Infection Control: 2019 Update
Keith F. Woeltje, M.D., Ph.D.
Dr. Woeltje is Professor of Medicine, Division of Infectious Disease, Washington University School of Medicine, St. Louis, MO.
Updated by E. Chandler Church, M.D., M.Sc. and Keith B. Armitage, M.D.
Dr. Church is a Resident, Department of Medicine, and Dr. Armitage is Professor of Medicine, Division of Infectious Diseases & HIV Medicine, University Hospitals Cleveland Medical Center and Case Western Reserve School of Medicine. Within the past 12 months, Drs. Church and Armitage have nothing to disclose relevant to this activity.
Albert Einstein College of Medicine, CCME staff and interMDnet staff have nothing to disclose relevant to this activity.
Release Date: 03/05/2019
Termination Date: 03/05/2022
Estimated time to complete: 1 hour(s).
Albert Einstein College of Medicine designates this enduring material for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
Albert Einstein College of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.
Learning ObjectivesUpon completion of this Cyberounds®, you should be able to:
Healthcare today has moved well beyond the walls of hospitals; outpatient infusion centers, ambulatory surgical centers and other professional facilities deliver care more complicated than was available in the best hospitals decades ago. Likewise, the term hospital-acquired infection (or "nosocomial infections") has yielded to the more general term "healthcare-associated infections" (HAI).
In the U.S., an infection develops in about 1 in 31 hospitalized patients, an estimated 1.2 million patients per year. Infections acquired during home care or from outpatient visits are less well documented but certainly occur. Competing factors are in play. More severely ill and more immunocompromised patients are in hospitals today, particularly with the increases in organ transplant; these patients are at increased risk for HAI. On the other hand, knowledge of how to prevent HAI is steadily improving and attitudes toward HAI are changing. CDC surveys demonstrated a decreased risk of HAI by 16% between 2011 and 2015. (1)
The vast majority of HAI can be prevented.
In the past, HAI were simply assumed to be an inevitable outcome in some fraction of patients — essentially a cost of doing business. But as many hospitals have driven rates of HAI steadily downward, we recognize that the vast majority of HAI can be prevented. Until we can prevent all infections in all settings, we may never reach zero for HAI. But already in many medical centers rates of some HAI, such as central line-associated bloodstream infections (CLABSI) and ventilator-associated pneumonia (VAP), are very close to zero, well below what many thought was possible.
Healthcare providers should recognize that HAI are not necessarily inevitable and they should be diligent in implementing measures known to prevent HAI. To reflect this, at many healthcare facilities the preferred term is shifting away from "Infection Control" to "Infection Prevention and Control," or even simply "Infection Prevention," to underscore that prevention of HAI is the primary goal.
A healthcare-associated infection is any infection that a patient develops during or as a result of their interactions with the healthcare community. For hospitalized patients this includes any infection that was not present or incubating at the time of admission (or if present on admission was the result of a previous hospitalization). For most infections it is assumed that infections that are manifest before 48 hours were community-acquired, whereas those that develop after 48 hours were the result of the hospitalization. For infections with long incubation periods, these time periods are adjusted accordingly.
Although patients may develop any kind of infection while hospitalized, the resources needed to track all nosocomial infections would be vast. Thus most healthcare facilities do not conduct comprehensive surveillance (also called "whole house surveillance") for all nosocomial infections. Rather, infection prevention and control programs focus on selected infections. These are typically chosen because they lead to significant patient morbidity or mortality, involve a large number of patients or are particularly expensive for the facility (or any combination of these factors). Also, higher priority is given to HAIs for which there are proven preventive interventions. Essentially all U.S. hospitals perform some HAI surveillance, as do many (if not most) outpatient surgical centers. Other ambulatory centers may not. In some states, surveillance for particular HAIs may be mandated by law and may be required to be reported to state authorities. In turn, these HAI rates may be reported to the public.
In order to conduct meaningful surveillance, it is imperative that a reasonable definition for the HAI of interest be developed, and that the definition be applied rigorously and consistently. The United States Centers for Disease Control and Prevention (CDC) developed definitions for HAI for use by its National Nosocomial Infection Surveillance System (NNIS), which is now known as the National Healthcare Safety Network (NHSN). NNIS/NHSN is a network of over 200 hospitals around the U.S. that utilizes these HAI definitions and reports their rates back to the CDC. The CDC NHSN then periodically publishes the aggregated results.(2)This report is the most comprehensive overview of HAI rates available. In order for a hospital to meaningfully compare its HAI rates with the NHSN data, the hospital would have to use the same definitions. Because the NHSN rates represent an excellent benchmark, the NHSN definitions have become the "gold standard" for use when performing HAI surveillance.
It is important to keep clear the distinction between a clinical definition of infection and a surveillance definition of infection. Practicing clinicians recognize that determining whether a patient has an infection can often be extraordinarily challenging. A wide variety of factors play into the decision to treat the patient for an infection, and in many cases the decision is made to treat the patient for a possible infection, even if it is unclear whether an infection is in fact present or not, because the consequences of delayed treatment may be too high. By contrast, the purpose of a surveillance definition is consistency — both over time and between institutions. This means that surveillance definitions try to be as non-ambiguous as possible. Thus, there may be patients who most clinicians would believe had an infection but who do not meet the surveillance definition and are, therefore, not counted as an HAI. This might occur if a patient develops fever and leukocytosis in the hospital setting, but no pathogen is identified.
The converse is true as well — a patient may meet the definition despite a clinician not believing that the patient had an infection. Although the definitions are designed to minimize such discordant results, for surveillance purposes the most important factor is that definitions be applied consistently. This is the only way in which rates can then be compared over time or between facilities.
Determining whether a patient has an infection can often be extraordinarily challenging.
Invasive devices are a mainstay of modern medical care. While lifesaving, they also significantly increase the risk of infection. Hospitals typically perform surveillance for device-associated infections in patients who are in intensive care units (ICUs). Device utilization is high in ICUs and the patients may be at higher risk for infection because of greater severity of illness. Central line-associated bloodstream infections (CLABSI) and ventilator-associated pneumonias (VAP) are most commonly followed. At some hospitals, catheter-associated urinary tract infections (CAUTI) are also followed.
Device-associated infection rates are typically reported as infections per 1,000 device days (typically calculated on a per month basis). This is calculated as:
# infections / # device days X 1000
The number of infections is determined during surveillance, typically by an infection control practitioner (ICP). A device day is a day in which a patient had a given device present. For venous catheters, even if more than one catheter is present in a patient during the day, it still only counts as one device day. Reporting rates normalized by device days allows rates between ICUs, or rates in the same ICU over time, to be compared, because it corrects for how often the device is utilized. Since different populations have different risk factors, NHSN reports CLABSI, VAP and CAUTI rates separately by type of ICU. This allows for a fairer comparison of these rates.
Surgical Site Infections
In addition to device-associated infections, most hospitals and surgical centers perform surveillance for surgical site infections (SSI). Typically, the volume of surgeries is such that all patients cannot be followed to determine whether they subsequently develop an SSI and surveillance is done only on selected surgeries. The focus is on high volume procedures or procedures in which an infection has a very high impact. Coronary-artery bypass graft surgeries (CABGs) and hip and knee joint replacements are examples of surgeries commonly followed.
The CDC NHSN has reported benchmark rates for 44 surgical procedures (or groups of procedures) as of October 2004. Because different patients have different risks of developing an infection, NHSN attempts to stratify patients into risk categories. Rates are reported separately for each risk category. This potentially allows institutions that tend to operate on sicker, higher risk patients to more readily compare their rates with a similar patient population.(3)Several newer models are adding additional variables, specifically age, to refine this model, although there is not yet a new model in consistent use.(4)
Currently, the CDC NHSN risk categories are determined by a 4-point scale, ranging from 0-3. A patient gets 1 point for each criterion that they meet: American Society of Anesthesiologists (ASA) score of 3 or more; surgical wound class of "contaminated" or "dirty;" and a duration of surgery >75th percentile for that procedure. Having a laparoscopic procedure, with its lower risk of infection, subtracts one point from a patient's score. Rates of SSIs are reported as the number of infections per 100 surgeries.
