Mycobacterium malmoense infections in the United States, January 1993 through June 1995.

Mycobacterium malmoense is a nontuberculous mycobacterium rarely encountered in the United States. However, isolations of M. malmoense from 73 patients (11 in 1992, 35 in 1993, and 27 in 1994) were reported to the Centers for Disease Control and Prevention. We contacted state mycobacteriology laboratories and health care providers of patients whose M. malmoense isolations were reported from January 1993 through June 1995. To assign disease status for these patients, we used the criteria of the American Thoracic Society. Of 60 evaluable patients with disease status, only six (10%) had disease due to M. malmoense (five adults with pulmonary disease and one child with cervical lymphadenitis). We conclude that the number of patients with disease due to M. malmoense remains low. Increased isolation of this species may be due to the increased use of more sensitive and specific laboratory methods. For surveillance purposes, multiple M. malmoense isolates and age of younger than 10 years appear to be the best predictors for M. malmoense disease.

Pseudo-outbreak of septicemia due to rapidly growing mycobacteria associated with extrinsic contamination of culture supplement.

Between April and December 1994, 23 blood cultures from human immunodeficiency virus-infected patients grew rapidly growing mycobacteria suspected to be Mycobacterium chelonae at a hospital in New Jersey. The isolates were later identified as M. abscessus. Several bacterial species, including M. abscessus, were cultured from an opened multidose supplement vial (BBL Septi-Chek AFB Supplement) that had been used for mycobacterial blood cultures. The M. abscessus isolates from case patients and the supplement vial had identical multilocus enzyme electrophoresis and antimicrobial susceptibility patterns. Finding a contaminated vial of supplement, together with the lack of a distinct syndrome in case patients, was consistent with a pseudo-outbreak.

Descriptive profile of tuberculin skin testing programs and laboratory-acquired tuberculosis infections in public health laboratories.

The increase in numbers of cases of tuberculosis in the United States has placed greater demands on mycobacteriology laboratory workers to produce rapid and accurate results. The greater number of specimens generated by the increased emphasis on detecting the disease has placed these workers at greater risk of laboratory-acquired infection. We surveyed 56 state and territorial public health laboratories to determine the status of existing tuberculin skin testing (TST) programs and to evaluate the frequency of probable laboratory-acquired tuberculosis for each responding mycobacteriology laboratory. Probable laboratory-acquired infections were determined by each laboratory's evaluation of occupational positions, duties, and employee histories and review of medical records. Two-step TST for new employees was routinely practiced in only 33% of responding laboratories, and mycobacteriology laboratorians were found to be most frequently screened when they were compared to employees of other departments. Of 49 (88%) responding laboratories, 13 reported that 21 employees were TST converters from 1990 to 1994. Seven of these 21 employees were documented to have laboratory-acquired infections based on evaluations by their respective laboratories. Based on Centers for Disease Control and Prevention guidelines, converters are categorized on the basis of both a change in the size of the zone of induration and the age of the person being tested. By the definitions in the guidelines, 14 mycobacteriologists were identified as recent converters, 7 of whom were > or = 35 years of age and 4 of whom were exposed in the laboratory within a 2-year period. Inadequate isolation procedures, the high volume of specimen handling, and faulty ventilation accounted for these laboratory-associated infections. These results suggest that more frequent periodic evaluations based on documented TST conversions for workers in mycobacterial laboratories should be performed, since this population is at increased risk of becoming infected with Mycobacterium tuberculosis. Although general assessments are necessary to accurately and effectively evaluate the risk of tuberculosis transmission, they are especially important for those working in high-risk areas within a public health laboratory.

Biosafety in the clinical mycobacteriology laboratory.

This article presents an expanded agent summary statement for laboratorians working with Mycobacterium tuberculosis. It focuses on reducing the serious risk of infection in clinical laboratories that process specimens from tuberculosis patients or that work with purified cultures of tubercle bacilli. Administrative and engineering controls, practices and procedures, and personal protective equipment are discussed. Guidelines for packaging specimens for transfer to another laboratory also are presented.

Changing practices in mycobacteriology: a follow-up survey of state and territorial public health laboratories.

The resurgence of tuberculosis, which includes an increase in the isolation of multidrug-resistant strains of Mycobacterium tuberculosis, emphasizes the need for more rapid laboratory testing for identification of the etiological agent of the disease. In December 1991, state and territorial public health laboratories were surveyed to determine the methods that they were using for testing and reporting of M. tuberculosis. A follow-up survey was conducted in June 1994 to measure changes in the testing and reporting practices that had occurred as a result of efforts focused on the disease and on laboratory improvement. Completed questionnaires were received from 51 of 55 laboratories. Comparative data indicate that the proportion of laboratories reporting testing results within the number of days recommended by the Centers for Disease Control and Prevention has increased. Starting from the time at which the laboratory receives the specimen, the proportion of laboratories reporting the results of microscopic smear examination within the recommended 24 h has increased from 52.1 to 77.6%; the proportion reporting isolation and identification within 21 days has increased from 22.1 to 72.9%; and the proportion reporting results of isolation, identification, and drug susceptibility testing within 28 days has increased from 16.7 to 48.9%. Use of the recommended rapid testing methods has also increased: the proportion of laboratories using fluorescence staining for acid-fast microscopy has increased from 71.4 to 85.7%, the proportion using BACTEC for primary culture has increased from 27.1 to 79.6%, the proportion using rapid methods for M. tuberculosis identification has increased from 74.5 to 100.0%, and the proportion using BACTEC for primary drug susceptibility testing has increased from 26.2 to 73.3%. By implementing the recommended methods for M. tuberculosis testing and reporting, state and territorial public health laboratories are now able to transmit results to physicians more rapidly.

Semantide- and chemotaxonomy-based analyses of some problematic phenotypic clusters of slowly growing mycobacteria, a cooperative study of the International Working Group on Mycobacterial Taxonomy.

During previous cooperative numerical taxonomic studies of slowly growing mycobacteria, the International Working Group on Mycobacterial Taxonomy described a number of strains whose taxonomic status was ambiguous. A new study of DNA, RNA, and proteins from 66 of these organisms was performed to correlate their properties with phenotypic clustering behavior; the results of this study permitted 51 of the strains studied to be assigned to known species. The methods used to characterize the semantides included nucleotide sequencing and assessment of levels of semantide relatedness by affinity binding techniques, including whole DNA-DNA hybridization, probe hybridization, and antibody binding. There was good overall agreement between the phenotypic and chemotaxonomic clusters and the groups of organisms identified by semantide analyses. Our results supported the conclusion that we should continue to rely on polyphasic taxonomy to provide satisfactory systematic resolution of members of the genus Mycobacterium. We identified no single 16S rRNA interstrain nucleotide sequence difference value that unequivocally defined species boundaries. DNA-DNA hybridization remains the gold standard, but common resources are needed to permit DNA-DNA hybridization analyses to be made available to laboratories that are not prepared to use this technology. One of the large novel clusters which we studied corresponds to the recently described species Mycobacterium interjectum, a pathogen that resembles the nonpathogen Mycobacterium gordonae phenotypically. We also identified strains that appear to represent ribovars of Mycobacterium intracellulare which do not react with the commercial diagnostic probes that are currently used for identification of this species. Other branches or clusters consisted of too few strains to permit a decision about their taxonomic status to be made.

Diagnostic mycobacteriology laboratory practices.

The resurgence of tuberculosis has forced clinical laboratories to improve the methods used for detection of M. tuberculosis. Current recommendations for diagnostic laboratory performance [7] include (1) daily processing of specimens (i.e., handling these specimens in the same way that all other specimens sent to the laboratory are handled); (2) inoculation of liquid media (e.g., BACTEC) for the primary culture; (3) use of nucleic acid probes or the NAP test for identifying isolates as M. tuberculosis as soon as possible; (4) determining drug susceptibility with use of liquid media; and (5) reporting results of each step to physicians in a timely manner. The immediate goals are to report identification of M. tuberculosis within 10-14 days of receipt of the specimen and to report drug susceptibilities within 15-30 days. This can be done if current technologies are fully utilized. The amplification-based systems for the identification of M. tuberculosis and the luciferase-based systems for rapid determination of drug susceptibilities should help further shorten turn-around times. The results to date demonstrate that these systems are feasible, although they must be reduced to formats that can be used routinely in clinical laboratories. The gene-amplification systems may be the most promising, and they are nearing commercial availability. If the assays function as well during routine use as they have during clinical trials, a clinical laboratory may soon be able to report confirmed M. tuberculosis infection to the physician within hours of receiving a specimen, instead of within the typical period of 2-4 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergence of Buruli ulcer disease in the Daloa region of Cote d'Ivoire.

Recent reports have suggested increases in Buruli ulcer (BU), an infection caused by Mycobacterium ulcerans in west Africa. In 1991, we conducted surveillance for BU in a rural area of Cote d'Ivoire and identified 312 cases of active or healed ulceration. A case-control study was then performed to investigate risk factors for this infection. The rate of illness did not appear to differ between males and females (5.2% versus 7.5%; P = 0.11). The highest rate of illness was seen in the 10-14-year-old age group (143 cases per 1,000 population). New cases increased more than three-fold between 1987 and 1991, and local prevalence of BU was as high as 16.3%. Twenty-six percent of persons with healed ulcers had chronic functional disability. Participation in farming activities near the main river in the region was identified in the case-control study as a risk factor for infection (odds ratio [OR] for each 10-min decrease in walking distance between the fields and the river = 1.52, 95% confidence interval [CI] 1.01, 2.28, P = 0.046). Wearing long pants was protective (OR 0.20, 95% CI 0.06, 0.62, P < 0.005). We conclude that the incidence of BU is increasing rapidly in Cote d'Ivoire. Specific causes of this increase were not identified, but wearing protective clothing appeared to decrease the risk of disease.

Mycobacterial taxonomy.

The minimal standards for including a species in the genus Mycobacterium are i) acid-alcohol fastness, ii) the presence of mycolic acids containing 60-90 carbon atoms which are cleaved to C22 to C26 fatty acid methyl esters by pyrolysis, and iii) a guanine + cytosine content of the DNA of 61 to 71 mol %. Currently, there are 71 recognized or proposed species of Mycobacterium which can be divided into two main groups based on growth rate. The slowly growing species require > 7 days to form visible colonies on solid media while the rapidly growing species require < 7 days. Slowly growing species are often pathogenic for humans or animals while rapidly growing species are usually considered nonpathogenic for humans, although important exceptions exist. The taxonomic and diagnostic characteristics of medically important species and of newly described species of the Mycobacterium genus are reviewed.

Risk factors for transmission of Mycobacterium tuberculosis in a primary school outbreak: lack of racial difference in susceptibility to infection.

Recent data have suggested that there are racial differences in the susceptibility to infection by Mycobacterium tuberculosis. An opportunity to test this suggestion was afforded by an outbreak of tuberculosis in a racially mixed elementary school in St. Louis County, Missouri. A physical education teacher was discovered to have cavitary pulmonary tuberculosis. Of 343 students in the school, 176 (51 percent) were found to be tuberculin skin test positive (> or = 5 mm induration by Mantoux method); 32 children had abnormal chest radiographs. More frequent contact with the physical education teacher was associated with infection (p < 0.001). Black children were no more likely to be infected than were white children (relative risk (RR) = 0.98, 95% confidence interval (CI) 0.78-1.22). However, black children who were tuberculin positive had larger skin reactions than did white children (mean, 18.9 vs. 16.6 mm, p < 0.001) and were more likely to have abnormal chest radiographs (RR = 2.76, 95% CI 1.44-5.27). Among tuberculin-positive children, low body mass index (less than 10th percentile) was associated with active disease (RR = 2.90, 95% CI 1.45-5.80). The analysis of race was unchanged after controlling for sex, body build, and level of contact with the physical education teacher. Widespread tuberculous infection resulted from contact with a highly infectious staff person. Thin body build was a risk factor for active disease. Black children were no more susceptible to infection than were white children, although they more commonly developed radiographic evidence of active disease.

Clinical and epidemiologic characteristics of Mycobacterium haemophilum, an emerging pathogen in immunocompromised patients.

OBJECTIVE: To describe 13 infections caused by Mycobacterium haemophilum. DESIGN: Identification of patients by microbiologic record review, followed by medical record review and a case-control study. SETTING: Seven metropolitan hospitals in New York. PATIENTS: All patients with M. haemophilum infections diagnosed between January 1989 and September 1991 and followed through September 1992. Surviving patients were enrolled in the case-control study. RESULTS: Infection with M. haemophilum causes disseminated cutaneous lesions, bacteremia, and diseases of the bones, joints, lymphatics, and the lungs. Improper culture techniques may delay laboratory diagnosis, and isolates may be identified incorrectly as other mycobacterial species. Persons with profound deficits in cell-mediated immunity have an increased risk for infection. These include persons with human immunodeficiency virus infection or lymphoma and those receiving medication to treat immunosuppression after organ transplant. Various antimycobacterial regimens have been used with apparent success to treat M. haemophilum infection. However, standards for defining antimicrobial susceptibility to the organism do not exist. CONCLUSIONS: Clinicians should consider this pathogen when evaluating an immunocompromised patient with cutaneous ulcerating lesions, joint effusions, or osteomyelitis. Microbiologists must be familiar with the fastidious growth requirements of this organism and screen appropriate specimens for mycobacteria using an acid-fast stain. If acid-fast bacilli are seen, M. haemophilum should be considered as the infecting organism as well as other mycobacteria, and appropriate media and incubation conditions should be used.

