Predictors of sputum culture conversion among patients treated for multidrug-resistant tuberculosis

OBJECTIVE

To identify predictors of initial sputum culture conversion, estimate the usefulness of persistent positive cultures at different time points in predicting treatment failure, and evaluate different definitions of culture conversion for predicting failure among patients with multidrug-resistant tuberculosis (MDR-TB) in five countries, 2000-2004.

METHODS

Predictors of time to conversion were identified using multivariate Cox proportional hazards regression modeling. Receiver operating characteristic curves were plotted to visualize the effect of using different definitions of 'culture conversion' on the balance between sensitivity and specificity.

RESULTS

Overall, 1209/1416 (85%) of patients with baseline positive cultures converted in a median of 3.0 months (interquartile range 2.0-5.0). Independent predictors of less likely conversion included baseline positive smear (hazard ratio [HR] 0.60, 95%CI 0.53-0.68), resistance to pyrazinamide (HR 0.82, 95%CI 0.70-0.96), fluoroquinolones (FQs; HR 0.65, 95%CI 0.51-0.83) or thioamide (HR 0.83, 95%CI 0.71-0.96), previous use of FQs (HR 0.71, 95%CI 0.60-0.83), poor outcome of previous anti-tuberculosis treatment (HR 0.69, 95%CI 0.54-0.88) and alcoholism (HR 0.74, 95%CI 0.63-0.87). The maximum combined sensitivity (84%) and specificity (94%) in predicting treatment failure was based on lack of culture conversion at month 9 of treatment, assuming conversion is defined as five consecutive negative cultures.

CONCLUSION

Patients with identified risk factors were less likely to achieve sputum culture conversion during MDR-TB treatment.

WHO guidelines for the programmatic management of drug-resistant tuberculosis: 2011 update

The production of guidelines for the management of drug-resistant tuberculosis (TB) fits the mandate of the World Health Organization (WHO) to support countries in the reinforcement of patient care. WHO commissioned external reviews to summarise evidence on priority questions regarding case-finding, treatment regimens for multidrug-resistant TB (MDR-TB), monitoring the response to MDR-TB treatment, and models of care. A multidisciplinary expert panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to develop recommendations. The recommendations support the wider use of rapid drug susceptibility testing for isoniazid and rifampicin or rifampicin alone using molecular techniques. Monitoring by sputum culture is important for early detection of failure during treatment. Regimens lasting ≥ 20 months and containing pyrazinamide, a fluoroquinolone, a second-line injectable drug, ethionamide (or prothionamide), and either cycloserine or p-aminosalicylic acid are recommended. The guidelines promote the early use of antiretroviral agents for TB patients with HIV on second-line drug regimens. Systems that primarily employ ambulatory models of care are recommended over others based mainly on hospitalisation. Scientific and medical associations should promote the recommendations among practitioners and public health decision makers involved in MDR-TB care. Controlled trials are needed to improve the quality of existing evidence, particularly on the optimal composition and duration of MDR-TB treatment regimens.

Increased resistance to ciprofloxacin and ofloxacin in multidrug-resistant mycobacterium tuberculosis isolates from patients seen at a tertiary hospital in the Philippines

SETTING

A hospital-based study at the Makati Medical Center, Makati City, Philippines, a hyperendemic area for tuberculosis (TB).

OBJECTIVE

To determine the susceptibility of Mycobacterium tuberculosis to ciprofloxacin and ofloxacin.

DESIGN

Retrospective analysis of drug susceptibility tests (DST) of M. tuberculosis isolated from 1995-2000.

RESULTS

Resistance to ciprofloxacin was 26.8%, ofloxacin 35.3%, and multidrug resistance (MDR) was 17.2%. Of the MDR strains, 51.4% were resistant to ciprofloxacin and ofloxacin. Acquired resistance was significantly higher for all first-line drugs and for ciprofloxacin, but not for ofloxacin. A significant increase in resistance to ciprofloxacin and ofloxacin was noted compared to 1989-1994, while resistance to the firstline drugs was not significantly different.

CONCLUSION

Ciprofloxacin and ofloxacin are now a significantly less effective alternative therapy in tuberculosis, particularly MDR-TB, due to a selection pressure from their widespread use in the treatment of TB and possibly other infections in the community, which is hyperendemic for tuberculosis.

Bacillary disease and health seeking behavior among Filipinos with symptoms of tuberculosis: implications for control

SETTING

Urban and rural communities and urban poor settlements in the Philippines.

OBJECTIVE

To determine bacillary disease and action taking among individuals with symptoms of tuberculosis (TB), and to analyze their implications for TB control.

STUDY DESIGN AND METHOD

Subjects aged 20 years and older were interviewed in the 1997 nationwide stratified multi-cluster survey. Sputum acid-fast smears and cultures were done in subjects with abnormal screening chest radiographs.

