Extended spectrum beta-lactamase-producing Enterobacteriaceae infections in hematopoietic stem cell transplant recipients: Epidemiology and molecular characterization.

Background: Extended spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) create a therapeutic challenge and have high potential for dissemination. The purpose of our study was to investigate the epidemiology of these infections in hematopoietic stem cell transplant (HSCT) recipients and to determine the genes encoding ESBL.

Material/methods: This retrospective study comprised adult patients hospitalized at the National Bone Marrow Transplant Center (NBMTC) and infected with ESBL-E post-HSCT between January 2006 and December 2016. The search for the ESBL and carbapenemase genes was performed by polymerase chain reaction (PCR) amplification. Molecular typing was performed by pulsed field gel electrophoresis (PFGE) after digestion with XbaI.

Results: Forty ESBL-E were responsible for infections in 34 HSCT recipients (3.3% of total HSCT recipients). Prior hospital stay, prior antibiotic therapy and prior colonization with ESBL-E were reported in 62.5%, 70% and 50% of the infectious episodes, respectively. The initial antibiotic treatment was appropriate in 67.7% of cases. Imipenem was the most prescribed antibiotic (64.5%). The mortality rate due to ESBL-E infection was 8.8%. The ESBL-E, isolated mainly from blood cultures (40%), belonged mostly to K. pneumoniae (n=19) and E. coli (n=17). Associated antibiotic resistance rates were 17.5% for ertapenem, 85% for ciprofloxacin and 30% for amikacin. The predominant gene encoding ESBL was bla (55%). Among the seven carbapenem-resistant strains, four had the bla gene and two the bla gene. There was no clonal relationship between the strains.

Conclusion: There was low prevalence of ESBL-E infections in HSCT recipients in our center, with no epidemic distribution but non-negligible mortality rate.