Infection control is the discipline concerned with preventing nosocomial infection or healthcare-associated infection, a practical (rather than academic) sub-discipline of epidemiology. It is an essential, though often underrecognized and undersupported, part of the infrastructure of health care. Infection control and hospital epidemiology are akin to public health practice, practiced within the confines of a particular health-care delivery system rather than directed at society as a whole.
Infection control addresses factors related to the spread of infections within the health-care setting (whether patient-to-patient, from patients to staff and from staff to patients, or among-staff), including prevention (via hand hygiene/hand washing, cleaning/disinfection/sterilization, vaccination, surveillance), monitoring/investigation of demonstrated or suspected spread of infection within a particular health-care setting (surveillance and outbreak investigation), and management (interruption of outbreaks). It is on this basis that the common title being adopted within health care is "Infection Prevention & Control."
Infection control in healthcare facilities
Aseptic technique is a key component of all invasive medical procedures. Similarly, infection control measures are most effective when Standard Precautions (health care) are applied because undiagnosed infection is common.
Independent studies by Ignaz Semmelweis in 1847 in Vienna and Oliver Wendell Holmes in 1843 in Boston established a link between the hands of health care workers and the spread of hospital-acquired disease. The Centers for Disease Control and Prevention (CDC) has stated that “It is well documented that the most important measure for preventing the spread of pathogens is effective handwashing.”  In the United States, hand washing is mandatory in most health care settings and required by many different state and local regulations.
In the United States, Occupational Safety and Health Administration (OSHA) standards require that employers must provide readily accessible hand washing facilities, and must ensure that employees wash hands and any other skin with soap and water or flush mucous membranes with water as soon as feasible after contact with blood or other potentially infectious materials (OPIM).
Drying is an essential part of the hand hygiene process. In November 2008, a non-peer-reviewed study was presented to the European Tissue Symposium by the University of Westminster, London, comparing the bacteria levels present after the use of paper towels, warm air hand dryers, and modern jet-air hand dryers. Of those three methods, only paper towels reduced the total number of bacteria on hands, with "through-air dried" towels the most effective.
The presenters also carried out tests to establish whether there was the potential for cross-contamination of other washroom users and the washroom environment as a result of each type of drying method. They found that:
- the jet air dryer, which blows air out of the unit at claimed speeds of 400 mph, was capable of blowing micro-organisms from the hands and the unit and potentially contaminating other washroom users and the washroom environment up to 2 metres away
- use of a warm air hand dryer spread micro-organisms up to 0.25 metres from the dryer
- paper towels showed no significant spread of micro-organisms.
In 2005, in a study conducted by TUV Produkt und Umwelt, different hand drying methods were evaluated. The following changes in the bacterial count after drying the hands were observed:
|Drying method||Effect on bacterial count|
|Paper towels and roll||Decrease of 24%|
|Hot-air drier||Increase of 117%|
Cleaning, disinfection and sterilization
Sterilization is a process intended to kill all microorganisms and is the highest level of microbial kill that is possible. Sterilizers may be heat only, steam, or liquid chemical. Effectivness of the sterilizer (e.g., a steam autoclave) is determined in three ways. First, mechanical indicators and gauges on the machine itself indicate proper operation of the machine. Second heat sensitive indicators or tape on the sterilizing bags change color which indicate proper levels of heat or steam. And, third (most importantly) is biological testing in which a highly heat and chemical resistant microorganism (often the bacterial endospore) is selected as the standard challenge. If the process kills this microorganism, the sterilizer is considered to be effective. It should be noted that in order to be effective, instruments must be cleaned, otherwise the debris may form a protective barrier, shielding the microbes from the lethal process. Similarly care must be taken after sterilization to ensure sterile instruments do not become contaminated prior to use.
Disinfection refers to the use of liquid chemicals on surfaces and at room temperature to kill disease causing microorganisms. Disinfection is a less effective process than sterilization because it does not kill bacterial endospores.
