Drulak M, Raybould T J, Yong J, Hsiung D, Smith H, Winston S
ADI Diagnostics, Inc., Mississauga, Ontario, Canada.
Diagn Microbiol Infect Dis. 1988 Dec;11(4):181-7. doi: 10.1016/0732-8893(88)90001-6.
A microwell enzyme immunoassay (Visuwell) for direct detection of Group A streptococcal antigen from throat swab specimens has been developed. It incorporates urease conjugated antibody as the detector and is easily interpreted by a yellow to purple color change. Throat specimens obtained on rayon-tipped swabs were transported moist in modified Stuarts medium and cultured before being tested in Visuwell (n = 585, prevalence 17.1%, sensitivity 88%, specificity 92.4%, predictive value positive 70.4%, predictive value negative 97.4%, and accuracy 91.6%). In instances of discrepancy between culture and Visuwell, throat swab extracts were tested in a latex agglutination test. In 21 of 37 instances of Visuwell-positive, culture-negative specimens, latex agglutination was positive. Throat specimens obtained using double rayon swabs and transported to the laboratory dry had one swab cultured and the other tested in Visuwell (n = 280, prevalence 20.4%, sensitivity 75.4%, specificity 88.3%, predictive value positive 62.3%, predictive value negative 93.4%, and accuracy 85.7%). When 1+ culture positive specimens were considered negative, a sensitivity of 97.6% was obtained. In 14 of 26 instances of Visuwell-positive, culture-negative specimens, latex agglutination was positive. Cross-reaction with organisms other than Group A Streptococcus found in the oropharynx was negligible in Visuwell. Limit of detection of Group A streptococcal antigen was equivalent for Visuwell and latex agglutination.
已开发出一种用于直接检测咽喉拭子标本中 A 组链球菌抗原的微孔酶免疫测定法（Visuwell）。它采用脲酶偶联抗体作为检测剂，通过黄色至紫色的颜色变化易于解读。用含人造纤维头的拭子采集的咽喉标本在改良的 Stuart 培养基中湿运，并在 Visuwell 检测前进行培养（n = 585，患病率 17.1%，敏感性 88%，特异性 92.4%，阳性预测值 70.4%，阴性预测值 97.4%，准确性 91.6%）。在培养结果与 Visuwell 结果不一致的情况下，咽喉拭子提取物进行乳胶凝集试验检测。在 Visuwell 检测为阳性但培养为阴性的 37 例标本中，有 21 例乳胶凝集试验呈阳性。使用双人造纤维拭子采集并干燥运送至实验室的咽喉标本，一个拭子用于培养，另一个用于 Visuwell 检测（n = 280，患病率 20.4%，敏感性 75.4%，特异性 88.3%，阳性预测值 62.3%，阴性预测值 93.4%，准确性 85.7%）。当将 1+培养阳性标本视为阴性时，敏感性为 97.6%。在 Visuwell 检测为阳性但培养为阴性的 26 例标本中，有 14 例乳胶凝集试验呈阳性。在 Visuwell 中，与口咽部发现的 A 组链球菌以外的微生物的交叉反应可忽略不计。Visuwell 和乳胶凝集试验对 A 组链球菌抗原的检测限相当。
