Retrospective analysis of multiplex polymerase chain reaction-based molecular diagnostics (SES) in 70 patients with suspected central nervous system infections: A single-center study

Distinguishing community-acquired bacterial and viral meningitis: Microbes and biomarkers

Diagnostic tools to differentiate between community-acquired bacterial and viral meningitis are essential to target the potentially lifesaving antibiotic treatment to those at greatest risk and concurrently spare patients with viral meningitis from the disadvantages of antibiotics. In addition, excluding bacterial meningitis and thus decreasing antibiotic consumption would be important to help reduce antimicrobial resistance and healthcare expenses. The available diagnostic laboratory tests for differentiating bacterial and viral meningitis can be divided microbiological pathogen-focussed methods and biomarkers of the host response. Bacterial culture-independent microbiological methods, such as highly multiplexed nucleic acid amplification tests, are rapidly making their way into the clinical practice. At the same time, more conventional host protein biomarkers, such as procalcitonin and C-reactive protein, are supplemented by newer proteomic and transcriptomic signatures. This review aims to summarise the current state and the recent advances in diagnostic methods to differentiate bacterial from viral meningitis.

Evaluation of Multiplex Real-time PCR and WHO Criteria for Diagnosing Childhood Bacterial Meningitis in a Tertiary Referral Hospital in Iran

Background: Childhood bacterial meningitis (BM) requires prompt and precise diagnosis to provide proper treatment and decline mortality and morbidity. Objectives: We aimed to evaluate the World Health Organization (WHO) criteria and polymerase chain reaction (PCR) for diagnosing BM in children admitted to a tertiary referral hospital in Shiraz, southern Iran. Materials: We included all 492 children aged one month to 17 years suspected of meningitis who had cerebrospinal fluid (CSF) leukocytosis admitted to Nemazi Hospital from August 2016 to September 2017. The CSF specimens were examined for routine analysis, Gram staining, and culture. A multiplex real-time PCR was used to identify Streptococcus pneumoniae, Haemophilus influenzae type b (Hib), and Neisseria meningitidis in the CSF samples. Seven viruses were also investigated using real-time PCR. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using the WHO criteria and the multiplex real-time PCR results. Results: Seventy-four CSF samples had leukocytosis. Nineteen (22.9%) patients had BM caused by S. pneumoniae (n = 14), Hib (n = 2), Salmonella enterica (n = 2), and N. meningitidis (n = 1). The PCR test detected all cases, except for two with Salmonella meningitis (sensitivity 89.4%, specificity 100%, PPV 100%, and NPV 96%). The WHO criteria detected all cases, except three who received antibiotics at least four days before performing lumbar puncture (sensitivity 84.2%, specificity 98.2%, PPV 94.1%, and NPV 94.7%). Enterovirus was the most common viral etiology (6.75%). Conclusions: The WHO criteria and the multiplex real-time PCR had high accuracy in our setting, and their use could decrease the antibiotic over-prescription in febrile children suspected of meningitis.

Diagnostic challenges of central nervous system infection: extensive multiplex panels versus stepwise guided approach

BACKGROUND

Cerebrospinal fluid (CSF) testing is a key component for the diagnosis of central nervous system (CNS) infections. Current meningitis and encephalitis management guidelines agree on the need for CSF molecular testing in combination with other direct and indirect biological testing, both in CSF and blood. Multiplex molecular tests have been developed to reduce turnaround times and facilitate the diagnostic approach.

OBJECTIVES

We aim to discuss the role of multiplex molecular panels in the management of CNS infections.

SOURCES

The MEDLINE database and the grey literature have been searched for relevant articles.

CONTENT

New molecular multiplex panels are being developed to simultaneously detect a large array of neuropathogens in CSF. Although one of these assays has been US Food and Drug Administration-approved, extensive analytical and clinical validation is still missing, and suboptimal performance related issues have been raised. Its use has been associated with decreased costs, reduced length of hospital stay and reduced antiviral therapy administration in retrospective, industry-sponsored studies. The pros and cons of this multiplex syndromic approach are discussed in this narrative review.

IMPLICATIONS

Molecular multiplex CNS infection diagnosis panels have been developed and present several attractive features, including ease of use and low turnaround time. However, suboptimal analytical performances render these tests difficult to use without additional confirmatory tests. Such panels are not comprehensive nor adapted to all situations, depending on the epidemiological or clinical context. Overall, available data in the literature currently do not support the use of a multiplex PCR panel in clinical routine as a 'stand-alone' molecular assay. Except in restricted laboratory capacity settings where such easy-to-use multiplex panels offer the diagnostic means that would otherwise not be available, the stepwise testing approach remains a more rational option. Serological testing both in blood and CSF should not be neglected, but it represents essential complementary tools regarding some neuropathogens.

Syndrome Evaluation System for Simultaneous Detection of Pathogens Causing Acute Encephalitic Syndrome in India, Part-2: Validation Using Well Characterized Clinical Samples

Diagnosis of the aetiological agent in case of acute encephalitic syndrome (AES) continues to pose a challenge in clinical practice as a variety of pathogens are known to cause AES. Here, we report the validation of a Syndrome Evaluation System (SES) developed for simultaneous detection of multiple AES pathogens using a well characterized set of Cerebrospinal fluid (CSF) samples. The validation of the SES was carried out in two phases. In the first phase, the SES was validated using 51 CSF samples obtained from autopsy proven cases and 50 samples obtained from apparently healthy individuals undergoing spinal anesthesia for minor surgeries served as "controls." The SES detected etilogical agent in 48/51 (94.11 %) samples obtained from autopsy proven AES cases while all the 50 CSF samples obtained from "controls" were negative. In the second phase, the SES was validated using well characterized CSF samples obtained from AES patients fulfilling the WHO case definition of AES (Group I; n = 207) and samples that were collected from patients with non-infectious neurological disorder (Group II; n = 90). All the samples were tested using multiple conventional/serological assays and categorized into various groups. Amongst the AES cases fulfilling WHO case definition, the SES detected AES pathogens in 160/207 (77.29%) cases while conventional serological/molecular assays were able to detect AES pathogens only in 77/207 (37.1%) of cases. Further, in 12/83 CSF samples that were positive by SES and negative by conventional serological/molecular tests, the results were additionally confirmed by sequencing the PCR products to rule out non-specific amplification in the SES. In patients with non-infectious neurological disorders the SES detected latent viruses 12/90 CSF samples. These results indicate that the SES, apart being a rapid, sensitive, specific, and cost-effective method provides the major advantage of simultaneous detection of multiple pathogens using as single specimen of CSF.

Progressive multifocal leukoencephalopathy in idiopathic CD4+ lymphocytopenia

Progressive multifocal leukoencephalopathy is a central nervous system demyelinating disease caused by infection with John Cunningham virus. It affects predominantly the subcortical white matter, producing progressive neurological deficits and large confluent white matter lesions on imaging. It is usually seen in immunodeficient individuals, such as those suffering from acquired immunodeficiency syndrome, those on treatment with monoclonal antibodies, and those following therapeutic bone marrow suppression. Here, we report a rare case of progressive multifocal leukoencephalopathy in an apparently immunocompetent adult, who was found to have idiopathic CD4 lymphocytopenia upon further investigation.