Ambiguity in the Identification of Streptococcus pneumoniae Optochin, Bile Solubility, Quellung, and the AccuProbe DNA Probe Tests

摘要: We prospectively evaluated 639 sequential clinical isolates of alpha-hemolytic gram-positive cocci as possible Streptococcus pneumoniae. On the basis results tests for optochin susceptibility, tube bile solubility, and quellung reaction, 74 strains (11.6%) were categorized unequivocal pneumococci (optochin positive, solubility reaction positive). Among 450 optochin- solubility-negative organisms, a subset 56 was tested (all negative); these nonpneumococci. A final 115 organisms with an inconsistent or discordant combination susceptibility to optochin, equivocal strains. With isolates, commercial molecular probe S pneumoniae (AccuProbe; Gen-Probe, San Diego, Calif) showed 100% sensitivity (74/74) specificity (56/56). strains, however, 33 (28.7%) reacted AccuProbe, whereas only 3 (2.6%) capsule that in test. identified this group primarily respiratory may have been partially expressed their classic phenotype rarely capsular antigens. practical, cost-sparing algorithm is proposed facilitate routine identification