WASHINGTON (Reuters) - Overcrowded hospitals that try to cope with growing patient loads by churning them through more quickly may be helping the spread of drug-resistant germs, Australian researchers reported on Monday.

As populations grow, and as people live longer lives, this problem will only worsen, Dr. Michael Whitby of Princess Alexandra Hospital in Brisbane and colleagues reported.

"The drive towards greater efficiency by reducing the number of hospital beds and increasing patient throughput has led to highly stressed health-care systems with unwelcome side-effects," they wrote in the Lancet Infectious Diseases.

Hospitals filled to capacity are more likely to have outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) and other infections, they said in a review of several studies on the issue.

Many studies have shown that doctors, nurses and other health care workers do not wash their hands as well and as frequently as recommended, and this problem worsens during times of understaffing and high workload, they said.

Overcrowded hospitals also struggle to isolate patients with MRSA and other dangerous infections.

The study noted for example that in Australia, the number of public hospital beds per person fell by 40 percent between 1982 and 2000, while 14 percent more patients were treated.

Other developed countries such as Britain, the United States and Canada have similar trends, they said. Hospitals often cope by treating patients in a single day instead of admitting them as inpatients.

"Workforce ageing is also a problem — in the United States, average-age of nurses has increased from 37.4 years in 1983 to 46.8 years in 2004," they wrote.

MRSA killed an estimated 19,000 Americans in 2005 and made 94,000 seriously ill, according to one report last October in the Journal of the American Medical Association.

MRSA infections can range from boils to more severe infections of the bloodstream, lungs and surgical sites. It is spread by the hands and on contaminated medical equipment.

The Association for Professionals in Infection Control and Epidemiology reported last year that nearly five percent of US patients were infected or colonised with MRSA.