Except for MTB & M. leprae, generally free-living orgs ubiquitous in the environment Recovered from water, soil, domestic/wild animals, milk, and food >100 species in the genus Species vary by geography Mycobacteria
Acid fast bacillus = mycobacterium (ex for Nocardia, weakly or variably AF) Refractile GP or gram neutral rods “gram variable rods” Slightly bent, often beaded rods 2-4 microns long under 100x Over the past 15 years, labs are isolating less MTB & more NTM
Mycobacteria Isolate rates NTM isolates are more common than MTB isolates Report rates of isolates are not verified with clinical significant of the report Disease rates NTM dz is not communicable thus not reportable In industrialized countries: 1-1.8/100,000 of NTM disease vs. 3.5/100,000 of active MTB
Mycobacteria 4 groups of human pathogens MTB complex M. leprae Slow growing NTM Rapidly growing NTM IFN-g & IL-12 control mycobacteria via up-regulation of TNF-a from monocytes/macrophages
The most common disease causing NTM in the US are MAC & M. kansasii.
NTM – 4 clinical syndromes Pulmonary disease (75-94%) Older persons +/- underlying lung dz CF patients MAC, M. kansasii Disseminated disease (5%) Severely immunocompromised MAC, RGM spp. (M. abscesses, M. fortuitum, M. chelonae) Skin & soft tissue infection (2-3%) Direct inoculation M. marinum, M. ulcerans RGM spp. (may be nosocomial, surgical site infections) Superficial lymphadenitis, esp. cervical (0.4-3%) Children MAC, M. scrofulaceum
NTM lung disease MAC, M. kansasii, M. abscessus >50 years, ?M vs. F Symptoms variable, nonspecific chronic or reoccurring cough sputum production, fatigue, malaise, dyspnea, fever, hemoptysis, chest pain, wt loss more constitutional symptoms with advancing disease evaluation complicated by sx of coexisting lung disease CXR Fibrocavitary – often like MTB, but may be dense airspace dz or solitary cavity w/o cavitation Nodular/bronchietatic – typical MAC, usu. mid-lower lung fields, +/- cavitation
Treatment of NTM lung dz Indications for treatment Compatible respiratory or constitutional sx w/ XR abnormalities Plus EITHER Consistent isolation of NTM in mod- high numbers from more than one specimen of pulmonary secretions lsolation from >1 specimen if there is histological evidence of pulm parenchymal involvement Susceptibility testing & treament recs vary by species
M. simiae Clustered in Israel, Cuba, SW US Found in local tap water. Recent pseudo-outbreak in an urban Texas hospital from a contaminated water supply Usually a contaminant. Causes clinical disease in 9-21% of pts. Immunocompromised pts: AIDS, underlying lung disease Usually pulmonary dz, rare intraabdominal infections, and disseminated dz in AIDS Difficult to treat: No predictably effective drug combos & in vivo response may not correlate with in vitro response ? ATS recs clarithromycin and a fluoroquinolone (moxifloxaxin preferred). Linezolid, SMX may work
M. simiae M. simiae may be confused with MTB as it is the only niacin-positive NTM Maoz et al. compared pts in Israel with M. simiae vs MTB. Pts with M. simiae: More females, older age Higher rates of smoking, COPD, other dz (DM, CAD, cancer), immunosuppressive drugs Less HIV Blunted symptoms More noncavitary infiltrates in middle/lower lobes Most M. simiae isolates were contaminants Treatment with clarithromycin, ethambutol, rifabutin, and streptomycin (with modification for sensitivities)
References Griffith, DE et al. An offical ATS/IDSA statement: Diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respir Crit Care Med. 2007;175:367-416. Griffith, DE and Wallace, RJ. Microbiology of nontuberculous mycobacteria. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2009. Griffith, DE and Wallace, RJ. Overview of nontuberculous mycobacterial infections in HIV-negative patients. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2009. Griffith, DE and Wallace, RJ. Treatment of nontuberculous mycobacterial infections of the lung in HIV-negative patients. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2009. Maoz, C et al. Pulmonary Mycobacterium simiae infection: comparison with pulmonary tuberculosis. Eur J Clin Infect Dis. 2008;27,945-950. Samra, Z et al. Emergence of Mycobacterium simiae in respiratory specimens. Scan Infect Dis. 2005;37:838-841.