Vet Times The website for the veterinary profession https://www.vettimes.co.uk MRSA CROSS INFECTION RISK: IS YOUR PRACTICE CLEAN ENOUGH? Author : CATHERINE F LE BARS Categories : Vets Date : February 25, 2008 CATHERINE F LE BARS discusses recommended guidelines for the control of MRSA infection within the practice STAPHYLOCOCCUS aureus is carried on the skin, or in the nose, by approximately 30 per cent of the population. It can either be part of the normal fl ora or cause disease. Methicillin-resistant Staphylococcus aureus(mrsa) is a variant of this organism that exhibits resistance to a variety of antibiotics. Although much media attention has focused on its role in hospital-acquired infections, it is now becoming recognised in veterinary medicine. This article will examine the measures that can be taken to control crossinfection within veterinary practices. Most of the information is drawn from the BSAVA, DEFRA and RVC websites. MRSA overview Methicillin came into use in 1959 to treat infections caused by penicillin-resistant S aureus. By 1961, reports were emerging of MRSA. Resistance to methicillin is conferred by the meca gene, which also confers resistance to all beta lactam antibiotics, including oxacillin, flucloxacillin and cephalosporins. Approximately 40 per cent of S aureus isolated in the UK are methicillin resistant. The bacterium generally resides in the external nares, axillae and perineum of carriers. Firm figures for the number of asymptomatic carriers in the general population vary considerably between countries and studies. However, some research suggests that 20 per cent of the population may be 1 / 13
permanently colonised, with up to 40 per cent of people acting as transient carriers. Healthcare workers and hospital patients have been identified as having the highest rates of colonisation. MRSA is now a significant problem in hospitals and nursing homes worldwide and recent evidence suggests the appearance of community acquired infect ions. Official figures show that UK hospitals have one of the highest incidences of MRSA. According to health care studies, 15 per cent of reported infections result in death, although in most people the condition is localised and treatable. In 1999, the first UK case in an animal was officially diagnosed at the RVC. Since that time MRSA has been isolated from a wide range of species, including dogs, cats, horses and rabbits. As in people, MRSA rarely poses a threat to healthy animals. Animals at greatest risk of succumbing to disease include the immunosuppressed and those recovering from major surgery. Implants and intravenous catheters are also associated with infection. A carrier may infect susceptible individuals or develop signs of disease themselves if they are subjected to surgery or illness. MRSA should be suspected whenever animals a re presented for non-healing wounds. These may be a result of injury or surgical procedures. Other diseases reported worldwide include: mastitis in cattle; abscesses and urinary tract infections in cats; pyoderma, arthritis, pneumonia and prostatitis in dogs; chronic sinusitis in parrots; ear infections in rabbits; and myositis in chickens. Control measures There are two main sources of MRSA to be found in veterinary practice: ie staff and animals that are already colonised with the bacteria. Both groups may contaminate the environment or infect atrisk animals directly. Once infected, these animals can also act as reservoirs and transmit the organism to other patients and humans. The Queen Mother Hospital at the RVC in Hertfordshire recognised the presence of MRSA as early as 1997. Since that time, it has been responsible for many of the publications regarding the subject in British veterinary literature. At present it sees at least one case a month and has stringent measures in place for handling these cases and preventing spread to both its staff and other patients. Its strategy focuses on identifying at-risk patients and carriers. All animals considered high risk for the disease for example, those owned by healthcare workers are swabbed shortly after admission and barrier nursed until the results are known. If found to be positive for MRSA they are then moved to an isolation ward. 2 / 13
The BSAVA has issued a set of guidelines for veterinary practices to prevent the establishment and dissemination of MRSA. The four key points are: scrupulous hand hygiene; a clean environment; prudent antibiotic use; and compliance with all the above. Routine measures to prevent MRSA spread It is important that methods used for hand decontamination and environmental disinfectants are effective against MRSA. Easy access to antibacterial gels or hand rubs encourages hygiene and can be used before and after handling an animal, and before touching equipment, such as pens and keyboards. Where hands are soiled, then soap and water must be used. Consider using waterproof keyboards, fl at keyboards or keyboard covers. It is recommended that practices provide simple uniforms that can be laundered on site. Gloves and disposable aprons should be worn when making direct contact with patients, body fluids, lesions and other contaminated materials. These must be changed between patients. Face and eye protection should also be worn if aerosols are likely to be generated. Existing wounds or skin lesions should be covered with waterproof dressings and staff members should avoid invasive procedures if suffering from skin lesions on hands. Patients with, or suspected of having, MRSA should be placed in isolation. The guidelines encourage the rational use of antibiotics to minimise the development and spread of antibiotic resistance and high standards of aseptic technique for all invasive procedures. These include: minimising theatre staff to necessary personnel only; use of sterile gowns, gloves, hats and masks; proper sterilisation of equipment and restricting use to a single patient; employing single-use disposable equipment where appropriate; effective disposal of contaminated material; and, as stated above, hand hygiene and disinfection of surfaces between patients. High standards of ward cleaning are imperative. Cages should be cleaned at least once daily, and disinfected thoroughly between patients. Soiled bedding must be disposed of or cleaned and disinfected as soon as possible. There must be no contact with clean bedding or other animals. All waste should be disposed of, according to its nature, in appropriate containers and by appropriate means. This applies to clinical waste, sharps and general kennel waste. Ensure that all staff members are aware of, understand and adhere to infection control guidance. 3 / 13
