Identification of MDR-TB Beijing/W and other Mycobacterium tuberculosis genotypes in Nairobi, Kenya.

SETTING: Suspected tuberculosis (TB) patients in Nairobi, Kenya. OBJECTIVE: To identify the presence of multidrug-resistant (MDR) Beijing/W type and other genotypes of Mycobacterium tuberculosis. METHODS: Thirty-three isolates resistant to one or more drugs (resistance ratio method), including 15 MDR isolates and 40 susceptible isolates selected at random, were analysed by dot-blot hybridisation for mutations associated with resistance to isoniazid, rifampicin, streptomycin and ethambutol. All strains were genotypically classified using spoligotyping. RESULTS: Of the 33 drug-resistant isolates, 21 (64%) were from males and 12 (36%) were from females. Mutations associated with resistance to isoniazid (katG 315) and rifampicin (rpoB526, 531) were confirmed in 83.3% and 100% of the isolates, respectively, and in 87% of the MDR isolates. Mutations were detected in 25% and 71.5% of the isolates resistant to streptomycin (rpsL43) and ethambutol (embB306), respectively. No mutations were detected in drug-susceptible isolates. Spoligotyping grouped the isolates into 25 groups. Ten of these groups corresponded to previously identified strain groups, including seven families in the international database. One of these families (CAS1) comprised six (40%) of the 15 MDR isolates. Another family (Beijing) had six (8.3%) isolates, of which two (33.3%) were MDR (Beijing/W). CONCLUSION: This study is the first in Kenya and the second in sub-Saharan Africa to report the presence of MDR Beijing/W type and other possible drug-resistant outbreak strains. Application of the molecular techniques and markers will allow us to monitor the spread of existing drug-resistant strains and the appearance of new ones.

Use of common reagent containers to stain sputum smears for acid fast bacilli using ziehl-neelsen technque

The use of common reagent containers for mass staining of sputum smears for acid fast bacilli (AFB) by the Ziehl-Neelsen (ZN:) Technique has previously been discouraged for fear of cross contamination. We undertook the present study to ascertain whether this fear has any justification. Out of 1296 smears prepared from 198 specimens including 9 known negative controls; 108 stainings were performed. 70 specimens and all positive controls were repeatedly positive on different stainings. 69 (99) cases and all positive controls were confirmed by culture. No carry over of AFB from positive to negative smears was experienced. Time; cost and staining mess was significantly reduced during mass eestaining. The use of a common container for staining of sputum smears for AFB by the ZN technique is not only economical but also ideal for laboratories where space is insufficient and larg numbers of sputum specimens are involved