Disinfection and sterilization of instruments is a crucial point in any midwifery practice. It is the procedure by which health care professionals ensure that all reusable medical devices do not harbor any biological matter before the next use. Sterilization causes biological entities to be killed, removed or deactivated either by physical or chemical means, where as disinfection causes most but not bacterial spores.
DEFINITIONS
Disinfection: Disinfection describes a process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects. In health-care settings, objects usually are disinfected by liquid chemicals.
Factors that affect the efficacy of both disinfection and sterilization include prior cleaning of the object; organic and inorganic load present; type and level of microbial contamination; concentration of and exposure time to the germicide; physical nature of the object (e.g., crevices, hinges, and lumens); presence of biofilms; temperature and pH of the disinfection process; and in some cases, relative humidity of the sterilization process (e.g., ethylene oxide).
Unlike sterilization, disinfection is not sporicidal. A few disinfectants will kill spores with prolonged exposure times (3–12 hours); these are called chemical sterilants. At similar concentrations but with shorter exposure periods (e.g., 20 minutes for 2% glutaraldehyde), these same disinfectants will kill all microorganisms except large numbers of bacterial spores; they are called high-level disinfectants. Low-level disinfectants can kill most vegetative bacteria, some fungi, and some viruses in a practical period of time (≤10 minutes). Intermediate-level disinfectants might kill mycobacteria, vegetative bacteria, most viruses, and most fungi but do not necessarily kill bacterial spores.
Cleaning: is the removal of foreign material (e.g., organic material) from objects and is normally accomplished using water with detergents or enzymatic products. If soiled materials dry or bake onto the instruments, the removal process becomes more difficult and the disinfection or sterilization process can become ineffective. Surgical instruments should be presoaked or rinsed to prevent drying of blood and to soften or remove blood from the instruments.
For instrument cleaning, a neutral or near-neutral pH detergent solution is commonly used because such solutions generally provide the best material compatibility profile in addition to good soil removal. If your instruments are not rinsed properly, low pH detergents may break down the protective surface of stainless steel instruments and cause black staining. Likewise, alkaline detergents may leave surface deposits that cause a brown stain and interfere with the smooth operation of the instrument. Rinse your instruments in cool water. Hot water can cause protein substances to coagulate. If desired, soak your surgical instruments in cool water with an enzymatic detergent. The detergent helps to dissolve the proteins and break down oils. Then, the instruments may be cleaned by hand or mechanically in a washer or ultrasonic bath
Sterilization: Sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out in health-care facilities or home-health providers by physical or chemical methods. Steam under pressure, dry heat, EtO gas, and liquid chemicals are the principal sterilizing agents used.
Media of Disinfection
Alcohol
Chlorine and chlorine compounds
Formaldehyde
Glutaraldehyde
Hydrogen peroxide
Iodophors
Ortho-phthalaldehyde (OPA)
Peracetic acid
Phenolics
Quaternary ammonium compounds
CATEGORIES OF PATIENT CARE ITEMS AND INSTRUMENTS
1. CRITICAL ITEMS:
Critical items deal with a high risk of infections if contaminated with any biological agents. These items may come in contact with internal tissues and the vascular system, so the sterility of these items is prioritized above all. Because any microbial induction could lead to the transmission of disease, surgical instruments, implants, catheters and probes are examples of this category.
2. SEMICRITICAL ITEMS:
These items have contact with mucous membrane and non-intact skin. Items should be free from all microorganisms, but as they are less critical than the above category, a small number of bacterial spores are permissible. A laryngoscope blade is an example in this category.
3. NONCRITICAL ITEMS:
Like semi-critical items, these items are in contact with intact skin but not with mucous membrane. As the skin is the most substantial effective barrier to most of the microorganism, so here sterility is not a big issue. Blood pressure cuffs, bedpans, and stethoscopes are some examples of this category.
To be continued next week….
