Use and efficacy of tuberculosis infection control practices at hospitals with previous outbreaks of multidrug-resistant tuberculosis.

OBJECTIVE: To evaluate the implementation and efficacy of selected Centers for Disease Control and Prevention guidelines for preventing spread of Mycobacterium tuberculosis. DESIGN: Analysis of prospective observational data. SETTING: Two medical centers where outbreaks of multidrug-resistant tuberculosis (TB) had occurred. PARTICIPANTS: All hospital inpatients who had active TB or who were placed in TB isolation and healthcare workers who were assigned to selected wards on which TB patients were treated. METHODS: During 1995 to 1997, study personnel prospectively recorded information on patients who had TB or were in TB isolation, performed observations of TB isolation rooms, and recorded tuberculin skin-test results of healthcare workers. Genetic typing of M tuberculosis isolates was performed by restriction fragment-length polymorphism analysis. RESULTS: We found that only 8.6% of patients placed in TB isolation proved to have TB; yet, 19% of patients with pulmonary TB were not isolated on the first day of hospital admission. Specimens were ordered for acid-fast bacillus smear and results received promptly, and most TB isolation rooms were under negative pressure. Among persons entering TB isolation rooms, 44.2% to 97.1% used an appropriate (particulate, high-efficiency particulate air or N95) respirator, depending on the hospital and year; others entering the rooms used a surgical mask or nothing. We did not find evidence of transmission of TB among healthcare workers (based on tuberculin skin-test results) or patients (based on epidemiological investigation and genetic typing). CONCLUSIONS: We found problems in implementation of some TB infection control measures, but no evidence of healthcare-associated transmission, possibly in part because of limitations in the number of patients and workers studied. Similar evaluations should be performed at hospitals treating TB patients to find inadequacies and guide improvements in infection control.

Simultaneous infection with multiple strains of Mycobacterium tuberculosis.

Drug-susceptible and drug-resistant isolates of Mycobacterium tuberculosis were recovered from 2 patients, 1 with isoniazid-resistant tuberculosis (patient 1) and another with multidrug-resistant tuberculosis (patient 2). An investigation included patient interviews, record reviews, and genotyping of isolates. Both patients worked in a medical-waste processing plant. Transmission from waste was responsible for at least the multidrug-resistant infection. We found no evidence that specimens were switched or that cross-contamination of cultures occurred. For patient 1, susceptible and isoniazid-resistant isolates, collected 15 days apart, had 21 and 19 restriction fragments containing IS6110, 18 of which were common to both. For patient 2, a single isolate contained both drug-susceptible and multidrug-resistant colonies, demonstrating 10 and 11 different restriction fragments, respectively. These observations indicate that simultaneous infections with multiple strains of M. tuberculosis occur in immunocompetent hosts and may be responsible for conflicting drug-susceptibility results, though the circumstances of infections in these cases may have been unusual.

Risk factors for positive mantoux tuberculin skin tests in children in San Diego, California: evidence for boosting and possible foodborne transmission.

OBJECTIVES: Source case finding in San Diego, California, rarely detects the source for children with tuberculosis (TB) infection or disease. One third of all pediatric TB isolates in San Diego are Mycobacterium bovis, a strain associated with raw dairy products. This study was conducted to determine risk factors for TB infection in San Diego. DESIGN: Case-control study of children /=10 mm) Mantoux skin test (TST) were matched by age to 1 to 2 children with negative TST from the same clinic. We assessed risk factors for TB infection through parental interview and chart review. RESULTS: A total of 62 cases and 97 controls were enrolled. Eleven cases and 25 controls were excluded from analysis because of previous positive skin tests. Compared with controls, cases were more likely to have received BCG vaccine (73% vs 7%, odds ratio [OR] 44), to be foreign born (35% vs 11%, OR 4.3), and to have eaten raw milk or cheese (21% vs 8%, OR 3.76). The median time between the most recent previous TST and the current test was 12 months for cases and 25 months for controls. Other factors associated with a positive TST included foreign travel, staying in a home while out of the country, and having a relative with a positive TST. There was no association between contact with a known TB case. In a multivariable model, receipt of BCG, contact with a relative with a positive TST, and having a previous TST within the past year were independently associated with TB infection. CONCLUSIONS: We identified several new or reemerging associations with positive TST including cross border travel, staying in a foreign home, and eating raw dairy products. The strong associations with BCG receipt and more recent previous TST may represent falsely positive reactions, booster phenomena, or may be markers for a population that is truly at greater risk for TB infection. Unlike studies conducted in nonborder areas, we found no association between positive TB skin tests and contact with a TB case or a foreign visitor. Efforts to control pediatric TB in San Diego need to address local risk factors including consumption of unpasteurized dairy products and cross-border travel. The interpretation of a positive TST in a young child in San Diego who has received BCG is problematic.

