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Biomedical subjects

R C Tilton

Publications and source records attributed to R C Tilton.

At least 37 records · Page 2Linked to original sources
PubMed1987

Clinical and ecological characteristics of Vibrio vulnificus in the northeastern United States.

Multiple seawater sites in the northeastern United States, particularly Long Island Sound, and shellfish from Long Island Sound were sampled from April to November for 3 successive yr, 1983-1985. Hospitals in coastal and metropolitan areas of Connecticut were surveyed for the same 3-yr period, Vibrio vulnificus can be found in these waters during the summer months. The appearance of these virulent bacteria in both seawater and shellfish are a function of the water temperature; no V. vulnificus could be isolated until the temperature was approximately 17 degrees C. Although the risk of infection is small, as shown by isolation of this organism from patients, certain high-risk groups exist. Consumption of raw shell fish during the summer months should be discouraged in people with liver disease or patients on immunosuppressive therapy.

Animals↗
PubMed1987

Collaborative clinical laboratory study of a broth-disk test for determination of bacterial susceptibility to beta-lactams in combination with amdinocillin.

Methodology for the performance of synergistic antibiotic susceptibility studies has not been standardized. We addressed this problem collaboratively with combinations of amdinocillin and select other beta-lactam antibiotics by using a simple broth-disk test compared with a microdilution approach. Each method used the same drugs singly and in combination. The broth-disk test evaluated each agent and the combinations at concentrations that reflected the breakpoints for each drug; the same ratios of beta-lactam to amdinocillin were used in doubling dilutions with the microdilution method. Initially, each participant studied the same 50 members of the family Enterobacteriaceae; each bacterium was studied on three occasions. Thereafter, 500 representatives of Enterobacteriaceae isolated recently from clinical specimens were studied. Designated strains served as controls. Reproducibility between the two approaches studied in phase 1 of the investigation indicated good agreement between the methods, ranging from 87 to 100%. Agreement between the microdilution and broth-disk tests for the 2,551 clinical isolates ranged from 86 to 95%, with slightly better correlations between combination results than with the single agents. The findings indicate that antibiotic disks used routinely in the clinical laboratory can be used in a simple elution test to determine susceptibility of organisms to beta-lactam antibiotics alone and in combination with amdinocillin.

Amdinocillin↗
PubMed1986

Rapid detection of Chlamydia trachomatis by an enzyme immunoassay method.

Chlamydia trachomatis has been shown to be a major cause of sexually transmitted diseases in the United States. An enzyme immunoassay (Abbot Laboratories) has been developed that detects chlamydial antigen directly in the urogenital specimens of patients. We have evaluated specimens from 1,074 patients belonging to one of three risk groups. Three swabs were collected from each patient--one each for Neisseria gonorrhoeae, chlamydia cell culture, and enzyme immunoassay. When compared with cell culture, the sensitivity and specificity of the enzyme immunoassay for symptomatic males and females attending a sexually transmitted disease clinic was 82% and 100%, and 91.3% and 95.0%, respectively. A moderate risk group, consisting of female patients seen at either urology or gynecology clinics for genitourinary symptoms was also evaluated. The sensitivity and specificity of the test on this group was 96% and 96.7%. A population of females at low risk were also screened for chlamydial infection. In this group, the sensitivity and specificity of the enzyme immunoassay was 89.3% and 93.2%, respectively. This rapid test is a highly specific and sensitive procedure for the detection of chlamydial antigen in genital specimens from high risk female patients as well as symptomatic males.

Antigens, Bacterial↗
PubMed1986

Infective endocarditis due to penicillin-tolerant Streptococcus bovis.

Two Streptococcus bovis isolates obtained from patients with endocarditis were found to be tolerant to penicillin and other cell wall active agents. By time-kill analysis, penicillin and streptomycin acted synergistically against these strains. The existence of tolerant S. bovis strains should be considered when initially choosing antibiotics for the treatment of serious S. bovis infections.

Adult↗
PubMed1986

Evaluation of rapid coagulase methods for the identification of Staphylococcus aureus.

