Dataset Information

Expression of antimicrobial drug tolerance by attached communities of Mycobacterium tuberculosis.

ABSTRACT: There is an urgent need to improve methods used to screen antituberculosis drugs. An in vitro assay was developed to test drug treatment strategies that specifically target drug-tolerant Mycobacterium tuberculosis. The H37Rv strain of M. tuberculosis survived antimicrobial treatment as attached microbial communities when maintained in tissue culture media (RPMI-1640) with or without lysed human peripheral blood leukocytes. When cultured planktonically in the presence of Tween-80, bacilli failed to form microbial communities or reach logarithmic phase growth yet remained highly susceptible to antimicrobial drugs. In the absence of Tween, bacilli tolerated drug therapy by forming complex microbial communities attached to untreated well surfaces or to the extracellular matrix derived from lysed human leukocytes. Treatment of microbial communities with DNase I or Tween effectively dispersed bacilli and restored drug susceptibility. These data demonstrate that in vitro expression of drug tolerance by M. tuberculosis is linked to the establishment of attached microbial communities and that dispersion of bacilli targeting the extracellular matrix including DNA restores drug susceptibility. Modifications of this in vitro assay may prove beneficial in a high-throughput platform to screen new antituberculosis drugs especially those that target drug-tolerant bacilli.

SUBMITTER: Ackart DF

PROVIDER: S-EPMC4361083 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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Expression of antimicrobial drug tolerance by attached communities of Mycobacterium tuberculosis.

Ackart David F DF Hascall-Dove Laurel L Caceres Silvia M SM Kirk Natalie M NM Podell Brendan K BK Melander Christian C Orme Ian M IM Leid Jeff G JG Nick Jerry A JA Basaraba Randall J RJ

Pathogens and disease 20140224 3

There is an urgent need to improve methods used to screen antituberculosis drugs. An in vitro assay was developed to test drug treatment strategies that specifically target drug-tolerant Mycobacterium tuberculosis. The H37Rv strain of M. tuberculosis survived antimicrobial treatment as attached microbial communities when maintained in tissue culture media (RPMI-1640) with or without lysed human peripheral blood leukocytes. When cultured planktonically in the presence of Tween-80, bacilli failed ...[more]

PMID: 24478060

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Project description:ABSTRACT The chronic nature of tuberculosis (TB), its requirement of long duration of treatment, its ability to evade immune intervention, and its propensity to relapse after drug treatment is discontinued are reminiscent of other chronic, biofilm-associated bacterial diseases. Historically, Mycobacterium tuberculosis was grown as a pellicle, a biofilm-like structure, at the liquid-air interface in a variety of synthetic media. Notably, the most widely administered human vaccine, BCG, is grown as a pellicle for vaccine production. However, the molecular requirements for this growth remain ill defined. Here, we demonstrate that keto-mycolic acids (keto-MA) are essential for pellicle growth, and mutants lacking in or depleted of this MA species are unable to form a pellicle. We investigated the role of the pellicle biofilm in the reduction of antibiotic sensitivity known as drug tolerance using the pellicle-defective ?mmaA4 mutant strain. We discovered that the ?mmaA4 mutant, which is both pellicle defective and highly sensitive to rifampicin (RIF) under planktonic growth, when incorporated within the wild-type pellicle biofilm, was protected from the bactericidal activity of RIF. The observation that growth within the M. tuberculosis pellicle biofilm can confer drug tolerance to a drug-hypersensitive strain suggests that identifying molecular requirements for pellicle growth could lead to development of novel interventions against mycobacterial infections. Our findings also suggest that a class of drugs that can disrupt M. tuberculosis biofilm formation, when used in conjunction with conventional antibiotics, has the potential to overcome drug tolerance. IMPORTANCE Two of the most important questions in tuberculosis (TB) research are (i) how does Mycobacterium tuberculosis persist in the human host for decades in the face of an active immune response and (ii) why does it take six months and four drugs to treat uncomplicated TB. Both these aspects of M. tuberculosis biology are reminiscent of infections caused by organisms capable of forming biofilms. M. tuberculosis is capable of growing as a biofilm-like structure called the pellicle. In this study, we demonstrate that a specific cell wall component, keto-mycolic acid, is essential for pellicle growth. We also demonstrate that a strain of M. tuberculosis that is both drug sensitive and pellicle defective exhibits commensal behavior and becomes drug tolerant by becoming part of a heterogeneous pellicle, a characteristic of multispecies biofilms. These observations could have important implications for identifying novel pathways for M. tuberculosis drug tolerance and the design of new modalities to rapidly treat TB.

Dataset Information

Expression of antimicrobial drug tolerance by attached communities of Mycobacterium tuberculosis.

Publications

Expression of antimicrobial drug tolerance by attached communities of Mycobacterium tuberculosis.

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