Medical Microbiology & Diagnosis

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 Introduction: Despite recent advances in Peritoneal Dialysis (PD), peritonitis remains the most common and serious complication. In a significant proportion of patients a pathogen is not cultured. In this study we investigated the use of 16S rDNA PCR to make a bacterial diagnosis.
Methods: We used an optimised DNA extraction and 16S rDNA PCR with DNA sequencing to detect pathogens in Peritoneal Dialysis-Associated Peritonitis (PDAP).
Results: Seventy-one PD fluids from twenty-four patients were analysed. In suspected cases of PDAP, thirteen out of twenty-one patients had a bacterial pathogen cultured and 16S rDNA PCR with DNA sequencing identified one additional pathogen. However 16S rDNA PCR only detected the pathogen in five of the culture-positive fluids. All follow-up samples were culture-negative, but possible pathogens were identified in three samples by the 16S rDNA PCR.In suspected cases of PDAP the sensitivity and specificity of the PCR was calculated as 69% and 63%, respectively. The negative predictive value of the PCR in follow-up fluids was 100%.
Conclusion: The use of 16S rDNA PCR in diagnosis of PDAP needs further study and improved sensitivity before widespread introduction.

Host protection against viruses depends on mounting an effective innate and adaptive immune response. Aside from the production of type I interferon and inflammation activation, a third line of defense against viral infections is the induction of programmed cell death (apoptosis) in infected cells. Recent work has uncovered essential roles for the cytoslic RNA helicases RIG-I and MDA-5 in the induction of apoptosis in diverse cell types. Here we discuss the mechanisms of RLR-induced programmed cell death as a mechanism of antiviral defense.

Background: Despite the availability of several serological markers, Epstein-Barr virus (EBV) status of some patients is not easily resolved.

Objectives: The aim of the present study was to investigate the quantification and the diagnostic utility of EBV DNA detection as an adjunct to serological diagnosis of primary EBV infection.

Study Design: Sera from 118 patients referred for suspected primary EBV infection, were tested for heterophile antibodies (HA), IgM antibodies against viral capsid antigen (VCA IgM) and IgG against nuclear antigen (EBNA IgG). A quantitative real time EBV PCR assay (Light Cycler EBV Quant kit) was simultaneously performed in plasma of these patients.

Results: EBV DNA was detected in 43 of 46 patients (93.5%) with serologically confirmed primary infection. By performing real time RCR in the remaining 72 samples, 24 additional cases were diagnosed: in 20 of them, VCA IgM was positive but not HA; in 4 cases, HA were positive, but not VCA IgM. EBV DNA load was detectable in all samples drawn until day 12 after onset of symptoms; 20 days after onset all samples were negative. Higher viral load levels were detected in younger patients and in male patients.

Conclusions: The use of EBV PCR assay resulted in an increase in definitive diagnosis of primary EBV infection, enhancing overall diagnostic efficacy by 20.3%. Real time PCR is a reliable tool for diagnosis of primary EBV infection early in the course of disease and may especially serve as a useful diagnostic supplement in serologically unclear cases of EBV infection.