Four rapid latex agglutination assays, StaphAurex (Wellcome Diagnostics, Research Triangle Park, N.C.), Bacto Staph (Difco Laboratories, Detroit, Mich.), SeroSTAT (Scott Laboratories, Inc., Fiskeville, R.I.), Veri-Staph (Zeus Technologies, Raritan, N.J.), and two hemagglutination tests, Staphyloslide (BBL Microbiology Systems, Cockeysville, Md.) and Hemastaph (Remel, Lenexa, Kans.), were compared with the conventional slide coagulase, tube coagulase (TC), and thermonuclease (TNase) tests for the identification of Staphylococcus aureus. A total of 118 clinical isolates of S. aureus (52 methicillin resistant), 50 S. epidermidis, 5 S. capitis, 2 S. hominis, 3 S. simulans, 6 S. saprophyticus, and 2 S. warneri were tested. The slide coagulase, TC and TNase tests detected 115 (97.5%), 117 (99.2%), and 118 (100%) of the S. aureus isolates, respectively. All showed 100% specificity. The StaphAurex, Veri-Staph, Staphyloslide, Hemastaph, SeroSTAT, and Bacto Staph assays correctly identified 117 (99.2%), 117 (99.2%), 116 (98.3%), 110 (93.2%), 108 (91.5%), and 107 (90.7%) of the S. aureus isolates, respectively. For methicillin-resistant S. aureus isolates, StaphAurex, Veri-Staph, Staphyloslide, Hemastaph, SeroSTAT, and Bacto Staph showed 1 (2%), 1 (2%), 2 (4%), 7 (13.5%), 7 (13.5%), and 8 (15.4%) false-negative results, respectively. All the commercial agglutination assays demonstrated false-positive results with strains of S. capitis, S. saprophyticus and S. warneri. The overall accuracy of the commercial agglutination assays compared with TC and TNase ranged from 90.7 to 99.2%. We recommend that negative reactions with the rapid commercial test kits for methicillin-resistant Staphylococcus isolates be confirmed with the TC or TNase test.

Agglutination Tests↗
PubMed1986

Candida detection system (CAND-TEC) to differentiate between Candida albicans colonization and disease.

Eighty-three serum specimens from 24 patients infected with Candida albicans were examined for circulating Candida protein antigens with the Candida Detection System (CAND-TEC; Ramco Laboratories, Inc., Houston, Tex.). The medical records of each patient were reviewed for clinical evidence of Candida colonization or disease, predisposing factors for infection, underlying illness, the presence of a contaminated indwelling venous catheter, intravenous amphotericin B therapy, and outcome. Forty-nine serum specimens with antigen titers of 1:2 or less were obtained either from colonized patients or at a time when disseminated disease was not yet clinically suspected. Except for five specimens from two colonized patients, one with a contaminated arterial line, the other specimens with titers of 1:8 or greater (n = 14) were obtained from patients who had been clinically diagnosed and treated for disseminated candidiasis. Serum specimens with titers of 1:4 were often from patients with deep-seated candidal infection but were not uniformly diagnostic; in this situation additional specimens should be tested for Candida antigen titers. Only 1 of 24 serum specimens from patients with no evidence of C. albicans infection had a Candida protein antigen titer of 1:8. With a 1:8 or greater titer as a criterion for dissemination, the sensitivity of the CAND-TEC system was 71%, with a specificity of 98%. If the 1:8 titer for the colonized patient with a contaminated arterial line is not considered a false-positive result, the CAND-TEC sensitivity was 83%. The latex agglutination assay appears to be a useful, rapid, and noninvasive means of laboratory diagnosis of systemic candidiasis. The recovery of C. albicans from at least three body sites may also be a useful predictor of disseminated disease.

Antigens, Fungal↗
PubMed1985

The aetiological agent of cat scratch disease.

A highly pleomorphic, gram-positive bacterium was cultured from an excised lymph node of a patient with cat scratch disease (CSD). The organism had morphological forms similar to those of the bacterium observed in Warthin-Starry stains of lymph node sections from CSD patients and may be the aetiological agent of this disease. Electron microscopic examination of lymph node sections from another patient with CSD showed organisms with morphological forms similar to those of the isolated bacterium. Biochemical and physiological analyses of this isolate suggested that it is not a commonly recognised contaminant or human pathogen and that it may be a member of the genus Rothia. This organism appears to resemble the bacterium that was identified as the aetiological agent of Parinaud's oculoglandular syndrome, a specific form of CSD, over 70 years ago.

Actinomycetaceae↗
PubMed1985

An assessment of available rapid immunologic diagnostic methods.

