Clinical usefulness of multiplex PCR lateral flow in MRSA detection: a novel, rapid genetic testing method.

Methicillin-resistant Staphylococcus aureus (MRSA) with exogenous cassette DNA containing the methicillin-resistant gene mecA (SCCmec) poses a problem as a drug-resistant bacterium responsible for hospital- and community-acquired infections. The frequency of MRSA detection has recently been increasing rapidly in Japan, and SCCmec has also been classified more diversely into types I-V. A rapid test is essential for early diagnosis and treatment of MRSA infections, but detection by conventional methods requires at least two days. The newly developed multiplex PCR lateral flow method allows specific amplification of femA to detect S. aureus, mecA to detect SCCmec, and kdpC to detect SCCmec type II; moreover, PCR products can be evaluated visually in about 3 h. In the present study, we developed a PCR lateral flow method for MRSA using this method and investigated its clinical usefulness in the detection of MRSA. The results showed a diagnostic concordance rate of 91.7% for MRSA and methicillin-susceptible S. aureus between bacteriological examination and PCR lateral flow, and a high level of specificity in PCR lateral flow. In addition, a higher detection rate for S. aureus using the same sample was observed for PCR lateral flow (70.2%) than for bacteriological tests (48.6%). The above results show that PCR lateral flow for MRSA detection has high sensitivity, specificity, and speed, and its clinical application as a method for early diagnosis of MRSA infections appears to be feasible.

Severe chronic active Epstein-Barr virus infection associated with multiple necrotic lesions in the liver.

We report an atypical presentation of a chronic active Epstein-Barr virus (EBV) infection with multiple nodular coagulation necrosis in the liver, that appeared as hypodense areas on a CT scan. The patient, a 26-year-old man, was hospitalized following over 2 years of intermittent fever, weight loss and liver abnormalities after contracting infectious mononucleosis. We diagnosed his illness as a chronic active EBV infection (CAEBV) because of the high antibody titers against EBV and the histological evidence of organ disease with demonstration of EBV mRNA. A liver biopsy revealed EBV-infected T-cell infiltration with hemophagocytosis and marked hepatocytolytic necrosis. The patient developed multiple coagulation necrosis with well-defined borders surrounding T-cell aggregation in the liver 8 months later. He died of respiratory failure due to interstitial pneumonitis. The analysis of EBV-genome termini demonstrated a clonal proliferation of T-cells harboring EBV, but no T-cell antigen receptor (TCR) gene rearrangement was observed. We speculate that the pathogenesis of this disease was an atypical expression of organ damage as a result of an aberrant T-cell response to EBV infection.