Biocidal effect of bleach on Mycobacterium tuberculosis: a safety measure.

BACKGROUND: Although treatment of sputum using bleach has shown increased sensitivity in smear microscopy, the safety aspect of sodium hypochlorite (NaOCl) has not been addressed. OBJECTIVE: To determine the biocidal effect of NaOCl on Mycobacterium tuberculosis when used as a safety measure in direct sputum smear microscopy for the diagnosis of tuberculosis (TB). METHOD: A total of 156 smear- and culture-positive pooled sputum specimens were assessed for the viability of M. tuberculosis after treatment with NaOCl. Each specimen was divided into 11 equal portions. One portion was directly cultured. Each of five portions was treated with 3.5% NaOCl and the other five with 5% NaOCl. Specimens were then cultured at intervals of 15 min and 1, 3, 15 and 24 h. RESULTS: A total of 18 (11.5%) specimens showed growth after treatment with NaOCl. Of these, 5 (3.2%) showed growth upon treatment with 3.5% NaOCl at 15 min and 15 and 24 h. Ten (6.4%) showed growth after treatment with 5% NaOCl between 15 min and 3 h, but none showed growth after 15 h. Three (1.9%) specimens showed growth in both concentrations. CONCLUSION: Our preliminary findings show that exposure of sputum to 5% NaOCl for at least 15 h may be a safety procedure in smear microscopy for the diagnosis of TB. However, further studies are warranted.

Improved diagnosis of Ziehl-Neelsen smear negative tuberculosis using sodium hypochlorite sedimentation method.

BACKGROUND: Bacteriological diagnosis of tuberculosis (TB) is largely dependent on Ziehl-Neelsen (ZN) microscopy. This method has a low sensitivity. Although concentration of sputum with sodium hypochlorite (NaOC1) followed by sedimentation increases the sensitivity of direct smear microscopy, no study has focused on the effect of NaOC1 on smear negative sputum specimens. OBJECTIVE: To establish whether 3.5% NaOC1 sedimentation method specifically improves the diagnosis of Ziehl-Neelsen smear negative tuberculosis. DESIGN: A prospective study. SETTING: Mbagathi District Hospital and Center for Respiratory Diseases Research, Kenya Medical Research Institute. SUBJECTS: Two hundred and thirty confirmed direct ZN smear negative sputum specimens from new TB suspects were analysed. RESULTS: Seventy (30.4%) specimens were culture positive. Of these, 19 were ZN smear positive. The ZN sensitivity, specificity, positive and negative predictive values were 27.1%, 99%, 95% and 76%, respectively, after sedimentation with 3.5% NaOC1. CONCLUSION: Overnight sedimentation using 3.5% NaOC1 significantly improves diagnosis of ZN smear negative TB. This technique has potential to improve diagnosis in TB diagnostic services especially in settings with high burden of dual TB/HIV infection.

Combination of bleach and flourescent microscopy: a milestone in the diagnosis of smear negative tuberculosis.

BACKGROUND: The reliability of direct smear microscopy for diagnosis of tuberculosis has frequently been questioned due to low sensitivity. Treatment of sputum with sodium hypochlorite (NaOCI) has been used to increase sensitivity in many settings. However, no study has established the effect of NaOCI on fluorescent microscopy. OBJECTIVE: To establish whether NaOCI concentration method enhances positivity of fluorescent microscopy smear negative sputum for diagnosis of tuberculosis. DESIGN: A prospective study. SETTING: Mbagathi District Hospital and Centre for Respiratory Diseases Research, Kenya Medical Research Institute. RESULTS: Forty five (22%) specimens were culture positive. Fluorescent microscopy sensitivity was 28.9% and 22.2% after centrifugation and sedimentation with 3.5% NaOCI, respectively (P > 0.05). Sensitivity was 24.4% and 17.8% after centrifugation and sedimentation with 5% NaOCI, respectively (P > 0.05). Although there was no statistical significance difference between the two NaOCI concentration methods, 3.5% NaOCI with centrifugation indicated a higher yield. CONCLUSION: Use of NaOCI significantly enhances positivity of smear negative sputum for diagnosis of tuberculosis when used with fluorescent microscopy. This approach could be recommended for screening all tuberculosis suspects especially in settings with potential smear negative tuberculosis.

