Diagnosis of Listeria monocytogenes Meningoencephalitis by Real-Time PCR for the hly Gene

Abstract

Listeria monocytogenes is a bacterial pathogen that can invade the central nervous system (CNS), causing meningoencephalitis and brain abscesses. The diagnosis of CNS listeriosis, based on the isolation of the bacteria in the cerebrospinal fluid (CSF), can be difficult because of previous antibiotic treatment and a low number of bacteria in the CSF. To improve the sensitivity of microbiological diagnosis, we have developed a real-time PCR assay for detecting and quantifying L. monocytogenes DNA in the CSF. The designed primers specifically amplify the L. monocytogenes hly gene, which encodes listeriolysin O, a pore-forming cytolysin. The PCR assay for the hly gene (PCR-hly) provides reproducible quantitative results over a wide dynamic range of concentrations and was highly sensitive while detecting a single gene copy/ml. By assaying a large panel of bacterial species, including species secreting pore-forming cytolysin, we determined the specificity of the PCR-hly, which exclusively detects the L. monocytogenes DNA. We then analyzed 214 CSF samples from patients suspected of having CNS listeriosis. PCR-hly was positive in all cases in which L. monocytogenes was isolated by culture. Positive PCR-hly of the CSF was also obtained for five additional, clinically confirmed cases of CNS listeriosis for which bacterial cultures were negative presumably due to previous treatment with antibiotics. As a complement to classical bacteriological CSF culture, our designed real-time PCR-hly assay proved to be valuable by enhancing the rapidity and the accuracy of the diagnosis of CNS infection by L. monocytogenes. In addition, the quantitative results provided may, in some instances, be useful for the follow-up of patients under treatment.

Clues to diagnosing culture negativeListeriarhombencephalitis

“…Furthermore, the sensitivity of the technique allows identification of copy numbers as low as 1×100 CFU/ml 10. The merits of this method of detection was exemplified in our case where low copies of the Listeria hyl gene were detected in the CSF from the second lumbar puncture after commencement of antibiotics, although the decision to treat empirically was made prior to confirmation of the organism.…”

Predictive value of the APACHE II, SAPS II, SOFA and GCS scoring systems in patients with severe purulent bacterial meningitis

“…Types of non-purulent bacterial meningitis include tuberculous meningitis, neuroborreliosis and encephalitis, which occur in the course of leptospirosis, syphilis, tularaemia, brucellosis, anaplasmosis and ehrlichiosis. A slightly different course of inflammation occurs in the case of Listeria monocytogenes infection, which typically causes purulent bacterial meningitis and rarely leads to encephalitis and/or brain stem encephalitis, often accompanied by rhombencephalitis and brain abscesses [14].…”

Mirtinas Vaiko Listeriozės Atvejis Po Inksto Transplantacijos

“…Moreover, early suspicion and antibacterial therapy significantly increases the chances of good outcomes in the treatment of listeriosis [13,14]. However, the initial diagnosis of this infection might be challenging due to L. monocytogenes rare microbiologic features and inconspicuous symptoms of listeriosis [15,16].…”