What are the symptoms of bacterial meningitis?

Symptoms of Bacterial Meningitis

Bacterial meningitis presents with highly variable symptoms that differ by age, and the classic triad of fever, neck stiffness, and altered mental status is present in only 41-51% of adult cases, making it critical to maintain a high index of suspicion even when typical signs are absent. 1

Age-Specific Symptom Patterns

Neonates (Birth to 28 Days)

Neonatal bacterial meningitis presents with nonspecific symptoms that make clinical diagnosis particularly challenging 1, 2:

• Irritability and poor feeding are common presenting features 2
• Respiratory distress or failure is frequently reported as an initial symptom 1
• Fever is notably absent in the majority of cases, present in only 6-39% of neonates 1, 2
• Pale or marble skin appearance may be observed 2
• Hyper- or hypotonia (abnormal muscle tone) 2
• Seizures occur in 9-34% of cases, more commonly with Group B streptococcal meningitis 1, 2
• Concomitant septic shock may be present in approximately 25% of cases 1

Children Beyond Neonatal Age

The younger the child, the more subtle and atypical the symptoms, with classic meningeal signs becoming more apparent with increasing age 1:

• Fever is the most common symptom, occurring in 92-93% of cases 1, 2
• Headache shows marked age variation: only 2-9% in children under 1 year versus 75% in children over 5 years 1, 2
• Vomiting is reported in 55-67% of cases 1, 2
• Neck stiffness occurs in 40-82% of pediatric cases 1, 2
• Altered mental status is present in 13-56% of cases 1, 2
• Seizures at hospital admission occur in 10-56% of children 1
• Petechial and purpuric rash is highly suggestive of meningococcal disease (61% of meningococcal cases) but can also occur in pneumococcal meningitis (9% of cases) 1, 2

Adults

Adult presentations are more consistent but still highly variable 1:

• Headache is reported in 58-87% of cases 2
• Fever occurs in 77-97% of cases 2
• Neck stiffness is present in 65-83% of cases 2
• Altered mental status is reported in 30-69% of cases 2
• Petechial or purpuric rash is identified in 20-52% of patients and indicates meningococcal infection in over 90% of cases 1, 2
• The classic triad (fever, neck stiffness, altered mental status) is present in only 41-51% of adult patients 1, 2

Critical Diagnostic Limitations

Poor Sensitivity of Classic Signs

Clinical examination alone has poor diagnostic accuracy and cannot rule out bacterial meningitis 1:

• Neck stiffness has a sensitivity of only 51% in children and 31% in adults 2
• Kernig sign has a sensitivity of 53% in children and 11% in adults 2
• Brudzinski sign has a sensitivity of 66% in children and 9% in adults 2

Key Clinical Pitfalls

• Absence of classic symptoms cannot exclude bacterial meningitis 1, 2
• No single clinical sign is present in all patients 1
• Bacterial meningitis can present solely with nonspecific symptoms, particularly in neonates and young children 1
• Immunocompromised patients and the elderly may have blunted presentations 3

Clinical Approach

Given the poor diagnostic accuracy of clinical signs, cerebrospinal fluid examination is essential for diagnosis when bacterial meningitis is suspected, unless contraindications for lumbar puncture are present 1. The diagnosis cannot be ruled out by clinical examination alone, necessitating a low threshold for lumbar puncture, especially in neonates and young children 1.

Up to 95% of patients will have at least two of the following four cardinal symptoms: fever, nuchal rigidity, altered mental status, and headache 4, making this a more practical screening criterion than the classic triad alone.