Response of Legionella pneumophila to beta-lactam antibiotics.

Legionella pneumophila Philadelphia strain 1 grown in vitro contained five penicillin-binding proteins that were accessible to the antibiotic in membrane preparations and in live cells as well. The bacterium had reasonably low MICs of several beta-lactam antibiotics and was susceptible to both the bactericidal and the lytic activity of these drugs. An unusual feature of the response of this bacterium to penicillin treatment was that cell lysis as determined by decrease in culture turbidity and release of intracellular macromolecules was not accompanied by degradation of the peptidoglycan.