Aerosolized microbes may pose contamination hazard in OR.(Gynecology)(operating room)

TUCSON, ARIZ. -- Nasopharyngeal shedding of aerosolized microbes may be a vector for perioperative contamination in the operating room, Charles E. Edmiston Jr., Ph.D., reported at the annual meeting of the Central Surgical Association.

Barriers to contamination, such as surgical masks, may not adequately contain microbial aerosols, especially when they are worn for long durations, added Dr. Edmiston of the Medical College of Wisconsin, Milwaukee.

"Ten to fifteen years ago we would have never talked about this, because you primarily looked upon infections that occurred during the perioperative or even postoperative period as being mediated merely by contact," he said.

Over an 18-month period, Dr. Edmiston and his collaborators matched cultures obtained from air in the operating room with nasal cultures taken from an 11-member vascular surgery team during 70 vascular reconstruction procedures. An air-sampling device used a 0.45-[micro]m filter to collect the air at four points located within 0.5-1 m or 4-5.5 m from the surgical wound.

The investigators recovered strains of coagulase-negative staphylococci, such as Staphylococcus aureus, during 60 (86%) of the 70 procedures; these strains were collected 0.5-1 m away from the wound in 36 of the procedures. Another third of the isolates were S. epidermis.

Gram-negative bacteria grew in cultures after the perioperative sampling period in 23 (33%) of the 70 procedures. Three of the isolates--Stenotrophomonas maltophilia, Burkholderia cepacia, and Aeromonas species--entered the operating room as an aerosol when surgical team members turned on the faucet of a utility sink. Most of the recovered strains showed patterns of resistance to multiple drug groups, such as the amino-glycosides, [beta]-lactams, and fluoroquinolones.

In several selected cultures, Dr. Edmiston and his colleagues used pulsed-field gel electrophoresis, a tool commonly employed by molecular epidemiologists to investigate infectious disease outbreaks. They discovered that isolates derived from air samples were often from the same clonal family of isolates obtained from the nasal cultures of the surgical team.