Non-tuberculous Mycobacterium spp. are ubiquitous in the environment and cause infections and pseudo-infections in health care settings throughout the world. Among these, the rapidly-growing Mycobacterium (RGM) species, M. abscessus (subsp. abscessus and subsp. massiliense), M. chelonae, and M. fortuitum are particularly problematic due to their ubiquitous presence in hospitals'water sources and the difficulty of treating the infections they cause. There is increasing awareness of M. abscessus subspp. abscessus and massiliense in particular as emerging pathogens. Of particular concern is the increasing frequency with which glutaraldehyde-resistant RGM are being associated with nosocomial outbreaks, sometime reaching epidemic proportions as recently documented in Brazil. Glutaraldehyde (GTA) is the most widely used chemical disinfectant for heat-sensitive medical devices in hospitals worldwide. What is known of the mode of action of this disinfectant in other bacteria suggests that changes in the surface-exposed composition of the cel envelope resulting in decreased binding and/or penetration of GTA may be one of the mechanisms through which RGM develop high levels of resistance. Because of the important role played by the mycobacterial outer membrane in drug susceptibility and host-pathogen interactions, there is thus some concern that the widespread use of GTA and related aldehyde disinfectants in clinical settings is impacting on the selection of resistant populations of RGM with possible consequences on cross-resistance to drugs and pathogenicity. In support of these assumptions, we recently demonstrated that reduced porin expression was one of the mechanisms through which M. smegmatis and M. chelonae develop high levels of resistance to GTA and a further aldehyde disinfectant, ortho-phthalaldehyde (OPA). In part due to defects in porin expression, the GTA/OPA-resistant M. chelonae isolate under study also displayed unusually high levels of resistance to a number of drugs including rifampicin, ciprofloxacin, clarithromycin, erythromycin, vancomycin, tetracycline and linezolid. Further, our preliminary results indicate that, compared to a GTA-susceptible reference M. massiliense clinical isolate, the epidemic M. massiliense isolates from Brazil display unusual resistance to aminoglycosides and much increased pathogenicity in mice. We have assembled a collection of GTA-resistant isolates of M. chelonae and M. abscessus subsp. massiliense responsible for nosocomial infections and pseudo-infections in different regions of the world. The fact that not all of these isolates display cross-resistance to OPA (unlike the M. chelonae isolate described above) indicates that there must exist more than one mechanism of resistance to aldehyde disinfectants in mycobacteria. We propose to use our collection of clinical isolates together with a combination of genomic, transcriptomic, genetic and biochemical approaches to investigate the molecular mechanisms of resistance of RGM to aldehyde-based disinfectants and to study the potential impact the phenotypic changes undergone by these strains might have had on their susceptibility to drugs and pathogenicity. The results of this study could lead to the implementation of optimized strategies for the disinfection of medical devices and suggest more efficient treatments to cure those nosocomial infections caused by disinfectant-resistant isolates.

Public Health Relevance

We propose to elucidate the mechanisms of resistance of nosocomial rapidly-growing mycobacterial pathogens to aldehyde disinfectants and to study the impact of the phenotypic changes undergone by resistant isolates on their susceptibility to drugs and pathogenicity.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI089718-04
Application #
8644781
Study Section
Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
Program Officer
Boyce, Jim P
Project Start
2011-03-03
Project End
2016-02-29
Budget Start
2014-03-01
Budget End
2015-02-28
Support Year
4
Fiscal Year
2014
Total Cost
$319,891
Indirect Cost
$93,224
Name
Colorado State University-Fort Collins
Department
Microbiology/Immun/Virology
Type
Schools of Veterinary Medicine
DUNS #
785979618
City
Fort Collins
State
CO
Country
United States
Zip Code
80523
Calado Nogueira de Moura, Vinicius; Gibbs, Sara; Jackson, Mary (2014) Gene replacement in Mycobacterium chelonae: application to the construction of porin knock-out mutants. PLoS One 9:e94951
Tettelin, Hervé; Davidson, Rebecca M; Agrawal, Sonia et al. (2014) High-level relatedness among Mycobacterium abscessus subsp. massiliense strains from widely separated outbreaks. Emerg Infect Dis 20:364-71
De Groote, Mary Ann; Gibbs, Sara; de Moura, Vinicius Calado Nogueira et al. (2014) Analysis of a panel of rapidly growing mycobacteria for resistance to aldehyde-based disinfectants. Am J Infect Control 42:932-4
Ovrutsky, Alida R; Chan, Edward D; Kartalija, Marinka et al. (2013) Cooccurrence of free-living amoebae and nontuberculous Mycobacteria in hospital water networks, and preferential growth of Mycobacterium avium in Acanthamoeba lenticulata. Appl Environ Microbiol 79:3185-92
Davidson, Rebecca M; Hasan, Nabeeh A; de Moura, Vinicius Calado Nogueira et al. (2013) Phylogenomics of Brazilian epidemic isolates of Mycobacterium abscessus subsp. bolletii reveals relationships of global outbreak strains. Infect Genet Evol 20:292-7
Davidson, Rebecca M; Reynolds, Paul R; Farias-Hesson, Eveline et al. (2013) Genome Sequence of an Epidemic Isolate of Mycobacterium abscessus subsp. bolletii from Rio de Janeiro, Brazil. Genome Announc 1:
Shang, Shaobin; Gibbs, Sara; Henao-Tamayo, Marcela et al. (2011) Increased virulence of an epidemic strain of Mycobacterium massiliense in mice. PLoS One 6:e24726