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Recent recommendations for the serological diagnosis of Lyme disease include statements on quality assurance and the use of performance panels to assess laboratory competency. We used two performance panels--one from the Centers for Disease Control and Prevention (CDC) and one from Boston Biomedica Inc. (West Bridgewater, MA)-to evaluate the sensitivity and specificity of four western blot kits. We used the same panels to compare the interpretive criteria for western blots as proposed by participants in the Centers for Disease Control and Prevention, Association of State and Territorial Public Health Laboratory Directors Conference and those proposed by BBI Clinical Laboratories (BBICL; New Britain, CT). Our results indicated that the BBICL western blots were more sensitive than those of the CDC, MarDx (Carlsbad, CA), or Cambridge Biotech (Rockville, MD). However, use of the CDC criteria with the BBICL western blots increased specificity to 100% but reduced sensitivity to 74.3%. A sample table is provided as an example of the test results obtained with the BBI performance panel. Obviously, this work should be confirmed by other investigators.

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Bordetella pertussis was transmitted from an immunized boy to his father and possibly to other family members. This case report demonstrates that although unusual, acute adult B. pertussis infection can occur. B. pertussis immunization may not prevent infection but can reduce the severity. B. pertussis was detected in sputum from the adult by direct-fluorescent antibody staining and was grown on Regan-Lowe medium. Serology tests confirmed the infection in the adult.

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OBJECTIVES: To assess the reliability of the Monolert test, a new enzyme-linked immunosorbent assay for the diagnosis of acute infectious mononucleosis (IM). DESIGN: A retrospective laboratory and clinical analysis of 38 children diagnosed with acute IM. SETTING: A suburban pediatric practice in Connecticut. PATIENTS: Thirty-eight children (ages 18 months to 17 years) who were diagnosed with acute IM using the Monolert test during the period October 1992 to August 1993. RESULTS: Eighty-three percent of these children had no evidence of Epstein-Barr virus infection on subsequent investigation. The false positive results of the Monolert test could not be explained on the basis of elevated antibody titers to either cytomegalovirus or Borrelia burgdorferi. CONCLUSION: Monolert is a poor screening test and is of little apparent value as a diagnostic test for acute Epstein-Barr virus infection in pediatric patients.

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Over 2800 clinical strains of the Bacteroides fragilis group were collected during a 5-year period from ten geographically separate sites and tested for their susceptibility to various antimicrobial agents using a broth microdilution method. Among the cephalosporins, ceftizoxime was the most active (13% resistance) and importantly exhibited relatively equal activity against both B. fragilis species and non-B. fragilis species. Cefotaxime exhibited similar activity with an overall resistance rate of 18%. Both ceftriaxone and cefoperazone were appreciably less active cephalosporins especially against non-B. fragilis species. With regard to cephamycins, cefoxitin (MIC90, 32 micrograms/ml) was more active than cefotetan (MIC90, > or = 256 micrograms/ml) and cefmetazole (MIC90, 64 micrograms/ml). Non-B. fragilis species were highly resistant to cefotetan and cefmetazole. Imipenem was highly active against all strains with the exception of four strains of B. fragilis. Ampicillin-sulbactam, amoxicillin-clavulanate, piperacillin-tazobactam, and cefoperazone-sulbactam were all highly active with resistance rates < 2%. No resistance was detected to metronidazole, whereas 14% of isolates were resistant to clindamycin. When compared with other studies, these findings underscore the wide variability in susceptibility patterns reported nationwide and the need to continue monitoring these patterns to aid in choosing the most active compounds for therapy.

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BACKGROUND AND OBJECTIVES: Single dose regimens have advantages in the treatment of STD. Azithromycin has unique pharmacokinetics that may make single dose regimens feasible. Treatment with a single 1 g dose of azithromycin was compared to 100 mg doxycycline twice daily for seven days. STUDY DESIGN: This was a randomized third-party blinded study on 183 male patients, 176 of whom could be evaluated for efficacy. RESULTS: Chlamydia trachomatis was cultured from 148 patients, 79 receiving azithromycin and 69 receiving doxycycline. Six patients receiving azithromycin had positive cultures on follow-up, four were known to have had sexual intercourse with infected partners. Fifty-one patients had gonorrhea; 28 were treated with azithromycin and 23 with doxycycline. Neisseria gonorrhoeae was eradicated from all patients except one receiving azithromycin. He denied sexual exposure during follow-up. Sixty patients were infected with Ureaplasma urealyticum, 35 were treated with azithromycin and 25 with doxycycline. Five patients in each group had positive cultures on follow up. Three patients receiving azithromycin and two receiving doxycycline were known to have had sexual exposure during follow-up. CONCLUSION: A single dose of azithromycin showed similar effectiveness as a 7-day regimen of doxycycline.

