A patient with complicated acute myocardial infarction in who coagulase-positive hemolytic staphylococci followed by Pseudomonas aeruginosa were isolated in serial cultures of catheter and blood samplles is reported. The latter was only sensitive to amikacine sulfate and was resistant to other specific antibiotics which have been recently introduced in Cuba. This event evidences the hazard and resistance of the new generations as well as the mutations experienced by these microorganisms. Care to be taken when the patient needs emergency medical instrumentations as puncture s, catheterizations, etc., is emphasized. Assistential institutions must be always prepared in order to prevent or combat infections.