Infection Control and Asepsis

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Infection Control and Asepsis


History and Scientific Foundations

Applications and Research

Impacts and Issues

Primary Source Connection



Steps that are taken to reduce or prevent infection in health care settings are known as infection control. Almost two million people in the United States acquire a nosocomial (hospital or health-care-related) infection each year, adding more than five billion dollars to health care costs annually. Most hospitals have dedicated infection control practitioners on staff, whose job it is to oversee the infection control procedures as specified by the United States Centers for Disease Control and Prevention (CDC) and the Association for Professionals in Infection Control and Epidemiology (APIC). Infection control professionals (ICPs) are usually nurses, physicians, medical technologists, or epidemiologists, and their main focus is to investigate and gather data about existing infections in order to take the appropriate actions to contain them and prevent future infections.

History and Scientific Foundations

Before infection control and asepsis were recognized, surgery was often a death sentence for the patient. Up until the mid-nineteenth century, the death rate following surgeries was over 50%. Instead of being a life-saving measure, surgery was a desperate last resort when all other treatments had failed. British surgeon and scientist Joseph Lister (1827–1912) changed the role of surgery by demonstrating the value of infection control. When he applied a spray of disinfectant over a patient's wound during surgery, Lister showed that post-operative infections could be markedly reduced. Later, this was shown to be due to the killing of bacteria that were present in the air of the operating room or on the clothing or gloves of the health care providers. By killing the bacteria before or immediately after they contacted the wound, infection was minimized. In the decades after Lister's method became popular, post-operative patient deaths dropped to less than 1%. This was the beginning of the modern concept of aseptic technique.

Asepsis is defined as the absence or removal of disease-causing (pathogenic) microorganisms. Compounds that are used to achieve asepsis are termed antiseptics. Asepsis is designed to leave a surface sterile, free from microorganisms, and is used in surgery and for procedures where surfaces of medical equipment such as instruments or wound dressings will come in contact with sterile areas of the body. Sanitization is sufficient for other surfaces in the healthcare setting (and at home or in the community) to prevent infections. Sanitization does not leave surfaces sterile, but reduces the amount of disease-causing microorganisms to an insignificant level.

The cornerstone of infection control involves breaking the cycle of infection and interrupting the transmission of disease-causing organisms. The concept of standard precautions is the infection control foundation for healthcare workers, and is used universally in the developed world. Standard precautions assumes that any patient's body fluid, tissue, or secretion could be potentially infectious until determined otherwise, and along with handwashing, barrier protection such as latex (or a latex alternative) gloves, disposable gowns, and masks should be used as appropriate to avoid exposure to them. Likewise, barrier protections are used to prevent patients from being exposed to body fluids or surface disease-causing organisms that might be present on or in the healthcare worker.

Additional infection control measures are based upon isolating or grouping together (cohorting) persons with infectious diseases according to how the disease is spread. Isolation means setting apart a person with a known infection. Additional sets of precautions are used for persons with documented infections and include airborne precautions, droplet precautions, and contact precautions. When airborne precautions are implemented, as with a person who has an active tuberculosis infection, negative-pressure airflow rooms assure that the extremely small tuberculosis bacteria will not enter other patient rooms, and specialized masks are used by both hospital staff and the patient to prevent the spread of tuberculosis. Droplet precautions are used for persons with known or suspected diseases that can be spread through larger infectious particles that are released by coughing or sneezing, such as polio or measles. Gown, masks, and gloves are usually worn by healthcare personnel and visitors when they are in the room of a patient with droplet precautions. Contact precautions are used with persons who have infections that can be transmitted by direct or indirect skin-to-skin contact, such as wounds infected with resistant bacteria. Regardless of the type of specialized precautions implemented in persons with infections, standard precautions are always additionally in effect.


ASEPSIS: Without germs, more specifically without microorganisms.

BIOFILM: Biofilms are populations of microorganisms that form following the adhesion of bacteria, algae, yeast, or fungi to a surface. These surface growths can be found in natural settings such as on rocks in streams, and in infections such as can occur on catheters. Microorganisms can colonize living and inert natural and synthetic surfaces.

