Trends in Colistin Resistance and Multidrug-Resistant Phenotypes Among Gram-Negative Bacilli: A Retrospective...

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Colistin is a critical last-resort antibiotic for multidrug-resistant Gram-negative bacilli (MDR-GNB).
• Increasing colistin resistance among clinical isolates poses a significant threat to its therapeutic efficacy.
• Effective surveillance of resistance trends is crucial for guiding treatment strategies and public health interventions.

Purpose of the Study:

• To evaluate colistin resistance trends in Gram-negative bacilli (GNB) over a five-year period.
• To identify species with the highest prevalence of colistin resistance.
• To inform antimicrobial stewardship and infection control policies.

Main Methods:

• Analysis of 23,143 Gram-negative bacilli (GNB) clinical isolates from a large Emergency Hospital in North-Eastern Romania.
• Species-specific evaluation of colistin resistance, focusing on Enterobacterales and non-fermenting GNB.
• Identification of distinct resistance phenotypes and assessment of annual resistance rates.

Main Results:

• Overall colistin resistance was 3.98% among the analyzed GNB strains.
• Klebsiella spp. demonstrated the highest resistance prevalence (>80% of resistant strains), with annual rates between 12.97% and 21.64%.
• Low resistance was observed in Escherichia coli (0.18-1.25%), Pseudomonas spp. (<1%), and Acinetobacter spp. (5.43%), with Citrobacter spp. showing no resistance in the last three years.

Conclusions:

• A persistent presence of colistin resistance, particularly in Klebsiella spp., necessitates ongoing surveillance.
• While resistance in some species remains low, the emergence of resistant strains highlights the need for robust antimicrobial stewardship.
• Effective infection control policies are essential to mitigate the spread of colistin-resistant GNB.