What is invasive pneumococcal disease?

Invasive pneumococcal disease (IPD) refers to serious infections in which Streptococcus pneumoniae (the pneumococcus) is isolated from normally sterile body sites — most importantly blood (bacteraemia), cerebrospinal fluid (pneumococcal meningitis) or pleural fluid (empyema). The leading forms: Pneumococcal meningitis — the most common bacterial meningitis in adults in HICs; 20% case fatality; 25-30% permanent disability (deafness, brain damage). Pneumococcal bacteraemia — fever, sepsis syndrome; 10-20% mortality. Pneumococcal empyema — pus in the pleural space; requires drainage. S. pneumoniae also causes non-invasive (blood culture-negative) community-acquired pneumonia and otitis media — the most common cause globally.

What pneumococcal vaccines are available?

Two types: Pneumococcal conjugate vaccines (PCVs): PCV7 (2000, withdrawn); PCV13 (Prevenar 13, Pfizer); PCV15 (Vaxneuvance, Merck); PCV20 (Apexxnar, Pfizer — approved 2021-2022). Conjugate vaccines are T-cell dependent — long-lasting immune response; booster effect; reduces nasopharyngeal carriage (herd effect). Recommended for children (primary infant series) and for adults ≥65 years, and younger adults with risk factors. PPV23 (Pneumovax): 23-valent polysaccharide; for adults — broader coverage but less durable; recommended as complement to PCV20 for immunocompromised/asplenic patients.

What is overwhelming post-splenectomy infection?

Asplenic patients (those who have had the spleen surgically removed, or who have functional asplenia from sickle cell disease, coeliac disease, lupus or other causes) are at lifelong risk of overwhelming post-splenectomy infection (OPSI) — a fulminant septicaemia that progresses from apparent health to death within hours. Most commonly caused by encapsulated bacteria: S. pneumoniae (most common, 50%), N. meningitidis, H. influenzae type b. Every asplenic patient MUST receive: pneumococcal vaccination (PCV20 followed by PPV23); MenACWY and MenB vaccines; Hib vaccine; prophylactic oral penicillin (lifelong or minimum 2 years); medical alert bracelet; supply of empirical antibiotics for self-start in emergency.

How is pneumococcal meningitis treated?

Empirical treatment (before culture/sensitivity): ceftriaxone 2g IV 12-hourly + vancomycin 15-20mg/kg IV 8-hourly (to cover penicillin-resistant S. pneumoniae until susceptibility known) + dexamethasone 0.15mg/kg IV 6-hourly × 4 days (MUST be given before or with first antibiotic dose). Once sensitivity confirmed: if fully sensitive to penicillin → penicillin G; if intermediate → ceftriaxone; if highly resistant → continue ceftriaxone + vancomycin. Duration: minimum 10-14 days for pneumococcal meningitis.

What is serotype replacement and why does it matter?

Vaccine serotypes (those covered by PCV) were eliminated from nasopharyngeal carriage and invasive disease after vaccination campaigns — but non-vaccine serotypes expanded to fill the ecological niche, a phenomenon called serotype replacement. After PCV7, non-PCV7 serotypes (especially 19A and 3) rose dramatically. After PCV13, serotypes 8, 10A, 11A, 12F, 15B, 22F and 33F emerged as the dominant IPD causes. PCV15 and PCV20 were developed specifically to address these replacement serotypes. The evolutionary cat-and-mouse between vaccines and serotype replacement is the defining epidemiological challenge of pneumococcal disease control.

How does GMJ News cover invasive pneumococcal disease?

GMJ News covers WHO/ECDC IPD burden, PCV vaccine evolution (PCV7 to PCV20), serotype replacement dynamics, OPSI in asplenic patients, dexamethasone in meningitis (timing critical), penicillin resistance (PRSP), and pneumococcal vaccination schedule for adults. IPD — the leading adult bacterial meningitis cause — is directly relevant to PHIG's vaccination programme and hospital accreditation infection control standards.

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Invasive Pneumococcal Disease

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Invasive pneumococcal disease (IPD) — bacteraemia, meningitis or other blood-culture-proven infection with Streptococcus pneumoniae — remains the leading cause of community-acquired bacterial meningitis in adults in high-income countries and a major cause of childhood mortality in LMICs, causing approximately 1.6 million deaths per year globally despite the existence of highly effective conjugate vaccines that have dramatically reduced paediatric IPD burden since 2000 (ECDC). Pneumococcal vaccination has expanded from PCV7 (2000) to PCV13 (2010) to PCV15 and PCV20 (approved 2021-2022) for adults — yet serotype replacement by non-vaccine strains, and the extreme vulnerability of asplenic patients to overwhelming post-splenectomy infection (OPSI), mean pneumococcus remains a critical clinical and public health priority.

Key messages

1.6M deaths/year — leading adult bacterial meningitis cause

Streptococcus pneumoniae causes approximately 1.6 million deaths per year globally — predominantly in children under 5 in LMICs and older adults. It is the leading cause of community-acquired bacterial meningitis in adults in HICs and the most common cause of bacterial pneumonia and bacteraemia (ECDC/WHO).

PCV20 — broader protection since 2021

Pneumococcal conjugate vaccines have expanded: PCV7 (2000) → PCV13 (2010) → PCV15 and PCV20 (2021-2022). PCV20 covers 20 serotypes including the increasingly prevalent serotypes 8, 10A, 11A, 12F, 15B, 22F and 33F that emerged as serotype replacement after PCV13.

