Tuberculosis in Siberia: 2. Diagnosis, chemoprophylaxis and treatment

Treating multidrug-resistant tuberculosis in Tomsk, Russia: developing programs that address the linkage between poverty and disease

Tuberculosis (TB) and multidrug-resistant TB (MDR-TB) are diseases of poverty. Because Mycobacterium tuberculosis exists predominantly in a social space often defined by poverty and its comorbidities--overcrowded or congregate living conditions, substance dependence or abuse, and lack of access to proper health services, to name a few--the biology of this organism and of TB drug resistance is intimately linked to the social world in which patients live. This association is demonstrated in Russia, where political changes in the 1990s resulted in increased socioeconomic inequality and a breakdown in health services. The effect on TB and MDR-TB is reflected both in terms of a rise in TB and MDR-TB incidence and increased morbidity and mortality associated with the disease. We present the case example of Tomsk Oblast to delineate how poverty contributed to a growing MDR-TB epidemic and increasing socioeconomic barriers to successful care, even when available. The MDR-TB pilot project implemented in Tomsk addressed both programmatic and socioeconomic factors associated with unfavorable outcomes. The result has been a strengthening of the overall TB control program in the region and improved case-holding for the most vulnerable patients. The model of MDR-TB care in Tomsk is applicable for other resource-poor settings facing challenges to TB and MDR-TB control.

Rates of latent tuberculosis in health care staff in Russia

BACKGROUND

Russia is one of 22 high burden tuberculosis (TB) countries. Identifying individuals, particularly health care workers (HCWs) with latent tuberculosis infection (LTBI), and determining the rate of infection, can assist TB control through chemoprophylaxis and improving institutional cross-infection strategies. The objective of the study was to estimate the prevalence and determine the relative risks and risk factors for infection, within a vertically organised TB service in a country with universal bacille Calmette-Guérin (BCG) vaccination.

METHODS AND FINDINGS

We conducted a cross-sectional study to assess the prevalence of and risk factors for LTBI among unexposed students, minimally exposed medical students, primary care health providers, and TB hospital health providers in Samara, Russian Federation. We used a novel in vitro assay (for gamma-interferon [IFN-gamma]) release to establish LTBI and a questionnaire to address risk factors. LTBI was seen in 40.8% (107/262) of staff and was significantly higher in doctors and nurses (39.1% [90/230]) than in students (8.7% [32/368]) (relative risk [RR] 4.5; 95% confidence interval [CI] 3.1-6.5) and in TB service versus primary health doctors and nurses: respectively 46.9% (45/96) versus 29.3% (34/116) (RR 1.6; 95% CI 1.1-2.3). There was a gradient of LTBI, proportional to exposure, in medical students, primary health care providers, and TB doctors: respectively, 10.1% (24/238), 25.5% (14/55), and 55% (22/40). LTBI was also high in TB laboratory workers: 11/18 (61.1%).

CONCLUSIONS

IFN-gamma assays have a useful role in screening HCWs with a high risk of LTBI and who are BCG vaccinated. TB HCWs were at significantly higher risk of having LTBI. Larger cohort studies are needed to evaluate the individual risks of active TB development in positive individuals and the effectiveness of preventive therapy based on IFN-gamma test results.

Tuberculosis recurrence and mortality after successful treatment: impact of drug resistance

BACKGROUND

The DOTS (directly observed treatment short-course) strategy for tuberculosis (TB) control is recommended by the World Health Organization globally. However, there are few studies of long-term TB treatment outcomes from DOTS programs in high-burden settings and particularly settings of high drug resistance. A DOTS program was implemented progressively in Karakalpakstan, Uzbekistan starting in 1998. The total case notification rate in 2003 was 462/100,000, and a drug resistance survey found multidrug-resistant (MDR) Mycobacterium tuberculosis strains among 13% of new and 40% of previously treated patients. A retrospective, observational study was conducted to assess the capacity of standardized short-course chemotherapy to effectively cure patients with TB in this setting.

METHODS AND FINDINGS

Using routine data sources, 213 patients who were sputum smear-positive for TB, included in the drug resistance survey and diagnosed consecutively in 2001-2002 from four districts, were followed up to a median of 22 months from diagnosis, to determine mortality and subsequent TB rediagnosis. Valid follow-up data were obtained for 197 (92%) of these patients. Mortality was high, with an average of 15% (95% confidence interval, 11% to 19%) dying per year after diagnosis (6% of 73 pansusceptible cases and 43% of 55 MDR TB cases also died per year). While 73 (74%) of the 99 new cases were "successfully" treated, 25 (34%) of these patients were subsequently rediagnosed with recurrent TB (13 were smear-positive on rediagnosis). Recurrence ranged from ten (23%) of 43 new, pansusceptible cases to six (60%) of ten previously treated MDR TB cases. MDR M. tuberculosis infection and previous TB treatment predicted unsuccessful DOTS treatment, while initial drug resistance contributed substantially to both mortality and disease recurrence after successful DOTS treatment.

