Nontuberculous mycobacteria (NTM) are a diverse group of environmental mycobacteria which cause a wide range of pathology, from lung disease to skin and soft tissue (SST) infections and disseminated disease, mostly in immunocompromised individuals. The antimicrobial susceptibility is variable with high rates of resistance for some subspecies . Distinction between pathogenic and non pathogenic isolates is often difficult.
We conducted a retrospective review of medical records of patients older than 18 who had an NTM isolated in specimens other than lung, sputum, bronchial lavage, pleural fluid/tissue, between 1/2012 and 12/2016 at Banner University Medical Center Tucson, Arizona.
We identified a total of 33 patients meeting our inclusion criteria. Most common sources were SST in 9 cases (27%), bone and joint in 9 (27%), followed by stool -5/33 (15%), blood -4 (12%), sinus 4 (12%) and disseminated (blood and bone marrow) in 1 case and brain tissue in 1 case. The predominant isolates were Mycobacterium (M.) chelonae- 6/33 (18%), M. avium complex- 5/33 (15%), M. abscessus - 5/33 (15%). None of the stool and sinus isolates were considered pathogenic and treated. Most common presentation was fever 7/33 (21%) and skin rash 7/33 (21%). Only 13/33 (39%) patients received specific treatment for the NTM (SST infection 5/9, bone and joint 3/9, blood 3/4, disseminated 1/1, brain tissue 1/1). Of the 13 treated infections, 9 (70%)were foreign body associated; the hardware was removed in all cases except 2 (1 blood isolate associated with prosthetic valve endocarditis and 1 brain tissue). Susceptibilities were available for 19 isolates. All M. abscessus were resistant to at least 4 drugs but none were resistant to amikacin. For the rapid growers, no standard starting treatment was identified. No pattern of laboratory abnormalities (WBC, hemoglobin, AST, alk phos, ESR, CRP) could be identified.
Our study shows that extrapulmonary NTM infections remain rare. There was no correlation between the NTM species and clinical significance or severity of disease. Furthermore, in the absence of specific clinical or laboratory features, the decision to treat is largely based on clinical judgment.
A. Georgescu, None
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