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S A Larsen

Publications and source records attributed to S A Larsen.

At least 73 records · Page 4Linked to original sources
PubMed1978

Tests for treponemal antibody in CSF.

We studied the potential usefulness of CSF treponemal tests in the diagnosis of neurosyphillis. The CSF was tested with the microhemagglutination test for Treponema pallidum (CSF-MHA-TP test) and with the CSF-FTA test by using undiluted CSF and CSF diluted in saline and in sorbent. In a prospective evaluation, of 177 nonsyphilitics, none had reactive CSF-MHA-TP tests and only one had a reactive CSF-FTA test. However, five of 15 syphilitics with no other evidence of neurosyphilis had reactive CSF-FTA tests. The CSF-FTA test reactivity appeared most likely when the titer of the serum FTA test was high. In a retrospective evaluation of syphilitics with reactive CSF-FTA tests, similar patterns of reactivity occurred in patients with and without other evidence of neurosyphilis. Without other supporting clinical or laboratory data, the diagnostic value of a reactive CSF-FTA test is unknown.

Adult↗
PubMed1977

The FTA-ABS test: a diagnostic help or hindrance?

The fluorescent treponemal antibody absorption (FTA-ABS) test, an excellent confirmatory treponemal test, has been used increasingly for syphilis screening and case detection. To evaluate its performance as an initial test, we did Venereal Disease Research Laboratory (VDRL) slide and FTA-ABS tests on 1,043 patients suspected of having syphilis. When retested in both a local and a reference laboratory, sera from 226 patients with borderline or reactive results demonstrated interlaboratory consistency for the VDRL but not the FTA-ABS. Borderline FTA-ABS results correlated poorly with the diagnosis of syphilis in both laboratories; a reactive FTA-ABS test correlated well only in the reference laboratory. Performance of the test appeared to be diminished by its use in a low-prevalence population and by seemingly minor alterations in the test procedure at the local laboratory.

Absorption↗
PubMed1977

Use of stable, sensitized cells in an indirect microhemagglutination test for melioidosis.

Two evaluations were carried out in this study. The first was a comparison of the standard tube test with the automated microtitration test for the detection of antibodies to Pseudomonas pseudomallei by the indirect hemagglutination method. Data from this comparison indicated that the tests were equivalent. The second evaluation consisted of reproducibility studies on two lots of pyruvic aldehyde-stabilized sensitized erythrocytes in comparison with freshly prepared sensitized erythrocytes in the automated microtitration test. The influence of different types of the microtitration plates used was also examined. Results indicated that the use of stabilized antigens is feasible, and these antigens offer the advantage of being ready for immediate use.

Animals↗
PubMed1976

Immunoglobulin specificity for the fluorescent treponemal antibody-absorption test conjugate.

Quantitative indirect immunofluorescence tests have demonstrated the predominance of immunoglobulin G antibody in most stages of syphilis. A class-specific anti-human immunoglobulin G conjugate is recommended to replace the present fluorescent treponemal antibody-absorption test conjugate. This would allow further definition and standardization of the fluorescent treponemal antibody-absorption test.

Antibody Specificity↗
PubMed1974

Immune response to Listeria monocytogenes in rabbits and humans.

Rabbits were immunized with listeria antigens, staphylococcus antigen, or with both, and the course of their immune response was monitored. Antibodies to Listeria and Staphylococcus were produced in both immunoglobulin M (IgM) and immunoglobulin G (IgG) classes in response to inoculation with the specific antigen. Cross-responses occurred in rabbits injected only with Listeria or only with Staphylococcus, as well as in rabbits injected with both antigens. L. monocytogenes serotype 4d appeared to be immunologically distinct from L. monocytogenes serotype 2 and its cross-reaction with S. aureus. Human sera from bacteriologically confirmed cases of listeriosis were examined to determine the nature of the immunological response of man to Listeria. In the sera studied, IgM was the predominant antibody produced to Listeria, whereas cross-reactions with Staphylococcus were observed in both the IgM and the IgG antibody classes.

Agglutination Tests↗
PubMed1972

Evaluation and standardization of an agglutination test for human listeriosis.

