Sudden Increase in Multidrug Resistant Mycobacterium tuberculosis Strains Investigated in South-Eastern Free State, South Africa

Abstract

Background: During the past decade the tuberculosis (TB) incidence escalated with new cases for the Free State reported as 793/100 000 in 2006 and approximately 60% co-infected with HIV. MDR-TB has risen to 6.9% of previously treated patients and sporadic reports of XDR-TB stress the importance of molecular surveillance and rapid testing. From October 2006 in the Mohokare district there was a sudden alarming rise to 21% of retreatment cases being MDR. The aim of the study was to investigate the possibility of a MDR-TB outbreak in the Mohokare district. Method: Specimens could be collected from 9 of 11 MDRTB patients and one contact in the Mohokare district, Free State. We used a commercially available spoligotyping kit to detect 43 known spacer sequences in the direct repeat (DR) loci of MTB to determine strain similarities and a genotype strip assay for detection of MDR and confirmed results by bidirectional cycle sequencing. Spoligotyping data was entered into an Excel spreadsheet in a binary format and compared to other strains in the world captured in the spolDB3.0 database using SPOTCLUST. Results: 5/9 of the MDR-TB cases were still positive; three of these and an additional contact’s strain was analysed. Spoligotyping suggested that all four strains belonged to different lineages namely LAM9, T1, S and T2. The LAM9 strain had the 526 (GAC3GTC/Asp3Val) rpoB and the 315 (TCG15ACC) katG mutations. The T1 and S strain had the same rpoB 531 (TCG3TTG/Ser3Leu) and 315 (TCG15ACC) katG mutation. The strain from a contact belonged to spoligotype family T2 and was susceptible. Results clearly indicate that the sudden increase in MDR cases is not due to an outbreak. Enormous problems exist in this district with non adherence to treatment, inadequate therapy and absconding of patients from Moroka MDR hospital leading to increased MDR-TB cases. Urgent attention needs to be given to solve this alarming problem.