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Biomedical subjects

B A Gunn

Publications and source records attributed to B A Gunn.

13 recordsLinked to original sources
PubMed1994

Reproducibility of three identification systems for biotyping of coagulase-negative staphylococci.

Three commercial identification systems were evaluated as tools for biotyping coagulase-negative staphylococci. Emphasis was placed on the reproducibility of component tests and not on the ability of these kits to identify these bacteria accurately. Forty-seven clinical and reference strains of Staphylococcus were tested in duplicate with each system. The Staph-Ident profile of test results changed for 20 strains on repeat testing, the Staph-Trac profile changed for 10 strains, and the Vitek GPI profile changed for 14 strains. The component tests of each system that were responsible for these profile changes were identified.

Bacterial Typing Techniques↗
PubMed1994

The effects of nonclassic pediatric bacterial pathogens on the usefulness of the Directigen latex agglutination test.

Haemophilus influenzae type b, Escherichia coli, Neisseria meningitis, Streptococcus agalactiae, and Streptococcus pneumoniae are classically the predominant meningeal pathogens of children. The Directigen latex agglutination test identifies these pathogens by detecting specific antigens in cerebrospinal fluid (CSF) and urine. The authors tested 1151 specimens from 791 children with suspected meningeal infections. They found that the sensitivity of the Directigen test for detecting the five classic CSF pathogens of children was 83.3% with CSF and 60% with urine specimens. In detecting all pathogens, however, the sensitivity was only 50% with CSF and 37.5% with urine. Thus, an increased prevalence of nonclassic pathogens in a pediatric population adversely affects the efficacy of the Directigen test for confirming a diagnosis of meningitis and emphasizes the diagnostic importance of the clinical history and other routine CSF tests.

Antigens, Bacterial↗
PubMed1989

Comparative virulence of human isolates of coagulase-negative staphylococci tested in an infant mouse weight retardation model.

Human infections caused by coagulase-negative staphylococci have steadily increased in numbers and severity. Causes may be the use of artificial prostheses, immunocompromising chemotherapy and radiation therapy, and sophisticated surgical techniques, to name a few. Although the infectivity of coagulase-negative staphylococci as a group has been well documented for humans, attempts to study the pathogenesis of infections caused by individual species of coagulase-negative staphylococci have been hampered by the lack of an animal model that is not refractory to infection by these organisms. In the study reported here, a 2-day-old-mouse weight retardation test was used to assay the virulence of 60 clinical and reference strains of coagulase-negative staphylococci. These strains represented eight species of coagulase-negative staphylococci. The most virulent strains were demonstrated to be of the species Staphylococcus haemolyticus, S. saprophyticus, and S. epidermidis. The data further suggest that production of slime is a marker of virulence in S. epidermidis and that intraspecies differences in virulence occur.

Animals↗
PubMed1988

Staphylococcus haemolyticus urinary tract infection in a male patient.

Urinary tract infections caused by staphylococci are usually attributed to Staphylococcus epidermidis or S. saprophyticus. The case study reported here describes a persistent urinary tract infection caused by S. haemolyticus in a 38-year-old male whose infection was ultimately resolved through the use of the antibiotic trimethoprim-sulfamethoxazole.

Adult↗
PubMed1984

Chocolate agar, a differential medium for gram-positive cocci.

Reactions incurred on chocolate agar by gram-positive cocci were correlated with species identity. Darkening and clearing of the medium was usually associated with the species Staphylococcus epidermidis, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus faecalis. Yellowing of chocolate agar was associated with alpha-hemolytic species of Streptococcus. The study demonstrated that reactions occurring on chocolate agar are useful in identifying gram-positive cocci.

Agar↗
PubMed1981

Comparison of methods for identifying Staphylococcus and Micrococcus spp.

Three methods employed to distinguish staphylococci from micrococci were compared, using clinical and environmental strains. When these methods are used, misinterpretation of results, as well as erratic results, may occur, and suggestions for eliminating these problems are provided. The most sensitive test that combines ease of use and speed in obtaining results for distinguishing the two genera is the lysostaphin susceptibility test. Two other tests, facultatively anaerobic growth in semisolid thioglycolate agar and fermentation of dextrose, may also be used to distinguish these two genera, but results are often slow in developing, are subject to technical difficulties, and may lead to incorrect assignment of certain species of staphylococci and micrococci to their proper genera.

Bacteriological Techniques↗
PubMed1980

Serum gentamicin assay by a radiometric procedure.

A new radiometric (BACTEC) microbiologic procedure, using a 14C-urea substrate and a Proteus species culture, was compared with three microbiologic assays and a radioimmunoassay (RIA) method for determination of gentamicin levels in serum. The non-radiometric microbiologic assays did not differ significantly from the RIA assay, but the BACTEC method showed significant differences with specimens containing greater than 4 microgram/ml gentamicin. Overall, the BACTEC assay was found to be simple to run, fast and reproducible. At concentrations of gentamicin less than 4 microgram/ml, it was just as accurate as were the microbiologic assays. However, at concentrations greater than 4 microgram/ml, the BACTEC assay read consistently less than RIA and the other assays. Because of the BACTEC assay's high cost per single test, it cannot approach the utility of the rapid, easy, reliable, and comparatively inexpensive microbiologic assays. The BACTEC assay is, however, a useful alternative to the RIA method in laboratories that already have radiometric equipment and in which batching of serum samples for gentamicin assay is necessary.

Biological Assay↗
PubMed1977

Selective and enhanced recovery of group A and B streptococci from throat cultures with sheep blood agar containing sulfamethoxazole and trimethoprim.

Sheep blood agar containing 23.75 microgram of sulfamethoxazole and 1.25 microgram of trimethoprim (SXT-BA) per ml was compared with conventional sheep blood agar (SBA) for isolating group A and B streptococci from throat cultures. This selective medium allowed much better recovery of group A and B streptococci and suppressed the growth of the normal flora, including "viridans" streptococci. In an initial study of 700 throat cultures, SXT-BA recovered 42% more group A and 49% more group B streptococci than did SBA. When SXT-BA was introduced into the routine microbiology laboratory and used by a number of medical technologists. SXT-BA recovered 28% more group A and 37% more group B streptococci than did SBA. In addition, the selective medium inhibited 83% of the non-group A and B streptococci that were recovered by SBA.

Agar↗