Surveillance for SSI typically starts with lists of patients who have had a procedure that is being followed. ICPs can screen the charts of such patients to see if they had fever, had a culture taken, were prescribed antibiotics or demonstrated some other indicator of infection. If so, a more detailed review of the chart would determine if the patient had an SSI based on the definitions.
Most SSIs, however, are detected only after the patient has returned home. Various strategies have been used to ensure that such SSIs are not missed. At a minimum, patients who have been readmitted to the hospital can be evaluated to ensure that an SSI wasn't the reason for their return. Outpatient microbiology laboratory data may also suggest that a patient has an infection. At some hospitals, surgeons are sent a list of patients so they can indicate whether the patient had developed an SSI. Other approaches to detecting SSIs in patients who are not readmitted to the hospital include calling the patient directly and reviewing the patients' outpatient medical records. Because surgeons and patients may not apply the strict definition of SSI consistently and because patient outpatient records are often unavailable to the hospital ICP, surveillance for SSIs in patients who do not return to the hospital remains problematic.
Most SSIs are detected only after the patient has returned home.
Good hand hygiene is considered to be the single most important intervention for reducing the rates of HAI. Ignaz Semmelweis demonstrated in 1846 at the Allegemeines Krankenhaus in Vienna that handwashing led to a dramatic drop in puerperal sepsis. Although physicians of that day were slow to believe that their hands could spread disease, with the development of the germ theory later in the 19th century the importance of clean hands in healthcare became well established. Unfortunately, despite the clear intellectual understanding of the need for good handwashing, the reality is that 17 decades later, healthcare providers are not very good at washing their hands.
Except in certain areas (such as operating rooms, where 100% compliance is the norm), several surveys report that healthcare workers only washed their hands ~40% of the time they should have.(5) With the introduction of alcohol hand-rub products, a broader term "hand hygiene" has been introduced to cover both traditional handwashing with soap and water as well as hand disinfection with an alcohol-based product. Because alcohol hand-rub dispensers can be placed in many more locations than sinks, they make it much more likely that healthcare workers will actually perform hand hygiene. Most alcohol-based hand-rubs contain hand emollients and are less likely to dry the skin than soap and water. In addition, alcohol-based hand-rubs take far less time than traditional soap-and-water washing. Table 1 shows the CDC-recommended indications for hand hygiene.(6) Handwashing with soap and water should be done whenever the hands are visibly soiled. Otherwise, use of an alcohol-based product for hand hygiene is acceptable. Both the CDC and the World Health Organization have made improved hand hygiene a major goal.
Table 1. Indications for Hand Hygiene.
Various interventions are recommended to prevent the spread of pathogens in the healthcare setting.(7) These precautions should be followed for all patients, regardless of any other infection control considerations. Good hand hygiene, of course, is the mainstay of standard precautions. In addition, gloves (non-sterile) should be worn whenever contact with any non-intact skin or bodily fluid is anticipated. A gown should be worn whenever splashing with blood or bodily fluids may occur. Likewise, a mask and proper eye protection should be worn whenever there is the possibility of being splashed in the face with blood or body fluids. Personal protective equipment should be removed and disposed of before leaving the patient's room so that common areas are not inadvertently contaminated.
Standard precautions cannot prevent the spread of all pathogens. For certain diseases, additional precautions are necessary depending on the route of spread.(7) Physicians should have a low threshold for instituting precautions early to prevent inadvertent exposures — precautions can always be discontinued later if proven to be unnecessary. For patients who are truly infected, isolation can be discontinued once they are no longer contagious — the hospital's Infection Prevention and Control Department should be contacted for specific details.
These precautions are indicated for patients who are known or suspected to have an illness disseminated by large respiratory droplets such as N. meningitidis RSV, or influenza. Because the infectious particles are not suspended in the air for long periods, special air handling is not necessary. A surgical mask (one that must be tied behind the head) or isolation mask (a simple paper mask with elastic ear hooks or a head strap that doesn't need to be tied) is considered to be sufficient respiratory protection from these illnesses. Masks should be worn upon entering a patient's room.