Tuberculosis cases reported among migrant farm workers in the United States, 1993-97.

Migrant farm workers (MFWs) are considered a high-risk group for tuberculosis. MFW tuberculosis cases reported to the Centers for Disease Control and Prevention represented 1 percent of all reported tuberculosis cases from 1993 to 1997. Most of these cases (70 percent) were reported from Florida, Texas, and California. MFW tuberculosis cases were more likely to be male, foreign-born, or Hispanic and to have a history of alcohol abuse and homelessness than were non-MFWs. Most (79 percent) foreign-born MFWs were from Mexico. HIV status was poorly reported, with results available for only 28 percent of MFW and 33 percent of non-MFW cases. Of the MFWs tested, 28 percent were HIV infected, whereas 34 percent of non-MFWs were HIV infected. Twenty percent of MFWs move or are lost to follow-up before completing therapy; these cases pose a management challenge for the nation's tuberculosis control efforts.

Completeness and timeliness of tuberculosis case reporting. A multistate study.

BACKGROUND: Tuberculosis (TB) control activities are contingent on the timely identification and reporting of cases to public health authorities to ensure complete assessment and appropriate treatment of contacts and identification of secondary cases. We report the results of a multistate evaluation of completeness and timeliness of reporting of TB cases in the United States during 1993 and 1994. METHODS: To determine completeness of TB reporting, laboratory log books, death certificates, hospital discharge, Medicaid databases, and pharmacy databases were reviewed in seven states to identify possible unreported cases. Timeliness of TB reporting was calculated using the number of days between date of TB diagnosis and date of report to the local or state health department. Cases reported >7 days after diagnosis were considered to have delayed reporting. RESULTS: Of 2711 cases identified through review of secondary data sources, 14 (0.5%) were previously unreported to public health. The largest yield of unreported cases was identified through review of laboratory records; 13 of the 14 unreported cases were identified, of which eight were found only through this method. Timeliness of reporting varied between sites from a median of 7 days to a median of 38 days. The number of cases with delayed reporting varied from 5% to 53% between sites. Factors associated with delayed reporting included infectiousness, type of provider, diagnosing provider, and reporting source. CONCLUSIONS: Through a review of several different secondary data sources, few unreported TB cases were detected; however, timeliness of reporting was poor among the reported cases.

Transmission of Mycobacterium tuberculosis from medical waste.

CONTEXT: Washington State has a relatively low incidence rate of tuberculosis (TB) infection. However, from May to September 1997, 3 cases of pulmonary TB were reported among medical waste treatment workers at 1 facility in Washington. There is no previous documentation of Mycobacterium tuberculosis transmission as a result of processing medical waste. OBJECTIVE: To identify the source(s) of these 3 TB infections. DESIGN, SETTING, AND PARTICIPANTS: Interviews of the 3 infected patient-workers and their contacts, review of patient-worker medical records and the state TB registry, and collection of all multidrug-resistant TB (MDR-TB) isolates identified after January 1, 1995, from the facility's catchment area; DNA fingerprinting of all isolates; polymerase chain reaction and automated DNA sequencing to determine genetic mutations associated with drug resistance; and occupational safety and environmental evaluations of the facility. MAIN OUTCOME MEASURES: Previous exposures of patient-workers to TB; verification of patient-worker tuberculin skin test histories; identification of other cases of TB in the community and at the facility; drug susceptibility of patient-worker isolates; and potential for worker exposure to live M tuberculosis cultures. RESULTS: All 3 patient-workers were younger than 55 years, were born in the United States, and reported no known exposures to TB. We did not identify other TB cases. The 3 patient-workers' isolates had different DNA fingerprints. One of 10 MDR-TB catchment-area isolates matched an MDR-TB patient-worker isolate by DNA fingerprint pattern. DNA sequencing demonstrated the same rare mutation in these isolates. There was no evidence of personal contact between these 2 individuals. The laboratory that initially processed the matching isolate sent contaminated waste to the treatment facility. The facility accepted contaminated medical waste where it was shredded, blown, compacted, and finally deactivated. Equipment failures, insufficient employee training, and respiratory protective equipment inadequacies were identified at the facility. CONCLUSION: Processing contaminated medical waste resulted in transmission of M tuberculosis to at least 1 medical waste treatment facility worker. JAMA. 2000;284:1683-1688.

