Background: Nontuberculous mycobacteria (NTM) can cause infections in both human immunodeficiency virus (HIV)-infected and HIV-noninfected patients. The incidence of NTM infections has been increasing since the acquired immunodeficiency syndrome (AIDS) epidemics. However, the epidemiologic and clinical data of NTM infections in Thailand are limited.

Objective: Determine the epidemiology, clinical manifestations, treatment, and outcome of NTM infections in King Chulalongkorn Memorial Hospital from January 2000 to December 2003.

Material and Method: One hundred and fourteen patients had positive NTM cultures; however, complete medical records were available in only 103 (90.3%) patients.

Results: There were 71 (68.9%) HIV-infected patients, and 38 (87%) of them had the CD4 counts of <200 cells/L (range 4-360). Among HIV-infected patients, the most common previous opportunistic infections included tuberculosis (36.6%), Pneumocystis jirovecii pneumonia (25.3%), cryptococcal meningitis (15.5%), penicilliosis (5.6%), and cytomegalovirus infection (5.6%). Most patients presented with prolonged fever (67%), chronic cough (54.4%), lymphadenopathy (52.4%), weight loss (50.5%), or chronic diarrhea (31%). The clinical manifestations included disseminated (17.4%) and localized (82.6%) infections. The localized infection included pulmonary infection (82.3%), followed by gastrointestinal infection (34.1%), skin infection (12.9%), lymphadenitis (8.2%), genitourinary tract infection (2.4%), central nervous system infection (2.4%), and keratitis (1.2%). Mycobacterium avium complex (MAC) was the predominant species (48.5%), followed by M. kansasii (19.4%), and rapidly growing mycobacteria (16.4%). Diffuse reticular infiltration was most commonly observed on chest radiography (53.4%). Abnormal laboratory findings included anemia (48.5%), hyponatremia (42.7%), and elevated alkaline phosphatase (39.8%). The overall mortality rate was 34.8% (45.9% and 11.1% in HIV- and HIV-noninfected patients).

Conclusion: A diagnosis of NTM infection requires a high index of suspicion in patients especially with AIDS or immunocompromised status who present with prolonged fever, with or without organ-specific symptoms and signs. Therefore, clinical specimens must be sent for mycobacterial cultures for a definite diagnosis, a determination of the species of NTM, and an appropriate management. In addition to four standard antituberculous drugs, clarithromycin should be added for the treatment of MAC in patients with AIDS who presented with disseminated opportunistic infections before obtaining the microbiologic results.

Keywords: Nontuberculous mycobacteria (NTM), HIV, AIDS, Mycobacterium avium complex, Mycobacterium kansasii, Rapidly growing mycobacteria