Protecting patients and staff members from infection is fundamental to the operation of any surgical facility. Ambulatory and outpatient surgical centers tend to perform minimally invasive procedures; while these carry less inherent risk than more widely invasive procedures reserved for in-patient facilities, the potential for infection outbreaks remains very similar in both environments. Cost-effective infection prevention practices avert that potential by cutting links in the classic "chain of transmission" model: An infectious agent can be inactivated by sterilization or disinfection (antisepsis); a reservoir in which it grows can be modified or eliminated; its means of escaping the reservoir and transmission to a susceptible host curtailed by aseptic practices; and susceptibility of new hosts can be reduced by nutrition, immunization, and other health promotion measures.

In the surgical setting, two major reservoirs for infection outbreaks have been people and wet or complex equipment (especially endoscopes).¹ Surgeons,^{2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12} anesthetists,¹³ as well as both scrub and circulating nurses^{14, 15, 16, 17} and other surgical staff¹⁸ have been the source (reservoir) of infection by bacteria (notably Staphylococcus spp. and Streptococcus spp.), fungi (notably Candida spp.), and viruses (notably viral hepatitis). Contamination of medication solutions^{19, 20, 21, 22, 23} and contaminated endoscopes^{24, 25} have been at the root of several outbreaks by a variety of gram negative bacteria (notably Pseudomonas aeruginosa). Let's examine some prudent practices and controversies to prevent infection from these two sources.

Preventing outbreaks from human reservoirs
In the past several years, scientific investigation has debunked many practices once regarded as "common sense." Practices such as showering before changing into scrub clothing or wearing cover gowns when leaving protected operating room areas, for example, fell before evidence indicating that shedding rates increased after shower baths and cover gowns provided no real protection.^{26, 27} Similarly, restricting shoes²⁸ or wheeled stretchers²⁹ to an OR suite is just as ineffective. Advocated practices also change in response to changing fashion. Artificial nails have, for example, increased in popularity but also presented risk of infection.^{30, 31, 32} While an historic concern over nail polish proved finally pointless,³³ attention is now shifting to a ban on artificial nails.

A current controversy surrounds the recent suggestion that surgical masks also are not effective or necessary.^{34, 35} How good is the evidence, and are we asking the right question?

Can surgical masks be expected to reduce general infection rates?³⁶ The answer is probably no, for several reasons.

• First, consider the infectious dose (the number of microbes) required to initiate infection of a surgical site versus the number of organisms expelled from the mouth (and, to a lesser extent, the nose) when breathing, talking or coughing. Even when talking or coughing, numbers expelled are small relative to the number required to initiate infection (bear in mind, though, devitalized tissue and foreign bodies significantly reduces the infectious dose required).
• Second, consider the pathogens most frequently involved in surgical infections versus the nature of normal oral flora. It has long been recognized that other sources contribute more organisms to surgical wounds.
• Third, it also has long been recognized that surgical masks redirect microbes (due to leakage at the facial seal) despite claims of high filtration efficiency. Since mask material is clamped into a test frame in typical tunnel tests of filtration, resulting performance data used in sales claims is essentially meaningless for predicting effectiveness in practice. Because the studies reporting no difference in infection risk whether masks were worn or not fail to report the quality of mask usage as well as inherent risk and comparability of surgical procedures between groups, we cannot know whether any differences studied were between no mask use versus poor mask use, use or non-use in procedures where other sources of contamination contribute much larger bioloads, etc. In studies reporting the effect of masking on environmental contamination, position of sampling devices also appears to influence results.³⁷

A more pertinent question might be "Do surgical masks reduce the risk of infection outbreaks?" Group A beta-hemolytic streptococci are not normal flora but have a low infectious dose and have been found in surgical staff associated with outbreaks of infection in their patients. Sherertz et al., in investigating a Staphylococcus aureus outbreak, made the very interesting discovery that shedding rates were low from an implicated staff member who had nasal colonization until viral upper respiratory infection was present.³⁸ Past efforts at identifying S. aureus carriers concentrated on colonization alone and failed to explain variation in shedding rates. Outbreak investigations have described endophthalmitis following ocular surgery2 and meningitis following myelogram^{39, 40, 41, 42} associated with failure to wear a mask properly.

In summary, infection prevention practices should include:

• An effective surveillance system so that adverse trends can be recognized and investigated efficiently;
• Adequate staffing and support so that ill employees are encouraged to use sick leave when necessary;
• Effective antiseptic practices (including sterilization or disinfection of equipment as appropriate, preoperative site preparation that does not include unnecessary hair removal, and appropriate antimicrobial prophylaxis during surgery);
• Effective aseptic practices (including use of high-quality gowns, gloves and masks; minimizing traffic and conversation; controlling airflow quality, etc.)to reduce the risk of outbreaks from human reservoirs.

Practices to prevent outbreaks from supplies and devices
Complex products that are difficult to operate or clean have been the cause of numerous outbreaks. S. aureus, C. albicans, M. osloensis and hepatitis C infections have, for example, been associated with contamination of propofol containers used in anesthesia. Various microbes have been associated with outbreaks traced to contaminated endoscopes due to human failures, defects in automated decontamination systems, and (less-commonly) defective endoscopes.⁴³

The story behind a November 2001 voluntary recall of 15 Olympus bronchoscope models illustrates the importance of all these elements working in concert and consequences when they do not.⁴⁴ Infection rates two- to three-times higher than normal prompted investigation last December by the infection control department of a Maryland hospital, which subsequently learned that a Tennessee hospital had experienced similar problems that September. Initial investigations by the Maryland hospital were negative, and they reportedly were not advised of a recall notice when they first contacted the manufacturer. Apparently some recall notices were sent to "loading dock" addresses (likely because a purchasing department employee became registered as the user) rather than to departments actually using the devices or managing infection control and safety programs. The recall alert was broadcast through CDC's Rapid Notification Service (to subscribe or unsubscribe to RNS, go to www.cdc.gov/ncidod/hip and click on the RNS logo), and many recipients forwarded it along, but between lapses in circulation and wording of the notice itself (which placed emphasis on using proper cleaning procedures and a "loose" valve in an "urgent" yet voluntary announcement) more patients than necessary were exposed to risk.

In summary, infection prevention practices should include:

• An effective surveillance system so that adverse trends can be recognized and investigated efficiently;
• Attention to the biomedical literature and effective routing of recall or product warning notices so that hazard alerts are heeded;
• Effective monitoring of cleaning and decontamination procedures;
• Careful attention to manufacturers' instructions (especially regarding reuse, device compatibility issues, etc.) to reduce the risk of outbreaks from environmental reservoirs. n

REFERENCES CITED:
1) Garner JS, Dixon RE, Aber RC. Epidemic Infections in Surgical Patients. AORN J 1981;34(4):700-24
2) Allen HF, Mangiaracine AB. Bacterial Endophthalmitis after Cataract Extraction. ARCH OPHTHALMOL 1964;72:454-462.
3) Carl M, Blakey DL, Francis DP, et al. Interruption of Hepatitis B Transmission by Modification of a Gynaecologist's Surgical Technique. LANCET 1982;27Mar:731-3.
4) Goldmann DA, Breton SJ. Group C Streptococcal Surgical Wound Infections Transmitted by an Anorectal