Invasive pneumococcal disease

Notification requirement for invasive pneumococcal disease

Invasive pneumococcal disease is a ‘routine’ notifiable condition and must be notified by medical practitioners and pathology services in writing within 5 days of diagnosis.

This is a Victorian statutory requirement.

Primary school and children’s services centre exclusion for invasive pneumococcal disease

Because invasive pneumococcal disease comes under the heading of streptococcal infection (including scarlet fever), the case is to be excluded until the child has received antibiotic treatment for at least 24 hours and feels well. Occasionally, invasive pneumococcal disease can manifest as meningitis. In such circumstances, a child should be excluded as for bacterial meningitis. In this instance, the child is to be excluded until well.

Infectious agent of invasive pneumococcal disease

Streptococcus pneumoniae is a gram-positive Streptococcus of which 90 serotypes are known to cause disease. Worldwide, approximately 23 serotypes account for the majority of infections.

Identification of invasive pneumococcal disease

Clinical features

Invasive pneumococcal disease commonly presents as septicaemia, meningitis and pneumonia. Septicaemia and meningitis are more common in children (with the exception of Aboriginal children, who present most commonly with pneumonia), while pneumonia is more frequent in adults. Other less common clinical presentations include otitis externa, sinusitis, septic arthritis, peritonitis, pleurisy, endocarditis and pericardial abscess.

Diagnosis

Diagnosis is via isolation of the organism by culture or nucleic acid detection methods (polymerase chain reaction – PCR) from a normally sterile site (e.g. blood or cerebrospinal fluid). Rapid antigen detection tests are available, but they are of limited use in the diagnosis of invasive disease in children because of the frequency of pharyngeal pneumococcal carriage. Although an excellent point-of-care test for clinical diagnosis of pneumococcal infection (sensitivity 70–92 per cent; specificity >90 per cent) urinary antigen (BinaxNOW), theresults do not meet the national guidelines for confirmation of invasive disease.

Incubation period of Streptococcus pneumoniae

The incubation period is 1–3 days.

Public health significance and occurrence of invasive pneumococcal disease

S. pneumoniae is one of the most common causes of bacterial meningitis, septicaemia and pneumonia worldwide. Indigenous children in central Australia have the highest reported rates of invasive pneumococcal disease worldwide. The overall incidence rate in Victoria is approximately 9 per 100,000 population per year, with an overall case-fatality rate approaching 8 per cent. Rates of disease are highest in children aged less than 2 years, and people aged 65 years and over.

The prevalence of antibiotic resistance is increasing. Approximately 28 per cent of isolates in 2005 in Australia were non-penicillin susceptible, and 5 per cent were resistant to third-generation cephalosporins. The prevalence of antibiotic resistance differs by state and territory.

Reservoir of Streptococcus pneumoniae

S. pneumoniae is commonly found in the upper respiratory tract of humans.

Mode of transmission of Streptococcus pneumoniae

The organism is transmitted by respiratory droplets, direct oral contact, or indirect contact through articles freshly soiled with respiratory discharges. Person-to-person transmission of the organism leading to infection is infrequent, as many factors intervene between acquisition of the organism, colonisation and development of disease.

Pneumococci are commonly found in the upper respiratory tract of healthy people worldwide. Such colonisation does not normally result in infection because the pathogens are destroyed by normal nasopharyngeal flora. When a person’s normal mechanisms of immunity are impaired, invasive disease can occur.

It is believed that peak incidence of S. pneumoniae colonisation occurs in children at 3 years of age. Incidence of asymptomatic nasopharyngeal carriage then decreases with age until 10 years of age, after which prevalence rates remain stable.

Period of communicability of invasive pneumococcal disease

Bacteria are communicable in respiratory infections until discharges from the mouth and nose no longer contain virulent pneumococci in significant numbers. Appropriate antibiotics render patients with susceptible strains noninfectious within 24–48 hours.

Susceptibility and resistance to invasive pneumococcal disease

Everyone is susceptible to infection; however, the risk of invasive disease is highest for those aged less than 2 years and the elderly. Other risk factors include prematurity and low birth weight, immunosuppressive therapy, and exposure to tobacco smoke. Conditions or illnesses such as asplenia, sickle cell disease, cardiovascular disease, diabetes mellitus, cirrhosis, Hodgkin’s disease, hypogammaglobulinaemia, lymphoma, multiple myeloma, renal failure, neutropenia, nephrotic syndrome, HIV infection and recent organ transplant are also risk factors for infection. Indigenous people in all age groups have higher rates of invasive disease. Immunity is thought to be serotype specific.

Control measures for invasive pneumococcal disease

Preventive measures

There are currently two different types of pneumococcal vaccine in use in Victoria:

• 13-valent pneumococcal conjugate vaccine (13vPCV), which replaced the 7-valent pneumococcal conjugate (7vPCV) on 1 July 2011 and protects against an additional six pneumococcal serotypes
• 23-valent pneumococcal polysaccharide vaccine (23vPPV).

The 13vPCV is available free for the following groups:

• infants aged 2, 4 and 6 months as part of their primary three-dose course of childhood pneumococcal vaccination
• children at 12 months of age with medical risk conditions
• catch-up dose(s) for children up to 2 years of age (number of doses and spacing of intervals depend on the age at commencement).

The 23vPPV is available free for the following people:

• people aged 65 years
• Aboriginal and Torres Straight Islander people from 50 years of age
• Aboriginal and Torres Straight Islander people aged 15–49 years with underlying medical risk conditions
• children aged 4–5 years with medical risk conditions (including if they were born at less than 28 weeks gestation).

For detailed information on vaccine schedules and recommendations, including the medical risk conditions and catch-up recommendations, please see the current edition of the Australian immunisation handbook. One of the listed medical risk conditions predisposing people to invasive pneumococcal disease is asplenia (either functional, including sickle cell disease, or anatomical). The Spleen Registry at the Alfred Hospital can provide additional support.

In addition to vaccination, public health risk mitigation measures include observing cough etiquette and timely, appropriate treatment.

Control of case

Penicillin remains the treatment of choice until antibiotic sensitivities are obtained. Patients who are allergic to penicillin may be given cephalosporins. Dosage and administration are dependent on clinical acuity and site of infection. Attempt to obtain blood or cerebrospinal fluid specimens before commencing therapy. Treatment should not, however, be delayed in children and infants, particularly if the clinical presentation suggests septicaemia or meningitis. Consult the current version of Therapeutic guidelines: antibiotic.

Control of contacts

Investigation of contacts is of no practical value.

Control of environment

Disinfect or destroy articles contaminated with discharges from the nose and throat, or from other infected sites.

Outbreak measures for invasive pneumococcal disease

In the very rare situation of an outbreak in an institution or other closed population groups, immunisation could be considered if the implicated serotype is contained in the 13vPCV and/or 23vPPV.