Disinfection of Environments Contaminated by Staphylococcal Pathogens

Chapter 107

Disinfection of Environments Contaminated by Staphylococcal Pathogens

Environmental contamination with pathogens commonly occurs in veterinary hospitals. Rooms in which dermatologic patients are examined are considered high-risk areas because patients frequently have infected lesions or open wounds, are immunocompromised, or are receiving antimicrobial treatment. Of particular concern are methicillin-resistant Staphylococcus pseudintermedius (MRSP) and methicillin-resistant Staphylococcus aureus (MRSA) because they cause health care–associated and nosocomial infections in dogs and cats, and MRSA is an important occupational health risk for veterinary personnel. Studies have documented transmission of such pathogenic organisms through contact with contaminated surfaces. Therefore, in locations frequented by patients with dermatologic disease, intensive and detailed cleaning and disinfection protocols are critical to prevent potential transmission to humans and other patients. The purpose of this chapter is to summarize the human and animal contact surfaces most commonly contaminated with S. pseudintermedius and S. aureus in dermatologic areas and provide recommendations on how to clean and disinfect them to decrease the risk of transmission.


S. pseudintermedius is an opportunistic pathogen that is part of the normal flora of dogs and cats whereas S. aureus is not, although dogs and cats can acquire this pathogen from humans (see Chapter 100). Both S. pseudintermedius and S. aureus frequently are methicillin resistant; however, MRSP and MRSA strains are not more resistant to detergents or disinfectants, nor do they survive longer on contaminated surfaces than methicillin-susceptible strains.

Surfaces Commonly Contaminated by Staphylococci

Contaminated surfaces are important sources of hand exposure to pathogens for veterinary personnel, increasing the chances that they may become infected themselves or transfer the infection to other patients. During 5 years of active monthly surveillance at the Ohio State University Veterinary Medical Center (Hoet et al, 2011), over 90% of all MRSP and MRSA strains in the dermatology service areas came from 10 major surfaces (Table 107-1). Similar surfaces have been reported in other studies to be “hot spots” of environmental contamination in veterinary hospitals (Heller et al, 2009; Weese et al, 2004). In addition to focusing on surfaces listed in the table, it is recommended that a staff member observe animal and human flow through the veterinary clinic to identify additional hot spots in the facility.

Selection and Proper Use of Disinfectants for Specific Surfaces

Antimicrobial-resistant pathogens can persist on environmental surfaces for weeks or months if regular cleaning and disinfection are not performed. In our active surveillance, we have detected the same clone of staphylococcus at the same location for as long as 5 months when cleaning and disinfection protocols were not properly followed. Surfaces such as computer keyboards, drawer handles, and paper towel and alcohol gel dispensers frequently are touched by veterinary personnel and often are cleaned and disinfected inadequately. Some surfaces are very difficult to disinfect, such as leather or nylon muzzles, which may be persistently contaminated.

To avoid long-term contamination and decrease potential sources of exposure, our recommendations are the following.

Gurneys, Examination Tables, and General Surfaces

Use of quaternary ammonium–based disinfectants (quats), which have detergent (cationic) properties and are active against most bacteria, is efficacious and cost effective. Chlorhexidine is a good alternative, but it does not confer any advantages over quats for the destruction of staphylococci, and some formulations are not labeled as active against other gram-positive cocci or Pseudomonas, also important dermatologic pathogens. Both disinfectants may be inactivated by the minerals found in hard water. Whether quats or chlorhexidine solutions are used, we recommend the following procedures:

• Remove all organic material (such as hair and dander) using paper towels.

• Wash surfaces that are soiled (e.g., with blood, pus, sebum) using water and soap or detergent, rinse per product label, and dry before applying the disinfectant. Organic material must be removed; otherwise, the effectiveness of disinfectants may be compromised.

• Anionic detergents (e.g., most laundry detergents) or soaps must be properly rinsed because they can inactivate these disinfectants, reducing their biocidal activity.

• Generously apply disinfectant, saturating the entire surface and allowing 10 minutes wet contact time for maximum effect (unless otherwise specified on the product label). Because this practice may be difficult to achieve during regular clinic activities, the solution should be left to dry before the next use. If there is suspected contamination with MRSP or MRSA, a full 10 minutes of wet contact time is essential. Note that rewetting with disinfectant may be necessary to achieve 10 minutes of wet contact time. Contact surfaces should be cleaned once daily at least.

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Jul 18, 2016 | Posted by in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off on Disinfection of Environments Contaminated by Staphylococcal Pathogens

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