Comparison of a latex agglutination test and four culture methods for identification of group A streptococci in a pediatric office laboratory.
A latex agglutination test and four culture methods for the detection of group A hemolytic streptococci were compared in a pediatric office laboratory. The anaerobic (GasPak) and Detekta-Kit methods produced the highest recovery rates, but aerobic incubation of 5% blood agar plates gave very acceptable results (sensitivity 92%, or 98% if the 1+ positive cultures were eliminated; specificity 100%), and had fewer disadvantages. Delaying inoculation of plates for 2 to 6 hours resulted in significantly greater numbers of strongly positive (3+ and 4+) cultures. The group A selective sheep blood agar media as used in this study offered no advantage. The Culturette test had a sensitivity of 72% and specificity of 98%, compared with the GasPak method, and 77% and 97%, respectively, compared with standard aerobic cultures. Thus it appears too insensitive to be used alone, but might complement culture methods in selected patients.
D000208:Acute Disease; D001431:Bacteriological Techniques; D002648:Child; D003470:Culture Media; D006801:Humans; D007841:Latex Fixation Tests; D010372:Pediatrics; D010612:Pharyngitis / Q000175:diagnosis; D010614:Pharynx / Q000382:microbiology; D011933:Reagent Kits, Diagnostic; D013290:Streptococcal Infections / Q000175:diagnosis; D013297:Streptococcus pyogenes / Q000302:isolation & purification*
D003470:Culture Media; D011933:Reagent Kits, Diagnostic