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A multicenter trial of the Sensititre AP80 panel read on the Sensititre AutoReader (Radiometer America, Westlake, Ohio) for the automated identification of gram-negative bacilli was conducted with 1,023 clinical isolates (879 members of the family Enterobacteriaceae plus 144 nonenteric organisms). Assignment of taxa was based on the computer-assisted interpretation of the results of a series of reactions with fluorogenic enzyme substrates after 5 h of incubation, with an incubation interval of approximately 18 h used when indicated. Accuracy was determined initially by comparison with the results obtained with the API 20E or Rapid NFT system (Analytab Products, Plainview, N.Y.). Isolates showing discrepancies were identified by using conventional biochemical profiles. Identifications were available after 5 h of incubation for 918 isolates (90%). Agreements with reference results for members of the family Enterobacteriaceae were 95.3 and 92.5% at the genus and species levels, respectively, and for the nonmembers of the family Enterobacteriaceae, the agreements with reference results were 95.1 and 84.7%, respectively. The Sensititre AP80 panel was found to be simple and convenient to use, allowed for the testing of three isolates per panel, required minimal supplementary testing for completion of identification, performed in a reproducible fashion, and demonstrated an accuracy of same-day identification comparable to that reported for other automated systems. The AP80 panel appears well suited for routine use in the clinical microbiology laboratory as an automated means of identifying both members of the family Enterobacteriaceae and nonenteric gram-negative bacilli.

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OBJECTIVE: To estimate seroprevalence of antibodies to hepatitis C virus in healthcare workers at high risk for blood exposure. DESIGN: A prospective anonymous seroprevalence survey of 243 healthcare workers. SETTING: A large referral hospital and 2 community hospitals in Connecticut. PARTICIPANTS: Healthcare workers, including surgical personnel, dentists, hemodialysis workers, laboratory workers, and emergency room staff. RESULTS: Antibody to hepatitis C virus was found in 1.6% (95% confidence interval [CI95] = 0-3.2%) of healthcare workers. None of the prevalent seropositives had a past history of clinical hepatitis or blood transfusion. CONCLUSIONS: We conclude that the seroprevalence of hepatitis C virus in healthcare workers with a high degree of blood exposure is low and is similar to seroprevalence rates reported for volunteer blood donors. However, first-generation hepatitis C serologic tests may underestimate the true prevalence of infection. Further studies, including prospective cohort studies, will be required to determine if the low seroprevalence is from low risk of acquisition of disease or from loss of measurable humoral antibody response to the virus.

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One hundred and eighty-two patients were enrolled in a randomized third-party blinded study to assess the efficacy and safety of azithromycin in the treatment of sexually transmitted diseases. Three regimens of azithromycin, including a single oral dose, were compared with a standard treatment with doxycycline. The patients were followed for four weeks. Efficacy was evaluated in 168 patients (113 azithromycin, 55 doxycycline). Fourteen patients had negative cultures or did not come for all follow-up visits. Of the 168, 138 were infected with Chlamydia trachomatis, 43 with Neisseria gonorrhoeae, and 45 with Ureaplasma urealyticum. Ninety-six per cent of patients with chlamydial infections and 92% of those with gonorrhoea were cured with azithromycin. Two patients infected with N. gonorrhoeae, four with C. trachomatis and six with U. urealyticum had positive cultures on follow-up visits after receiving azithromycin. Of these 11 patients with positive cultures on follow-up visits, seven (five with U. urealyticum and two with C. trachomatis) violated the protocol by having intercourse with infected individuals during the study. Azithromycin was very well tolerated; one patient complained of mild abdominal pain shortly after receiving the drug, seven patients complained of mild nausea and two patients had mild diarrhoea.

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In summary, there are a variety of methods for the rapid detection of bacteria, only a few of which have been covered in this essay. However, 3 points must be made: 1) The availability of a test for antigen detection does not guarantee its clinical relevance. 2) More attention must be paid to the statistical relevance of tests for bacterial detection. 3) The advantages of a rapid test compared to a very lengthy traditional test for bacterial detection may not be obvious unless there is an organized method of education and accompanying justification, such as treatment efficacy, for the use of this new test.

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Eighty human serum specimens tested concomitantly by immunoblot and an enzyme-linked immunosorbent assay developed jointly at the University of Connecticut School of Medicine and the Connecticut Agricultural Experiment Station were used to evaluate three commercially available diagnostic products for Lyme borreliosis. The sources of the kits were Hillcrest Biologicals, Cypress, Calif.; Whittaker Bioproducts, Walkersville, Md.; and Cambridge Bioscience, Worcester, Mass. When compared with Western blot analysis, the sensitivities and specificities, respectively, for the diagnostic assays were as follows: Hillcrest Biologicals, 93 and 75%; Whittaker Bioproducts, 73 and 100%; Cambridge Bioscience, 89 and 100%; and University of Connecticut School of Medicine, 96 and 92%.

