Reccurence of tuberculosis and its association with emergence of multidrug resistance strain of mycobacteria in Nairobi,Kenya 2010 to 2012co

Abstract

The resurgence of tuberculosis (TB) has been associated mainly with Human Immuno deficiency Virus (HIV) and widespread poverty. The HIV pandemic and emergence of resistant strains of Mycobacterium tuberculosis threatens the success of patient treatment and TB control programs. The initial treatment of TB involves the administration of four

drugs namely;

isoniazid, rifampicin, pyrazinamide and either ethambutol or

streptomycin. Isoniazid and rifampicin are critical in successfull treatment of TB. Resistance to any anti-TB drugs can develop spontaneously as a result of mutation then there after under selective pressure. Few epidemiological studies done in Nairobi have shown the presence of multidrug resistant TB (MDR TB) but none has determined the distribution of these cases and their potential causes. There is also limited information on the exact prevalence of resistance to anti-tuberculosis drugs in high density populations with high rates of tuberculosis and HIV co-infection such as those in Nairobi where there is great potential for spread. The objective of this study was to determine the magnitude, strain patterns and and identification risk factors associated with the resistance. This was a cross sectional study. Study sites were selected from each of the 8 districts in Nairobi and study subjects selected using weighted cluster sampling based on the patient population proportions of new smear positive cases notified in 2007. Eligible patients were enrolled in the study consecutively after consenting until the number allocated to each study site was achieved. Sputum samples were collected from patients before start of treatment in accordance with standard programme procedures XVI

Image and transported to the central reference laboratory (CRL) where they were processed for culture and drug susceptability testing (DST) using the standard procedures. All culture isolates positive for Mycobacterium tuberculosis (MTB) were tested for susceptibility to first line anti-tuberculosis drugs namely; isoniazid, streptomycin; rifampicin and ethambutol using the conventional Mycobacterium Growth Indicator Tube (MGIT) medium. Spoligotying molecular method was used to identify isolates with strain families. Data was analysed using the SPSS software version 17. The standard chi-square test and Fishers exact test were used to compare 2 data points and a p-value of less than 0.05 was considered significant. The Mantel-Hansen test was used for odds ratios. A total of 691 TB patients were enrolled for study with mean age of 31.3 and median of 30 years. Among the patients, 438 (63.4%) were new smear positive TB cases from whom 368 Mycobacterium tuberculosis isolates were subjected to drug susceptiblity testing (DST) and 253 (36.6%) were previously treated smear positive TB cases from whom 199 MTB isolates were subjected to DST. Eeighty five percent and seventy seven percent of the MTB isolates from new patients and previously treated patients, respectively, were fully sensitive to all the drugs tested. Initial resistance (i.e. resistance among new patients) to isoniazid, streptomycin, ethambutol and rifampicin was 10.3%, 4.3%, 5.1 % and 0.81 %, respectively. Among previously treated patients resistance to isoniazid, streptomycin, ethambutol and rifampicin was 18.1 %, 10.5%, 7.03% and 9.04%, respectively. The prevalence of MDR TB was 0.54% and 8.54% among new and previously treated patients respectively. No Extensive drug resistant TB (XDR TB) was identified in this population. The study found out that the TB disease in