摘要：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. Drug-resistant tuberculosis (TB), and more so multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB, pose a major threat to TB control programs. 1 Recent reports of extensively drug-resistant TB and associated mortality emphasize the importance of continued surveillance and the need for measures to prevent development and spread of drug-resistant TB. 2 , 3 In most developing countries, the diagnosis of adult TB is by sputum smear microscopy. Culture and drug susceptibility testing are not routinely done, 4 , 5 which precludes ongoing surveillance of drug-resistance patterns within the community. A further challenge is the difficulty of accurate categorization of drug resistance. Recently, the previous classification of primary and acquired drug resistance has been replaced by more pragmatic definitions: new drug resistance (i.e., resistance in cultures from patients who received no previous TB treatment, or treatment for less than 1 month) and previously treated drug resistance (i.e., resistance in cultures from patients previously treated for 1 month or more). 4 Nonetheless, uncertainty remains regarding classification of drug resistance. From a TB control perspective, it is imperative to distinguish between primary (i.e., transmitted) drug resistance and acquired (i.e., developed) drug resistance. New drug resistance implies poor control over transmission of disease, whereas development of drug resistance in a patient usually implies poor management of disease. Children with culture-confirmed TB provide an accurate measure of transmitted drug resistance because even children who have received previous treatment for TB tend to have transmitted rather than acquired drug resistance. 1 This is mainly because of the paucibacillary nature of childhood TB, implying a low risk of developing random drug resistance on treatment. Therefore, surveillance of drug resistance patterns among children with culture-confirmed TB provides an accurate measure of transmitted drug resistance within a community. 6 The prevalence of drug-resistant TB provides an indication of how well TB-control programs are functioning. In particular, trends in new (transmitted) drug resistance, such as is most often found among children, reflect the ability of TB-control programs to limit the spread of resistant organisms within communities and can serve as a sentinel surveillance system. 1 , 7 We report on trends in the prevalence of drug resistance among children with culture-confirmed TB during 3 surveillance periods at a major referral hospital in South Africa.
