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Beyond minimum inhibitory concentration values: clinical and diagnostic challenges of colistin heteroresistance in
Esra Taş1, Feride Mehtap Yücel2
1Faculty of Medicine, Department of Medical Microbiology, Samsun University, Samsun, Türkiye. esra.tas@samsun.edu.tr.
Abstract:
In recent years, infections caused by multidrug-resistant and particularly carbapenem-resistant Gram-negative bacteria have become a major global public health concern. In this context, the progressive limitation of therapeutic options has led to the reintroduction of polymyxin antibiotics, such as colistin, into clinical practice as last-resort agents. However, the widespread use of colistin has been accompanied by an increasing incidence of resistance, among which heteroresistance has emerged as a significant challenge for both diagnosis and treatment. Heteroresistance is defined as the presence of subpopulations within a bacterial isolate that exhibit varying levels of susceptibility to a given antibiotic. In Acinetobacter baumannii, colistin heteroresistance may result in the selection and expansion of resistant subpopulations during therapy, contributing to clinical failure, persistent infections, and recurrence. Furthermore, the inability of routine antimicrobial susceptibility testing methods to reliably detect heteroresistance may lead to its underrecognition in clinical settings, potentially resulting in inappropriate therapeutic decisions. Current evidence indicates that the prevalence of colistin heteroresistance in A. baumannii varies geographically. The findings presented in this review highlight the importance of increasing awareness of the molecular basis and clinical implications of colistin heteroresistance in A. baumannii, and emphasize the need for improved diagnostic approaches and more effective treatment strategies for both microbiologists and clinicians.
Insights
Colistin heteroresistance in Acinetobacter baumannii poses a diagnostic and treatment challenge. Early detection and new strategies are crucial to combat this growing threat from multidrug-resistant bacteria.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Multidrug-resistant Gram-negative bacteria, especially carbapenem-resistant strains, are a significant global health threat.
- Limited therapeutic options have led to the reintroduction of colistin as a last-resort antibiotic.
- Increasing colistin resistance, including heteroresistance, complicates treatment.
Purpose of the Study:
- To review the challenges posed by colistin heteroresistance in Acinetobacter baumannii.
- To highlight the clinical implications and diagnostic difficulties associated with this phenomenon.
- To emphasize the need for improved detection and treatment strategies.
Main Methods:
- Review of current scientific literature on colistin heteroresistance in Acinetobacter baumannii.
- Analysis of the molecular basis and clinical impact of heteroresistance.
- Evaluation of diagnostic limitations of standard antimicrobial susceptibility testing.
Main Results:
- Colistin heteroresistance involves subpopulations with varying susceptibility within a single bacterial isolate.
- It can lead to treatment failure, persistent infections, and recurrence in Acinetobacter baumannii.
- Standard diagnostic methods often fail to detect heteroresistance, leading to underrecognition.
Conclusions:
- Colistin heteroresistance in Acinetobacter baumannii is a growing concern with significant clinical implications.
- Improved diagnostic methods are essential for accurate identification and appropriate therapeutic decisions.
- Further research into effective treatment strategies is urgently needed to manage infections caused by heteroresistant strains.
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