Molecular characterisation of Mycobacterium bovis isolates from cattle carcases at a city slaughterhouse in Uganda.

During a period of eight months, the carcases of 16,800 slaughter cattle were inspected at a city abattoir in Uganda. Eighty-seven of them had tuberculosis-like lesions and tissue samples were cultured. Only 17 cultures yielded acid-fast bacilli; 11 of them were confirmed as Mycobacterium bovis and six as non-tuberculous mycobacteria (NTM). GenoType Mycobacterium assays on the six NTM identified two as Mycobacterium fortuitum and one as Mycobacterium intracellulare, but three were unidentified. Characterisation of the M bovis isolates by spoligotyping and IS6110 restriction fragment length polymorphism (RFLP) revealed that five of the six spoligotype patterns observed in the 11 strains had not been previously reported, and seven of the nine isolates typed by RFLP had multicopy number IS6110 patterns. Six of the 11 infected carcases had multiple sites of infection, but none was condemned as unfit for human consumption.

Mycobacterium tuberculosis Uganda genotype is the predominant cause of TB in Kampala, Uganda.

SETTING: Rubaga Division, Kampala, Uganda. OBJECTIVE: To use polymerase chain reaction (PCR) based regions of difference (RD) analysis to study the species diversity of Mycobacterium tuberculosis complex isolates from a community-based sample of tuberculosis (TB) patients from Rubaga and to perform long sequence polymorphism (LSP) analysis to further characterise the M. tuberculosis Uganda genotype, a group of strains previously recognised by their characteristic spoligotype patterns. DESIGN: For the present study, 344 consecutive TB patients attending clinics in Rubaga Division were enrolled. Sample processing and culture were performed at the National Tuberculosis and Reference Laboratory and molecular assays at Makerere Medical School. Species identification was achieved by determining the RDs, while spoligotyping and LSP analysis were performed to characterise the M. tuberculosis Uganda genotype. RESULTS: Of the 344 isolates, 343 (99.7%) were M. tuberculosis sensu stricto, while one was classical M. bovis. The Uganda genotype strains characteristically lacked RD724, a locus that defines one of the major sub-lineages of M. tuberculosis, which suggested that this geographically constrained lineage is specifically adapted to a central African human host population. CONCLUSION: M. tuberculosis is the most prevalent species of the M. tuberculosis complex in Kampala, and the Uganda genotype is the predominant strain.

Extensive transmission of an isoniazid-resistant strain of Mycobacterium tuberculosis in Sweden.

SETTING: City of Stockholm, Sweden. BACKGROUND: The incidence of tuberculosis (TB) in Sweden increased by 40% between 2003 and 2005. The spread of a unique TB strain resistant to isoniazid (INH) contributed to this increase. OBJECTIVE: To describe outbreaks of TB caused by this single strain, elucidate possible causes for its extensive spread and identify shortcomings of the TB control programme in Sweden. RESULTS: We identified a cluster consisting of 102 culture-confirmed TB cases with identical DNA fingerprints and 26 epidemiologically related cases, not confirmed by culture, all diagnosed between 1996 and 2005. Five partly separate outbreaks of this strain were discovered. Epidemiological links were established for 56% of the culture-confirmed cases and for all cases not confirmed by culture. Three patients died while receiving treatment, four became failures and eight defaulted or were lost to follow-up. Only eight patients received directly observed treatment (DOT) up to a period of 3 months, although 40% had poor adherence. CONCLUSIONS: Shortcomings of the national TB programme were revealed. Improved contact tracing and case holding, including DOT, is crucial to reduce TB transmission in Sweden.

Outbreak of Mycobacterium tuberculosis infection among captive Asian elephants in a Swedish zoo.

Between 2001 and 2003, there was an outbreak of tuberculosis in a Swedish zoo which involved elephants, giraffes, rhinoceroses and buffaloes. Cultures of trunk lavages were used to detect infected elephants, tuberculin testing was used in the giraffes and buffaloes, and tracheal lavage and tuberculin testing were used in the rhinoceroses. The bacteria isolated were investigated by spoligotyping and restriction fragment length polymorphism. Five elephants and one giraffe were found to have been infected by four different strains of Mycobacterium tuberculosis.

Spread of drug-resistant pulmonary tuberculosis in Estonia.