CONCLUSIONS

These results suggest that specific treatment of drug-resistant TB is needed in similar settings of high drug resistance. High disease recurrence after successful treatment, even for drug-susceptible cases, suggests that at least in this setting, end-of-treatment outcomes may not reflect the longer-term status of patients, with consequent negative impacts for patients and for TB control.

Variability in interpretation of chest radiographs among Russian clinicians and implications for screening programmes: observational study

OBJECTIVE

To determine variability in interpretation of chest radiographs among tuberculosis specialists, radiologists, and respiratory specialists.

DESIGN

Observational study.

SETTING

Tuberculosis and respiratory disease services, Samara region, Russian Federation.

PARTICIPANTS

101 clinicians involved in the diagnosis and management of pulmonary tuberculosis and respiratory diseases.

MAIN OUTCOME MEASURES

Interobserver and intraobserver agreement on the interpretation of 50 digital chest radiographs, using a scale of poor to very good agreement (kappa coefficient: < or = 0.20 poor, 0.21-0.40 fair, 0.41-0.60 moderate, 0.61-0.80 good, and 0.81-1.00 very good).

RESULTS

Agreement on the presence or absence of an abnormality was fair only (kappa = 0.380, 95% confidence interval 0.376 to 0.384), moderate for localisation of the abnormality (0.448, 0.444 to 0.452), and fair for a diagnosis of tuberculosis (0.387, 0.382 to 0.391). The highest levels of agreement were among radiologists. Level of experience (years of work in the specialty) influenced agreement on presence of abnormalities and cavities. Levels of intraobserver agreement were fair.

CONCLUSIONS

Population screening for tuberculosis in Russia may be less than optimal owing to limited agreement on interpretation of chest radiographs, and may have implications for radiological screening programmes in other countries.

The diagnosis and management of multiple-drug-resistant-tuberculosis at the beginning of the new millenium

Multiple-drug-resistant tuberculosis (MDRTB) is more difficult to treat and the treatment is less likely to produce favourable results compared to treatment of drug-sensitive disease. Success requires close co-operation between the laboratory, which defines a case as MDRTB, and the clinical team, who will treat it as well as the public health staff who will address aspects of contact tracing and institutional cross-infection. National surveys have indicated that MDRTB occurs at a higher rate in some countries such as Estonia and Latvia (14.1% and 9% respectively, in 1998) and Russia (although there are only limited validated data). In contrast, in Western Europe and in some countries of Eastern Europe, such as the Czech Republic, Slovenia, Slovakia and Poland with good tuberculosis (TB) prevention and treatment programmes, the combined MDRTB prevalence was 1% or less. The early diagnosis of MDRTB and case management by experienced teams from the outset remains the best hope clinically for these patients. Adequately supervised and prolonged combination chemotherapy is essential, with drug choice governed mainly by quality-controlled in vitro drug susceptibility data. There is a more limited role for surgery, and immunomodulating therapy, such as the use of gamma-interferon, may have a useful adjunct role. Clearly the most important therapeutic modality for MDRTB is to treat drug-sensitive TB correctly in the first instance and prevent the emergence of resistant TB.

The global tuberculosis situation. Progress and problems in the 20th century, prospects for the 21st century

Mycobacterium tuberculosis has been identified in prehistoric remains of humans. Despite references to TB by Hippocrates and Galen, humankind had limited understanding of and few tools to defend itself against TB until the later 19th century. Subsequently, landmark advances in the 20th century provided the means to control and prevent this disease. At the same time, epidemiological developments and fundamental problems related to human behavior, socioeconomic conditions, and political circumstances continue to thwart efforts to diminish the burden of suffering and death caused by TB. This article reviewed some of these issues including the global failure of TB control in the late 20th century, the worldwide emergence of drug-resistant TB, the extensive spread of HIV infection and its impact on TB incidence; and changing health care and political environments. The obstacles to TB control remain and will remain challenges in the coming years. Still, recent developments in immunology, biochemistry, and molecular biology suggest that new knowledge and tools are just around the corner. These will enhance the ability to conquer this microbe by the end of the current century.

