CTX-M and TEM as Predominant Types of Extended Spectrum β-Lactamases Among Serratia marcescens Isolated From Solid Organ Recipients

Abstract Background Serratia marcescens is an important pathogen in hospital infections since organisms resistant to multiple antimicrobials pose a special threat particularly among transplant patients. The aim of this work was to assess the number of strains producing β-lactamases with extended spectrum (ESBL) among S. marcescens isolated from our patients. Materials and Methods We investigated S. marcescens isolated from 2005 to 2008 for ESBL. The phenotype methods were applied and additionally we chose strains for polymerase chain reactions using primers for the most popular types of ESBL. Results Over the investigated time, 257 patients were infected with S. marcescens with 188 (73%) displaying an ESBL-positive phenotype. A Molecular analysis showed that most of them produced both CTX-M and TEM β-lactamases. In the last year, the percentage of ESBL-producing strains decreased, but also in the last year, we isolated S. marcescens resistant to carbapenems from three patients. Conclusions The CTX-M type of ESBL predominated among ESBLs produced by strains of S. marcescens. The appearance of strains resistant to carbapenems is alarming.