E. coli , Enterobacter cloacae , Klebsiella spp., and P. aeruginosa , with higher rates of infections during the summer months in North America, Europe, the Middle East, Australia, and Asia [4–10]. In addition, a correlation has been observed between temperature increase and rates of BSI for Acinetobacter spp., P. aeruginosa , E. coli , K. pneumonia , and S. aureus.…”

“…The other microorganisms causing HCAIs that are subject to seasonal variations are P. aeruginosa , E. coli , K. pneumoniae , Enterobacter cloacae , and S . aureus [4,6–8,10,11].…”

A Method to Assess Seasonality of Urinary Tract Infections Based on Medication Sales and Google Trends

“…Also, the method used did permit an estimate of the magnitude of the seasonal variations. Time series analyses were later performed for bloodstream infections in different countries [5], [24], [25], [26]. All these studies suggested seasonality of E. coli bloodstream infections, with summer increases ranging from 12% to 35% compared to the winter or to the rest of the year.…”

The Warmer the Weather, the More Gram-Negative Bacteria - Impact of Temperature on Clinical Isolates in Intensive Care Units

“…Data on summer peaks in the incidences of other Gram-negative bacterial infections among hospitalized patients have only recently been published [6], [7], [8]. The authors of the study by the University of Maryland reported that incidence rates for E. coli were 12 percent higher in summer than in winter.…”