21 January 2019

Disturbing bump in community-acquired staph cases

Aged Care Communicable Disease

The rate of life-threatening Staphylococcus aureus infections in Australia has been going up, but hospitals aren’t to blame.

An analysis of five years of data showed that the annual rate of community-acquired staph bloodstream infections went up by 8% in Victoria and 6% in Western Australia.

While more people were getting infected at home, hospitals appeared to be getting staph infection outbreaks under control.

A national surveillance program showed an overall decrease in the incidence of hospital-acquired disease.

While the incident rates of community-acquired staph in Victoria and Western Australia were still quite low, and were comparable to rates in other developed countries, the rate of increase was statistically significant.

S. aureus can be transmitted in the community through skin or soft-tissue infections. These can then develop into the more severe bloodstream infection, which have a mortality rate of around 20%.

The onset of the illness is rapid. Patients with community-acquired staph bloodstream infections usually present to emergency departments with acute symptoms.

The data in the study included presentations at around 150 hospitals, and excluded patients who had a catheter at home or who had recently undergone surgery.

So why is the prevalence of community-acquired staph on the rise?

“We don’t know exactly, but it’s probably due to one of two things,” Professor Leon Worth, a co-author on the study and an epidemiologist at the Victorian Healthcare Associated Infection Surveillance System Coordinating Centre in Melbourne, said.

“It may be that there are patients in the community that are more predisposed to infections. The second possible reason is that we are dealing with a bug that is more virulent, a bug that is more likely to cause invasive infections.”

The study found that the average age of patients contracting staph outside of hospitals was 60.

It could be that staph was becoming more common as the number of residents in aged-care facilities went up,  Professor Worth said.

The staph isolates in the study were highly-treatable with first-line antibiotic agents, such as flucloxacillin.

The message for general practitioners was get on to staph skin infections early, Professor Worth said.

MJA 2019, 21 January