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The laboratory diagnosis of Mycoplasma pneumoniae is often difficult because of lengthy and complicated cultural methods and serological tests that may be both insensitive and nonspecific. In this study, 82 patients suspected of Mycoplasma pneumonia were cultured for M. pneumoniae, and their respiratory secretions were tested by a DNA probe for M. pneumoniae. The probe test was 100% sensitive and 98% specific compared to culture. This DNA probe, then, is an effective alternative method for the detection of M. pneumoniae in respiratory specimens.

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Four hundred and seventy-three men and women at high risk for sexually transmitted disease were tested for the presence of Chlamydia trachomatis in the urethra or the endocervix. Four groups were involved in this multicenter study of two direct fluorescent-antibody microscopy tests, Kallestad Pathfinder and Syva Microtrak, compared with culture techniques. Results from the test sites indicated that there was no significant difference overall in the sensitivity and specificity of the two test kits. However, there was some interlaboratory variation seen in the sensitivity of the microscopy, but little difference in the specificity. Either kit could be an effective screening method for C. trachomatis in high-risk populations.

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Infectious mononucleosis (IM) is caused by the Epstein-Barr virus. Commonly used laboratory tests used for diagnosis of IM include a screening test based on the observation that horse erythrocytes are agglutinated by the Paul-Bunnell antibody found in the serum of patients with IM. This study evaluated two latex agglutination (LA) kits for IM, Monolatex (Wampole Laboratories) and Immunoscan-IM (American MicroScan) (formerly Monogen; Biokit, S.A.), and compared them with Monospot (Ortho Diagnostic Systems) results on 220 patient sera. Discrepancies in the three test results were resolved with complete Epstein-Barr virus antibody profiles. They indicated that any of the three kits tested can be successfully used as a screening test for IM. The advantage of the LA kits is that no differential absorption step is necessary. When discrepancies were resolved, sensitivity and specificity of both LA kits were greater than 93%.

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Automated microdilution MIC results, obtained with the Autoreader (Sensititre, Inc., Salem, N.H.) following 5 h of incubation, were compared with manually read, concurrent control MICs following 18 h of incubation in a three-laboratory comparative study. A total of 704 members of the family Enterobacteriaceae or similar gram-negative organisms were tested against 17 antimicrobial agents. Autoreader MICs were within 1 doubling dilution of control values in 92.9% of instances. Discrepancies of +/- 2 doubling dilutions and +/- 3 or greater doubling dilutions were noted in 4.5 and 2.6%, respectively, of the 7,687 drug-organism combinations analyzed. The majority of errors occurred when beta-lactam antimicrobial agents were tested with a variety of different species. MICs at 5 h, when Pseudomonas aeruginosa was used, were possible in only half the isolates tested and yielded data on only a limited number of drugs in the remaining instances. Excluding results obtained with penicillin and ampicillin, which were uniformly poor, Staphylococcus aureus Autoreader values were within +/- 1 doubling dilution of control values in 93.6% of instances, 5.4% varied by +/- 2 dilutions, and only 1% of test values by +/- 3 or more dilutions from control values for 82 isolates tested against nine antimicrobial agents. Of eight additional S. aureus isolates tested that were resistant to methicillin, only one was read correctly by the Autoreader, with results on the remaining seven appearing as either insufficient growth or as total resistance to all drugs tested. Interlaboratory reproducibility was excellent for selected isolates of S. aureus and gram-negative bacilli. The accuracy of the Sensititre Autoreader MIC results was comparable to that of other same-day quantitative systems for members of the family Enterobacteriaceae and S. aureus, while the economic and procedural advantages of the broth microdilution method was maintained.

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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.

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Currently, the method of choice for the laboratory diagnosis of Clostridium difficile disease is the detection of cytotoxin in stool filtrates by tissue culture. Since many hospital laboratories do not have tissue culture facilities, there is a need for a rapid test which is both sensitive and specific to diagnose C. difficile disease. A commercial latex agglutination was compared with the conventional cytotoxin tissue culture assay for the detection of C. difficile or its toxin(s) in fecal specimens. Of the 574 specimens evaluated, 111 were cytotoxin positive while 97 were positive by the latex agglutination test. There were 17 specimens positive by latex agglutination but negative by tissue culture assay. The overall sensitivity and specificity of the CDT latex test was 86.1 percent and 95.3 percent respectively. This rapid latex test can serve as an excellent screening procedure for the presence of C. difficile. Those specimens positive by the latex test should be further evaluated for the presence of cytotoxin by tissue culture.

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In a group of children with acute, nonstreptococcal pharyngitis, only one (2%) of the 44 children tested showed serologic or direct-immunofluorescence evidence of a recent Chlamydia trachomatis infection. Only two (5%) of the 43 children tested showed serologic evidence of a recent Mycoplasma pneumoniae infection. Neither C. trachomatis nor M. pneumoniae appears to be an important cause of acute pharyngitis in children.

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