Staphylococci

Staphylococci (e.g. Staphylococcus aureus and Staphylococcus epidermidis) are round or spherical-shaped Gram-positive bacteria, and are part of the normal flora found on the skin and mucous membrane of the nasopharynx, urethra and vagina. They can exist in these areas without any adverse effect on the host and those that live on the skin are termed ‘transient’ organisms. Staphylococci can survive for long periods in the air, dust, bedding and clothing, making cleanliness of the perioperative environment paramount (Phillips, 2007). These bacteria are transmitted from the hands of the host to another person, where they can subsequently have significant negative effects. For example, they can enter the wound of a surgical patient and cause a wound infection or worse, because of their ability to develop resistance to antibiotics quickly (Lee & Bishop, 2006). Exotoxins secreted by S. aureus can cause toxic shock syndrome which, if left untreated, can be fatal (Lee & Bishop, 2006; Phillips, 2007). Staphylococci are strongly associated with healthcare-associated (nosocomial) infection (HAI).

Streptococci

Streptococci are responsible for a wide range of diseases and infections. These include throat and wound infections, pneumonia, septicaemia and necrotising fasciitis. Streptococcus pyogenes is frequently implicated in SSIs. Streptococci tend to be more virulent than staphylococci; however, they are much more likely than the latter to be sensitive to penicillin (Nicolette, 2007). Streptococci can be a normal resident of the upper airway, vagina and anus (Lee & Bishop, 2006; Nicolette, 2007) and are spread via direct and indirect contact, causing infection and illness in susceptible populations.

Enterococci

Enterococci are bacteria normally found in the gastrointestinal tract and female genital tract. They cause infections, such as SSI and septicaemia, when they are transmitted via the hands or contaminated equipment to susceptible, high-risk patients, including surgical patients (Nicolette, 2007). They are becoming an increasingly significant hospital pathogen because strains of enterococci have developed resistance to the antimicrobial drug vancomycin, which is the last resort treatment for methicillin-resistant staphylococcal infections (MRSA) (Lee & Bishop, 2006).

Airborne precautions

Airborne transmission of microorganisms involves their spread via minute particles that can remain suspended in the air for extended periods or disseminated in dust particles. Examples of airborne-transmitted diseases are TB and chickenpox. Precautions against these infections require the use of close-fitting, particulate filter, personal respiratory protection devices or a P2 mask capable of filtering particles as small as 0.3 μm (Australian Department of Health and Ageing, 2004; Nicolette, 2007).

Droplet precautions

Droplet transmission involves larger particles generated when a person sneezes or coughs. Droplets are not as robust or long-lived as airborne particles. Examples of diseases transmitted by droplet are influenza and meningococcal infection. The P2 masks are effective in preventing transmission of droplet infections. It is recommended that patients with airborne or droplet infections wear a P2 or equivalent mask when being transported within the hospital to reduce the risk of infecting other people (Australian Department of Health and Ageing, 2004).

Contact precautions

Contact precautions are intended to prevent the transmission of infectious agents, including epidemiologically important microorganisms, which are spread by direct or indirect contact with the patient or a patient’s environment (Siegel et al., 2007). They are applied to patients known to be infected with various epidemiologically significant organisms, including multiresistant organisms (e.g. MRSA, VRE), and when caring for patients with C. difficile infections (Siegel et al., 2007). As these organisms may be present on the patient’s skin, clothing, bed clothes and equipment, health care workers must wear aprons or gowns, gloves, protective eye wear and masks when participating in patient care activities. All items of protective equipment must be disposed of once contact with the patient is completed and hands thoroughly washed. Whenever feasible, these patients should be isolated during their period of hospitalisation (Nicolette, 2007).

Adherence with these precautions decreases the transmission of infectious agents in health care settings (Siegel et al., 2007). However, several observational studies have shown limited adherence to recommended practices by health care workers (Castella et al., 2006; Siegel et al., 2007). Adherence to good infection control practices requires a work environment where there is commitment to safety on the part of management, which includes education, worker participation in safety programs and the provision of appropriate protective equipment (Griffin, 2005; Siegel et al., 2007).

Opening sterile supplies

The circulating nurse provides a link between the sterile field and the sterile supplies required for a surgical procedure.This requires the ability to open and transfer sterile items safely onto the sterile field. Prior to opening sterile items, circulating nurses must wash their hands and carry out the following:

Figure 5-4 Unwrapping a sterile item.

