Fomites

4 Key excerpts on "Fomites"

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  eBook - ePub

  Infection Prevention and Control in Healthcare Settings

  • Edward Purssell, Dinah Gould(Authors)
  • 2022(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Box 1.1 ).

  Figure 1.1

  The chain of infection.

  The environment operates as a reservoir for infections in premises where healthcare is delivered (Box 1.2 ). It is also the source of infections acquired in the community (e.g. tetanus, legionnaire’s disease). Animals are reservoirs for a number of infections including rabies, Ebola disease, Lyme disease and exotic emerging infections such as monkeypox (MPX virus) and zika virus.

  Box 1.1 Fomites

  Fomites are defined as inanimate objects that can operate as vehicles for the transmission of an infectious agent. In healthcare settings, they include patient care items (e.g. bedclothes, bedpans, urinals) and environmental surfaces. They often give rise to outbreaks of infection because disinfection has not been undertaken or undertaken poorly.

  Source: Adapted from Kanamori et al. (2017 ).

  Box 1.2 Environmental Reservoirs for Healthcare‐Associated Infection

  In premises where healthcare is delivered, drains and sinks can become heavily contaminated with micro‐organisms and have been identified as reservoirs when outbreaks occur. Problems are compounded when sinks in clinical areas are used for non‐clinical purposes (e.g. to empty washbowls). Innovations to reduce risks include sinks which self‐disinfect with chemicals or heat and ‘waterless wards’ where conventional sinks and plumbing are removed from patient care areas.

  Portal of Exit

  The portal of exit is the path taken by pathogens to escape from the reservoir. Respiratory pathogens (e.g. colds, influenza) are released in coughs, sneezes and spluttered speech. Enteric pathogens causing food‐poisoning escape in vomit and faeces. Skin scales and dust can provide a portal of exit for some bacteria, including those frequently causing healthcare‐associated infection (e.g. Staphylococcus aureus

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  eBook - ePub

  Infection Control in Small Animal Clinical Practice

  • Fergus Allerton, Kelly Bowlt Blacklock, Fergus Allerton, Kelly Bowlt Blacklock(Authors)
  • 2023(Publication Date)
  • CAB International

    (Publisher)

  et al., 2016).

  Control measures include separation between animals to eliminate direct contact, splash and aerosol risks, containment using collection devices and/or absorbent pads or barriers, careful handling of fluids, scrupulous disposal, effective cleaning and disinfection, and rigorous hand hygiene. Procedures should be planned and performed carefully with suitable measures to prevent contamination, which should include skin, mucosal and airway protection for patients and staff.

  2.3.2 Indirect routes of infection

  Indirect transmission of infection involves transferring the infectious organism from its reservoir to a susceptible individual via an intermediate. These can be animate or inanimate Fomites (also known as vehicles). The organism must therefore be capable of contamination of the carrier or fomite and then temporary survival under these conditions.

  The most important animate Fomites are hands – these spread organisms between animals, humans and hand touch sites (Stull and Weese, 2015; Oh et al., 2018). Inanimate Fomites include anything that can become contaminated directly or indirectly by an infectious organism. These include surfaces, equipment, surgical instruments, kennels and cages, food and water bowls, and muzzles, leads and harnesses. Hand touch sites are especially important – these include door, cupboard and drawer handles, phones, keyboards, tablets and other portable devices, stethoscopes, otoscopes and ophthalmoscopes, scissors, forceps and pens. Environmental contamination is particularly important where the source or reservoir of infection is short term (e.g. the organism is only briefly shed or the animal spends only a short time in the clinic) but where the organism can survive for extended periods in the environment, e.g. canine parvovirus, dermatophyte spores, MRSA, MRSP, and Pseudomonas and Acinetobacter spp.

  Fig. 2.1.

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  Infectious Diseases of the Dog and Cat

  • Jane E. Sykes, Craig E. Greene(Authors)
  • 2011(Publication Date)
  • Saunders

    (Publisher)

  Chapter 93

  Environmental Factors in Infectious Disease

  Craig E. Greene, J. Scott Weese and Janet P. Calpin

  Means of Transmission

  The reservoir of an infectious disease is the natural habitat of its causative agent. Organisms such as some Clostridium spp. and systemic mycotic agents such as Blastomyces, Histoplasma, Coccidioides, and Cryptococcus can survive in inanimate reservoirs such as soil and water. Animate reservoirs, known as carriers, can be clinically or subclinically infected with and shed microorganisms that cause disease. Reservoirs and carriers are distinguished from the source of infection, which can be any vertebrate, invertebrate, inanimate object, or substance that enables the infectious agent to come into immediate contact with a susceptible individual. In many cases, the source is the reservoir.

