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Biomedical subjects

A C Velasco

Publications and source records attributed to A C Velasco.

14 recordsLinked to original sources
PubMed1992

Evaluation of two commercial enzyme immunoassays for the diagnosis of Helicobacter pylori infection.

Sera from 65 patients with upper gastrointestinal tract symptoms and proven Helicobacter pylori infection, and from 42 negative controls were tested with two commercial EIAs (GAP test, BioRad; and ECP test, Biometra) and two non-commercial EIAs, one performed with whole sonicated cells and the other with acid extract of Helicobacter pylori as antigen. The GAP assay showed a sensitivity of 83.1% and a specificity of 47.6%. The ECP assay showed a sensitivity of 87.7% and a specificity of 61.9%. For both non-commercial EIAs these figures were 87.7% and 88.1%, respectively. Independent of the interpretive criteria established by the manufacturers, receiver operating characteristic curves were plotted for better evaluation of the four methods. Both commercial tests showed a lower probability of yielding a correct diagnosis than the non-commercial tests (p less than 0.05). Although commercial EIAs are convenient for the diagnosis of Helicobacter pylori infection, the accuracy of the two commercial tests evaluated in this study was lower compared to that of the two non-commercial EIAs.

Adult↗
PubMed1990

Rapid fluorescence method for screening Salmonella spp. from enteric differential agars.

Four hundred thirty-two lactose-negative colonies isolated from human feces on stool differential agar media were flooded with one drop of MUCAP Test reagent (Biolife Italiana S.r.I., Milan, Italy) and observed under a Wood lamp for the development of a blue fluorescence over or around the colony. On the basis of manual and automated conventional tests for the screening of Salmonella spp., the MUCAP Test yielded the following results: 79 true-positives, 314 true-negatives, 35 false-positives, and 4 false-negatives (sensitivity, 95%; specificity, 90%; positive predictive value, 69%; negative predictive value, 99%). The specificity of the test performed on colonies isolated on MacConkey agar (95%) was higher than that performed on colonies isolated on SS agar (88%; P less than 0.03). The MUCAP Test is an easy, rapid, and sensitive method for the screening of colonies suspected of being Salmonella spp., reducing the number of biochemical tests needed.

Agar↗
PubMed1989

Recovery of Campylobacter from human faeces stored at 4 degrees C.

Six hundred and thirteen fresh diarrhoeal faeces were inoculated on Skirrow blood agar (SK), on Preston blood free agar (PBF), and in Campy-thioglycolate broth (CT). After 24 h of storage at 4 degrees C, specimens were again inoculated on SK and PBF, and in Campylobacter enrichment broth (CEB). CT tubes were placed overnight at 4 degrees C. Plates and CEB tubes were incubated at 43 degrees C in microaerophilic conditions. A total of 68 specimens was positive for campylobacter on direct plating. Sixty-four of them were also recovered after subculturing from CT, and only 51 from CEB. Delayed inoculation of plates after storage of samples at 4 degrees C yielded 57 isolates. The storage of faeces at 4 degrees C for 24 h significantly reduces the number of campylobacter isolates. When samples are not plated immediately we recommend inoculating a CT tube maintained at 4 degrees C overnight as a holding medium.

Campylobacter↗
PubMed1989

Evaluation of a disk method for detection of hippurate hydrolysis by Campylobacter spp.

A disk method for detecting hippurate hydrolysis by Campylobacter spp. was evaluated and compared with the conventional tube test used at the Centers for Disease Control (CDC) (G.K. Morris and C.M. Patton, p. 302-308, in E.H. Lennette, A. Balows, W.J. Hausler, Jr., and H.J. Shadomy, ed., Manual of Clinical Microbiology, 4th ed., 1985) and high-performance liquid chromatography (HPLC). A total of 118 Campylobacter strains were tested. Eighty-seven strains (74%) were hippurate positive by the HPLC method, and the remaining 31 (26%) were found to be hippurate negative. By using HPLC as the reference technique, the CDC method showed a sensitivity of 80% and a specificity of 81%; the disk method showed a sensitivity of 93% and a specificity of 94%. The disk method can be performed with a small inoculum of bacteria, did not present problems of interpretation, and showed better results than the CDC method (P = 0.015).

Bacteriological Techniques↗
PubMed1989

[Clinical and epidemiologic characteristics of diarrhea caused by Cryptosporidium].

During a 28 month period, 6336 fecal samples from 5845 inpatients or outpatients with acute gastroenteritis were studied; 850 samples from individuals without diarrhea were evaluated as controls. Cryptosporidium oocysts were stained with a technique for acid-alcohol resistance, and the parasite was found in 40 patients with diarrhea (0.7%) and in one healthy control (0.1%). All patients had diarrhea at the time of diagnosis; abdominal pain and vomit were less common. All patients except two were below ten years of age. There were no definite seasonal differences in the incidence of Cryptosporidium diarrhea although there was a small predominance in the last summer and initial autumn months. Three patients required spiramycin therapy; the diarrhea disappeared in all cases.

