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目的评价荚膜多糖基因(capsular polysaccharide synthesis locus,CPS)聚合酶链反应(polymerase chain reaction,PCR)在肺炎链球菌病例临床诊断中的应用价值。方法收集保定市各医院诊断为肺炎病例的临床标本,其中痰液1850份、血液1 850份、脑脊液245份,分别进行cps A基因PCR检测和传统细菌培养,比较两种方法对肺炎链球菌的检测结果。同时根据cps基因血清特异性区域设计引物,采用多重聚合酶链反应(multiplex polymerase chain reaction,MP-PCR)对210株肺炎链球菌分型,并与荚膜肿胀试验结果进行比较分析。结果 cps A基因PCR检测法在3945份临床标本中检出肺炎链球菌600例,检出率为15.21%,高于细菌培养法。以细菌培养法为参考标准,cps A基因PCR检测肺炎链球菌的灵敏度为97.67%,特异度为89.54%。且在两种方法中痰液中肺炎链球菌检出率均高于血液与脑脊液,差异具有统计学意义(P<0.05)。210株肺炎链球菌中,198株被MP-PCR法分出血清型,分型率为94.29%,高于荚膜肿胀试验。两种方法鉴定血清型别一致率达80.81%。其中有7株被荚膜肿胀试验鉴定为其它型别:63株多重PCR鉴定为19F的菌株中,有5株被荚膜肿胀试验鉴定为6A;35株多重PCR鉴定为19A菌株中,有1株被荚膜肿胀试验鉴定为19F;8株多重PCR鉴定为14的菌株中,有1株被荚膜肿胀试验鉴定为19A。结论 cpsA基因PCR检测和cps基因血清特异性区域的MP-PCR检测在肺炎链球菌检出和分型上优于传统细菌培养法和荚膜肿胀试验,可用于肺炎链球菌的临床诊断,且标本以痰液为宜。
Objective To evaluate the clinical value of polymerase chain reaction (PCR) of capsular polysaccharide synthesis locus (CPS) in the diagnosis of Streptococcus pneumoniae. Methods The clinical samples of pneumonia were collected from hospitals in Baoding. Among them, 1850 sputum, 1 850 blood and 245 cerebrospinal fluid were collected for PCR detection of cps A gene and traditional bacterial culture respectively. Test results. At the same time, 210 strains of S. pneumoniae were typed by multiplex polymerase chain reaction (MP-PCR) based on the serum-specific region of cps gene and compared with capsular swelling test results. Results The cps A gene PCR test detected 3945 clinical specimens of S. pneumoniae in 600 cases, the detection rate was 15.21%, higher than the bacterial culture. Bacterial culture method as a reference standard, cps A gene PCR detection of S. pneumoniae sensitivity of 97.67%, a specificity of 89.54%. And in both methods, the detection rate of S. pneumoniae in sputum was higher than that in blood and cerebrospinal fluid, the difference was statistically significant (P <0.05). Of the 210 Streptococcus pneumoniae isolates, 198 were serotyped by MP-PCR, with a typing rate of 94.29%, which was higher than that of capsular swelling test. The two methods identified serotypes consistent rate of 80.81%. Seven of them were identified as other types by capsular swelling test. Of 63 strains identified as 19F by multiplex PCR, 5 strains were identified as 6A by capsular swelling test and 35 strains were identified as 19A by multiplex PCR Strains were identified by capsular swelling test as 19F; of the 8 strains identified by multiplex PCR, 14 were identified as 19A by capsular swelling test. Conclusion PCR detection of cpsA gene and MP-PCR detection of cps gene serum-specific region are superior to traditional bacterial culture and capsular swelling test in the detection and typing of S. pneumoniae, which can be used for clinical diagnosis of S. pneumoniae. Sputum is appropriate.