COHORTING: Cohorting is the practice grouping persons with like infections or symptoms together in order to reduce transmission to others.

INFECTION CONTROL PROFESSIONAL (ICP): Infection control professionals are a group of nurses, doctors, laboratory workers, microbiologists, public health officials, and others who have specialized training in the prevention and control of infectious disease. Infection control professionals develop methods to control infection and instruct others in their use. These methods include proper hand washing, correct wearing of protective masks, eye-guards, gloves, and other specialized clothing, vaccination, monitoring for infection, and investigating ways to treat and prevent infection. Courses and certifications are available for those wishing to become infection control professionals.

ISOLATION: Isolation, within the health community, refers to the precautions that are taken in the hospital to prevent the spread of an infectious agent from an infected or colonized patient to susceptible persons. Isolation practices are designed to minimize the transmission of infection.

NOSOCOMIAL INFECTION: A nosocomial infection is an infection that is acquired in a hospital. More precisely, the Centers for Disease Control in Atlanta, Georgia, defines a nosocomial infection as a localized infection or one that is widely spread throughout the body that results from an adverse reaction to an infectious microorganism or toxin that was not present at the time of admission to the hospital.

STANDARD PRECAUTIONS: Standard precautions are the safety measures taken to prevent the transmission of disease-causing bacteria. These include proper hand washing, wearing gloves, goggles, and other protective clothing, proper handling of needles, and sterilization of equipment.

Other key elements to infection control in the healthcare setting include disposing infectious waste (such as gloves and wound dressings) in separate containers that receive special handling and are labeled “biohazard”, disposing of needles, scalpels, and other sharp medical equipment in thick, biohazard labeled containers, limiting patient or visitor exposures, and specialized housekeeping and laundry methods.

Asepsis has long been a valuable means of infection control. One of the first laboratory procedures a microbiology student learns is to wipe down the working surface with an alcohol solution before and after doing any work involving bacteria. This simple step kills most bacteria that are adhering to the work surface. This is because the alcohol dissolves the membrane(s) of bacteria. Bacterial membranes are composed mainly of phospholipids—molecules that have a water-loving (hydrophilic) ends and a central portion that is waterhating (hydrophobic). This allows phospholipids to spontaneously associate with the hydrophilic portions oriented to the outside of the membrane and the hydrophobic regions buried inside; this products a barrier that is vital for the structure and the survival of the bacteria. Alcohol, which is also hydrophobic, can induce hydrophobic portions of the phospholipids to associate with it instead of remaining as an intact membrane. As a result, the bacterial membrane dissolves, killing the microbe. The simple act of wiping down a work surface prevents the spread of potentially harmful bacteria.

Applications and Research

Many infections are contagious and so are capable of being spread from person to person and from another host to a person. People may even contaminate themselves and contract an infection. An example of the latter is the fecal-oral route, where hands soiled by feces during a bowel movement and which have not been properly cleaned come in contact with in the mouth or other parts of the body. A common example is the infections that occur in day care facilities. Infants can handle their soiled diaper and subsequently put a hand in their mouth or another persons's mouth. Another example is at the other end of the age spectrum. Elderly people who may be incontinent and whose attentiveness to their sanitary habits may have deteriorated can unknowingly transfer feces to the urinary tract through inadequate hygiene after a bowel movement. This route of transfer can also allow the fecal bacteria to enter the bloodstream. The subsequent blood infection (sepsis) can spread through the body quickly, lethally overwhelming the ability of the immune system to fight the infection.

A simple and time-tested way to minimize person to person transmission of microbes is handwashing. Proper handwashing is the most effective way to prevent the spread of infection. In the home, the use of household soap and vigorous scrubbing of the hands for 30–60 seconds has been shown to eliminate most microorganisms of concern from the hands. This is especially important for those who are involved in food preparation, since fecally-acquired bacteria and virus can contaminate food during handling. In a related step, the cleaning of cutting boards and utensils such as knives helps prevent transfer of microbes. As an example, on of the main reasons for the millions of foodborne contamination with the bacterium Campylobacter jejuni that occurs each year in the United States is not washing cutting boards used to process raw poultry before the board is used for another food. The bacteria sticking to the board are transferred to the other food which, if not cooked or undercooked, can cause illness when eaten.

