Determination of the Antibiotic Resistance Rates of <i>Serratia marcescens</i> Isolates Obtained from Various Clinical Specimens

Abstract

Aim: Serratia marcescens clinical isolates are increasingly resistant to antibiotics. Therefore, the treatment of infections caused by S. marcescens becomes difficult. The aim of this study was to examine the antimicrobial resistance profiles of S. marcescens bacteria isolated from various clinical specimens according to body regions and clinics and to evaluate for enzyme production rates associated with antibiotic resistance of these isolates.

Materials and Methods: Blood culture samples were incubated in a fully automated BACTEC‑FX system. Identification and antibiogram processing was carried out by fully automated VITEK 2 identification and antibiogram system. The obtained results were retrospectively screened.

Results: S. marcescens was identified in a total of 158 clinical specimens. The departments where S. marcescens was most commonly identified were the Anesthesia Intensive Care Unit (25.9%), followed by Chest Diseases (19.6%). Serratia isolates were most commonly determined in blood culture (35.4%) and sputum culture (24.6%). Resistance rates to ceftriaxone and ceftazidime were 22.7% and 19.6%, respectively. However, the rate of  resistance detected to cefotaxime and gentamicin (0.6%) was very low.

Conclusion: Clinical isolates of Serratia exhibited highest resistance to ceftriaxone, ceftazidime, and piperacillin/tazobactam. However, it was found that the tested Serratia strains did not exhibit high resistance to other antibiotics. Our results suggest that cefotaxime and gentamicin are the most suitable antibiotics for treatment. The extended‑spectrum  β‑lactamase and inducible β‑lactamase ratios were found to be decreased by 6%–7%. Although different results may be obtained from different hospitals and regions, it should not be forgotten that Serratia strains may be resistant to many antibiotics and that the results of antibiotic  susceptibility testing may help plan antibiotic treatment.

Keywords: Antibiotic resistance, antibiotic susceptibility, Serratia marcescens