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Biomedical subjects

N G Warren

Publications and source records attributed to N G Warren.

17 recordsLinked to original sources
PubMed1999

Cutaneous phaeohyphomycosis due to Cladophialophora bantiana.

We present a case of cutaneous infection due to Cladophialophora bantiana, an agent of phaeohyphomycosis. The patient developed a nodule with pustule formation on the dorsum of the left hand; no trauma was reported. The lesion was successfully treated with itraconazole and surgical excision. Histopathologically, there was a blastomycosis-like tissue reaction pattern. Pigmented organisms were readily identified in tissue sections, and the cultural characteristics were those of Cladophialophora bantiana. This organism, known primarily for intracerebral involvement, can rarely produce cutaneous and subcutaneous infection. Immunosuppression should be suspected but is not always clinically apparent, as was demonstrated by our case.

Aged↗
PubMed1997

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.

Humans↗
PubMed1996

Taxonomy and introduction.

Fungi and the diseases that they produce have become an important part of patient care and management. Identification of these organisms can be difficult because of the need to know and discern fungal morphology and structure. This article reviews mycologic terms, describes and defines fungal structures, discusses fungal isolation techniques, and suggests steps for identification approaches.

Classification↗
PubMed1996

Actinomycosis, nocardiosis, and actinomycetoma.

Cases of actinomycosis, nocardiosis, and actinomycetoma are seen infrequently but consistently in the United States. When they are found, diagnosis can be difficult because of their resemblance to other bacterial, mycobacterial, and fungal infections. This article reviews the clinical presentation, therapy, and laboratory diagnosis of these actinomycetales.

Actinomyces↗
PubMed1996

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.

Bacterial Proteins↗
PubMed1996

Clinical mycobacteriology. Activities and recommendations by the association of state and territorial public health laboratory directors.

By using the assessment, policy development, and assurance model to describe the functions of public health, the Association of State and Territorial Public Health Laboratory Directors (ASTPHLD) is shown to be responding to the laboratory aspects of tuberculosis detection, prevention, and control. The many activities described illustrate the value of public-private partnerships in addressing population-based, public health threats. The network of state and territorial public health laboratories, through voluntary involvement in ASTPHLD, provides an important resource to the scientific, educational, and policy-making community.

Bacteriology↗
PubMed1995

Effect of transportation and acid neutralization on recovery of mycobacteria from processed specimens.

Because of the increasing incidence of tuberculosis, more rapid detection of mycobacteria has become an important issue. Realizing that not every clinical laboratory has a rapid detection system for growing mycobacteria, this study was conducted to examine the feasibility of submitting sediments of processed specimens to a reference laboratory for further testing in a radiometric system. Using N-acetyl-L-cysteine-NaOH solution, 247 respiratory specimens were processed at a diagnostic laboratory. Half of each sediment was cultured on conventional media. The remainder was kept at 4 degrees C for a period of up to 1 week before transportation to a reference laboratory for culture by BACTEC system. Both laboratories recovered 25 organisms: 15 as Mycobacterium tuberculosis (MT) and 10 as M avium complex (MAC). Additionally, mycobacteria (MT[3], MAC[6], M gordonae [4], and M fortuitum [1]) were recovered from 14 specimens by the diagnostic laboratory that were not grown by the reference laboratory. These results indicate a significant decrease in viability of mycobacteria after processing of the specimens. Acid neutralization of the digested respiratory sediments significantly improved the recovery rate of mycobacteria even after 2 days of delay in culture. This preliminary work suggests that more extensive studies will provide useful information to delineate approaches to submitting neutralized sediments for mycobacterial cultures.

Humans↗
PubMed1993

Strains of Mycobacterium terrae complex which react with DNA probes for M. tuberculosis complex.

Following a recent report that two isolates of Mycobacterium terrae complex had given positive reactions with M. tuberculosis complex DNA probes, a joint study was undertaken to determine the extent of these findings in the clinical culture collection holdings of two state health laboratories. A total of 117 M. terrae complex strains (identified by standard biochemical methods) were subjected to M. tuberculosis complex probe testing with the two then-available kits (from Syngene, Inc., and Gen-Probe, Inc.). In addition to the two original isolates first reported, two further M. terrae complex isolates were found to react with the M. tuberculosis complex probes. Two modifications of the Accuprobe (Gen-Probe, Inc.) test method were evaluated. Extension of the selection time to 8 min was the most convenient modification and rendered the M. terrae complex isolates negative when tested with the Accuprobe M. tuberculosis complex probe. However, the effects of increased selection time on the overall sensitivity of the M. tuberculosis complex probe require further study.

DNA Probes↗
PubMed1990

Use of Gen-Probe and Bactec for rapid isolation and identification of mycobacteria. Correlation of probe results with growth index.

Gen-Probe culture confirmation tests (Gen-Probe, San Diego, CA) for Mycobacterium tuberculosis complex and Mycobacterium avium complex were performed on 276 mycobacterial isolates. All 138 M. tuberculosis complex isolates and 79 of 80 M. avium complex isolates were identified correctly. No falsely positive test results were obtained; 58 nontuberculous mycobacteria other than M. avium complex were negative by Gen-Probe. In a second phase of testing, Gen-Probe tests were performed using concentrates from 101 patient Bactec 12B cultures. Positive results by Gen-Probe tests were correlated with the growth index (GI) reading on the day of processing as well as the accumulated GI readings. For those 51 with high (greater than or equal to 999) final GIs, 40/40 (100%) M. tuberculosis complex isolates and 9/11 M. avium complex isolates were positive by Gen-Probe, and six other mycobacteria were negative. Of the 25 with moderate final readings (400 less than or equal to GI less than 999), 12/17 M. tuberculosis complex isolates and 1/1 M. avium complex isolates were correctly identified by Gen-Probe; seven other mycobacteria were negative. Of 25 with low readings (GI less than 400), 8/24 M. tuberculosis isolates were correctly identified by Gen-Probe, and no falsely positive test results were obtained with the other probes. All true negative tests on seven other mycobacteria (not M. tuberculosis complex or M. avium complex) had less than 2% hybridization. Of the 24 falsely negative tests on M. tuberculosis complex isolates or M. avium complex isolates, 22 had greater than 2% hybridization with their respective probes. Thus, percent hybridization greater than 2% may be a useful indicator of the need for retesting.

Algorithms↗
PubMed1990

Modified method for testing the quality of albumin-containing enrichments used in growth media for mycobacteria.

Many commercially available media for cultivation of mycobacteria have failed to support the growth of these organisms. This is especially true of media prepared with albumin-containing enrichments. Earlier, we developed a method for rapid identification of good albumin enrichments for agar-based media used to test the susceptibility of tubercle bacilli to pyrazinamide. The method was modified to make testing of the acceptability of albumin enrichments for primary isolation media for mycobacteria possible. We describe here a simple turbidimetric test using a specific Bacillus subtilis strain to assay quickly (24 h) different lots of albumin-containing enrichments that may be used in the preparation of growth media for mycobacteria.

Albumins↗
PubMed1988

Subcutaneous phaeohyphomycosis caused by Xylohypha emmonsii.

The first human phaeohyphomycotic infection caused by Xylohypha emmonsii is described. The patient, an 83-year-old woman, developed a purpuric lesion on her left arm. The pale brown fungal elements observed in biopsy tissue consisted of thin- to thick-walled, oval to spherical, yeastlike cells with single and, occasionally, multiple buds; chains of budding cells; cells with internal septations in one and, rarely, two planes; and septate hyphae. In culture, X. emmonsii grew moderately fast at 25 degrees C, showed minimal growth at 37 degrees C, and failed to grow at 40 degrees C. It produced acropetal chains of one-celled (rarely two-celled) conidia laterally and terminally directly from vegetative hyphal cells.

Aged↗
PubMed1988

Mycobacterium avium complex pseudobacteriuria from a hospital water supply.

From July 1983 through November 1985, organisms belonging to Mycobacterium avium complex were isolated from the urine of 29 patients. Strains recovered from the urine of nine patients from July 1983 through August 1984 were serotyped. Eight of the nine samples belonged to serovar 4. M. avium complex was isolated from the urine of 21 patients during the period from November 1984 through November 1985. While the possibility of a point source contamination was investigated, M. avium complex was recovered from the phenol red solution used for processing urine specimens in the mycobacteriology laboratory and the deionized tap water of that laboratory that is used to make the reagent. M. avium complex serovar 4 was subsequently recovered from the tap water of the laboratory and four hospital wards. During the year following the installation of a microbiological filter for the mycobacteriology laboratory deionized tap water, 2 urine isolates were recovered, compared to 26 the previous year. This study demonstrates the importance of filtration devices at tap water sites that are used to make laboratory reagents and the value of serotyping as a marker for the detection of a specific source of M. avium complex contamination.

Bacteriuria↗
PubMed1984

Pulmonary disease due to Mycobacterium malmoense.

A case of pulmonary disease due to Mycobacterium malmoense was recently diagnosed in a 43-year-old man from Virginia. This organism was isolated from sputum and bronchial washings. This is the first case of documented human infection due to this organism in the United States

Adult↗
PubMed1983

An improved reagent for mycobacterial nitrate reductase tests.

A new crystalline reagent for nitrate reductase tests was compared with standard liquid reagents on 437 strains of mycobacteria. The results for isolates of Mycobacterium avium complex, Mycobacterium kansasii, Mycobacterium gordonae, Mycobacterium scrofulaceum, Mycobacterium fortuitum, and Mycobacterium chelonei agreed 100% with the expected results. Of the 177 Mycobacterium tuberculosis isolates, 4 were negative by the conventional method. Two of these four isolates were positive with the new reagent. Of the positive nitrate tests carried out with liquid reagents, 42% flashed instantly or faded in color; none of the tests carried out with the new crystalline reagent flashed or faded. A stronger color reaction was seen for 28% of the positive tests with the new reagent.

Indicators and Reagents↗
PubMedDate not supplied

Chronic tenosynovitis of the hand due to Mycobacterium nonchromogenicum: use of high-performance liquid chromatography for identification of isolates.

Six cases of chronic tenosynovitis of the hand due to the Mycobacterium terrae complex were identified. All isolates from the six cases were identified as Mycobacterium nonchromogenicum by high-performance liquid chromatography and by testing for susceptibility to ofloxacin and to 5% NaCl. Ethambutol, sulfonamides (or trimethoprim-sulfamethoxazole), erythromycin, and streptomycin are the drugs most active against isolates of the M. terrae complex, and therapy with some combination of these agents plus surgical debridement offers the best current treatment of this disease. This study supports the contention arising from previous case reports of pulmonary disease that M. nonchromogenicum is the pathogenic member of the M. terrae complex.

Adult↗