Adolescent↗
PubMed1987

Enzyme-linked immunosorbent assay for diagnosis of brucellosis.

The performance of an ELISA for detection of total antibodies to Brucella spp. was compared with that of the Rose Bengal, standard agglutination and Coombs test in the diagnosis of brucellosis. Sera tested were from 208 patients from whom Brucella melitensis had been isolated, 177 patients with significant results in at least two conventional tests, and 107 patients with fever from whom no Brucella spp. had been isolated and in whom all conventional tests were negative. ELISA was the most sensitive test (97%), showing greater specificity (96%) and good predictive positive and negative values (98% and 94% respectively). ELISA was the only positive test in 6% of patients in whom brucellosis had been confirmed by culture.

Agglutination Tests↗
PubMed1987

Evaluation of four enrichment media for isolation of Campylobacter jejuni.

Diarrheal stool specimens were inoculated into the following media: alkaline peptone water (APW), Bruce-Zochowsky medium (BZ), Campylobacter enrichment broth (CEB), Campy-thio broth (CT), and Skirrow blood-agar (SK) plate. All media were incubated at 42 degrees C in microaerophilic conditions for 24 h. Afterwards, a new SK plate was inoculated from every liquid medium. Campylobacter jejuni was isolated from 43 of the 259 specimens when CT was used, from 45 when APW was used, from 46 when BZ was used, and from 46 when CEB was used; these totals include specimens that grew after enrichment only, on SK plates only, and both after enrichment and on SK plates. No significant differences were found between the isolates obtained with and without enrichment procedures.

Campylobacter fetus↗
PubMed1987

Rapid automated method for screening of enteric pathogens from stool specimens.

A total of 800 colonies suggestive of Salmonella, Shigella, or Yersinia species isolated on stool differential agar media were inoculated onto both conventional biochemical test media (triple sugar iron agar, urea agar, and phenylalanine agar) and Entero Pathogen Screen cards of the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Based on the conventional tests, the AutoMicrobic system method yielded the following results: 587 true-negatives, 185 true-positives, 2 false-negatives, and 26 false-positives (sensitivity, 99%; specificity, 96%). Both true-positive and true-negative results were achieved considerably earlier than false results (P less than 0.001). The Entero Pathogen Screen card method is a fast, easy, and sensitive method for screening for Salmonella, Shigella, or Yersinia species. The impossibility of screening for oxidase-positive pathogens is a minor disadvantage of this method.

Bacteriological Techniques↗
PubMed1986

Comparative efficacy of seven selective media for isolating Campylobacter jejuni.

Diarrheal stools from 263 patients were inoculated on seven selective media: Butzler selective medium, Blaser medium, Skirrow blood agar, Preston campylobacter selective medium, Preston campylobacter blood-free medium, Butzler Virion medium, and modified Preston medium (with amphotericin B [2 mg/liter]). A similar number of Campylobacter jejuni strains were isolated from all the media studied; nevertheless, the presence of competing fecal flora (FF) made the detection of suspect colonies difficult. Preston campylobacter blood-free medium with cefoperazone yielded the greatest number of C. jejuni isolations, and contaminating FF grew in only 9% of the plates showing C. jejuni growth; all the other media allowed the abundant growth of other FF, regardless of whether C. jejuni was isolated from them or not.

Campylobacter fetus↗
PubMed1984

Three-year prospective study of intestinal pathogens in Madrid, Spain.

During the period July 1980 through June 1983, in a General Hospital in Madrid, the following organisms were detected from 6,970 patients with gastroenteritis: 710 Salmonella spp. 506 Campylobacter jejuni, 379 Shigella spp., 12 Yersinia enterocolitica, 1,466 rotavirus, 134 Giardia lamblia, and 4 Entamoeba histolytica. Chloramphenicol showed good activity against most tested strains of Salmonella spp., Shigella spp., and C. jejuni. The incidence of Salmonella spp. and Shigella spp. was very marked in the hot dry months of the year, rotavirus predominated during the cold months, and no seasonal variations of importance were seen for C. jejuni and G. lamblia.

Anti-Bacterial Agents↗
PubMed1981

[Campylobacter neonatal enteritis (author's transl)].

Authors communicate four cases of bloody diarrhea in neonates, with Campylobacter fetus jejuni in the stools. In one case, the same bacteria was isolated from the mother and, in another case, existed possibility of a cross-infection. The mildness of the evolution is marked, specially in those cases in which maternal feeding was continued. Some diagnostic and epidemiological aspects, concerning the neonatal period, are commented.

Campylobacter Infections↗