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Biomedical subjects

R C Tilton

Publications and source records attributed to R C Tilton.

At least 55 records · Page 3Linked to original sources

Identification of Legionella pneumophila by latex agglutination.

A latex agglutination test for the identification of Legionella pneumophila serogroups 1 through 6 is described. The reagent is specific for L. pneumophila and enables the ready identification of L. pneumophila colonies on agar plates. Preliminary evidence suggests that latex agglutination enables the detection of soluble L. pneumophila antigens in respiratory secretions of patients suspected of having legionellosis.

Antigens, Bacterial↗

Rapid quantitative microenzyme-linked immunosorbent assay for tetanus antibodies.

A rapid quantitative microenzyme-linked immunosorbent assay for the detection of immunoglobulin G antibodies to tetanus toxoid is described. The assay is performed in 2.5 h and detects antibody levels of between 0.1 and 6 U/ml. Quantitation of the antibody concentration is unique in that multiple serum dilutions are tested on a single patient, the results are plotted as an antibody dilution curve, and the area under the curve is integrated for a final concentration. Tests for immune status on sera from 77 individuals demonstrated tetanus antibody concentrations of greater than or equal to 0.1 U/ml in 92% of a pediatric group and 62% of an adult group. The microenzyme-linked immunosorbent assay procedure is reproducible and is useful for the determination of immune status and immunization response.

Adult↗

Pseudomonas whirlpool dermatitis. Report of an outbreak in two families.

Pseudomonas aeruginosa skin infections developed in four children and their parents after use of a recreational whirlpool. These patients were carefully followed throughout the course of their illnesses. The incubation period was two to five days. The skin lesions included erythematous macules and papules, pustules, and nodules. The severity of the illness varied from a few scattered pustules in one patient to an extensive truncal rash, malaise, and fever in another patient. P. aeruginosa was recovered from skin lesions and the whirlpool water. Gram stains from two patients revealed polymorphonuclear leukocytes and gram-negative rods. In all patients, the rash improved within seven days and local application of povidone-iodine did not appear beneficial.

Adolescent↗

Methodological variation in antibiotic synergy tests against enterococci.

Thirty-two human isolates of enterococci were tested for antibiotic synergy by using penicillin and one of six aminoglycosides. Three methods were used: synergy screen, microdilution checkerboard, and time-kill curves. The synergy screen accurately predicted synergy for gentamicin-penicillin combinations, and this synergy was later confirmed by time-kill curves. The microdilution checkerboard method suffered from inherent variation, and agreement with time-kill curves ranged from 92% (twofold reduction in minimum inhibitory concentration) to 4.2% (fourfold reduction in minimum inhibitory concentration). We suggest that enterococci be screened for synergy (i.e., presence or absence of high-level resistance) by using the criterion of growth or no growth in the presence of 2,000 microgram of an aminoglycoside per ml. The microdilution checkerboard test for synergy is not recommended.

Aminoglycosides↗

Toxigenic Clostridium perfringens from a parvovirus-infected dog.

A strain of Clostridium perfringens, type A, has been isolated from the intestine of a dog which died from parvovirus infection. This Clostridium strain produces a toxin which can be detected by counterimmunoelectrophoresis, using C. difficile antitoxin, and produces cytotoxicity in WI-38 cell culture. Cytopathology can be blocked by C. difficile antitoxin. Its role in canine parvovirus infection is unknown.

Animals↗

Automated direct antimicrobial susceptibility testing of microscopically screened urine cultures.

Two screening methods for urine microbiology are proposed: one in which the Gram-stained smear is used to detect significant bacteriuria, and another in which Autobac antibiotic susceptibility tests are performed directly on positive urine samples. Results on 1,350 specimens indicated that an average of 18 bacteria per oil immersion field were observed in the urine of patients with significant bacteriuria, and an average of less than 1 bacterium per oil immersion field was found in the urine of patients without significant bacteriuria. Direct susceptibility testing by Autobac proved to be rapid (3 h versus 24 h) and reliable (0.5 to 1.2% discrepancies).