A nosocomial pseudo-outbreak of Mycobacterium xenopi due to a contaminated potable water supply: lessons in prevention.

OBJECTIVES: To determine risk factors for Mycobacterium xenopi isolation in patients following a pseudo-outbreak of infection with the organism. DESIGN: Retrospective cohort analysis of mycobacteriology laboratory specimen records and frequency-matched case-control study of hospital patients. SETTING: General community hospital. PATIENTS: For the case-control study, 13 case patients and 39 randomly selected controls with mycobacterial cultures negative for M xenopi, frequency matched by specimen source, whose specimens were submitted from June 1990 through June 1991. RESULTS: Between June 1990 and June 1991, M xenopi was isolated from 13 clinical specimens processed at a midwestern hospital, including sputum (n = 6), bronchial washings (2), urine (4), and stool (1). None of the patients with M xenopi-positive specimens had apparent mycobacterial disease, although five received antituberculosis drug therapy for a range of one to six months. Specimens collected in a nonsterile manner were more likely to grow the organism than those collected aseptically (3.1% versus 0, relative risk = infinity, P = 0.003). M xenopi isolation was attributed to exposure of clinical specimens to tap water, including rinsing of bronchoscopes with tap water after disinfection, irrigation with tap water during colonoscopy, gargling with tap water before sputum collection, and collecting urine in recently rinsed bedpans. M xenopi was isolated from tap water in 20 of 24 patient rooms tested, the endoscopy suite, and the central hot water mixing tank, but not from water in the microbiology laboratory. The pseudo-outbreak occurred following a decrease in the hot water temperature from 130 degrees F to 120 degrees F in 1989. CONCLUSIONS: Maintenance of a higher water temperature and improved specimen collection protocols and instrument disinfection procedures probably would have prevented this pseudo-outbreak.

Serovar determination and molecular taxonomic correlation in Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum: a cooperative study of the International Working Group on Mycobacterial Taxonomy.

A cooperative study was conducted by the International Working Group on Mycobacterial Taxonomy to correlate the agglutination serovar designations of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum strains with the species ascriptions of these organisms according to molecular criteria and cultural properties and to assess the reproducibility of serovar determinations for a set of 63 reference strains of these species. Among the molecular criteria, the level of agreement between results obtained with nucleic acid probes and T-catalase serology results was 94% for strains of M. avium and M. intracellulare. Nucleic acid probes were not available for M. scrofulaceum, but none of the 10 strains ascribed to this species on the basis of catalase serology data reacted with a nucleic acid probe for M. avium or M. intracellulare. Ascription to a species on the basis of mycolic acid high-performance liquid chromatography patterns was in agreement with catalase serology results in 86% of the cases examined. Most strains belonging to serovars 1 through 6 and 8 through 11 were identified by molecular criteria as M. avium, most strains belonging to serovars 7, 12 through 20, 23, and 25 were identified as M. intracellulare, and most strains belonging to serovars 41 through 43 were identified as M. scrofulaceum, in agreement with common current practice. Evidence for assigning serovar 27 to M. scrofulaceum was obtained. However, two strains of a given serovar may, on occasion, be placed in different species. The dominant species assignments for strains belonging to serovars 21, 24, 26, and 28 remain unresolved.(ABSTRACT TRUNCATED AT 250 WORDS)

Current practices in mycobacteriology: results of a survey of state public health laboratories.

