Identifying multidrug resistance in previously treated tuberculosis patients: a mixed-methods study in Cambodia

SETTING

Previously treated tuberculosis (TB) patients are a priority for drug susceptibility testing (DST) to identify cases with multidrug-resistant TB (MDR-TB). A Cambodia study found that one third of smear-positive previously treated patients had DST results.

OBJECTIVE

To quantify the gaps in the detection of MDR-TB in previously treated TB patients in Cambodia, and describe health workers' perspectives on barriers, facilitators and potential interventions.

DESIGN

Analysis of Cambodia's 2004-2012 case notifications and semi-structured interviews with stakeholders.

RESULTS

The proportion of previously treated notifications varied significantly across provinces in 2010-2012. If there had been no attrition along the path to detecting MDR-TB among smear-positive notified cases in 2012, an estimated 75 additional MDR-TB cases could have been identified, which would double the number actually detected. Most were lost due to misclassification of previously treated patients as 'new'. Barriers include patients' reluctance to disclose and staff difficulty in eliciting treatment history, partly attributed to the availability of streptomycin (SM) only in hospitals. Facilitators include collection of sputum for DST even if previously treated patients are not receiving SM, streamlining sputum transportation and prompt reporting of results.

CONCLUSION

Improved monitoring, supportive staff supervision and training, patient education, and correct classification of previously treated cases are essential for improving the detection of MDR-TB.

Plasminogen-stimulated airway smooth muscle cell proliferation is mediated by urokinase and annexin A2, involving plasmin-activated cell signalling

BACKGROUND AND PURPOSE

The conversion of plasminogen into plasmin by interstitial urokinase plasminogen activator (uPA) is potentially important in asthma pathophysiology. In this study, the effect of uPA-mediated plasminogen activation on airway smooth muscle (ASM) cell proliferation was investigated.

EXPERIMENTAL APPROACH

Human ASM cells were incubated with plasminogen (0.5-50 μg·mL(-1) ) or plasmin (0.5-50 mU·mL(-1) ) in the presence of pharmacological inhibitors, including UK122, an inhibitor of uPA. Proliferation was assessed by increases in cell number or MTT reduction after 48 h incubation with plasmin(ogen), and by earlier increases in [(3) H]-thymidine incorporation and cyclin D1 expression.

KEY RESULTS

Plasminogen (5 μg·mL(-1) )-stimulated increases in cell proliferation were attenuated by UK122 (10 μM) or by transfection with uPA gene-specific siRNA. Exogenous plasmin (5 mU·mL(-1) ) also stimulated increases in cell proliferation. Inhibition of plasmin-stimulated ERK1/2 or PI3K/Akt signalling attenuated plasmin-stimulated increases in ASM proliferation. Furthermore, pharmacological inhibition of cell signalling mediated by the EGF receptor, a receptor trans-activated by plasmin, also reduced plasmin(ogen)-stimulated cell proliferation. Knock down of annexin A2, which has dual roles in both plasminogen activation and plasmin-signal transduction, also attenuated ASM cell proliferation following incubation with either plasminogen or plasmin.

CONCLUSIONS AND IMPLICATIONS

Plasminogen stimulates ASM cell proliferation in a manner mediated by uPA and involving multiple signalling pathways downstream of plasmin. Targeting mediators of plasminogen-evoked ASM responses, such as uPA or annexin A2, may be useful in the treatment of asthma.

Multidrug resistance in new tuberculosis patients: burden and implications

In 2010, 30 countries with anti-tuberculosis drug resistance surveillance data were each estimated to have more than 700 multidrug-resistant tuberculosis (MDR-TB) cases among their notified TB cases. New TB patients comprised a median of 54% (interquartile range 45-67) of the MDR-TB cases. The occurrence of MDR-TB in a new TB patient is a warning sign that MDR-TB is spreading in a community. While MDR-TB case-finding efforts should first prioritize previously treated patients, reaching universal access requires rapidly adding other risk groups, and then all new TB patients. Epidemiological data as presented in this paper can help inform country scale-up plans.

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.