Planning for PPM-DOTS implementation in urban slums in Kenya: knowledge, attitude and practices of private health care providers in Kibera slum, Nairobi.

SETTING: Kibera, the largest slum in Nairobi, Kenya. OBJECTIVE: To determine the tuberculosis (TB) knowledge, attitude and practices (KAP) of private health care providers (PHCPs) to identify their training needs and willingness to participate in a National Leprosy and Tuberculosis Control Programme (NLTP) guided TB control effort in the slum. DESIGN AND METHODOLOGY: A cross-sectional survey. The KAP of PHCPs was assessed using an interviewer administered questionnaire. RESULTS: Of 75 PHCPs interviewed, the majority (96.0%) were paramedics; 51 (77.1%) did not consider sputum smear microscopy crucial in patients presenting with prolonged cough or when a chest X-ray was suggestive of TB; of 29 (38.7%) who indicated familiarity with the drugs used in TB treatment, 20 (58.5%) would have chosen the NLTP-recommended regimens for the treatment of the various types of TB; 16 (21.3%) PHCPs indicated that they treated TB, six (37.5%) of whom were not familiar with anti-tuberculosis drug regimens. All the PHCPs referred TB suspects to the public sector for diagnosis. CONCLUSION: This study reveals a significant gap in TB knowledge among the PHCPs in Kibera slum. However, given appropriate training and supervision, there is potential for public-private mix for DOTS implementation in this setting.

Isolation of multidrug-resistant tuberculosis strains in patients from private and public health care facilities in Nairobi, Kenya.

SETTING: Health care facilities in Nairobi, Kenya. OBJECTIVE: To document the presence of multidrug-resistant tuberculosis (MDR-TB) strains in patients from Nairobi between September 1999 and October 2001. DESIGN: Descriptive study. RESULTS: Of the 983 referred patients who submitted sputum for culture and drug susceptibility testing (DST), 59% were males. Two hundred and nine (21.3%) patients had a positive culture, of whom 15.2% had a request for DST against isoniazid, rifampicin, streptomycin and ethambutol. Of these, 65 (43.6%) had an isolate resistant to one or more drugs, while 17 (11.4%) had MDR-TB. Ten (59.0%) cases were referred from public health care facilities while seven (41%) were from the private sector. Sixteen isolates were resistant to all four drugs. All MDR-TB cases but one were from Nairobi. CONCLUSION: The emergence of MDR-TB in Nairobi is a cause for concern. An outbreak would be catastrophic, creating not only increased morbidity and mortality but also a tremendous strain on already limited health care resources. Lack of policies for the treatment and management of MDR-TB and the unavailability of appropriate diagnostic facilities may increase its spread. Efforts to prevent outbreaks of MDR-TB should be emphasised.

Identification of MDR-TB Beijing/W and other Mycobacterium tuberculosis genotypes in Nairobi, Kenya.

SETTING: Suspected tuberculosis (TB) patients in Nairobi, Kenya. OBJECTIVE: To identify the presence of multidrug-resistant (MDR) Beijing/W type and other genotypes of Mycobacterium tuberculosis. METHODS: Thirty-three isolates resistant to one or more drugs (resistance ratio method), including 15 MDR isolates and 40 susceptible isolates selected at random, were analysed by dot-blot hybridisation for mutations associated with resistance to isoniazid, rifampicin, streptomycin and ethambutol. All strains were genotypically classified using spoligotyping. RESULTS: Of the 33 drug-resistant isolates, 21 (64%) were from males and 12 (36%) were from females. Mutations associated with resistance to isoniazid (katG 315) and rifampicin (rpoB526, 531) were confirmed in 83.3% and 100% of the isolates, respectively, and in 87% of the MDR isolates. Mutations were detected in 25% and 71.5% of the isolates resistant to streptomycin (rpsL43) and ethambutol (embB306), respectively. No mutations were detected in drug-susceptible isolates. Spoligotyping grouped the isolates into 25 groups. Ten of these groups corresponded to previously identified strain groups, including seven families in the international database. One of these families (CAS1) comprised six (40%) of the 15 MDR isolates. Another family (Beijing) had six (8.3%) isolates, of which two (33.3%) were MDR (Beijing/W). CONCLUSION: This study is the first in Kenya and the second in sub-Saharan Africa to report the presence of MDR Beijing/W type and other possible drug-resistant outbreak strains. Application of the molecular techniques and markers will allow us to monitor the spread of existing drug-resistant strains and the appearance of new ones.

