The study will help in identifying the best empiric antibiotic option for Linezolid resistant Vancomycin-resistant Enterococci (VRE) infections. This research is important because it allows the determination of resistance rates to antibiotics that may not be frequently tested to by the clinical microbiology laboratory at UPMC-Presbyterian. It also will provide antibiotic minimum inhibitory concentrations (MICs) for these pathogens which may help in identifying the best empiric antibiotic option for Linezolid-resistant VRE infections.

After 20 linezolid-resistant VRE isolates are identified, genetic relatedness will be determined using a method known as Pulse-field gel electrophoresis (PFGE). No patient related data will accompany these isolates, nor will any related identifiers. These isolates will be tested using standardized susceptibility methods. We will then grow each isolate and test via approved laboratory standards (E-test, AB Biodisk, Stockholm, Sweden) to the drug linezolid. Those determined to be resistant using this approved methodology will be saved until 20 isolates are identified. For resistant isolates found, analytical and molecular techniques will be performed to determine the mechanisms of resistance and whether resistant isolates are coming from a single source/being transmitted from person to person.

Inclusion Criteria:

• Dr. Harrison's laboratory collected the rectal surveillance isolates for infection control purposes. The isolates will be from January 1, 2006 to December 31, 2006.

isolates for rectal surveillance