Pleural fluid nucleic acid testing enhances pneumococcal surveillance in children

Authors


  • Conflict of Interest statement: This study was funded through an unrestricted grant from GlaxoSmithKline, Belgium.

Adam Jaffe, Department of Respiratory Medicine, Sydney Children's Hospital, High Street, Randwick, Sydney NSW 2031, Australia. Email: adam.jaffe@sesiahs.health.nsw.gov.au

ABSTRACT

Background and objective:  National surveillance of invasive pneumococcal disease (IPD) includes serotyping Streptococcus pneumoniae (SP) isolates from sterile site cultures. PCR is more sensitive and can identify more SP serotypes (STs) in culture-negative samples. The aim of this study was to determine whether enhanced surveillance of childhood empyema, using PCR, provides additional serotype information compared with conventional surveillance.

Methods:  Pleural fluid (PF) from children with empyema were cultured and tested by PCR to identify SP, targeting the autolysin gene (lytA). Multiplex PCR-based reverse line blot assay was used to identify SP STs. Corresponding IPD surveillance and serotype data were obtained from the National Notifiable Diseases Surveillance System (NNDSS).

Results:  Eighty-nine children with empyema, aged ≤16 years, were recruited between April 2008 and March 2009, inclusive. SP was isolated from 5/84 (5.9%) PF cultures and by PCR in 43/79 (54.4%) PF samples. Serotypes were unidentifiable in 15 samples. The frequency of six serotypes (or serotype pairs) identified in 28 samples, including one with two serotypes, were: ST1, n = 4/29 (13.8%); ST3, n = 9/29 (31.0%); ST19A, n = 12/29 (41.4%); ST7F/7A, n = 1/29 (3.4%); ST9V/9A, n = 1/29 (3.4%); ST22F/22A, n = 2/29 (6.9%). Over the same period, 361 IPD patients, aged 16 years or less, were notified to NNDSS. Among 331 serotypeable NNDSS isolates (71.5% from blood), the frequencies of ST1 and 3 were significantly lower than in PF samples: ST1, n = 8/331 (2.4%; P < 0.05); ST3, n = 13/331 (3.9%; P < 0.0001).

Conclusions:  The use of PCR to identify and serotype SP in culture-negative specimens provides additive information.

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