title: Seasonal and ascending trends in the incidence of carriage of extended-spectrum ß-lactamase-producing Escherichia coli and Klebsiella species in 2 German hospitals.
abstract: BACKGROUND
  Extended-spectrum ß-lactamase (ESBL)-producing strains of bacteria have become a major public health concern. In the present study, the incidence of carriage of ESBL-producing strains was analyzed for general trends and seasonality.
  
  
  METHODS
  Monthly data on ESBL-producing strains were collected retrospectively at 2 large university hospitals in Germany. The mean monthly temperatures for the 2 settings were collected from Germany's national meteorological service. Multivariable time series analyses were performed to explain variations in the monthly incidence densities of carriage of ESBL-producing bacteria (number of cases involving ESBL-producing Escherichia coli and/or Klebsiella species per 1,000 patient days). For the final models, we incorporated variables for the ascending linear trends and other variables representing the mean monthly temperature.
  
  
  RESULTS
  Our models demonstrated that there was an increasing trend in the incidences of carriage of ESBL-producing bacteria. In addition, the incidences of carriage of all ESBL-producing bacteria responded positively to the mean temperature, meaning that during the summer, more cases involving ESBL-producing bacteria were detected than during the winter. The same methodology was also applied to the incidence of methicillin-resistant Staphylococcus aureus carriage, but no association was found with the mean temperature.
  
  
  CONCLUSIONS
  In the present study, we demonstrated that the monthly incidence of carriage of ESBL-producing bacteria was highly correlated with the mean monthly temperature, a fact that should be considered in experimental studies as an additional parameter influencing the incidence of ESBL-producing bacteria.
authors.affiliation: Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany. klaus.kaier@uniklinik-freiburg.de
authors.forename: Klaus
authors.initials: K
authors.lastname: Kaier
authors.forename: Uwe
authors.initials: U
authors.lastname: Frank
authors.forename: Andreas
authors.initials: A
authors.lastname: Conrad
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Meyer
mesh_terms: D003428:Cross Infection; D004926:Escherichia coli / Q000201:enzymology*; D004927:Escherichia coli Infections / Q000453:epidemiology; D005858:Germany / Q000453:epidemiology; D006746:Hospital Bed Capacity, 500 and over; D006785:Hospitals, University; D006801:Humans; D007709:Klebsiella / Q000201:enzymology*; D007710:Klebsiella Infections / Q000453:epidemiology; D011159:Population Surveillance; D012189:Retrospective Studies; D012621:Seasons; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases