WHO Recommends PCR Testing in 'First Ever' Global Meningitis Guidelines

Original from: 360dx

The World Health Organization on Thursday issued the first global guidelines for meningitis diagnosis, treatment, and care.

Considered by WHO to be a major global public health challenge, meningitis can be caused by bacteria, viruses, fungi, and parasites infecting the membranes surrounding the brain and spinal cord. For bacterial meningitis, specifically, infection proves to be fatal in one out of six cases, while approximately 20 percent of people have severe complications from infection.

"Implementing these new guidelines will help save lives, improve long-term care for those affected by meningitis, and strengthen health systems," said Tedros Adhanom Ghebreyesus, WHO director-general, in a statement.

The new guidelines strongly recommend performance of a Gram stain on cerebrospinal fluid samples, as well as determination of total and differential white blood cell count, protein concentration, glucose concentration, and the cerebrospinal fluid-to-blood glucose ratio. They also conditionally recommend CSF lactate level assessment in cases where antibiotic therapy has not yet been administered. 

While CSF culture is considered the gold standard to determine antimicrobial susceptibility, WHO also strongly recommended CSF be assayed using PCR-based molecular tests for relevant pathogens in individuals with suspected acute meningitis.

The latter guideline was supported by an extensive meta-analysis of CSF molecular testing. 

In the guidelines, WHO said individual PCR testing "is highly sensitive and specific across the most common bacterial pathogens, including S. pneumoniae, N. meningitidis, and H. influenzae type b, while the diagnostic performance is lower for enteroviruses." 

Meanwhile, multiplex PCR testing demonstrates "an overall high diagnostic yield, but sensitivity and specificity may vary substantially based on the causative pathogen and setting," the WHO guidelines said, noting the potential for false positives and false negatives. 

The guidelines also highlighted that both singleplex and multiplex PCR should be considered, and the choice should be made based on available technical and infrastructural resources. 

WHO guided that PCR results be interpreted in conjunction with concurrent clinical presentation and laboratory findings, given the varying diagnostic performance of PCR. 

The WHO also said that CSF culture and AST should not be replaced by PCR and should be routinely performed as the gold standard tests for pathogen identification and characterization of antibiotic resistance profiles. "Where resources permit, blood cultures along with AST should also be performed in individuals with suspected acute meningitis," WHO said.

The new guidelines provide recommendations for clinical management of children over 1 month of age, adolescents, and adults with acute, community-acquired bacterial or viral meningitis. The recommendations are applicable worldwide, directed at healthcare professionals and policymakers, and were specifically developed to guide implementation in low- and middle-income countries, WHO said.

Prior WHO guidelines on meningitis were issued in 2014 and only applied in epidemic meningitis contexts.

Epidemics of meningitis are seen across the world, particularly in sub-Saharan Africa, and prior recommendations issued in 2014 applied to epidemic contexts. At that time, WHO strongly recommended verification PCR or culture before a decision to initiate a vaccine response in cases where rapid diagnostic tests — either latex agglutination or immunochromatography dipsticks — were used to investigate an outbreak and were positive for a vaccine preventable serogroup. Four RDTs were assessed in 2014, including latex agglutination tests from Pastorex and Becton Dickinson, and immunochromatographic tests from Abbott and the Centre for Medical Research and Health in Niamey (CERMES), Niger.

Source: WHO Recommends PCR Testing in 'First Ever' Global Meningitis Guidelines