Charles Nauciel

Molecular typing of Legionella pneumophila serogroup 1 isolates from patients and the nosocomial environment by arbitrarily primed PCR and pulsed-field gel electrophoresis.

The ubiquity of Legionella pneumophila in aquatic habitats means that epidemiological evaluation is important for the investigation and control of nosocomial outbreaks of legionellosis. Pulsed-field gel electrophoresis (PFGE) of chromosomal DNA following digestion with SfiI is considered to be one of the most discriminative methods for detecting DNA polymorphisms amongst L. pneumophila serogroup 1 (Lp1) isolates. This paper describes an arbitrarily primed PCR (AP-PCR) method with three different primers (20-mers) for detecting DNA polymorphisms of Lp1 isolates. The AP-PCR assay was compared with PFGE analysis. Both experimental methods were found to have good discriminatory power (discrimination index of 98% and 94.3%, respectively) with 27 unrelated isolates from different geographical areas collected between 1987 and 1997. Furthermore, when the AP-PCR was used in the epidemiological investigation of nosocomial cases of infection, convergent results with the three primers allowed an epidemiological link to be established between isolates from patients and their environment. The AP-PCR method, which is rapid and easy to perform, gave results at least as discriminatory as those obtained with the PFGE method and is proposed for use in the molecular typing of Lp1 outbreaks.

JC virus detection in the cerebrospinal fluid of AIDS patients with progressive multifocal leucoencephalopathy and monitoring of the antiviral treatment by a PCR method

Twenty-four cerebrospinal fluid (CSF) samples from 19 AIDS patients with neurological signs were analysed by the polymerase chain reaction (PCR) for the presence of JC virus (JCV). Eleven of the 19 patients tested presented with progressive multifocal leucoencephalopathy (PML). Two specific JCV target sequences were used for the PCR analysis: a sequence specific for the T antigen genes from both BK virus (BKV) and JCV (PCR1) and a sequence specific for the large T antigen gene from JCV (PCR2). The JCV genome was detected in 10 of 11 patients with PML by the PCR1 method and in all 11 patients by the PCR2 method. With samples from the eight patients without PML, one positive result was obtained with the PCR1 method and this sample and another gave positive results with PCR2. Multiple CSF samples were collected from three patients with PML at different times, including after intrathecal cytarabine treatment, and were tested by the PCR2 method for the presence of the JCV genome. The PCR result became negative for two of the three patients during the cytarabine treatment. However, the absence of a PCR signal was not associated with clinical improvement in these patients. The PCR method is useful for the detection of JCV in CSF samples and in the diagnosis of PML. However, the application of PCR for monitoring the effect of treatment remains to be established.