# Diagnosis of Healthcare-Associated Ventriculitis and Meningitis -- IDSA 2017

## Scope

This guideline addresses **healthcare-associated** (nosocomial) ventriculitis and meningitis occurring after neurosurgical procedures, placement of CSF shunts or drains, head trauma, or other healthcare exposures. It does not cover community-acquired bacterial meningitis.

## Clinical Presentation

### CSF Shunt Infections

- New headache, nausea, lethargy, and/or change in mental status suggest CSF shunt infection (Strong, Moderate).
- Erythema and tenderness over the subcutaneous shunt tubing indicate infection of the shunt hardware (Strong, Moderate).
- Fever without an identifiable source may suggest CSF shunt infection but is nonspecific (Weak, Low).
- Abdominal tenderness, peritonitis, or pseudocyst formation in patients with ventriculoperitoneal (VP) shunts suggest shunt infection (Strong, Moderate).
- Bacteremia in patients with ventriculoatrial (VA) shunts suggests shunt-related bloodstream infection (Strong, Moderate).

### Post-Neurosurgical and Post-Traumatic Infections

- New headache, fever, evidence of meningeal irritation, seizures, and/or worsening mental status in post-neurosurgical or post-traumatic patients suggest healthcare-associated meningitis or ventriculitis (Strong, Moderate).
- Wound infection or dehiscence at the neurosurgical site should raise suspicion for underlying meningitis (Strong, Moderate).

## CSF Analysis and Culture

### CSF Culture

- CSF cultures remain the **most important diagnostic test** to establish the diagnosis of healthcare-associated ventriculitis and meningitis (Strong, High).
- If initial CSF culture results are negative in patients with CSF shunts or drains with suspected infection, cultures should be held for **at least 10 days** to identify slow-growing organisms such as *Propionibacterium acnes* (now *Cutibacterium acnes*) (Strong, High).
- When a CSF shunt or drain is removed for suspected infection, components of the device should be sent for culture (Strong, Moderate).
- In patients with ventriculoatrial (VA) shunts, blood cultures should be obtained in addition to CSF cultures (Strong, High).

### Limitations of CSF Cell Count, Glucose, and Protein

- **Abnormalities of CSF cell count, glucose, and/or protein may not be reliable indicators** of healthcare-associated ventriculitis and meningitis (Weak, Moderate).
  - CSF pleocytosis may result from recent neurosurgery, intraventricular hemorrhage, intrathecal chemotherapy, or other non-infectious causes.
  - A normal CSF profile does not exclude infection, particularly with low-virulence organisms such as coagulase-negative staphylococci or *P. acnes*.

### Gram Stain

- A negative Gram stain does **not** exclude infection (Strong, Moderate).
- Gram stain sensitivity is limited, particularly for low-virulence or low-burden infections.

### Diagnostic Classification

The guideline distinguishes three categories for positive CSF cultures:

| Category | CSF Culture | CSF Chemistry | Clinical Symptoms |
|---|---|---|---|
| **Contamination** | Single positive culture | Normal cell count, glucose, protein | Absent |
| **Colonization** | Multiple positive cultures | Normal cell count, glucose, protein | Absent |
| **Infection** | Positive cultures | Pleocytosis and/or hypoglycorrhachia | Present (headache, fever, altered mental status, meningeal signs) |

- **Infection** is diagnosed when positive CSF cultures occur in the setting of CSF pleocytosis and/or hypoglycorrhachia **AND** compatible clinical symptoms.
- Repeat CSF sampling is recommended to distinguish contamination from true infection when clinical suspicion is low (Strong, Moderate).

## Adjunctive Diagnostic Tests

### CSF Lactate and Procalcitonin

- Elevated CSF lactate (>4 mmol/L) or CSF procalcitonin may aid in the diagnosis of healthcare-associated ventriculitis and meningitis (Weak, Moderate).
- Elevated serum procalcitonin may help differentiate infection from post-surgical or post-hemorrhagic CSF changes (Weak, Low).

### Molecular Diagnostics

- PCR and nucleic acid amplification testing may increase pathogen identification, particularly when cultures are negative due to prior antibiotic exposure (Weak, Low).

### Fungal Biomarkers

- CSF beta-D-glucan and galactomannan testing may be useful in the diagnosis of fungal ventriculitis and meningitis (Strong, Moderate).

## Neuroimaging

- **MRI with gadolinium enhancement and diffusion-weighted imaging** is recommended for the evaluation of suspected healthcare-associated ventriculitis and meningitis (Strong, Moderate).
  - Findings suggestive of ventriculitis include ependymal enhancement, periventricular signal changes, and restricted diffusion in the ventricular system.
- **Ultrasound or CT of the abdomen** should be performed in patients with VP shunts presenting with abdominal symptoms (e.g., peritonitis, pseudocyst) (Strong, Moderate).

> **OpenMedicine Calculator:** `calculate_gcs` -- available via MCP for automated scoring to assess level of consciousness in patients with suspected CNS infection.

## Limitations

- CSF cell count, glucose, and protein are frequently abnormal in post-neurosurgical patients even without infection, reducing their diagnostic specificity.
- Most recommendations are based on observational studies and expert opinion (low to moderate quality evidence).
- The diagnostic classification (contamination vs. colonization vs. infection) relies on clinical judgment in conjunction with laboratory findings and does not have validated scoring criteria.
- *P. acnes* infections may present with indolent courses and minimal CSF abnormalities, making diagnosis challenging even with extended culture incubation.
