Human pleural fluid is a potent growth medium for Streptococcus pneumoniae

Natalia D Popowicz; Sally M Lansley; Hui M Cheah; Ian D Kay; Christine F Carson; Grant W Waterer; James C Paton; Jeremy S Brown; Y C Gary Lee

doi:10.1371/journal.pone.0188833

Human pleural fluid is a potent growth medium for Streptococcus pneumoniae

PLoS One. 2017 Nov 30;12(11):e0188833. doi: 10.1371/journal.pone.0188833. eCollection 2017.

Authors

Natalia D Popowicz^{1

2

3}, Sally M Lansley³, Hui M Cheah³, Ian D Kay⁴, Christine F Carson², Grant W Waterer^{2

5}, James C Paton⁶, Jeremy S Brown⁷, Y C Gary Lee^{2

3

8}

Affiliations

¹ Pharmacy Department, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.
² Division of Medicine, University of Western Australia, Perth, Western Australia, Australia.
³ Institute for Respiratory Health, University of Western Australia, Perth, Western Australia, Australia.
⁴ Department of Microbiology and Infectious Diseases, PathWest Laboratory Medicine, Royal Perth Hospital, Perth, Western Australia, Australia.
⁵ Respiratory Department, Royal Perth Hospital, Perth, Western Australia, Australia.
⁶ Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, South Australia, Australia.
⁷ Centre for Inflammation and Tissue Repair, Respiratory Medicine, University College London, London, England.
⁸ Respiratory Department, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.

Abstract

Empyema is defined by the presence of bacteria and/or pus in pleural effusions. However, the biology of bacteria within human pleural fluid has not been studied. Streptococcus pneumoniae is the most common cause of pediatric and frequent cause of adult empyema. We investigated whether S. pneumoniae can proliferate within human pleural fluid and if growth is affected by the cellular content of the fluid and/or characteristics of pneumococcal surface proteins. Invasive S. pneumoniae isolates (n = 24) and reference strain recovered from human blood or empyema were inoculated (1.5×106CFU/mL) into sterile human malignant pleural fluid samples (n = 11). All S. pneumoniae (n = 25) strains proliferated rapidly, increasing by a median of 3009 (IQR 1063-9846) from baseline at 24hrs in all pleural effusions tested. Proliferation was greater than in commercial pneumococcal culture media and concentrations were maintained for 48hrs without autolysis. A similar magnitude of proliferation was observed in pleural fluid before and after removal of its cellular content, p = 0.728. S. pneumoniae (D39 strain) wild-type, and derivatives (n = 12), each with mutation(s) in a different gene required for full virulence were inoculated into human pleural fluid (n = 8). S. pneumoniae with pneumococcal surface antigen A (ΔpsaA) mutation failed to grow (2207-fold lower than wild-type), p<0.001, however growth was restored with manganese supplementation. Growth of other common respiratory pathogens (n = 14) across pleural fluid samples (n = 7) was variable and inconsistent, with some strains failing to grow. We establish for the first time that pleural fluid is a potent growth medium for S. pneumoniae and proliferation is dependent on the PsaA surface protein and manganese.

MeSH terms

Empyema, Pleural / microbiology*
Humans
Pleural Effusion / microbiology*
Streptococcus pneumoniae / growth & development*
Streptococcus pneumoniae / pathogenicity

Grants and funding

YCGL is a National Health & Medical Research Council (NHMRC) Career Development Fellow and receives project grant funding from the NHMRC, New South Wales Dust Disease Board (DDB), Sir Charles Gairdner Research Advisory Committee, Institute for Respiratory Health Westcare Alan King Grants and the Cancer Council of Western Australia. JSB is partially funded from the Department of Health’s NIHR Biomedical Research Centre’s funding scheme. JCP is a NHMRC Senior Principal Research Fellow. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.