Kanamycin susceptibility testing of Mycobacterium tuberculosis using Mycobacterium Growth Indicator Tube and a colorimetric method

Two novel systems were evaluated for performing indirect kanamycin susceptibility tests on 72 strains of Mycobacterium tuberculosis. The microplate Alamar blue colorimetric method (breakpoint, 2.5 microg/ml) and the Mycobacterium Growth Indicator Tube (MGIT) system (breakpoint, 5.0 microg/ml) both produced 98.6% agreement when compared with the conventional proportion method performed on 7H10 agar using 5.0 microg of kanamycin/ml. Both systems provided results within an average of 1 week.

Comparison of the effectiveness of WHO short-course chemotherapy and standard Russian antituberculous regimens in Tomsk, western Siberia

BACKGROUND

There has been a resurgence of tuberculosis in Russia in the past decade. Traditional Russian services for treatment of tuberculosis are very different from those in the west. We aimed to compare the effects of WHO short-course chemotherapy with standard Russian antituberculous regimens.

METHODS

New tuberculosis patients aged 18 years or older were included in a trial and systematically allocated to traditional Russian tuberculosis treatments or WHO short-course chemotherapy in the two largest tuberculosis diagnostic and treatment centres of Tomsk Oblast, western Siberia. Standard WHO tuberculosis outcomes and rates of sputum conversion were used as primary outcomes. Analyses were by intention-to-treat.

FINDINGS

646 new cases were enrolled into the trial, of which 356 patients were given Russian tuberculosis treatment (155 smear positive) and 290 were given WHO short-course chemotherapy (155 smear positive). There was no statistical difference between the proportion cured or completing treatment (63% for both groups [difference in proportion=0%, 95% CI -11 to 11%]); or dying (short-course chemotherapy, 8% vs Russian, 11% [difference in proportion=-3%, 95% CI -9 to 4%]). There was no statistical difference with respect to sputum conversion rate at 6 months (91% vs 85% [difference in proportion=6%, 95% CI -2 to 13%]). Overall, outcomes were worse among patients with multidrug resistant isolates than non-resistant isolates.

INTERPRETATIONS

WHO short-course chemotherapy treatment for tuberculosis can work well in Russia.

Drug-resistant tuberculosis: worldwide trends, problems specific to Eastern Europe and other hotspots, and the threat to developing countries

Although it had been appreciated that high levels of antituberculous drug resistance existed in some regions of the world, the full extent of the problem was not known. A combined initiative by the World Health Organization and the International Union Against Tuberculosis and Lung Disease was launched in 1994 to address this. A second report was issued in March 2000, in which surveillance of drug resistance had been extended to 72 countries and regions. A number of drug resistant "hotspots," where there are high levels of combined multidrug-resistant tuberculosis (> 3% prevalence), have been identified. Particular areas of concern are countries of the former Soviet Union, India, and China, because these countries have the highest burden of multidrug-resistant tuberculosis. For the first time, information on trends in global drug resistance is available.

Survey of drug-resistant tuberculosis in northwestern Russia from 1984 through 1994

The morbidity, mortality, and relapse rates of tuberculosis have increased in the Russian Federation since 1991. Increased drug resistance may be one reason for the weakened efficacy of local tuberculosis treatments. Laboratory data on tuberculosis resistance were collected from a survey area that included two republics and seven other administrative regions (oblasts) with a total population of more than 14 million. Susceptibility data from 1991 through 1994 were available from all nine regions; data on resistance to individual drugs and data from 1984 through 1994 were available from the Leningrad region and the city of St. Petersburg. From 1991 through 1994. the annual notification rate of tuberculosis increased in the survey area by 53.7% (from 25.1 to 38.6 cases per 100000 inhabitants), tuberculosis mortality doubled (from 4.4 to 9.2 deaths per 100000), and primary resistance to at least one drug increased from 17% (95% CI, 14.9-19.9) to 24% (95% CI, 22.2.-25.8). The prevalence of primary resistance to at least isoniazid and rifampin (multidrug resistance) was 5.1% in the Leningrad region in 1992 through 1994. The proportion of pulmonary isolates with secondary multidrug resistance increased from 21.6% (95% CI 7.9-25.3%) in the period 1984-1994 to 33% (95% CI 29.7-36.3%) in 1989-1994. Even if these figures are biased upwards because of selection, it can be concluded that secondary resistance to tuberculosis drugs was already prevalent in northwestern Russia ten years ago. Since then, a distinct shift towards multidrug resistance has occurred. The lower prevalence of primary multidrug resistance raises hopes that the resistance problem can be controlled with properly designed and monitored therapeutic measures.