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Biomedical subjects

G V Doern

Publications and source records attributed to G V Doern.

At least 145 records · Page 8Linked to original sources
PubMed1986

Susceptibility of Haemophilus influenzae to amoxicillin/clavulanic acid, erythromycin, cefaclor, and trimethoprim/sulfamethoxazole.

A total of 126 strains of Haemophilus influenzae were examined for susceptibility to amoxicillin/clavulanic acid, trimethoprim/sulfamethoxazole, cefaclor, and erythromycin by an agar dilution procedure. Fifty strains (eight type B, 42 non-type B), all with ampicillin minimal inhibitory concentrations (MIC) of greater than or equal to 6.2 micrograms/ml, produced beta-lactamase. The remaining 76 strains (18 type B, 59 non-type B) were beta-lactamase-negative. All of these strains had ampicillin MICs of less than or equal to 0.8 micrograms/ml. The combination of amoxicillin and clavulanic acid (2:1) was highly active against all strains tested. With the exception of two strains with amoxicillin/clavulanic acid MICs of 1.6/0.8 ug/ml, all strains were inhibited by concentrations of less than or equal to 0.8/0.4 ug/ml. Trimethoprim/sulfamethoxazole was also found to be highly active (MICs uniformly less than or equal to 0.1/1.9 ug/ml). Cefaclor and erythromycin were the least active of the agents tested. Fourteen strains (10.6%) had cefaclor MICs of greater than 32 ug/ml. Forty-seven strains (35.6%) had erythromycin MICs of greater than 8 micrograms/ml. With the exception of amoxicillin/clavulanic acid beta-lactamase production did not seem to influence the activity of any of the antimicrobials tested. Minimum inhibitory concentrations of amoxicillin/clavulanic acid, although still well within achievable serum levels, were approximately one twofold dilution higher with beta-lactamase-producing H. influenzae type B strains than with beta-lactamase-negative strains.

Amoxicillin↗
PubMed1986

Screening for bacteriuria with the LN strip test.

Recently, the LN strip test was introduced for purposes of rapid screening of urine specimens for bacteriuria. The LN strip test permits detection of urinary leukocyte esterase and nitrite. A total of 2,481 unselected urine specimens from three tertiary care hospitals were examined using the LN strip test and the results were compared with those obtained with a conventional quantitative culture technique. When the results of the leukocyte esterase and nitrite tests were combined, the sensitivity and specificity of the LN strip test were 88.8% and 71.3%, respectively, based on culture results of greater than or equal to 10(5) CFU/ml. Test sensitivity decreased at greater than or equal to 10(4) CFU/ml, whereas test specificity increased.

Bacteriuria↗
PubMed1986

Prevalence of antimicrobial resistance among clinical isolates of Haemophilus influenzae: a collaborative study.

The prevalence of antimicrobial resistance was assessed among a total of 3,356 clinical isolates of Haemophilus influenzae obtained from 22 medical centers distributed throughout the United States during the period July, 1983 through June, 1984. All strains were examined for beta-lactamase production with a rapid acidometric assay and for resistance to ampicillin, chloramphenicol, cephalothin, cefamandole, cefaclor, tetracycline, and erythromycin with a standardized disk diffusion procedure. The overall rate of beta-lactamase production was 15.2%, although results of disk diffusion tests suggested that the overall rate of ampicillin resistance was 19.5%. Twenty-one percent of encapsulated type b strains produced beta-lactamase; 12.1% of non-type b strains were beta-lactamase positive. Specific rates of beta-lactamase production obtained at individual study centers varied widely with no evidence of geographic clustering. The highest rates of beta-lactamase production were observed with isolates of H. influenzae recovered from infants and young children, and from blood and cerebrospinal fluid specimens. The overall rate of chloramphenicol resistance was 0.6%. The prevalence of cephalothin, cefamandole, cefaclor, tetracycline, and erythromycin resistance was 9.9%, 2.4%, 2.8%, 6.4%, and 64.2%, respectively. beta-Lactamase positive isolates of H. influenzae had higher rates of resistance to all of the cephalosporins than did strains that lacked beta-lactamase.

Adolescent↗
PubMed1986

Clinically expedient reporting of rapid diagnostic test information.

