One hundred and forty-three non-repetitive strains of Pseudomonas aeruginosa were collected in 13 French hospitals in 1997. A decreased susceptibility or resistance to ticarcillin (MIC > 16 mg/L) was found in 61 isolates (43%) and this was attributed to three major mechanisms: (i) overexpression of OprM and hence related efflux components such as MexAB or MexXY (42.6%), (ii) production of acqui...

Of the nine efflux systems of the RND (resistance nodulation cell division) family characterized so far in Pseudomonas aeruginosa, four confer significant resistance to antibiotics when overproduced. These systems, namely, MexAB-OprM (ABM), MexCD-OprJ (CDJ), MexEF-OprN (EFN), and MexXY (XY), are individually able to pump out multiple antipseudomonal compounds, including -lactams (ABM, CDJ, XY),...