Objective: To determine clinical features of mycobacterial infections, from both MTB and NTM, in HIV-infected patients in Siriraj Hospital.

Material and Method: A retrospective study of adult HIV-infected patients in Infectious Disease Clinic, Siriraj Hospital, was conducted. Clinical characteristics and factors associated with mycobacterial infections were analyzed.

Results: Of 253 patients enrolled, 65 (25.7%) developed mycobacterial infections, in which 56 patients (86%) were tuberculosis (TB), whereas NTM was diagnosed in 9 (14%). Of these 65 patients, 45 (69.2%) were culture-proven, 14 (21.6%) were diagnosed TB by positive acid-fast bacilli smears and 6 (9.2%) were diagnosed TB by clinical response to anti-tuberculosis treatment only. Among culture-positive patients, MTB was found in 36 (80%) and NTM in 9 (20%), in which Mycobacterium avium complex (MAC) was the most common among NTM isolates (n = 5), followed by unidentifiable slowly-growing mycobacteria (n = 3) and M. fortuitum (n = 1). Among patients with MTB infection, 58.3% were disseminated. The most affected organ in patients with mycobacterial infections was lung (75%), followed by lymph node (66.7%). Factors associated with mycobacterial infections included male gender (64.6% vs. 54.3%; p = 0.026), higher HIV Viral load (1.04x106 vs. 0.3x106; p = 0.004), lower hematocrit (32.7% vs. 35.3%; p = 0.032) and higher alkaline phosphatase (ALP) (146 U/L vs. 107 U/L; p = 0.032). In contrast, Pneumocystis pneumonia (PCP) was negatively associated with mycobacterial infections in HIV-infected individuals (28.8% vs. 10.9%; p = 0.004). Favorable treatment response was 86.1% and 77.8% for MTB and NTM infection, respectively, and the 6-month mortality rates were 2.78% and 11.1% for MTB and NTM infection, respectively. In patients who received treatment for TB, 22.2% had hepatitis, 13.9% had drug allergy and 8.3% had immune reconstitution inflammatory syndrome.

Conclusion: Disseminated infection is the most common form of mycobacterial infection in HIV-infected patients, resulting in anemia and high ALP levels. PCP was negatively associated with mycobacterial infection. MAC is the most common of the NTM isolates in HIV-infected patients.

Keywords: HIV infection, Mycobactria, Tuberculosis, AIDS