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Biomedical subjects

M A Noble

Publications and source records attributed to M A Noble.

At least 55 records · Page 3Linked to original sources
PubMed1991

Hepatitis B and HIV infections in dental professionals: effectiveness of infection control procedures.

In a survey carried out in 1987 and 1988 in Vancouver British Columbia, 704 dental professionals filled out an anonymous questionnaire and submitted a blood sample. Of those not immunized, 11% had infection with Hepatitis B, with dentists having a rate of 18%, significantly higher than other dental workers. Two carriers of HBsAg were detected and no individuals showed evidence of HIV infection. There were no differences in infection rates by the specific infection control practices. Oriental dental-care workers had a significantly higher rate of infection than other races surveyed. In a multivariate model, race and the number of years in practice were the only significant factors in predicting infection. The use of gloves did not show a protective effect, although a threefold protection rate for gloves is the smallest difference that could be reliably detected. The immunization rate with Hepatitis B vaccine averaged 46%, with fewer dentists being immunized than hygienists. Seroconversion rates were lower in older individuals. Dental professionals had a high risk of Hepatitis B and had not been adequately immunized. Reliance on gloves for operator protection appears to be inadequate.

Adult↗
PubMed1990

Characterization of a neutrophil-inhibitory factor from clinically significant Staphylococcus epidermidis.

Sixteen isolates of Staphylococcus epidermidis recovered from blood cultures of patients were examined for ability to adhere to plastic tubes, for agglutinability with concanavalin A, and for the ability to inhibit the bactericidal activity of neutrophils collected from healthy human volunteers. Neutrophil inhibition was induced by six of nine isolates associated with clinically significant infections but by only one of seven clinically defined as blood contaminants (P = .05). Six of the eight significant bacteremic episodes were associated with neutrophil-inhibitory isolates (P = .03). Neutrophil inhibition was independent of either adherence or ConA agglutination. Neutrophil inhibition may represent an independent virulence factor associated with Staphylococcus epidermidis.

Agglutination Tests↗
PubMed1988

Laboratory diagnosis of Chlamydia trachomatis using two immunodiagnostic methods.

Seven hundred seventy-seven endocervical specimens collected from symptomatic and asymptomatic women in a low-prevalence population were examined for the presence of Chlamydia trachomatis by both enzyme immunoassay (EIA) and by direct immunofluorescence assay (DFA). Overall, 49 (6.2%) of specimens had positive results, however, only 26 had positive results by both assays. Concordant positivity was significantly higher in specimens from symptomatic women not taking antibiotics as compared with all other groups. Test discordance was not influenced by order of specimen collection, number of days of delay before the specimen was processed by EIA, cervical cytologic results, amount of mucopurulence, or presence of a particular bacterial species in simultaneously collected cervical swabs. The EIA optical density (OD) reading appeared to discriminate between the different test result groups more reliably than the number of elementary bodies seen on the DFA slide. Specimens with an OD reading greater than 0.300 and less than 0.060 can be interpreted with assurance as positive and negative, respectively. Caution may be necessary with specimens with intermediate values.

Adult↗
PubMed1988

Human coproantibody secretory immunoglobulin A response to Yersinia species.

A semiquantitative indirect immunofluorescence assay to detect coproantibody secretory IgA (SIgA) was established to investigate the human intestinal immune response to Yersinia species. This assay was based on microagglutination of SIgA in fecal specimens with the patient's homologous organism. Two populations of patients were defined, those who produced an agglutinating (2+) SIgA response and those who did not. A comparison between SIgA production and standard in vitro virulence-related characteristics of infecting organisms, including autoagglutination, calcium dependence, plasmid carriage, and absorption of Congo red, mouse virulence, and clinical presentation, was performed. A positive (2+) SIgA result was associated with acute enteric illness (positive predictive value, 78.6%) and mouse virulence (positive predictive value, 85.7%). When patients with active inflammatory bowel disease were excluded, the positive predictive value of SIgA for mouse virulence and acute enteric disease became 100%. In addition to strains of Yersinia enterocolitica 4,O:3, strains generally characterized as nonpathogenic, including Yersinia frederiksenii, were found to be associated with acute disease, mouse virulence, and stimulation of SIgA. The indirect immunofluorescence assay for detection of SIgA response appears to be a useful indicator of pathogenic strains of yersiniae recovered from enteric specimens.

