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Approach to the Critical Patient
Immediate priorities
First-hour bundle
Airway and ventilation risk
GCS 8 or declining
Refractory hypoxemia
Persistent seizures
Hemodynamic instability
MAP < 65 mmHg
Lactate rising despite fluids
Early antimicrobials
Antibiotics within 1 hour when suspected bacterial meningitis
Do not delay antibiotics for CT head or lumbar puncture
Early diagnostics
Blood cultures before antibiotics when feasible without delay
Point-of-care glucose
Infection control
Droplet precautions for suspected meningococcal disease
Precautions until 24 hours after effective antibiotics for meningococcal disease
Neuroprotection and herniation risk
Raised intracranial pressure concern
Rapidly worsening mental status
Escalate to resuscitation bay
Immediate CT head before LP
Focal neurologic deficit
CT head before LP
Papilledema
CT head before LP
New onset seizure
CT head before LP
Immunocompromised state
CT head before LP
Pending LP with high ICP concern
Avoid LP if signs of impending herniation
Critical care and neurology consultation
Sepsis pathway integration
Septic shock pathway
Crystalloid bolus
30 mL/kg within 3 hours for hypotension or lactate 4 mmol/L
Vasopressor strategy
Norepinephrine first-line for persistent hypotension after fluids
Source control
Early antibiotics with CNS penetration
Identify parameningeal source
History
Presentation patterns
Core syndrome features
Fever
Recent antipyretic use
Headache
Sudden onset onset time
Neck stiffness
Pain limiting flexion
Altered mental status
Time course over hours
Photophobia
Light sensitivity
Vomiting
Projectile or persistent
Atypical presentations
Older adults
Confusion without meningismus
Immunocompromised
Blunted fever
Early disease
No neck stiffness
Exposure and risk
Host risk factors
Age over 50 years
Listeria risk
Pregnancy
Listeria risk
Asplenia or complement deficiency
Meningococcal risk
HIV or immunosuppressive therapy
Broad pathogen risk
Alcohol use disorder or chronic liver disease
Pneumococcal risk
Exposure history
Close contact with meningococcal case
Household exposure
Dormitory or military barracks
Meningococcal risk
Recent upper respiratory infection
Pneumococcal risk
Otitis media or sinusitis
Parameningeal source
Head trauma or CSF leak
Pneumococcal or gram negative risk
Neurosurgery or CSF shunt
Healthcare-associated pathogens
Timing and pre-treatment pitfalls
Symptom onset time
Hours since first fever
Higher risk of rapid deterioration
Antibiotics before presentation
Partial treatment
CSF culture yield reduced
Steroid exposure
CSF findings altered
Rash evolution
Rapidly progressive purpura
Meningococcemia concern
Physical Exam
General and vital signs
Physiologic instability
Hypotension
Shock physiology
Tachycardia
Sepsis physiology
Fever or hypothermia
Sepsis marker
Hypoxemia
Respiratory failure risk
Sepsis markers
Mottling
Poor perfusion
Prolonged capillary refill
Poor perfusion
Neurologic exam
Mental status
Confusion
Encephalopathy severity
Lethargy or coma
ICU criteria
Meningeal signs
Nuchal rigidity
Limited passive flexion
Kernig sign
Hamstring resistance
Brudzinski sign
Hip flexion with neck flexion
Focal deficits
Cranial nerve palsy
Basilar meningitis concern
Hemiparesis
Stroke or abscess mimic
Seizure activity
Ongoing convulsions
Status epilepticus pathway
Skin and ENT
Rash
Petechiae
Meningococcemia concern
Purpura
Purpura fulminans concern
ENT source
Otitis media
Pneumococcal risk
Sinus tenderness
Parameningeal source
CSF leak signs
Rhinorrhea or otorrhea
Basilar skull fracture concern
PITFALLS
Early normal neck exam does not exclude meningitis
Meningismus may be absent
Normal temperature does not exclude meningitis
Immunocompromised and elderly
Differential Diagnosis
Life-threatening alternatives
Subarachnoid hemorrhage
Sudden thunderclap headache
ICD-10 I60
Encephalitis
Prominent altered mental status
Temporal lobe features
ICD-10 G04
Brain abscess
