Comparison of the TestPack Strep A enzyme immunoassay system with anaerobically incubated cultures for detection of group A streptococci from oropharyngeal swabs.
To find a rapid and sensitive test for detection of Group A streptococci (GABS), the performance of the TestPack Strep A (TPSA; Abbott) was compared with culture with the use of rayon-tipped throat swabs from symptomatic patients six months to 90 years of age. Each swab was first inoculated to a 5% sheep blood agar plate and then tested for GABS antigen with the use of the TPSA and the manufacturer's instructions. Cultures were incubated anaerobically at 35 degrees C for 36-48 hours unless positive results were obtained after one night. GABS were identified with a fluorescent antibody method or a latex antibody test. From 1,616 throat swabs, 296 (18.3%) of the cultures contained GABS. The sensitivity and specificity of the TPSA were 73.3% and 94.8%, respectively, whereas the predictive values of positive and negative results were 75.9% and 94.1%, respectively. Results varied significantly, however, with different production lots of TPSA. The TPSA does not appear to provide a sensitive alternative to an anaerobic culture for detection of GABS.
Kellogg
J A
JA
Clinical Microbiology Laboratory, York Hospital, Pennsylvania 17405.
Bankert
D A
DA
Levisky
J S
JS
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D008722:Methods; D008875:Middle Aged; D009960:Oropharynx / Q000382:microbiology*; D010612:Pharyngitis / Q000382:microbiology; D011933:Reagent Kits, Diagnostic; D013297:Streptococcus pyogenes / Q000302:isolation & purification*
D011933:Reagent Kits, Diagnostic