Designating specific staff to monitor and enforce infectious disease control measures, and undertake infection control audits would be advisable. Managing patients A DEFRA/BSAVA working party is establishing guidelines for the sampling, isolation and identification of MRSA. It is thought that the clinical risk associated with asymptomatic carriers is low, and that routine screening of all animals prior to admission is neither feasible or necessary. However, screening should be considered in pets from households with MRSA or belonging to: healthcare workers; patients with nonhealing wounds; patients with infections not responding to antibiotics, especially where culture and sensitivity has indicated the presence of staphylococci; practice-acquired or secondary infections in at-risk patients; practices where MRSA is endemic or transmission is suspected; and animals dying of sepsis or other invasive infections. Samples for culture should be submitted to a laboratory with the facility to identify MRSA as soon as possible. All samples should be packaged securely with an external form stating clearly that MRSA is suspected. Note that laboratories now routinely test for resistance to oxacillin, as methicillin is no longer produced. If MRSA is suspected or confirmed, the infected patient should be isolated, and contact with staff and other animals kept to a minimum. Procedures involving the patient should be scheduled towards the end of the day where possible and any potentially contaminated rooms or equipment disinfected thoroughly prior to further use. It is important that staff members with major skin defects, such as eczema or psoriasis, or who are immunosuppressed, do not have contact with infected animals. Standard barrier nursing should be employed, using appropriate protective clothing. Equipment such as pens, thermometers and stethoscopes should be reserved for use with that patient only and disposed of or disinfected after use. Bedding may be disposed of or laundered at 60ºC. The cage and immediate environment should be disinfected daily, and body fluids cleaned away immediately. Bathing the animal every two to three days may reduce cutaneous and mucosal carriage, but this must be balanced against the practicality and risk of increasing staff contact with the animal. Prior to surgery, antibacterial baths and intranasal medicants, such as chlorhexidine, neomycin or mupirocin, may reduce the risk of postoperative colonisation. Owners may visit their pets; however, they must be advised of the potential risks. Contact with the animal should be kept to a minimum and owners should wear protective clothing and wash their hands thoroughly. 4 / 13
The decision on whether to treat carrier patients depends on the individual case. Most UK veterinary isolates are sensitive to routine antibiotics, such as potentiated sulfonamides, tetracyclines and fusidic acid. MRSA-positive patients should be cultured prior to discharge and sent home as soon as they are clinically fit. Potential risks and recommended precautions must be discussed and the owner asked to sign an acknowledgement prior to discharge. If an MRSA-positive animal dies, the body should be placed in a sealed, impervious bag and be disposed of by cremation. Animals with persistent mucosal colonisation can be treated with an antibacterial shampoo and intra-nasal antibacterials two to three times daily. Decolonisation should only be undertaken where necessary for example, if there is an immunosuppressed or otherwise vulnerable owner with the full consultation and cooperation of medical healthcare services. Some animals that become persistent carriers during hospitalisation will be undetected. Predischarge screening, however, is only a measure of the colonisation rate in the practice and it is uncertain whether this is of much clinical importance in healthy individuals. Screening staff and practice premises When screening staff for MRSA it is important to distinguish between transient carriage and permanent colonisation. The latter is very common and accounts for the majority of cross infection. It can be controlled by good hygiene especially hand washing. As a rule, the screening of staff is not recommended when they have just been at work, but rather when they have had no recent contact with potential carrier animals. Any staff in contact with confirmed cases should examine themselves for skin lesions and report these. Routine screening should be undertaken if multiple infections occur within a practice or if control measures do not appear to be preventing staff-to-animal transmission. Resident practice animals should also be screened. The issues of consent and confidentiality, as well as further action, must be carefully addressed. Staff members who have been identified as permanent carriers should be encouraged to visit their own GP. However, treatment is not always recommended due to the issues of antibiotic resistance, the fact that re-colonisation is common, and that transmission can be controlled just by good hygiene. The role of environment in continuing outbreaks is unclear and routine sampling is not advised. However, MRSA can survive for up to 12 months in dust, bedding and clothing and it has been proven that MRSA rates decline in hospitals employing cleaners trained in microbiological cleanliness. Hand-touch sites, such as door handles, computer keyboards and mice, taps and 5 / 13
clinical equipment, should be cleaned regularly; however, one study demonstrated that only 30-45 per cent of most visibly clean surfaces were not microbiologically clean. Although it is not practical to close contaminated premises, the area should be cleaned and disinfected thoroughly before further use. Conclusion MRSA is one of the most prevalent organisms associated with nosocomial infections worldwide and there is increasing evidence to suggest that it is a significant, albeit as yet uncommon, problem in veterinary practice. The evidence available suggests that humans are the likely source of bacteria infecting or colonising animals. These animals may, in turn, act as reservoirs and transmit the bacteria to other animals or humans. Although MRSA rarely causes disease in healthy individuals, it presents a significant risk to debilitated or immunosuppressed patients. Strict adherence to personal hygiene is the most effective means of keeping the risk of MRSA within a practice to a minimum. Guidelines for veterinary practices from the BSAVA and Defra can be found on their respective websites at www.bsava.com and www.defra.gov.uk References are available on request to the editor. 6 / 13
Inset. Hand touch sites such as door handles, computer keyboards and mice, taps and clinical equipment should be cleaned regularly. 7 / 13
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Below. MRSA can survive for up to 12 months in dust, bedding and clothing. It has been proven that MRSA rates decline in hospitals employing cleaners trained in microbiological cleanliness. 9 / 13
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Left. Antibacterial gels or hand rubs attached to uniforms and kennel doors are a visual cue for cleanliness. 11 / 13
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Below. Screening for MRSA should be considered in patients with non-healing wounds. 13 / 13 Powered by TCPDF (www.tcpdf.org)