EMERGENCE OF COLISTIN RESISTANCE OF MDR ACINETOBACTER SPP. IN HOSPITAL SUNGAI BULOH DURING COVID-19 PANDEMIC

Abstract

Intro: Acinetobacter calcoaceticus – A.baumannii complex is an opportunistic pathogen that has emerged as one of the multidrug resistant organism frequently associated with nosocomial infections especially causing ventilator- associated pneumonia (VAP). Colistin and Polymyxin B are currently being used as salvage therapy for treating MDR Acinetobacter spp. However, the emergence of resistance of colistin has been reported and treatment is further complicated by poor lung tissue penetration. Thus, we implied to explore on the prevalence of its resistance in our own facility, being the national COVID-19 referral hospital. Methods: This is a cross-sectional retrospective analysis of MDR Acinetobacter spp. done for isolates of 2019 and 2021. Only clinically significant isolates were sent to Institute of Medical Research (IMR) for colistin susceptibility testing by broth microdilution. The identification of the isolates was performed by Bruker® MALDI-ToF. CLSI breakpoints were used to determine susceptibility, applying the change of breakpoints interpretation in year 2020. Findings: In 2021, out of 203 isolates, 195 (96%) were Acinetobacter baumannii. Other spp. isolated were A. nosocomialis (6, 3%) and A. proteolyticus (2, 1%). Out of that, 107 (52.7%) were resistant with MIC of >4 ug/ml and 96 (47.3 %) were intermediate with MIC of 4 ug/ml and 52% were susceptible with MIC <2 ug/ml. Clinical characteristics of patients were analysed; previous use of carbapenem, ventilation history, length of stay, and outcome (alive or deceased). Most of patients were severely ill with majority of admissions due to Category 4-5 COVID-19 and required ventilation in critical care unit. Previous carbapenem exposure was not significantly associated with colistin resistance (p=0.936). Conclusion: Emergence of colistin resistant MDR Acinetobacter spp. is alarming. Infection control measures are crucial and other therapeutic options need to be explored to improve quality of care.