Clinical evaluation of moxalactam: evidence of decreased efficacy in gram-positive aerobic infections.

Moxalactam was used as initial, empirical therapy in 69 patients with a variety of serious bacterial infections, 32% of which were accompanied by bacteremia. Overall, the success rate was 83% and drug-related adverse effects were minimal. The drug was less efficacious in infections caused by aerobic gram-positive pathogens than it was in those caused by gram-negative pathogens. The following gram-positive organisms were associated with special problems during moxalactam therapy: Streptococcus pneumoniae (development of meningitis and a relapse of pneumonia with a more resistant strain), Staphylococcus epidermidis (in vivo emergence of moxalactam resistance, and the enterococci (failure of therapy and a fatal superinfection. Moxalactam performed well in infections caused by most gram-negative organisms, including aminoglycoside-resistant strains, but the previously reported emergence of gram-negative bacillary resistance to moxalactam during therapy was reconfirmed in our series with Serratia marcescens. The use of moxalactam in the treatment of gram-negative meningitis was further supported by a patient with meningitis-ventriculitis caused by Bacteroides fragilis who was cured with moxalactam after failure on chloramphenicol.