Sterilization, if performed properly, is an effective way of preventing bacteria from spreading. It should be used for the cleaning of the medical instruments or gloves, and basically any type of medical item that comes into contact with the blood stream and sterile tissues.
There are four main ways in which such items can be sterilized: autoclave (by using high-pressure steam), dry heat (in an oven), by using chemical sterilants such as glutaraldehydes or formaldehyde solutions or by radiation (with the help of physical agents). The first two are the most used methods of sterilizations mainly because of their accessibility and availability. Steam sterilization is one of the most effective types of sterilizations, if done correctly which is often hard to achieve. Instruments that are used in health care facilities are usually sterilized with this method. The general rule in this case is that in order to perform an effective sterilization, the steam must get into contact with all the surfaces that are meant to be disinfected. On the other hand, dry heat sterilization, which is performed with the help of an oven, is also an accessible type of sterilization, although it can only be used to disinfect instruments that are made of metal or glass. The very high temperatures needed to perform sterilization in this way are able to melt the instruments that are not made of glass or metal.
Steam sterilization is done at a temperature of 121 C (250 F) with a pressure of 106 kPa (15 lbs/in2). In these conditions, unwrapped items must be sterilized for 20 minutes, and wrapped items for 30 minutes. The time is counted once the temperature that is needed has been reached. Steam sterilization requires four conditions in order to be efficient: adequate contact, sufficiently high temperature, correct time and sufficient moisture. Sterilization using steam can also be done at a temperature of 132 C (270 F), at a double pressure. Dry heat sterilization is performed at 170 C (340 F) for one hour or two hours at a temperature of 160 C (320 F). Dry heat sterilization can also be performed at 121 C, for at least 16 hours.
Chemical sterilization, also referred to as cold sterilization, can be used to sterilize instruments that cannot normally be disinfected through the other two processes described above. The items sterilized with cold sterilization are usually those that can be damaged by regular sterilization. Commonly, glutaraldehydes and formaldehyde are used in this process, but in different ways. When using the first type of disinfectant, the instruments are soaked in a 2-4% solution for at least 10 hours while a solution of 8% formaldehyde will sterilize the items in 24 hours or more. Chemical sterilization is generally more expensive than steam sterilization and therefore it is used for instruments that cannot be disinfected otherwise. After the instruments have been soaked in the chemical solutions, they are mandatory to be rinsed with sterile water which will remove the residues from the disinfectants. This is the reason why needles and syringes are not sterilized in this way, as the residues left by the chemical solution that has been used to disinfect them cannot be washed off with water and they may interfere with the administered treatment. Although formaldehyde is less expensive than glutaraldehydes, it is also more irritating to the eyes, skin and respiratory tract and is classified as a potential carcinogen.
Other sterilization methods exist, though their efficiency is still controversial. These methods include gas sterilization, UV sterilization, and sterilization with other chemical agents such as peroxyacetic acid, paraformaldehyde and gas plasma sterilization.
Infections can be prevented from occurring in homes as well. In order to reduce their chances to contract an infection, individuals are recommended to maintain a good hygiene by washing their hands after every contact with questionable areas or bodily fluids and by disposing the garbage at regular intervals to prevent germs from growing.
Personal protective equipment
Personal protective equipment (PPE) is specialized clothing or equipment worn by a worker for protection against a hazard. The hazard in a health care setting is exposure to blood, saliva, or other bodily fluids or aerosols that may carry infectious materials such as Hepatitis C, HIV, or other blood borne or bodily fluid pathogen. PPE prevents contact with a potentially infectious material by creating a physical barrier between the potential infectious material and the healthcare worker.
In the United States, the Occupational Safety and Health Administration (OSHA) requires the use of Personal protective equipment (PPE) by workers to guard against blood borne pathogens if there is a reasonably anticipated exposure to blood or other potentially infectious materials.
