Fifty Ways To Cause Surgical Site Infections

History of Prophylactic Antibiotic Use

Among the measures employed in prevention, none has received more attention than the use of preventive antibiotics. Following the introduction of sulfanilamide and penicillin into clinical practice after World War II, many surgeons believed and hoped that the millennium of infection-free surgery was soon to arrive; antibiotics would be given to surgical patients, bacteria would be killed, and infection would be thwarted. However, the promise of preventive antibiotics failed to be realized, and the late 1950s and 1960s ushered in a period of disillusionment about any benefits of antibiotics in the prevention of SSI.

However, experimental studies by Miles et al. [2] and the clinically applicable experimental model by Burke [3] gave new hope for the value of preventive antibiotics. These studies demonstrated that antibiotic activity against anticipated pathogens needed to be present in the tissue at the time of contamination of the surgical incision if infection was to be prevented. Bernard and Cole [4] performed a clinical trial with a suboptimal but nevertheless effective design, and Polk and Lopez-Mayor [5] completed a more rigorously stratified trial that demonstrated the effectiveness of antibiotics in the prevention of SSI in gastrointestinal and colon surgery. Stone et al. demonstrated that the initiation of antibiotics after wound closure was ineffective [6], and that prolonged post-operative administration did not add benefit to timely pre-operative administration [7]. Large numbers of randomized trials in virtually every setting of surgery have been completed subsequently, all documenting the value of pre-operative preventive antibiotics.

Even though the essential principles of antibiotic prophylaxis were disseminated widely, compliance in practice has been problematic, and continues to be. Timely pre-operative administration has been inconsistent, poor or undocumented drugs have been chosen, and surgeons still seem to be unwilling to discontinue antibiotics postoperatively. Compliance with accepted principles has been sufficiently suboptimal that some have recommended rigid policies be established to ensure compliance by hospitals [8].

In 2002, the Surgical Infection Prevention (SIP) Project was launched as a joint initiative by the U.S. Centers for Disease Control and Prevention (CDC) and the Centers for Medicare and Medicaid Services (CMS) to reduce SSI rates in the United States [9]. Representation from major surgical and infectious disease societies was convened, performance measures were drafted, appropriate antibiotic choices were defined, and publications were disseminated. Clinical samples of surgical cases were reviewed to underscore non-compliance with the drafted performance measures [10]. State-based collaboratives were organized in 2003 to disseminate relevant performance measures and appeared to show improvement in SSI outcomes with compliance [11].

The apparent success of the SIP project in the achievement of compliance with the three antibiotic-related performance measures led to an expanded Surgical Care Improvement Project (SCIP) [12–14]. In SCIP, the performance measures of appropriate pre-operative hair removal at the surgical site, glycemic control in cardiac procedures, and core temperature control for colon resections were added to the established antibiotic measures. Additional process measures were crafted for the prevention of venous thromboembolic disease, appropriate perioperative use of β-adrenergic blockade to prevent myocardial infarction, and some initial measures were proposed for the prevention of postoperative pneumonia. United States federal legislation required hospitals to report compliance with the performance measures [15]. Financial penalties were legislated against hospitals that failed to report their compliance. The extent of compliance is now posted on the www.hospitalcompare.gov website [16]. The stated objective of these performance measures and the legislative initiatives has been to reduce complications and cost by leveraging surgeons and hospitals to do the “right thing.”

Eight years have passed since the whole process has been started, and it is time for the “report card” on SCIP [14,17]. The assessment by Davis et al. [18] indicates that SSI rates may actually have increased during this interval. Others have reported similarly that compliance with SCIP performance measures has made no difference in SSI rates [17,19–21]. Many are asking why better compliance does not translate into better outcomes and whether the performance measures have any validity.