Fifty-six state and territorial public health laboratories were surveyed to determine whether currently available rapid methods for the identification and drug susceptibility testing of Mycobacterium tuberculosis were being performed. Forty (71%) laboratories use fluorochrome rather than conventional basic fuchsin stains for screening clinical specimens for acid-fast bacilli. Of the 55 laboratories that routinely culture for mycobacteria, 16 (29%) use the more rapid radiometric methods. Species identification of isolates is done by biochemical tests in 13 (23%) laboratories; 40 (72%) use nucleic acid probes, high-performance liquid chromatography, or the BACTEC p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) test (rapid tests); 3 laboratories do not perform species identification. Drug susceptibility testing is performed with solid media by 36 of 45 (80%) laboratories, while the more rapid radiometric methods are used by 9 (20%) laboratories. Compared with the laboratories that use conventional methods, laboratories that use rapid methods report results more quickly: for species identification, 43 days (conventional) versus 22 days (rapid); for drug susceptibility testing, 44 days (conventional) versus 31 days (rapid) from specimen processing. Rapid technologies for microscopy and species identification are being used by many, but not all, state and territorial public health laboratories; however, most laboratories do not use the more rapid radiometric methods for routine culture or drug susceptibility testing of mycobacteria. Implementation of such rapid technologies can shorten turnaround times for the laboratory diagnosis of tuberculosis and recognition of drug resistance.

Evaluation of the clinical usefulness of mycobacterial skin test antigens in adults with pulmonary mycobacterioses.

A double-blind, multicenter study was conducted to evaluate the usefulness of mycobacterial skin test antigens for the specific diagnosis of adult pulmonary mycobacterial disease. The skin test antigens used were PPD-T (M. bovis) and PPD-B (M. intracellulare), made bioequivalent to 5 TU PPD-S through bioassay in human subjects. Of the 192 adults (18 yr of age or older), those with disease caused by M. tuberculosis (MTB) had significantly larger reactions to PPD-T than did those with disease caused by nontuberculous mycobacteria (NTM) or those with negative culture results (NEG)(13.41 mm versus 4.87 and 4.96 mm, respectively, p less than 0.001). The mean induration to PPD-B in NTM was not different from that in MTB or NEG. Defining a "positive" to be greater than or equal to 10 mm induration and a size difference of greater than or equal to 3 mm between PPD-T and PPD-B, the sensitivity, specificity, and positive predictive value (PPV) for PPD-T in diagnosing MTB versus NTM was 29, 90, and 75%. Corresponding values for PPD-B and NTM disease were 70, 61, and 64%. Dual testing was less useful in distinguishing disease caused by any of the mycobacteria from NEG. Although the sensitivity of PPD-B, made bioequivalent to PPD-S, was high, the specificity and PPV were low. We conclude that this preparation of PPD-B is no more useful in distinguishing adult pulmonary disease caused by NTM than is PPD-T alone.

Fourth report of the cooperative, open-ended study of slowly growing mycobacteria by the International Working Group on Mycobacterial Taxonomy.

The open-ended study of the International Working Group on Mycobacterial Taxonomy is an ongoing project to characterize slowly growing strains of mycobacteria that do not belong to well-established or thoroughly characterized species. In this fourth report we describe two numerical taxonomic clusters that represent subspecies or biovars of Mycobacterium simiae, one cluster that encompasses the erstwhile type strain of the presently invalid species "Mycobacterium paraffinicum," one cluster that is phenotypically very similar to Mycobacterium avium and Mycobacterium intracellulare but may be a separate genospecies, one cluster that appears to be phenotypically distinct from M. avium but reacts with a nucleic acid probe specific for M. avium, and three tentatively defined clusters in proximity to a cluster that encompasses the type strain of Mycobacterium malmoense. Of special practical interest is the fact that one of the latter three clusters is composed of clinically significant scotochromogenic bacteria that can be misidentified as the nonpathogenic organism Mycobacterium gordonae if insufficient biochemical tests are performed.

Geographic distribution, frequency, and specimen source of Mycobacterium avium complex serotypes isolated from patients with acquired immunodeficiency syndrome.

Isolates of Mycobacterium avium complex from 727 patients with acquired immunodeficiency syndrome (AIDS) were submitted by medical centers across the United States to the Centers for Disease Control for serotyping. We were able to type 630 (87%) of these isolates by our seroagglutination procedure. Almost all typeable isolates were M. avium (serotypes 1 to 6 and 8 to 11). Blood was the major specimen source for both M. avium and the nontypeable isolates. M. intracellulare serotypes made up only 3% of all isolates from AIDS patients, with sputum being the major specimen source. More than 50% of the isolates originated from either New York or California, with serotype 4 being isolated most frequently in New York and serotype 8 appearing most frequently in California. AIDS patients in Los Angeles had a significantly higher isolation frequency for serotype 8 and a significantly lower one for serotype 4 in comparison with patients in either San Francisco or New York City.