If any doubt exists about the sterility or integrity of the package, it should be discarded. Items that have a peel-back seal (e.g. swabs or sutures) may be suitable for ‘flipping’ onto the sterile field (depending on individual hospital policy). This practice involves using a sterile bowl, on a separate stand away from the sterile instrument trolley(s), into which small sterile items can be ‘flipped’ (Hamlin, 2008). Flipping items directly onto sterile instrument trolleys should be avoided as it may hinder the instrument nurse in setting up the instruments. Worse still, if an item is contaminated during the flipping process, the whole sterile field is contaminated, not just the bowl, which is easily replaced. Whether a package can be safely transferred by flipping will depend on the item and the experience of the circulating nurse. If in doubt, the item should be opened and presented to the instrument nurse, who can use a sponge-holding forceps to take the item safely.

Figure 5-5 Flipping a sterile item into a sterile bowl.

Figure 5-6 Pouring solution into a sterile galipot.

Pouring liquids onto a sterile field

Any fluids added to the sterile field must first be checked by the instrument nurse to ensure that they are the correct fluid and not out of date. Points to remember are:

The surgical scrub

Before surgeons and instrument nurse(s) can prepare or enter a sterile field, they must perform a surgical scrub, followed by the donning of a sterile gown and gloves according to local hospital policy.

The practice of surgical scrubbing is an attempt to reduce SSIs. Although skin cannot be sterilised, it can be made surgically clean by undertaking a surgical scrub (Gruendemann & Mangum, 2001; Tanner et al., 2007). The scrubbing of the nails, hands and forearms with antiseptic solution reduces dirt and contamination, and transient and resident microorganisms, and minimises regrowth of the latter throughout the surgery.

Before the surgical scrub personnel should:

The antimicrobial scrub solution used may well be dictated by hospital policy and/or personal choice; however, alcohol-based products are generally considered the most efficacious (NSW Health, 2007b; Siegel et al., 2007; Tanner et al., 2007). These solutions are in common usage in Europe and are likely to be in widespread use in Australasia in the near future. Currently, aqueous solutions, such as povidone-iodine and chlorhexidine, are the most commonly used antimicrobial scrub solutions in use. The evidence from comparisons of aqueous scrub solutions with alcohol rubs, which contain additional active ingredients, is mixed and a systematic review by Tanner et al. (2008) revealed no difference between alcohol rubs that contain additional active ingredients and aqueous scrubs in reducing SSIs. There is evidence from studies in favour of both forms of hand antisepsis.

Both Australian and New Zealand professional perioperative organisations provide detailed descriptions of the surgical scrub and each operating suite should display the technique for all staff to follow. Although the actual technique may differ between countries, the basic principles for surgical scrubbing are:

Figure 5-7 Rinsing hands and arms—water should flow from hands to the elbow.

Gowning

Sterile gowns are worn to provide a barrier to prevent the transfer of microorganisms to the patient during the surgical procedure. Their manufacture must meet relevant Australian and New Zealand standards for both disposable, resposable (i.e. limited reuse gowns) and reusable gowns to ensure barrier qualities. Reusable and disposable sterile gowns are folded differently and, therefore, the technique for donning may vary.

The main principles for gowning are (Fig 5-8):

Figure 5-8 Donning a reusable linen gown.

Gloving

Closed gloving is the recommended method to don gloves as it reduces the risk of contamination of the sterile gloves by the bare hands. Double gloving is a recommended practice as it reduces the risk of sharps penetration (Australian Department of Health and Ageing, 2004; Tanner & Parkinson, 2006).

With the hands remaining inside the cuffs, remove one glove from the packet with one hand and with the palm of the other hand uppermost, the glove is placed onto the cuff with the fingers of the glove pointing towards the wrist, the thumb down and with the folded edge of the glove flush against the edge of the cuff of the gown.

With both hands working inside the gown sleeves, the thumbs hold onto the edge of the glove cuffs. Using one motion, the glove is stretched out and over the hand and the gown cuff is inserted into the glove. Both the glove and the gown are then grasped, manoeuvring the hand through the cuff into the glove (Fig 5-9). The procedure is repeated for the other hand.

Figure 5-9 Demonstration of closed method of gloving.

The second pair of gloves are then donned by sliding each gloved hand into the second pair.

Once both pairs of gloves are donned, there is one final action taken to complete gowning. On the front of the gown are two ties, which require assistance to be tied to complete the gowning process. Disposable gowns have a paper tag attached to the ties, which can be handed to either a sterile or unsterile colleague. Having handed over the tag, the scrubbed person turns around and reclaims the tie, subsequently tying both ties together. If an unsterile colleague has assisted, care must be taken not to touch the paper tag she or he has handled. Reusable gowns do not usually have a sterile tag and the safest method of turning the gown is to hand the right hand tie to another scrubbed person and then complete the turn. The effect of this manoeuvre is to close the back panel of the sterile gown. It does not mean the back is sterile, but provides all-round protection to the wearer. Once gowned and gloved, the areas considered sterile are from the tips of the fingers to the elbows and from nipple to waist. It is acknowledged that these are arbitrary boundaries (Hamlin, 2008).

