Mycobacterium africanum Subtype II Is Associated with Two Distinct Genotypes and Is a Major Cause of Human Tuberculosis in Kampala, Uganda

University of Arkansas at Little Rock, Little Rock, Arkansas, United States
Journal of Clinical Microbiology (Impact Factor: 3.99). 10/2002; 40(9):3398-405. DOI: 10.1128/JCM.40.9.3398-3405.2002
Source: PubMed


The population structure of 234 Mycobacterium tuberculosis complex strains obtained during 1995 and 1997 from tuberculosis patients living in Kampala, Uganda (East Africa), was analyzed
by routine laboratory procedures, spoligotyping, and IS6110 restriction fragment length polymorphism (RFLP) typing. According to biochemical test results, 157 isolates (67%) were classified
as M. africanum subtype II (resistant to thiophen-2-carboxylic acid hydrazide), 76 isolates (32%) were classified as M. tuberculosis, and 1 isolate was classified as classical M. bovis. Spoligotyping did not lead to clear differentiation of M. tuberculosis and M. africanum, but all M. africanum subtype II isolates lacked spacers 33 to 36, differentiating them from M. africanum subtype I. Moreover, spoligotyping was not sufficient for differentiation of isolates on the strain level, since 193 (82%)
were grouped into clusters. In contrast, in the IS6110-based dendrogram, M. africanum strains were clustered into two closely related strain families (Uganda I and II) and clearly separated from the M. tuberculosis isolates. A further characteristic of both M. africanum subtype II families was the absence of spoligotype spacer 40. All strains of family I also lacked spacer 43. The clustering
rate obtained by the combination of spoligotyping and RFLP IS6110 analysis was similar for M. africanum and M. tuberculosis, as 46% and 49% of the respective isolates were grouped into clusters. The results presented demonstrate that M. africanum subtype II isolates from Kampala, Uganda, belong to two closely related genotypes, which may represent unique phylogenetic
branches within the M. tuberculosis complex. We conclude that M. africanum subtype II is the main cause of human tuberculosis in Kampala, Uganda.

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    • "All Mtb complex strains were analyzed by spoligotyping using standard protocols[26](reagents from Ocimum Biosolution) and assigned specific spoligotype nomenclature (SIT) according to the SITVITWEB database[27]. The Uganda genotype is characterized by a spoligotype pattern lacking spacers 40, or both 40 and 43 as previously described[28]. Region of difference (RD) analysis All isolates were analyzed for a deletion at the RD724 locus, which is specific for the Uganda genotype as previously described[5]. "
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    ABSTRACT: Background: Mycobacterium tuberculosis (Mtb) is reported to infect about a third of the world's population but only 10 % are thought to develop active tuberculosis (TB) disease. Host immunity regulated by human leukocyte antigens (HLA) is an important determinant of the outcome of the disease. Here we investigate HLA class II gene polymorphisms in susceptibility to TB, and whether particular HLA class II alleles were associated with TB in Uganda. Methods: HIV negative patients with pulmonary TB (n = 43) and genetically related healthy household controls (n = 42) were typed for their HLA II class alleles using polymerase chain reaction sequence specific primer amplification. Results: The HLA-DQB1*03:03 allele was significantly less frequent in patients compared to healthy controls (10 % in controls versus 0 % in patients, p = 0.003). After correction for multiple comparisons the difference remained significant (p = 0.018). Conclusions: Our results suggest that the HLA-DQB1*03:03 allele may be associated with resistance to TB.
    Preview · Article · Dec 2015 · BMC Infectious Diseases
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    • "The T2 lineage, to which the Uganda genotype belongs was identified. T2 lineage strains are characterized by a spoligotype pattern lacking spacers 40, or both 40 and 43 as previously described [34]. "
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    ABSTRACT: Tuberculous lymphadenitis is next to pulmonary tuberculosis as the most common cause of tuberculosis. Uganda genotype, one of the sub-lineages of Mycobacterium tuberculosis, is the most prevalent cause of pulmonary tuberculosis in Uganda. We here investigate the clinicopathological characteristics of patients with tuberculous lymphadenitis infected with M. tuberculosis Uganda genotype compared with those infected with M. tuberculosis non-Uganda genotype strains. Between 2010 and 2012, we enrolled 121 patients (mean age 28.5 yrs, male 48%; female 52%) with tuberculous lymphadenitis, and categorized them by their M. tuberculosis genotypes. The clinical features and lymph node cytopathological parameters were compared between patients in the Uganda and non-Uganda categories using a crude and multivariable logistic regression model with adjustment for confounding factors. Of the 121participants, 56 (46%) were infected with strains of Uganda genotype. Patients infected with this genotype had significantly lower frequency of abdominal lymphadenopathy (odds ratio 0.4, p = 0.046) after adjusting for sex, age and HIV. Abdominal lymphadenopathy was also significantly associated with abnormal chest X-ray (p = 0.027). Tuberculous lymphadenitis patients infected with M. tuberculosis Uganda genotype were significantly less prone to have abdominal lymphadenopathy indicating potential reduced ability to disseminate and supporting the concept that differences in M. tuberculosis genotype may have clinical implications.
    Full-text · Article · Apr 2014 · BMC Clinical Pathology
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    • "Recent studies in Uganda indicated that the majority of TB cases are due to the MTBC Uganda family (L4-U) [7,8], a sub-lineage of Lineage 4 defined by a deletion in the Region of Difference (RD) 724, the spoligotype finger print (33–36, 40 and 43 spacers missing), and several SNPs [1,9,10]. Although earlier studies had defined this L4-U family as Mycobacterium africanum sub-type II based on colony morphology and biochemical tests [11,12], advances in molecular classification have led to its reclassification as M. tuberculosis sensu stricto [13]. "
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    ABSTRACT: Previous studies have shown that Mycobacterium tuberculosis (MTB) Uganda family, a sub-lineage of the MTB Lineage 4, is the main cause of tuberculosis (TB) in Uganda. Using a well characterized patient population, this study sought to determine whether there are clinical and patient characteristics associated with the success of the MTB Uganda family in Kampala. A total of 1,746 MTB clinical isolates collected from1992-2009 in a household contact study were genotyped. Genotyping was performed using Single Nucleotide Polymorphic (SNP) markers specific for the MTB Uganda family, other Lineage 4 strains, and Lineage 3, respectively. Out of 1,746 isolates, 1,213 were from patients with detailed clinical data. These data were used to seek associations between MTB lineage/sub-lineage and patient phenotypes. Three MTB lineages were found to dominate the MTB population in Kampala during the last two decades. Overall, MTB Uganda accounted for 63% (1,092/1,746) of all cases, followed by other Lineage 4 strains accounting for 22% (394/1,746), and Lineage 3 for 11% (187/1,746) of cases, respectively. Seventy-three (4 %) strains remained unclassified. Our longitudinal data showed that MTB Uganda family occurred at the highest frequency during the whole study period, followed by other Lineage 4 strains and Lineage 3. To explore whether the long-term success of MTB Uganda family was due to increased virulence, we used cavitary disease as a proxy, as this form of TB is the most transmissible. Multivariate analysis revealed that even though cavitary disease was associated with known risk factors such as smoking (adjusted odds ratio (aOR) 4.8, 95% confidence interval (CI) 3.33-6.84) and low income (aOR 2.1, 95% CI 1.47-3.01), no association was found between MTB lineage and cavitary TB. The MTB Uganda family has been dominating in Kampala for the last 18 years, but this long-term success is not due to increased virulence as defined by cavitary disease.
    Full-text · Article · Oct 2013 · BMC Infectious Diseases
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