Properties of PSE-2 beta-lactamase and genetic basis for its production in Pseudomonas aeruginosa

Abstract

The properties of PSE[Pseudomonas-specific enzyme]-2 .beta.-lactamase were examined by using 2 new PSE-2-producing plasmids, pMG33 and pMG74, and plasmid R151, found in P. aeruginosa. PSE-2 .beta.-lactamase resembled other PSE enzymes in activity against carbenicillin; it also resembled OXA enzymes, such as OXA-1, in rapid hydrolysis of oxacillin, cloxacillin and methicillin and in inhibition by NaCl but not by cloxacillin. Antisera that inactivated TEM-1, TEM-2, OXA-1 or PSE-1 and PSE-4 .beta.-lactamase failed to cross-react with PSE-2, which thus appears to be immunologically distinct. The plasmids determining PSE-2 varied in geographical origin, size, transfer proficiency and incompatibility specificity, all determined resistance to carbenicillin, gentamicin, kanamycin, streptomycin, spectinomycin, sulfonamide and tobramycin. From a pUZ8-R151 recombinant plasmid in Escherichia coli, the PSE-2 .beta.-lactamase gene was transposed to a 2nd plasmid in a 6.4 megadalton unit together with resistance to gentamicin, kanamycin, streptomycin, spectinomycin, sulfonamide and tobramycin. Transposition was recA independent. The designation Tn1404 for this unit, which, like transposons carrying OXA-1; PSE-1, PSE-4 and some transposons determining TEM-1, includes genes for .beta.-lactam, aminoglycoside and sulfonamide resistance.