Focal deficit
Ring enhancing lesion risk
ICD-10 G06.0
Cerebral venous sinus thrombosis
Headache with focal deficits
Pregnancy or OCP risk
ICD-10 I67.6
Acute bacterial endocarditis with CNS emboli
New murmur
Petechiae
ICD-10 I33
Meningitis mimics and related syndromes
Viral meningitis
Lymphocytic CSF predominance
ICD-10 A87
Tuberculous meningitis
Subacute time course
Basilar signs
ICD-10 A17.0
Fungal meningitis
Immunocompromised host
ICD-10 B45.1
Drug-induced aseptic meningitis
NSAIDs or IVIG exposure
Severe migraine or status migrainosus
Headache without fever
Primary diagnosis coding
Acute bacterial meningitis
ICD-10 G00.9
SNOMED CT 95883001
Pneumococcal meningitis
ICD-10 G00.1
Meningococcal meningitis
ICD-10 A39.0
Listeria meningitis
ICD-10 A32.1
Laboratory Tests
Blood tests
Initial lab bundle
Blood cultures
Two sets before antibiotics when feasible without delay
WHO good practice statement for early blood cultures in suspected acute meningitis
Complete blood count
Leukocytosis or leukopenia for sepsis severity
Electrolytes and creatinine
Renal dosing for antimicrobials
Liver enzymes and bilirubin
Organ dysfunction assessment
Coagulation studies
Platelets and INR before LP if bleeding risk
Venous lactate
Sepsis severity marker
Serum glucose
CSF glucose interpretation
Targeted blood tests
HIV testing when status unknown
Expanded pathogen risk
Procalcitonin
Supportive evidence for bacterial infection
CSF laboratory studies
Core CSF studies
Cell count with differential
Neutrophilic predominance typical for bacterial meningitis
Protein
Elevated protein typical for bacterial meningitis
Glucose with paired serum glucose
CSF glucose low relative to serum
Gram stain
Rapid pathogen clue
Culture
Gold standard for pathogen and susceptibility
Additional CSF studies when indicated
CSF PCR meningitis panel
Adjunct to culture
CSF lactate
Supportive marker for bacterial meningitis
CSF opening pressure
Raised ICP marker
Laboratory interpretation pearls
Typical bacterial CSF profile
WBC often > 1000 per microliter
Neutrophil predominance
Protein often > 1 g/L
Blood brain barrier disruption
Glucose often < 2.2 mmol/L
CSF to serum glucose ratio < 0.4
Partial treatment caveat
Prior antibiotics
Gram stain and culture sensitivity reduced
Diagnostic Tests
Lumbar puncture and CSF acquisition
LP decision pathway
Immediate LP candidates
No focal deficit
No papilledema
No new onset seizure
No severe immunocompromise
CT before LP candidates
Altered mental status
Immunocompromised state
Focal neurologic deficit
New onset seizure
Papilledema
Antibiotics before LP
If CT required and LP delayed
If hemodynamic instability
Blood cultures before antibiotics
Obtain when feasible without delay
Scoring Systems
Pediatric bacterial meningitis score
Use case
Risk stratification in children with CSF pleocytosis
Common components
Positive CSF Gram stain
CSF absolute neutrophil count elevation
CSF protein elevation
Peripheral blood neutrophil count elevation
Seizure at or before presentation
Limitation
Not a substitute for clinical judgment in toxic appearing child
Severity and disposition tools
Glasgow Coma Scale
Low score associated with poor outcome
qSOFA
Sepsis risk screening
MRI
MRI brain utility
Complication assessment
Cerebritis
Abscess
Ventriculitis
Vascular complications
Vasculitis
Venous sinus thrombosis
Limitation
Delay to definitive treatment
CT
CT head role
Pre-LP safety screening in high-risk patients
Altered mental status
Focal neurologic deficit
New onset seizure
Severe immunocompromise
Alternative diagnosis identification
Mass lesion
Hydrocephalus
Hemorrhage
Operational risk
CT before LP associated with antibiotic delays in practice
Ultrasound
Point-of-care ultrasound in shock
RUSH style assessment
Cardiac function
IVC volume status
Lung B lines or effusion
Procedural ultrasound
Vascular access support
Neonatal cranial ultrasound
Hydrocephalus screening in infants with open fontanelle
Disposition
