Infection control 101 (Proceedings)

Veterinarians must take appropriate precautions to mitigate the risk of infectious disease in patients and hospital personnel.  Veterinary hospitals are continually faced with the potential introduction of infectious diseases into the hospital environment.  In a survey of infection control programs at Veterinary Teaching Hospitals (VTHs), 82% reported outbreaks of healthcare-associated infections (HCAIs) in the previous 5 years with 58% restricting patient admissions and 32% closing part of the facility to aid in mitigation efforts [1].  Further, 50% also recognized zoonotic infections in personnel.  In order to provide excellent patient care, veterinary practices must implement an infection control program to protect the personnel, the patients, and the hospital.  Not only is there an ethical responsibility to consider infection control in daily practice, but there is a recognizable standard of care with respect to infection control [2].  The veterinarian not only has a clear duty to recommend preventive measures to reduce the risk of zoonotic disease and to counsel clients to seek medical attention in the event of zoonotic disease exposure, but veterinarians are key partners in the promotion of public health – having both the knowledge base and practical experience to identify potential risks and employ both epidemiologically and scientifically sound prevention strategies [3].

The Study on the Efficacy of Nosocomial Infection Control (SENIC), conducted in U.S. human healthcare facilities from 1970-1976, found that an effective infection control program can have a significant impact on HCAI  rates – estimating a 32% reduction in overall rates [4].  This study specifically identified employing trained infection control personnel, conducting surveillance activity, and having a system for reporting back to stakeholders as key components in a comprehensive program.  Currently, equivalent data is lacking in veterinary medicine, however, it is not unreasonable to assume a similar reduction in veterinary hospitals implementing similar infection control programs.

Every veterinary facility is unique with its own physical and operational limits – each having specific infection control program components tailored to the needs of each facility.  While each program will be unique with respect to its finer details, they will be based on foundational infection control principles.  There are general systematic approaches, such as the Hazard Analysis and Critical Control Point (HACCP) system, which can aid in policy and program development [5].  The first step in any control effort should be the identification of risks and hazards specific to the facility.  Consider pathogens which are zoonotic, foreign to the region, agents with a high nosocomial transmission risk, and those likely to have a major impact on patient management and welfare.  Second, identify critical control points (CCP) or points at which a hazard can be prevented or minimized by applying a control measure.  Consider physical areas or processes where the transmission of pathogens is likely to occur.  Critical control point monitoring is essential to determine when a critical limit has been exceeded triggering a corrective or preventive action. The level and type of monitoring will be specific to each facility and depend upon stakeholder level of risk aversion and the available resources, both financial and personnel.  It is important to note that conducting active surveillance for an organism which survives relatively well in the environment not only can help identify important pathogen reservoirs, but can also indicate overall protocol compliance and effectiveness.  Establishing a corrective action plan in response to recognized problems is central to an effective biosecurity program; allowing for an efficient and effective response. 

There are many simple practices that can aid in the prevention of disease transmission such as decreasing contact by implementing barrier nursing precautions, creating separation and isolation, or even employing hospital closure during times of epidemic disease.  This decision in part will be based on the infectious agent of concern, the hospital population, and the intended purpose for the precaution or action.  Barrier nursing is intended to create a barrier between “clean” and “contaminated.”  Separation creates hospital areas with differing levels of biosecurity.  These areas may be related to species (e.g., small animal vs. large animal or equine vs. bovine), to the type of animal (e.g., adult vs. foal), to the disease severity (e.g., colic, systemic disease, or elective surgery), or to the type of patient (e.g., inpatient vs. outpatient).  Isolation is typically reserved for confirmed cases of infectious disease or those considered at highest risk and hospital closure is generally thought of as a means of outbreak containment within an affected facility – but can also be a measure to prevent disease introduction at times of widespread outbreaks in a given geographic location. 

Reducing the environmental load of potential pathogens is critical in an environment where animals from many different herds in varying states of immune compromise are comingled.  A recent report of epidemic salmonellosis in a VTH sighted ineffective cleaning and disinfection as an important factor in the outbreak which resulted in patient fatalities, hospital closure, and an estimated financial cost of US$4.1 million [6].  Proper use of cleaning and disinfection is key in eliminating sources of infectious agents and breaking the cycle of transmission.  While rigorous cleaning alone can reduce the bacterial load on a concrete surface by 90%, applying a disinfectant after cleaning can reduce this by an additional 6% [7]. 

Cleaning and disinfection efficacy should be routinely monitored to ensure the ICP is effective in an ever changing landscape.  There are many methods for accomplishing this including surveillance for syndromes commonly associated with HCAIs or routine environmental monitoring using electrostatic wipes or sterile sponges to culture specific organisms of concern, or contact plates (i.e., Rodac plates) to enumerate non-specific bacterial growth [8-12].  Incorporating environmental surveillance into an ICP requires consideration of sample type, sample collection and detection method, selection of a diagnostic laboratory, and available resources (both financial and personnel); as well methods should be appropriately validated and optimized for their intended use.  To gain meaningful information, environmental testing should be performed regularly to establish a baseline level of contamination to which future findings can be compared.  In this way potential environmental reservoirs of microorganisms can be detected and cleaning effectiveness can be continually monitored.       

