Augmented effect of early antibiotic treatment in mice with experimental lung infections due to sequentially adapted mucoid strains of Pseudomonas aeruginosa.
BACKGROUND
Effects of treatment with tobramycin initiated 1 or 24 h post-infection were investigated in a new version of a pulmonary infection model in mice. The model reflects the differentiated behaviour of Pseudomonas aeruginosa mucoid strains isolated from the lungs of one chronically infected cystic fibrosis (CF) patient at different time periods during chronic lung infection.


METHODS
BALB/c mice were challenged with alginate-embedded mucoid clinical isolates isolated in 1988, 1997 or 2003. Mice were euthanized on day 1, 2 or 3 post-infection for estimation of quantitative bacteriology, histopathology, and measurement of granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory protein 2 (MIP-2).


RESULTS
There was a significant reduction of bacteria when comparing treatment initiated 1 h post-infection with treatment initiated after 24 h for isolates 1997 and 2003. Treatment initiated 1 h post-infection also resulted in a reduction of the pulmonary cytokines G-CSF, for all three isolates, and MIP-2, for isolates 1997 and 2003. Histological evaluation showed a shift from the acute-type inflammatory immune response to a chronic-type in mice infected with isolate 2003.


CONCLUSIONS
A significant reduction in the number of bacteria was observed when initiating treatment 1 h post-infection compared with initiating treatment after 24 h, although the latest isolate avoided complete clearance. Early antibiotic treatment directed at the mucoid phenotype in mice also reduced the inflammation and, thereby, the lung tissue damage.
van Gennip
Maria
M
Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark. mvg@sund.ku.dk
Moser
Claus
C
Christensen
Louise D
LD
Bjarnsholt
Thomas
T
Calum
Henrik
H
Jensen
Peter Ø
PØ
Christophersen
Lars
L
Hougen
Hans Petter
HP
Ciofu
Oana
O
Molin
Søren
S
Givskov
Michael
M
Høiby
Niels
N
D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D054426:Chemokine CXCL2 / Q000032:analysis; D015169:Colony Count, Microbial; D003550:Cystic Fibrosis / Q000150:complications; D004195:Disease Models, Animal; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000032:analysis; D006801:Humans; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D018410:Pneumonia, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D012720:Severity of Illness Index; D013997:Time Factors; D014031:Tobramycin / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D054426:Chemokine CXCL2; D016179:Granulocyte Colony-Stimulating Factor; D014031:Tobramycin