Browsing by Author "Osei Ivy"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Pulmonary tuberculosis: Virulence of Mycobacterium africanum and relevance in HIV co-infection
    (ELSEVIER, 2008) Niemann Stefan; Gyapong John; Owusu-Dabo Ellis; Osei Ivy; Kubica Tanja....et al
    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 withM. africanum (n Z 556) and M. tuberculosis (n Z 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, 0.3e0.5; p < 0.001) corresponding to its lower prevalence (29% vs 70%).
  • No Thumbnail Available
    Item
    Unequal distribution of resistance-conferring mutations among Mycobacterium tuberculosis and Mycobacterium africanum strains from Ghana
    (ELSEVIER, 2010) Osei Ivy; Owusu-Dabo Ellis; Chinbuah Amanua; Gyapong John; Niemann Stefan.....et al
    Isoniazid (INH) and rifampicin (RMP) resistance in Mycobacterium tuberculosis complex (MTC) isolates are mainly based on mutations in a limited number of genes. However, mutation frequencies vary in different mycobacterial populations. In this work, we analyzed the distribution of resistance-associated mutations in M. tuberculosis and M. africanum strains from Ghana, West Africa. The distribution of mutations in katG, fabG1-inhA, ahpC, and rpoB was determined by DNA sequencing in 217 INH-resistant (INHr ) and 45 multidrug-resistant (MDR) MTC strains isolated in Ghana from 2001 to 2004. A total of 247 out of 262 strains investigated (94.3%) carried a mutation in katG (72.5%), fabG1-inhA (25.1%), or ahpC (6.5%), respectively. M. tuberculosis strains mainly had katG 315 mutations (80.1%), whereas this proportion was significantly lower in M. africanum West-African 1 (WA1) strains (43.1%; p < 0.05). In contrast, WA1 strains showed more mutations in the fabG1-inhA region (39.2%, p < 0.05) compared to M. tuberculosis strains (20.9%). In 44 of 45 MDR strains (97.8%) mutations in the 81-bp core region of the rpoB gene could be verified. Additionally, DNA sequencing revealed that 5 RMP-susceptible strains also showed mutations in the rpoB hotspot region. In conclusion, although principally the same genes were affected in INHr M. tuberculosis and M. africanum strains, disequilibrium in the distribution of mutations conferring resistance was verified that might influence the efficiency of molecular tests for determination of resistance