With the development of rapid diagnostic tests in the clinical microbiology laboratory has come an awareness of the importance of rapid results reporting. Clearly, the potential clinical impact of rapid diagnostic tests is dependent on expeditious reporting. Traditional manual reporting systems are encumbered by the necessity of transcription of test information onto hard copy reports and then the subsequent distribution of such reports into the hands of the user. Laboratory computers when linked directly to CRTs located in nursing stations, ambulatory clinics, or physician's offices, both inside and outside of the hospital, permit essentially instantaneous transfer of test results from the laboratory to the clinician. Computer-assisted results reporting, while representing a significant advance over manual reporting systems is not, however, without problems. Concerns include validation of test information, authorization of users with access to test information, mechanical integrity, and cost. These issues notwithstanding, computerized results reporting will undoubtedly play a central role in optimizing the clinical impact of rapid diagnostic tests.

Clinical Laboratory Techniques↗
PubMed1986

Detection of rotavirus with a new polyclonal antibody enzyme immunoassay (Rotazyme II) and a commercial latex agglutination test (Rotalex): comparison with a monoclonal antibody enzyme immunoassay.

A total of 176 human fecal specimens were examined for the presence of rotavirus by four different assays: a monoclonal antibody enzyme immunoassay; the original polyclonal antibody enzyme immunoassay marketed by Abbott Laboratories, North Chicago, Ill. (Rotazyme I); a modification of this assay which is now commercially available (Rotazyme II); and a latex agglutination test (Rotalex) recently introduced by Medical Technology Corp., Somerset, N.J. In addition, selected specimens were examined for the presence of rotavirus by electron microscopy, immune electron microscopy, and RNA gel electrophoresis. A total of 40 specimens were positive in the monoclonal antibody enzyme immunoassay, and 136 were negative. Using the results obtained with this procedure as the reference standard, we found the sensitivities of the Rotazyme I, Rotazyme II, and Rotalex tests to be 97.4, 100, and 81.6%, respectively. The specificities of these three procedures were 88.8, 83.9, and 100%, respectively.

Antibodies, Monoclonal↗
PubMed1986

Effect of medium composition on results of macrobroth dilution antifungal susceptibility testing of yeasts.

A total of 62 different clinical yeast isolates were examined for susceptibility to four antifungal agents, amphotericin B, 5-fluorocytosine (5-FC), ketoconazole, and miconazole, using synthetic amino acid medium-fungi (SAAM-F), buffered yeast nitrogen broth (BYNB), Kimmig broth, casein-yeast-glucose broth (CYG), antibiotic medium 3-FDA (ANTI-3), and tryptic soy broth (TSB). A macrobroth dilution format was used with MICs determined after incubation for 24 and 48 h. All analyses were performed in duplicate. In general, MICs were more reproducible after 48 h of incubation. Furthermore, with certain medium-antifungal agent combinations, MICs determined after incubation for 48 h were significantly higher than those determined after 24 h. For instance, with 5-FC irrespective of the medium used, greater than 25% of all 48-h MICs were more than one twofold dilution higher than the corresponding MICs determined after incubation for 24 h. Similar observations were made with amphotericin B when tested with BYNB and CYG and with the imidazoles when tested in all of the media except CYG. The actual MICs obtained with the different antifungal agents were clearly influenced by the test medium used. The rank order of amphotericin B MICs according to test medium was as follows: BYNB greater than SAAM-F = Kimmig = CYG = ANTI-3 = TSB. With 5-FC, the following pattern was observed: Kimmig = ANTI-3 greater than SAAM-F = CYG = TSB greater than BYNB. For both imidazoles, ketoconazole and miconazole, the rank order of MICs according to test medium was BYNB = Kimmig = CYG = ANTI-3 = TSB greater than SAAM-F. The results of this investigation suggested that broth dilution susceptibility testing of yeasts is best performed with an incubation period of 48 h. Furthermore, medium composition can significantly influence the results of such testing.

Amphotericin B↗
PubMed1985

Susceptibility testing with the sensititer breakpoint broth microdilution system.