Level of care
ICU admission criteria
Hemodynamic instability
Vasopressor requirement
Respiratory failure
Mechanical ventilation requirement
GCS 12 or rapidly declining
Airway protection risk
Recurrent seizures
Status epilepticus risk
Signs of raised intracranial pressure
Herniation risk
Inpatient admission criteria
Suspected bacterial meningitis
Admission by default
Positive blood culture with CNS symptoms
Treat as meningitis until excluded
Transfer and consultation
Consultation triggers
Infectious diseases
Complex host factors or resistant pathogens
Neurology
Seizures or focal deficits
Neurosurgery
Obstructive hydrocephalus
Shunt infection
Interfacility transfer triggers
ICU requirement without local capacity
Early transfer before decompensation
Public health and prophylaxis logistics
Suspected meningococcal disease
Immediate public health notification
Contact tracing facilitation
Chemoprophylaxis planning for close contacts
Household contacts
Direct exposure to oral secretions
Treatment
Empiric antimicrobial therapy
Time-critical antibiotics
Immediate empiric therapy when suspected
Do not wait for LP results
Blood cultures first when feasible without delay
WHO good practice statement
Community-acquired adult regimens
Age 18 to 50 years
Vancomycin
15 to 20 mg/kg IV every 8 to 12 hours
Trough target 15 to 20 mg/L for CNS infection
Ceftriaxone
2 g IV every 12 hours
Alternative cefotaxime 2 g IV every 4 to 6 hours
Age over 50 years
Vancomycin
15 to 20 mg/kg IV every 8 to 12 hours
Trough target 15 to 20 mg/L
Ceftriaxone
2 g IV every 12 hours
Ampicillin
2 g IV every 4 hours
Listeria coverage
Severe penicillin anaphylaxis
Vancomycin
15 to 20 mg/kg IV every 8 to 12 hours
Moxifloxacin
400 mg IV daily
Trimethoprim sulfamethoxazole
TMP 10 to 20 mg/kg/day IV divided every 6 to 12 hours
Listeria alternative
Healthcare-associated or post-neurosurgery regimens
Vancomycin
15 to 20 mg/kg IV every 8 to 12 hours
Trough target 15 to 20 mg/L
Antipseudomonal beta lactam
Cefepime
2 g IV every 8 hours
Ceftazidime
2 g IV every 8 hours
Meropenem
2 g IV every 8 hours
Pediatric regimens
Age over 1 month
Ceftriaxone
50 mg/kg IV every 12 hours
Maximum 2 g per dose
Vancomycin
15 mg/kg IV every 6 hours
Trough target 15 to 20 mg/L for CNS infection
Neonate
Ampicillin
50 mg/kg IV every 6 hours
Adjust by gestational and postnatal age
Cefotaxime
50 mg/kg IV every 6 to 8 hours
Avoid ceftriaxone in neonates when possible
Targeted therapy after identification
Narrowing strategy
Culture and susceptibility guided de-escalation
Stop vancomycin when pneumococcus susceptible to beta lactam
Duration by pathogen
Neisseria meningitidis 7 days
Haemophilus influenzae 7 days
Streptococcus pneumoniae 10 to 14 days
Listeria monocytogenes 21 days or longer
Gram negative bacilli 21 days or longer
Adjunctive corticosteroids
Dexamethasone strategy
Adult suspected or proven pneumococcal meningitis
Dexamethasone 0.15 mg/kg IV every 6 hours
Maximum 10 mg per dose
Start 15 to 20 minutes before or with first antibiotic dose
Continue 2 to 4 days per local protocol
Continuation decision
Continue if pneumococcal meningitis confirmed or strongly suspected
Stop if alternative pathogen identified where no benefit expected
Antiviral and other coverage when uncertain
Encephalitis overlap concern
Acyclovir
10 mg/kg IV every 8 hours
Renal adjustment required
Add when prominent altered mental status or focal temporal features
Supportive and complication management
Seizure management
Benzodiazepine first-line
Lorazepam 0.1 mg/kg IV
Maximum 4 mg per dose
Second-line antiseizure medication
Levetiracetam 60 mg/kg IV
Maximum 4500 mg
Fever and pain control
Acetaminophen
15 mg/kg PO or PR every 6 hours
Maximum 1000 mg per dose
Raised intracranial pressure management
Head of bed elevation
30 degrees
Hyperosmolar therapy for herniation physiology
Hypertonic saline 3 percent
2 mL/kg IV bolus
Repeat based on neurologic response
Mannitol
0.5 to 1 g/kg IV bolus
