Coagulation, coma, and outcome in bacterial meningitis--an observational study of 38 adult cases

Human Listeriosis

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that can cause severe invasive infections upon ingestion with contaminated food. Clinically, listerial disease, or listeriosis, most often presents as bacteremia, meningitis or meningoencephalitis, and pregnancy-associated infections manifesting as miscarriage or neonatal sepsis. Invasive listeriosis is life-threatening and a main cause of foodborne illness leading to hospital admissions in Western countries. Sources of contamination can be identified through international surveillance systems for foodborne bacteria and strains' genetic data sharing. Large-scale whole genome studies have increased our knowledge on the diversity and evolution of L. monocytogenes, while recent pathophysiological investigations have improved our mechanistic understanding of listeriosis. In this article, we present an overview of human listeriosis with particular focus on relevant features of the causative bacterium, epidemiology, risk groups, pathogenesis, clinical manifestations, and treatment and prevention.

D-Dimer Combined With CRP Can Improve the Differential Value of Bacterial Meningitis and Tuberculous Meningitis

OBJECTIVE

To explore the diagnostic value of the coagulation marker D-dimer and its combination with the traditional marker C-reactive protein (CRP) in distinguishing bacterial meningitis (BM) from tuberculous meningitis (TM).

METHODS

We performed a retrospective study on specimens from 173 patients with meningitis who were hospitalized at the First Affiliated Hospital of Guangxi Medical University, Guangxi, China, from 2012 through 2020. The patient records were divided into the BM group and the TM group, and hematological parameters D-dimer and CRP were evaluated for the 2 groups.

RESULTS

The levels of D-dimer and CRP in the BM group were significantly higher than those levels in the TM group (P ˂.001 for each), and the sensitivity and specificity of the combined detection of the 2 markers was 86.3% to 100%; the area under the receiver operating characteristic (ROC) curve reached 0.983 (95% confidence interval [CI], 0.966-0.999).

CONCLUSION

D-dimer testing has high specificity in distinguishing between BM and TM; CRP testing also has high sensitivity. The combined diagnosis of the 2 biomarkers helps to distinguish TM from BM.

COVID-19 - Toward a comprehensive understanding of the disease

The evidence on the pathophysiology of the novel coronavirus SARS-CoV-2 infection is rapidly growing. Understanding why some patients suffering from COVID-19 are getting so sick, while others are not, has become an informal imperative for researchers and clinicians around the globe. The answer to this question would allow rationalizing the fear surrounding this pandemic. Understanding of the pathophysiology of COVID-19 relies on an understanding of interplaying mechanisms, including SARS-CoV-2 virulence, human immune response, and complex inflammatory reactions with coagulation playing a major role. An interplay with bacterial co-infections, as well as the vascular system and microcirculation affected throughout the body should also be examined. More importantly, a compre-hensive understanding of pathological mechanisms of COVID-19 will increase the efficacy of therapy and decrease mortality. Herewith, presented is the current state of knowledge on COVID-19: beginning from the virus, its transmission, and mechanisms of entry into the human body, through the pathological effects on the cellular level, up to immunological reaction, systemic and organ presentation. Last but not least, currently available and possible future therapeutic and diagnostic options are briefly commented on.

Characterization of a Listeria monocytogenes meningitis mouse model

BACKGROUND

Listeria monocytogenes is a common cause of bacterial meningitis. We developed an animal model of listerial meningitis.

METHODS

In survival studies, C57BL/6 mice received intracisternal injections with different L. monocytogenes sequence type 1 (ST1) colony forming units per milliliter (CFU; n = 48, 105, 106, 107, 108, and 109 CFU/ml). Second, mice were inoculated with 108 CFU/ml ST1 and sacrificed at 6 h and 24 h (n = 12/group). Outcome parameters were clinical score, CFUs, cyto- and chemokine levels, and brain histopathology. Third, 84 mice were inoculated (109 CFU/ml ST1) to determine optimal antibiotic treatment with different doses of amoxicillin and gentamicin. Fourth, mice were inoculated with 109 CFU/ml ST1, treated with amoxicillin, and sacrificed at 16 h and 24 h (n = 12/group) for outcome assessment. Finally, time point experiments were repeated with ST6 (n = 24/group).

RESULTS

Median survival time for inoculation with 108 and 109 CFU/ml ST1 was 46 h and 40 h; lower doses of bacteria led to minimal clinical signs of disease. Brain levels of IL-6, IL-17A, and IFN-γ were elevated at 24 h, and IL-1β, IL-6, IL-10, IFN-γ, and TNF-α were elevated in blood at 6 h and 24 h. Histopathology showed increased meningeal infiltration, vascular inflammation of meningeal vessels, hemorrhages, and ventriculitis. In the treatment model, brain levels of IL-6 and IL-17A and blood levels of IL-6 and IFN-γ were elevated. Compared to ST6, infection with ST1 led initially to higher levels of IL-1β and TNF-α in blood and more profound neuropathological damage. At 16 h post inoculation, IL-1β, IL-10, and TNF-α in blood and IL-6, IL17A, TNF-α, and IFN-γ levels in brain were higher in ST1 compared to ST6 without differences in CFUs between STs. At 24 h, neuropathology score was higher in ST1 compared to ST6 (p = 0.002) infected mice.

