Lankinen K S, Salo P, Rapola S, Salo E, Takala A K, Leinonen M
Department of Bacterial Respiratory Infections, National Public Health Institute, Helsinki, Finland.
Am J Trop Med Hyg. 1997 Feb;56(2):211-5. doi: 10.4269/ajtmh.1997.56.211.
Bacterial culture of Streptococcus pneumoniae followed by serotyping is not always feasible under field conditions. Antigen detection methods could be an alternative, but they are associated with sensitivity problems. In an effort to improve their sensitivity, we introduced an enrichment phase before antigen detection and compared the results with direct bacterial culture, using nasopharyngeal swabs from 95 children with symptoms of acute respiratory infection. Antigen detection was performed by latex agglutination and counterimmunoelectrophoresis. Streptococcus pneumoniae was found in 29 (30%) of the samples by culture, and in 42 (44%) by antigen detection after enrichment, an excess of 45% over culture findings. This excess was shown to represent true positive samples since pneumococcal DNA could be detected by polymerase chain reaction in all 15 antigen-positive, culture-negative samples. Two culture-positive samples were antigen-negative; in one of these the bacteria were nonencapsulated. We conclude that for type-specific demonstration of S. pneumoniae, detection of pneumococcal antigen after an enrichment step is a sensitive method that can be applied for epidemiologic study purposes, e.g., in vaccine trials, in areas without ready access to a good microbiology laboratory.
在现场条件下，对肺炎链球菌进行细菌培养并随后进行血清分型并不总是可行的。抗原检测方法可能是一种替代方法，但它们存在灵敏度问题。为了提高其灵敏度，我们在抗原检测前引入了一个富集阶段，并将结果与直接细菌培养进行比较，使用了95名有急性呼吸道感染症状儿童的鼻咽拭子。通过乳胶凝集和对流免疫电泳进行抗原检测。通过培养在29份（30%）样本中发现了肺炎链球菌，在富集后通过抗原检测在42份（44%）样本中发现了肺炎链球菌，比培养结果多出45%。由于在所有15份抗原阳性、培养阴性的样本中都能通过聚合酶链反应检测到肺炎球菌DNA，所以这种多出的情况被证明代表真正的阳性样本。有两份培养阳性的样本抗原阴性；其中一份样本中的细菌是无荚膜的。我们得出结论，对于肺炎链球菌的型特异性检测，在富集步骤后检测肺炎球菌抗原是一种灵敏的方法，可用于流行病学研究目的，例如在疫苗试验中，在无法方便地使用良好微生物实验室的地区。