RESULTS

Individuals with TB symptoms comprised 18.1% of the population studied. The prevalence of bacillary disease was 39/1000 in symptomatic subjects compared to 13/1000 in asymptomatic subjects. Symptom screening had a 14.3% positive predictive value and a 91.4% negative predictive value for bacillary disease. Significantly more symptomatic than asymptomatic subjects attended chest radiographic screening during the survey. However, in response to their symptoms, the majority (43.0%) took no action or self medicated (31.6%), while 11.8% consulted a private practitioner, 7.5% a public health center, 4.4% a hospital, and 1.7% a traditional healer.

CONCLUSION

Sputum smear examination after symptom screening was acceptable for case finding. The health seeking behavior of subjects with TB symptoms was inappropriate. A health education program and public-private collaboration in directly observed therapy, short course (DOTS) are essential for TB control in the Philippines.

BCG coverage and the annual risk of tuberculosis infection over a 14-year period in the Philippines assessed from the Nationwide Prevalence Surveys

SETTING

A prevalence survey of tuberculosis (TB) infection was undertaken in the Philippines, a developing country in the Western Pacific region.

OBJECTIVE

To determine the bacille Calmette Guerin (BCG) vaccination rate, the prevalence of TB infection and the annual risk of TB infection (ARTI).

METHODS

A nationwide stratified multi-stage cluster survey of 21,960 individuals. BCG scar verification and tuberculin test were performed on those aged > or =2 months. The ARTI was calculated using the prevalence rates of TB infection in children aged 5-9 years.

RESULTS

BCG scars were noted in 66% of the study population. The prevalence of TB infection was 63.4% among unvaccinated individuals. The prevalence rate was higher in males in both urban and rural areas. With both sexes combined, urban and rural communities had similar prevalence rates. In children aged 5-9 years, the prevalence rate was 16.1% (males 17.4%, females 14.9%), corresponding to an ARTI of 2.3% (males 2.5%, females 2.1%).

CONCLUSION

BCG coverage increased substantially between 1981-1983 and 1997. The ARTI, however, was virtually unchanged, indicating that morbidity due to TB continued to be high.

Tuberculosis in the urban poor settlements in the Philippines

SETTING

Urban poor settlements in the Philippines.

OBJECTIVE

To determine the magnitude of the tuberculosis problem in urban poor settlements in comparison with urban areas studied in the Nationwide Tuberculosis Prevalence Survey.

STUDY DESIGN AND METHOD

A multistage cluster survey of BCG scar, tuberculin test, chest radiography and sputum examination for bacillary disease, in urban poor areas.

RESULTS

The prevalences of culture-positive and smear-positive tuberculosis were 17.5 +/- 2.3 (95% CI 13.3-22.4) and 7.9 +/- 2.3 per thousand (95% CI 2.611.5), respectively. Extrapolated to the total population, the rates in the urban poor settlements were 12.4 +/- 1.7 (95% CI 9.6-16.2) and 5.6 +/- 1.6 per thousand population (95% CI 1.3-8.3), respectively. The prevalence of active pulmonary tuberculosis in subjects aged 10 years or more was 66 +/- 5.6/1000 (95% CI 55-77). The BCG vaccination rate was 72%. The overall prevalence of tuberculosis infection was 66%, and 39% in those aged 5-9 years, corresponding to an annual risk of infection (ARI) of 6.5%.

CONCLUSION

The problem of tuberculosis was substantial in the urban poor settlements, and was appreciably worse than that in the general urban population.

The 1997 Nationwide Tuberculosis Prevalence Survey in the Philippines

SETTING

The Philippines is a developing country where tuberculosis (TB) remains a significant public health problem.

OBJECTIVE

To determine the prevalence of TB as a basis for setting the targets of the National Tuberculosis Control Program.

STUDY POPULATION AND METHODS

A multi-stage cluster survey of a random sample of 21960 subjects from 36 clusters nationwide was undertaken from 2 April to 31 July 1997. BCG scar verification and tuberculin testing was performed for subjects aged 2 months and over, and chest radiography screening was done on subjects 10 years and older. Sputum samples were collected from individuals who were initially assessed to have abnormal chest radiographs to determine the prevalence of bacillary tuberculosis. Acid-fast smear by modified Kinyoun's technique and culture on Löwenstein Jensen were done to demonstrate Mycobacterium tuberculosis.

RESULTS

The prevalence of active pulmonary TB was 42/1000 population. The prevalence of culture-positive and smear-positive cases was 8.1 and 3.1/1000, respectively. The prevalence was similar in urban and rural areas.

CONCLUSION

Morbidity from TB remains high. Allowing for methodological differences from the survey in 1981-1983, the prevalence of active pulmonary TB was unchanged. There was only a minimal decrease, of 37% for smear-positive cases and 25% for culture-positive cases, in the 14-year interval.