Figure 1: Some electrophoretic patterns generated by PFGE of MRSA isolated from the outbreak of a second level hospital in Mexico City. M, molecular weight marker lambda ladder, lanes 1, 2, 3, 4, 6 and 9 strains of MRSA isolated from health staff HGMGG (S10, S33, S35, S48, S64 and S91), lanes 5 and 8 strains of MRSA isolated from patients related to infection associated with health care during the study period (2009) (P-5 and P-6), lanes 7 and 10 patients with MRSA strains isolated in 2008 (30-08 and 36-08) and lane 11, control strain (USA 300). At the bottom are observed groups and subgroups belonging to the strains of MRSA.