The Rate and Resistance Profiles of Serratia spp. Among Other Bacteria Isolated from Blood Cultures

Abstract

INTRODUCTION: Serratia genus, especially Serratia marcescens, has become one of the important cause of hospital infections in the last five decades. There is a limited number of publications on Serratia spp, which cause sporadic infections or outbreaks in intensive care unit patients, especially pediatric patients. The aim of this study was to investigate the antibiotic resistance profiles of the Serratia genus and detection rates among blood cultures. METHODS: Blood samples were incubated in the BD BACTEC FX (Becton Dickinson, USA) system. Samples were subcultured on 5% sheep blood agar (SBA) and eosin methylene blue (EMB) agar when the system detected growth. After incubation for 16-24 hours at 35+-2°C, the grown isolates on SBA and EMB agar were identified by mass spectrometry with MALDI Biotyper 3 (Bruker Daltonics, USA). Antimicrobial susceptibilities were studied with BD Phoenix 100 (Becton Dickinson, USA) system. RESULTS: Among 9730 agents isolated from blood cultures over a six-year period, 69 (0.7%) were identified as Serratia genus, 58 of them being S. marcescens. Of Serratia spp. isolated patients, 37 (54%) were children and 47 (68%) were intensive care unit patients. A total of 20 isolates (29%) were resistant to at least one of the carbapenems tested. The most effective antibiotics against Serratia species were found as trimethoprim-sulfamethoxazole, ciprofloxacin, and amikacin with resistance rates of 3%, 4%, and 7%, respectively. DISCUSSION AND CONCLUSION: Serratia species were isolated from blood cultures at a rate of seven per thousand in a six-year period, and high carbapenem resistance in isolates was noteworthy.

Keywords

• serratia
• drug resistance
• blood culture
• carbapenems