In the hospital setting, handwashing is done according to CDC guidelines. These specify that healthcare providers wash their hands before and after seeing each patient and, if gloves have also been worn, as the final step when the gloves have been removed and put in the proper disposal container. Many hospitals are equipped with an alcohol-based washstand at the foot of each patient bed or in the room. Handwashing using alcohol takes only seconds—the time savings can be important in a healthcare providers busy schedule.

Various infection control procedures are in place in most hospitals to lessen the spread of infection. This is important for several reasons. Firstly, bacteria that are resistant to most antibiotics are becoming more prevalent. An example is methicillin-resistant Staphylococcus aureus (MRSA); the prevalence of MRSA in hospitals has gone from sporatic and rare in the early 1980s to over 90% of all clinical S. aureus isolates in hospitals in the United States and United Kingdom in 2006. In fact, in the UK, MRSA infections now make up over half of all hospital infections. The fact that only a few antibiotics remain effective against MRSA is frightening, and makes control of the bacterium's presence and spread in a hospital critical for patient health and survival.

A second reason for infection control is the emergence of new infectious viral and bacterial diseases that are easily spread from person to person. An example is the viral disease called severe acute respiratory syndrome, or SARS. Another example of a disease that is poised to become a global problem is avian influenza (bird flu). As of 2007, the virus that causes avian influenza, which has been capable of transmission from birds to humans and which has been of limited concern, is adapting to be capable of person to person transmission. The World Health Organization and CDC are monitoring avian influenza cases closely.

Infection control measures are also important because diseases that used to be rampant but which were controlled decades ago are now re-emerging to become a significant health threat. One example is the form of tuberculosis caused by the bacterium Mycobacterium tuberculosis.

Research laboratories and hospitals often have a variety of CDC- and APIC-mandated infection control procedures in place. Depending on the organism being studied or encountered, most countries have a series of mandated safety controls, with more dangerous microbes requiring more stringent safety and infection control measures. One example is the use of filters in the ventilation system that trap bacteria and even particles as small as viruses. The filters prevent the movement of the microbes from the room to other parts of the building or outside. Some work surfaces can be inside of an enclosed structure called a fume hood, which is separate from the rest of the lab. The fume hood can be open to the rest of the room; just having a semienclosed space cuts down on air movement. Fume hoods can also be completely enclosed, with the work begin done by means of plastic gloves that the person slips their hands into. Equipment and other items can be introduced into the chamber of the fume hood by a two-way door that does not allow air inside the fume hood to move to the outside. Even the work surface itself is designed for infection control. A century ago, the work surfaces in labs were made of wood; while pretty, the surfaces had cracks and crevasses that were ideal breeding grounds for infectious bacteria. Modern lab surfaces are made of chemically-resilient plastic that is very smooth, watertight, and free of gaps. The same principle can be used in the operating theater, where the floor is a single, crack-free unit that is made of material that can be easily cleaned.

Another infection control procedure in a hospital is the use of protective hand wear and clothing. This helps protect the health care provider from contamination from a patient, and, because the protective gear is discarded when moving from patient to patient, minimizes the chance that the health care provider will become a vehicle of transfer of an infection. The use of protective gear depends on the risk posed by a patient. For example, the CDC guidelines indicate that if there is a reasonable chance that someone could be exposed to the splashing or spraying of blood (such as can occur in an Ebola infection, where copious bleeding can occur), a protective gown and perhaps a face mask should be worn. The gown may need to be made of a water-resistant material.

Highly infectious patients will tend to be isolated from other patients in a hospital, and wards containing people who are particularly susceptible to infection (such as transplant recipients, whose immune system is usually deliberately suppressed to reduce the chance of rejection of the transplanted organ) may be in an area of the hospital that has less daily traffic. Contact precautions specify that such patients should be housed in a private room or with similarly-affected people.

