Isolation of nontuberculous mycobacteria in Zambia: eight case reports

Abstract

The isolation of nontuberculous mycobacteria (NTM) raises the question of their clinical significance, especially in an African setting. We found a high percentage of NTM isolated from various specimens, including ones that are normally sterile, among 213 patients in Zambia. Because tuberculosis can affect all parts of the body, we decided to include patients who had signs and symptoms in any part of the body for more than 2 weeks. Most patients had tractus respiratorius (80%) and tractus digestivus (10%) symptoms. During three consecutive days, sputum was collected and two separate sputum specimens were cultured for mycobacteria. Depending on the clinical picture, pleural effusion, ascites, abscess material, or enlarged lymph nodes were also cultured for mycobacteria. A specimen from one sterile body site was collected from 25 patients (60% human immunodeficiency virus [HIV] positive). NTM were isolated from 8 of these 25 specimens. Mycobacterium lentiflavum was isolated from four patients, and Mycobacterium goodii was isolated from one patient. In order to exclude the possibility of laboratory cross-contamination, a novel amplified fragment length polymorphism DNA typing method for M. lentiflavum was developed. Genetic variation was detected, rendering the likelihood of laboratory contamination unlikely. Clinically relevant infection due to NTM occurs in both HIV-positive and HIV-negative patients in Zambia, and their clinical impact seems to be underestimated. This is the first report of M. lentiflavum and M. goodii infections in Africa.

FIG. 1.

Phylogenetic tree on the basis of similarity in the 16S rRNA gene sequences and respective sequences of the mycobacterial isolates. UMS, unknown mycobacterium species.

FIG. 2.

AFLP analysis of M. lentiflavum strains. Two separate fragment patterns obtained by two amplifications steps with the primers G/AT and G/CA are demonstrated. Shown are the fingerprints for all strains listed in Table 2. Some strains are included in duplicate. The lane order is as follows (from left to right): 1, 037 UA; 2, 00-1863; 3, 037 UA; 4, 049 SpA; 5, 019 Sp2A; 6, 049 SpA; 7, 001 SpA; 8, 021 Sp2N; 9, 033 biopsy; 10, 011 U2A; 12, 062 SpN; 13, 033 Sp2A; 14, 001 SpA; 15, 01-0014; 16, 033 Sp2A; 17, 00-1863; 18, 011 U2A; 19, 033 Sp2A; 20, 01-0014; 21, 045 Plv2A; 22, M. tuberculosis. Three different types of arrows (pointing up, to the right, or to the left) identify three main marker patterns. The marker patterns are mentioned in Table 2. The arrow pointing up identifies pattern II, the arrow pointing to the right identifies pattern III, and the arrow pointing to the left identifies pattern I. The boxed regions highlight the pattern belonging to the specific arrow. Molecular weights are indicated in base pairs on the right side of the figure.