Restriction fragment length polymorphism (RFLP) analysis of 209 Mycobacterium tuberculosis clinical isolates obtained from newly detected pulmonary tuberculosis patients (151 male and 58 female; mean age, 41 years) in Estonia during 1994 showed that 61 isolates (29%) belonged to a genetically closely related group of isolates, family A, with a predominant IS6110 banding pattern. These strains shared the majority of their IS6110 DNA-containing restriction fragments, representing a predominant banding pattern (similarity, >65%). This family A comprised 12 clusters of identical isolates, and the largest cluster comprised 10 strains. The majority (87.5%) of all multidrug-resistant (MDR) isolates, 67.2% of all isolates with any drug resistance, but only 12% of the fully susceptible isolates of M. tuberculosis belonged to family A. These strains were confirmed by spoligotyping as members of the Beijing genotype family. The spread of Beijing genotype MDR M. tuberculosis strains was also frequently seen in 1997 to 1999. The members of this homogenous group of drug-resistant M. tuberculosis strains have contributed substantially to the continual emergence of drug-resistant tuberculosis all over Estonia.

Evolution and clonal traits of Mycobacterium tuberculosis complex in Guinea-Bissau.

Two hundred twenty-nine consecutive isolates of Mycobacterium tuberculosis complex from patients with pulmonary tuberculosis in Guinea-Bissau, which is located in West Africa, were analyzed for clonal origin by biochemical typing and DNA fingerprinting. By using four biochemical tests (resistance to thiophene-2-carboxylic acid hydrazide, niacin production, nitrate reductase test, and pyrazinamidase test), the isolates could be assigned to five different biovars. The characteristics of four strains conformed fully with the biochemical criteria for M. bovis, while those of 85 isolates agreed with the biochemical criteria for M. tuberculosis. The remaining 140 isolates could be allocated into one of three biovars (biovars 2 to 4) representing a spectrum between the classical bovine (biovar 1) and human (biovar 5) tubercle bacilli. By using two genotyping methods, restriction fragment length polymorphism analysis with IS6110 (IS6110 RFLP analysis) and spoligotyping, the isolates could be separated into three groups (groups A to C) of the M. tuberculosis complex. Group A (n = 95), which contained the majority of classical human M. tuberculosis isolates, had large numbers of copies of IS6110 elements (mean number of copies, 9) and a distinctive spoligotyping pattern that lacked spacers 33 to 36. Isolates of the major group, group B (n = 119), had fewer IS6110 copies (mean copy number, 5) and a spoligotyping pattern that lacked spacers 7 to 9 and 39 and mainly comprised isolates of biovars 1 to 4. Group C isolates (n = 15) had one to three IS6110 copies, had a spoligotyping pattern that lacked spacers 29 to 34, and represented biovar 3 to 5 isolates. Four isolates whose biochemical characteristics conformed with those of M. bovis clustered with the group B isolates and had spoligotype patterns that differed from those previously reported for M. bovis, in that they possessed spacers 40 to 43. Interestingly, isolates of group B and, to a certain extent, also isolates of group C showed a high degree of variability in biochemical traits, despite genotypic identity in terms of IS6110 RFLP and spoligotype patterns. We hypothesize that isolates of groups B and C have their evolutionary origin in West Africa, while group A isolates are of European descent.

Antimycobacterial synergism of clarithromycin and rifabutin.

Clarithromycin and rifabutin are among the most promising drugs for the therapy of infections caused by Mycobacterium avium or other atypical mycobacteria. Since synergism of combined drugs is important in order to achieve strong antimycobacterial activity, the combined inhibitory effects of antibacterial agents should also be investigated when agents are evaluated for possible use in antimycobacterial drug therapy. In the present study we examined the antimycobacterial activity of clarithromycin, rifabutin, and their combination against 51 clinical isolates of the M. avium complex from patients with acquired immune deficiency syndrome (AIDS) with disseminated mycobacteriosis. A concentration-dependent inhibition was seen for each drug. The antibacterial effect was significantly more pronounced for the combined drugs than for the agents tested separately. Synergism, against up to 88% of the strains tested, was seen for the tested drugs combined at different concentrations. All 51 M. avium strains were susceptible to the combination of 4 mg/l clarithromycin and 2 mg/l rifabutin.

Biochemical heterogeneity of Mycobacterium tuberculosis complex isolates in Guinea-Bissau.

Fifty-six strains of the Mycobacterium tuberculosis complex from patients in Guinea-Bissau were examined by using four biochemical tests (niacin production, nitrate reductase, pyrazinamidase, and resistance to thiophen-2-carboxylic acid hydrazide). The isolates were divided into five different biovars within a spectrum ranging from classical human M. tuberculosis to classical M. bovis.