infection control & hospital epidemiology july 2017, vol. 38, no. 7 original article
Disinfectant Susceptibility Profiling of Glutaraldehyde-Resistant Nontuberculous Mycobacteria
Winona Burgess, DVM;1 Alyssa Margolis, BS;1 Sara Gibbs, BS;1 Rafael Silva Duarte, MD, PhD;2 Mary Jackson, PhD1
objective. Activated alkaline glutaraldehyde (GTA) remains one of the most widely used high-level disinfectants worldwide. However, several reports have highlighted the potential for nontuberculous mycobacteria to develop high-level resistance to this product. Because aldehyde resistance may lead to cross-resistance to other biocides, we investigated the susceptibility profile of GTA-resistant Mycobacterium chelonae and M. abscessus isolates to various disinfectant chemistries.
methods. High-level disinfectants commonly used in the reprocessing of endoscopes and other heat-sensitive, semicritical medical equipment, including different formulations of aldehyde-based products and oxidizing agents, were tested against 10 slow- and fast-growing, GTA-susceptible and GTA-resistant, Mycobacterium isolates in suspension tests and carrier tests at different temperatures.
results. While peracetic acid– and hydrogen peroxide–based disinfectants (S40, Resert XL, Reliance DG) efficiently killed all of the Mycobacterium isolates, GTA- and ortho-phthalaldehyde-based products (ie, Cidex, Aldahol, Cidex OPA) showed variable efficacy against GTA-resistant strains despite the ability of some formulations (Aldahol) to overcome the resistance of some of these isolates, especially when the temperature was increased from 20°C to 25°C.
conclusions. Application permitting, oxidizing chemistries may provide a safe alternative to aldehyde-based products, particularly in GTA-resistant mycobacterial outbreaks.
Infect Control Hosp Epidemiol 2017;38:784–791
The rapidly growing nontuberculous mycobacteria (NTM), Mycobacterium chelonae, M. fortuitum, M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii have been associated with outbreaks and pseudo-outbreaks in healthcare settings worldwide.1–4 Infec- tions caused by M. abscessus complex strains are particularly problematic because these species are not only the most pathogenic rapidly growing mycobacteria, they are also the most antibiotic-resistant NTM, with treatment failure rates as high as 60%–70% despite years of combination therapy.5 Nosocomial outbreaks of M. abscessus subsp. massiliense
infections have reached unprecedented epidemic proportions in Brazil between 2004 and 2008 following laparoscopic sur- geries and cosmetic procedures. More than 2,000 possible cases involving 15 different states and more than 86 hospital sites have been caused by a single strain of M. abscessus subsp. massiliense named BRA100.3,4 The most striking feature of BRA100 isolates is their unusually high level of resistance to glutaraldehyde (GTA), the chemical used for disinfection of surgical instruments in all hospitals with confirmed cases.
Survival times of the BRA100 isolates exceeded 10-hour exposure to 2% GTA. This resistance phenotype was advanced as the most likely reason for the selection and dis- semination of BRA100 across the country.6 Sporadic cases of nosocomial infections and pseudoinfections caused by M. chelonae and M. abscessus isolates resistant to aldehyde- based and other high-level disinfectants have been traced to automated endoscope/bronchoscope washer disinfectors and manual dialyzer reprocessing systems in Japan, the Netherlands, the United Kingdom, and the United States.2,7–16 While the ability of rapidly growing mycobacteria to survive
and persist within treated medical devices and washers may result from their high intrinsic tolerance to biocides, involve- ment in biofilms, and association with free-living amoebae, this ability is also sometimes due to their ability to develop a high level of resistance to disinfectants, as illustrated by M. abscessus subsp. massiliense BRA100 and a recently characterized GTA- resistant M. chelonae isolate from the United Kingdom.3,17 In the latter case, defects in porin expression accounted, at least in part, for the resistance phenotype of the isolate, raising concerns
Affiliations: 1. Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins,
Colorado, United States; 2. Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. (Present affiliation: Department of Chemistry and Biochemistry, University of Colorado-Boulder, Colorado [S.G.].).
© 2017 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2017/3807-0004. DOI: 10.1017/ice.2017.75 Received December 24, 2016; accepted March 27, 2017; electronically published May 2, 2017
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