Serotype replacement — the evolutionary challenge

As vaccine serotypes are eliminated, non-vaccine serotypes expand to fill the ecological niche — serotype replacement has partially offset the vaccine impact. PCV15 and PCV20 were developed specifically to address the most prevalent replacement serotypes (especially 15B, 22F, 8, 10A, 11A, 12F).

OPSI — asplenic patients face extreme risk

Overwhelming post-splenectomy infection (OPSI) — most commonly caused by S. pneumoniae — is a medical emergency with a case fatality rate of 50-70% and can progress from apparently well to death within hours. All asplenic patients MUST receive pneumococcal vaccination (PCV20 + PPV23) and lifelong penicillin prophylaxis.

Dexamethasone — reduces meningitis mortality and deafness

IV dexamethasone given before or with the first antibiotic dose in bacterial meningitis (including pneumococcal) reduces mortality and hearing loss risk. Must NOT be given after antibiotics — the anti-inflammatory benefit requires timing with the first dose.

Penicillin-resistant S. pneumoniae (PRSP) — AMR concern

Penicillin-resistant and multidrug-resistant pneumococcus (PRSP) has spread globally. Empirical meningitis treatment requires ceftriaxone + vancomycin until susceptibility is known. PCV13 coverage of PRSP serotypes (particularly 19A) reduced resistance rates in vaccinated cohorts.

Key statistics

~1.6M

pneumococcal deaths/year globally (WHO)

WHO

PCV20

broadest pneumococcal conjugate vaccine — 20 serotypes (2021-22)

FDA/EMA 2021-22

50-70%

case fatality rate of OPSI in asplenic patients

ECDC/Splenectomy guidelines

cause of community-acquired bacterial meningitis in adults in HICs

WHO/ECDC

25-30%

of pneumococcal meningitis survivors have permanent neurological sequelae

ECDC

Before

dexamethasone must be given BEFORE or WITH first antibiotic dose in meningitis

WHO/IDSA

IPD incidence by age group and vaccine era — ECDC EU/EEA data

Source: ECDC. Children <2 years and adults >65 bear the highest burden; PCV13 dramatically reduced childhood IPD.

Glossary of key terms

Streptococcus pneumoniae (pneumococcus)
WHOA Gram-positive diploccoccus — the most important bacterial respiratory pathogen. 93 serotypes defined by polysaccharide capsule structure. Causes invasive disease (bacteraemia, meningitis, empyema — IPD) and non-invasive disease (community-acquired pneumonia, otitis media, sinusitis). Normally colonises the nasopharynx asymptomatically (carriage: approximately 30-40% in children, 5-10% in adults).

Invasive pneumococcal disease (IPD)
ECDC/WHOPneumococcal infection confirmed by culture or PCR of normally sterile body fluids: blood (bacteraemia); cerebrospinal fluid (meningitis); pleural fluid (empyema); joint fluid (septic arthritis); pericardial fluid. Pneumococcal pneumonia without bacteraemia is NOT classified as IPD. IPD diagnosis requires blood cultures in all patients with suspected bacterial pneumonia or meningitis.

Serotype replacement
ECDC/LancetAfter widespread PCV7 introduction (covering serotypes 4, 6B, 9V, 14, 18C, 19F, 23F), these vaccine serotypes virtually disappeared from carriage and disease — but non-vaccine serotypes expanded to fill the ecological niche. Most important replacement serotypes: 19A (multidrug-resistant; included in PCV13); 3 (not well covered by PCV13 despite inclusion); serotypes 8, 10A, 11A, 12F, 15B, 22F, 33F (included in PCV15/PCV20).

OPSI (overwhelming post-splenectomy infection)
ECDC/BCSHThe spleen is critical for clearing encapsulated bacteria (especially S. pneumoniae, H. influenzae, N. meningitidis) from the bloodstream. Without a spleen (surgical splenectomy, functional asplenia in sickle cell disease), the patient is at lifelong high risk of fulminant septicaemia from encapsulated bacteria. OPSI: abrupt onset of fever and rigors → septicaemia → death within 12-24 hours (case fatality 50-70%). Prevention: PCV20 + PPV23 + MenACWY/MenB vaccination; prophylactic penicillin (lifelong or minimum 2 years); patient education (emergency course of amoxicillin at home, medical alert bracelet).

Dexamethasone in bacterial meningitis
WHO/IDSAIV dexamethasone 0.15mg/kg 6-hourly × 4 days — given before or with the first antibiotic dose — reduces meningitis-related mortality (from approximately 25% to approximately 15% in adults) and neurological sequelae (particularly hearing loss). Mechanism: attenuates the inflammatory cytokine cascade triggered by bacterial lysis after antibiotics. Critical timing: must be given BEFORE or SIMULTANEOUSLY with the first antibiotic dose — no benefit and potentially harmful if given after antibiotics have already been started.

PPV23 (pneumococcal polysaccharide vaccine)
WHO/ACIPThe 23-valent plain polysaccharide vaccine — T-cell independent immune response; provides broader serotype coverage (23 serotypes) but less durable immunity and no booster response. Now recommended to complement PCV20 in adults (especially immunocompromised, asplenic patients). WHO recommended schedule: PCV20 first → PPV23 at least 1 year later (for additional breadth), or PPV23 in adults who previously received PCV13.