Assisted (open) gloving

Assisted gloving is the method whereby one scrubbed person gloves another scrubbed person; this may occur should the wearer contaminate a glove intraoperatively. Closed gloving cannot be achieved because the cuffs should not be pulled back over the hands as they are now unsterile. Therefore, the safest method of donning a replacement glove is for another sterile member of the team to assist with the gloving.

If both gown and gloves become contaminated, both must be removed and the donning procedure is carried out as previously described. Once gowned and gloved (Fig 5-10), the scrubbed person must stay close to the sterile field and not move out of the operating room into semi-restricted or unrestricted areas as this will increase the risk of cross-infection.

Figure 5-10 Nurse wearing sterile gown and gloves.

At the conclusion of the procedure, the surgical team must discard gowns, gloves and masks in contaminated waste containers within the operating room. This is done in a manner that ‘contains and confines’ contaminated items. For example, to avoid contamination of bare hands, the gown is removed first, rolled up so the inner surface is on the outside, and placed in the contaminated linen basket (if a reusable gown) or the contaminated waste bin (if a disposable gown). This is followed by the removal of the gloves. The hands should be washed following removal of the gown and gloves.

Strikethrough

Gowns and drapes act as barriers to prevent the transmission of microorganisms from non-sterile to sterile areas. If moisture penetrates the gowns or drapes, it permits the passage of microorganisms from a non-sterile surface to a sterile surface; this is termed ‘strikethrough’. The ability to prevent strikethrough is a critical factor in maintaining a sterile field and is achieved by the use of waterproof drapes and gowns (or by the use of plastic aprons under gowns made of permeable material). However, if strikethrough occurs on either gown or drapes, they must be replaced (NSW Health, 2007b).

On completion of the surgical procedure and following the application of a wound dressing, the drapes are removed immediately using a ‘contain and confine’ approach as described for the removal of gowns and gloves.

Inspection

Following mechanical washing and drying, all instruments are visually inspected by the trained sterilising department staff to ensure that there is no damage or defects and that the item is functioning correctly (i.e. scissors are sharp, the jaws of clamps are properly aligned). To sterilise an item that is not functioning correctly could place the patient at risk should it fail during surgery (Hurrell, 2005).

Assembly

Surgical instruments can be assembled in trays or be individually packaged. All operating suites will have a range of instrument trays to cater for the procedures they commonly perform (e.g. laparotomy, hysterectomy, orthopaedic trays). There will also be a general tray of instruments to which individual items may be added, depending on the procedure. All trays are standardised and will contain a specified number and type of instruments identified on a tray list, which is packaged and sterilised with the tray. The tray list is used for checking the contents preoperatively and postoperatively by the instrument and circulating nurses to ensure no items are inadvertently left inside the patient.

Packaging

The aim of packaging the instruments and equipment is to protect the sterilised items against contamination until they are opened ready for use in a surgical procedure. A variety of packaging materials are available and their choice depends on the item to be packaged and the sterilising process to be used. The packaging material must be:

Packaging materials can be reusable textiles (e.g. linen) or they can be specialised synthetic, single-use, spun bond polymer (Gruendemann & Mangum, 2001). Single-use, self-sealing pouches made of specialised paper or plastic have also been designed for individual items. Metal instruments, endoscopes and drills can be packaged in trays or containers that are made of moulded plastic or metal with perforations to allow penetration by the sterilising agent.

Once assembled, the tray/container is wrapped, usually in two layers of packaging material (this may vary depending on the material and local policy), and folded in a manner that allows subsequent opening using aseptic technique. A label identifying the tray is placed on the external surface. Depending on the sterilising agent to be used, the wrapping material will be sealed using a specialised indicator tape, which will change colour during the sterilising process. This becomes a visual check that the item has undergone the sterilisation process and is checked by the circulating nurse prior to opening the item. The change in colour of the external indicator tape alone does not guarantee sterility of the item. Other sterilising parameters must be met before sterility is assured and these are discussed below. However, if the indicator tape is found not to have changed colour, the item must be considered unsterile and not used.