Routine cleaning and disinfection helps to minimize the burden of bacteria in the environment that may serve as a source for HCAIs.  While all housing areas should be cleaned and disinfected between patients, special attention should be paid to areas known to have housed patients with suspected infectious diseases and tended to immediately after use to minimize inadvertent trafficking of pathogens from contaminated to clean areas.  Equipment in contact with animals suspected or confirmed of having an infectious disease should be cleaned and disinfected before reuse and handled in a manner to prevent contamination of hospital surfaces.  Keep in mind that for equipment contacting mucous membranes (e.g., endotracheal tube, nasogastric tube) disinfection should be attained via dry/moist heat sterilization or application of an antiseptic (a product approved for use on living tissue).  It is critical that cleanable surfaces be maintained throughout veterinary hospitals.  Dirt floors or porous surfaces (e.g., untreated wood) cannot be effectively disinfected and therefore should be avoided.  If porous surfaces are present, they can be rendered less so by painting or sealing the surface – which may need to be done routinely throughout the lifetime of the facility.

Animals in the general population are typically considered to be healthy.  As such, the focus of an infection control program for a premise may be weighted more heavily toward preventing the entry of an infectious agent onto the premises through traveling horses, non-resident horses, or visiting personnel (i.e. veterinarian, farrier).  In general, premise biosecurity program development should consider five key areas:  animals, people, environment, access, and movement.  As previously stated, designing a program can be facilitated by using a systematic approach, such as HACCP, to evaluate risks, implement control points, and program monitoring [5].  The adoption of biosecurity practices on an animal operation is a balance of perceived benefit versus the impact of implementation. The benefits of a biosecurity program can be hard to realize as it is difficult to measure the cost of an outbreak averted. 

Practice managers must keep in mind that an infection control program is dynamic in nature and should be pliable enough to accommodate many different situations – evolving with the facility, its patient population, its staffing situation, and the changing risk of infectious disease.  Infection control procedures should be rigorous, but not to the detriment of patient care.  As veterinarians, it is our obligation and responsibility to become educated and aware of the risks posed to personnel, patients, and the hospital in the daily practice of veterinary medicine.

References

Benedict, K.M., Morley, P.S. and Van Metre, D.C. (2008) Characteristics of biosecurity and infection control programs at veterinary teaching hospitals. J Am Vet Med Assoc 233, 767-773.

Morley, P., Anderson, M. and Burgess, B. (2012) Report of the third Havemeyer workshop on infection control in equine populations. Equine Vet J.

Babcock, S., Marsh, A.E., Lin, J. and Scott, J. (2008) Legal implications of zoonoses for clinical veterinarians. J Am Vet Med Assoc 233, 1556-1562.

Haley, R.W., Culver, D.H., White, J.W., Morgan, W.M., Emori, T.G., Munn, V.P. and Hooton, T.M. (1985) The efficacy of infection surveillance and control programs in preventing nosocomial infections in US hospitals. Am J Epidemiol 121, 182-205.

Morley, P.S. (2002) Biosecurity of veterinary practices. Vet Clin North Am Food Anim Pract 18, 133-155, vii.

Dallap Schaer, B.L., Aceto, H. and Rankin, S.C. (2010) Outbreak of salmonellosis caused by Salmonella enterica serovar Newport MDR-AmpC in a large animal veterinary teaching hospital. J Vet Intern Med 24, 1138-1146.

Dwyer, R.M. (2004) Environmental disinfection to control equine infectious diseases. Vet Clin North Am Equine Pract 20, 531-542.

Burgess, B.A., Morley, P.S. and Hyatt, D.R. (2004) Environmental surveillance for Salmonella enterica in a veterinary teaching hospital. J Am Vet Med Assoc 225, 1344-1348.

Ruple-Czerniak, A., Aceto, H.W., Bender, J.B., Paradis, M.R., Shaw, S.P., Van Metre, D.C., Weese, J.S., Wilson, D.A., Wilson, J.H. and Morley, P.S. (2013) Using syndromic surveillance to estimate baseline rates for healthcare-associated infections in critical care units of small animal referral hospitals. J Vet Intern Med 27, 1392-1399.

Ruple-Czerniak, A., Bolte, D.S., Burgess, B.A. and Morley, P.S. (2013) Comparison of two sampling and culture systems for detection of Salmonella enterica in the environment of a large animal hospital. Equine Vet J.

Ruple-Czerniak, A.A., Aceto, H.W., Bender, J.B., Paradis, M.R., Shaw, S.P., Van Metre, D.C., Weese, J.S., Wilson, D.A., Wilson, J. and Morley, P.S. (2013) Syndromic surveillance for evaluating the occurrence of healthcare-associated infections in equine hospitals. Equine Vet J.

Stockton, K.A., Morley, P.S., Hyatt, D.R., Burgess, B.A., Patterson, G., Dunowska, M. and Lee, D.E. (2006) Evaluation of the effects of footwear hygiene protocols on nonspecific bacterial contamination of floor surfaces in an equine hospital. J Am Vet Med Assoc 228, 1068-1073.