Using DNA fingerprinting to detect transmission of Mycobacterium tuberculosis among AIDS patients in two health-care facilities in Puerto Rico.

BACKGROUND: Fourteen cases of tuberculosis (TB) in Puerto Rico, diagnosed from April 1993 to April 1995, had the same DNA fingerprint, documenting disease caused by the same strain of Mycobacterium tuberculosis. The 14 cases were retrospectively investigated for epidemiologic links. METHODS: Records were reviewed and staffs of the TB program, hospital/clinic, and AIDS residential facilities were interviewed. RESULTS: Half of the AIDS cases were epidemiologically related, providing evidence of TB transmission in an emergency department, an AIDS inpatient ward, and an AIDS residential facility. DNA fingerprinting allowed detection of M tuberculosis transmission, but contact investigators could have documented it sooner. Factors contributing to transmission included delayed diagnosis, prolonged infectiousness, inadequate discharge planning and infection control procedures, and poor communication between health-care facilities. CONCLUSIONS: The numbers of AIDS residential facilities are increasing and must understand proper monitoring of TB patients and infection control measures that prevent transmissions.

Analysis of Mycobacterium tuberculosis transmission patterns in a homeless shelter outbreak.

SETTING: From July 1997 through May 1998, ten tuberculosis (TB) cases were reported among men in a Syracuse New York homeless shelter for men. OBJECTIVE AND DESIGN: Investigation to determine extent of, and prevent further, transmission of Mycobacterium tuberculosis. RESULTS: Epidemiologic and laboratory evidence suggests that eight of the ten cases were related. Seven cases had isolates with matching six-band IS6110 DNA fingerprints; the isolate from another case had a closely related fingerprint pattern and this case was considered to be caused by a variant of the same strain. Isolates from eight cases had identical spoligotypes. The source case had extensive cavitary disease and stayed at the shelter nightly, while symptomatic, for almost 8 months before diagnosis. A contact investigation was conducted among 257 shelter users and staff, 70% of whom had a positive tuberculin skin test, including 21 with documented skin test conversions. CONCLUSIONS: An outbreak of related TB cases in a high-risk setting was confirmed through the use of IS6110 DNA fingerprinting in conjunction with spoligotyping and epidemiologic evidence. Because of the high rate of infection in the homeless population, routine screening for TB and preventive therapy for eligible persons should be considered in shelters.

Extensive transmission of Mycobacterium tuberculosis from a child.

BACKGROUND AND METHODS: Young children rarely transmit tuberculosis. In July 1998, infectious tuberculosis was identified in a nine-year-old boy in North Dakota who was screened because extrapulmonary tuberculosis had been diagnosed in his female guardian. The child, who had come from the Republic of the Marshall Islands in 1996, had bilateral cavitary tuberculosis. Because he was the only known possible source for his female guardian's tuberculosis, an investigation of the child's contacts was undertaken. We identified family, school, day-care, and other social contacts and notified these people of their exposure. We asked the contacts to complete a questionnaire and performed tuberculin skin tests. RESULTS: Of the 276 contacts of the child whom we tested, 56 (20 percent) had a positive tuberculin skin test (induration of at least 10 mm), including 3 of the child's 4 household members, 16 of his 24 classroom contacts, 10 of 32 school-bus riders, and 9 of 61 day-care contacts. A total of 118 persons received preventive therapy, including 56 young children who were prescribed preventive therapy until skin tests performed at least 12 weeks after exposure were negative. The one additional case identified was in the twin brother of the nine-year-old patient. The twin was not considered infectious on the basis of a sputum smear that was negative on microscopical examination. CONCLUSIONS: This investigation showed that a young child can transmit Mycobacterium tuberculosis to a large number of contacts. Children with tuberculosis, especially cavitary or laryngeal tuberculosis, should be considered potentially infectious, and screening of their contacts for infection with M. tuberculosis or active tuberculosis may be required.

