Marty L, Flahault A, Suarez B, Caillon J, Hill C, Andremont A
Service de Microbiologie Médicale, Institut Gustave-Roussy, Villejuif, France.
Intensive Care Med. 1993;19(5):285-9. doi: 10.1007/BF01690549.
To estimate the relation between resistance to methicillin and virulence in strains of Staph. aureus by estimating the survival at day 30.
Case control analysis.
Inpatients at a major Cancer Referral Center.
21 patients with methicillin-resistant Staph. aureus (MRSA) bactaeremia and 45 patients with methicillin-susceptible Staph. aureus (MSSA) bactaeremia, all treated with vancomycin.
Fewer MRSA than MSSA patients were 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 = 0.007). The outcome of the bacteriemic episodes in 14 MRSA and 14 MSSA patients matched for these four factors showed that blood cultures from MRSA patients remained positive significantly longer (p = 0.04), but that survival and length of hospital stay were not significantly different.
These results do not indicate that methicillin-resistance in Staph. aureus is associated with increased virulence.
