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Objective To examine the clinical value of polymerase chain reaction (PCR) in rapid diagnosis of bacterial and fungal infection of central nervous system.Methods The cerebrospinal fluid (CSF) samples were collected from 137 patients for DNA extraction.PCR was used to amplify the DNA of pathogenic bacteria and fungi using universal primers.The PCR products were subjected to DNA sequencing analysis for identifying microbial species.The conventional culture of pathogens was carried out simultaneously as control.Results PCR revealed bacterial pathogen in 50 of the 137 CSF samples,fungal pathogen in 6 of the 137 CSF samples.Conventional culture of CSF reported positive bacterial infection in 38 cases,fungal infection in 5 cases.PCR provided diagnostic sensitivity of 40.9％,specificity 100％,positive predictive value 100％,negative predictive value 38.2％.The diagnostic efficiency was 56.7％.In contrast,the conventional culture achieved the results of 31.4％,100％,100％,34.7％,44.4％,respectively.The sensitivity,negative predictive value,and diagnostic efficiency of PCR were significantly better than conventional culture method.The coincidence rate between PCR and conventional culture was 97.7％.Conclusions Universal primer-based PCR is characteristic of short turnaround time,specificity,sensitivity and accuracy,which is very useful for rapid diagnosis of the pathogenic bacteria and fungi in central nervous system infections.
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Objective To investigate the causes on platelet distribution width (PDW)results not shown in the automatic he-matology analyzer and evaluate the accuracy of the platelet results of these samples with the automatic hematology analyzer. Methods The platelet morphology was observed in microscope for the specimen which PDW were not shown in the auto-matic hematology analyzer.And the platelet results counted in microscope were statistically compared with that in the auto-matic hematology analyzer.Results In the 200 specimens which PDW were not shown in automatic hematology analyzer, there were 104 specimens(52%)in which large platelet was found,36 cases(18%)in which platelet aggregation was visible, 28 cases(14%)in which the microcytes or erythrocyte debris could be seen,32 cases(16%)in which the obvious abnormal was not found.The platelet results counted in microscope for the specimens,in which large platelets,platelet aggregation or microcytes were found,were very different with the results counted with the automatic hematology analyzer(P < 0.05).The PDW of the 200 specimens were rechecked in the automatic hematology analyzer.And 64 cases (32%)PDW results were got,of which 55 cases(85.9%)PDW results were beyond the normal range.Conclusion The main causes for the PDW not shown in automatic hematology analyzer includes large platelets,platelets aggregation and microcytes etc.The platelet re-sults in these specimens by automatic hematology analyzer were different with that counted in microscope.Therefore,the platelet of these specimens should be counted in microscope.
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Objective To understand pathogen spectrum of bacterial and fungal infection of central nervous system (CNS),and evaluate the etiological diagnostic value of universal primer polymerase chain reaction (PCR).Methods Data about patients with suspected or confirmed bacterial and fungal infection of CNS from January 2009 to March 2015 were collected,species of pathogens from cerebrospinal fluid (CSF)were analyzed,DNA from patients’CSF were performed PCR amplification and sequencing with universal primers of bacterial 16S rRNA and fungal 28S rRNA, PCR detection results were compared with CSF culture during the same period.Results A total of 400 patients were with confirmed or suspected bacterial or fungal infection of CNS,132 of whom were with positive CSF culture.150 pathogenic isolates were detected,including 48 isolates of gram-positive bacteria,90 gram-negative bacteria,and 12 fungi;the top three isolated bacteria were Acinetobacter baumannii (n =32 ),coagulase negative staphylococcus (n=16)and Klebsiella pneumoniae (n=13);the most common fungus was Cryptococcus neoformans (n=8).CSF from 88 infected patients and 20 non-infected patients were selected for PCR amplification,the sensitive of PCR am-plification assay was higher than the culture method (35.23% [31/88]vs 28.41 %[25/88],χ2 =4.17,P <0.05).
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Objective To evaluate the value of amplification and sequencing of 16S rRNA gene in the identification of clinical rare pathogenic bacteria,and guide the diagnosis and treatment for related clinical infection.Methods 12 bacterial isolates that were difficult,or unable to be identified with conventional laboratory methods,or with special phenotypes were collected. The 16S rRNA gene was amplified by polymerase chain reaction (PCR),then sequenced for identifying bacterial species through BLAST comparison,clinical characteristics of related infection were ana-lyzed.Results 12 clinical isolates were all positive for PCR amplification (about 1500 bp),species were all identi-fied (similarity≥99% ),the identified strains were Listeriamonocytogenes(n= 2),Brucellamelitensis(n= 2),Fu-sobacteriummortiferum(n= 1),Rothiaaeria(n= 1),Nocardiafarcinica(n= 1),Staphylococcussaccharolyticus (n= 1 ),Rhizobiumradiobacter(n= 1 ),Prevotellabivia(n= 1 ),Ralstoniamannitolilytica(n= 1 ),and Atopobium vaginae(n= 1 ). The sensitivity of 16S rRNA gene amplification was high,and the minimum detection limit of Escherichiacoli ATCC 25922 was 1.5×101 CFU/mL. Clinical data of 12 patients revealed that these strains can cause multi-sites and multi-types of infection,after patients received targeted antimicrobial therapy,11 improved, and 1 died.Conclusion Sequencing for 16S rRNA gene can rapidly and accurately identify rare,anaerobic,and difficult cultured bacteria,provide laboratory evidence for etiological diagnosis and treatment of different types of infection.