Spatial Heterogeneity of Extensively Drug Resistant-Tuberculosis in Western Cape Province, South Africa

Tuberculosis (TB) remains a leading global infectious disease killer. Treatment outcomes are especially poor among people with extensively drug-resistant (XDR) TB, until recently defined as rifampicin-resistant (RR) TB with resistance to an aminoglycoside and a fluoroquinolone, with efforts urgently needed to improve response. We used laboratory TB test results from Western Cape province, South Africa between 2012 and 2015 to identify XDR-TB and pre-XDR-TB (RR-TB with resistance to one second-line drug) spatial hotspots. We mapped the percentage and count of individuals with RR-TB that had XDR-TB and pre-XDR-TB across the province and in Cape Town, as well as amikacin-resistant and ofloxacin-resistant TB. We found the percentage of pre-XDR-TB and the count of XDR-TB/pre-XDR-TB highly heterogeneous with clear geographic hotspots within RR-TB high burden areas. We also found hotspots in both percentage and count of amikacin-resistant and ofloxacin-resistant TB. The spatial distribution of percentage ofloxacin-resistant TB hotspots is similar to XDR-TB hotspots, suggesting that fluoroquinolone-resistace is often the first step to additional resistance. Our work shows that interventions used to reduce XDR-TB incidence and improve outcomes may need to be targeted within spatial locations with RR-TB. Further research is required to understand underlying drivers of XDR-TB transmission in these locations.