Because the infectious particles in diseases that are airborne spread can remain suspended in air currents for long periods of time and can travel long distances, special air handling is required for patients with airborne spread infections. These patients must be isolated in airborne infection isolation rooms (AIIR, also called negative-pressure ventilation rooms). Air pressure in these rooms is at a lower pressure than the air in the adjacent hallway. Thus, air comes in from the hallway, moves through the room and then is removed. For diseases where there is natural or vaccine-acquired immunity (e.g., varicella or measles), all workers should follow recommended airborne precautions detailed below, and non-immune workers should avoid contact when possible. Healthcare workers who are immune do not usually need any additional respiratory precautions to enter the AIIR (although this is not well studied and some institutions require respirator use to enter an AIIR at all times). Non-immune workers should not enter the room; in an emergency, they could use the procedure noted next for diseases where there is no immunity.
Standard precautions cannot prevent the spread of all pathogens.
For tuberculosis or other diseases where there is no immunity, some form of personal respiratory protection is required. At a minimum, a respirator (grade of N-95 or better) is recommended for entering the room. Higher ranked respirators, such as HEPA or positive-air-pressure respirators (PAPRs), may also be used in some settings. In the U.S., hospitals must have a fit-testing program to ensure that the N-95 (or other) respirator fits properly and that the healthcare worker knows how to use it correctly.
It is imperative that patients who are even suspected of having TB, chicken pox or measles be placed in airborne precautions promptly. Although this will lead to a certain amount of over-isolation, that is far preferable to having many patients and healthcare workers infected because no one thought of isolation or because it seemed like too much trouble. As with droplet precautions, hospital infection control departments have specific requirements that should be met before discontinuing airborne precautions.
Contact precautions are indicated for patients infected or colonized with organisms that are spread primarily via the hands of healthcare workers, or via contact with contaminated surfaces (e.g., hospital bedrail, blood-pressure cuff). While many organisms can spread via a "contact" mechanism, contact precautions are reserved for organisms that are either multiply drug resistant [e.g., methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE)], very problematic in the healthcare setting (e.g., varicella zoster) or both [e.g., Clostridium difficile (C. diff)]. Healthcare workers should don non-sterile gowns and gloves before entering the room of a patient on contact precautions. After patient care activities have been completed, the gown and gloves are removed immediately prior to the healthcare worker leaving the room, and hand hygiene is performed on room exit.
Gown and gloves should be put on prior to every entry into the room because it can be difficult for a healthcare worker to accurately predict whether they will have contact with the patient or the patient's environment. A healthcare worker may enter with the intention of only talking with the patient but may end up having to have to move a bedside table or check on an IV. At least one well-designed study has shown that use of both gown and gloves is superior to using gloves alone in preventing the spread of resistant organisms.(8)
A major misconception regarding contact precautions revolves around infection versus colonization. For some organisms, such as MRSA and VRE, prolonged colonization with asymptomatic carriage is not uncommon. Consider a patient with a MRSA bloodstream infection. It is extraordinarily unlikely that a healthcare worker will carry MRSA to another patient because they had infected blood on their hands. But the patient is likely to be colonized with MRSA. Staphylococcus aureus [both methicillin-sensitive (MSSA) and methicillin-resistant] primarily colonizes the anterior nares but can also colonize the axilla, groin and non-intact skin. MRSA or MSSA may also cause prolonged colonization of the respiratory tract in patients with a compromised clearance mechanism (e.g., a tracheostomy, cystic fibrosis). Staph may then transiently colonize other parts of the body. Thus, even after an active MRSA infection has resolved, a colonized patient may serve as a significant reservoir for MRSA. Whether the patient has an active infection is really incidental to the infection control issues in this setting — colonization is the major risk factor for the spread of an organism to other patients.
Contact precautions can be discontinued once the patient is no longer a significant potential source of spread. Hospitals have different policies regarding when contact precautions can be discontinued. For some organisms, it is once clinical disease has resolved (e.g., for VZV). For organisms that can have a prolonged asymptomatic carrier state, it may be necessary to obtain multiple cultures over a period of time while the patient is off effective antimicrobials, in order to verify that they are no longer colonized with the organism and thus no longer serve as a potential reservoir for spread to other patients.
