The Journal of Thoracic and Cardiovascular Surgery, Vol 89, 42-49, Copyright © 1985 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Effect of hemothorax on experimental empyema thoracis in the guinea pig
C Mavroudis, BL Ganzel, S Katzmark and HC Polk Jr
An experimental model for empyema thoracis in the Duncan-Harley guinea pig
is introduced. Empyema thoracis development and early death (less than 14
days after bacterial inoculation) were noted after various concentrations
and species were inoculated into the pleural space with a piece of
umbilical tape, which was used as a cofactor. The effect of concomitant
hemothorax was also tested. Group I (N = 90) had intrapleural inoculation
of umbilical tape and various concentrations (10(4), 10(6), 10(8)
organisms/ml) of various bacterial species, which included Staphylococcus
aureus (N = 30), Escherichia coli (N = 30), and Bacteroides fragilis (N =
30). Group II (N = 90) had intrapleural inoculation of umbilical tape, 1 ml
of autologous blood, and the same varying concentrations and species of
bacteria as Group I. The observation period was 14 days, during which time
early deaths were noted. Fifty-eight percent of the staphylococcal group of
animals, 37% of the E. coli group of animals, and none of the B. fragilis
group of animals developed empyema. Animals with empyema developed
significant weight loss (p less than 0.05) and roentgenographic evidence of
empyema, which was supported by postmortem pleural reaction and pneumonia
scores (p less than 0.05). Higher concentrations of inoculated bacteria
produced a higher incidence of empyema in the S. aureus and E. coli groups
(p less than 0.05), but concomitant hemothorax did not increase the already
high incidence of empyema and early death in the E. coli group. Empyema
caused by B. fragilis did not develop, even with cofactors of umbilical
tape and blood. Anaerobic infections in this model may require the presence
of other aerobic or facultative organisms, the presence of necrotic lung,
prior malnutrition, or a combination thereof.
