title: Diagnostic microbiology laboratory susceptibility test results discriminate distinctive antibiotic resistance plasmids.
abstract: The sizes of the zones of inhibition around routinely tested antibiotic disks classified gentamicin-resistant isolates of Klebsiella pneumoniae from one hospital into four major antibiotype classes. From each isolate of the prevalent class (A1), two plasmids could be transferred conjugally. One carried genes for resistance to tetracycline, sulfonamides, and chloramphenicol, and for the SHV beta lactamase. The other carried genes for two aminoglycoside-inactivating enzymes, APH (3')-I and AAC (3)-III, for the TEM 1 beta lactamase, and for resistance to sulfonamides. Transconjugants of either plasmid from any A1 isolate yielded the same DNA fragments after restriction endonuclease digestion, but the two plasmids had no fragments in common. Fragments or genes from either plasmid were variously combined or lacking in plasmids from variant isolates (A2, A3, and A4). Plasmids transferable from isolates of classes B and C shared no common DNA restriction fragments with each other or with either plasmid from Class A. Fragments and genes of the plasmids from C isolates, however, were identical with those of a plasmid endemic in a nearby hospital. Routine monitoring by diagnostic microbiology laboratories of distinctive antibiotypes and of the plasmids that produce them would aid infection control and antibiotic usage policy.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D003227:Conjugation, Genetic; D004262:DNA Restriction Enzymes / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D011815:R Factors
chemical_list: D000900:Anti-Bacterial Agents; D004262:DNA Restriction Enzymes