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Identification of Rare Bacterial Pathogens by 16S rRNA Gene Sequencing and MALDI-TOF MS
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Serratia marcescens isolated in 2005 from clinical specimens from patients with diminished immunity

A Młynarczyk1, G Młynarczyk, J Pupek

  • 1Department of Medical Microbiology, Warsaw Medical University, Warsaw, Poland. grazyna.mlynarczyk@am.edu.pl

Transplantation Proceedings
|November 21, 2007
PubMed

Insights

Serratia marcescens strains in a transplant institute showed high antibiotic resistance, likely due to extended spectrum beta-lactamases (ESBLs) and AmpC production. Two resistant clones spread, with one resistant to all but carbapenems.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Clinical Pharmacy

Background:

  • Serratia marcescens is a significant cause of hospital-acquired infections.
  • Antibiotic resistance in S. marcescens poses a major challenge in clinical settings, particularly in immunocompromised patients.

Purpose of the Study:

  • To compare the antibiotic resistance patterns of S. marcescens strains isolated from patients in different wards of a transplantation institute.
  • To investigate the mechanisms of beta-lactam antibiotic resistance, including extended spectrum beta-lactamases (ESBLs) and AmpC production.

Main Methods:

  • Retrospective analysis of 81 S. marcescens strains isolated in 2005 from patients across 3 wards and 1 clinic.
  • Phenotypic characterization of antibiotic resistance profiles.
  • Estimation of the prevalence of ESBL and AmpC production.

Main Results:

  • High levels of resistance to multiple antibiotics were observed in the isolated S. marcescens strains.
  • Extended spectrum beta-lactamases (ESBLs) were likely produced by 63.2%–84.6% of strains, and approximately 30% were probable derepressed AmpC producers.
  • Evidence suggested the circulation of at least two distinct resistant S. marcescens clones, with varying resistance patterns, including resistance to nitrofurantoin in all strains.

Conclusions:

  • S. marcescens strains in this transplantation institute exhibit significant and concerning antibiotic resistance.
  • The prevalence of ESBL and AmpC producers, alongside the emergence of resistant clones, highlights the need for strict infection control measures.
  • Limited therapeutic options, primarily carbapenems and piperacillin/tazobactam for specific clones, underscore the severity of the resistance challenge.

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