Molecular Epidemiology of MRSA and VRE Co-colonization among Hospitalized Adults in Detroit
Methods: We conducted a prospective study among adult inpatients in six hospitals in and around Detroit, Michigan. Cases were defined as individuals with positive cultures for MRSA and VRE within 7 days of one another. Controls with a positive culture for MRSA and not VRE were matched to cases by hospital, infection type, healthcare associated infection, and requirement for intensive care unit (ICU) care. Patient demographics and clinical data were collected by medical record review. spa typing was conducted by sequencing of the staphylococcal protein a (spa) gene, and sequences were analyzed using DNAGear. Molecular characteristics were compared between matched study groups using generalized estimating equations.
Results: 113 MRSA isolates were analyzed from 83 MRSA and VRE co-colonized case patients and 30 MRSA-only control patients. Isolates were most frequently identified from acute bacterial skin and skin structure infections (46%) and bloodstream infections (17%). The majority of clinical cultures (76%) occurred within 72 hours of admission. The most common spa types were t002 (n=42; 37%), t008 (n=33; 29%) or t1094 (n=12; 11%). The t002 type was significantly more common among co-colonized cases (n=39; 47%) than among MRSA-only controls (n=3; 10%) (p=0.002). Conversely, the t008 type was significantly more common among controls (n=15; 50%) than among cases (n=22; 22%) (p<0.001).
Conclusion: Patients with MRSA and VRE co-colonization were more likely to be infected with USA100-associated type t002. In contrast, patients with MRSA-only were more likely to be infected with USA300-associated type t008. This difference in molecular epidemiology may represent underlying differences in the medical history of patients at risk for co-colonization.
E. T. Martin,
NIH/NIAID: Grant Investigator, Grant recipient
R. Evans, None
J. Mcroberts, None
L. Arrabi, None
A. Pasha, None
P. Lephart, None
M. Rybak, Cubist: Consultant, Grant Investigator and Speaker's Bureau, Consulting fee, Research grant and Speaker honorarium
Forest: Consultant, Grant Investigator and Speaker's Bureau, Consulting fee, Research grant and Speaker honorarium
Theravance: Consultant, Grant Investigator and Speaker's Bureau, Consulting fee, Research grant and Speaker honorarium
Durata: Consultant, Consulting fee
NIH: Investigator, Research grant
K. S. Kaye, Sage: Grant Investigator and Speaker's Bureau, Grant recipient and Speaker honorarium