PSE-4 beta lactamase: a serotype-specific enzyme in Pseudomonas aeruginosa.
PSE-4 enzyme is the most common plasmidic beta lactamase in Pseudomonas aeruginosa but its production is invariably non-transferable by conjugation. Of 20 PSE-4+ isolates from 10 separate sources, 16 were serotype O:16 and two belonged to the related O:2(b) serotype. One of the two remaining organisms was not O-typable and the other was agglutinated by several unrelated antisera. Examination of additional O:16 strains confirmed the unusual frequency of PSE-4 enzyme in this serotype. None of the PSE-4+ strains was able to transfer carbenicillin resistance in mating experiments and none contained extrachromosomal DNA. Two explanations of the relationship between enzyme production and O antigenicity are proposed. PSE-4 production may be transmissible, perhaps by transduction, between strains of O:16 or related serotypes, or PSE-4+ P. aeruginosa may represent a disseminated subtype. A third hypothesis, that the PSE-4 coding element carried serotype determinants, was discounted. PSE-4+ and PSE-4- P. aeruginosa strains of O:16 and related serotypes were found to represent a definite cluster by their phage-susceptibility pattern and pyocin type (type 1). The only characters linked to PSE-4 production were resistance to spectinomycin, streptomycin and sulphonamide and the genes responsible for these characters seemed to occur on the PSE-4 coding element.
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002228:Carbenicillin / Q000494:pharmacology; D010403:Penicillin Resistance; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000187:drug effects / Q000201:enzymology*; D011995:Recombination, Genetic; D012703:Serotyping; D013045:Species Specificity; D001618:beta-Lactamases / Q000096:biosynthesis*
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases; D002228:Carbenicillin