Aseptic Technique is a Process
According to the section on SURGERY-Aseptic Technique in The Guide for the Care and Use of Laboratory Animals, 8th Edition, aseptic technique is used to reduce microbial contamination to the lowest possible practical level (Mangram et al. 1999). No procedure, piece of equipment, or germicide alone can achieve that objective (Schonholtz 1976): aseptic technique requires the input and cooperation of everyone who enters the surgery area (Belkin 1992; McWilliams 1976). The contribution and importance of each practice varies with the procedure. Regardless of the species, aseptic technique includes preparation of the patient, such as hair or feather removal and disinfection of the operative site (Hofmann 1979); preparation of the surgeon, such as the provision of appropriate surgical attire, face masks, and sterile surgical gloves (Chamberlain and Houang 1984; Pereira et al. 1990; Schonholtz 1976); sterilization of instruments, supplies, and implanted materials (Bernal et al. 2009; Kagan 1992b); and the use of operative techniques to reduce the likelihood of infection (Ayliffe 1991; Kagan 1992a; Lovaglio and Lawson 1995; Ritter and Marmion 1987; Schofield 1994; Whyte 1988).
While the species of animal may influence the manner in which principles of aseptic technique are achieved (Brown 1994; Cunliffe-Beamer 1983; Gentry and French 1994), inadequate or improper technique may lead to subclinical infections that can cause adverse physiologic and behavioral responses (Beamer 1972; Bradfield et al. 1992; Cunliffe-Beamer 1990; Waynforth 1980, 1987) affecting surgical success, animal well-being, and research results (Cooper et al. 2000). General principles of aseptic technique should be followed for all survival surgical procedures (ACLAM 2001).
Specific sterilization methods should be selected on the basis of the physical characteristics of the materials to be sterilized (Callahan et al. 1995; Schofield 1994) and sterilization indicators should be used to validate that materials have been properly sterilized (Berg 1993). Autoclaving and plasma and gas sterilization are effective methods most commonly used to sterilize instruments and materials. Alternative methods, used primarily for rodent surgery, include liquid chemical sterilants and dry heat sterilization. Liquid chemical sterilants should be used with appropriate contact times and instruments should be rinsed with sterile water or saline before use. Bead or dry heat sterilizers are an effective and convenient means of rapidly sterilizing the working surfaces of surgical instruments but care should be taken to ensure that the instrument surfaces have cooled sufficiently before touching animal tissues to minimize the risk of burns. Alcohol is neither a sterilant nor a high-level disinfectant (Rutala 1990) but may be acceptable for some procedures if prolonged contact times are used (Huerkamp 2002).
Misconceptions regarding Aseptic Technique
Rodents are virtually impervious to post-operative wound infection
FALSE: It is a common misconception that rodents do not become infected during non-sterile surgery or other invasive procedures, such as the placement of indwelling catheters, however, rodents are susceptible to infections during surgery and they can impact research outcomes (Bradfield et.al., 1992; Hoogenstraten-Miller and Brown, 2008; Huerkemp, 2002). In fact, the rat is a commonly used research model for investigating the pathophysiology of sepsis (Zannotti-Cavazzoni and Goldfarb, 2009).
If an animal has an infection, I would see pus
FALSE: Surgical wounds can have a significant number of bacteria present without the visible presence of pus.
I can autoclave exam gloves to use for surgical procedures instead of surgical gloves to save money
FALSE: All types of examination gloves are very thin and must not be reprocessed for reuse (Korniewicz et.al, 1990). The exam gloves do not dry well after being autoclaved. Wet=contaminated
Sutures, staples, or wound clips do not have to be removed 10-14 days after surgery.
FALSE: Wound closures left in too long increase the risk of infection because suture acts as a wick for microbes and can make extraction more painful.
I do not have to remove hair from the surgical site as long as I scrub the area well.
FALSE: Hair must be removed to prevent infection. A suitable size surgical field has been created when the long hairs at the edge are unable to contact the incision, and the hairs at the edge will not be included when the wound is closed. It is inappropriate and unacceptable surgical technique to have long hairs from the margin included in the closed incision.
I can reuse the same set of surgical instruments on multiple animals.
TRUE & FALSE:
TRUE- for rodents, the same set of instruments can be used on a maximum of 5 animals if you are cleaning the instruments between cases and disinfecting the instruments with 70% isopropyl alcohol or preferably using a hot bead sterilizer.
FALSE-for USDA-regulated animals, you must use a new sterile pack for each animal.
I can use the same suture material from the same pack on multiple animals.
TRUE & FALSE:
TRUE- for rodents, you can use the same suture material from the same pack on a maximum of 5 animals.
FALSE- for USDA-regulated animals, you must use a new sterile suture pack for each animal.
References:
- American College of Laboratory Animal Medicine Position on Rodent Surgery. http://www.aclam.org/education-and-training/position-statements-and reports
- Bradfield, J.F., Schachtman, T.R., McLaughlin, R.M., & Steffen, E.K. Behavioral and Physiologic Effects of Inapparent Wound Infection in Rats. Lab Animal Science 42, 572-578 (1992).
- Hoogstraten-Miller, S.L. & Brown, P.A. Techniques in Aseptic Rodent Surgery. Current Protocols in Immunology, Unit-1.12-14 (2008).
- Huerkamp, M.J. Alcohol as a Disinfectant for Aseptic Surgery of Rodents: Crossing the Thin Blue Line? Contemp Top Lab Anim Sci. 41, 10-12 (2002).
- Zanotti-Cavazzoni, S.L. & Goldfarb, R.D. Animal Models of Sepsis. Critical Care Clinics 25, 703-719 (2009).