Definition and Surveillance of SSI

A fundamental problem in tracking and evaluating the rates of SSI over time is the lack of a standardized method for definition and surveillance. The CDC provided a series of reasonable definitions of SSIs (i.e., superficial incisional, deep incisional, or organ/space) [22]; however, adoption has not been universal (to wit, the continuing use of the inaccurate, indeed misleading, term “wound infection” in the literature). Moreover, the CDC definitions always end with the disclaimer that an infection exists if the surgeon declares that an infection exists. Similarly, an infection may not exist if the surgeon says that an infection does not exist. With the pressures for earlier discharge of hospitalized patients, it is likely that more infections are shifted from the inpatient to the outpatient setting, out of the purview of the hospital infection control authorities and never to be reported to anyone. The 30-day post-operative evaluation of the surgical site likely will not happen with any uniform completeness except in rigorous prospective studies. For example, recently, our group studied a four-year experience in elective colon surgery. In unreported results of that study [23], we found when using every conceivable International Classification of Diseases, Ninth Revision (ICD-9) code that SSIs occurred in 3.9% of all elective surgical cases. However, when rigorous surveillance at 30 days in carefully done studies is examined, the infection rate has been reported consistently to be above 20% for elective colon surgery [24–27]. The differences in rates may reflect different definitions or surveillance methods or both. It is impossible to measure the impact of performance measures at a population level without objective definitions and committed post-discharge surveillance. Inconsistent coding and variable intensity of surveillance create a difficult circumstance for the documentation of improvement or decline of SSI rates in a large population of patients from different hospitals. This inconsistency creates a major problem in the evaluation of SCIP.

Another consideration is whether we really care to know about every superficial discharge of turbid fluid or draining suture sinus from every incision. Surgical site infections occur across a vast continuum of severity. Our observations of hundreds of thousands of elective surgical cases indicate that more than 30% of coded SSIs are not associated with any increase in risk-adjusted length of hospital stay or in hospital cost. Should they be counted at all if there is no measurable clinical impact on morbidity or cost? This same logic applies to outpatient SSIs. Without readmission, emergency room visits, ambulatory drainage, or antibiotic administration, does transient discharge from the inferior aspect of a surgical incision following a Whipple resection really matter? Moreover, is the surgeon going to declare it an SSI if the event is to be reported in his or her clinical performance profile?

Clinical Parameters and SSI

Beginning with the classic Canadian studies of Cruse and Foord [28] to the present time [29], the number of patient co-morbidies and risk factors that have been associated with SSI are numerous. Table 1 lists my 50 favorites. There must be many more. A comprehensive risk equation that includes every patient co-morbidity and every clinical circumstance, and is also tailored to the unique features of each type of surgical intervention, would be extraordinarily complex. This constellation of variables means that compliance with SCIP performance measures can be cancelled out by poor surgical technique [30], excessive pre-operative length of stay [31], poor choice (or application) of surgical site preparation in the operating room [32], or combinations of any of a number of the parameters identified in Table 1.

Therefore, adherence to the details of surgical care may result in non-compliance with one or more process measures, yet the patient will have a favorable outcome nonetheless. The colon resection patient with a seven-day pre-operative hospitalization for legitimate reasons perhaps should receive a preventive antibiotic with a spectrum of gram-negative coverage that is greater than those endorsed by SCIP. The choice of a preoperative antibiotic with a long half-life may obviate dosing the patient within 60 min prior to the incision, even though SCIP would indicate (mandate?) otherwise. An orthopedic surgeon with excellent wound hemostasis and short operating times, working in an environment with excellent air handling and restricted traffic in the operating room, might pass on using preventive antibiotics altogether. Of course, he or she would be viewed as non-compliant, but still have excellent results. The SCIP has been a valiant and appropriate effort by CMS to provide process measures where “one size fits all.” It deserves our collective support, but SCIP is not a panacea for all the causes of SSI across the breadth of surgical care. It will not be feasible for a policy to cover all the interactive variables that can contribute to SSIs. Only well-trained, disciplined, and meticulous surgeons can address the many variables that cause or prevent SSI.

With due deference to Paul Simon and the mechanisms that can be employed in the dissolution of domestic relationships [33], there must be 50 ways to cause (and to prevent) SSI. Or, to quote Altemeier from 1958: “The evidence clearly indicates, however, that antibiotic therapy cannot be depended upon to prevent the development of local infection if established surgical principles or important technical details have been ignored” [34]. The SCIP has been a well thought-out and conscientious effort to provide well-documented performance measures to improve outcomes in surgical care. Its performance measures are contributors to better care but cannot be applied in a vacuum, and they can be totally over-ridden by suboptimal efforts in managing the large number of additional parameters that can end in SSI [17].

Whereas performance measures are a good start, measurement of outcomes must be the ultimate result of the surgical quality initiative. Frankly, the surgical community and our patients are interested in results, not “style points” for achieving a limited number of process measures. This is not synchronized swimming. Objective, reproducible, and clinically relevant outcomes must be the final measurement. Only then can we evaluate fully our progress in improving clinical quality.