Antimicrobial resistance of multidrug-resistant Enterobacterales and Acinetobacter baumannii isolates to colistin in a Moroccan hospital

Background: The challenge of treating infections caused by multidrug-resistant Enterobacterales and Acinetobacter baumannii has significantly increased for medical professionals due to their resistance to conventional antibiotics. In such cases, Colistin is employed as a final line of defense. This study was aimed to determine the in-vitro efficacy of colistin against multidrug-resistant Gram-negative bacteria. Methods: The research was carried out in the Bacteriology Department of the Mohammed V Military Teaching Hospital in Rabat, Morocco. 321 isolates of multi-resistant Enterobacterales and Acinetobacter baumannii from various clinical samples were identified by standard microbiological protocols, and the Colistin minimum inhibitory concentrations value was determined using the microdilution method. Results: Of the 321 isolates included in the study, 76.3% were Enterobacterales and 23.6% were Acinetobacter baumannii. The minimum inhibitory analysis showed that 96.3% of the isolates were sensitive, while 3.7% were identified as resistant. The prevalence of resistance to colistin among multi-resistant Enterobacterales was 4.1%, and the MIC50 and MIC90 were 0.5 μg/ml and 1μg/ml respectively. Among the collected Acinetobacter baumannii isolates, the prevalence of colistin resistance was 2.6%, with the MIC50 and MIC90 of 0.5 μg/ml. Conclusion: The research indicates that colistin could be a viable treatment option for infections caused by multi-resistant Enterobacterales and Acinetobacter baumannii.