Biomedical subjects

C A Gaydos

Publications and source records attributed to C A Gaydos.

77 records · Page 5Linked to original sources

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↗

PubMedDate not supplied

Evaluation of Abbott Testpack Chlamydia for detection of Chlamydia trachomatis in patients attending sexually transmitted diseases clinics.

This work compares a rapid solid-phase EIA (Abbott TestPack Chlamydia) to tissue culture and a direct fluorescent antibody test (Syva Microtrak) for detection of C. trachomatis in 436 patients attending two inner-city sexually transmitted diseases (STD) clinics. The prevalence of C. trachomatis by culture was 12% (5% in men, 15% in women). Overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TestPack compared to culture were 70%, 98%, 80%, and 96% respectively. In men, 12 specimens were positive by TestPack, while only eight specimens were positive by culture. Six TestPack-positive, culture-negative specimens were further evaluated by centrifugation of culture transport media and examination of the sediment for chlamydia elementary bodies (EBs) using fluorescent monoclonal antibodies to C. trachomatis. Using this procedure, five of six culture negative specimens contained EBs (revised sensitivity 85%, specificity 99%, PPV 92%, NPV 99%). In 285 women evaluable in culture and TestPack, 44 (15%) specimens were culture positive; TestPack was positive in 29 (sensitivity 66%) culture positive women. Of 241 culture negative patients, 238 had negative TestPack results (specificity 99%) and no EBs were detected in the culture-negative, TestPack-positive specimens. Twenty-three (8%) Microtrak specimens were unsatisfactory for testing; two of these were culture and TestPack positive. Therefore, of 263 specimens evaluable using Microtrak, 42 (16%) specimens were culture positive; Microtrak was positive in 32 (sensitivity 76%) culture-positive women. Abbott TestPack Chlamydia is a rapid (25 minute), visually read format requiring no specialized equipment for detection of chalmydia infections with a sensitivity comparable to that of Microtrak.

Adult↗

PubMedDate not supplied

Urine as a diagnostic specimen for the detection of Chlamydia trachomatis in Malaysia by ligase chain reaction.

BACKGROUND AND OBJECTIVES: Noninvasive urine screening for Chlamydia trachomatis infections offers a valuable public health tool, which could be of vast importance in chlamydial control programs. The authors evaluated a new DNA amplification method, ligase chain reaction (LCR). GOALS: The goal was to ascertain whether urine testing could be used as screening method to detect C. trachomatis infections in commercial sex workers, patients at sexually transmitted diseases clinic, and asymptomatic patients in Kuala Lumpur, Malaysia. METHODS: First-void urine specimens from 300 men and 300 women were tested by LCR, as well as by a commercially available enzyme immunoassay. The LCR assay amplifies specific sequences within the chlamydial plasmid with ligand-labeled probes, and the resultant amplicons are detected by an automated immunoassay. Specimens with discrepant results were confirmed by another LCR of the specimen that targeted the gene for the major outer membrane protein (OMP1). RESULTS: There were 31 LCR-positive male urine and 37 LCR-positive female urine specimens. The resolved sensitivity and specificity for the LCR of the male urine specimens were 100% and 99.6%, respectively, whereas for female urine specimens, the sensitivity and specificity were 100% and 98.5%, respectively. After resolution of discrepant test results by OMP1 LCR, the prevalence was 10% for men and 11% for women. The urine enzyme immunoassay was not useful in diagnosing C. trachomatis infections in either men or women, as the resolved sensitivities were 10% and 15.2%, respectively. The specificities were 99.6% for men and 98.9% for women. CONCLUSIONS: Testing first-void urine specimens by LCR is a highly sensitive and specific method to diagnose C. trachomatis infections in men and women, providing health care workers and public health officials with a new molecular amplification assay that uses noninvasive urine specimens for population-based screening purposes.

Chlamydia Infections↗

PubMedDate not supplied

Gene typing of Chlamydia trachomatis by polymerase chain reaction and restriction endonuclease digestion.

A portion of the major outer membrane protein (MOMP) gene from 15 Chlamydia trachomatis serovars was amplified by polymerase chain reaction (PCR) and the product was analyzed by restriction fragment length polymorphism (RFLP). A set of primers was used to amplify an 871 base pair gene fragment encompassing the 4 hypervariable regions of MOMP. AluI digestion of the product gave distinctive patterns for the 15 serovars as demonstrated on silver-stained polyacrylamide gels. A triple digest with EcoRI, HinfI, and HpaII allowed improved discrimination between closely related serovars (C, H, I, J, L3). PCR and RFLP were used to type 50 wild-type clinical isolates and results were compared to results of the solid-phase enzyme immunoassay typing method. These isolates represented the most prevalent genital serovars (D, E, F, K, I and J) in the local sexually transmitted diseases clinic population. For specimens containing 1 serovar, the results of the two methods were similar for 42 samples and discordant for 1 sample. In addition, two samples showed evidence of mixed infection with two serovars as identified by both methods. Five additional specimens contained two serovars, as shown by one or both methods. In all five such specimens, the two typing methods agreed on at least one of the two serovars. For both single and multiple serovar specimens, there was concordance between the two typing methods for 16/17 E serovars, 8/9 D serovars, 8/8 F serovars, 7/7 I serovars, 7/7 J serovars, 5/8 K serovars, and 0/2 G serovars.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Outer Membrane Proteins↗