title: Antibiotic consumption and its influence on the resistance in Enterobacteriaceae.
abstract: BACKGROUND
  Increasing bacterial resistance to antibiotics is one of the most serious problems in current medicine. An important factor contributing to the growing prevalence of multiresistant bacteria is application of antibiotics. This study aimed at analyzing the development of resistance of Enterobacteriaceae to selected beta-lactam, fluoroquinolone and aminoglycoside antibiotics in the University Hospital Olomouc and assessing the effect of selection pressure of these antibiotics.
  
  
  METHODS
  For the period between 1 January 2000 and 31 December 2011, resistance of Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae and Proteus mirabilis to third- and fourth-generation cephalosporins, meropenem, piperacillin/tazobactam, fluoroquinolones and aminoglycosides was retrospectively studied. For the assessment of selection pressure of antibiotics, a parameter of defined daily dose in absolute annual consumption (DDDatb) based on the ATC/DDD classification and in relative annual consumption (RDDDatb) as the number of defined daily doses per 100 bed-days was used. The relationship between frequency of strains resistant to a particular antibiotic and antibiotic consumption was assessed by linear regression analysis using Spearman's correlation. The level of statistical significance was set at p < 0.05.
  
  
  RESULTS
  A total of 113,027 isolates from the Enterobacteriaceae family were analyzed. There was a significant effect of selection pressure of the primary antibiotic in the following cases: piperacillin/tazobactam in Klebsiella pneumoniae, gentamicin in Klebsiella pneumoniae and Escherichia coli and amikacin in Escherichia coli and Enterobacter cloacae. Also, there was significant correlation between resistance to ceftazidime and consumption of piperacillin/tazobactam in Klebsiella pneumoniae and Escherichia coli. No relationship was found between consumption of third- and fourth-generation cephalosporins and resistance to ceftazidime or between fluoroquinolone consumption and resistance to ciprofloxacin.
  
  
  CONCLUSIONS
  The study showed the effects of both direct and indirect selection pressure on increasing resistance to gentamicin, amikacin, piperacillin/tazobactam and ceftazidime. Given the fact that no correlation was found between resistance to fluoroquinolones and consumption of either primary or secondary antibiotics, we assume that the increasing resistance to fluoroquinolones is probably due to circulation of resistance genes in the bacterial population and that this resistance was not affected by reduced use of these antibiotics.
authors.affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 3, 775 15 Olomouc, Czech Republic. miroslava.htoutou@seznam.cz.
authors.forename: Miroslava Htoutou
authors.initials: MH
authors.lastname: Sedláková
authors.forename: Karel
authors.initials: K
authors.lastname: Urbánek
authors.forename: Vladimíra
authors.initials: V
authors.lastname: Vojtová
authors.forename: Hana
authors.initials: H
authors.lastname: Suchánková
authors.forename: Peter
authors.initials: P
authors.lastname: Imwensi
authors.forename: Milan
authors.initials: M
authors.lastname: Kolář
mesh_terms: D000617:Aminoglycosides / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D016972:Enterobacter cloacae / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D004756:Enterobacteriaceae Infections / Q000188:drug therapy* / Q000382:microbiology; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D024841:Fluoroquinolones / Q000627:therapeutic use; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D016014:Linear Models; D008826:Microbial Sensitivity Tests; D011513:Proteus mirabilis / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D047090:beta-Lactams / Q000627:therapeutic use
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D047090:beta-Lactams