Mortality and Outcomes of Patients Infected with Extensively Drug-Resistant Bacteria Admitted to Intensive Care Units

Abstract

Background: The emergence of antimicrobial-resistant pathogens in intensive care units (ICU) makes treatment of these infections very difficult. Objectives: This study aimed to survey the resistance phenotype, risk factors, and possible treatment options for hospital-acquired infections (HAI) at ICUs in a referral university hospital. Methods: Samples were prepared from ICU patients with HAIs. Pathogens were isolated, and the resistance phenotype, prescribed antibiotics, mortality rate, associated risk factors, and clonal relationship of the isolates were assessed. Results: From 100 patients admitted to ICUs, 76 (76%) showed clinical symptoms of HAIs. The most common sources of infection were lung secretions (51.8%). The isolated bacteria were Gram-negative (77, 90.6%) and Gram-positive (9.4%). The most common isolated microorganism was the Acinetobacter baumannii complex (63.5%). The most effective antimicrobials were colistin (96.1%) and linezolid (100%) for Gram-negative and Gram-positive isolates, respectively. An extensively drug-resistant (XDR) phenotype was documented in all isolates of A. baumannii, Pseudomonas aeruginosa, and Serratia marcescens. The XDR phenotype was a significant risk factor only for mortality. A. baumannii had the highest mortality rate (66.6%) among all the isolates. While A. baumannii strains had limited diversity, the other species were highly divergent. Conclusions: The results revealed a high mortality rate for Gram-negative isolates, especially in adenosine triphosphate-binding cassette (ABC). The high genetic similarities of ABC strains might be an indication of neglecting infection control prevention. The use of cotrimoxazole and colistin instead of carbapenems can be promising for mortality reduction in the studied ICUs.