A comprehensive comparison of Ziehl-Neelsen and fluorescence microscopy for the diagnosis of tuberculosis in a resource-poor urban setting.

SETTING: Nairobi City Council Chest Clinic, Kenya. OBJECTIVES: To establish the efficiency, costs and cost-effectiveness of six diagnostic strategies using Ziehl-Neelsen (ZN) and fluorescence microscopy (FM). DESIGN: A cross-sectional study of 1398 TB suspects attending a specialised chest clinic in Nairobi subjected to three sputum examinations by ZN and FM. Lowenstein-Jensen culture was used as the gold standard. Cost analysis included health service and patient costs. RESULTS: Of 1398 suspects enrolled, 993 (71%) had a complete diagnostic work-up involving three sputum specimens for ZN and FM, culture and chest X-ray (CXR). Irrespective of whether ZN or FM was used on one, two or three smears, the overall diagnostic process detected 92% culture-positive cases. Different strategies affected the ratio of smear-positive to smear-negative TB; however, FM was more sensitive than ZN (P < 0.001). FM performance was not affected by the patient's HIV status. The cost per correctly diagnosed smear-positive case, including savings, was 40.30 US dollars for FM on two specimens compared to 57.70 US dollars for ZN on three specimens. CONCLUSION: The FM method used on one or two specimens is more cost-effective and shortens the diagnostic process. Consequently, more patients can be put on a regimen for smear-positive TB, contributing to improved treatment and reducing transmission.

Tuberculosis re-treatment outcomes within the public service in Nairobi, Kenya.

OBJECTIVES: This study was undertaken to describe treatment outcomes in patients started on a re-treatment drug regimen, assess the quality of follow up procedures and the adequacy of the currently advocated re-treatment drug regimen in Nairobi, Kenya. DESIGN: A retrospective study. SETTING: Mbagathi District Hospital (MDH), Nairobi, a public hospital that serves as the Tuberculosis (Tb) referral centre for Nairobi. MATERIALS AND METHODS: The Tb register at the MDH was used to identify patients who were on the re-treatment regimen for Tb. Case records for these patients were then retrieved. From these sources, information on age, sex, HIV status, previous and current tuberculosis disease and drug regimens, adherence to treatment and treatment outcomes, was obtained. Descriptive statistics was used to analyse the data. RESULTS: Of the total of 4702 patients registered at the MDH between 1996 and 1997, 593 (12.6%) were patients with either recurrent Tb, returning to treatment after default or had failed initial treatment. Of the 593 patients, case records were unavailable for 168 and 17 were children below the age of ten in whom the diagnosis of Tb was uncertain making a total of 185 patients who were excluded from the study. Of the remaining 408 patients, 77 (18.9%) were cured, 61 (15.0%) completed treatment without confirmation of cure, two (0.5%) defaulted, six (1.5%) died and 262 (64.2%) had no outcome information. There were no treatment failures. Treatment success defined as cure or treatment completion was achieved in 94.5% of the 146 patients in whom outcome data were available. HIV positive patients had a statistically significant poorer success rate (34/40, 85%) when compared with HIV negative patients (104/106, 94%), p=0.004. Mycobacterium tuberculosis culture and drug susceptibility testing, was not done. CONCLUSION: The high number of patients with no treatment outcome information at the MDH is worrying, as these patients may harbour drug resistant bacilli and reflects an inadequate follow up service for Tb re-treatment in Nairobi. However, where treatment outcomes could be assessed, the currently advocated re-treatment regimen achieved a high success rate. These observations point to an urgent need to improve Tb documentation and follow up procedures within the public service in Nairobi in order to forestall the emergence and spread of drug resistant Tb.

Laboratory methods for diagnosis and detection of drug resistant Mycobacterium tuberculosis complex with reference to developing countries: a review.