  The transmissibility or communicability of an infection refers to its ability to spread from infected to susceptible hosts. Contagion and transmissibility have been used interchangeably; however, the former implies spread after intimate contact. Transmission can occur between members of the same population (horizontal) or succeeding generations through the genetic material (vertical). Spread of infection to offspring by the placenta, from genital contact at birth, or in the milk is actually horizontal transmission. Not all infectious diseases are transmissible (e.g., systemic mycotic infections originate from soil rather than spreading between individuals).

  Direct contact transmission is probably the most frequent and important means of spread of infection. This transmission involves direct physical contact or close approximation between the reservoir host and the susceptible individual. Venereal transmission of Brucella canis between dogs and bite transfer of feline immunodeficiency virus (FIV) between cats are examples of direct physical contact transmission. Airborne droplets from respiratory, fecal, or genitourinary secretions of dogs and cats generally do not travel farther than 4 or 5 feet unless there are wind currents. Therefore, droplet spread can be considered a form of direct transmission. The spread of infection under such circumstances can usually be limited, as long as fomite transmission is prevented, by ensuring adequate distance between affected and susceptible animals. Aerosol transmission, a subset of airborne transmission, is spread of very small (less than 100 µm diameter) airborne particles that remain aloft, depending on their respective particle size, with smaller particles traveling longer distances. Freshly aerosolized particles containing microbes rarely remain airborne for more than 1 minute unless they are smaller than 5 µm in diameter. Droplet nuclei, which are desiccated aerosolized particles containing resistant microbes, may also be carried alone or on dust particles by air currents for extended periods and distances. Following inhalation, smaller particles also are able to travel to, and become deposited in, lower portions of the respiratory tract than larger particles. Resistant respiratory pathogens such as Mycobacterium tuberculosis and Histoplasma capsulatum are commonly spread by this means. In human hospitals, nosocomial infections with Bordetella pertussis, Staphylococcus aureus, and Streptococcus pyogenes can be spread by these means, although direct contact with secretions and Fomites (see later discussion) is usually more common for the latter two agents.341 S. aureus infections have been a concern because antimicrobial-resistant strains of S. aureus have been transmitted from humans to dogs and cats (see Chapters 34 and 99 ).

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  Infection Prevention and Control at a Glance

  • Debbie Weston, Alison Burgess, Sue Roberts(Authors)
  • 2016(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Vectors such as mosquitoes, fleas, ticks and flies may carry an infectious agent in a purely mechanical way. For example, flies may transmit infectious agents such as Shigella by walking on faeces and then on to food. Alternatively the vector may support growth or changes in the agent, for example in malaria or Lyme disease. Inanimate mechanisms involve the spread of infectious agents by environmental vehicles or by the air. Anything may act as a vehicle including objects, food, water, milk or biological products. Food is a common vehicle for Salmonella and Campylobacter ; wate r is commonly implicated in cholera outbreaks; surgical instruments and implanted devices may be vehicles of staphylococcal infection. Indirect airborne transmission occurs when very tiny particles of infectious agents are carried by dust or droplet nuclei suspended in air. Droplet nuclei may remain suspended for long periods of time and may be blown over great distances. Due to their size (1–5 micrometres, which allows them to be inhaled deep into the lungs and retained) they are particularly dangerous. Examples of infectious agents that are spread in this way are Mycobacterium tuberculosis and measles. Link 5 – Portal of entry A portal of entry is the way in which an infectious agent enters a susceptible host and is usually the same route as the portal of exit from the reservoir (CDC, 2012). Portals of entry by which infectious agents gain access to the human body are: inhalation (respiratory tract) ingestion (gastrointestinal tract) absorption (via mucous membranes, e.g. eyes) inoculation (e.g. inoculation injury) trans-placental (from the mother to the foetus) introduction (e.g

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