New Methods in the Microbiological Diagnosis of Septicemia

Abstract

Septicemia — the invasion of the bloodstream by bacteria, with all its dreaded complications — continues to be an urgent medical problem that requires close cooperation between the clinician and the laboratory. Although research has improved our knowledge of the subject, septicemia still kills between 30% and 50% of its victims. In this respect, gram-negative septicemia, i. e. septicemia caused by gram-negative rods, is particularly important. In a large hospital in the United States, the following pathogens were isolated from blood cultures in 500 episodes of septicemia (after Weinstein [15]):

Staphylococcus aureus 11%

Escherichia coli 18%

Pneumococci 7%

Klebsiella pneumoniae 6%

Proteus mirabilis 2%

Pseudomonas aeruginosa 6%

Other Enterobacteriaceae 7%

Anaerobes 13%

Fungi 8%

Symptoms suggestive of septicaemia are above all fever, rigors, hypotension or vascular collapse (septic shock), tachypnoea and cardiac arrhythmias. There is usually leucocytosis with a left shift; neutrophils show toxic granulations and Döhle bodies. The platelet count is often decreased, and there may be fragmented red blood cells and disseminated intravascular coagulation (especially in meningococcal septicemia).