OBJECTIVE: To outline principles, advantages and limitations of the currently available laboratory methods for diagnosis and detection of drug resistance of Mycobacterium tuberculosis complex. DATA SOURCE: Published series of peer reviewed journals and manuals written on laboratory methods that are currently used for diagnosis and detection of drug resistance of Mycobacterium tuberculosis complex were reviewed using the index medicus, pubmed and medline search. Conventional bacteriological microscopy and culture, BACTEC, and molecular-based techniques were included. Basic principles, advantages and limitations of the cited techniques have been highlighted. CONCLUSION: Conventional bacteriological microscopy and culture are usually used for diagnosis of tuberculosis (TB) particularly in developing countries. However, their limited sensitivity, specificity and delayed results make this provision inadequate. Despite the development of quicker and more sensitive novel diagnostic techniques, their complexity and high cost has limited their use in many poor-resource countries. Due to the rapidly growing TB problem in these countries, there is urgent need to assess promising alternative methodologies in settings with high disease prevalence.

Surveillance of drug-resistant tuberculosis and molecular evaluation of transmission of resistant strains in refugee and non-refugee populations in North-Eastern Kenya.

SETTING: Three refugee camp complex clinics and an adjacent non-refugee treatment centre in North-Eastern Kenya. OBJECTIVES: To use conventional and molecular epidemiology tools to determine: 1) the prevalence of drug resistance in newly diagnosed patients with smear-positive pulmonary tuberculosis in refugee and non-refugee populations; 2) risk factors for resistance in the two populations; and 3) whether IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping showed similarities in DNA fingerprinting patterns of drug-resistant isolates that could infer transmission within and between the two populations. RESULTS: Of 241 isolates from the camps, 44 (18.3%) were resistant to one or more drugs, seven of which (2.9%) were multidrug-resistant TB (MDR-TB). Of 88 isolates from the non-refugees, five (5.7%) were resistant to one or more drugs without MDR-TB. Drug resistance was higher in the camps than in the non-refugee population (OR = 3.7; 95%CI 1.42-9.68; P < 0.007). Resistance was significantly higher in one camp compared with the other two, despite a comparable ethnic distribution. Unusually, females were more associated with drug resistance than their male counterparts in both populations (OR = 2.3; 95%CI 1.2-4.8; P = 0.008). There was evidence of transmission of streptomycin-resistant strains in the refugee population. DNA fingerprints of resistant strains from the non-refugee population were unique and different from those in the refugee camps. CONCLUSION: The observed high levels of drug resistance and MDR-TB, combined with evidence of transmission of strains resistant to streptomycin in the refugee population, suggest a need for strengthened TB control programmes in settings with a high risk of developing drug-resistant strains.

Autopsy study of HIV-1-positive and HIV-1-negative adult medical patients in Nairobi, Kenya.

HIV infection has now been consistently identified as the major cause of death in young Africans in both urban and rural areas. In Africa, several studies have defined the clinical presentation of HIV disease but there have only been a limited number of autopsy studies. Because of the scarcity of autopsy data and the possibility of differing type and frequency of opportunistic infections between different geographic locations we set out to study consecutive new adult medical admissions to a tertiary referral hospital in Nairobi and perform autopsies on a sample of HIV-1-positive and HIV-1-negative patients who died in the hospital ward. Basic demographic data were collected on all patients admitted to two acute medical wards over an 11-month period. Final outcome and final clinical diagnoses were recorded at discharge or death. An autopsy examination was requested if the patient died in the ward. Autopsy examination was performed in 75 HIV-1-positive (40 men, 35 women) and 47 HIV-1-negative (28 men, 19 women) adults who died in the hospital. This represented 48.4% of all HIV-1-positive deaths and 33.3% of all HIV-1-negative deaths. Tuberculosis (TB) and bacterial and interstitial bronchopneumonia accounted for 96% of the major pathology in patients found to be HIV-1-positive at autopsy. TB was present in half the HIV-1-positive autopsy patients and was disseminated in over 80% of cases. Meningeal involvement was present in 26% of those with disseminated TB. By contrast, TB was much less common in the HIV-1-negative patients at autopsy in whom bacterial bronchopneumonia and malignancies were the most common pathologies. The type pathology found in the HIV-1-positive autopsy patients was not different than that found in other areas in Africa so far studied.

Specificity of IS6110-based DNA fingerprinting and diagnostic techniques for Mycobacterium tuberculosis complex.