Acute Disease↗
PubMed1987

Gastrointestinal features of culture-positive Yersinia enterocolitica infection.

Yersinia enterocolitica was cultured from feces of 122 symptomatic adults in a single facility using selective culture media; all isolates were confirmed in an independent reference laboratory. Of 128 isolates, multiple serotypes were defined and all were biochemically typical for Yersinia enterocolitica. Other agents were seen in 20 patients; of these, seven were Yersinia fredriksenii and six were Clostridium difficile. Diarrhea (80%) and abdominal pain (64%) were common, whereas other features such as fever (9%) and bloody stools (8%) were unusual. Use of antibiotics (24%) or opiates (28%) in the month before culture was common. The terminal ileum was seen radiographically in 20 patients, but only two barium studies showed abnormalities. Fiberoptic endoscopy and biopsy studies, done in greater than 50% of the cases, showed minimal or no changes in most patients. However, 3 patients had pseudomembranous colitis with concomitant Clostridium difficile cytotoxin and 7 had diffuse severe colitis. New culture techniques, and possibly geographic differences, have contributed to the high isolation rates of this organism. Yersinia enterocolitica occurs sporadically, involves a variety of serotypes, and is associated with a broader clinical spectrum than was formerly appreciated.

Adolescent↗
PubMed1987

Epidemiology and clinical features associated with Blastocystis hominis infection.

A retrospective chart review was performed on 100 patients infected with Blastocystis hominis (Bh) and 50 randomly selected age and sex matched controls to examine the clinical and epidemiologic features associated with this organism. The finding of greater than 5 Bh per oil immersion field (1,000 X) was significantly associated with acute presentation of symptoms but was not predictive of the presence of gastrointestinal symptoms. Of patients infected with Bh, 57.5% had recently travelled to the tropics or had consumed untreated water as compared to 12.2% of controls (p less than 0.001). Forty Bh-positive patients were assessed on more than one occasion. No significant differences appeared to exist in the clinical responses of those treated with Metronidazole (14/18; 77.8%) or with dietary management (6/6; 100%) as compared with those not receiving treatment (13/16:81.2%). Patients tended to become less symptomatic with time and in the absence of specific treatment, and therefore treatment with Metronidazole may not be warranted in light of the natural history of Bh infection.

British Columbia↗
PubMed1987

Clinical significance of virulence-related assay of Yersinia species.

During the 42-month period from June 1982 through December 1985, 215 fecal specimens from 171 patients were found to be positive for yersiniae by using a combination of CIN agar and cold enrichment. Isolates were tested for markers of virulence including carriage of a plasmid 42 megadaltons in size, calcium dependence, autoagglutination, Congo red uptake, pyrazinamidase activity, fermentation of salicin, and hydrolysis of esculin. The results were correlated to symptoms in patients. A total of 80 Yersinia enterocolitica and 52 Y. enterocolitica-like strains (42 Y. frederiksenii, 8 Y. intermedia, and 2 Y. kristensenii) were examined. Positive virulence-related tests were as follows (for Y. enterocolitica, Y. frederiksenii, Y. intermedia, and Y. kristensenii, respectively): pyrazinamidase negativity, 12.5, 0, 0, and 50%; Congo red positivity, 5, 7.1, 87.5 and 0%; calcium dependence, 3.8, 0, 0, and 0%; autoagglutination positivity, 8.8, 0, 0, and 0%; carriage of the 42-megadalton plasmid, 28.6, 73.2, 5.7, and 0; salicin and esculin negativity, 12.5, 0, 0, and 50%. The isolates recovered from symptomatic patients were characterized in relation to the presenting symptoms. Isolates from 12 of 32 (37.5%) patients with acute-onset diarrhea and 9 of 30 (30.0%) patients with chronic symptoms expressed at least one virulence feature. No individual test or group of tests was consistently associated with onset or either type of symptoms. Routine testing of plasmid carriage, uptake of Congo red, calcium dependence, autoagglutination, and pyrazinamidase activity did not appear to provide information that would link the presence of symptoms with the virulence potential of fecal isolates of yersiniae.