The antimicrobial susceptibility profiles of a total of 318 aerobic and facultatively anaerobic bacteria (255 gram-negative bacilli and 63 gram-positive cocci) were determined, using a new commercially available breakpoint broth microdilution procedure (Sensititer Breakpoint System (SBS), Gibco Diagnostics, Inc., Madison, WI) that categorizes test results in the form of susceptibility categories: susceptible, intermediate, and resistant. Results obtained with the SBS were compared with those achieved with a standardized disk diffusion procedure. Among a total of 4,414 organism-antimicrobic comparisons, concordance between the results of the SBS and the disk diffusion procedure was observed in 3,888 cases (88.1%). Four hundred twenty-three (9.6%) minor discrepancies, 45 (1.0%) major discrepancies, and 58 (1.3%) very major discrepancies were noted. Arbitration of major and very major discrepancies with a full-range minimum inhibitory concentration (MIC) procedure confirmed the results of the SBS in 53.4% of cases. A single organism-antimicrobial combination, the nonenterococcal streptococci tested against the aminoglycosides, yielded a significant number of very major errors which were arbitrated in favor of the disk diffusion result. These errors were probably due to poor growth of the test organism in the broth medium used for performing the SBS test (i.e., cation-supplemented Mueller-Hinton broth). With this exception, the SBS was found to be at least as accurate as the standardized disk diffusion procedure.

Anti-Bacterial Agents↗
PubMed1985

Clinical impact of rapid susceptibility testing.

The clinical impact of susceptibility testing in general, and rapid same-day susceptibility tests in particular, was assessed from two perspectives: does the performance of susceptibility testing in the laboratory influence the clinical use of antibiotics? Does laboratory susceptibility testing affect the outcome of patients with infectious diseases? The following conclusions were derived from this investigation. In vitro susceptibility testing does significantly influence antibiotic usage, but it is difficult to demonstrate a direct relationship between the results of the susceptibility tests and disease outcome. There is little objective evidence to support the contention that rapid susceptibility tests have a greater clinical impact than traditional overnight procedures. Additional studies directed at addressing this issue are clearly necessary, however; in the absence of such studies, routine performance of same-day susceptibility testing should be considered only if the cost of such testing is less than the cost of overnight procedures, or if cost is not a limiting consideration.

Anti-Bacterial Agents↗
PubMed1984

Detection of cytomegalovirus antibody with two commercially available assays, an indirect hemagglutination test and an enzyme immunosorbent assay.

By the use of two reference procedures, an indirect hemagglutination assay and a complement fixation test, the presence or absence of cytomegalovirus (CMV) antibody was determined for 221 human sera. Ninety-nine sera (44.8%) were found to contain CMV antibody. The remaining 122 sera (55.2%) lacked detectable CMV antibody. These same sera were then analyzed by two recently introduced, commercially available CMV antibody assays, an indirect hemagglutination test (IHA-c; Cetus Corp., Emeryville, Calif.) and an enzyme-linked immunosorbent assay (ELISA; M. A. Bioproducts, Walkersville, Md.). With the results of the reference procedures as true evidence of the presence or absence of CMV antibody, the sensitivity of the IHA-c was found to be 100%; the specificity was 98.4%. The sensitivity of the ELISA was also 100%; the specificity was 96.7%. The overall accuracies of these procedures were 99.1 and 98.2%, respectively. Time and motion studies revealed the IHA-c procedure to be faster and technically less demanding than the ELISA procedure.

Antibodies, Viral↗
PubMed1984

Laboratory identification of Haemophilus influenzae: effects of basal media on the results of the satellitism test and evaluation of the RapID NH system.

The effects of four different basal media, tryptic soy agar, brain heart infusion agar, nutrient agar, and Mueller-Hinton agar, were investigated with respect to the identification of Haemophilus influenzae with a satellitism test in which X and V growth factors were supplied by factor-impregnated filter paper strips. A total of 187 recent clinical isolates of H. influenzae were examined. Of these, 179 strains (95.7%) were correctly identified with tryptic soy agar, 173 (92.5%) with brain heart infusion agar, 105 (56.1%) with nutrient agar, and 133 (71.1%) with Mueller-Hinton agar. Failure to obtain a correct identification was usually the result of satelliting growth around V factor-containing strips, possibly due to the presence of trace amounts of hemin in the basal media, or was because of an absence of growth due to nutritional deficiencies in the basal media. All 187 H. influenzae strains were also examined with a new biochemical and chromogenic substrate micromethod, the RapID NH system (Innovative Diagnostics Systems, Inc., Decatur, Ga.). A total of 168 (89.8%) strains were correctly identified with this system.