Predicting outcomes and drug resistance with standardised treatment of active tuberculosis

New World Health Organization guidelines recommend initial treatment of active tuberculosis (TB) with a 6-month regimen utilising rifampin throughout. We have modelled expected treatment outcomes, including drug resistance, with this regimen, compared to an 8-month regimen with rifampin for the first 2 months only, followed by standardised retreatment. A deterministic model was used to predict treatment outcomes in hypothetical cohorts of 1,000 new smear-positive cases from seven countries with varying prevalence of initial drug resistance. Model inputs were taken from published systematic reviews. Predicted outcomes included number of deaths, failures and relapses, plus the proportion with drug resistance. Sensitivity analyses examined different risks of acquired drug resistance. Compared to use of the standardised 8-month regimen, for every 1,000 new TB cases treated with the 6-month regimen we predict that 48-86 fewer persons will require retreatment, and 3-12 deaths would be avoided. However, the proportion failing or relapsing after retreatment is predicted to be higher, because with the 6-month regimen 50-94% of failures and 3-56% of relapses will have multidrug-resistant TB. We predict substantial public health benefits from changing from the 8-month to the 6-month regimen. However in almost all settings the current standardised retreatment regimen will no longer be adequate.

Professional development in reproductive and sexual health--a pilot study from Suffolk, UK

Staff from two neighbouring trusts working in the fields of family planning and sexual health worked together to develop joint guidelines and from this evolved a training initiative. It was acknowledged that staff were either primarily trained in family planning or in the management of sexually transmitted infections (ST1) and therefore the training would be interdisciplinary. In line with current educational thinking it was also decided to make it multiprofessional. A pilot training project was therefore set up to answer the question 'can self directed learning combined with facilitated small group study sessions provide theoretical updating for a range of health professionals within the field of reproductive and sexual health'. The project aimed to increase theoretical knowledge of contraception, sexually transmitted infections and termination of pregnancy for all relevant nursing and medical staff working within the two trusts. The stated outcome of the project was for all staff to achieve a wider core knowledge of the identified topics, regardless of whether their primary training and knowledge base was in family planning or sexually transmitted infection. The project spanned five months and offered professional development packages in hormonal contraception, non-hormonal contraception, termination of pregnancy, bacterial and minor STIs and viral STIs. The pilot project was well received and the process was shown to be an effective way of increasing the knowledge base. The knowledge shift was greatest in the opposing discipline to the primary discipline of each participant. There were added advantages in team building for staff within the same trust and networking across trusts. The strengths and weaknesses of the process were identified and used to develop ideas for future professional development initiatives.

Tuberculosis in children and adolescents: California, 1985 to 1995

OBJECTIVES

To describe the epidemiology and clinical characteristics of tuberculosis (TB) among children and adolescents and to define children at risk for TB.

SETTING

4607 children 0 to 14 years of age and 1615 adolescents 15 to 19 years of age reported with TB in California.

METHODS

We analyzed surveillance data reported to the California Department of Health Services TB Control Branch from 1985 through 1995.

RESULTS

TB cases increased 22% among children 0 to 4 years of age and 66% among children 5 to 14 from 1985 through 1995. Case rates were highest among children 0 to 4 years of age (13/ 100000 children), but declined from 1993 to 1995, except for black children 0 to 4 years of age. Minority children 0 to 14 years of age had case rates 6- to 34-fold higher than did white children. Pulmonary TB was the most common site of disease in all age groups (71 to 82%). TB meningitis was most common in children 0 to 4 years of age (5%). Most children (64%) did not have cultures done; however, among culture-proved cases isoniazid-resistant Mycobacterium tuberculosis was isolated in 7%. Adolescents were more likely to have cavitary pulmonary disease (24%), to be foreign-born (78%) or homeless (4%) and to have an isoniazid-resistant strain isolated (13%) than were children 0 to 14 years of age (P < 0.05).

CONCLUSIONS

TB in children and adolescents increased substantially in the mid-1980s and early 1990s. Pediatric TB remains a serious health problem, especially among minority children and adolescents. Our findings indicate that TB control programs need improved strategies to prevent infection and detect disease in this population.

Outbreak of drug-resistant tuberculosis with second-generation transmission in a high school in California

BACKGROUND

In spring 1993, four students in a high school were diagnosed with tuberculosis resistant to isoniazid, streptomycin, and ethionamide.

METHODS

To investigate potential transmission of drug-resistant tuberculosis, a retrospective cohort study with case investigation and screening by tuberculin skin tests and symptom checks was conducted in a high school of approximately 1400 students. Current and graduated high-school students were included in the investigation. DNA fingerprinting of available isolates was performed.

