Relative contribution of Prevotella intermedia and Pseudomonas aeruginosa to lung pathology in airways of patients with cystic fibrosis.
BACKGROUND
Patients with cystic fibrosis (CF) with Pseudomonas aeruginosa lung infections produce endobronchial mucus plugs allowing growth of obligate anaerobes including Prevotella spp. Whether obligate anaerobes contribute to the pathophysiology of CF lung disease is unknown.


METHODS
The virulence of Prevotella intermedia and Ps aeruginosa was investigated in vitro and in mice, antibodies against P intermedia in CF sera were assessed and a culture-independent detection method for P intermedia/P nigrescens in CF sputum was tested.


RESULTS
P intermedia reached cell numbers of >10(5)->10(7)&emsp14;colony-forming units (CFU)/ml sputum. The majority of patients with CF (16/17; 94.1%) produced antibodies against two immunoreactive antigens of P intermedia. Culture supernatant fluids, collected from 10(9) P intermedia cells, were more cytotoxic to respiratory epithelial cells in vitro and inflammatory in mouse lungs than respective fluids from anaerobically grown Ps aeruginosa, while fluids from aerobically grown Ps aeruginosa had the highest cytotoxicity and inflammation. Both pathological effects were largely reduced when culture supernatant fluids from 10(7) cells of either species were used. P intermedia cells (∼10(6)CFU/lung) did not induce mortality in the agar beads lung infection mouse model, while Ps aeruginosa cells caused death in 30% of mice due to rapid multiplication. A P intermedia/P nigrescens-specific PNA probe was significantly more sensitive than culture-dependent diagnostic assays to detect these strict anaerobes.


CONCLUSIONS
Ps aeruginosa and P intermedia become significantly virulent in vitro and in vivo when cell numbers exceed 10(8) CFU/lung.
Ulrich
Martina
M
Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany.
Beer
Isabelle
I
Braitmaier
Peter
P
Dierkes
Michaela
M
Kummer
Florian
F
Krismer
Bernhard
B
Schumacher
Ulrike
U
Gräpler-Mainka
Ute
U
Riethmüller
Joachim
J
Jensen
Peter Ø
PØ
Bjarnsholt
Thomas
T
Høiby
Niels
N
Bellon
Gabriel
G
Döring
Gerd
G
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D016866:Bacteroidaceae Infections / Q000150:complications*; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D003550:Cystic Fibrosis / Q000150:complications*; D006801:Humans; D008168:Lung / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009894:Opportunistic Infections / Q000150:complications; D018713:Prevotella intermedia / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity*; D011552:Pseudomonas Infections / Q000150:complications*; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity*; D012141:Respiratory Tract Infections / Q000150:complications; D013183:Sputum / Q000382:microbiology; D014774:Virulence
D000907:Antibodies, Bacterial