Pulmonary tuberculosis: virulence of Mycobacterium africanum and relevance in HIV co-infection.
Although Mycobacterium africanum is being isolated in a significant proportion of cases of pulmonary tuberculosis in West Africa, its pathogenic potential remains a matter of discussion. Recent reports leave the question of whether M. africanum causes more severe pathology than M. tuberculosis or resembles opportunistic pathogens and might gain importance in the course of the HIV pandemic. Patients with pulmonary tuberculosis associated with M. africanum (n=556) and M. tuberculosis (n=1350) were studied in Ghana, West Africa, and compared regarding self-reported signs and symptoms, chest radiography, HIV status, mycobacterial drug resistance and mycobacterial clustering as determined by spoligotyping and IS6110 fingerprints. The rate of M. africanum infections was similar in HIV-positive (27%) and HIV-negative (30%) patients. M. africanum clustered less than M. tuberculosis (21% vs 79%; OR, 0.38; 95% CI, 0.3-0.5; p<0.001) corresponding to its lower prevalence (29% vs 70%). Clinically and radiographically, no significant differences were found except that M. africanum caused lower-lobe disease less frequently than M. tuberculosis (OR, 0.39; 95% CI, 0.2-0.7; Pc=0.01), whereby this association applied to HIV-negative patients only. No difference in virulence, as assessed by the severity of radiological presentation, was found when the two M. africanum subtypes West African 1 and West African 2 were compared. In the population studied, M. africanum closely resembled M. tuberculosis in pathology and cannot be considered an opportunistic pathogen.
Meyer
Christian G
CG
Department of Molecular Medicine, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany. c.g.meyer@bni-hamburg.de
Scarisbrick
Genevieve
G
Niemann
Stefan
S
Browne
Edmund N L
EN
Chinbuah
Margaret Amanua
MA
Gyapong
John
J
Osei
Ivy
I
Owusu-Dabo
Ellis
E
Kubica
Tanja
T
Rüsch-Gerdes
Sabine
S
Thye
Thorsten
T
Horstmann
Rolf D
RD
D017088:AIDS-Related Opportunistic Infections / Q000235:genetics / Q000276:immunology* / Q000635:transmission; D000328:Adult; D005260:Female; D005869:Ghana; D015658:HIV Infections / Q000235:genetics / Q000276:immunology* / Q000635:transmission; D006801:Humans; D008297:Male; D009161:Mycobacterium / Q000145:classification / Q000472:pathogenicity*; D013902:Radiography, Thoracic; D013183:Sputum / Q000276:immunology; D018088:Tuberculosis, Multidrug-Resistant / Q000235:genetics; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000235:genetics / Q000276:immunology* / Q000635:transmission; D014774:Virulence