A critical evaluation of immunologic methods for diagnosis is presented. The issues of antibody versus antigen detection are addressed. Reverse capture immunoglobulin M detection is described as a potentially useful method. Agglutination procedures currently in use for antigen detection are summarized. Comparative evaluations of commercially available products are presented. The final issue discussed is that of enzyme immunoassay versus fluorescent antibody microscopy. Using Chlamydia detection as an example, advantages and disadvantages of each technology are assessed.

Agglutination↗
PubMed1985

Ciprofloxacin disk susceptibility tests: interpretive zone size standards for 5-microgram disks.

Evaluations of 5-microgram ciprofloxacin disk diffusion susceptibility tests were performed independently by seven different investigators. The results of the separate tests were combined to increase the number of resistant strains in the challenge set of microorganisms. Based on data with 2,652 isolates, the following interpretive breakpoints are tentatively proposed for use in ongoing clinical trials of ciprofloxacin: less than or equal to 15 mm, resistant (MIC greater than 2.0 micrograms/ml); 16 to 20 mm, intermediate (1.0 less than MIC less than or equal to 2.0 micrograms/ml); and greater than or equal to 21 mm, susceptible (MIC less than or equal to 1.0 micrograms/ml). Disk tests with Streptococcus spp. and with Pseudomonas maltophilia were not reliable; other microorganisms were accurately categorized by the disk diffusion test.

Acinetobacter↗
PubMed1985

Automated reading of MIC microdilution trays containing fluorogenic enzyme substrates with the Sensititre Autoreader.

The Sensititre Autoreader is a microcomputer-driven instrument capable of automatically reading antimicrobial susceptibility microdilution trays. The instrument measures the fluorescence liberated by bacterial enzymatic activity on fluorogenic substrates as an indicator of growth in each well. A mathematical algorithm converts the fluorescent signals from an antimicrobial dilution series to an MIC endpoint. A three-center study evaluated the performance of the Autoreader in comparison with MIC determined visually in a duplicate set of control plates lacking fluorogenic substrate. Among 828 isolates of gram-negative bacilli tested against 17 antimicrobial agents, Autoreader 18-h MIC were within +/- 1 twofold dilution of control MIC values (agreement) in 95.3% of instances. In 3.5% of the instances, Autoreader values occurred +/- 2 half-step dilutions from control values (minor discrepancy), and in only 1.2% of instances did Autoreader values deviate from control values by greater than +/- 2 dilution steps (major discrepancy). Agreement, minor discrepancies, and major discrepancies were noted among 148 gram-positive cocci tested against 11 antimicrobial agents in 93.5, 4.8, and 1.7% of the instances, respectively. Over half of the major discrepancies noted with gram-negative bacilli occurred with Proteus mirabilis-beta-lactam combinations, a problem that was resolved when a lower initial inoculum was used. Inter-and intralaboratory reproducibility was excellent. Standard Sensititre susceptibility trays may be instrument read at 18 h reproducibly and accurately with only slight modification of conventional procedures to include fluorogenic enzyme substrates in the incubation broth.

Anti-Bacterial Agents↗
PubMed1985

Comparison of the detection of herpes simplex virus in direct clinical specimens with herpes simplex virus-specific DNA probes and monoclonal antibodies.

A comparison of two commercially available kits for rapid herpes simplex virus (HSV) detection directly in patient specimens was performed. The immunofluorescence assay (IFA) utilized monoclonal antibodies to HSV, and the DNA probe assay utilized three HSV sequences cloned into pBR322. A sample of 243 specimens received in viral transport medium were inoculated into MRC-5 tissue cultures. The remainder of the specimen was centrifuged, and the cellular pellet was examined by IFA and DNA probes. One hundred and sixty-two (66.7%) specimens were considered satisfactory for IFA and DNA probe testing, based on a criterion of observing greater than or equal to 2 intact cells per high-power field. Of the 162 specimens, 35 (21.6%) yielded HSV by culture. By IFA, the sensitivity of detecting HSV culture-positive specimens was 77.1%; specificity was 100%, positive predictive value was 100%, and negative predictive value was 93.3%. DNA probe sensitivity was 71.4%; specificity was 90.6%; positive predictive value was 67.6%; and negative predictive value was 92%. Forty-four (27.2%) of the 162 specimens exhibited nonspecific cytoplasmic staining with the DNA probe. IFA and DNA probe assays can be completed in 2 to 3 h, whereas the average time to culture positivity in this series was 2.2 days. Rapid HSV diagnosis can aid in timely and appropriate patient management.

