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Noninvasive devices

The category of noninvasive medical devices includes the ones that are used as mechanical barriers, such as dressings and bandages, which come in contact with injured skin.

The first stage of biofilm formation on a surface of a medical device is the adherence of microorganisms on the material, followed by proliferation and formation of microcolonies. The number of bacteria in a microcolony is large enough to form a very complex structure composed of several layers of cells. The microbial cells are further encapsulated in an EPS matrix, which contains proteins, nucleic acids, lipids, and polysaccharides. EPSs influence the adhesion of other microorganisms and has a very important role in the protection of biofilm to external factors. Because of this extracellular matrix formed around microorganisms, biofilms provide a very high resistance against antibiotics compared with bacterial microcolonies (Davey and O’Toole, 2000).

In medical terms, an efficient cleaning of noninvasive devices is necessary for all the previously mentioned types. Even if we talk about the first category, which come in contact with intact skin, these must be properly cleaned. Different studies have demonstrated that the main species spread on the membranes of the stethoscopes are skin microorganisms, which can cause several skin diseases that can be easily transmitted by using them on different patients (Grandiere-Perez et al., 2015). Inanimate surfaces proved to have a great tendency to allow attachment and growth of different types of microorganisms that could be transmitted among patients and hospital personnel (Krameret al., 2006). The most known example is the membrane of the stethoscope, which is often utilized as a simple diagnosis device and comes in contact with almost every patient. This simple device proved to be a favorable instrument for the spread of bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile, acting as a vector for transmitting bacteria to skin (Merlin et al., 2009; Alleyne et al., 2009). Mangi and Andriole found on the surface of diaphragms up to 125 types of microorganisms, of which 15 were classified as potential pathogens (Mangi and Andriole, 1972). Nowadays the problem concerning colonization on stethoscopes still persists in the hospital environment (Young, 2014; Alvarez et al., 2014). A proposed solution to this problem would be an accurate cleaning of the stethoscopes using antiseptics before and after they are used on each patient (Alvarez et al., 2014). The most used method to properly clean the membranes includes isopropyl alcohol pads and ethanol-based hand sanitizer (EBHS), and it is vaguely known that isopropyl would have a better effect than ethanol-based products (Lecat et al., 2009).

Injured skin might come further in contact with microorganisms through medical devices during the process of healing, and therefore healing should take place in a medium as “clean” as possible. A possible contamination can lead to slow healing, tissue destruction, or even, in severe cases, can cause hazardous infections in the human body. Nowadays the most common way to prevent such things happen is the use of several dressings and bandages whose main purpose is to act as a barrier so that microorganisms cannot pass to the injured tissue. In order to achieve a successful outcome, besides the basic criteria, such as biocompatibility and nontoxicity, dressings and bandages must have an inhibitory activity against potential pathogens (Monaco and Lawrence, 2003; Gosain and DiPietro, 2004; Korting et al., 2011).

Nowadays, the main purpose for all medical devices that come in contact with injured skin is to reduce the microbial colonization. Most used methods are considered to be the modification of material surfaces, the use of nonadherent materials to prevent bacterial adhesion, or the use of materials with antimicrobial properties to eliminate cells that come in contact with the surface. Although the use of nonadherent materials is continuously studied, a material that can lead to a complete inhibition of microbial adhesion has not yet been discovered. Instead, the use of materials with antiseptic properties has already proved to be an effective method of preventing infections of wounds (Drenkard and Ausubel, 2002).

Biofilm formation is a common problem that can affect noninvasive medical devices, which is a problem in public health sector because of the increased resistance to inhibitors. Therefore prevention of biofilm through well-established hygiene protocols and the use of strategic materials seem to be the best solutions.

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