Infection control actions can also be taken in the community; an example is malaria. The disease is transmitted by mosquitoes, so steps to control mosquito populations, especially during the insect's breeding season, can help lessen the infection. Spraying prime breeding grounds with insecticide is a common strategy. As well, more high-tech science approaches are being used. For example, a program in malaria-prone regions of Africa that releases genetically altered and infertile male mosquitoes has shown promise. The males are unable to successfully mate with female mosquitoes, which reduce the numbers of the next generation. As malaria is transmitted only be female mosquitoes, reduced numbers of new females means there is less opportunity for the spread of malaria. Another simple and effective infection control mechanism for insect-borne diseases is the use of mosquito netting over a bed during sleep. Organizations including WHO and World Vision conduct campaigns that solicit money for the purchase of mosquito netting and the delivery of the netting to rural villages in malaria-prone regions of Africa. This simple step saves many lives by preventing the mosquito-borne transmission of the infection.

The use of antimicrobial or antiviral agents can help overcome an infection and, in the case of vaccines, can prevent someone from contracting an infection. An example of the power of a vaccine is polio. Prior to the 1950s, polio was a dreaded childhood viral illness that paralyzed many children. After the introduction and refinement of two polio vaccines, polio has become a rare event. The Polio Eradication Initiative launched by the World Health Organization (WHO) in 1988 has reduced the global number of polio cases by over 99%. In 2006, four countries had polio epidemics, as compared to 125 countries in 1988.

The WHO campaign also highlights the importance of maintaining an infection control program. During 2006, the interruption of the campaign in Nigeria due to a military conflict caused a renewed polio outbreak. Infection control cannot be done once and then forgotten; vigilance must be continual.

Even with vigilance, infection control can be difficult. An example is the use of antibiotics. In the decades of 1940s–1960s following the introduction of penicillin and the discovery or synthesis of new antibiotics, these agents were hugely successful at dealing with bacterial infections. But, as with the polio campaign, initial success does not guarantee long-term success. Bacteria haven proven to be capable of adaptation to many of the anti-biotics that have been introduced. This resistance can appear within only a few years, and can spread. Strains of enterococci and Staphylococcus aureus that are resistant to virtually all known antibiotics currently in use pose a challenge in patient care.

Antibiotic resistance can spread through a bacterial population quickly because the genetic information that specifies the protein involved in the resistance is often located on a piece of genetic material that is not part of the main chromosome, but which is more mobile. This means that the information is more capable of being transferred from one bacterium to another bacterium that it comes into contact with.

The hospital is a prime breeding ground for antibiotic resistance. The heavy use of antibiotics and disinfectants in a hospital imposes a selection pressure on bacteria. Those bacteria that can adapt to be resistant stand a better chance of surviving and thriving.

Impacts and Issues

Infection control and asepsis will always be fundamentally important measures in hospitals. One reason is evident from the prevalence of hospital-acquired (nosocomial) infections. In the United States, nosocomial infections kill 90,000 patients each year according to CDC, which in 2005 issued new recommendations aimed at lessening the toll from these infections.

Infection control and asepsis are also becoming more important in the prevention of infections, as infectious diseases become more resistant and as new diseases emerge. People are more at risk for infections, especially since the populations of many developed countries are aging. In general, the elderly are increasingly vulnerable to infections as their immune systems and overall resilience declines. As the population of a country like the United States ages, the costs of health care will grow. In 2007, the costs of delivering health care in the United States and elsewhere are skyrocketing, as the many infection control measures and the development of new effective weapons against microbial diseases is expensive. As health care becomes increasingly more expensive to deliver, the ability to supply the needed care becomes more difficult. Governments in countries such as the United States, Canada, and England are recognizing that the current systems of health care are likely not sustainable. Reducing the need for health care by improved infection control is also recognized as an economical, vital strategy to ensure good health for future generations.

Traditionally, infection control strategies for bacterial disease have been geared towards the types of bacteria studied in the laboratory. Scientists now know, however, that these bacteria that live and grow while floating in the lab growth medium are not at all like the populations found in the real world. Infections are often caused by bacteria that grow by adhering to surfaces. These so-called biofilms are more resistant to drugs that would easily kill their floating counterparts. This means that infection control strategies need to change to more realistically deal with the real world of biofilm-caused bacterial infections.