It should be noted that there exists a specific category of “contact plus" precautions, generally applied to C. diff and other infectious diarrheas. In addition to the standard gown and gloves of normal contact precautions, all healthcare professionals are required to use soap and water for hand hygiene as opposed to alcohol-based hand sanitizers. This precaution should be in place for an infection with a spore-forming phase that may prove resistant to alcohol-based sanitizers.
A colonized patient may serve as a significant reservoir for MRSA.
Multi-drug resistant organisms (MDROs) have become an increasingly vexing problem in American hospitals. MDROs include MRSA, VRE, C. diff and multi-drug resistant gram-negative rods (MDR-GNR). Overall, MRSA makes up approximately 45% of S. aureus infections in the acute care setting; encouragingly, rates of hospital-acquired MRSA have shown a steady decrease since 2005.(9) However, multi-drug resistance in gram-negative rods showed a steady increase.(10)
Several studies indicate that patients with MDRO infections are less likely to receive appropriate initial empiric antibiotic therapy and this may lead to increased mortality. Other studies indicate increased hospital costs and increased lengths of stay for patients with MDRO infections.(11) In addition, few new antibiotics are on the horizon, although the advent of novel beta-lactamase inhibitor combinations has improved treatment options. Even with these new options, as MDROs become increasingly resistant, there may be no effective antimicrobials to use on patients infected with these organisms. Already some hospitals are seeing increasing numbers of infections with Acinetobacter resistant to all available antibiotics.(12) It is, therefore, imperative that infections with these organisms be prevented in the first place by preventing their spread.
The mainstay of preventing the spread of MDROs is effective use of contact precautions, as discussed above. Contact precautions cannot work, of course, if they are not implemented. Hospitals should have procedures in place to ensure that contact precautions are instituted promptly once a patient is found to be colonized or infected with an MDRO. This may entail the microbiology lab alerting the patient's nurse so that precautions can be instituted. It may also involve providing the infection control department with a list of all positive cultures with MDROs so that the ICP can double-check that the patients have indeed been placed in contact precautions. Measures should be in place to ensure that precautions are not discontinued without verifying with infection control that the patient is, in fact, clear of the MDRO.
Because prolonged carriage is possible with some MDROs, such as MRSA and VRE, many hospitals have a mechanism to "flag" the patient in the computerized registration system, so that if the patient is readmitted they are automatically placed in contact precautions. Such a system helps minimize the risk that a colonized patient will not be isolated and thus serve as a reservoir for spread of an MDRO to other patients. Admitting staff and nurses should be trained to look for such a flag on every admission to ensure that it is not overlooked.
Despite the common practices in most U.S. hospitals of contact precautions and flagging of patients, the prevalence of MDROs has steadily increased. This may result, in part, from poor adherence to contact precautions, standard precautions and hand hygiene on the part of healthcare workers. Nevertheless, traditional efforts have not proven to be entirely effective. For this reason, a number of organizations have called for more aggressive measures to stop the spread of MDROs. The Society for Healthcare Epidemiology of America (SHEA) and the CDC's Healthcare Infection Control Practices Advisory Panel (HICPAC) have both endorsed the idea of active surveillance with screening cultures if MDROs continue to increase in a hospital despite implementation of the measures discussed above.(13) (14)
The rationale for screening cultures is that some patients may be colonized with MDROs but may never have a positive clinical culture. Even for patients who do have a positive culture done for clinical reasons, this culture may not have been initiated until well into their hospital stay. Such patients may serve as silent reservoirs for the ongoing spread of MDROs. By obtaining a screening culture on admission, these patients could be identified and isolated earlier. Active surveillance is most beneficial for organisms that tend to have a prolonged colonization state such as MRSA and VRE.
In particular, active surveillance for MRSA has become more common in many U.S. hospitals as a consequence of the previous rapid increase in the proportion of S. aureus infections from MRSA. Active surveillance may be carried out only in specific areas such as intensive care units. Centers may perform surveillance only on patients considered at "high risk;" however, this strategy may miss a substantial proportion of colonized individuals.(13) Some states, such as Illinois, have mandated active surveillance for MRSA in hospitals. For these active surveillance measures to be effective at controlling MRSA, they must be tied to stringent infection control practices, especially diligent adherence to contact precautions and hand hygiene.
Some states mandate active surveillance for MRSA in hospitals.
An unresolved issue is when, if ever, to attempt decolonization in patients with MRSA colonization. Many infectious diseases physicians will attempt a decolonization regimen in patients with recurrent MRSA infections. Such regimens typically include nasal mupiricin (to decolonize the anterior nares), with or without antimicrobial body washes (to decolonize other sites), with or without oral antibiotics. Other than in the setting of recurrent infection, decolonization is not generally recommended. In particular, decolonization of asymptomatically colonized patients is not routinely indicated.(15)(16)
While the use of any medical device that enters the body may be associated with an increased risk of infection, the device-associated infections that are most common, and that receive the most attention, are central line-associated bloodstream infections (CLABSI), ventilator-associated pneumonia (VAP) and catheter-associated urinary tract infections (CAUTI). The most certain measure to prevent a device-associated infection is to avoid the use of the device. The need for a device should be evaluated daily and the device discontinued as soon as it is no longer necessary.
Over 250,000 CLABSIs are estimated to occur each year in U.S. hospitals,(17)with an estimated attributable mortality of 10-15% and cost between $16,000 and $46,000 per episode. Rates of CLABSI in ICUs are roughly 0.8 infections per 1000 catheter days, with international rates reaching 4.1 per 1000 catheter days. Rates for CLABSI outside the ICU are similar.(1) Factors associated with increased risk of CLABSI include prolonged hospitalization before catheterization, prolonged duration of catheterization, internal jugular catheterization, femoral catheterization (in adults) and substandard catheter care (e.g., excess line breaks/day; reduced nurse-to-patient ratio). A number of interventions have been proven to reduce the risk of CLABSI — these are listed in Table 2. The use of maximal sterile barrier precautions during catheter placement means that the inserter should have a sterile gown and gloves on, as well as a surgical mask and hair-cover. Any assistant working in the sterile field should be similarly attired. The patient should be covered with a broad sterile drape that covers most, if not all, of the patient (including the head for subclavian and internal-jugular line insertions). Comprehensive programs to prevent CLABSI, including extensive education of healthcare workers,(18) have led to prolonged CLABSI rates of 0 in many ICUs.(1)
Table 2. Interventions to Reduce the Risk of CLABSI.
Ventilator-associated pneumonia (VAP) is primarily a problem of intensive care units or, occasionally, long-term acute care facilities. Rates in the U.S. range from 0.2-8.5 episodes of VAP per 1000 ventilator days, depending on the type of ICU. Attributable mortality is between 33-50% depending on the type of ICU. Table 3 lists recommendations for reducing the risk of VAP. Not all of the recommendations have been fully validated but they are, nevertheless, considered good practice.(19)(20)The top 10% of all U.S. ICUs reporting to NHSN have a VAP rate of zero and for some ICU types the top 25% have a rate of zero. These results demonstrate what is possible with appropriate efforts.
Table 3. Interventions to Reduce the Risk of VAP.
CAUTI are the most common device-associated infection.
Catheter-associated urinary tract infections (CAUTI) are the most common device-associated infection. Although UTIs are often not seen as "serious" infections, they do increase patient morbidity, with concomitant increases in hospital length of stay and costs. NHSN reports rates in U.S. ICUs from 0.0-4.4 UTIs per 1000 urinary catheter days. In non-ICU medical-surgical units the rates reported by NHSN are 3.7 CAUTIs per 1000 catheter days, while on inpatient medical wards the rate is 7.1. Table 4 lists measures that can reduce the risk of a CAUTI. While proper catheter insertion and care techniques can reduce the risk, eventual development of a CAUTI is a near certainty if the urinary catheter is left in long enough. The primary focus in CAUTI reduction, then, is to ensure that urinary catheters are discontinued as soon as they are no longer medically necessary.(21)(22)
Table 4. Interventions to Reduce the Risk of CAUTI.
Surgical Site Infections
Surgical site infection (SSI) rates vary tremendously depending on the surgical procedure involved. For any given procedure, various factors including patient characteristics and the operating environment can significantly alter the risk of infection. While no one would argue against the pre-operative surgical scrub and sterile attire for those in the sterile field, many OR practices evolved over time, often without rigorous studies to confirm their use. Nevertheless, a number of operative factors have been clearly demonstrated to impact surgical site infection rates.(23) Clippers, rather than shaving, should be used to remove patient hair preoperatively if necessary. The use of razors has been associated with higher risk, presumably because microscopic skin nicks can provide a reservoir for bacterial pathogens.(24) Excessive traffic in the OR has been shown to increase the risk of an SSI. Crucially, surgical instruments must be properly cleaned and sterilized before use. The use of "flash" sterilization has also been associated with an increased risk of infection. This is not because an instrument that is properly flash sterilized is somehow less sterile; but, rather, the process of handling an instrument for flash sterilization provides more opportunities for contamination than routine cleaning and sterilization practices under less hurried and more controlled circumstances.
Most surgical site infections result from the introduction of the patient's own flora at the time of surgery. Provision of pre-operative antibiotics aimed at the most common causes of infection have led to significant reductions in surgical site infections. Since gram-positive infections predominate, cefazolin has become a common preoperative antibiotic for many procedures.(25) Cases involving the colon require broader spectrum coverage. In hospitals that have had a high rate of MRSA or methicillin-resistant coagulase negative staphylococcus infections, vancomycin may be considered for use rather than cefazolin for certain procedures such as cardiac surgery and prosthetic joint replacement.
For all preoperative prophylaxis, it is important to ensure that the patient has received the entire dose very shortly (within an hour) before the surgery begins — if given too late or too early, the patient will not derive the maximal benefit. Care must be taken to dose obese patients appropriately for their weight, so that adequate drug levels are achieved. In addition, for prolonged surgeries, antibiotics may need to be redosed in the OR (e.g., cefazolin should be redosed after 4 hours). Although commonly used, antibiotics given in the post-operative period have not been shown to reduce the risk of SSI. National guidelines for the appropriate choice of antibiotics have been published.(26)
To improve overall rates in the U.S., The Centers for Medicare and Medicaid Services (CMS) implemented a quality improvement project called the "Surgical Infection Prevention" (SIP) project in 2002. In 2003 additional agencies participated and SIP became SCIP — the Surgical Care Improvement Project. SIP and SCIP do not involve all procedures but do include abdominal hysterectomy, vaginal hysterectomy, knee arthroplasty, hip arthroplasty, cardiothoracic surgery, vascular surgery and colorectal surgery. Participation and reporting of at least some SCIP measures are necessary for hospitals to receive full Medicare reimbursement. The SCIP measures are largely evidence-based interventions that reflect accepted best practice for prevention of SSIs. Table 5 lists the current SCIP measures for SSIs.
Table 5. SCIP Measures for SSI.
Table 6. Additional Interventions to Reduce the Risk of SSIs.
Cases involving the colon require broader spectrum coverage.
Healthcare epidemiology and infection prevention are developing areas of expertise for physicians, nurses and allied health professionals. There is increasing evidence that with appropriate interventions, healthcare-associated infections are largely preventable. Increased public awareness and legislative efforts have helped spur healthcare institutions into action to implement such interventions. There is concern, however, that not all of the measures being called for by some consumer groups and legislative bodies are scientifically sound and that some of these efforts will divert resources from more effective interventions. Nevertheless, it is clear that all healthcare workers should have at least some knowledge of the basics regarding the detection and prevention of healthcare-associated infections, and, more importantly, should take steps to implement sound infection prevention measures in their own practices.
Lautenbach E, Woeltje K, editors. SHEA Practical Handbook for Healthcare Epidemiologists, 2nd Edition. Thorofare, NJ: SLACK, Inc.; 2004.
Society for Healthcare Epidemiology of America (SHEA) http://www.shea-online.org
Association of Professionals in Infection Control and Epidemiology http://www.apic.org
CDC Division of Healthcare Quality Promotion (DHQP) http://www.cdc.gov/ncidod/dhqp/index.html