Identification and genotyping of the etiological agent of tuberculous lymphadenitis in Ethiopia.
BACKGROUND
In Ethiopia, little has been done to assess how Mycobacterium bovis has contributed to human tuberculosis, though the population routinely consumes unpasteurized milk and raw meat. The aim of this study was to determine the proportion of M. tuberculosis and M. bovis as etiological agents of tuberculous lymphadenitis (TBLN).


METHODS
Patients with lymphadenopathy (n = 171) were included in a cross-sectional study at Butajira Hospital, Southern Ethiopia. Lymph node biopsies were cultured. Patients' HIV status was identified. DNA from positive cultures was tested by PCR to identify M. bovis and M. tuberculosis. Isolates were genotyped by multiplex ligation-dependent probe amplification (MLPA) assay.


RESULTS
Among 171 patients, 156 had culture results. Of these, 107 (69%) were positive for M. tuberculosis complex (MTC). Six of the 10 HIV-positive patients were culture positive. M. tuberculosis specific sequences were identified in the DNA of each of 100 samples as assessed by RD10 targeted PCR, and each of the 95 isolates exhibited the M. tuberculosis specific TbD1 deletion by MLPA analysis. No M. bovis was identified. These results indicate that all the isolates were modern M. tuberculosis strains. Furthermore, MLPA studies confirmed that 42% of the isolates showed the Haarlem genotype and 12% displayed sequences compatible with INH resistance. No mutations conferring resistance to ethambutol or rifampicin were detected.


CONCLUSIONS
Our data showed that M. tuberculosis strains had common characteristics with strains causing pulmonary TB, which appears to be the main etiological agent of TBLN.
Beyene
Demissew
D
Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia. beyene88@gmail.com
Bergval
Indra
I
Hailu
Elena
E
Ashenafi
Senait
S
Yamuah
Lawrence
L
Aseffa
Abraham
A
Wiker
Harald G
HG
Engers
Howard
H
Klatser
Paul
P
Sviland
Lisbet
L
D015373:Bacterial Typing Techniques / Q000379:methods; D003430:Cross-Sectional Studies; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005002:Ethiopia; D005838:Genotype; D006801:Humans; D009163:Mycobacterium bovis / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods; D014388:Tuberculosis, Lymph Node / Q000382:microbiology*
D004269:DNA, Bacterial