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目的了解天津市应用聚合酶链反应(PCR)方法对百日咳病例的诊断效果,探讨确诊病例分子流行病学特点。方法选取天津市医院及社区监测的百日咳疑似病例110例,采集鼻咽拭子标本,应用PCR法检测百日咳杆菌的筛选及验证基因;同时采用酶联免疫吸附试验(ELISA)法检测血清中特异性百日咳毒素IgG(PT-IgG)抗体;采用PCR扩增确诊病例百日咳毒素(PT)S1亚单位基因,进行序列测定和分析。结果 110例百日咳疑似病例中,PCR检测阳性率60.00%;ELISA检测94例,PT-IgG抗体阳性率42.55%,2种方法检测阳性率差异有统计学意义(χ2=6.181,P=0.013);<1岁病例PCR检测阳性率高于其他年龄段;19株百日咳杆菌基因测序的亲缘性关系密切,核苷酸同源性为99.88%;在PT区域S1亚单位第218位氨基酸发生变异,蛋氨酸(Met)变异为异亮氨酸(Iso)。结论天津市百日咳杆菌基因的亲缘性关系密切;应用PCR检测鼻咽拭子进行百日咳病例确诊,方法敏感,操作易行。
Objective To understand the diagnostic value of polymerase chain reaction (PCR) in the case of pertussis in Tianjin and to explore the molecular epidemiological characteristics of confirmed cases. Methods Totally 110 suspected cases of pertussis were collected from hospitals and communities in Tianjin. Nasopharyngeal swab specimens were collected. The screening and validation of Bordetella pertussis were detected by PCR. The specificity of serum was determined by enzyme linked immunosorbent assay (ELISA) Pertussis toxin IgG (PT-IgG) antibody was amplified by PCR. The pertussis toxin (PT) S1 subunit gene was confirmed by PCR and sequenced and analyzed. Results The positive rate of PCR detection in 110 cases of pertussis was 60.00%. The positive rate of PT-IgG antibody was 42.55% in 94 cases detected by ELISA, the positive rate of the two methods was statistically significant (χ2 = 6.181, P = 0.013). The positive rate of PCR detection in cases of <1 year old was higher than that of other age groups. The sequence of 19 B. pertussis genes was closely related to the nucleotide sequence. The nucleotide homology was 99.88%. In the PT region, the 218th amino acid in the S1 subunit was mutated, (Met) to isoleucine (Iso). Conclusion The genetic relationship of B. pertussis genes in Tianjin is closely related. The detection of nasopharyngeal swabs by PCR for the diagnosis of whooping cough cases is sensitive and easy to operate.