Dataset Information

Metabolic activity of mature biofilms of Mycobacterium tuberculosis and other non-tuberculous mycobacteria.

ABSTRACT: Mycobacteria are classified into two groups, fast- and slow-growing. Often, fast-growing mycobacteria are assumed to have a higher metabolic activity than their slower counterparts, but in mature biofilms this assumption might not be correct. Indeed, when measuring the metabolic activity of mycobacterial biofilms with two independent non-invasive techniques (isothermal microcalorimetry and tunable diode laser absorption spectrometry), mature biofilms of slow- and fast-growing species appeared more alike than expected. Metabolic heat production rate was 2298?±?181?µW for M. smegmatis and 792?±?81?µW for M. phlei, while M. tuberculosis and M. bovis metabolic heat production rates were between these values. These small differences were further confirmed by similar oxygen consumption rates (3.3?±?0.2 nMole/s and 1.7?±?0.3 nMole/s for M. smegmatis and M. tuberculosis, respectively). These data suggest that the metabolic potential of slow-growing mycobacterial biofilms has been underestimated, particularly for pathogenic species.

SUBMITTER: Solokhina A

PROVIDER: S-EPMC5569076 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Metabolic activity of mature biofilms of Mycobacterium tuberculosis and other non-tuberculous mycobacteria.

Solokhina Anna A Brückner David D Bonkat Gernot G Braissant Olivier O

Scientific reports 20170823 1

Mycobacteria are classified into two groups, fast- and slow-growing. Often, fast-growing mycobacteria are assumed to have a higher metabolic activity than their slower counterparts, but in mature biofilms this assumption might not be correct. Indeed, when measuring the metabolic activity of mycobacterial biofilms with two independent non-invasive techniques (isothermal microcalorimetry and tunable diode laser absorption spectrometry), mature biofilms of slow- and fast-growing species appeared mo ...[more]

PMID: 28835629

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Project description:Tuberculosis (TB) occurs in a wide range of mammalian species and thus poses a health risk to humans living or working in close proximity with TB infected animals. Despite a high incidence of M. bovis infections in domestic or wildlife species tuberculosis infections in rhinoceros have so far been very limited. Over the past 53 years, tuberculosis of the respiratory tract has been confirmed in just 22 rhinoceros, most of those infected not by M. bovis but M. tuberculosis. However, because of the zoonotic risk TB testing is recommended or becomes even mandatory in endangered species. The dilemma in rhinoceros and many other wildlife species; non-validated tests are highly inconsistent in their ability to identify TB infection. Current lack of TB diagnostics may result in TB positive rhinoceros living with the infection, transmitting it to those around them or in euthanasia of animals found unconfirmed at necropsy. This is an unacceptable diagnostic status considering that some species are critically endangered and therefore should not be euthanized in order to confirm suspicion of disease. To overcome this shortcoming we used bronchoscopy to detect mycobacteria in respiratory fluids of TB suspicious rhinoceros. Fluids from seven, TB suspicious white rhinoceros were harvested during 21 bronchoscopies. Our new approach: In addition to bacterial culture a dual quantitative PCR system tested for the general presence of DNA from NTM and more specifically for DNA from MTC. Both, bacterial culture and qPCR were negative for MTC in respiratory fluids of all rhinoceros (7/7). At the same time, respiratory fluids from six rhinoceros tested positive for the presence of NTM or other closely related bacteria (6/7). M. tuberculosis was found only once in an oesophageal aspirate. The high incidence of mycobacterial DNA in the respiratory tract suggests that white rhinoceros, as strict grazers, are immensely exposed to environmental bacteria of this genus. Presence of NTM in the respiratory or intestinal system could possibly cause false positive results in intradermal tests. A wider use of bronchoalveolar lavage is warranted to further elucidate immunologic response to NTM and exposure to, incidence and prevalence of MTC infections in rhinoceros.

Project description:Reactive multi-target 'fragment drugs' represent critical components of current tuberculosis regimens. These compounds, such as pyrazinamide, are old synthetic antimycobacterials that are activated inside Mycobacterium tuberculosis bacilli and are smaller than the usual drug-like, single-target molecules. Based on the success of small 'dirty' drugs in the chemotherapy of tuberculosis, we suggested previously that fragment-based whole cell screens should be introduced in our current antimycobacterial drug discovery efforts. Here, we carried out such a screen and characterized bactericidal activity, selectivity and spectrum of hits we obtained. A library of 1725 fragments was tested at a single concentration for growth inhibitory activity against M. bovis BCG as screening strain and 38 of 116 primary hits were confirmed in dose response analyses to be active against virulent M. tuberculosis. Bacterial kill experiments showed that most hits displayed bactericidal activity at their minimal inhibitory concentration. Cytotoxicity assays established that a large proportion of hits displayed a favorable selectivity index for mammalian cells. Importantly, one third of M. tuberculosis active fragments were also active against M. abscessus and M. avium, two emerging non-tuberculous mycobacterial (NTM) pathogens, opening the opportunity to develop broad spectrum antimycobacterials. Activity determination against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa) bacteria, as well as fungi (Candida albicans, Cryptococcus neoformans) showed only a small overlap indicating a generally narrow spectrum of these novel antimicrobial hits for mycobacteria. In conclusion, we carried out the first fragment-based whole cell screen against bacteria and identified a substantial number of hits with excellent physicochemical properties and dual activity against M. tuberculosis and NTM pathogens. These hits will now be evaluated in animal models of mycobacterial infection to determine whether any of them can be moved forward as a new antimycobacterial fragment drug candidate.

Dataset Information

Metabolic activity of mature biofilms of Mycobacterium tuberculosis and other non-tuberculous mycobacteria.

Publications

Metabolic activity of mature biofilms of Mycobacterium tuberculosis and other non-tuberculous mycobacteria.

Similar Datasets

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