Significant decrease of gram-negative anaerobic bacteremia in a major hospital from 1967-73 to 1981-89: an effect of the introduction of metronidazole?

Declining rates of anaerobic bacteremia are reported from medical centres all over the world. At Odense University Hospital the frequency of Gram-negative anaerobic bacteremia decreased from 1.62% in 1967-73 to 0.83% in 1981-89 (p < 0.001). Metronidazole prophylaxis prior to bowel surgery seems to be the most important explanation, as the association of Bacteroides bacteremia with surgery decreased from 80% to 48% (p < 0.01) and no cases of Bacteroides bacteremia occurred during metronidazole treatment without the presence of abscess or gangrene. A contributory factor may be improved methods for abscess localization and drainage. Other drugs having an effect on anaerobes seem of minor importance. A new category of patients seems to be those who have undergone aorto-femoral bypass operation for aneurysm of the aorta. They contract anaerobic Gram-negative bacteremia from infected hematomas or intestinal gangrene.