Adult pneumococcal meningitis presenting with normocellular cerebrospinal fluid: two case reports

First reported case of hydrocephalus in jointly diagnosed bacterial meningitis and a colloid cyst: how Ockham's razor became Hickam's dictum

We report the first case in the literature of acute hydrocephalus due to a simultaneous diagnosis of bacterial (not asceptic) meningitis and a colloid cyst. Diagnosing disease is the cornerstone skill of a medical practitioner. Both education and experience allow for sharpening of this skill throughout years of medical practice. Disease is fraught with nuances and inconsistencies which can render an accurate diagnosis a difficult task. Medical practitioners can be guilty of cognitive biases such as Ockham's razor. We present the case of a patient with an initial diagnosis of obstructive hydrocephalus secondary to a colloid cyst. However, pneumococcal meningitis blunted Ockham's razor in favour of Hickam's dictum.

Microbiological Outcomes Associated With Low Leukocyte Counts in Cerebrospinal Fluid

The significance of low leukocyte counts in cerebrospinal fluid (CSF) remains unclear. We performed a 2-year retrospective study to examine microbiological outcomes associated with CSF leukocytes at 6–10/mm³. Of the 178 samples examined, we detected positive results for 11 samples, including 5 cases of tick-borne encephalitis virus infection.

A systematic review of cases of meningitis in the absence of cerebrospinal fluid pleocytosis on lumbar puncture

Background

Definitive diagnosis of meningitis is made by analysis of cerebrospinal fluid (CSF) culture or polymerase chain reaction (PCR) obtained from a lumbar puncture (LP), which may take days. A timelier diagnostic clue of meningitis is pleocytosis on CSF analysis. However, meningitis may occur in the absence of pleocytosis on CSF.

Areas of Uncertainty: A diagnosis of meningitis seems less likely without pleocytosis on CSF, leading clinicians to prematurely exclude this. Further, there is little available literature on the subject.

Methods

Ovid/Medline and Google Scholar search was conducted for cases of CSF culture-confirmed meningitis with lack of pleocytosis. Inclusion criterion was reported cases of CSF culture-positive or PCR positive meningitis in the absence of pleocytosis on LP. Exclusion criteria were pleocytosis on CSF, cases in which CSF cultures/PCR were not performed, and articles that did not include CSF laboratory values.

Results

A total of 124 cases from 51 articles were included. Causative organisms were primarily bacterial (99 cases). Outcome was reported in 86 cases, 27 of which died and 59 survived. Mortality in viral, fungal and bacterial organisms was 0, 56 and 31%, respectively. The overall percentage of positive initial CSF PCR/culture for viral, fungal and bacterial organisms was 100, 89 and 82%, respectively. Blood cultures were performed in 79 of the 124 cases, 56 (71%) of which ultimately cultured the causative organism. In addition to bacteremia, concomitant sources of infection occurred in 17 cases.

Conclusions

Meningitis in the absence of pleocytosis on CSF is rare. If this occurs, causative organism is likely bacterial. We recommend ordering blood cultures as an adjunct, and, if clinically relevant, concomitant sources of infection should be sought. If meningitis is suspected, empiric antibiotics/antifungals should be administered regardless of initial WBC count on lumbar puncture.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4204-z) contains supplementary material, which is available to authorized users.

Does This Adult Patient With Jolt Accentuation of Headache Have Acute Meningitis?

OBJECTIVE

In order to identify appropriate candidates with suspected meningitis for lumbar puncture (LP), study designs and diagnostic values of jolt accentuation of headache (JA) were reviewed.

BACKGROUND

Acute meningitis is a life-threatening disease that requires LP for accurate diagnosis. JA was reported the most sensitive indicator of cerebrospinal fluid pleocytosis; however, subsequent studies have failed to confirm this claim.

METHODS

We reviewed articles concerning JA, published prior to December 2017, using MEDLINE and Japanese medical databases. Seven original articles based on independent cohorts were eligible for inclusion and articles citing these 7 were thoroughly searched (11 in total). Additionally, all medical records of our previously reported cohort were reviewed again to explore how the patients' background influenced diagnostic values of JA.

RESULTS

We hypothesized that an oversimplified dichotomy of JA findings, pleocytosis, and meningitis created a misconception that JA is a universal indicator of meningitis. We clarify the difference between them and present altered mental status (AMS) as a key to decrease the sensitivity of JA. Notably, the sensitivity and specificity of JA were relatively low in unselected groups, while they tended to be high in the selected sub-groups with acute onset of headache and fever, without AMS or neurological deficits. Unselected populations included etiologies of pleocytosis other than acute meningitis, which might weaken the association between JA and pleocytosis.

CONCLUSION

JA is not a universal, stand-alone, indicator of meningitis in febrile patients with headache. Therefore, we propose a stepwise approach for patients with suspected acute meningitis. AMS or neurological deficits suggest an intracranial pathology, which may necessitate a lumbar puncture. JA seems a useful tool for distinguishing acute aseptic meningitis from upper respiratory infection when used in the selected cohort of febrile patients (≥37°C) with recent-onset headache (within 2 weeks before presentation) and normal mental status. This approach and diagnostic values of JA should be further investigated by prospective studies using operationally sorted candidates.

Bacterial meningitis in the absence of cerebrospinal fluid pleocytosis: A case report and review of the literature

Bacterial meningitis is typically diagnosed with a lumbar puncture, which usually reveals an elevated opening pressure and high white blood cell count. In this article, the authors report a case involving an 83-year-old woman who had normal cerebrospinal fluid findings on presentation, but who was subsequently found to have meningitis caused by Neisseria meningitidis. The authors discuss potential reasons for normal cerebrospinal fluid findings in the context of meningitis.

Elevation of cerebrospinal fluid (CSF) cell count is a key sign in the diagnosis of bacterial meningitis. However, there have been reports of bacterial meningitis with no abnormalities in initial CSF testing. This type of presentation is extremely rare in adult patients. Here, a case involving an 83-year-old woman who was later diagnosed with bacterial meningitis caused by Neisseria meningitidis is described, in whom CSF at initial and second lumbar puncture did not show elevation of cell counts. Twenty-six non-neutropenic adult cases of bacterial meningitis in the absence of CSF pleocytosis were reviewed. The frequent causative organisms were Streptococcus pneumoniae and N meningitidis. Nineteen cases had bacteremia and seven died. The authors conclude that normal CSF at lumbar puncture at an early stage cannot rule out bacterial meningitis. Therefore, repeat CSF analysis should be considered, and antimicrobial therapy must be started immediately if there are any signs of sepsis or meningitis.