Detection of group B streptococcal antigen in body fluids by a latex-coupled monoclonal antibody assay

Rench, Marcia A.; Metzger, T G; Baker, Carol J.

doi:10.1128/jcm.20.5.852-854.1984

Cited by 25 publications

(4 citation statements)

References 10 publications

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“…The LA kits, which have replaced counterimmune electrophoresis, are in many ways ideal assays. They have the potential advantages of being rapid, technologically straightforward, specific, sensitive for detection of nanogram quantities of antigen, and positive despite prior antimicrobial therapy (1,2,8,9,10,13,16,20,30,37,39,41,42,45). Additionally, urine can be used as the sample material, with the advantage that it is simple to collect and contains bacterial antigens concentrated 10-to 50-fold over those found in serum (1).…”

Section: Discussionmentioning

confidence: 99%

Rapid bacterial antigen detection is not clinically useful

1995

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Latex agglutination (LA) of capsular polysaccharide bacterial antigen is a frequently performed laboratory procedure, but its use is controversial. To assess the clinical utility of this test, we reviewed all LA tests performed over a 10-month period at two sites, a major university-based referral center and a private specialty pediatric hospital. Samples were assayed either individually or as a panel for the group B streptococcus, Streptococcus pneumoniae, Haemophilus influenzae, and three sets of Neisseria meningitidis serogroups (A and Y, C and W135, and B and Escherichia coli K1). Of 5,169 assays performed on 1,268 clinical samples (786 urine and 478 cerebrospinal fluid, 3 pleural fluid, and 1 synovial fluid sample), 57 (1.1%) were positive, including 1.7% of urine and 0.3% of cerebrospinal fluid samples. All LA true-positive cerebrospinal fluid samples showed the causative microorganisms by Gram stain. Detailed chart review of these 57 positive samples showed that the LA result was false-positive in 31 (54%), true-positive in 22 (38%), and indeterminate in 4 (7%) samples. Therapy was not altered on the basis of any of the true-positive LA results. The 31 false-positive results led to additional cost, prolonged hospitalization, and some clinical complications. Total patient charges were $175,000 ($7,954 per true-positive), with no detectable clinical benefit. Our retrospective study does not support the current use of LA for rapid antigen detection. What, if any, specific indications exist for this test remain to be elucidated.

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Section: Discussionmentioning

confidence: 99%

Rapid bacterial antigen detection is not clinically useful

1995

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“…Many of the original studies evaluating the sensitivities of the LPA tests used concentrated urine as the preferred body fluid for evaluation (4,7,9,11,15,17,23,26). When compared directly, the testing of concentrated urine was more sensitive than that of unconcentrated urine in those studies (9,11,23,25). However, in clinical practice urine is frequently not concentrated prior to testing (6), despite the recommendations of several of the manufacturers, probably because of the added cost and time required.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity and specificity of rapid diagnostic tests for detection of group B streptococcal antigen in bacteremic neonates

Greenberg

Ascher²,

Yoder³

et al. 1995

J Clin Microbiol

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Latex particle agglutination (LPA) testing for antigen to group B streptococcus (GBS) has been useful in the diagnosis of GBS sepsis in newborns. However, recent reports have demonstrated that the sensitivity of LPA assays may be as low as 27 to 54%. The purposes of the present study were to directly compare the abilities of four urine antigen assays to detect GBS antigen with clinical urine samples from neonates with GBS bacteremia and to evaluate the effect of the urine concentration on the sensitivities and specificities of these assays. Urine samples were collected serially from neonates with blood cultures positive for GBS or on admission from healthy full-term infants. One milliliter of urine was removed, and the remainder was concentrated to a volume of 1 ml. Unconcentrated samples were serially diluted with normal saline and were assayed to determine the highest dilution which would produce a positive test result. The Wellcogen, Bactigen, and Directigen LPA tests and ICON immunoassay were directly compared by using concentrated and unconcentrated urine specimens and urine specimens with known titers. A total of 94 urine specimens, including 61 concentrated and 75 unconcentrated specimens, from bacteremic infants were available for sensitivity testing, and 220 urine specimens from uninfected infants were available for specificity testing. There were significant differences in sensitivity among the four assays when they were performed on concentrated urine specimens, as follows: Directigen, 98%; Bactigen, 92%; ICON, 89%; Wellcogen, 68%. When the assays were performed on unconcentrated urine specimens, the Directigen (84%) and Bactigen (76%) assays were each significantly more sensitive than the ICON (59%) or Wellcogen (43%) assay. All four assays were significantly more sensitive in detecting GBS antigen in concentrated than in unconcentrated urine. The Directigen assay detected antigen in higher dilutions (geometric mean titer, 1:5) than the ICON (1:3), Bactigen (1:2), or Wellcogen (1:1) assay. The specificity was 99.5% for all four assays when concentrated urine was used and for the Bactigen, Directigen, and ICON assays when unconcentrated urine was used; the Wellcogen assay was 100% specific when unconcentrated urine was used. We conclude that there are significant differences in sensitivity but not specificity among the commercially available assays for the detection of GBS antigenuria when concentrated and unconcentrated urine specimens are tested. These differences in sensitivity may affect the abilities of clinicians to accurately diagnose GBS sepsis before culture results are available.

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“…Se ha visto que es esta técnica es útil como tamizaje por su alta sensibilidad, bajo costo y fácil implementación. Sin embargo, existe un número importante de falsos positivos (20%) debido a la habitual contaminación de la muestra por contacto con piel del tracto urinario y perirectal 45 . Se describe su especial utilidad en aquellos recién nacidos que han recibido tratamiento antibiótico previo a la toma de cultivos o en los hijos de madres que recibieron profilaxis anteparto 46 .…”

Section: Recomendadounclassified

Sepsis neonatal por Streptococcus Grupo B

Doren

Tapia

et al. 2008

Rev. chil. pediatr.

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Detection of group B streptococcal antigen in body fluids by a latex-coupled monoclonal antibody assay

Cited by 25 publications

References 10 publications

Rapid bacterial antigen detection is not clinically useful

Rapid bacterial antigen detection is not clinically useful

Sensitivity and specificity of rapid diagnostic tests for detection of group B streptococcal antigen in bacteremic neonates

Sepsis neonatal por Streptococcus Grupo B

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