J Clin Pathol Qual Control.  1998 Jun;20(1):225-229.

Evaluation of Spot CAMP Test for Rapid Identification of Group B Streptococci

• Uh Y
• Jang IH
• Yoon KJ

Abstract

BACKGROUND: The standard CAMP test is commonly used by clinical laboratories because of its higher sensitivity and specificity when compared with other presumptive identification tests of group B streptococci (GBS), and their relative simplicity and cost effectiveness compared with serologic identification. One drawback, however, is that standard CAMP test requires at least 18 hours of incubation. To evaluate the clinical usefulness of the spot CAMP test, we compared a 30-minute spot CAMP test with the standard overnight CAMP test.
METHODS
The standard CAMP test and the spot CAMP test were performed for 150 GBS isolates from clinical specimens during the period of March 1990 to February 1998. The standard CAMP test was prepared by growing Staphylococcus aureus (ATCC 25923) in Todd-Hewitt broth for 48 hours at 35degrees C. The broth culture was centrifuged, and the supernatant was filtered through a 0.45 micrometer syringe filter. One drop of beta-lysin filtrates were dispensed by using a 1.0 mL syringe. Plates were held at room temperature for 30 minutes. An arc or circle of enhanced hemolysis next to the colony where the reagent was dropped was considered a positive reaction.
RESULTS
The spot CAMP test was positive on 147 isolates including seven nonhemolytic strains among the 150 clinical isolates of GBS. The spot CAMP test demonstrated 99.3% correlation with a standard CAMP test.
CONCLUSION
The spot CAMP test was easy to perform and accurate, and could presumptively identify colonies of GBS growing on primary isolation plates within 30 minutes.

MeSH Terms

Cost-Benefit Analysis
Hemolysis
Sensitivity and Specificity
Staphylococcus aureus
Syringes