The level and pattern of anti-tuberculous drug resistance at the Kenyatta national hospital

Abstract

ABSTRACT Background The Kenyatta National Hospital continues to receive an increasing number of patients who have been diagnosed to have tuberculosis (pulmonary and extra pulmonary) as reflected by the number of new daily registrations at the TB clinic and the overall new entries made at the records department from both the inpatients and outpatient clinical departments. Globally the TB pandemic has been compounded by high levels of anti-tuberculous drug resistance including multidrug resistant TB (MDR - TB). In Kenya the level of total drug resistance is still less than 10%. However certain population groups have been found to have a disproportionately higher prevalence of anti-tuberculous drug resistance including pockets of MDR- TB recently reported in Nairobi . Besides , the city of Nairobi is inhabited by different population groups from both within the country and the neighboring countries. The Kenyatta National Hospital serves as a national referral hospital and a primary health care center for the Nairobi residents. Objective: The primary objective was to determine the prevalence of resistance to all the four first line anti-tuberculous drugs and the resistant patterns of the individual drugs as well as to the various combinations of these drugs. The secondary objectives were to determine the demographic and socioeconomic characteristics of those with either of the strains (sensitive or resistant) and the co-morbid factors including HIV infection that may be associated with drug resistance. Study Design: A prospective study that involved culture and drug sensitivity testing of the first line anti-tuberculosis drugs (streptomycin, isoniazid, rifampicin, ethambutol) using , Lowestein Jensten culture media (conventional method) and resistant ratio method to analyze all sputum samples Our study population consisted of patients with pulmonary tuberculosis who attended the tuberculosis outpatient clinic or were admitted to any of the general wards. The diagnosis for tuberculosis was made either by a positive sputum smear microscopy for Ziehl Neelson staining or positive microbiological (culture) method from 1st June 2007 to 30th September 2007 at the Kenyatta National and Referral Hospital, Nairobi Kenya. Results: The following rates of resistance were found in the 81 samples tested: total resistance was 34%, isoniazid mono-resistance was 30%, isoniazid + rifampicin 2.5%,resistance to all the four drugs 2.5%. There was no difference in the demographic and socioeconomic characteristics among those with the resistant and sensitive strains. No difference was found in the HIV status between the two populations (those with the resistant and sensitive strains). Other co-morbid factors associated with the resistant strains were not statistically significant and were considered to be possible incidental associations. Conclusion: These data show higher total drug resistance and isoniazid monoresistance rates than those found at the Kenyatta National Hospital, in previous studies. The trend of MDR-TB has not been well defined. However drug resistance and especially MDR-TB in the context of the high prevalence of HIV in the study population should be closely monitored.