Intensive care patients are seven times more likely to become infected with the MRSA superbug when units are suffering nursing shortages compared to when they are fully-staffed, researchers said today.
A study of one eight-bed intensive care unit over a five-month period concluded that a lack of trained nurses could be linked to higher levels of the deadly infection.
Experts said a combination of factors, including poor hygiene as well as staff shortages, influenced infection rates.
Hospital acquired infections and hospital cleanliness have been key issues in the election campaign, with all major parties pledging to crack down on rising rates and toughen up on hygiene.
The latest study, presented at the Intensive Care Society's annual spring meeting, looked at 174 patients admitted to the unit over 23 weeks.
Of these patients, 7% acquired MRSA during seven of the weeks studied.
During six of these seven weeks the unit was particularly busy because of a shortage of trained nurses in the daytime.
The researchers also found that during five of the seven weeks in which patients picked up MRSA, the ward's cleanliness standard was defined as below average.
They concluded that patients were seven times more likely to acquire MRSA infection during busy periods when there was a shortage of specially trained nurses.
Dr Stephanie Dancer, a consultant microbiologist from Scotland, who conducted the study, said the results came as a surprise.
"I have studied the acquisition of MRSA for several years now, and have previously focused on levels of hygiene.
"These results show that MRSA acquisition is caused by the culmination of a number of different factors.
"In this study, understaffing was a significant factor, exacerbated by poor ward hygiene and further studies are required to explore this in more detail.
"It is assumed that when nurses are particularly busy due to understaffing, they do not have time to wash their hands."
Dr Anna Batchelor, president of the Intensive Care Society, said understaffing was a particular problem in many intensive care units.
"This study highlights how a lack of trained staff puts patient lives in danger.
"The challenge for intensive care is now to ensure more nurses are brought into the speciality and that the new Government commits to adequate funding for trained staff," she said.