Anti-Bacterial Agents↗

Rapid detection of Clostridium difficile toxin in human feces.

Fifty fecal specimens were tested by three methods, bacterial isolation, counterimmunoelectrophoresis, and tissue culture, for Clostridium difficile and its toxin. Ten specimens (20%) were positive by all three methods. An additional eight specimens were toxin positive only by counterimmunoelectrophoresis. Although counterimmunoelectrophoresis and tissue culture are of equivalent sensitivity, the additional dilution necessary for tissue culture assay may be critical when only small concentrations of toxin are present.

Bacterial Toxins↗

Clinical and laboratory evaluation of the antibody-coated bacteria test in children.

The antibody-coated bacteria test can distinguish upper from lower urinary tract infection. In this study 67 bacteriuric children were selected from meningomyelocele and urology clinics. There was close correlation between radiological evidence of upper tract changes and the presence of antibody-coated bacteria. There was a distinct lack of correlation between serum antibody titers to the infecting organism and antibody-coated bacteria. In vitro laboratory studies indicated that 1) antibody coating in the urine occurred immediately upon exposure of the infecting isolate to the urine of the patient, 2) only the homologous isolate was coated and 3) the pH range for antibody coating was wide (pH 4.0 to 9.0).

Adolescent↗

Release of rhodanese from Pseudomonas aeruginosa by cold shock and its localization within the cell.

Whole cells of Pseudomonas aeruginosa possess rhodanese activity. The enzyme can be released by rapidly resuspending the cells in cold Tris--HCl buffer. Approximately 95% of the rhodanese activity is released by cold shock. Release of the enzyme can be inhibited either by preincubating the cells with Mg2+ or by incorporating Mg2+ into the shocking buffer. The effect of Mg2+ can be reversed by washing the cells twice with buffer prior to cold shock. While rhodanese can be released from P. aeruginosa by cold shock, lactic dehydrogenase, a cytoplasmic enzyme, remains within the cell. Diazo-7-amino-1,3-napthalenedisulfonic acid, a compound which does not penetrate the cytoplasmic membrane, completely inactivated rhodanese and alkaline phosphatase, a periplasmic enzyme, whereas lactic dehydrogenase retained its full activity. These data suggest that rhodanese in P. aeruginosa, like alkaline phosphatase, is located distal to the cytoplasmic membrane in the periplasmic space. Electron micrographs also show that portions of the lipopolysaccharide outer membrane are shed from the cell during cold shock, while cells preincubated with Mg2+ did not release segments of their outer membrane.

Alkaline Phosphatase↗

Legionnaires' disease antigen detected by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay method has been developed for the rapid detection of antigen from clinical specimens such as urine and sputum. Preliminary evidence suggests that the antigen is present and can be detected in the sputum and possibly urine of patients with Legionnaires' disease. Patients not harboring the Legionnaires' disease bacterium have been uniformly negative to date.

Antigens, Bacterial↗

Susceptibilities of Pseudomonas species to tetracycline, minocycline, gentamicin, and tobramycin.

Members of the genus Pseudomonas are widely implicated in human disease. Although most isolates are P. aeruginosa, there have been serious outbreaks of infection with other members of the genus. The susceptibility patterns of 5) Pseudomonas isolates are reported. It was notable that of the four antibiotics tested, uniform susceptibility was observed with minocycline.

Anti-Bacterial Agents↗

Reversal of the silver inhibition of microorganisms by agar.

Increasing use of silver in the treatment of water has necessitated an examination of microbiological methods for the measurement of silver inactivation of microorganisms. Three common agar media were tested for their ability to neutralize the bacteriostatic effects of silver. Results suggested that growth media differed in their neutralizing capacity; that is, the non-inhibitory media tryptone glucose agar and Trypticase soy agar showed more neutralizing capacity than eosin methylene blue agar. Furthermore, the neutralizing effect appeared to be a function of the soluble component of the media and not of the agar itself.

Agar↗