ROLE OF PORINS IN THE ANTIBIOTIC SUSCEPTIBILITY OF PSEUDOMONAS-AERUGINOSA - CONSTRUCTION OF MUTANTS WITH DELETIONS IN THE MULTIPLE PORIN GENES

We inserted deletions in the chromosomal genes of Pseudomonas aerugino sa coded for the outer membrane porins, proteins C, D2, or E1, and all possible combinations of these proteins by the gene replacement techn ique and selecting for imipenem-resistance. Determination of the minim um inhibitory concentrations of beta-lactams, fluoroquinolones, chlora mphenicol and gentamicin in these mutants revealed that most mutants s howed equal susceptibility to the porin-sufficient strain. The only ex ception was that imipenem and meropenem showed increased minimum inhib itory concentrations in all of the mutants lacking protein D2. These r esults firmly established that the P. aeruginosa porins identified so far form the pores do not accommodate the passage of most antipseudomo nal antibiotics, with the exception of carbapenems. (C) 1995 Academic Press, Inc.