RESISTANCE TO METHICILLIN AND VIRULENCE OF STAPHYLOCOCCUS-AUREUS STRAINS IN BACTEREMIC CANCER-PATIENTS

Objective. To estimate the relation between resistance to methicillin and virulence in strains of Staph. aureus by estimating the survival a t day 30. Design: Case control analysis. Setting: Inpatients at a majo r Cancer Referral Center. Patients. 21 patients with methicillin-resis tant Staph. aureus (MRSA) bactaeremia and 45 patients with methicillin -susceptible Staph. aureus (MSSA) bactaeremia, all treated with vancom ycin. Measurements and main results. Fewer MRSA than MSSA patients wer e neutropenic (p = 0.04), but more MRSA patients were hospitalized in intensive care units (p = 0.03), had had surgical episodes (p = 0.06). MRSA patients also had more microbiological samples cultured (p = 0.0 07). The outcome of the bacteriemic episodes in 14 MRSA and 14 MSSA pa tients matched for these four factors showed that blood cultures from MRSA patients remained positive significantly longer (p = 0.04), but t hat survival and length of hospital stay were not significantly differ ent. Conclusions. These results do not indicate that methicillin-resis tance in Staph. aureus is associated with increased virulence.