Clinical importance of gram-negative bacteria with inducible chromosomal beta-lactamase in the medical-surgical intensive care unit

Ferran Navarro, Carles Alonso, Josep Ballús, Elisenda Miró, Francesca March, Pere Coll, Beatriz Mirelis

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)

Abstract

Background: The aim of the study was to determine the frequency of third-generation cephalosporins and aztreonam resistance in gram-negative bacteria with inducible chromosomal beta-lactamase (βLac-ind) after beta-lactam therapy in the medical-surgical intensive care unit (ICU) at a university-affiliated hospital. Patients and methods: We studied 34 infections in 29 patients admitted to the ICU. All were infected by strains with βLac-ind and all were treated with beta-lactam antibiotics. Susceptibility was determined by disc-diffusion. The beta-lactamase activity of those strains showing constitutive beta-lactamase overproduction were characterized by isoelectrofocusing. When this derepression occurred during the therapy, the strains were compared by genomic macrorestriction (PFGE). Results: In 29 out of 34 infections the initial strains was susceptible. In 11 cases, the culture were not negativized in spite of their susceptible pattern. In 4 cases there was derepression during therapy. In 5 cases the initial strains were derepressed. The microorganisms isolated more frequently were Pseudomonas aeruginosa (22 cases) and Enterobacter cloacae (5 cases). The beta-lactamase activity detected correspond well with a βLac-ind. In those cases with derepression during therapy, the initial susceptible strain and the resistant strain were identical by PFGE. Conclusions: The percentage of bacteria that were derepressed either initially or following therapy was 26%. Derepression was detected more frequently in patients treated with cephalosporins. These results reflect the importance of this resistance mechanism in those strains subject to strong selective pressure.
Original languageEnglish
Pages (from-to)171-176
JournalEnfermedades Infecciosas y Microbiologia Clinica
Volume14
Issue number3
Publication statusPublished - 1 Mar 1996

Keywords

  • antibioticotherapy
  • beta-lactam
  • inducible chromosomal beta-lactamase
  • intensive care unit
  • selective pressure

Fingerprint Dive into the research topics of 'Clinical importance of gram-negative bacteria with inducible chromosomal beta-lactamase in the medical-surgical intensive care unit'. Together they form a unique fingerprint.

Cite this