Antibodies, Monoclonal↗
PubMed1984

Rapid screening of urine for significant bacteriuria by Gram stain, acridine orange stain, and the Autobac MTS system.

Urine specimens submitted for microbiologic examination were screened for evidence of bacteriuria by three rapid methods: Gram staining, acridine orange staining, and the Autobac MTS system. The screening results were compared with those obtained by semiquantitative colony counts on agar plates. In this comparative study 1055 urine specimens were examined, of which 146 (13.8%) had colony counts of greater than or equal to 1 X 10(5)/ml. All three urine screening methods detected this level of bacteriuria at a sensitivity of 98% and a specificity of 55.2% (acridine orange), 66.0% (Gram stain), and 83.2% (Autobac), respectively. Of the 1055 urine specimens examined, 185 (17.5%) had colony counts of greater than or equal to 1 X 10(4)/ml, at which level the sensitivity of the three methods was 93% and the specificity was 56.7% (acridine orange), 68.0% (Gram stain), and 86.0% (Autobac), respectively. For any level of sensitivity, the Autobac urine screen was shown to be more specific than either the Gram stain or the acridine orange method. The acridine orange stain was the least specific urine screen, especially at the upper limits of sensitivity.

Acridine Orange↗
PubMed1984

Collaborative clinical evaluation of the Autobac IDX system for identification of gram-negative bacilli.

The Autobac IDX system (General Diagnostics, Warner-Lambert Co., Morris Plains, N.J.) for rapid, semiautomated identification of gram-negative bacilli was compared with the identification methods in routine use in four laboratories. The study included 1,515 organisms representing 30 species of enteric and nonenteric bacteria. Discrepancies between the results of the IDX system and routine methods were resolved by classical biochemical testing at a reference center. Overall, 98% of the organisms were correctly identified by the routine methods, and 93% were correctly identified by the IDX systems. After adjustment for frequency of clinical occurrence of the organisms tested, the IDX system performed with 95% accuracy. Results with the IDX system were available in 3 to 6 h. Results with the comparative methods were available in 4 to 48 h. A wide variety of organisms, including oxidase positive, oxidase negative, fermentative, and nonfermentative, were identified by a single system by using Autobac. Three or more systems were required to identify the 30 species by the comparative methods. Overall, the results indicate the Autobac IDX system is useful for the rapid identification of enteric and nonfermentative gram-negative bacilli.

Bacteriological Techniques↗
PubMed1984

Comparative evaluation of three commercial products and counterimmunoelectrophoresis for the detection of antigens in cerebrospinal fluid.

Three commercial products and counterimmunoelectrophoresis were evaluated for their ability to detect microbial antigens of Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae in cerebrospinal fluid from 157 patients suspected of having meningitis. Thirty-four patients were diagnosed as having bacterial meningitis by culture, microscopy, or antigen detection. The overall results showed the following detection percentages; counterimmunoelectrophoresis, 76%; Phadebact CSF, 76%; Directigen, 82%, and Bactigen, 93%. The results with purified antigen revealed that latex agglutination was more sensitive than coagglutination, which in turn was more sensitive than counterimmunoelectrophoresis.

Agglutination Tests↗
PubMed1984

Role of Chlamydia trachomatis in acute pharyngitis in young adults.

It has recently been suggested that Chlamydia trachomatis may be a common cause of acute pharyngitis in adults. In a prospective investigation of 95 college students with acute pharyngitis, C. trachomatis was not isolated from any pharyngeal cultures. Further investigations are needed to better define the role of C. trachomatis in upper respiratory tract infections.

Acute Disease↗
PubMed1983

Improved immunologic detection of Clostridium difficile antigen by counterimmunoelectrophoresis.

An improved counterimmunoelectrophoresis (CIE) procedure for detection of Clostridium difficile antigen is described. Commercially available antiserum to C. difficile toxin was absorbed with whole cells of C. difficile. CIE (absorbed) was 100% sensitive and 77.5% specific when compared to the tissue culture toxin assay. Instances are noted in which the CIE (absorbed) and/or bacterial culture was positive and the tissue culture assay was negative.

Antigens, Bacterial↗