Content Source:
Office of Public Health Data, Surveillance, and Technology
Invasive Pneumococcal Disease (IPD) (Streptococcus pneumoniae)
2017 Case Definition
Invasive Pneumococcal Disease (IPD) (Streptococcus pneumoniae)
2017 Case Definition
2017 Case Definition
CSTE Position Statement(s)
- 16-ID-08
Background
Invasive pneumococcal disease (IPD) is a notable cause of morbidity and mortality in the US,
despite the availability of 7-valent pneumococcal conjugate vaccine (PCV7) and 13-valent pneumococcal
conjugate vaccine (PCV13). After introduction of PCV7 in 2000, rates were reduced by 64-77% among adults
and older children, and down to less than one case per 100,000 among children under 5 for the included
serotypes. In 2010, PCV13 further lowered rates. However, in 2011 there were still more than 35,000 cases
and 4,200 deaths from IPD, indicating a need for continued surveillance.
The ability to test for Streptococcus pneumoniae using culture independent diagnostic tests (CIDTs)
like polymerase chain reaction (PCR)-based testing has become both more available and more common.
PCR can be and is used for typing of Streptococcus pneumoniae, a key component of surveillance, and
integrating CIDT identification into the case definition would increase overall coherence. Similar
to the convention with other diseases, it is therefore suggested that a category of “probable” IPD
cases be created, to classify CIDT positive but culture negative (or with absent culture results)
individuals.
Clinical Criteria
Invasive Pneumococcal (Streptococcus pneumoniae) Disease or IPD causes many clinical syndromes,
depending on the site of infection (e.g., bacteremia, meningitis.)
Laboratory Criteria For Diagnosis
Supportive: Identification of S. pneumoniae from a normally sterile body site by a CIDT without
isolation of the bacteria.
Confirmatory: Isolation of S. pneumoniae from a normally sterile body site.
Epidemiologic Linkage
Not required.
Criteria to Distinguish a New Case from an Existing Case
A single case should be defined as a health event with a specimen collection date that occurs
more than 30 days from the last known specimen with a positive lab finding.
Case Classification
Probable
A case that meets the supportive laboratory evidence.
Confirmed
A case that meets the confirmatory laboratory evidence.
Comments
The use of CIDTs as stand-alone tests for the direct detection of S. pneumoniae from
clinical specimens is increasing. Data regarding their performance indicate variability in the
sensitivity, specificity, and positive predictive value of these assays depending on the
manufacturer and validations methods used. It is therefore useful to collect information on the
laboratory conducting the testing, and the type and manufacturer of the CIDT used to diagnose
each IPD case. Culture confirmation of CIDT-positive specimens is still the ideal method of
confirming a case of IPD.