The evolving epidemic of drug-resistant tuberculosis among children in Cape Town, South Africa

Abstract

Tygerberg Children's Hospital, Cape Town, South Africa. To determine the prevalence and trend of drug resistance and human immunodeficiency virus (HIV) co-infection among children with culture-confirmed tuberculosis (TB). Prospective surveillance from March 2007 to February 2009, compared to three previous surveys (1994-1998, 2003-2005, 2005-2007). Drug susceptibility testing (DST) against isoniazid (INH) and rifampicin (RMP) was performed using genotypic and phenotypic testing. If multidrug-resistant TB (MDR-TB) was detected, further DST against ethambutol (EMB) and second-line drugs was performed. A total of 294 children with a median age of 26 months (range 3 days-13 years) were diagnosed with culture-confirmed TB. DST results were available for 292 (99.3%); 41 (14%) were INH-resistant, including 26 (8.9%) with MDR-TB. Four children (1.4%) had RMP monoresistance. EMB resistance was present in 12/24 (50%) MDR-TB cases tested. Two isolates were resistant to ofloxacin; none had extensively drug-resistant TB. Of those tested, 29% (63/217) were HIV-infected. Any resistance to RMP increased between 1994 and 2009 (P < 0.001), as did RMP monoresistance (P = 0.009) and MDR-TB (P < 0.001). Sensitivity was 87.5% and specificity 100% for genotypic compared to phenotypic testing for INH resistance. RMP, and consequently multidrug, resistance is increasing among children with TB in this setting. EMB resistance is common among children with resistance to RMP and INH.