Peter Oh

Extensively Drug-Resistant Tuberculosis in California, 1993–2006

BACKGROUND Extensively drug-resistant (XDR) tuberculosis (TB) is a global public health emergency. We investigated the characteristics and extent of XDR TB in California to inform public health interventions. METHODS XDR TB was defined as TB with resistance to at least isoniazid, rifampin, a fluoroquinolone, and 1 of 3 injectable second-line drugs (amikacin, kanamycin, or capreomycin). Pre-XDR TB was defined as TB with resistance to isoniazid and rifampin and either a fluoroquinolone or second-line injectable agent but not both. We analyzed TB case reports submitted to the state TB registry for the period 1993-2006. Local health departments and the state TB laboratory were queried to ensure complete drug susceptibility reporting. RESULTS Among 424 multidrug-resistant (MDR) TB cases with complete drug susceptibility reporting, 18 (4.2%) were extensively drug resistant, and 77 (18%) were pre-extensively drug resistant. The proportion of pre-XDR TB cases increased over time, from 7% in 1993 to 32% in 2005 (P = .02)). Among XDR TB cases, 83% of cases involved foreign-born patients, and 43% were diagnosed in patients within 6 months after arrival in the United States. Mexico was the most common country of origin. Five cases (29%) of XDR TB were acquired during therapy in California. All patients with XDR TB had pulmonary disease, and most had prolonged infectious periods; the median time for conversion of sputum culture results was 195 days. Among 17 patients with known outcomes, 7 (41.2%) completed therapy, 5 (29.4%) moved, and 5 (29.4%) died. One patient continues to receive treatment. CONCLUSIONS XDR TB and pre-XDR TB cases comprise a substantial fraction of MDR TB cases in California, indicating the need for interventions that improve surveillance, directly observed therapy, and rapid drug susceptibility testing and reporting.

Interferon-γ Release Assays for Diagnosing Mycobacterium tuberculosis Infection in Renal Dialysis Patients

BACKGROUND AND OBJECTIVES End-stage renal disease (ESRD) patients are at high risk for tuberculosis (TB). IFN-gamma release assays that assess immune responses to specific TB antigens offer potential advantages over tuberculin skin testing (TST) in screening such patients for Mycobacterium tuberculosis infection. This study sought to determine whether IFN-gamma release assay results are more closely associated with recent TB exposure than TST results. DESIGN, SETTING, PARTICIPANTS, AND MEASURES Prospective cohort investigation of patients at a hemodialysis center with a smear-positive case of TB. Patients without a history of TB underwent initial and repeat testing with TST, and with the IFN-gamma assays QuantiFERON-TB Gold (QFT-G) and ELISPOT test. Outcome measures included the prevalence of positive test results, identification of factors associated with positive results, and test result discordance. RESULTS A total of 100 (47% foreign born; median age, 55 yr; age range, 18 to 83 yr) of 124 eligible patients were enrolled. Twenty-six persons had positive TST results, 21 had positive QFT-G results, and 27 had positive ELISPOT results. Patients with TB case contact were likely to have a positive QFT-G result (P = 0.02) and ELISPOT results (P = 0.04), whereas TB case contact was not associated with positive TST results (P = 0.7). Positive TST results were associated with foreign birth (P = 0.04) and having had a TST in the previous year (P = 0.04). CONCLUSIONS Positive IFN-gamma assay results were more closely associated with recent TB exposure than were positive TST results. QFT-G and ELISPOT might offer a better method for detecting TB infection in ESRD patients.

Human Exposure following Mycobacterium tuberculosis Infection of Multiple Animal Species in a Metropolitan Zoo

From 1997 to 2000, Mycobacterium tuberculosis was diagnosed in two Asian elephants (Elephas maximus), three Rocky Mountain goats (Oreamnos americanus), and one black rhinoceros (Diceros bicornis) in the Los Angeles Zoo. DNA fingerprint patterns suggested recent transmission. An investigation found no active cases of tuberculosis in humans; however, tuberculin skin-test conversions in humans were associated with training elephants and attending an elephant necropsy.

Treatment practices, outcomes, and costs of multidrug-resistant and extensively drug-resistant tuberculosis, United States, 2005-2007.

Drug resistance was extensive and care was complex; nevertheless, high rates of treatment completion were achieved albeit at considerable cost.

Determinants of multidrug-resistant tuberculosis clusters, California, USA, 2004-2007.