Primary Source Connection

Institutions such as schools, hospitals, and nurseries are especially prone to infectious disease that spread through casual contact or the fecal-oral route. A 2006 outbreak of E. coli in nurseries in Scotland highlighted the importance of institutional hygiene and infectious disease control practices in preventing disease.

Nurseries Told to Clean Up Their Act

FILTHY CONDITIONS have been uncovered at scores of Scotland's nurseries, the Sunday Mail can reveal today.

The alarming hygiene failures at the nurseries can be exposed as suspected cases of potentially fatal E Coli linked to a nursery in Fife hit 25.

Inspectors have ordered 84 nurseries to clean up their act after discovering:

Vermin in a nursery classroom.

Toddlers asked to do their own cleaning with chemicals.

Dishes being washed in a toilet.

Tots being asked to share facecloths.

The Care Commission assessed 2380 nurseries and playgroups.

Of those, 84 were ordered to change their practices on infection control.

Inspectors found signs of vermin in a cabin used as Auchtertyre Primary School's nursery in the Highlands.

Bosses of the school in Kyle of Lochalsh were told to destroy the cabin.

They had been warned about the health hazard last year but took no action.

The warning was repeated in findings published in February, yet the building is still standing.

A spokesman for Highland Council said: “It is planned for demolition.

“Vermin control measures have been and are in place at the school but because of the rural nature of the site, mice can sometimes be an issue.”

At Dundee's Wonderland nursery, staff gave kids chemicals to clean up.

The inspectors reported: “The nursery must review its practice of permitting children to use a chemical cleaning agent to clean the tables.

“Staff should also ensure that cleaning materials remain in the original container.”

At the time of the inspection, the youngsters were eating sandwiches without plates.

The inspectors added: “They should provide plates for the children at meal times to improve hygiene.

Owner Graham MacDonald said: “For years, we had been allowing the children to use anti-bacterial sprays to clean up.

“We thought it was a good way to teach them about hygiene but have stopped it.

“The children do get given plates to eat from but on the day of the inspection, they were having sandwiches.”

Staff at Beauly Playgroup in Invernessshire were told to make changes after inspectors discovered the only sink to wash dishes was in the toilet. Yesterday, the owners were unavailable for comment.

Coringa Day Care in Dundee was told to produce an infection-control procedure immediately and were slammed for using communal bedding and face-cloths. In April, the centre was reopened as Sweeties Day Care.

The new owner, Jane McDonald, is eager to distance herself from the report.

She said: “I am getting antibacterial mats for the children. I will only use bedding for the cots and it will be washed every day.”

Also in April, organisers of the Kiwi Pre-school Playgroup in East Kilbride, Lanarkshire, were told to clean up dirty toilets.

The inspectors’ report said: “The toilet area was uninviting. It was dark and dirty and had not been well maintained.”

A spokesman for South Lanarkshire Council said: “Kiwi Pre-School Playgroup will take forward the points raised and improvements to the toilet area will be in their plan of action.”

Toilets also featured in the inspectors’ remarks about Langholm Primary School Nursery Class in 2005. Toys were found stored there.

The experts said: “The nursery is required to make proper provision for the health and welfare of the children and to ensure appropriate attention to infection control by making alterations to flush mechanisms, washbasin taps and hot water supply and making appropriate arrangements for the storage of play resources.”

A spokesman for Dumfries and Galloway Council said an alternative area had been found to store the toys.

Croft Park Nursery in Airdrie, Lanarkshire, was criticized because food was not being served at the correct temperature.

Janette Rose, of the Early Years Service which runs the nursery, said they had amended their food preparation practice.

A commission spokesman said: “All care staff must adopt the highest standards with regard to hygiene and infection control to minimise the risk to children.”

Himaya Quasem and Heather Greenaway


See AlsoAirborne Precautions; Contact Precautions; Handwashing; Standard Precautions; Water-borne Disease.



Bankston, John. Joseph Lister and the Story of Antiseptics. Hockessin, DE: Mitchell Lane Publishers, 2004.

Lawrence, Jean, and Dee May. Infection Control in the Community. New York: Churchill Livingstone, 2003.


Yale-New Haven Hospital. “YNHH Infection Control; Introduction.” <> (accessed June 13, 2007).

Brian Hoyle