Exclude the intake year. Add all the positive results (400+250+300+300+250 = 1500). Divide 1500 by the total number of patients from the start of the incidence period, year 1, so 6000 ---> 1500/6000=0.25, this is the average across all 5 years. For annual, divide 0.25 by the number of years, 5 --> 0.25/5 = 0.05 --> 5%.

That's how I got it.

Question asked for gram positive cocci in CHAINS. S. aureus forms clusters, eliminating it. This leaves Enterococcus faecalis and Group A strep. E. faecalis is associated with UTIs.

PDA flows from the Aorta ==> Pulmonary arteries, by passing the RV so there is no change in O2 in the RV.