CONCLUSIONS

We developed and validated a murine model of listerial meningitis. ST1-infected mice had a more severe inflammatory response and brain damage as compared to ST6-infected mice.

Antithrombotic therapy for secondary stroke prevention in bacterial meningitis in children

OBJECTIVE

To assess the safety and efficacy of antithrombotic therapy (ATT) for secondary stroke prevention of childhood bacterial meningitis.

STUDY DESIGN

A retrospective study of cases of stroke associated with bacterial meningitis in 2 pediatric hospitals during a period of 15 years. Patients were included in the study if they were between 28 days and 18 years of age and had at least 2 serial neuroimaging studies during the acute phase of their illness. The safety of ATT was assessed by the presence or absence of intracranial hemorrhage. Efficacy was assessed by the failure in preventing stroke recurrence. Neurologic outcome was determined by the last documented Pediatric Stroke Outcome Measure score.

RESULTS

Twenty-two cases of childhood bacterial meningitis complicated by stroke were identified. Six cases were treated with heparin after either initial or recurrent infarction. None of the cases receiving heparin had further recurrence. Aspirin (acetylsalicylic acid [ASA]) was started after the initial or after recurrent infarction in 10 cases. Four (40%) had infarctions on ASA; 3 of these patients subsequently received heparin. In the 14 cases in which no ATT was begun, 8 (57%) had further recurrence of infarction. None of the patients, whether receiving heparin or ASA, had intracranial hemorrhage.

CONCLUSION

In this small sample, heparin and ASA appeared to be safe in childhood bacterial meningitis complicated by stroke and may be effective in improving outcome. Heparin may be more effective than aspirin in preventing recurrent infarction.

Intracerebral hemorrhages in adults with community associated bacterial meningitis in adults: should we reconsider anticoagulant therapy?

Objective

To study the incidence, clinical presentation and outcome of intracranial hemorrhagic complications in adult patients with community associated bacterial meningitis.

Methods

Nationwide prospective cohort study from all hospitals in the Netherlands, from 1 March 2006, through 31 December 2010.

Results

Of the 860 episodes of bacterial meningitis that were included, 24 were diagnosed with intracranial hemorrhagic complications: 8 upon presentation and 16 during clinical course. Clinical presentation between patients with or without intracranial hemorrhage was similar. Causative bacteria were Streptococcus pneumoniae in 16 patients (67%), Staphylococcus aureus in 5 (21%), Pseudomonas aeruginosa and Listeria monocytogenes both in 1 patient (4%). Occurrence of intracranial hemorrhage was associated with death (63% vs. 15%, P<0.001) and unfavorable outcome (94% vs. 34%, P<0.001). The use of anticoagulants on admission was associated with a higher incidence of intracranial hemorrhages (odds ratio 5.84, 95% confidence interval 2.17–15.76).

Conclusion

Intracranial hemorrhage is a rare but devastating complication in patients with community-associated bacterial meningitis. Since anticoagulant therapy use is associated with increased risk for intracranial hemorrhage, physicians may consider reversing or temporarily discontinuing anticoagulation in patients with bacterial meningitis.

Pathogenesis and pathophysiology of pneumococcal meningitis

Pneumococcal meningitis continues to be associated with high rates of mortality and long-term neurological sequelae. The most common route of infection starts by nasopharyngeal colonization by Streptococcus pneumoniae, which must avoid mucosal entrapment and evade the host immune system after local activation. During invasive disease, pneumococcal epithelial adhesion is followed by bloodstream invasion and activation of the complement and coagulation systems. The release of inflammatory mediators facilitates pneumococcal crossing of the blood-brain barrier into the brain, where the bacteria multiply freely and trigger activation of circulating antigen-presenting cells and resident microglial cells. The resulting massive inflammation leads to further neutrophil recruitment and inflammation, resulting in the well-known features of bacterial meningitis, including cerebrospinal fluid pleocytosis, cochlear damage, cerebral edema, hydrocephalus, and cerebrovascular complications. Experimental animal models continue to further our understanding of the pathophysiology of pneumococcal meningitis and provide the platform for the development of new adjuvant treatments and antimicrobial therapy. This review discusses the most recent views on the pathophysiology of pneumococcal meningitis, as well as potential targets for (adjunctive) therapy.