TOC summary: Type of isoniazid resistance–conferring mutation may be a determinant of genotypic clustering.

Antituberculosis Drug Resistance Acquired During Treatment: An Analysis of Cases Reported in California, 1994–2006

BACKGROUND To inform efforts to prevent antituberculosis drug resistance acquired during treatment, particularly multidrug-resistant (MDR) tuberculosis, we analyzed surveillance records from the US state with the highest morbidity. METHODS Surveillance data from the California tuberculosis registry of cases reported between 1994 and 2006 were examined retrospectively. Crude risks of acquired resistance were estimated. Multivariate logistic regression was used to estimate odds ratios of demographic, clinical, and case management characteristics associated with acquired drug resistance (ADR), and secular trends in the incidence of ADR were assessed. RESULTS One in 688 patients acquired MDR tuberculosis, with crude risks varying greatly by initial drug susceptibility test results: 1 in 1909 if initially susceptible to isoniazid and rifampin, 1 in 113 if initially isoniazid resistant, and 1 in 23 if initially rifampicin resistant. Acquired isoniazid and rifampicin monoresistance occurred in 1 in 1018 and 1 in 1455 patients, respectively. Independent predictors of acquired MDR tuberculosis were initial isoniazid resistance (odds ratio [OR], 19.2; 95% confidence interval [CI], 8.25-44.7; P < .001), initial rifampicin resistance (OR, 35.9; 95% CI, 8.61-150; P < .001), human immunodeficiency virus (HIV) infection (OR, 5.07; 95% CI, 1.73-14.9; P = .003), and cavitary disease in the absence of directly observed therapy throughout therapy (OR, 2.65; 95% CI, 1.05-6.69; P = .04). The annual incidence of ADR declined over the study period. CONCLUSIONS Although ADR is rare and declining in California, its costly consequences warrant improvements in treatment practices. Our findings suggest that we ensure DOT throughout the course of therapy for patients with baseline drug resistance, cavitary disease, or HIV infection.

Characteristics and costs of multidrug-resistant tuberculosis in-patient care in the United States, 2005-2007.

OBJECTIVE A population-based study of 135 multidrug-resistant tuberculosis (MDR-TB) patients reported to the Centers for Disease Control and Prevention (CDC) during 2005-2007 found 73% were hospitalized. We analyzed factors associated with hospitalization. METHODS We assessed statistically significant multivariable associations with US in-patient TB diagnosis, frequency of hospitalization, length of hospital stay, and in-patient direct costs to the health care system. RESULTS Of 98 hospitalized patients, 83 (85%) were foreign-born. Blacks, diabetics, or smokers were more likely, and patients with disseminated disease less likely, to receive their TB diagnosis while hospitalized. Patients aged ⩾65 years, those with the acquired immune-deficiency syndrome (AIDS), or with private insurance, were hospitalized more frequently. Excluding deaths, length of stay was greater for patients aged ⩾65 years, those with extensively drug-resistant TB (XDR-TB), those residing in Texas, those with AIDS, those who were unemployed, or those who had TB resistant to all first-line medications vs. others. Average hospitalization cost per XDR-TB patient (US

A systematic synthesis of direct costs to treat and manage tuberculosis disease applied to California, 2015

285 000) was 3.5 times that per MDR-TB patient (US

Multidrug Resistance Among Persons With Tuberculosis in California, 1994-2003

81 000), in 2010 dollars. Hospitalization episode costs for MDR-TB rank third highest and those for XDR-TB highest among the principal diagnoses. CONCLUSIONS Hospitalization was common and remains a critical care component for patients who were older, had comorbidities, or required complex management due to XDR-TB. MDR-TB in-patient costs are among the highest for any disease.

Increased risk of tuberculosis among foreign-born persons with diabetes in California, 2010-2012

BackgroundThe cost of treating and managing cases of active tuberculosis (TB) disease—from diagnosis to treatment completion—is needed by agencies working on public health budgets, resource allocation and cost-effectiveness analysis. Although components of TB costs have been published in the United States (US), no recent study has assessed overall costs for TB care and potential gaps. To systematically review the US literature for costs of treating and managing cases of active TB disease, adjust these costs to current (2015) values, and assess gaps. We quantified total direct costs—from the perspective of the health care payer—of the treatment and case management of active TB disease. Estimates were based on published figures in the US, and operational data of the California Department of Public Health.ResultThe average direct cost of treating and managing a TB case was