Acute Disease↗
PubMed1987

Commercial latex agglutination test for detection of Clostridium difficile-associated diarrhea.

A commercially available latex agglutination test for Clostridium difficile was compared with a cell culture cytotoxin assay and bacteriological culture for the laboratory diagnosis of C. difficile-associated diarrhea and colitis (CAD). Stool specimens from 626 patients were tested by the three methods, and specimens from 118 patients (19%) were positive by at least one of the methods. The results of the three tests agreed in 88% of the specimens tested, overall, but they agreed in only 34% of the 118 positive specimens. Ninety-three patients were evaluated to assess the significance of positive and negative results for each assay. Of 40 patients found to have CAD, 70% were positive by the cytotoxin assay, 78% were positive by the latex agglutination test, and 90% were culture positive. Of 53 patients who did not have CAD, 2% were positive by the cytotoxin assay, 8% were positive by the latex test, and 4% were culture positive. The detection of CAD was improved by using the tests in combination, and 97% of specimens positive by two or three methods were from patients who had CAD. Testing of multiple specimens from individual patients also increased the sensitivity of detection of CAD. The results suggest that the latex agglutination test may be useful for rapid diagnosis of CAD, especially in laboratories that lack cell culture facilities. However, the accuracy of CAD detection is improved when the latex test is used in combination with culture or the cytotoxin assay.

Adult↗
PubMed1986

Inhibition of human neutrophil bacteriocidal activity by extracellular substance from slime-producing Staphylococcus epidermidis.

The role of slime produced by Staphylococcus epidermidis as a virulence factor has been investigated by preincubating human neutrophils in fractions of extracellular material from cultures of slime-producing and non-slime-producing S. epidermidis. Extracellular product (molecular weight greater than 300,000) from slime-producing S. epidermidis did not affect neutrophil phagocytosis but did produce a generalized loss of bacteriocidal activity which was not found with non-slime-producing S. epidermidis, or broth.

Biological Products↗
PubMed1986

Aminoglycoside usage in a university teaching hospital.

A retrospective chart review examined the use of aminoglycosides in a university teaching hospital over a six month period. The study found 273 patients received 323 courses of aminoglycoside therapy. Significant issues addressed include the frequent use of aminoglycosides as surgical prophylactic agents, the prescribing of drugs to patients at increased risk of toxicity and the infrequency of appropriate monitoring. Nephrotoxicity was noted in 7% of patients.

Aminoglycosides↗
PubMed1984

Evaluation of a rapid method for the detection of vaginal group B streptococci in women in labor.

Group B streptococci infection is an important cause of neonatal morbidity and mortality. Effective therapeutic intervention has been prevented to date by our inability to rapidly detect vaginal colonization. Material obtained from the lower vagina of 414 women in labor was cultured, incubated in modified Islam serum starch broth and observed on the ward for the production of orange carotenoid pigment specific for group B streptococci. Subcultures yielded 48 true group B streptococci-positive results. For the Islam broth, the pigment appeared in 2 to 22.5 hours (median, 12.5 hours). The test was shown to have a sensitivity of 96% and a specificity of 100% for group B streptococci. This study demonstrated a simple inexpensive method of detecting vaginal group B streptococci colonization which does not require sophisticated 24-hour laboratory facilities. The method holds promise as a screening test for future intervention studies.

Bacteriological Techniques↗