Invasive pneumococcal disease

Overview

Invasive pneumococcal disease (IPD) is an acute life-threatening infection of the brain or blood stream caused by the bacteria Streptococcus pneumoniae (S. pneumoniae).

Disease epidemiology

Pneumococcal disease occurs worldwide. S. pneumoniae is one of the most common causes of invasive infections such as bacteraemia and meningitis. The highest risk is in young children, the elderly, and those with chronic illness or immunosuppression. The number of identified serotypes is increasing although most infections are still caused by a few serotypes.

The main serotypes have been incorporated into multivalent pneumococcal vaccines. The worldwide emergence of pneumococcal resistance to antibiotics is of concern, as is the replacement of vaccine serotypes by the emergence of non-vaccine serotypes. Pneumococcal vaccination is included in the immunisation schedule for both children and adults.

Pathogen(s)

Streptococcus pneumoniae (S. pneumoniae), also known as pneumococcus.

Transmission

IPD usually requires frequent or prolonged close contact. It primarily transmits through direct deposition of infectious respiratory particles (IRPs) such as when an infected person coughs or sneezes. It can also spread via contact with contaminated surfaces such as when IRPs settle on surfaces or transfer through contact (e.g. handshake) before reaching the mouth, nose or eyes.

Incubation period: Ranging from 1 to 3 days. Exact duration is not well defined as colonisation usually precedes invasive disease.

Infectious period: Presumably infectious as long as pneumococci are present in oro-nasal secretions. With antimicrobial treatment, persons infected with susceptible strains are rendered non-infectious within 24 to 48 hours. However, the main reservoir for transmission is asymptomatic carriers.

Clinical features

Infection is often preceded by a respiratory viral illness before local disease (from congestion and concentration of virulent pneumococci) or invasion leading to systemic or invasive disease that can potentially involve any organ. Clinical manifestations depend on the site of infection. Common clinical syndromes include meningitis and bacteraemia. Pneumococcal pneumonia is not considered an invasive disease unless blood or pleural fluid cultures are positive for the organism. Otitis media is not considered an invasive disease but may be included if S. pneumoniae is isolated from normally sterile middle ear fluid.

Less commonly, IPD can also present as:

• Osteomyelitis

• Pyogenic arthritis

• Endocarditis

• Myocarditis

• Pericarditis

• Bacterial peritonitis

• Endophthalmitis

• Salpingitis

In immunocompromised patients, infections may be fulminant and present with overwhelming sepsis and multiorgan failure.

Risk factors

Risk factors include:

• Persons who are unvaccinated or partially vaccinated

• Persons who have functional or anatomic asplenia/splenic dysfunction

Diagnosis

Detection of S. pneumoniae from a normally sterile body site including blood, and CSF and pleural fluid through isolation.

Treatment and management

Patients will require hospitalisation. Appropriate antibiotics should be given. Empirical antibiotics should be guided by local guidelines before adjusting according to microbiological and susceptibility test results. Source control (e.g. drainage of abscesses) is often critical.

Precaution, prevention, and control

Isolation measures

Standard and droplet precautions should be applied in the healthcare settings.

Contact management

No specific management of contacts is required.

Vaccination

Under the National Childhood Immunisation Schedule, children are recommended to receive 2 primary doses of pneumococcal conjugate (PCV10 or PCV13) at 4 months and 6 months followed by a booster dose at 12 months. For children and adolescents aged between 2 and 17 years old with specific medical condition or indication, they are recommended to receive the pneumococcal polysaccharide (PPSV23).

Under the National Adult Immunisation Schedule, all adults above 65 years old are recommended to receive 1 dose each of PCV13 and PPSV23. Adults aged 18 years old and above with specific medical condition or indication are recommended to receive 1 dose of PCV13 or 1 or 2 doses of PPSV23, depending on indication.

Notification

IPD is a legally notifiable disease in Singapore.

Who should notify:

• Laboratories

When to notify:

• On laboratory confirmation

How to notify:

• Please refer to the Infectious Disease Notification for more information. 

Notification timeline:

• As soon as possible. No later than 72 hours.

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the number of IPD cases in Singapore.

For more information on IPD, please refer to the World Health Organization website.

For general travel advisory, please refer to Health Advice for Travellers.