Comparison of commercially available group B streptococcal latex agglutination assays

Ascher, David P.; Wilson, Samuel; Fischer, Gerald W.

doi:10.1128/jcm.29.12.2895-2896.1991

Cited by 7 publications

(2 citation statements)

References 9 publications

(10 reference statements)

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“…With either concentrated or unconcentrated urine, the Wellcogen assay detected antigen in significantly fewer urine samples than the other assays did. This result is consistent with the findings of the previous in vitro study (1). Although the manufacturer of the ICON assay does not specifically recommend concentration of the urine, we found that this immunoassay was significantly less sensitive than the Bactigen and Directigen assays when we tested unconcentrated urine.…”

Section: Discussionsupporting

confidence: 92%

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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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Section: Discussionsupporting

confidence: 92%

“…Scheffé post hoc F test for multiple comparisons, P Ͻ 0.05. (1). However, clinical specimens from infants with invasive GBS disease were not used in their study.…”

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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Medically Important Beta-Hemolytic Streptococci

Cleary¹,

Cheng²

2006

The Prokaryotes

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Evaluation of a rapid agglutination test for detection of group B streptococci in the gastric aspirates of neonates

Poîlane

Adam

Torlotin

et al. 1995

Eur. J. Clin. Microbiol. Infect. Dis.

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A rapid commercial agglutination test (Bactigen Strepto B) for detection of group B streptococci in gastric aspirates of neonates was evaluated. One hundred and sixty-one gastric samples were analyzed with conventional bacteriological techniques and with the commercial test after modification of the extraction technique. The sensitivity of the test relative to the culture technique was 90.4%, the specificity 94.2%, the positive predictive value 70.3% and the negative predictive value 98.5%. The commercial test could be performed in one hour and showed good sensitivity and specificity. If a test result was negative colonization could be excluded, obviating the need for empirical antibiotic therapy, whereas a positive result suggested colonization or neonatal infection with group B streptococci.

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Comparison of commercially available group B streptococcal latex agglutination assays

Cited by 7 publications

References 9 publications

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

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

Medically Important Beta-Hemolytic Streptococci

Evaluation of a rapid agglutination test for detection of group B streptococci in the gastric aspirates of neonates

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