Interaction between linezolid and Mycobacterium tuberculosis in an experimental in vitro model

Minimum Bactericidal Concentration Techniques in Mycobacterium tuberculosis: A Systematic Review

Minimum bactericidal concentration (MBC) assay is an accepted parameter for evaluating new antimicrobial agents, and it is frequently used as a research tool to provide a prediction of bacterial eradication. To the best of our knowledge, there is no standardization among researchers regarding the technique used to detect a drug's MBC in Mycobacterium tuberculosis. Thus, the aim of this systematic review is to discuss the available literature in determining a drug's MBC in M. tuberculosis, to find the most commonly used technique and standardize the process. A broad and rigorous literature search of three electronic databases (PubMed, Web of Knowledge, and LILACS) was performed according to the PRISMA statement. We considered studies that were published from January 1, 1990 to February 19, 2019. Google Scholar was also searched to increase the number of publications. We searched for articles using the MeSH terms "microbiological techniques," "Mycobacterium," "antibacterial agents." In addition, free terms were used in the search. The search yielded 6,674 publications. After filter application, 5,348 publications remained. Of these, we evaluated the full text of 187 publications. By applying the inclusion criteria, 69 studies were included in the present systematic review. In the literature analyzed, a great variety in the techniques used to determine a drug's MBC in M. tuberculosis was observed. The most common variability is related to the culture media used, culture incubation time, and the percentage of bacterial death for the drug to be considered as bactericidal. The most commonly used technique for drug's MBC determination was carried out using the drug's minimum inhibitory concentration (MIC) assay. Aliquots from prior MIC values were subcultured in Middlebrook agar and incubated for 4 weeks at 35°C for determining the colony forming unit (CFU) with relevance to detect 99.9% bacilli killed or reduction in 3 log₁₀ viable bacilli.

Linezolid in the treatment of drug-resistant tuberculosis: the challenge of its narrow therapeutic index

INTRODUCTION

Linezolid is an oxazolidinone with potent activity against M tuberculosis, and improves culture conversion and cure rates when added to treatment regimens for drug resistant tuberculosis. However, linezolid has a narrow therapeutic window, and the optimal dosing strategy that minimizes the substantial toxicity associated with linezolid's prolonged use in tuberculosis treatment has not been determined, limiting the potential impact of this anti-mycobacterial agent.

AREAS COVERED

This paper aims to review and summarize the current knowledge on linezolid for the treatment of drug-resistant tuberculosis. The focus is on the pharmacokinetic-pharmacodynamic determinants of linezolid's efficacy and toxicity in tuberculosis, and how this relates to defining an optimal dose. Mechanisms of linezolid toxicity and resistance, and the potential role of therapeutic drug monitoring are also covered. Expert commentary: Prospective pharmacokinetic-pharmacodynamic studies are required to define optimal therapeutic targets and to inform improved linezolid dosing strategies for drug-resistant tuberculosis.