Culture Media↗
PubMed1984

Evaluation of the DMS Rapid E system for identification of clinical isolates of the family Enterobacteriaceae.

A total of 387 unique clinical isolates of the family Enterobacteriaceae were examined with the new DMS Rapid E gram-negative identification system (DMS Laboratories, Inc., Flemington, N.J.) and the API 20E procedure (Analytab Products, Plainview, N.Y.). Altogether, 376 strains (97.2%) were correctly identified to species level within 4 h with the DMS Rapid E system; 366 strains (94.6%) were correctly identified with the API 20E after overnight incubation.

Bacteriological Techniques↗
PubMed1983

Species identification and biotyping of staphylococci by the API staph-ident system.

The API Staph-Ident system, a commercially available biochemical and chromogenic substrate micromethod, was evaluated as a means for identifying the species and determining the biotypes of human strains of staphylococci routinely encountered in a clinical microbiology laboratory. The species identity of 152 of 188 (80.9%) unique clinical isolates of staphylococci was correctly predicted by this method after 5 h of incubation according to the recommendations of the manufacturer. When results were determined after 24 h of incubation, the overall accuracy of this procedure was 90.4%. The API Staph-Ident system was not an adequate procedure for assessing strain biotypes since the patterns of biochemical reactivity observed with 53 of 54 (98.2%) unique isolates of Staphylococcus aureus were identical. Similarly, 58 of 62 (93.6%) different strains of S. epidermidis yielded the same biochemical profile.

Bacteriological Techniques↗
PubMed1983

Selective media for recovery of Haemophilus influenzae from specimens contaminated with upper respiratory tract microbial flora.

Isolation of Haemophilus influenzae from specimens contaminated with upper respiratory tract microbial flora was attempted with three different media: enriched chocolate agar, chocolate agar plus vancomycin, and chocolate agar plus vancomycin, bacitracin, and clindamycin. Recovery rates of H. influenzae from 852 pediatric pharyngeal swab specimens were 6.0, 28.5, and 59.9%, respectively.

Adolescent↗
PubMed1983

Detection of bacteremia in patients receiving antimicrobial therapy: an evaluation of the antimicrobial removal device and 16B medium.

A total of 1097 blood specimens obtained from patients receiving antibacterial antimicrobial agents were processed by three blood culture systems: standard aerobic and anaerobic radiometric media, resin-containing radiometric medium (16B; Johnston Laboratories, Cockeysville, Md.), and aerobic and anaerobic radiometric media inoculated with blood processed in an Antimicrobial Removal Device (Marion Laboratories, Kansas City, Mo.). A total of 73 cultures, representing 45 unique septic episodes, yielded 81 clinically significant organisms. Forty-six organisms (28 septic episodes) were recovered in standard radiometric medium. 16B medium yielded 63 organisms (37 septic episodes). Sixty-nine organisms (42 septic episodes) were isolated from radiometric blood cultures inoculated with Antimicrobial Removal Device-processed blood. Contamination rates were not significantly different among the three systems. In comparison with standard radiometric blood cultures, the length of time to detection of positive blood cultures was shorter with both 16B medium and with Antimicrobial Removal Device-processed cultures. Comparison of the latter two systems suggested enhanced recovery of clinically significant organisms in radiometric blood cultures inoculated with blood processed in the Antimicrobial Removal Device. There was no difference in the length of time to detection of positive blood cultures.

Anti-Bacterial Agents↗
PubMed1982

Evaluation of a commercial latex agglutination test for identification of Staphylococcus aureus.

A new, commercially available latex agglutination test (SeroSTAT Staph; Scott Laboratories, Inc., Fiskeville, R.I.) was compared with the tube coagulase and slide coagulase tests as means for identifying Staphylococcus aureus. Of 160 clinical isolates of S. aureus, 159 (99.4%) yielded positive results with the latex agglutination test. Negative latex agglutination test results were obtained with 266 of 267 clinical isolates of Micrococcus spp. and staphylococcal species other than S. aureus (99.6%). The latex agglutination test was found to be a rapid, technically nondemanding method for identifying S. aureus. It was as accurate as the tube coagulase test and more accurate than the slide coagulase test.

Coagulase↗