Steam

Saturated steam under pressure is one of the most effective and commonly used methods of sterilisation. It is an inexpensive method and can be used on items capable of withstanding high temperatures (121–134°C), such as metal instruments and bowls. Steam sterilisation takes place in specially designed sterilisers, often called ‘autoclaves’, into which trays and individual items are carefully arranged to allow all surfaces to come into contact with the saturated steam. The autoclaves are preprogrammed to reach and maintain a specific temperature, pressure and time ratio depending on the type of load being sterilised (i.e. settings will differ for metal ware compared to linen or mixed loads).

The autoclave chamber is sealed and the sterilisation process begins with the creation of a vacuum inside the autoclave chamber, which is achieved by sucking out all the air. Following removal of all the air, steam under pressure is introduced into the chamber and the temperature will rise to the preprogrammed setting. This is known as the ‘penetration time’. When the required temperature and pressure is reached, the actual sterilisation of the items will begin. This is known as the ‘holding time’, which is approximately 15 minutes. When the holding time is completed, the steam is withdrawn and the load will be left to dry, using the residual heat in the metal walls. In the final stage of the process, filtered air is introduced, which returns the chamber to normal atmospheric pressure.

The steam sterilising process is designed to sterilise large loads of instruments within a central sterilising department, the end result of which is a wrapped, sterile item.

‘Flash’ sterilisation

A ‘flash’ steriliser is a smaller unit that uses steam but without the drying cycle of the models used in the central sterilising department. The cycle is rapid (hence the term ‘flash’), usually only several minutes, and the item emerges wet.

Flash sterilisers are designed for the management of single items. Operating rooms may have one or two flash sterilisers, permitting the sterilisation of reusable items for immediate use (Standards Australia, 2003, AS/NZS 4187). Their use is not endorsed for regular sterilisation due to their inability to dry items, which can easily become contaminated during subsequent transport to the operative field, which may be some distance away. Flash sterilisation is generally limited to use in emergencies for single items that may have been accidentally contaminated during surgery and for which a replacement cannot be located. The use of flash sterilisation demands adequate decontamination/cleaning of instruments, and daily performance monitoring of steriliser cycles to ensure efficacy of the sterilisation process (Standards Australia, 2003, AS/NZS 4187).

Dry heat

Dry heat sterilisation in the form of hot air ovens was once the only method by which powders, oils and glass could be sterilised. Today, these items are more likely to be supplied by commercial companies who use gamma radiation as a sterilisation method. This method is more economical as large volumes of the items can be sterilised. Dry heat is a slow, expensive method of sterilisation using a temperature range of 160–180°C, depending on the item and exposure time required (Gardner & Peel, 2001).

Ethylene oxide gas

Ethylene oxide (ETO) gas is a low-temperature (36–60°C) chemical method of sterilisation that is suitable for items that cannot be exposed to the high temperatures associated with steam or to dry heat. ETO is a highly toxic agent and exposure can cause severe toxic reactions, such as nausea, vomiting and respiratory difficulties, in health care workers. Therefore, strict occupational health and safety controls exist to protect operators of ETO sterilisers.

ETO is very effective in sterilising items such as rubber, silicone and polyethylene products, especially those with narrow lumens, and telescopes and drills. Items for sterilising are wrapped in single-use packaging or pouches and placed in an ETO steriliser, where the temperature and humidity are controlled before the ETO gas is introduced. The time taken to sterilise items can be up to 2 hours and, as ETO is absorbed into the items, there must be a further 2–12 hours’ aeration time to ensure that the ETO has been completely eliminated from the items before it can be used (Gruendemann & Mangum, 2001; Nicolette, 2007; Standards Australia, 2003, AS/NZS 4187).

Gas plasma

The gas plasma method uses hydrogen peroxide vapour and plasma to create a state under which items such as cameras, telescopes and drills can be sterilised under low-temperature conditions. This method has, in many instances, superseded ETO because it is a less toxic and more rapid form of sterilisation. Gas plasma involves the introduction of hydrogen peroxide vapour into a closed vacuum chamber through which radiofrequency waves are introduced, creating an electromagnetic field and conditions that kill microorganisms. The cycle time is approximately 30–60 minutes, depending on the model of steriliser, and the by-products are oxygen and water, thus making it substantially more environmentally sound than ETO (Nicolette, 2007).