Restriction fragment length polymorphism and hybridization of DNA extracted from Mycobacterium tuberculosis, nontuberculous mycobacteria, and nonmycobacterial species with a probe derived from IS6110 confirmed that IS6110 was specific to M. tuberculosis complex. In addition, DNA amplification with IS6110-specific primers yielded a 181-bp fragment only in DNA from M. tuberculosis complex isolates.

Antituberculosis drug resistance surveillance in Kenya, 1995.

SETTING: Twenty-two of the 42 administrative districts in Kenya. OBJECTIVE: To determine the prevalence of drug resistance in newly diagnosed patients with pulmonary tuberculosis, to determine possible risk factors associated with resistance, and to establish standard routine surveillance of drug resistance. DESIGN: Cross-sectional study. METHODS: Sputum samples from newly diagnosed patients with smear-positive pulmonary tuberculosis were analysed using standard procedures. RESULTS: Of 638 patients, 85% were culture positive for Mycobacterium tuberculosis. Of 491 patients tested for susceptibility to isoniazid, streptomycin, rifampicin and ethambutol, 90.8% had fully sensitive strains and 9.2% had a strain resistant to one or more drugs. Of 445 patients with no history of previous chemotherapy, 6.3% had a resistant strain. Of 46 patients with a history of previous chemotherapy, 37% had a resistant strain. No resistance to either rifampicin or ethambutol was detected. There was a strong association between previous chemotherapy and resistance. Resistance was not associated with age or sex. High concordance between Kenya's results and those of the Mycobacterium Reference Unit in the UK on both drug-sensitive and drug-resistant strains indicates that clinically significant and comparable data can be obtained from laboratories employing unsophisticated and inexpensive standard procedures. CONCLUSION: Rates of initial drug resistance are still low in Kenya. The increase in acquired resistance to isoniazid requires monitoring.

Cost-effectiveness of the polymerase chain reaction versus smear examination for the diagnosis of tuberculosis in Kenya: a theoretical model.

SETTING: A major out-patient tuberculosis clinic in Nairobi, Kenya. OBJECTIVE: To ascertain the cost-effectiveness of the polymerase chain reaction (PCR) for the diagnosis of tuberculosis in an urban setting in a developing country. DESIGN: A cost-effectiveness analysis of PCR and direct smear microscopy examination based on theoretical modelling. The cost-effectiveness was expressed in costs per correctly diagnosed tuberculosis patient for each of the two diagnostic techniques. Data were obtained from the literature, from the staff and the register at the health facility and from structured interviews with patients. Assumptions were made when no data were available. RESULTS: The PCR is expected to be more specific and sensitive than the routine procedure for diagnosis, but it is also more costly. The routine procedure based on direct smear microscopy turned out to be 1.8 times as cost-effective as PCR. CONCLUSION: It is concluded that the PCR method can potentially be a cost-effective screening procedure for tuberculosis, provided that the largest contributing cost component, the costs of the PCR-kit, can be reduced substantially.

Isoniazid preventive therapy for tuberculosis in HIV-1-infected adults: results of a randomized controlled trial.

OBJECTIVES: To determine the efficacy of isoniazid 300 mg daily for 6 months in the prevention of tuberculosis in HIV-1-infected adults and to determine whether tuberculosis preventive therapy prolongs survival in HIV-1-infected adults. DESIGN AND SETTING: Randomized, double-blind, placebo-controlled trial in Nairobi, Kenya. SUBJECTS: Six hundred and eighty-four HIV-1-infected adults. MAIN OUTCOME MEASURES: Development of tuberculosis and death. RESULTS: Three hundred and forty-two subjects received isoniazid and 342 received placebo. The median CD4 lymphocyte counts at enrolment were 322 and 346 x 10(6)/l in the isoniazid and placebo groups, respectively. The overall median follow-up from enrolment was 1.83 years (range, 0-3.4 years). The incidence of tuberculosis in the isoniazid group was 4.29 per 100 person-years (PY) of observation [95% confidence interval (CI) 2.78-6.33] and 3.86 per 100 PY of observation (95% CI, 2.45-5.79) in the placebo group, giving an adjusted rate ratio for isoniazid versus placebo of 0.92 (95% CI, 0.49-1.71). The adjusted rate ratio for tuberculosis for isoniazid versus placebo for tuberculin skin test (TST)-positive subjects was 0.60 (95% CI, 0.23-1.60) and for the TST-negative subjects, 1.23 (95% CI, 0.55-2.76). The overall adjusted mortality rate ratio for isoniazid versus placebo was 1.18 (95% CI, 0.79-1.75). Stratifying by TST reactivity gave an adjusted mortality rate ratio in those who were TST-positive of 0.33 (95% CI, 0.09-1.23) and for TST-negative subjects, 1.39 (95% CI, 0.90-2.12). CONCLUSIONS: Overall there was no statistically significant protective effect of daily isoniazid for 6 months in the prevention of tuberculosis. In the TST-positive subjects, where reactivation is likely to be the more important pathogenetic mechanism, there was some protection and some reduction in mortality, although this was not statistically significant. The small number of individuals in this subgroup made the power to detect a statistically significant difference in this subgroup low. Other influences that may have diluted the efficacy of isoniazid include a high rate of transmission of new infection and rapid progression to disease or insufficient duration of isoniazid in subjects with relatively advanced immunosuppression. The rate of drug resistance observed in subjects who received isoniazid and subsequently developed tuberculosis was low.

