Charles L. Woodley

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.

Phenotypic Characterization of pncA Mutants of Mycobacterium tuberculosis

ABSTRACT We examined the correlation of mutations in the pyrazinamidase (PZase) gene (pncA) with the pyrazinamide (PZA) resistance phenotype with 60 Mycobacterium tuberculosis isolates. PZase activity was determined by the method of Wayne (L. G. Wayne, Am. Rev. Respir. Dis. 109:147–151, 1974), and the entirepncA nucleotide sequence, including the 74 bp upstream of the start codon, was determined. PZA susceptibility testing was performed by the method of proportions on modified Middlebrook and Cohn 7H10 medium. The PZA MICs were ≥100 μg/ml for 37 isolates, 34 of which had alterations in the pncA gene. These mutations included missense substitutions for 24 isolates, nonsense substitutions for 3 isolates, frameshifts by deletion for 4 isolates, a three-codon insertion for 1 isolate, and putative regulatory mutations for 2 isolates. Among 21 isolates for which PZA MICs were <100 μg/ml, 3 had the same mutation (Thr47→Ala) and 18 had the wild-type sequence. For the three Thr47→Ala mutants PZA MICs were 12.5 μg/ml by the method of proportions on 7H10 agar; two of these were resistant to 100 μg of PZA per ml and the third was resistant to 800 μg of PZA per ml by the BACTEC method. In all, 30 different pncA mutations were found among the 37 pncA mutants. No PZase activity was detected in 35 of 37 strains that were resistant to ≥100 μg of PZA per ml or in 34 of 37 pncA mutants. Reduced PZase activity was found in the three mutants with the Thr47→Ala mutation. This study demonstrates that mutations in the pncA gene may serve as a reliable indicator of resistance to ≥100 μg of PZA per ml.

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.

The molecular epidemiology of tuberculosis in New York City: the importance of nosocomial transmission and laboratory error

SETTING During the 1980s, New York City experienced a rapid increase of tuberculosis cases, more than 40% of which were human immunodeficiency virus (HIV)-associated. OBJECTIVE To better define the molecular epidemiology of tuberculosis in New York City. DESIGN We collected an isolate from every patient in New York City with a positive culture for Mycobacterium tuberculosis, including both incident and prevalent cases, in April 1991. Restriction fragment length polymorphism (RFLP) analysis using IS6110 was performed and the clinical, demographic, epidemiologic, and drug susceptibility patterns of patients were correlated with RFLP results. RESULTS Of 441 patients, 12 (3%) had laboratory, clinical, and RFLP evidence of falsely positive cultures. The remaining 429 patients had 252 distinct RFLP patterns. Patients with clustered 1-3 band isolates did not share demographic or drug susceptibility patterns. Eliminating these patients from the analysis, 344 patients remained, of whom 126 (37%) belonged to one of 31 clusters ranging in size from 2-17 patients (median cluster size = 3). Clustering was more common among patients with multidrug-resistant isolates (53%), African Americans (44%), and the homeless (49%), but was not associated with HIV infection or acquired immune deficiency syndrome (AIDS), Multidrug-resistance, being African American, and homelessness remained independently associated with clustering in multivariate analysis. Of 79 patients in clusters of > or = 4 patients, 25 (32%) had identifiable epidemiologic linkages; 17 (74%) of these patients, and 6% of all cases, were documented to have been nosocomially associated. CONCLUSION A small but non-negligible proportion (3%) of New York City patients had falsely positive cultures for M. tuberculosis as a result of laboratory error. More than one third of all patients and most patients with multidrug-resistance in April 1991 had clustered RFLP patterns, suggesting recent transmission of M. tuberculosis. Homelessness, multidrug-resistance, and being African American independently increased the risk of clustering. Most of the identified epidemiologic linkages and 6% of all cases resulted from transmission in hospitals.

