Antimicrobial Resistance Pattern, Predisposing Factors, and Outcome of Serratia Infection in Patients Treated at a Secondary-Care Hospital in Oman: A 5-Year Retrospective Study.

Background: Serratia has emerged as an important nosocomial opportunistic pathogen, often associated with serious infections. We investigated the antimicrobial resistance trends, predisposing factors, and infection outcomes associated with Serratia species isolated in a secondary-care hospital in Oman.

Materials and methods: A retrospective study was conducted at a secondary-care hospital in the northern region of Oman after receiving approval from the research ethics and approval committee of Oman. The relevant data of patients diagnosed with Serratia infection during 2017-2021 was extracted from the Sohar Hospital health records. We statistically analyzed the data using the statistical software STATA version 14.

Results: A total of 257 non-duplicate Serratia strains were studied. S. marcescens was the predominant (79.4%) isolated species. Serratia strains were more frequently isolated from males (51.4%). The most affected were older people aged > 60 years (29.4%), infants (28%), and patients treated at critical care units. Serratia has demonstrated high resistance to beta-lactams. The susceptibility rates of Serratia strains to tigecycline, ciprofloxacin, trimethoprim-sulfamethoxazole, gentamicin, amikacin, piperacillin-tazobactam, imipenem, and meropenem was high. Septicemia, pneumonia, mechanical ventilation, and hemodialysis were the independent risk factors for increased mortality among studied subjects (P < 0.05).

Conclusions: Our study results recommend empirical therapy with trimethoprim-sulfamethoxazole, piperacillin-tazobactam, aminoglycosides, and ciprofloxacin as first-line drugs for Serratia infection. The emergence of ESBL producers and carbapenem-resistant strains is worrisome. Regular updating of physicians' knowledge about antimicrobial profiles, antibiotic prescription policies, and infection control measures is necessary to combat antimicrobial resistance and improve outcomes.