Species for which acquired resistance may be a problem Aerobic Gram-positive bacteria Staphylococcus aureus methicillin resistant (MRSA)+ Streptococcus pyogenes* Aerobic Gram- negative bacteria Haemophilus influenzae$* Haemophilus parainfluenzae$ Inherantly resistant organisms Aerobic Gram- negative bacteria Acinetobacter Enterobacteriaceae Pseudomonas