Cross-matching TB and AIDS registries: TB patients with HIV co-infection, United States, 1993-1994.

OBJECTIVES: Because of limited reporting of HIV status in case reports to the national tuberculosis (TB) surveillance system, the authors conducted this study to estimate the proportion of US TB cases with HIV co-infection and to describe demographic and clinical characteristics of co-infected patients. METHODS: The 50 states, New York City, and Puerto Rico submitted the results of cross-matches of TB registries and HIV-AIDS registries. The authors determined the number of TB cases reported for 1993-1994 that were listed in HIV-AIDS registries and analyzed data on demographic and clinical characteristics by match status. RESULTS: Of 49,938 TB cases reported for 1993-1994, 6863 (14%) were listed in AIDS or HIV registries. The proportions of TB-AIDS cases among TB cases varied by reporting area, from 0% to 31%. Anti-TB drug resistance was higher among TB-AIDS cases, particularly resistance to isoniazid and rifampin (multidrug resistance) and rifampin alone, In some areas with low proportions of multidrug-resistant TB cases, however, the difference in multidrug resistance between TB-AIDS patients and non-AIDS TB patients was not found. CONCLUSIONS: The proportion of TB cases with HIV co-infection, particularly in some areas, underscores the importance of the HIV-AIDS epidemic for the epidemiology of TB. Efforts to improve HIV testing as well as reporting of HIV status for TB patients should continue to ensure optimum management of coinfected patients, enhance surveillance activities, and promote judicious resource allocation and targeted prevention and control activities.

Spread of strain W, a highly drug-resistant strain of Mycobacterium tuberculosis, across the United States.

Strain W, a highly drug-resistant strain of Mycobacterium tuberculosis, was responsible for large nosocomial outbreaks in New York in the early 1990s. To describe the spread of strain W outside New York, we reviewed data from epidemiologic investigations, national tuberculosis surveillance, regional DNA fingerprint laboratories, and the Centers for Disease Control and Prevention Mycobacteriology Laboratory to identify potential cases of tuberculosis due to strain W. From January 1992 through February 1997, 23 cases were diagnosed in nine states and Puerto Rico; 8 were exposed to strain W in New York before their diagnosis; 4 of the 23 transmitted disease to 10 others. Eighty-six contacts of the 23 cases are presumed to be infected with strain W; 11 completed alternative preventive therapy. Strain W tuberculosis cases will occur throughout the United States as persons infected in New York move elsewhere. To help track and contain this strain, health departments should notify the Centers for Disease Control and Prevention of cases of tuberculosis resistant to isoniazid, rifampin, streptomycin, and kanamycin.

Immigration and tuberculosis among children on the United States-Mexico border, County of San Diego, California.

OBJECTIVE: To identify factors contributing to a 400% increase in tuberculosis among children in San Diego County, California, from 1985 to 1993. DESIGN: Review of medical records of reported cases in 1989, 1991, and 1993 and their source case. RESULTS: Of 192 children with tuberculosis, the largest increase was observed in children younger than 5 years old, of whom 77.4% were born in the United States, 67.8% had a foreign-born parent, 73.1% came from a non-English-speaking household, and 46.2% were known to visit Mexico. Of 28 source cases, 82.1% were born outside the United States, primarily in Mexico (67.9%). Resistance to at least one first-line antituberculous drug was identified in 27.5% of isolates from children and in 33.3% of isolates from source cases. CONCLUSIONS: The increase in tuberculosis and high level of drug-resistance among children born in the United States may be attributed to transmission outside of the United States or within the United States from household contacts born in countries in which tuberculosis is highly endemic.

Tuberculosis screening in private physicians' offices, Pennsylvania, 1996.

