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Helmet masks used in laminar, non-laminar flow operating room yield 80% bacterial contamination
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COPENHAGEN, Denmark — Research presented by British investigators at the 12th EFORT Congress 2011 indicated that orthopedic surgeons should change into a new pair of surgical gloves each time they touch the mask of their surgical helmets to avoid propagating infections during total joint surgery.
By touching their masks in the operating theater, surgeons “may transfer some of the bacteria from [their] visor mask to the operating field,” Vinay Kumar Singh, MBBS, D’ Orth, MRCS, MCh(Orth), Dip. SICOT, who presented his team’s findings, said.
During their study, Singh and colleagues identified coagulase negative Staphylococcus aureus and other aerobic and nonaerobic bacteria growing on surgical masks they tested after use in either laminar flow or non-laminar flow operating theaters.
“The laminar flow theater has a slightly less rate of contamination, and bacteria load is slightly less in comparison to the non-laminar flow theater,” he said.
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Swabbing procedure
For 40 total joint replacement surgeries conducted October 2009 to January 2010 — 20 each performed in a laminar flow theater (group 1) and a non-laminar flow theater (group 2) — a non-scrubbed team member wearing sterile gloves swabbed the surgical helmet visors of surgeons every 30 minutes until the end of the procedure, swabbing it six times from the top to the bottom and six times from side-to-side each time, Singh noted.
The swabs were immediately sent to the hospital’s microbiology laboratory where they were broken and placed in a cooked meat broth in a protocol selected by laboratory personnel.
“It was done in a sterile way so as to avoid any contamination,” after swabbing was complete, Singh said.
Laboratory testing, results
Any bacteria from the masks that were collected via the swabbing were grown in various media and incubated at controlled temperatures for set amounts of time. Investigators then quantified bacterial growth on a scale of 0 to 3, with no growth equal to 0 and heavy growth equal to 3. The Mann-Whitney U test was used to determine statistical significance.
Discussing the results, Singh said nine of 20 masks in group 2 were contaminated compared to none in group 1 shortly after the direct culture first swabs from the operating theater were tested. “Most of this contamination happened as soon as 30 minutes after the surgery,” he added.
“When the these swabs were incubated for 24 hours CO2 at 37° C and then tested again, about 70% of group 1 masks and about 90% of group 2 masks were contaminated. “If you combine both the theaters, around 80% of the masks did get contaminated,” Singh said.
In terms of numbers of isolates found, group 1 had 18 organisms and group 2 had 24 organisms, most of which were coagulase negative S. aureus. Streptococcus oralis and Streptococcus anginosus were also identified on laminar theater swabs. In addition to those isolates, diphtheroids, bacillus species, proteus species and Eshcerichia coli were found on non-laminar flow theater swabs.
Investigators found statistically significant contamination on masks between laminar and non-laminar theatere after direct incubation. However, after 24 hours of incubation, the mask contamination rates for both kinds of operating theaters were similar with no statistical difference. Therefore, Singh said, “We should avoid any inadvertent contact with them.” – by Susan M. Rapp
References:
- Singh VK, Hussain S, Javed S, et al. Sterile surgical helmet systems in elective hip and knee arthroplasty — Are they really sterile? Paper #1888. Presented at the 12th EFORT Congress 2011. June 1-4. Copenhagen, Denmark.
- Singh V, Kalairajah Y. Splash hazard in elective primary knee and hip arthroplasty — Are we adequately protected. J Bone Joint Surg Br. 2009; 94(8)B: 1074-1077.
- Vinay Kumar Singh, MBBS, D’ Orth, MRCS, MCh(Orth), Dip. SICOT, can be reached at Luton and Dunstable Hospital NHS Foundation Trust, Lewsey Road, Luton, LU4 0DZ United Kingdom; 44-7963636753; email: orthopaediks@gmail.com.
- Disclosure: Singh has no relevant financial disclosures.