Transmission of Tuberculosis in a Jail

Tuberculosis is a problem in correctional facilities throughout the United States. In 1996, 3.7% of all cases of tuberculosis nationwide occurred among residents of correctional facilities (1). Although in 1996 the incidence of new cases of active tuberculosis in the United States was 8.0 per 100 000 persons (1), many prison systems have reported rates of 200 per 100 000 persons and higher (2-10). Transmission of tuberculosis from prisons into surrounding communities has been documented (5), and correctional facilities may be important reservoirs of infection (11-13). One study concluded that a prison was potentially linked to 9% of a states tuberculosis cases during a 5-year period (5), and another study indicated that 24% of the tuberculosis cases in a county were associated with its jail (14). Prisons house convicts after sentencing, usually for terms exceeding 1 year (15). In contrast, jails receive prisoners immediately after arrest and generally house inmates awaiting trial or those sentenced to terms less than 1 year (16). Most jails are operated by cities or counties and hold inmates from the local community. In 1993, nearly 10 million inmates were admitted to local jails (16). Only 6% of jails house more than 50% of the nations jail inmates (16). Incarcerated populations have high rates of substance abuse, HIV infection, tuberculous infection, low socioeconomic status, and other risk factors associated with active tuberculosis (15, 17). At least 14 reports of outbreaks of tuberculosis in U.S. prisons have been published since 1985 (3, 5-7, 18, 19), but only two published reports have concerned outbreaks in jails (14, 20). Memphis, Tennessee, has the fifth largest jail in the United States (16). In 1996, the number of reported cases of tuberculosis diagnosed in inmates from the Memphis jail increased. This report summarizes the results of the ensuing investigation. Methods We reviewed the medical records of all persons in whom tuberculosis was diagnosed from 1 January 1995 through 31 December 1997 while they were incarcerated in the Memphis Criminal Justice Center (subsequently referred to as the jail). We obtained medical records from the jail, the Memphis/Shelby County Health Department Tuberculosis Clinic, and the hospital to which inmates were admitted for evaluations. For all inmates with active tuberculosis, computerized jail records were analyzed to determine dates of incarceration and cell locations for the 2 years before their diagnosis. A patient with a confirmed case of active tuberculosis had Mycobacterium tuberculosis isolated from a clinical specimen or met a clinical case definition [21]. Clinical cases met the following criteria: 1) a positive result on a tuberculin skin test, 2) signs and symptoms compatible with tuberculosis [for example, an abnormal, unstable chest radiograph or clinical evidence of current disease], and 3) treatment with at least two antituberculosis medications. Inmate cases were defined as patients in whom confirmed tuberculosis was diagnosed while they were incarcerated in the jail or within 3 weeks of transfer from the jail to another penal facility in the same city. Persons with culture-positive pulmonary tuberculosis were considered infectious from 6 weeks before collection of the first positive specimen until 2 weeks after initiation of appropriate therapy. A positive tuberculin skin test result was defined as at least 10 mm of induration within 48 to 72 hours after administration of five tuberculin units of tuberculin purified-protein derivative by the Mantoux method. Efforts were made to contact inmates who received a diagnosis of active tuberculosis after 1 January 1995, including those living in the community or incarcerated in other correctional facilities. A standardized questionnaire was administered to persons who could be located; the questionnaire asked about the patients lifestyle outside the jail before diagnosis of tuberculosis (for example, places frequented, behaviors, living and working situations, and exposure to persons with tuberculosis). Patients were also asked about incarceration history, possible contacts during incarceration, and activities while in jail. Jail administrators were interviewed and records were reviewed to determine baseline information on the jail population. The average age of inmates was calculated from a sample of 2552 inmates released or transferred from the jail on 12 randomly selected days in 1997. Inmate intake procedures at the jail were observed by two separate investigators on different days. Records from annual tuberculin skin test screening of jail staff, performed by the county health department on site at the jail, were reviewed. Medical records of staff with confirmed tuberculosis between 1 January 1995 and 31 December 1997 were also reviewed. The Tennessee Department of Health registry of all persons in Memphis reported with active tuberculosis from January 1995 through July 1997 