Bokermann Sérgio, Zanella Rosemeire C, Lemos Ana Paula S, de Andrade Ana Lúcia S S, Brandileone Maria Cristina de C
Bacteriology Branch, Adolfo Lutz Institute, Secretary of Health of the State of São Paulo, São Paulo, Brazil.
J Clin Microbiol. 2003 Dec;41(12):5546-50. doi: 10.1128/JCM.41.12.5546-5550.2003.
To assess the magnitude of discrepant results obtained by routine Haemophilus influenzae serotyping, 258 isolates, collected by the epidemiological surveillance system in Brazil from individuals with invasive diseases or carriage, were evaluated by two slide agglutination (SlAg) methods: SlAg method 1, by which strains were initially screened with a serotype b-specific antiserum, and SlAg method 2, by which strains were tested against all serotype-specific antisera in parallel. Investigators comparing results of the two SlAg methods with those obtained by capsule type-specific PCR were blinded to the method used. The serotype prevalence rates found by the three methods were significantly different, involving discrepancies mainly between serotype b and noncapsulated (NC) isolates. For invasive isolates (n = 131), the overall agreement rate between SlAg method 1 or 2 and PCR was 68.0 or 88.3%, respectively, whereas for colonizing isolates (n = 127) the corresponding rate was 46.5 or 94.2%, respectively. SlAg method 2 improved the ascertainment of serotypes over that obtained with SlAg method 1, demonstrating good correlation with PCR. Use of the polyvalent antiserum as a screening reagent for SlAg for invasive and colonizing isolates showed poor discriminatory power, with a sensitivity of 65.8% and a specificity of 91.7%. We stress the importance of using a well-standardized SlAg methodology and suggest that reference laboratories should utilize PCR routinely to confirm SlAg results and to check all nonspecific SlAg reactions and apparent NC isolates by SlAg in order to provide reliable data on the prevalence of H. influenzae serotypes in the H. influenzae type b vaccine era.
为评估常规流感嗜血杆菌血清分型所获结果的差异程度，巴西流行病学监测系统从患有侵袭性疾病或携带该病菌的个体中收集了258株分离株，采用两种玻片凝集（SlAg）方法进行评估：SlAg方法1，先用b型特异性抗血清对菌株进行初步筛选；SlAg方法2，同时用所有血清型特异性抗血清对菌株进行检测。比较两种SlAg方法与通过荚膜型特异性PCR所获结果的研究人员，对所使用的方法并不知情。三种方法所发现的血清型流行率存在显著差异，主要差异存在于b型血清型和无荚膜（NC）分离株之间。对于侵袭性分离株（n = 131），SlAg方法1或2与PCR之间的总体一致率分别为68.0%或88.3%，而对于定植分离株（n = 127），相应的一致率分别为46.5%或94.2%。与SlAg方法1相比，SlAg方法2提高了血清型的确定率，与PCR显示出良好的相关性。将多价抗血清用作侵袭性和定植分离株SlAg的筛选试剂，其鉴别能力较差，灵敏度为65.8%，特异性为91.7%。我们强调使用标准化良好的SlAg方法的重要性，并建议参考实验室应常规使用PCR来确认SlAg结果，并通过SlAg检查所有非特异性SlAg反应和明显的NC分离株，以便提供关于b型流感嗜血杆菌疫苗时代流感嗜血杆菌血清型流行率的可靠数据。
