Hospitals are becoming safer for very sick children, according to a new study that found steep declines in dangerous infections sometimes transmitted through treatments in intensive care units.

The results from 174 U.S. hospitals in 39 states suggest increasing efforts to improve patient safety and reduce preventable health-care linked infections are working, the study authors said.

"The bottom line is it's safer to have a hospitalized child today than it was five years ago," said study author Dr. Stephen Patrick, a Vanderbilt University pediatrician and public health researcher.

The study involved infections spread through breathing machines and central lines — intravenous catheters used long-term to deliver medicine or fluids deep into the bloodstream. The devices can be contaminated with bacteria and other germs when doctors and nurses don't adequately wash their hands and through other lax hygiene practices.

The study found declines between 2007 and 2012. For central line infections, the rate dropped from just under five infections per 1,000 days of use to about one. For ventilator infections, it fell from just under two per 1,000 days to less than one.

Dr. Peter Pronovost, a Johns Hopkins Medicine patient safety expert, called the results "spectacular and commendable." He was not involved in the research.

The study was published Monday in Pediatrics.