Sunday, July 13, 2014

Infection Control: Basic Concepts and Practices

 Hand Hygiene


The natural flora of the mouth and the bowel has bacterial concentrations up to 10^10 per ml and are significant reservoirs of nosocomial or hospital pathogens. In hospitalised patients, the skin may become colonised with multidrug resistant (MDR) pathogens, and infected wounds and other lesions are also potential sources of cross-infecting organisms. 

Pathogenic organisms from colonized and infected patients (and sometimes from the environment) transiently contaminate the hands of staff during normal clinical activities and can then be transferred to other patients. Hand transmission is one of the most important methods of spread of infectious agents in health care facilities. Proper hand hygiene is an effective method for preventing the transfer of microbes between staff and patients.

The microbial flora of the skin consists of resident and transient microorganisms. Resident organisms (e.g., coagulase negative staphylococci, diphtheroids) survive and multiply in the superficial skin layers. The transient microbial flora of the skin consists of recent contaminants that survive only for a limited period of time. These microorganisms (e.g., S. aureusE. coli, enterococci) may be acquired by contact with the normal flora or colonised or infected sites of the patient or from the inanimate hospital environment. If the skin of staff members' hands is damaged, the bacterial count on the skin becomes higher. There is also a risk for colonisation with bacteria not normally belonging to the hand flora.
Three levels of decontamination of hands are recognized.

Social handwashing with plain soap and water removes most transient microorganisms from moderately soiled hands.

Hygienic handwashing or disinfection is a procedure where an antiseptic detergent preparation is used for washing or hands are disinfected with alcohol (alcoholic rub). This is a more effective method to remove and kill transient microorganisms.

The distinction between the need for social handwashing and hygienic hand washing may not always be clear. A thorough social hand wash may be appropriate if disinfectants are not available.

Surgical handwashing is performed with the aim of removing and killing the transient flora and decreasing the resident flora in order to reduce the risk of wound contamination if surgical gloves become damaged. Agents are the same as for the hygienic hand wash.

A defined technique for decontamination of hands is probably of greater importance than the agent used. The technique presented in Figure 4.1 is recommended.

When to wash hands
Social handwashing
  • before handling food, eating
  • before feeding the patient
  • after visiting the toilet.
Hygienic handwashing or alcoholic rub
  • before and after nursing the patient
  • before performing invasive procedures
  • before caring for susceptible patients (such as the immunocompromised)
  • before and after touching wounds, urethral catheters, and other indwelling devices
  • before and after wearing gloves
  • after contact with blood secretions or else following situations in which microbial contamination is likely to have occurred
  • after contact with a patient known to be colonised with a significant nosocomial pathogen (such as MRSA, MDRKlebsiella)
An alcoholic hand rub, ideally from a dispenser at the patient's bedside is the most efficient and least time consuming procedure for hand decontamination.
Surgical handwashing
  • before all surgical procedures
Watches and rings reduce hand washing/disinfection effectiveness and should be removed during hand hygiene. Some suggest that they not be worn in patient care.

Social hand washing
In social hand washing, vigorous and mechanical friction is applied to all surfaces of lathered hands using plain soap and water for at least 10 seconds using a defined technique (Fig. 4.1). The hands are rinsed under a stream of water and dried with paper towel.  In the absence of running water, a clean bowl of water should be used. The bowl should be cleaned and water changed between each use. Alternatively, a drum with a drain spout could be elevated to serve as running water. Similarly, in the absence of paper towels, a small clean cloth could be used, but the towel should not be used for extended communal use and should be discarded after each use into a bag designated for laundering and reuse.
In places where there is frequent disruption of water supply, water should be stored in large receptacles whenever water is available. The water should be free from infectious agents.

Recommended hand wash agents
Hygienic hand washing/disinfection
  • 4% chlorhexidine gluconate/detergent solution
  • Povidone - iodine/detergent solution containing 0.75% available iodine
Wet hands with clean (running) water or, if not available, from water in a bowl. Apply cleanser (3-5 ml) depending on the product or thoroughly lather with soap.  Wash the hands for 10-15 seconds, applying friction over all hand surfaces, rinse and dry as described above.
  • 0.5% chlorhexidine or povidone-iodine in 70% isopropanol or ethanol
  • 60% isopropanol or 70% ethanol without antiseptic
Apply not less than 3ml of the preparation to the hands and rub to dryness (approximately 30 seconds). Alcohol is more effective than aqueous antiseptic solutions, but a preliminary wash may be needed for physically soiled hands. Alcohol is an effective alternative when there is no water or towels readily available and there is need for rapid hand disinfection. Alcohol products with emollients added will cause less skin irritation and drying to hands (1-3% glycerol).

Surgical hand washing/disinfection
Agents for surgical hand washing are the same as for the hygienic hand wash. The difference is the time of scrub that is increased to 2-3 min and should include wrists and forearms. If an alcoholic preparation is used, two applications of 5ml each rubbed to dryness are suggested.
  • Sterile disposable or autoclavable nailbrushes may be used to clean the fingernails only, but not to scrub the hands.
  • A brush should only be used for the first scrub of the day.
  • After hand washing with soap and water, a hand rub with an alcoholic base formulation (70%) should be used if possible. This enhances the destruction or inhibition of resident skin flora.
  • Sterile towels should be used to dry the hands thoroughly after washing and before alcohol is applied.
Important Points to Note
  • When bar soap is in use, it should be kept dry to prevent contamination with microorganisms that grow in moist conditions.
  • Liquid soap dispensers should be regularly cleaned and maintained.
  • Gloves should not be regarded as a substitute for hand hygiene. A glove is not always a complete impermeable barrier (20-30% of surgical gloves are punctured during surgery). However, gloves reduce very substantially the number of microorganisms being transferred to the patient or to the HCW who is wearing the gloves. Gloves also provide some protection against the transmission of blood-borne viruses.
  • In an epidemic situation, hand hygiene and the use of gloves are important protective measures to prevent the transmission of infectious agents to susceptible patients or staff. The same glove must not be worn from one patient to another patient, or between clean and dirty procedures on the same patient.
  • An alcoholic rub or hand wash should be performed after removing gloves and before sterile gloves are worn.
In areas where gloves are not readily available, latex gloves can be washed with soap and water, dried, powdered, sterilized or high level disinfected and reused. Sterilisation is preferable for surgical procedures.

Minimal requirements
  • Watches and rings reduce hand washing effectiveness and should be removed.
  • Wash hands with soap and water and dry thoroughly with a clean towel at the start of a clinical shift or if hands become grossly soiled.
  • Decontaminate hands with a hand disinfectant or alcoholic rinse or rub between each patient contact.
  • Perform a surgical scrub before each operation.
  • Wear gloves as necessary to reduce transfer of organisms to patient and to reduce transmission of blood borne viruses.
  1. Standard principles for preventing hospital-acquired infections. Journal of Hospital Infection 2001;47(Suppl):S21-S37.
  2. Guideline for Hand Hygiene in Healthcare Settings - 2002. MMWR 2002;51(RR-16):1-44.

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