<prompt> Commonest cause of nosocomial infectionPseudomonasStaphylococciKlebsiellaEnterobacteriacea  <response>: Controversial MCQ, no where there is clear cut reference for MC agent of HAIInitially hospital outbreaks were caused by Gram positive organisms like Streptococcus pyogenes and the methicillin resistant Staphylococcus aureus MRSAPresently Gram negative enteric pathogens Enterobacteriaceae including Escherichia coli, Klebsiella and Enterobacter species have emerged as an important causePseudomonas and Acinetobacter species are also common nosocomial pathogens and are extremely resistant to common antibiotics and antiseptics. 