Phenotypic and genotypic analysis of multidrug-resistant tuberculosis in Ethiopia.

SETTING: National Tuberculosis Reference Laboratory, Addis Ababa, Ethiopia. OBJECTIVES: To determine the drug susceptibility pattern of Mycobacterium tuberculosis isolates and to genetically characterise multidrug-resistant tuberculosis (MDR-TB) isolates. DESIGN: A total of 107 M. tuberculosis isolates recovered during the period December 2005-August 2006 were tested for drug susceptibility against streptomycin, isoniazid, rifampicin and ethambutol (SHRE) using the proportion method on Löwenstein-Jensen medium. The MDR-TB isolates were tested against kanamycin, ciprofloxacin, capreomycin, D-cycloserine and ethionamide. Genotyping was performed using spoligotyping. RESULTS: MDR-TB was observed in one of the 44 new cases (2.3%) and 45/63 previously treated patients (71.4%). Drug susceptibility testing against second-line drugs (SLDs) showed that 26.1% of all MDR-TB isolates were susceptible to all SLDs tested and 73.9% were resistant to one or more classes of SLD. Extensively drug-resistant (XDR) TB was detected in two isolates (4.4%). T3_ETH was the predominant spoligotype, followed by CAS_KILI. In this African setting, no Beijing spoligotype was identified. CONCLUSION: Both MDR- and XDR-TB are present in Ethiopian patients. MDR-TB was found to be associated with T3 and Central Asian genotypes.

Status of bovine tuberculosis in Addis Ababa dairy farms.

The study was conducted to determine the status of bovine tuberculosis in Addis Ababa, Ethiopia, by a comparative intradermal tuberculin test of 1,869 animals in 106 farms. Epidemiological information was also collected, taking into account factors chosen for their epidemiological significance and local livestock husbandry characteristics. In addition, milk samples were collected from tuberculin reactors for mycobacterial isolation and characterisation. Chi-square statistic, simple regression and multiple stepwise logistic regression were used to analyse the data. Of the 106 farms examined, 46 (95% confidence interval [CI]: 33.8% to 53.4%) contained comparative skin test reactors. Of the 1,869 animals, 443 (95% CI: 21.8% to 25.7%) were comparative skin test reactors. Furthermore, about 8.5% of tuberculin sensitive cows (12 of a sample of 141) secreted acid-fast bacteria in their milk. The microbes are described in more detail in the paper. Factors identified as possibly increasing the risk of bovine tuberculosis in Addis Ababa were herd size (large herd), farming (housing) condition (poor), and age (older animals). Similarly, as body condition scores improved from poor to medium and then to good, the likelihood of positive results significantly decreased (OR = 0.54; p < 0.01). Other factors including breed, sex, and physiological status of animals did not seem to significantly contribute to tuberculin sensitivity. The finding that large-size and intensively (often poorly) managed herds were at greater risk of bovine tuberculosis suggests that the significance of bovine tuberculosis is increasing in Addis Ababa parallel to an increasing dairy operation. If measures are not taken promptly, the impact on the economy and public health could be enormous.

Drug susceptibility of Mycobacterium tuberculosis in HIV-infected and -uninfected Ethiopians and its impact on outcome after 24 months of follow-up.

From a prospective cohort study on tuberculosis/human immunodeficiency virus (TB/HIV) interaction in Addis Ababa, Ethiopia, drug susceptibility results were available for 94 TB patients (46% HIV-infected). Resistance to one or more drug(s) was detected in 21 (22.3%) and multidrug resistance in five (5.3%) patients. Occurrence of resistance was not related to HIV status or outcome after 24 months of follow-up. However, among HIV-infected TB patients who died during follow-up, survival time in those with a resistant Mycobacterium tuberculosis strain was significantly shorter compared to those with a sensitive strain (6 vs. 13 months). Early detection of drug resistance and timely treatment change can therefore have a positive impact on survival in HIV-infected TB patients.

Tuberculous lesions not detected by routine abattoir inspection: the experience of the Hossana municipal abattoir, southern Ethiopia.

The efficacy of the meat inspection procedures implemented for the detection of tuberculous cattle was evaluated by testing for bovine tuberculosis in 751 animals. The study involved routine inspection at slaughter, collection of tissues for detailed examination in the laboratory, and bacteriological investigation to identify Mycobacterium bovis. Of the 751 carcasses examined, 34 (4.5%) were found to have tuberculous lesions. Routine abattoir inspection detected only 29.4% of the carcasses with visible lesions. Eighty-four percent of the tuberculous lesions were found in the lungs and thoracic lymph nodes, 11.5% in the lymph nodes of the head, and the remaining 4.5% in the mesenteric and other lymph nodes of the carcasses. In addition, M. bovis was isolated from a carcass that presented no gross tuberculosis lesions. The low sensitivity of routine abattoir inspection demonstrates that existing necropsy procedures should be improved.

Sensitivity to anti-tuberculosis drugs in HIV-positive and -negative patients in Addis Ababa.

A cross-sectional survey was conducted between 1 August and 31 December, 1998 in Addis Ababa, Ethiopia to determine the rate of primary drug resistance to anti-tuberculosis drugs and to investigate its possible association with HIV infection. Sputum culture, sensitivity to first-line anti-tuberculosis drugs and HIV testing were done for 236 sputum smear-positive pulmonary tuberculosis patients. Primary drug resistance level (single or multidrug resistance) had not changed significantly since 1994. Primary resistance occurred more often among HIV-positive than among HIV-negative patients. The association between drug resistance and HIV will have a serious impact in the control of tuberculosis because in recent years the prevalence of HIV has increased dramatically in Ethiopia. Therefore, further studies on drug resistance and HIV infection and the establishment of drug resistance surveillance are recommended.

Primary resistance to anti-tuberculosis drugs in Addis Ababa, Ethiopia.

OBJECTIVE: To obtain current, representative information on current drug resistance patterns in Addis Ababa, Ethiopia. DESIGN: A cross-sectional study whereby 167 isolates were tested for susceptibility to the anti-tuberculosis drugs commonly used in the country (isoniazid, thiacetazone, rifampicin, streptomycin and ethambutol). All hospitals, health centres and 6 of the 9 clinics in Addis Ababa were included in the study. RESULT: Overall primary drug resistance was found to be 15.6% (26/167). Primary resistance to two or more drugs was 7.2% (12/167). The highest rate of primary resistance was to streptomycin (10.2%) followed by isoniazid (8.4%). Resistance to rifampicin was low (1.8%, 3/167) and to ethambutol nil. Multiple drug resistance in combinations with rifampicin was low. CONCLUSION: To prevent further development and spread of resistance, universal use of standard treatment protocol, control of the circulation of anti-tuberculosis drugs, training of health workers, expansion of strictly supervised short-course treatment and establishing a nation-wide and regular surveillance system are recommended.