Lipase activity of Acinetobacter baumannii after treatment with meropenem.

The effects of meropenem (CAS 96036-03-2) at subinhibitory concentrations (sub-MICs; 1/4, 1/8 or 1/16 of the minimal inhibitory concentrations) on the lipase activity of 15 strains of Acinetobacter baumannii were evaluated in vitro. The lipolytic activity was demonstrated by hydrolysis of the substrate Tween 20. Meropenem at the concentrations tested affected the production of bacterial lipase. The degree of induced changes was strain and antibiotic concentration dependent. Eight strains showed an increased lipolytic activity after treatment with meropenem at all three sub-MICs tested; four strains after exposure to two concentrations, and two strains after the treatment with meropenem at one of the concentrations tested. Meropenem at all concentrations reduced the lipase activity only in one strain. In six strains the enzyme activity was decreased only after treatment with some antibiotic concentrations. The possible relevance of increased lipolytic activity in most A. baumannii strains after the effect with meropenem at subinhibitory concentrations has to be clarified by additional studies.