Peracetic acid

Peracetic acid is a low-temperature, liquid chemical method of sterilisation that is suited for use with endoscopes that cannot be sterilised using high temperatures. Commercially produced processing systems are increasingly used within operating rooms where flexible endoscopes (e.g. gastroscopes) are used frequently and require sterilisation close to the time of use. The active ingredient is peracetic acid 35%, which is highly corrosive and, therefore, is used in combination with an anticorrosive agent. The processing unit is fully computerised and is the size of a small suitcase, with a lid and an internal tray especially configured to fit a flexible endoscope. A connection kit fits onto the exposed ends of the internal lumen system to ensure the sterilising agent passes through each lumen. Once the lid is closed and the processor activated, the active peracetic acid mixes with water and is fed over and through the endoscope for a period of 12 minutes, followed by four rinse cycles, which use filtered water to flush the peracetic acid away. The whole cycle takes approximately 30 minutes and the result is a wet, sterile scope ready for immediate use.

As with all items, thorough cleaning of the endoscope must occur prior to sterilisation, using specialised brushes and enzymatic cleaning agents to ensure that all lumens are free of debris and bioburden (Nicolette, 2007). The end product of peracetic acid is environmentally safe acetic acid and water.

Gamma radiation

Many commercially packaged products that are unsuitable for sterilisation by chemical or heat processes are sterilised by irradiation using the isotope cobalt-60, which produces gamma rays. Gamma rays can penetrate large cartons of items, making this an economical method for large medical companies to sterilise items such as ointments, sponges, plastic drapes and surgical gloves. This method is suitable for commercial application only.

Creutzfeldt-Jakob disease

The causative prions of CJD are highly resistant to conventional decontamination and sterilisation methods. Special protocols are required to manage instruments if they have been used on patients known or thought to be at risk of carrying the disease. Ideally, disposable instruments should be used, but this may not prove to be practical. Many institutions quarantine reusable instruments used on suspected CJD patients until test results from the patients have been obtained. Negative results will mean that routine decontamination and sterilisation processes can be followed. Positive results will require instruments to be reprocessed using combinations of germicidal solutions for mechanical cleaning followed by steam sterilisation at temperatures and pressures in excess of those routinely required for steam sterilisation (Nicolette, 2007). The management of equipment exposed to CJD prions is still evolving as further research is carried out on this highly infective, but fortunately rare, disease.

Physical

Regular maintenance, monitoring and testing takes place of all sterilisers to ensure that they are functioning correctly in accordance with Standards Australia (2003, AS/NZS 4187). All sterilisers have external gauges, thermometers, timers and computer printouts to monitor their functions. Internal sensors can provide information about temperature, pressure and humidity for every load. Documentation of these parameters is performed to provide permanent records so as to provide retrospective proof that all loads have passed through the sterilisation process satisfactorily.

Chemical

External indicators appear on the outside of each package and these change colour when the item has passed through a sterilisation process. These may be incorporated into the wrapping material, as in pouches, or as a separate tape or spots attached to the outside of the wrapped item. Different types of external indicators are required for each type of sterilisation method. The external indicators do not demonstrate that the item is sterile but do provide important visual indicators that the item has undergone a sterilising process.

An internal chemical indicator strip, known as an integrator, is placed inside with the items to assess the complete penetration of steam or chemical vapours. If the sterilisation parameters have been met, the strip will change colour, and this will be verified at the point of use by the instrument nurse prior to using the instruments. If the integrator strip has not changed colour, the items must not be used as sterilisation may not have occurred.

Biological

Biological indicators are standardised preparations of bacterial spores that are included as part of the routine testing processes of sterilisers to demonstrate whether sterilisation conditions have been met. Biological indicators are inoculated with a known concentration of spore preparations, which will be different, depending on the sterilisation process. For example, the spores used to test steam sterilisation conditions are those of Geobacillus stearothermophilis. Following exposure to the sterilisation process, the indicators will be examined to ascertain if the spores have been destroyed, which indicates that this testing parameter has been met.

No one testing parameter alone will verify that sterilisation conditions have been met. Sterilisation is achieved when all the physical, chemical and biological parameters have been met (Gardner & Peel, 2001; Standards Australia, 2003, AS/NZS 4187).

Tracking and traceability

The ability to track instruments and trace patients is an integral component of safety and risk management processes. Written and computerised records are maintained within the sterilising department to provide retrospective proof that an item has satisfactorily passed through a sterilisation process. These records are important should an outbreak of infection occur where investigations demonstrate that there may have been a breakdown in the sterilisation process. Patients who have undergone procedures during the period in question and may have been infected need to be traced and their infectious status investigated. Tracking systems rely on trays of instruments having barcodes and being scanned during decontamination and reprocessing, with the data stored on computer for future reference (Hurrell, 2005).

However, a more effective tracking system is one that is able to track an individual instrument back to a specific patient. Currently few such systems exist; however, with advances in technology, sophisticated instrument tracking systems will become more widespread in the future.