RESULTS

Eighteen students with active tuberculosis were identified. Through epidemiologic and laboratory investigation, 13 cases were linked; 8 entered 12th grade in fall 1993; 9 of 13 had positive cultures for Mycobacterium tuberculosis with isoniazid, streptomycin, and ethionamide resistance, and all 8 available isolates had identical DNA fingerprints. No staff member had tuberculosis. One student remained infectious for 29 months, from January 1991 to June 1993, and was the source case for the outbreak. Another student was infectious for 5 months before diagnosis in May 1993 and was a treatment failure in February 1994 with development of rifampin and ethambutol resistance in addition to isoniazid, streptomycin, and ethionamide. In the fall 1993 screening, 292 of 1263 (23%) students tested had a positive tuberculin skin test. Risk of infection was highest among 12th graders and classroom contacts of the two students with prolonged infectiousness. An additional 94 of 928 (10%) students tested in spring 1994 had a positive tuberculin skin test; 22 were classroom contacts of the student with treatment failure and 21 of these had documented tuberculin skin test conversions.

CONCLUSION

Extensive transmission of drug-resistant tuberculosis was documented in this high school, along with missed opportunities for prevention and control of this outbreak. Prompt identification of tuberculosis cases and timely interventions should help reduce this public health problem.

A population-based study determining the incidence of tuberculosis attributable to HIV infection

Although the tuberculosis (TB) epidemic has been attributed in part to the AIDS epidemic, few studies in the United States have measured the risk attributable to HIV infection. We linked the TB registry of Alameda County, California, 1985 to 1994, with the AIDS registry, 1982 to 1994. We defined a person with TB and HIV infection as a patient in the TB registry with the same name, race/ethnicity, gender, and date of birth as a patient in the AIDS registry. We used population and HIV seroprevalence estimates to determine the HIV-seropositive and -seronegative population at risk of TB in 1994. Of 1990 TB cases reported by Alameda County from 1985 to 1994, 116 (5.8%) had an AIDS diagnosis. Among 25- to 44-year-old TB patients, 25.2% of U.S.-born men and 8.4% of U.S.-born women had an AIDS diagnosis. In 1994, the estimated TB incidence rate in persons with HIV infection was 198.1 per 100,000 versus a rate of 13.9 of 100,000 among persons without HIV infection (rate ratio, 13.8; 95% confidence interval, 8.0, 23.8). In 1994, 93% of TB cases among HIV seropositive persons, 6.4% of all TB cases, and 16.7% of TB cases aged 25 to 44 years were attributable to HIV infection. The high attributable risk underscores the impact of HIV on the TB epidemic. All persons with HIV infection should be screened for TB, and persons with TB infection should be screened for HIV infection. TB/HIV coinfected patients should be provided with TB preventive therapy.

Detention of persistently nonadherent patients with tuberculosis

CONTEXT

Patients with tuberculosis (TB) who are persistently nonadherent to treatment present a public health risk. In 1993, California created a new civil detention process and allowed detention of noninfectious but persistently nonadherent patients.

OBJECTIVES

To determine (1) which patients TB controllers attempt to detain, (2) how often and where patients are detained, and (3) how many of these patients complete TB treatment.

DESIGN

Case series with cross-sectional comparison to other adult TB patients in the study counties.

SETTING

Twelve California counties with the largest number of new TB cases reported in 1994.

SUBJECTS

All patients whom TB controllers sought to detain during 1994 and 1995 because of persistent nonadherence to treatment.

DATA SOURCES

Public health records, interviews with county TB officials, and Reports of Verified Cases of Tuberculosis to the California Tuberculosis Control Branch.

RESULTS

Tuberculosis controllers sought the civil detention or arrest of 67 patients during the study period (1.3% of adult TB patients with the same disease sites). Forty-six percent of these patients were homeless, 81% had drug or alcohol abuse, and 28% had mental illness. Tuberculosis controllers sought civil detention of 15 patients. Fourteen patients were detained (median length of detention, 14.5 days). Tuberculosis controllers sought to arrest 62 patients during the study period. Fifty-three patients were arrested (median time in jail, 83 days). In 10 cases, both civil and criminal detention were attempted. We analyzed completion of therapy after excluding patients who were not detained or who died or moved. Overall, 41 (84%) of the remaining 49 detained patients completed therapy. Of the patients who completed therapy, only 17 were detained until treatment was completed. Compared with other TB patients in these counties, detained patients had 4 times the proportion lost to follow-up and half the proportion completing therapy within 12 months.

