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TB Notes 4, 2002

Update from the Laboratory

Reports of Nontuberculous Mycobacterial Infections Increasing in Community Settings

Whether owing to actual increased incidence or simply to greater awareness by infection control officers and diagnostic laboratories, reports of disease caused by nontuberculous mycobacteria (NTM) have been increasing. In particular, NTM-associated disease appears to be rising in community settings. However, actual incidence cannot be determined since disease from NTM is not reported in most states.

NTM are ubiquitous in the environment, with water considered the main source of infection. Standard water disinfection procedures are ineffective in removing NTM, which are relatively resistant to chlorine levels found in water distribution systems. NTM thrive in the biofilms that readily form inside faucets and pipes. False outbreaks are often reported due to either contamination of medical sampling equipment or water used for diagnostic procedures. Person-to-person transmission has not been demonstrated. Humans can be exposed to infection through trauma, ingestion, or inhalation. There are approximately 90 recognized species of NTM, with over 20 known to cause disease in humans. Based on speed of growth, species have been divided into two main groups: slow growers (which include M. avium, M. intracellulare, M. kansasii, and M. marinum) and rapid growers (including M. fortuitum, M. abscessus, M. chelonae, and M. mucogenicum).

Several recent reports demonstrate the opportunistic nature and variety of community-based NTM infections:

Between April and October 2000, an outbreak in northern California of Mycobacterium fortuitum furunculosis was associated with contaminated whirlpool footbaths at a nail salon. Microtrauma from shaving the legs before receiving pedicures was determined to be a risk factor for infection among 110 customers who had furunculosis of the lower extremities. High numbers of M. fortuitum were isolated from organic debris that had accumulated behind water inlet screens of the footbaths. Identical patient and footbath isolates were identified by pulsed-field gel electrophoresis (PFGE). Disturbingly, at least six other sporadic cases of furunculosis were reported at other California nail salons. A survey of whirlpool footbaths at other California salons revealed that at least one species of potentially pathogenic mycobacteria was present in most machines. The findings from the outbreak investigation, conducted jointly by the CDC and the California Department of Health, were presented in the May 2, 2002, issue of the New England Journal of Medicine.

In May 2001, the American Academy of Ophthalmology issued an alert to its members in response to a CDC investigation of a cluster of M. chelonae keratitis cases involving four patients who underwent laser in-situ keratomileusis (LASIK) surgery. All the patients had the procedure performed at the same community-based refractive surgery center. Isolates from three patients were identical by PFGE, indicating a common source of infection. Contact lens fragments, used as masks during the procedure, were associated with infection but laboratory analysis of lenses with identical lot numbers failed to identify any contaminating organisms. The results of the investigation are reported in the December 2001 issue of the Journal of Ophthalmology.

NTM of the M. avium complex (MAC), which are estimated to infect up to 50% of patients with AIDS, are increasingly being recognized as a cause of pulmonary disease in healthy individuals who use contaminated hot tubs. Presumably, the organisms are inhaled by means of aerosols generated from the circulating action in tubs. A cluster of "hot tub lung" infections among members of a family of five in Colorado is described in the November-December 2001 issue of CDC’s Emerging Infectious Diseases. Maintaining hot tubs according to manufacturers’ directions is essential for reducing the risk of infection.

Staff of CDC and of the New York City Department of Health are currently investigating an outbreak of M. abscessus in patients who underwent a variety of unlicensed cosmetic procedures. Infections were linked to procedures done in both men and women seeking to remove wrinkles, reshape lips or noses, enlarge breasts, or simply lose weight. A Venezuelan couple, working out of an apartment on the East Side of Manhattan and a home in Queens, have been arrested and charged with performing medical treatments without a license, assault, fraud, and grand larceny. At least eight patients have been hospitalized with abscesses requiring drainage, leaving them disfigured. The investigating EIS officer, Reina M. Turcos, reported that most of the patients were immigrants from Latin America, where it is common for unlicensed physicians to perform cosmetic procedures.

Treatment of NTM disease varies by NTM species and is complicated by the fact that most species are naturally resistant to conventional antibiotics. A multidrug regimen with several antibiotics, including anti-TB drugs, is often required to achieve cure. Infections can be persistent with treatment lasting over 2 years with drug costs exceeding $5,000 a year.

—Reported by Mitchell Yakrus, M.S., M.P.H.
Div of AIDS, STD, and TB Laboratory Research, National Center for Infectious Diseases


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
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