Dataset Information

Rapid diagnosis of bacterial meningitis by real-time PCR and fluorescence in situ hybridization.

ABSTRACT: Real-time PCR and fluorescence in situ hybridization (FISH) were evaluated as rapid methods for the diagnosis of bacterial meningitis and compared to standard diagnostic procedures. For PCR, a LightCycler approach was chosen, implementing eubacterial and specific PCR assays for the most relevant bacteria. For FISH, a similar probe set containing eubacterial and specific probes was composed of published and newly designed probes. Both methods were evaluated by use of cerebrospinal fluid (CSF) samples from patients with suspected bacterial meningitis. For all microscopy- and culture-positive samples (n = 28), the eubacterial PCR was positive. In addition, all identifiable pathogens were detected with specific PCR assays, according to an algorithm based on the Gram stain. The FISH method detected the pathogen in 13 of 18 positive samples. While the FISH method remained negative for all microscopy- and culture-negative samples (n = 113), the eubacterial PCR was positive for five of these samples. Sequencing of the amplicon revealed the presence of Neisseria meningitidis, Streptococcus agalactiae, and Haemophilus influenzae in three of these five samples. In addition, samples with discordant results by culture and microscopy were successfully investigated by PCR (10 samples) and FISH (5 samples). In conclusion, PCR is a highly sensitive tool for rapid diagnosis of bacterial meningitis. FISH is less sensitive but is useful for the identification of CSF samples showing bacteria in the Gram stain. Based on our results, an approach for laboratory diagnosis of meningitis including PCR and FISH is discussed.

SUBMITTER: Poppert S

PROVIDER: S-EPMC1169125 | biostudies-literature | 2005 Jul

REPOSITORIES: biostudies-literature

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Rapid diagnosis of bacterial meningitis by real-time PCR and fluorescence in situ hybridization.

Poppert Sven S Essig Andreas A Stoehr Barbara B Steingruber Adelinde A Wirths Beate B Juretschko Stefan S Reischl Udo U Wellinghausen Nele N

Journal of clinical microbiology 20050701 7

Real-time PCR and fluorescence in situ hybridization (FISH) were evaluated as rapid methods for the diagnosis of bacterial meningitis and compared to standard diagnostic procedures. For PCR, a LightCycler approach was chosen, implementing eubacterial and specific PCR assays for the most relevant bacteria. For FISH, a similar probe set containing eubacterial and specific probes was composed of published and newly designed probes. Both methods were evaluated by use of cerebrospinal fluid (CSF) sam ...[more]

PMID: 16000464

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Project description:BackgroundToxoplasmosis is an infectious disease caused by the parasitic protozoan Toxoplasma gondii. It is endemic worldwide and, depending on the geographic location, 15 to 85% of the human population are asymptomatically infected. Routine diagnosis is based on serology. The parasite has emerged as a major opportunistic pathogen for immunocompromised patients, in whom it can cause life-threatening disease. Moreover, when a pregnant woman develops a primary Toxoplasma gondii infection, the parasite may be transmitted to the fetus and cause serious damage. For these two subpopulations, a rapid and accurate diagnosis is required to initiate treatment. Serological diagnosis of active infection is unreliable because reactivation is not always accompanied by changes in antibody levels, and the presence of IgM does not necessarily indicate recent infection. Application of quantitative PCR has evolved as a sensitive, specific, and rapid method for the detection of Toxoplasma gondii DNA in amniotic fluid, blood, tissue samples, and cerebrospinal fluid.MethodsTwo separate, real-time fluorescence PCR assays were designed and evaluated with clinical samples. The first, targeting the 35-fold repeated B1 gene, and a second, targeting a newly described multicopy genomic fragment of Toxoplasma gondii. Amplicons of different intragenic copies were analyzed for sequence heterogeneity.ResultsComparative LightCycler experiments were conducted with a dilution series of Toxoplasma gondii genomic DNA, 5 reference strains, and 51 Toxoplasma gondii-positive amniotic fluid samples revealing a 10 to 100-fold higher sensitivity for the PCR assay targeting the newly described 529-bp repeat element of Toxoplasma gondii.ConclusionWe have developed a quantitative LightCycler PCR protocol which offer rapid cycling with real-time, sequence-specific detection of amplicons. Results of quantitative PCR demonstrate that the 529-bp repeat element is repeated more than 300-fold in the genome of Toxoplasma gondii. Since individual intragenic copies of the target are conserved on sequence level, the high copy number leads to an ultimate level of analytical sensitivity in routine practice. This newly described 529-bp repeat element should be preferred to less repeated or more divergent target sequences in order to improve the sensitivity of PCR tests for the diagnosis of toxoplasmosis.

Dataset Information

Rapid diagnosis of bacterial meningitis by real-time PCR and fluorescence in situ hybridization.

Publications

Rapid diagnosis of bacterial meningitis by real-time PCR and fluorescence in situ hybridization.

Similar Datasets

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