OBJECTIVE: To assess tuberculin skin testing practices of physicians after community-wide screening of 1400 children exposed to a pediatrician with active tuberculosis (TB). DESIGN: A self-administered questionnaire. SETTING: Medium-sized city in eastern Pennsylvania. PARTICIPANTS: Pediatricians and family practitioners seeing pediatric patients. MAIN OUTCOME MEASURES: Percentages of physicians who followed published recommendations for placement and reading of TB skin tests published by the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC). RESULTS: Questionnaires were completed by 60/80 (75%) physicians. The 60 physicians had practiced a mean of 17 years (range 3-38 years), and only one did not do TB skin testing for pediatric patients. The 59 physicians doing TB skin testing reported routinely tuberculin testing more than 900 children per month. Only 8/59 (14%) physicians followed published guidelines for placement and reading of tuberculin tests. Those physicians screened 158 (17%) of the pediatric patients undergoing TB skin testing in a typical month. CONCLUSION: In this community where a highly publicized TB case prompted massive pediatric screening, most physicians seeing children in private practice do not follow standard TB skin testing guidelines. Increased understanding of how private-practice physicians learn about and decide to use recommended standards are needed if tuberculin tests are to be correctly performed and TB appropriately diagnosed.

A train passenger with pulmonary tuberculosis: evidence of limited transmission during travel.

In January 1996, smear- and culture-positive tuberculosis (TB) was diagnosed for a 22-year-old black man after he had traveled on two U.S. passenger trains (29.1 hours) and a bus (5.5 hours) over 2 days. To determine if transmission had occurred, passengers and crew were notified of the potential exposure and instructed to undergo a tuberculin skin test (TST). Of the 240 persons who completed screening, 4 (2%) had a documented TST conversion (increase in induration of > or = 10 mm between successive TSTs), 11 (5%) had a single positive TST (> or = 10 mm), and 225 (94%) had a negative TST (< 10 mm). For two persons who underwent conversion, no other risk factors for a conversion were identified other than exposure to the ill passenger during train and/or bus travel. These findings support limited transmission of Mycobacterium tuberculosis from a potentially highly infectious passenger to other persons during extended train and bus travel.

Tuberculin skin test screening practices among US colleges and universities.

CONTEXT: Concern about transmission of Mycobacterium tuberculosis on college campuses has prompted some schools to institute tuberculin skin test screening of students, but this screening has never been evaluated. OBJECTIVE: To describe tuberculin skin test screening practices and results of screening in colleges and universities in the United States. DESIGN AND SETTING: Self-administered mail and telephone questionnaire in November and December 1995 to a stratified random sample of US 2-year and 4-year colleges and universities. MAIN OUTCOME MEASURES: Type of tuberculin screening required; types of schools requiring screening; number and rate of students with positive skin test results and/or diagnosed as having tuberculosis. RESULTS: Of the 3148 US colleges and universities, 624 (78%) of 796 schools surveyed responded. Overall, 378 schools (61%) required tuberculin screening; it was required for all new students (US residents and international students) in 161 (26%) of 624 schools, all new international students but not new US residents in 53 (8%), and students in specific academic programs in 294 (47%). Required screening was more likely in 4-year vs 2-year schools, schools that belonged to the American College Health Association vs nonmember schools, schools with immunization requirements vs schools without, and schools with a student health clinic vs those without (P<.001 for all). Public and private schools were equally likely to require screening (64% vs 62%; P=.21). In the 378 schools with screening requirements, tine or multiple puncture tests were accepted in 95 (25%); test results were recorded in millimeters of induration in 95 (25%); and 100 (27%) reported collecting results in a centralized registry or database. Of the 168 (27%) of 624 schools accepting only Mantoux skin tests and reporting results for school years 1992-1993 through 1995-1996, 3.1% of the 348 368 students screened had positive skin test results (median percentage positive, 0.8%). International students had a significantly higher case rate for active tuberculosis than US residents (35.2 vs 1.1 per 100000 students screened). CONCLUSIONS: Widespread tuberculin screening of students yielded a low prevalence of skin test reactors and few tuberculosis cases. To optimize the use of limited public health resources, tuberculin screening should target students at high risk for infection.