title: Multidrug-resistant gram-negative bacteria among patients who require chronic hemodialysis.
abstract: OBJECTIVE
  Multidrug-resistant gram-negative bacteria are rapidly spreading throughout the world. The epidemiology of multidrug-resistant gram-negative bacteria in patients who require chronic hemodialysis has not been previously studied.
  
  
  METHODS
  A prospective cohort study of an outpatient hemodialysis unit was conducted. Serial surveillance cultures for multidrug-resistant gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus were collected from patients who were undergoing chronic hemodialysis.
  
  
  RESULTS
  Nineteen (28%) of the 67 enrolled patients were colonized with one or more antimicrobial-resistant bacteria at study enrollment. Eleven (16%), nine (13%), and three (5%) patients were colonized with multidrug-resistant gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus, respectively. Independent risk factors associated with harboring multidrug-resistant gram-negative bacteria at enrollment were residence in a long-term care facility and antibiotic exposure for > or = 7 d in the previous 3 mo. Twenty-two (40%) of 55 patients who had follow-up cultures acquired at least one antimicrobial-resistant bacterium. A total of 20, 15, and 13% of patients acquired multidrug-resistant gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus, respectively. Antibiotic exposure was the only independent risk factor for multidrug-resistant gram-negative bacteria acquisition. Endogenous multidrug-resistant gram-negative bacteria acquisition was detected among 69% of acquired multidrug-resistant gram-negative bacterial strains.
  
  
  CONCLUSIONS
  The prevalence and acquisition of multidrug-resistant gram-negative bacteria surpassed that of vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. Endogenous acquisition, as opposed to patient-to-patient spread, was the predominant mechanism of acquisition. Residence in a long-term care facility and antibiotic exposure may be important factors promoting the spread of multidrug-resistant gram-negative bacteria among this patient population.
authors.affiliation: Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Aurora
authors.initials: A
authors.lastname: Pop-Vicas
authors.forename: James
authors.initials: J
authors.lastname: Strom
authors.forename: Karen
authors.initials: K
authors.lastname: Stanley
authors.forename: Erika M C
authors.initials: EM
authors.lastname: D'Agata
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D002954:Citrobacter / Q000302:isolation & purification; D024901:Drug Resistance, Multiple, Bacterial; D004754:Enterobacter / Q000302:isolation & purification; D016983:Enterococcus / Q000302:isolation & purification; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology / Q000635:transmission; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology / Q000635:transmission; D006801:Humans; D007709:Klebsiella / Q000302:isolation & purification; D016015:Logistic Models; D008134:Long-Term Care / Q000706:statistics & numerical data; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D016017:Odds Ratio; D010044:Outpatient Clinics, Hospital / Q000706:statistics & numerical data; D015995:Prevalence; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D006435:Renal Dialysis; D018570:Risk Assessment; D012307:Risk Factors; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013997:Time Factors; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents