Gram negative organisms are main causes of NI (79.8%): Klebsiella (17.1%), Acinetobacter (16.9%), P aeruginosa (16.9%), Enterobacter spp (13.7%), E coli (11.3%); Gram positive bacteria account for 17.0%: S aureus (8.8%), Coagulase negative Staphylococcus (7.3%); Candida is 3.2%.