Surveillance of antituberculosis drug resistance among children from the Western Cape Province of South Africa--an upward trend.

OBJECTIVES: We assessed the prevalence of antituberculosis drug resistance among children with tuberculosis (TB) in the Western Cape Province of South Africa. METHODS: Drug susceptibility testing for isoniazid and rifampin was prospectively done on all children with culture-confirmed TB at Tygerberg Children's Hospital, Cape Town, from March 2005 through February 2007. Survey results were compared with results from 2 previous surveys. RESULTS: We found 291 children had culture-confirmed TB. Resistance to isoniazid or rifampin increased from 21 of 306 (6.9%) to 41 of 319 (12.9%) and 43 of 285 (15.1%) in the first to third surveys (P = .005) and multidrug resistance from 7 of 306 (2.3%) to 18 of 319 (5.6%) and 19 of 285 (6.7%; P = .033). Although previously treated children had significantly more drug resistance than did new TB cases (19 of 66 [28.8%] vs 24 of 225 [10.7%]; odds ratio = 3.39; 95% confidence interval = 1.62, 7.05), evidence suggests transmission rather than acquisition of resistance. HIV infection was not significantly associated with drug resistance. CONCLUSIONS: Results indicate a high and rising prevalence of anti-TB drug resistance among children in the Western Cape, which suggests ongoing transmission of drug-resistant strains within the community. Improved control of TB in adults, including early identification and treatment of drug-resistant cases, is necessary to reduce transmission to children.

Use of light-emitting diode fluorescence microscopy to detect acid-fast bacilli in sputum.

BACKGROUND: Fluorescence microscopy offers well-described benefits, compared with conventional light microscopy, for the evaluation of sputum smear samples for tuberculosis. However, its use in resource-limited settings has been limited by the high cost of the excitatory light source. We evaluated the diagnostic performance of fluorescence microscopy, using novel light-emitting diode (LED) technology as an alternative to the conventional mercury vapor lamp (MVP). METHODS: Routinely collected sputum specimens from persons suspected to have tuberculosis who attended community clinics were stained with auramine O and were evaluated using 2 different excitatory light sources (MVP and LED); these specimens were then Ziehl-Neelsen stained and reexamined using light microscopy. Two microscopists independently evaluated all smears. Bacterial culture provided the gold standard. RESULTS: Of the 221 sputum specimens evaluated, 36 (16.3%) were positive for Mycobacterium tuberculosis by culture. Sensitivity and specificity documented for the different modalities were 84.7% and 98.9%, respectively, for the LED assessment; 73.6% and 99.8%, respectively, for the MVP assessment; and 61.1% and 98.9%, respectively, for light microscopy. kappa values for interreader variation were 0.87 for the LED assessment, 0.79 for the MVP assessment, and 0.77 for light microscopy. The mean time to read a negative smear was 1.4 min with fluorescence microscopy and 3.6 min with light microscopy, reflecting a time savings of 61% with fluorescence microscopy. CONCLUSION: LED fluorescence microscopy provides a reliable alternative to conventional methods and has many favorable attributes that facilitate improved, decentralized, diagnostic services.

Beijing and Haarlem genotypes are overrepresented among children with drug-resistant tuberculosis in the Western Cape Province of South Africa.

Drug resistance among children with culture-confirmed tuberculosis (TB) provides an accurate measure of transmitted drug resistance within the community. We describe the genotype diversity in children with culture-confirmed TB and investigate the relationship between genotype and drug resistance. A prospective study was conducted from March 2003 through August 2005 at Tygerberg Children's Hospital, in the Western Cape Province of South Africa. All children (<13 years of age) diagnosed with culture-confirmed TB were included. Genotype analysis and phenotypic drug susceptibility testing were performed on the first culture-positive isolate from each patient. Mutation analysis was performed on all drug-resistant isolates. Spoligotyping was successfully performed on isolates from 391/399 (98%) children diagnosed with culture-confirmed TB. Drug susceptibility testing was also performed on 391 isolates; 49 (12.5%) were resistant to isoniazid, and 20 (5.1%) of these were resistant to both isoniazid and rifampin. Beijing was the most common genotype family, identified in 130/391 (33.2%) cases, followed by LAM in 114/391 (29.2%) cases. The presence of both Beijing and Haarlem genotype families was significantly associated with drug resistance (26/49 [53.1%] versus 113/342 [33.0%]; odds ratio, 1.7; 95% confidence interval, 1.0 to 2.9). The high prevalence of Beijing and LAM in children with culture-confirmed TB reflects considerable transmission of these genotype families within the community. The overrepresentation of Beijing and Haarlem genotype families in children with drug-resistant TB demonstrates their contribution to transmitted drug resistance and their potential importance in the emergent drug-resistant TB epidemic.