Molecular epidemiology of transmissible gentamicin resistance among coagulase-negative staphylococci in a cardiac surgery unit.
The prevalence of colonization of patients in a cardiac surgery unit with gentamicin-resistant, coagulase-negative staphylococci increased from 20% to 68% over a period of four years. Gentamicin resistance was found to be plasmid associated and transmissible from wild-type coagulase-negative staphylococcal donors to a Staphylococcus aureus recipient by filter mating (conjugative). These plasmids were present in isolates from 50 (74%) of 69 individuals examined. This figure included isolates from colonized patients, colonized staff, and patients with prosthetic valve endocarditis. A common restriction-endonuclease digestion pattern (pG02; 50 kilobases) was seen in only 19 (38%) of the 50 conjugative plasmids. However, filter hybridization, restriction-endonuclease mapping, and transposon insertional mutagenesis showed that representatives of the other 10 restriction-endonuclease digestion patterns were physically related to pG02 over greater than 80% of their genome, with differences largely due to deletions or insertions of DNA in three areas, and that their gentamicin-resistance genes were identical. Molecular analysis may be required to ascertain the physical similarity among phenotypically and epidemiologically related plasmids.
Archer
G L
GL
Dietrick
D R
DR
Johnston
J L
JL
D006348:Cardiac Surgical Procedures; D003030:Coagulase / Q000378:metabolism; D003227:Conjugation, Genetic; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D004697:Endocarditis, Bacterial / Q000382:microbiology; D005798:Genes, Bacterial; D005839:Gentamicins / Q000494:pharmacology*; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006801:Humans; D009693:Nucleic Acid Hybridization; D010564:Personnel, Hospital; D011815:R Factors; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
D003030:Coagulase; D004251:DNA Transposable Elements; D005839:Gentamicins; D004262:DNA Restriction Enzymes