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Thorax 65:985-990 doi:10.1136/thx.2009.132845
  • Cystic fibrosis

Value of serology in predicting Pseudomonas aeruginosa infection in young children with cystic fibrosis

  1. on behalf of the members of AREST CF and the ACFBAL Trial
  1. 1Department of Respiratory Medicine, Princess Margaret Hospital for Children, Perth, Western Australia, Australia
  2. 2Telethon Institute for Child Health Research and Centre for Child Health Research, University of Western Australia, Perth, Western Australia, Australia
  3. 3Queensland Children's Respiratory Centre, Royal Children's Hospital, Queensland, Australia
  4. 4Queensland Children's Medical Research Institute, The University of Queensland, Royal Children's Hospital, Brisbane, Queensland, Australia
  5. 5Queensland Paediatric Infectious Disease Laboratory, Royal Children's Hospital, Queensland, Australia
  1. Correspondence to Dr Tonia Douglas, Department of Respiratory Medicine, Princess Margaret Hospital for Children, Roberts Road, Subiaco, Perth, WA 6008, Australia; tonia.douglas{at}health.wa.gov.au
  • Received 7 December 2009
  • Accepted 23 July 2010
  • Published Online First 1 October 2010

Abstract

Background Early detection of Pseudomonas aeruginosa is essential for successful eradication. The accuracy of serum antibodies against specific and multiple P aeruginosa antigens at predicting lower airway infection in young children with cystic fibrosis (CF) was investigated.

Methods A commercial P aeruginosa multiple antigen (MAg) ELISA and an in-house exotoxin A (ExoA) ELISA were compared in two populations: a discovery population of 76 children (0.1–7.1 years) undergoing annual bronchoalveolar lavage (BAL)-based microbiological surveillance and a test population of 55 children (0.1–5.6 years) participating in the Australasian CF Bronchoalveolar Lavage Trial.

Results In the discovery population, P aeruginosa was cultured from BAL fluid (≥105 colony-forming units (cfu)/ml) in 15/76 (19.7%) children (median age 1.88 years). Positive MAg and ExoA serological results were found in 38 (50.0%) and 30 (39.5%) children, respectively. Positive (PPV) and negative (NPV) predictive values for serology at diagnosing P aeruginosa infection (≥105 cfu/ml) were 0.14 and 0.99 respectively (MAg assay) and 0.11 and 0.98 (ExoA assay). In the test population, P aeruginosa was cultured from BAL fluid (≥105 cfu/ml) in 16/55 (29.1%) children (median age 1.86 years) and from oropharyngeal swabs in 32/36 (88.9%). Positive MAg and ExoA serology was detected in 19 (34.5%) and 33 (60.0%) children, respectively. The PPV and NPV of serology were 0.26 and 0.94 respectively (MAg assay) and 0.19 and 0.98 (ExoA assay) and were marginally higher for oropharyngeal cultures.

Conclusions Measuring serum antibody responses against P aeruginosa is of limited value for detecting early P aeruginosa infection in young children with CF.

Footnotes

  • Members of the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF): E Balding, L Berry, S Brennan, C Calogero, R Carzino, N De Klerk, T A Douglas, C Gangell, L Garratt, G Hall, A Kicic, I Laing, B Linnane, J Massie, L Mott, D Mullane, C Murray, G Nolan, N Pillarisetti, S Ranganathan, C Robertson, P Robinson, B Skoric, P D Sly, S M Stick, E Sutanto. Members of the Australasian Cystic Fibrosis Bronchoalveolar Lavage (ACFBAL) study: D S Armstrong, C A Byrnes, J B Carlin, D M Cooper, P J Cooper, C J Dakin, P W Francis, K Grimwood, A J Martin, R J Massie, I B Masters, L K Patterson, S Ranganathan, C F Robertson, I F Robertson, P J Robinson, S Vidmar, C E Wainwright, B F Whitehead.

  • Funding Australian Cystic Fibrosis Research Trust and National Health and Medical Research Council of Australia.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Princess Margaret Hospital for Children ethics committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.


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