title: Low-level colonization of hospitalized patients with methicillin-resistant coagulase-negative staphylococci and emergence of the organisms during surgical antimicrobial prophylaxis.
abstract: By use of techniques that have been developed to detect small numbers of methicillin-resistant staphylococci, we cultured samples from the nares and subclavian and inguinal areas of 29 patients before and after cardiac surgery and 10 patients before and after coronary angioplasty. Methicillin-resistant coagulase-negative staphylococci were recovered before the surgical or angioplasty procedure from 74% of patients. The quantitative recovery of methicillin-resistant isolates before cardiac surgery or coronary angioplasty was compared with the number of methicillin-resistant staphylococci detected at the same site 3 days after the procedure. In cardiac surgery patients (who received antibiotic prophylaxis), 17 of the 28 sites (61%) in which low-level colonization with methicillin-resistant strains was detected preoperatively contained high levels of methicillin-resistant staphylococci postoperatively. In contrast, coronary angioplasty patients (who did not receive antibiotic prophylaxis) did not have any of the 14 sites containing low levels of methicillin-resistant strains before angioplasty emerge to harbor high levels of methicillin-resistant staphylococci after angioplasty. Methicillin-resistant coagulase-negative staphylococci from each site in which high levels of methicillin-resistant staphylococci emerged postoperatively were paired with preoperative isolates from the same site. Identical antibiograms and plasmid profile patterns were demonstrated for seven of the pre- and postoperative isolate pairs, suggesting that the high levels of methicillin-resistant coagulase-negative staphylococci detected on the skin or in the nares after cardiac surgery were derived from methicillin-resistant organisms present at the site preoperatively in much smaller numbers.
authors.affiliation: Saint Thomas Hospital, Nashville, Tennessee 37202.
authors.forename: D S
authors.initials: DS
authors.lastname: Kernodle
authors.forename: N L
authors.initials: NL
authors.lastname: Barg
authors.forename: A B
authors.initials: AB
authors.lastname: Kaiser
mesh_terms: D000800:Angioplasty, Balloon; D006348:Cardiac Surgical Procedures; D002511:Cephalosporins / Q000627:therapeutic use*; D003030:Coagulase; D005838:Genotype; D006801:Humans; D008712:Methicillin / Q000494:pharmacology; D010403:Penicillin Resistance; D010641:Phenotype; D010957:Plasmids; D011183:Postoperative Complications / Q000453:epidemiology* / Q000517:prevention & control; D011292:Premedication; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000517:prevention & control; D013210:Staphylococcus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*
chemical_list: D002511:Cephalosporins; D003030:Coagulase; D008712:Methicillin