was cross-matched with the list of persons incarcerated in the Memphis jail since 1979. Deoxyribonucleic acid fingerprinting was performed on all available M. tuberculosis isolates from culture-positive inmates and guards. Fingerprinting was also done for a sample of community cases, chosen by selecting every fifth isolate from a list of all culture-positive cases of tuberculosis in Memphis from 1 January 1995 through 1 September 1997, sorted by date of treatment initiation. If no isolate was available for the case selected, the next community case on the list was substituted. The Tennessee Department of Health Laboratory had processed 99.5% of all specimens from culture-positive cases reported from Memphis during the study period. Isolates were fingerprinted at the Centers for Disease Control and Prevention by IS-6110 restriction fragment length polymorphism analysis (22). Bivariate statistical analyses were performed by using chi-square tests calculated with Epi Info software (23). Results Jail Characteristics The jail housed approximately 2700 inmates at any time. More than 173 000 persons were admitted and discharged during the 3-year period. A mean of 159 inmates were admitted daily; the median length of stay was 1 day, and 8.3% of inmates stayed more than 30 days (Figure 1). Of persons admitted to the jail, 82% had previously been incarcerated there. The inmate population was 90% black and 90% male. The mean age of inmates was 32 years. Figure 1. Distribution of lengths of incarceration of inmates in the Memphis jail, 1995 to 1997. Inmates were housed on seven floors. Some units held up to 36 inmates in a single large room; other units had 18 two-person cells, and the 36 inmates intermingled for much of the day. Inmates lived and ate with members of the same unit, although inmates from different units had the potential to intermingle at visitation; during gym, chapel, infirmary, and legal-room (library) visits; and during transport outside the facility. For security reasons, inmates were moved frequently within the jail. Jail Screening Procedures Routine medical screening at intake to the jail consisted of two questions: Are you seeing a doctor for anything? and Are you taking any medications? This screening process took approximately 15 seconds per inmate. If the screening procedure did not reveal an obvious history of tuberculosis, the inmate was admitted into the general jail population. Jail protocol called for tuberculin skin test screening of all inmates still in the facility 10 days after admission. Inmates with evidence of possible tuberculosis on initial screening, in subsequent medical visits, or on tuberculin skin test screening were transported to a hospital emergency department or the county health department tuberculosis clinic for chest radiographs and evaluation. Those thought to have possible active tuberculosis were then transferred to a local hospital for isolation and completion of evaluation. Inmates given a diagnosis of active tuberculosis were returned to the jail after three sputum smears were negative for acid-fast bacteria. The jail does not have radiography facilities or negative-pressure isolation rooms. From 1995 through 1997, 173 815 inmates were admitted to the jail; 13 239 (7.8%) inmates underwent tuberculin skin testing. These inmates represented 36% of the target population of inmates incarcerated for more than 10 days. Of tuberculin skin tests placed, 10 110 (74%) were read; 431 (4.3%) of these were reported as yielding positive results. Inmates who volunteer are counseled about and tested for HIV at the jail by county health department representatives. Of the inmates admitted to the jail during this 3-year period, less than 1% were screened for HIV there. Of 1622 HIV tests performed, 26 (1.6%) had positive results. Inmate Tuberculosis Cases Active tuberculosis was diagnosed in 38 jail inmates from 1 January 1995 through 31 December 1997 (Figure 2). Ten cases were diagnosed in 1995, 19 in 1996, and 9 in 1997. The calculated incidence of active tuberculosis diagnosed in inmates who were physically in the jail was 274 per 100 000 during this 3-year period. Figure 2. Cases of active tuberculosis disease diagnosed in guards ( top ) and inmates ( bottom ) from the Memphis jail, 1 January 1995 through 31 December 1997, by quarter in which disease was diagnosed. Inmates with tuberculosis had been in the jail a median of 15 times before diagnosis. The median length of continuous incarceration before the diagnosis of tuberculosis was 138 days (range, 10 to 800 days) (Table). By comparison, the median length of incarceration for all inmates in the jail is 1 day (mean, 13.4 days). Ten (26%) of the inmates with active tuberculosis were given the diagnosis during evaluation for symptoms, 25 (66%) were discovered as a result of evaluation of a positive tuberculin skin test result, and 3 (8%) were found during contact investigations of other cases. Table. Characteristics of the 38 Inmates in Whom Tub

