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Human babesiosis was first recognized in Connecticut in 1989, nearly 15 years after Lyme disease, a similarly transmitted spirochetosis, was detected in the state. To determine the seroprevalence for the babesial pathogen and whether it was recently introduced, we used an indirect immunofluorescence assay to test for Babesia microti antibody in 1,285 Connecticut residents. Four groups were studied: I, people seropositive for Lyme disease, tested from 1986 to 1989; II, randomly selected outpatients tested in 1989; III, college students residing in Connecticut, tested from 1959 to 1989; and IV, healthy people without tick exposure or Lyme disease, tested in 1989. Babesia seropositivity was significantly higher in group I (9.5%; n = 735) than in groups II (2.6%; n = 304, P less than 0.0001) and III (1.0%; n = 206, P less than 0.0001) but not group IV (2.5%, n = 40). Babesia seropositivity for group I ranged from 9.2 to 10.2% between 1986 and 1989, and Babesia seropositivity for group III ranged from 0% between 1959 and 1985 to 2.9% between 1986 and 1989. There is a considerable risk of babesial infection among residents of the Connecticut mainland who are seropositive for Lyme disease, a risk that appears to have remained constant over the past 5 years.

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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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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.

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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.

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Forty-five isolates of gentamicin resistant Pseudomonas aeruginosa were evaluated for gentamicin-carbenicillin synergy. Only 9 percent (4/45) showed synergy. Of nine isolates with demonstrable zones around a gentamicin disc (8 to 12 mm), none showed a synergistic response. Effective treatment of gentamicin resistant Ps. aeruginosa with gentamicin and carbenicillin should not be assumed without additional test procedures.

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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.

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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.

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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.

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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).

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A method is described for the rapid, simultaneous determination of the MIC's of chloramphenicol and ampicillin to Haemophilus influenzae. Excellent agreement was observed between the Autobac method and the agar dilution method for antimicrobial susceptibility. All ampicillin resistant Haemophilus isolates produced beta lactamase and none of the suceptible strains produced this enzyme.

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