Human sera from patients with culturally confirmed listeriosis were tested for immunoglobulin M (IgM) and immunoglobulin G (IgG) agglutinating antibodies with trypsinized antigens of Listeria monocytogenes, Streptococcus faecalis, and Staphylococcus aureus. The response of humans to listeria infections is mainly IgM rather than IgG as found in animals. The antigens prepared from L. monocytogenes serotypes 1a, 1b, 2, 4b, and 4d were evaluated for specificity with normal sera, sera from patients with various other diseases, and sera from patients with listeriosis. The trypsinized antigens appeared to be specific for listeria antibodies with a cross-reaction rate of from 5.4 to 6%. Cross-reaction with S. aureus can be eliminated by absorption of the serum with S. aureus. This agglutination technique appears to be applicable for diagnostic testing, but, as with all serological procedures, both acute and convalescent sera should be tested.

Absorption↗
PubMed1971

Antibiotic susceptibility patterns of recent isolates of Corynebacterium diphtheriae.

A variety of factors which might affect zone sizes were studied with strains of Corynebacterium diphtheriae; a standard disc method for antimicrobial sensitivity testing was used. Moderate variations in inoculum size, inoculum preparation, and pH of Mueller Hinton agar (MHA) did not appreciably affect zone sizes. The addition of blood to MHA was necessary to insure the growth of all C. diphtheriae strains on all lots of MHA. Zone diameters on MHA with blood were consistently 4 to 9 mm smaller than on plain MHA; however, zone diameters were within the sensitive range for seven antibiotic discs used on both media. Minimal inhibitory concentration (MIC) values for penicillin, erythromycin, and rifampin were determined by a plate dilution method. The geographical source, toxigenicity, and type of the strains showed no significant correlation with MIC values or zone diameters for eight antibiotic discs. When MIC values were compared to obtainable blood levels, all of the strains appeared to be sensitive with MIC values of </= 0.5 mug/ml for penicillin and </= 0.01 mug/ml for erythromycin and rifampin. Strains from persons who failed to have C. diphtheriae eliminated by one course of treatment with penicillin or erythromycin were examined. The susceptibility of these strains did not vary significantly from that of the other strains studied.

Animals↗
PubMed1971

Polyacrylamide gel electrophoresis of Corynebacterium diphtheriae: a possible epidemiological aid.

In this preliminary study, the use of polyacrylamide gel electrophoresis as an aid in the characterization of Corynebacterium diphtheriae was evaluated and a standardized method was developed. The electrophoretic patterns of 17 gravis, 14 mitis, and 2 intermedius types of C. diphtheriae were compared with the electrophoretic patterns of 5 Robinson and Peeney stock gravis serotype strains. Each of the 5 stock serotype strains had different electrophoretic patterns, although some common bands were present. The 17 gravis strains isolated in the United States showed patterns identical to those of the stock gravis serotype II strain. The 14 mitis strains examined produced 6 different electrophoretic patterns, irrespective of geographical location. One mitis pattern corresponded with the pattern of gravis serological type II. The two intermedius strains examined had identical electrophoretic patterns that resembled the pattern of gravis serotype IV. Polyacrylamide gel electrophoresis of C. diphtheriae strains may prove to be a useful epidemiologic tool in establishing the distribution and occurrence of various C. diphtheriae types.

Bacteriological Techniques↗
PubMed1970

Antigenic variation in group A streptococci: types 11 and 9.

A strain of group A Streptococcus which was virulent but M-nontypable was isolated from patients in a hospital nursery during an epidemic. This strain, Boston 11, reacted in T-agglutination tests with antisera for types 9 and 11, an unusual combination. A comparison of this strain with Lancefield's M-11 strain (NCDC SS-721) and Alabama 11 (Provisional 61) revealed three serologically related but distinct strains. Antiserum produced with the Boston 11 strain exhibited similar reactivity with all three "11" strains as well as with M-9 (SS-501) as demonstrated in precipitin tests. Immunodiffusion studies indicated that the Boston 11 antigen was partially identical with the M-11 and M-9 strains and shared at least one antigen with the Alabama 11 strain. The Boston 11 antiserum could be made specific for precipitin tests, but bactericidal activity for the Alabama 11, M-11, and Boston 11 strains was essentially negative.

Agglutination Tests↗
PubMed1969

Acrylamide gel electrophoresis of group A streptococcal cell walls.

