A new US study suggests that post-surgery infection by the bacterium Staphylococcus aureus (Staph), a type commonly acquired in hospital settings, is more likely to occur after operations to the chest and head than other major procedures.

The retrospective cohort study is available to read online and is due to appear in the July print issue of the journal Infection Control and Hospital Epidemiology.

Lead author Dr Deverick Anderson, an infectious diseases specialist at Duke University Medical Center in Durham, North Carolina, told the media that:

"We found that chest and head procedures accounted for the majority of staph infections after major surgery."

Anderson and colleagues analyzed data on 96,455 orthopaedic, neurosurgical, cardiothoracic, and plastic surgery procedures performed between 2003 and 2006 on 81,267 patients at 11 centers (9 community hospitals and 2 tertiary care hospitals in North Carolina and Virginia).

They found that:
  • 454 patients had S. aureus infections: 317 had surgical site infection, 188 had bloodstream infection, and 51 had both.

  • The overall incidence of infection was 0.47 per 100 procedures.

  • Around half of infections (51 per cent) were due to methicillin-resistant S. aureus (MRSA).

  • S. aureus infection was more common after cardiothoracic procedures (0.79 infections per 100 procedures) than after orthopedic, neurosurgical or plastic surgical procedures (0.37, 0.62 and 0.32 per 100 respectively).

  • The highest rate of bloodstream infection was after cardiothoracic procedures ( 0.57 infections per 100 procedures), comprising almost 75 per cent of infections.

  • The highest rate of surgical site infection was after neurosurgical procedures (0.50 infections per 100 procedures), comprising 80 per cent of infections.
The authors concluded that:

"The frequency and type of postoperative invasive S. aureus infection varied significantly across procedure types."

They recommended that the "highest risk procedures, such as cardiothoracic procedures, should be targeted for ongoing preventative interventions".

Anderson, who also works with the Duke Infection Control Outreach Network (DICON), said a key message of the study was that "one prevention strategy does not fit all" and there may be a need to have strategies for cardiovascular and neurosurgical procedures that are not necessary for plastic or orthopaedic surgery.

He also said strategies that focus exclusively on MRSA will not necessarily prevent all infections:

"On average MRSA was only present in half of the infections that we identified," he added.

The study was funded by Merck & Co, and two of its authors work at their labs in North Wales, Pennsylvania, but according to a statement they were not involved in the analysis of the data.

"Variation in the Type and Frequency of Postoperative Invasive Staphylococcus aureus Infections According to Type of Surgical Procedure."
Deverick J. Anderson, Jean Marie Arduino, Shelby D. Reed, Daniel J. Sexton, Keith S. Kaye, Chelsea A. Grussemeyer, Senaka A. Peter, Chantelle Hardy, Yong Il Choi, Joelle Y. Friedman, Vance G. Fowler, Jr.
Infection Control and Hospital Epidemiology Vol 31, No 7, 701-709, July 2010
DOI: 10.1086/653205

Source: Duke Medicine.

Written by: Catharine Paddock, PhD