[Bactericidal activity against P. aeruginosa in serum and bronchial secretion in patients under continuous infusion of azlocillin].

The azlocillin level and killing activity in serum and bronchial secretions against 10 strains of P. aeruginosa were studied in 7 intubated or tracheotomized patients with severe bronchial infection who were receiving the drug as continuous i.v. infusion. In 5 out of 7 patients azlocillin was absent or present only in traces in bronchial secretions in spite of plasma levels ranging between 170 to 340 micrograms/ml. In the other 3 patients azlocillin levels of 23 and 39 micrograms/ml and moderate bactericidal activity against P. aeruginosa could be detected in bronchial secretions. Penicillinase producing strains of Staph. aureus were isolated from the sputum of the 5 patients with extremely low azlocillin level in bronchial secretions. The strain of Staph. aureus isolated from one patient was shown to destroy azlocillin rapidly. In bronchopulmonary infections, Staph. aureus may not only be directly pathogenic but also interfere with the action of beta-lactamase unstable drugs against other microorganisms.