Anti-tuberculosis drug resistance in Nairobi, Kenya

Background: Drug resistant tuberculosis (TB) which is a state when Mycobaterium tuberculosis (MTB) organisms are resistant to antimicrobial agents at the levels attainable in blood and tissue pose a serious threat to TB control programs. Limited information exists on the exact prevalence of resistance to anti-tuberculosis drugs in populations with high rates of tuberculosis and HIV co-infection such as those in Nairobi, Kenya. Setting: A cross sectional study was conducted among new and previously treated consecutive sputum smear positive pulmonary tuberculosis (PTB) patients of 14 years and older at 16 diagnostic and treatment facilities in Nairobi, Kenya, between February and August 2010. Objective: To determine the magnitude of drug resistance to first line antituberculosis drugs among MTB isolates obtained from a study addressing the diagnosis and epidemiology of drug resistant tuberculosis in Nairobi, Kenya. Methods: Sputum samples from patients with bacteriologically confirmed PTB on microscopy were cultured on Lowenstein Jensen (LJ) media. Participants were offered diagnostic testing and counselling for HIV testing. Strains of MTB complex from Lowenstein Jensen (LJ) slopes were subjected to drug susceptibility testing (DST) to isoniazid (H), rifampicin (R), streptomycin (S), and ethambutol (E) using the proportional method on the Mycobacterium Growth Indicator Tube (MGIT) conventional method. Results: A total of 595 TB patients had their MTB strains DST done. Of the 568 (95.4%) patients who had valid results for analysis, 369 were new and 199 previously treated. About eighty five percent and seventy seven percent of the strains from new patients and previously treated patients were fully sensitive to all the drugs tested respectively. Any resistance to isoniazid, streptomycin, ethambutol and rifampicin was 10.3%, 4.3%, 5.1% and 0.81% respectively among new patients. Among previously treated patients any resistance to isoniazid, streptomycin, ethambutol and rifampicin was 18.1%, 10.5%, 7.03% and 9.04% respectively. The prevalence of MDR TB defined as resistant to at least both isoniazid and rifampicin was 0.54% and 8.54% among new and previously treated patients respectively. Conclusion: The study found high levels of drug resistant TB in Nairobi compared to other previous studies done in the country. MDR TB in Kenya is now a reality and the situation in Nairobi being the largest cosmopolitant city is worrying. The upword trend of MDR TB in Nairobi is course of concern. This calls for urgent concerted efforts to address the problem especially the strenghthening of the implementation of the comprehensive framework of the DOTS-Plus strategy for appropriate management of MDR-TB

Diversity of Mycobacterium tuberculosis strains in Nairobi, Kenya

Setting: Tuberculosis (TB) patients attending 16 public health facilities in Nairobi, Kenya. Objective: To determine the Mycobacterium tuberculosis (M.tuberculosis) strain families circulating in Nairobi, Kenya. Methods: Sputum specimens from consecutive new and previously treated smear positive pulmonary TB patients were collected between February and August 2010 and cultured on Lowenstein9Jensen media. Spoligotyping was done on DNA extracted from the first isolate of each patient. The international spoligotype data base (SpolDB4) was used to group isolates into strain families. Results: Fourty seven different strain families were identified from 536 isolates. The principal groups were; CAS1_KILI 96/536 (17%), T1 69/536 (12%), Beijing 65/536 (12%), LAM9 46/536 (9% ), LAM3 & S/Conversant 37/536 (7% ), LAM11_ZWE 26/536 (5%), CAS1_DELHI 24/536 (4%) and T2 24/536 (4%). Others identified and are found in the SpolDB4 were 113/536 (21%). A possible new M.tuberculosis strain family was identified with 21/536 (4%) isolates which was designated as Nairobi subtype. Others identified not previously included in the SpolDB4 accounted for 15/536 (3%). Conclusion: We found a diverse array of M.tuberculosis strain families which could be indicative of a cosmopolitant polulation with frequent migration that may suggest that the dorminant strain families may have been present in the population for an extended period of time or on going transmision of closely related strains families. The emergence of the Beijing strains poses a serious threat to TB control due to its high virulence and frequent association with multidrug resistance. We therefore call for strenghthening efforts on early case finding through enhanced public health education campains and provision of accessible diagnostic services with enhanced treatment compliance