Proteus mirabilis infections in a secondary-care hospital in Oman: epidemiology, antimicrobial resistance, and predictors of in-hospital mortality

Abstract Background Proteus mirabilis is an important opportunistic pathogen in healthcare settings, but data from secondary-care hospitals in Oman remain limited. Objective The aim of this study was to describe the epidemiology and antimicrobial resistance profile of laboratory-confirmed P. mirabilis infections in a secondary-care hospital in Oman and to identify predictors of multidrug-resistant organism (MDRO) infection and in-hospital mortality. Methods We conducted a retrospective cross-sectional study at Sohar Hospital, Oman, including all laboratory-confirmed P. mirabilis infection episodes from January to December 2022. After episode-level deduplication, 193 unique infection episodes were analysed. Demographic, clinical and microbiological data were extracted from hospital records. Antimicrobial susceptibility testing was interpreted according to CLSI criteria. Univariable and multivariable logistic regression analyses were performed to identify predictors of MDRO infection and in-hospital mortality. Results The cohort was predominantly male (64.8%) with a median age of 63 years. Wound swabs were the most common specimen source (53.4%), followed by urine (22.3%) and endotracheal secretions (13.0%). MDRO prevalence was 39.4%, comprising ESBL-producing isolates (14.0%), CRE (12.4%) and MDR-only phenotypes (13.0%). In-hospital mortality was 26.4% and was higher in MDRO-positive than non-MDRO infections (38.2% vs. 18.8%). Third-generation cephalosporins showed very poor activity among tested isolates, whereas piperacillin-tazobactam retained the best susceptibility among adequately tested agents. Male sex independently predicted MDRO infection (aOR 3.81). Any comorbidity (aOR 13.56), ICU admission (aOR 8.43) and MDRO infection (aOR 2.66) independently predicted mortality. Conclusions In this single-centre secondary-care cohort, P. mirabilis infections showed a substantial MDRO burden and clinically important in-hospital mortality. These findings support strengthened surveillance, antimicrobial stewardship and targeted infection-prevention measures, particularly in clinically documented wound-care and critical-care settings, while recognising the retrospective design and absence of molecular resistance confirmation.