No increased prevalence of adrenocortical insufficiency in human immunodeficiency virus-associated tuberculosis.

SETTING: Acute medical wards, Kenyatta National Hospital, Nairobi, Kenya. OBJECTIVE: To determine the prevalence of adrenocortical insufficiency in human immunodeficiency virus (HIV)-1 infected and non-infected patients with tuberculosis. DESIGN: One hundred and seventy-four patients with proven tuberculosis (90 HIV-1 positive and 84 HIV-1 negative) were assessed for adrenocortical insufficiency with a 30 min synacthen stimulation test. RESULTS: Fifty-one percent of those with pulmonary tuberculosis and 56% of those with extra-pulmonary tuberculosis had a subnormal cortisol response. However there was no statistically significant difference between the HIV-1 infected and non-infected patients in either group. CONCLUSION: While an impaired cortisol response is common in tuberculosis, it is no more prevalent in HIV-1 infected patients than non-infected patients with tuberculosis.

Anti-tuberculous initial drug resistance of Mycobacterium tuberculosis in Kenya: a ten-year review.

Our experience at the Respiratory Diseases Research Unit (RDRU), over the last 10 years (1981-1990) on the initial drug resistance pattern, focusing on three drugs viz: isoniazid (H), streptomycin (S) and rifampicin (R) is presented. Records on all isolates of M. tuberculosis from one specimen of every newly diagnosed patient recruited countrywide between 1981-1990 were reviewed. We analyzed records of 6,514 isolates and found that total resistance to the three drugs had increased from 8.9% to 14.4%. Resistance to H alone increased from 6.8% to 10.2% while that of S alone from 0.8% to 1.8%. Resistance to R was between 0.1% and 0.3%. Generally, the increase in the resistance trend to both H and S was statistically significant (p = < 0.05 and 0.03, respectively). Although in our analysis we did not address the possible impact of HIV infection, we hope that these findings form a basis for evaluation of this and other possible factors on the emergence of anti-TB drug resistance in future studies.

PIP: A retrospective review of medical records of 6514 Mycobacterium tuberculosis isolates of newly diagnosed patients at the Respiratory Diseases Research Unit of the Kenya Medical Research Institute between 1981 and 1990 aimed to determine the initial drug-resistance pattern for isoniazid, streptomycin, and rifampicin. Overall resistance increased from 8.9 to 14.4% (p 0.001). The increase in the resistance trend to isoniazid and to streptomycin were statistically significant (6.8-10.2; p 0.05 and 0.8-1.8; p = 0.03, respectively) as well as the trend among isolates resistant to both isoniazid and streptomycin (1.2.4; p = 0.03). The trend was more pronounced during 1987-1990 than during 1981-1986. There was no trend in the resistance to rifampicin alone (0.1-0.3%). Just 4 isolates were resistant to both isoniazid and rifampicin. Only 1 was resistant to both streptomycin and rifampicin. None were resistant to all 3 antibiotics. These first-line drugs are used widely in Kenya. These rates of initial resistance to the drugs are lower than those in other developing countries. The lower resistance rate is unlikely to continue, however, due to higher prevalence of HIV infection and the associated increase in tuberculosis incidence. These findings provide researchers a baseline with which to study M. tuberculosis drug resistance and other risk factors as drug resistance increases in Kenya.