CONCLUSION

Further improvements in the care of persistently nonadherent patients may require more psychosocial services, appropriate facilities for civil detention, and detaining patients long enough to assure completion of treatment.

Drug-resistant Mycobacterium tuberculosis in California, 1991 to 1992

To determine the proportion and distribution of drug-resistant Mycobacterium tuberculosis in California, we surveyed all California counties for drug-susceptibility test results for initial isolates from tuberculosis cases counted during the first quarters of 1991 and 1992. Overall, drug-susceptibility test results were not available for 17% of isolates. Among isolates with available test results, the proportion with resistance to isoniazid averaged 8.7%, and the proportion with resistance to at least 2 drugs, multidrug resistance, averaged 5.9% during these two quarters. The proportion of isolates with drug resistance did not change substantially during these time periods. The proportion with combined isoniazid and rifampin resistance remained stable at about 1.1%. Among persons whose isolates were tested for drug resistance, those with a known previous diagnosis of tuberculosis (relative risk [RR] = 2.6; 95% confidence interval [CI], 1.6 to 4.3; P < .01) and persons who were foreign born (RR = 1.7; 95% CI, 1.1 to 2.7; P = .014) were more likely to have isoniazid-resistant organisms. These statewide data suggest that the initial tuberculosis treatment regimen in California should include 4 antituberculosis drugs, as recommended by the American Thoracic Society and the Centers for Disease Control and Prevention for areas with a prevalence of isoniazid resistance of 4% or greater. The lack of test results for 1 in 6 patients with tuberculosis suggests the need for improved physician and laboratorian education to implement the recommendations that drug susceptibility be tested on all initial isolates.

Chelation therapy in workers with lead exposure

Occupational lead overexposure remains a major problem. To evaluate the settings in which physicians appropriately prescribe chelation therapy for lead exposure, 7 cases were identified from physician phone calls and mandatory laboratory reporting of elevated blood lead levels to the California Department of Health Services. In the 2 workers with the highest blood lead levels (both of whom had severe symptoms), treatment was indicated. Physicians inappropriately prescribed chelating agents to workers with ongoing lead exposure as prophylaxis against rising blood lead levels and to treat atherosclerotic heart disease. Workers' personal physicians identified lead overexposure in 5 of the 7 cases. Workplace lead medical surveillance programs mandated by the federal Occupational Safety and Health Administration were inadequate in all 5 of the workplaces where information was available.

Occupational asthma in a pesticides manufacturing worker

A 34-year-old chemical manufacturing worker had new onset of work-related asthma after several years of exposure to the fungicide, captafol. On specific bronchial challenge testing, he demonstrated a marked and persistent fall in FEV1. Cessation of exposure resulted in improved symptoms and pulmonary function. The delay in symptoms after several years of workplace exposure and the dual reaction demonstrated on specific bronchial challenge testing suggest sensitization to some component of technical-grade captafol, but an IgE response was not detected.

Lead exposure in the construction industry: results from the California Occupational Lead Registry, 1987 through 1989

The construction industry is exempt from the medical monitoring portions of the US Federal Occupational Safety and Health Administration General Industry Lead Standard. Of 28 construction workers reported to the California Occupational Lead Registry through March 1989, 11 (39%) had blood lead levels of 2.90 mumol/L (60 micrograms/dL) or greater, the level at which immediate removal from lead exposure is mandated in nonconstruction industries. Many workers had not been warned of possible lead exposure. The exemption of the construction industry from the General Industry Lead Standard should be reconsidered.

Atopy and airways reactivity in animal health technicians. A pilot study

Smoking, response to allergen skin testing, and nonspecific airways reactivity in students entering a career program for animal health technicians (AHT) were studied at their entrance and 7 months into the program to determine whether such persons provide a suitable cohort to overcome the selection biases accompanying investigations of occupational asthma. Previous occupational exposure to animals (65%) was associated positively with allergic symptoms but negatively with skin response to animal allergens and to airway hyperreactivity (AR). AHTs remaining in the program were more likely than those dropping out to have (1) worked with animals, (2) positive skin responsiveness to animal allergens, and (3) AR; the latter was significantly associated with positive skin-test responses to animal allergen testing. This study demonstrates that significant exposure to animals may have occurred among workers entering animal-handling careers. Additionally, competing "healthy" and "resistant" worker effects operate among AHTs to influence the prevalence of occupational asthma in this population.