title: Co-colonization with multiple different species of multidrug-resistant gram-negative bacteria.
abstract: BACKGROUND
  The characteristics of co-colonization with multiple different species of multidrug-resistant gram-negative bacteria (MDRGN) have not been fully elucidated. Quantifying the prevalence of co-colonization and those patients at higher risk of co-colonization may have important implications for strategies aimed at limiting the spread of MDRGN.
  
  
  METHODS
  To determine the prevalence of MDRGN colonization, rectal swabs were obtained from 212 residents residing in a 600-bed long-term care facility. Co-colonization was defined as colonization with ≥2 different MDRGN species. Co-colonized residents were compared with residents colonized with a single MDRGN species to identify factors associated with an increased risk for co-colonization. Molecular typing was performed to determine the contribution of cross transmission to the co-colonized state.
  
  
  RESULTS
  A total of 53 (25%) residents was colonized with ≥1 MDRGN. Among these, 11 (21%) were colonized with ≥2 different species of MDRGN. A global deterioration score of ≥5 representing advanced dementia and an increased requirement for assistance from health care workers was significantly associated with co-colonization (P = .05). Clonally related MDRGN strains were identified among 7 (64%) co-colonized residents.
  
  
  CONCLUSIONS
  The prevalence of co-colonization with ≥2 different MDRGN is substantial. Cross transmission of MDRGN is a major contributor to the co-colonized state.
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, MA 02215, USA. gsnyder@bidmc.harvard.edu
authors.forename: Graham M
authors.initials: GM
authors.lastname: Snyder
authors.forename: Erin
authors.initials: E
authors.lastname: O'Fallon
authors.forename: Erika M C
authors.initials: EM
authors.lastname: D'Agata
mesh_terms: D000369:Aged, 80 and over; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D016000:Cluster Analysis; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006090:Gram-Negative Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology*; D006801:Humans; D008297:Male; D058889:Molecular Typing; D015995:Prevalence; D012007:Rectum / Q000382:microbiology; D012307:Risk Factors