Patterns obtained by acrylamide gel electrophoresis of group A streptococcal cell walls were characteristic for M types 1, 2, 3, 4, and 5, respectively. Best results were obtained with cell walls which had been solubilized with a phenol-acetic acid-water mixture. The method will make it possible to compare group A streptococci of epidemiological and clinical significance and to separate components for more critical analysis.

Bacterial Proteins↗
PubMed1966

Growth of lactic acid bacteria in waste waters of vegetable-processing plants.

Waters used in washing, blanching, cooling, and conveying vegetables during processing for freezing were filtered, sterilized, and inoculated with Streptococcus faecalis, S. lactis, or Lactobacillus plantarum. The contents of total nitrogen and total solids were determined, and ninhydrin tests and Benedict's tests for reducing sugars were performed. Substances positive to the ninyhydrin tests and also capable of supporting the growth of the bacteria to high levels of population were found in waters used to blanch cut green beans, but not in the cooling or conveying waters. They were found only in waters following slicing of blanched whole beans. They were also present in waters used in processing purple hull peas at all stages, but only in the waters used to blanch and cool lima beans. The substances were present in waters used to wash and blanch squash, but only in the waters used to blanch greens; they were not found in the cooling waters during the handling of either vegetable. No waters used in the processing of okra yielded a positive ninhydrin test, nor did they support the growth of the lactic acid bacteria.

Enterococcus faecalis↗
PubMedDate not supplied

New technologies for use in the surveillance and control of yaws.

In the Republic of Ghana, treponemal antigen tests performed on finger-prick blood from patients with yaws proved to be as sensitive as those tests performed on whole sera, and this mode of collection was more economical and acceptable than venipuncture. Under field conditions, dark-field microscopic examination of suspect yaws lesions was difficult as compared with collection of serous exudate in heparinized capillary tubes examined later in a reference laboratory. Direct staining of lesion exudate fixed on microscope slides with fluorescein-conjugated human or mouse monoclonal antibody against Treponema pallidum was more sensitive than dark-field examination. However, these techniques could not distinguish between the early lesions of venereal syphilis and those of yaws. An equally sensitive technique used a cloned segment of the T. pallidum (Nichols strain) genome to detect homologous DNA in lesion exudate fixed on nitrocellulose filter paper. The fixation of lesion exudates on microscope slides or nitrocellulose papers may prove to be the easiest method of collecting and transporting such materials to reference laboratories.

Adolescent↗
PubMedDate not supplied

Failure of the Treponema pallidum immobilization test to provide additional diagnostic information about contemporary problem sera.

Two hundred forty-five sera submitted to the Center for Disease Control, Atlanta, Ga., (CDC) were analyzed serologically in an attempt to demonstrate the diagnostic value of the Treponema pallidum immobilization (TPI) test when performed in addition to the fluorescent treponemal antibody-absorption (FTA-Abs) test. Diagnoses for the patients whose sera were tested were based on information supplied by the referring physicians. Fifty-four per cent of the diagnostic problems were resolved merely by the finding of a negative result with the FTA-Abs test. There was agreement between the serologic results of the referring laboratory and those of the CDC for 76% of sera tested by the Venereal Disease Research Laboratory test and for 71% of sera tested by the FTA-Abs test. For patients with treponemal disease, the sensitivity of the TPI test was 56% and that of the FTA-Abs test was 78%. When the FTA-Abs test was reactive, a negative TPI test was not significantly associated with systemic lupus erythematosus (P > 0.6) or other collagen vascular disease (P > 0.6), nor was a positive TPI test associated with treponemal disease (P > 0.09). It is concluded that once the result of the FTA-Abs test is known, the TPI test does not provide additional diagnostic information.

Fluorescent Antibody Technique↗
PubMedDate not supplied

Staining intensities in the fluorescent treponemal antibody-absorption (FTA-Abs) test: association with the diagnosis of syphilis.

In 1984 the reporting system for the fluorescent treponemal antibody-absorption (FTA-Abs) test was changed by the Centers for Disease Control (CDC; Atlanta, GA) to eliminate the borderline report. Factors influencing the reliability of the FTA-Abs test results, i.e., sensitivity, specificity, prevalence of syphilis, prescreening of sera with nontreponemal tests, and reproducibility, were considered before the change in the reporting system was recommended and are reported here. The borderline report, when associated with syphilis, was most frequently also associated with the diagnosis of early primary, dark-field-positive, nontreponemal test-nonreactive syphilis. Whereas elimination of the borderline report decreased the sensitivity of the FTA-Abs test as a confirmatory test from 100% to 99.5%, the specificity increased from 82.5% to 88.7%. The 1+ staining intensity had an association of approximately 5% with the diagnosis of syphilis. The changes in the reporting system were designed to assist the clinician in interpreting the results of the FTA-Abs test in those cases that present diagnostic dilemmas.

Fluorescent Antibody Technique↗
PubMedDate not supplied

Four serologic tests for syphilis: results with comparison of selected groups of sera.

The specificity of the fluorescent treponemal antibody-absorbed (FTA-Abs) test was assessed for 17 sera from syphilitic patients that were nonreactive in the Treponema pallidum immobilization (TPI) test but reactive in the FTA-Abs test. Thirty-three other sera from syphilitic patients and 19 sera from nonsyphilitic individuals were also examined by fluorescent treponemal and microhemagglutination Treponema pallidum (MHA-TP) tests and by the enzyme-linked immunosorbent assay (ELISA). Specific absorptions of sera with calf thymus DNA or Treponema pallidum biotype Reiter (Reiter treponemes) were performed. In quantitative immunofluorescence assays (IFA) with antihuman IgG and IgM conjugates, results were similar to those for reactive sera from a control group. Results of both the MHA-TP and ELISA tests supported the specificity of the FTA-Abs test; reactivity in the latter was not removed by specific absorption either with calf thymus DNA or with Reiter treponemes. This evaluation suggests a format for serodiagnosis in cases in which test results are discrepant.

Enzyme-Linked Immunosorbent Assay↗
PubMedDate not supplied

Evaluation of sera from patients with Lyme disease in the fluorescent treponemal antibody-absorption test for syphilis.

To determine whether the cross-reactivity between Treponema pallidum and Borrelia burgdorferi affects the specificity of the fluorescent treponemal antibody-absorption (FTA-Abs) test for syphilis, sera from patients with Lyme disease or syphilis were examined in a quantitative FTA-Abs test. Sera were diluted serially in phosphate-buffered saline, then in sorbent, and were tested with T. pallidum and B. burgdorferi antigens. Nine of 40 sera from patients with known Lyme disease were reactive at the 1:5 dilution with antigen from T. pallidum; only one serum was reactive at the 1:10 dilution. When both antigens were tested, the titer against B. burgdorferi was always higher than that against T. pallidum. Similarly, sera from patients with syphilis showed cross-reactivity with B. burgdorferi. Although reactivity could be absorbed with Treponemal phagedenis (Reiter strain), simultaneous titration with both antigens was easily performed and designated the etiologic agent.

Antigens, Bacterial↗
PubMedDate not supplied

Tissue fluid penetration and anti-treponemal activity of trospectomycin (a new spectinomycin analog) in the rabbit syphilis model.

The antitreponemal activity of trospectomycin (a novel 6'-propyl analog of spectinomycin) was correlated with concentrations in serum and tissue chamber fluid in a cutaneously-infected rabbit model of syphilis. After single-dose intramuscular (im) injections of trospectomycin, spectinomycin hydrochloride, and aqueous procaine penicillin G(APPG), concentrations of the drugs in paired specimens of serum and tissue fluid were determined and correlated with response of Treponema pallidum-infected lesions. Lesions responded most rapidly in APPG-treated animals. Rapid response correlated with more prolonged levels of APPG in both serum and tissue fluid. Trospectomycin, when given in single doses exceeding 40 mg/kg, surpassed penicillin in peak serum levels (greater than 60 micrograms/ml at 1 hr) but not in duration of activity. Higher and prolonged concentrations of trospectomycin in tissue fluid correlated with more effective clearance of treponemes from cutaneous lesions. Animals treated with less than 40 mg of trospectomycin/kg or with 20-80 mg/kg of the parent compound (spectinomycin hydrochloride) had cutaneous lesions that were persistently darkfield-positive, as confirmed by three or more consecutive smears.

Animals↗