Infection Control Today

DEC 2018

ICT delivers to infection preventionists & their colleagues in the operating room, sterile processing/central sterile, environmental services & materials management, timely & relevant news, trends & information impacting the profession & the industry

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Page 27 of 32

27 December 2018 ICT feature In healthcare facilities, the patient environment includes patient-care equipment and environmental surfaces and is well established as contaminated with pathogens that can cause infection. Patients with active infections with antibiotic-resistant organisms, coughs, purulent wounds, diarrhea, or vomiting are recognized as a source of pathogens and the use of transmission-based precautions (as recommended by the CDC) is central to preventing dissemination of pathogens that can ultimately result in an infection for other patients. Colonized patients also represent a risk of pathogen dissemination but since the rate of is generally believed to be lower for colonized patients than infected patients, most of the attention in preventing pathogen dissemination is related to infected patients. However, since the number of colonized patients and the rate at which they disseminate pathogens into the environment is generally less well understood, the overall burden may be much more signifi cant than is currently recognized. Consistent and correct use of standard and transmission-based precautions is generally relied on to protect healthcare workers and help control pathogen cross transmission for colonized (i.e., asymptomatic) patients. However, it is far from clear that the typical compliance levels with hand hygiene, environ- mental surface cleaning and use of barriers are adequate to manage this risk. As a result, interest has grown to better understand the role of colonized patients. Where do potential pathogens come from in colonized hosts? Colonization is referred to as the presence of microorganisms in or on a host, with growth and multiplication but without tissue invasion or cellular injury (PHAC 2013). A colonized person shows no obvious signs of disease yet can spread microorganisms into the environment through normal day-to-day activities. While most of the microorganisms shed are non-pathogenic to the colonized host, there may be bacteria that is pathogenic to other people, depending on the portal of entry or the immune system strength of the susceptible host. The potential for pathogen dissemination from an asymptomatic person is high as the average human body contains ~0.3 percent bacteria by weight (or about half a pound for the average person) (Sender, 2016). Three common sources of bacteria shed by people include, feces, saliva and skin cells. • Feces: Kelly (1994) notes that the colon contains more than 500 species of bacteria and that healthy feces may contain more than 1x1012 colony forming units (CFU)/gram of feces. Sender more recently estimated that the intestines may contain from 1x108 to 1x1011 bacteria per milliliter. One study (Stephen, 1980) demonstrated that bacteria were 54.7 percent of the total mass of solid feces in a healthy individual, although other estimates have put the number as low as 30 percent. Both estimates demonstrate that billions of bacteria are released from the body. Ray (2002) found a mean of 7.5 log10 VRE per gram of stool. Boyce (2007) found some patients with diarrhea who were excreting MRSA in quantities between 107 – 109 CFU/gram of stool. Using a toilet puts high numbers of bacteria into the toilet bowl, where they can become aerosolized during fl ushing. Even fl ushing an empty toilet bowl can aerosolize bacteria from inside the bowl (Knowlton, 2018). Thus, a focus on toilets as a prime vector of bacterial dissemination seems justifi ed. • Saliva: Saliva is colonized with many bacteria. Lamont (2010) estimated that there are 1x108 bacteria per milliliter of saliva and Sender estimated 1x109 bacteria per milliliter. Droplets of saliva are spread into the environment by talking, breathing, coughing, sneezing, singing and other activities. These activities occur within and outside healthcare facilities, so this risk is not unique to healthcare. Any oral suctioning is an additional risk for contamination of the environment. • Skin: Skin is the body's largest organ at ~1.8m2 and provides a diverse environment for bacteria, including warm damp areas, cooler dr yer areas, hair, no hair and openings into the body (ears, nose, mouth, anus, etc.). Estimates of skin shedding calculate that of the 19 million skin cells on our body, 30,000 to 4 0,0 0 0 skin cells are shed daily (American Academy of Dermatology Association, 2018). Meadow (2015) repor ts that humans shed 1x106 particles of >0.5 micrometers per hour, many of which contain bacteria, although the exact percentage is diffi cult to determine. However, there are up to 1x1011 bacteria per m2 on skin, so skin cell shedding involves disseminating signifi cant numbers of bacteria. Patients with burns, autoimmune diseases, morbid obesity or eczema would likely have higher rates of shedding. Patient Colonization: Implications and Possible Solutions for Contamination of the Healthcare Environment By Peter Teska, Jim Gauthier and Carol Calabrese

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