Drug-resistant tuberculosis in children less than 5 years old with culture positive mycobacterium tuberculosis

Abstract

Background: Diagnosis of paediatric tuberculosis remains a challenge due to the difficulty in obtaining samples from children and the low sensitivity of culture confirmation. Drug resistance in TB continues to be a significant challenge in South Africa. Microbiologic confirmation of tuberculosis in children is necessary to exclude drug-resistant tuberculosis in face of the high multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) rates reported in the adult population. We describe the rates of drug-resistant TB in children less than 5 years old from KwaZulu Natal – a province in South Africa with the highest burden of both TB and HIV disease. Methods & Materials: A retrospective descriptive analysis was done of specimens from children less than 5 years old submitted to TB reference laboratory in KwaZulu-Natal, South Africa. Data was collected from 2012 to 2014. Specimens cultured included respiratory samples, lymph node aspirates, pleural and peritoneal fluid, cerebrospinal fluid, bone and tissue samples. Cultures were performed using the automated Mycobacterial Growth Indicator Tube 960 system (Becton Dickinson) and identification and susceptibility was confirmed with the line probe MTBDR plus assay (Hain-Life Science). From 2012 the Xpert MTB/RIF was introduced into the diagnostic algorithm for MTB detection and Rifampicin resistance. Results: 903 children were found to have culture-confirmed TB during this 3 year period. Drug susceptibility testing showed susceptible MTB ranging from 71-82% in the various age groups. Overall the resistance to isoniazid and rifampicin (MDR) rates ranged from 11-16% with the highest rates found in 2 year old age group. Extensively drug-resistant TB (0-2.1%) was present in all age groups. INH mono-resistance was 3,4% and Rifampicin mono-resistance was 2.8%. Conclusion: High rates of Mycobacterium tuberculosis including extensively drug resistant TB were found in children less than one, which indicates the burden of TB infection among woman during childbearing years. INH mono-resistance is of concern as this will not be detected by the current diagnostic algorithm that includes the Xpert MTB/RIF for MTB detection and Rifampicin resistance. Children with INH mono-resistance may benefit from high-dose isoniazid therefore bacteriological confirmation through culture is important in management of childhood TB.