Evaluation of infection control measures in preventing the nosocomial transmission of multidrug-resistant Mycobacterium tuberculosis in a New York City hospital.

OBJECTIVE To evaluate the efficacy of Centers for Disease Control and Prevention (CDC)-recommended infection control measures implemented in response to an outbreak of multidrug-resistant (MDR) tuberculosis (TB). DESIGN Retrospective cohort studies of acquired immunodeficiency syndrome (AIDS) patients and healthcare workers. The study period (January 1989 through September 1992) was divided into period I, before changes in infection control; period II, after aggressive use of administrative controls (eg, rapid placement of TB patients or suspected TB patients in single-patient rooms); and period III, while engineering changes were made (eg, improving ventilation in TB isolation rooms). SETTING A New York City hospital that was the site of one of the first reported outbreaks of MDR-TB among AIDS patients in the United States. PARTICIPANTS All AIDS patients admitted during periods I and II. Healthcare workers on nine inpatient units with TB patients and six without TB patients. RESULTS The epidemic (38 patients) waned during period II and only one MDR-TB patient presented during period III. The MDR-TB attack rate among AIDS patients hospitalized on the same ward on the same days as an infectious MDR-TB patient was 8.8% (19 of 216) during period I, decreasing to 2.6% (5 of 193; P = 0.01) during period II. In a small group of healthcare workers with tuberculin skin test data, conversions during periods II through III were higher on wards with than without TB patients (5 of 29 versus 0 of 15; P = 0.15), although the difference was not statistically significant. CONCLUSIONS Transmission of MDR-TB among AIDS patients decreased markedly after enforcement of readily implementable administrative measures, ending the outbreak. However, tuberculin skin-test conversions among healthcare workers may not have been prevented by these measures. CDC guidelines for prevention of nosocomial transmission of TB should be implemented fully at all US hospitals.

Molecular and conventional epidemiology of Mycobacterium tuberculosis in Botswana : a population-based prospective study of 301 pulmonary tuberculosis patients

ABSTRACT Little is known about patterns of tuberculosis (TB) transmission among populations in developing countries with high rates of TB and human immunodeficiency virus (HIV) infection. To examine patterns of TB transmission in such a setting, we performed a population-based DNA fingerprinting study among TB patients in Botswana. Between January 1997 and July 1998, TB patients from four communities in Botswana were interviewed and offered HIV testing. Their Mycobacterium tuberculosis isolates underwent DNA fingerprinting using IS6110 restriction fragment length polymorphism, and those with matching fingerprints were reinterviewed. DNA fingerprints with >5 bands were considered clustered if they were either identical or differed by at most one band, while DNA fingerprints with ≤5 bands were considered clustered only if they were identical. TB isolates of 125 (42%) of the 301 patients with completed interviews and DNA fingerprints fell into 20 different clusters of 2 to 16 patients. HIV status was not associated with clustering. Prior imprisonment was the only statistically significant risk factor for clustering (risk ratio, 1.5; 95% confidence interval, 1.1 to 2.0). In three communities where the majority of eligible patients were enrolled, 26 (11%) of 243 patients overall and 26 (25%) of 104 clustered patients shared both a DNA fingerprint and strong antecedent epidemiologic link. Most of the increasing TB burden in Botswana may be attributable to reactivation of latent infection, but steps should be taken to control ongoing transmission in congregate settings. DNA fingerprinting helps determine loci of TB transmission in the community.

Rapid, amplification-based fingerprinting of Mycobacterium tuberculosis.

Insertion element IS6110 occurs in multiple copies throughout the Mycobacterium tuberculosis genome, and the variability of its insertion sites is the basis for the IS6110 restriction fragment length polymorphism (RFLP) method for typing. We describe a novel gene amplification method to assess the variability of the location of IS6110. A unilateral-nested polymerase chain reaction and hybridization procedure was used to measure the variability in the distances between IS6110 elements and copies of a major polymorphic tandem repeat sequence of M. tuberculosis. The pattern of amplicons produced could be used to cluster epidemiologically related strains of M. tuberculosis into groups which correlated with the groups formed using IS6110-RFLP typing. Reliable patterns can be generated directly from sputum specimens as well as from M. tuberculosis cultures. We designated the novel method as IS6110-ampliprinting.

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.

Effect of Temperature on the Rate of the Transparent to Opaque Colony Type Transition in Mycobacterium avium

The results of drug susceptibility tests were found to be affected by changes that occur spontaneously in populations of Mycobacterium avium maintained in the laboratory. Because the transparent colony type variant was resistant to antituberculosis chemotherapeutic agents and the opaque colony type variant was usually susceptible to these agents, the transition of transparent to opaque colony type was investigated. The rate of the transition was found to be temperature dependent and, in agreement with a previous report, was found to be about 10−4 to 10−5 per generation at 37 C. Reversion was found to occur at a rate of 10−6 to 10−7 at 37 C. The mutation rate from susceptibility to resistance to rifampin, kanamycin, and erythromycin was about 10−8 to 10−9 mutations per bacterium per generation. Judged from our data, the high rate of the transparent to opaque variation was not caused either by mutator effects or by the occurrence of extrachromosomal genes in these bacteria, but could have been due to selective mechanisms still incompletely understood.