Avoid in hypotension
Shock management
Norepinephrine infusion
Initiate 0.05 microgram/kg/min
Titrate every 2 to 5 minutes to MAP 65 mmHg
Special Populations
Pregnancy
Pregnancy considerations
Listeria coverage
Ampicillin inclusion in empiric therapy when suspected
Maternal sepsis risk
Early obstetrics consultation
Fetal monitoring
Viability based approach
Geriatric
Older adult considerations
Atypical presentation
Delirium predominant
Listeria risk
Ampicillin inclusion age over 50 years
Renal dosing
Vancomycin monitoring
Pediatrics
Pediatric considerations
Age-stratified pathogens
Neonate gram negative and group B strep
Infant and child pneumococcus and meningococcus
Dexamethasone uncertainty
Routine use controversial in many pediatric protocols
Weight-based dosing
Use actual weight
Maximum adult doses where applicable
Background
Epidemiology
Epidemiology basics
Medical emergency with high morbidity and mortality
Early antibiotics improve outcomes
Common adult pathogens
Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocytogenes in older adults and immunocompromised
Pediatric epidemiology in Canada
Empiric therapy rationale includes third-generation cephalosporin plus vancomycin
Pathophysiology
Pathophysiology core
Bloodstream invasion
Hematogenous spread to meninges
Blood brain barrier disruption
CSF protein elevation
Inflammatory cascade
Cerebral edema
Raised intracranial pressure
Vascular complications
Vasculitis and infarction
Therapeutic Considerations
Antibiotic principles
High-dose bactericidal therapy
CNS penetration required
Early treatment priority
Do not delay for imaging or LP when unstable
Steroid rationale
Inflammation reduction
Mortality and neurologic sequelae benefit in pneumococcal meningitis in adults
Diagnostic timing principle
LP as soon as safe
Etiology definition and de-escalation enablement
Patient Discharge Instructions
copy discharge instructions
Discharge context
Typical bacterial meningitis requires admission
Discharge instructions apply after inpatient treatment completion or after bacterial meningitis excluded
Follow-up plan
Primary care follow-up within 7 days
Audiology follow-up when pneumococcal or Hib meningitis
Return immediately for
Worsening headache
New severe pain
Fever recurrence
Temperature 38.0 C or higher
Confusion or excessive sleepiness
New behavior change
Seizure
Any convulsion
New weakness or speech trouble
Focal neurologic symptoms
New rash
Purple spots or bruising
Persistent vomiting
Inability to keep fluids down
Household contact precautions
Meningococcal exposure concern
Public health instructions for chemoprophylaxis
References
Guidelines and evidence sources
Core guidelines and summaries
IDSA practice guideline for bacterial meningitis
Practice Guidelines for the Management of Bacterial Meningitis
Canadian Paediatric Society position statement on suspected bacterial meningitis management
Empiric third-generation cephalosporin plus vancomycin rationale
WHO overview of meningitis guidelines
Blood cultures as soon as possible preferably before antibiotics
CT before LP evidence and summaries
Cleveland Clinic Journal of Medicine review on imaging before LP
Imaging before LP for focal deficit immunodeficiency altered mental status seizure
Adult CT before LP indications observational data
Abnormal consciousness immunocompromise focal deficit new onset seizures common triggers
Adjunctive dexamethasone references
Emergency Care BC meningitis management summary
Dexamethasone 0.15 mg/kg IV every 6 hours and timing with antibiotics
Pediatric dexamethasone protocol examples
0.15 mg/kg dose with maximum 10 mg per dose
Dosing references
Merck Manual antibiotic dosing table for acute bacterial meningitis
Ceftriaxone and cefotaxime adult and pediatric doses
ACEP evidence framework reference
ACEP clinical policies methodology and evidence grading context
ACEP clinical policies resource page
Source file
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.