Components of Personal protective equipment (PPE) include gloves, gowns, bonnets, shoe covers, face shields, CPR masks, goggles, surgical masks, and respirators. How many components are used and how the components are used is often determined by regulations or the infection control protocol of the facility in question. Many or most of these items are disposable to avoid carrying infectious materials from one patient to another patient and to avoid difficult or costly disinfection. In the United States, OSHA requires the immediate removal and disinfection or disposal of worker's PPE prior to leaving the work area where exposure to infectious material took place.
Microorganisms are known to survive on non-antimicrobial in animate ‘touch’ surfaces (e.g., bedrails, over-the-bed trays, call buttons, bathroom hardware, etc.) for extended periods of time. This can be especially troublesome in hospital environments where patients with immunodeficiencies are at enhanced risk for contracting nosocomial infections.
Products made with antimicrobial copper alloy (brasses, bronzes, cupronickel, copper-nickel-zinc, and others) surfaces destroy a wide range of microorganisms in a short period of time. The United States Environmental Protection Agency has approved the registration of 355 different antimicrobial copper alloys that kill E. coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Enterobacter aerogenes, and Pseudomonas aeruginosa in less than 2 hours of contact. Other investigations have demonstrated the efficacy of antimicrobial copper alloys to destroy Clostridium difficile, influenza A virus, adenovirus, and fungi. As a public hygienic measure in addition to regular cleaning, antimicrobial copper alloys are being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil.
Vaccination of health care workers
Health care workers may be exposed to certain infections in the course of their work. Vaccines are available to provide some protection to workers in a healthcare setting. Depending on regulation, recommendation, the specific work function, or personal preference, healthcare workers or first responders may receive vaccinations for hepatitis B; influenza; measles, mumps and rubella; Tetanus, diphtheria, pertussis; N. meningitidis; and varicella. In general, vaccine do not guarantee complete protection from disease, and there is potential for adverse effects from receiving the vaccine.
Post exposure prophylaxis
In some cases where vaccines do not exist Post Exposure prophylaxis is another method of protecting the health care worker exposed to a life threatening infectious disease. For example, the viral particles for HIV-AIDS can be precipitated out of the blood through the use of an antibody injection if given within 4 hours of a significant exposure.
- ↑ CDC Guideline for Hand Hygiene in Health-Care Settings
- ↑ CDC General information on Hand Hygiene
- ↑ http://www.safechemdirect.co.uk
- ↑ OSHA Bloodborne Pathogens Regulations 1910.1030
- ↑ According to p. 35 of the Redway/Fawdar presentation, "Note: this study has not been peer reviewed but it is intended that the test methods described in this document are provided in sufficient detail to allow replication by those who wish to confirm the results."
- ↑ TÜV Produkt und Umwelt GmbH Report No. 425-452006 A report concerning a study conducted with regard to the different methods used for drying hands; September 2005
- ↑ 7.0 7.1 7.2 7.3 (Miller, Chris H.. Infection Control and Management of Hazardous Materials for the Dental Team, 4th Edition. Mosby Elsevier Health Science, 2010. chpt 11).
- ↑ Template:Cite web
- ↑ OSHA Bloodborne Pathogens Regulations 1910.1030(d)(2)(i)
- ↑ OSHA 1910.1030(d)(3)(vii)
- ↑ Wilks, S.A., Michels, H., Keevil, C.W., 2005, The Survival of Escherichia Coli O157 on a Range of Metal Surfaces, International Journal of Food Microbiology, Vol. 105, pp. 445–454. and Michels, H.T. (2006), Anti-Microbial Characteristics of Copper, ASTM Standardization News, October, pp. 28-31
- ↑ 12.0 12.1 Copper Touch Surfaces
- ↑ CDC Vaccine Site
- Association for Professionals in Infection Control and Epidemiology is primarily composed of infection prevention and control professionals with nursing or medical technology backgrounds
- The Society for Healthcare Epidemiology of America is more heavily weighted towards practitioners who are physicians or doctoral-level epidemiologists.
- The Provincial Infection Control Network of British Columbia
- Regional Infection Control Networks
- The Certification Board of Infection Control and Epidemiology, Inc.
- Association for Professionals in Infection Control and Epidemiology