The ERCP Patient: Risk Factors for Infection

Patient factors that contribute to infection risk: Increased Susceptibility to Infection

The immuno compromised patient is a patient who has defects in the body’s normal defense mechanisms that predisposes them to life-threatening infections that may not otherwise occur (18). Along with immune system diseases there are numerous patient factors that increase the risk of infection. Examples include cancer, transplant, age, pregnancy, occupation, residence, and travel/immigration status. Co-morbidities also contribute to infection risk. Examples include, but are not limited to, diabetes, eating disorder/poor nutritional status, drug/alcohol/tobacco addiction, chronic liver disease, and disease of the cardio pulmonary system (18). Those patient risk factors of most concern for ERCP patients are those with malignancies and liver transplant candidates/recipients (13, 19).

The risk of infection increases in patients with cancer due to two major concerns, the cancer itself and the effect of treatment. Treatment of malignancies may include use of cytotoxicchemotherapeutic drugs and/or radiation therapy which suppresses immune system function leading to a greater risk of infection (14). All cancer patients are fragile and therefore at risk, but all do not carry the same risk. Acute hematologic cancers are of greater concern than chronic because these patients are at increased risk of bacteremia and sepsis after endoscopy (19).

All transplant recipients are at greater risk for infection because they are receiving drugs that suppress the immune system (14). For the first 6-12 months after transplantation patients are at the highest risk of infection as anti-rejection drugs are given at their highest dosage during this time. For patients on a transplant waiting list, development of an infection may rapidly change their suitability for a transplant (20-22). Transplant candidates may be temporarily suspended from the list until the infection is resolved or can be delisted if the infection is caused by a multi drug-resistant organism (MDRO) or results in multiple organ failure (20-22). Infection is the primary cause for delisting a transplant candidate therefore, infection prevention is critical.

Patient factors that contribute to infection risk: Risk of Post-procedure Infection

Obstruction or stricture of a body passage is a recognized risk factor for infection (14). Cholangitis and sepsis are known adverse events associated with ERCP procedures occurring in up to 3% of cases (19). Incomplete biliary drainage was predictive of 91% of all cases of sepsis associated with ERCP (19). In those cases where complete drainage is not expected, a contaminated endoscope effectively “inoculates” the area with bacteria during the procedure further increasing the risk for infection (4).

Infection risk may be procedure related with an increased risk seen in those patients who have had select advanced, multiple, or concurrent procedures (2, 4, 13, 23, 24). Instrumentation and mechanical manipulation of tissues provides opportunities for the occurrence of transmission events (14). For example, biliary sphincterotomy is a risk factor for cholangitis (13). Placement of in-dwelling biliary stents to relieve obstruction from stones or malignancies increases the risk of infection. Biofilm formation on stents is also of concern as colonized stents provide a conduit for microbes to migrate to other ducts and tissues (13).

Patients who already meet criteria for receiving pre-ERCP antibiotic prophylaxis should be considered at higher risk for infection overall. The American Society for Gastrointestinal Endoscopy (ASGE) recommendations for antibiotic prophylaxis relevant to patients undergoing ERCP are summarized above (25). Of note is the recommendation for antibiotic prophylaxis to prevent infectious endocarditis (IE) in those patients with high-risk cardiac conditions that also have active GI infections such as cholangitis. ERCP patients may be especially vulnerable because of the high rate of post-procedure bacteremia (19).

Patient factors that contribute to infection risk: Risk of Post-procedure Infection

High-risk cardiac patients include those with a prosthetic valve, prior history of infectious endocarditis (IE), cardiac transplant recipients who develop valvulopathy, and patients with congenital heart disease (13). The prevalence of hospital-acquired IE may be increasing along with changes in the microbiology of the disease prompting a discussion on changing the strategies to prevent this disease (26).

Protection of Endoscope Inventory

Protection of Endoscope Inventory: Active Patient Infection and Colonization

Re-usable duodenoscopes (with or without removable end caps) exposed to patients with active infections are at risk of becoming persistently contaminated with pathogenic organisms and thus increasing the risk of patient infection and colonization (4). The emphasis on protection of a duodenoscope inventory has evolved as the GI community has become aware of pathogen transmissions and outbreaks associated with ERCP procedures (17). Currently the focus is on the emerging MDROs involved in these outbreaks but there should also be concern for infections caused by pan-sensitive pathogens with a less remarkable profile as they also result in significant patient morbidity and mortality (27). Active infections such as cholangitis, cholecystitis,localized infection, and septicemia all present risk for contamination of a duodenoscope inventory (2-4, 28). Patients colonized with pathogenic organisms are of concern because they may be asymptomatic or present with sub-clinical symptoms making them undetectable unless active screening is performed (14, 27, 29). Colonization also poses a risk to the patient as conversion to active infection may happen over a period of weeks to years (27). Travel history and immigration status may be an important factor as well as there are many regions of the world where MDROs are endemic (14).

Protection of Endoscope Inventory: Persistent Contamination of Endoscopes

Persistent contamination of a duodenoscope results from a complex interplay of events involving exposure to infected/colonized patients, ineffective reprocessing protocols, and complex duodenoscope design (2, 4, 17, 30). Despite best efforts to follow current reprocessing guidelines an endoscope that is known to be contaminated can remain contaminated despite multiple rounds of reprocessing (2, 4, 5, 16). Persistent contamination indicates that reprocessing is ineffective. The primary culprit that impedes effective reprocessing is the presence of biofilm which can be extremely difficult to remove even with adherence to best practice reprocessing protocols (6,7). The primary factors that contribute to persistent biofilm formation and microbial contamination are:

• Normal use of an endoscope results in damage that may include luminal shredding, scratches, gouges, staining, persistent debris, all of which provide a “safe harbor” for biofilm (1, 32, 33)
• Inadequate manual cleaning impedes high-level disinfection/sterilization (1)
  
• Incomplete drying resulting in storage of wet endoscopes (1,6, 34)
• Complex endoscope design impedes proper reprocessing (1).

Protection of Endoscope Inventory

Based on interim data from FDA post-market surveillance studies, up to 1 in 20 patient-ready duodenoscopes may be contaminated with pathogenic organisms (5, 31). Due to this ongoing challenge, contaminated duodenoscopes are now recognized as a risk factor for transmission of infection to ERCP patients (13).

Conclusion

A patient’s risk of developing an infection involves complex interactions involving patient factors, procedural factors, pathogen characteristics, and environmental factors (e.g. a contaminated duodenoscope) and therefore should be assessed on a case-by-case basis. Even though the infection rate associated with ERCP is considered low, the infections due to duodenoscope-associated transmissions and outbreaks are severe and life-threatening making infection prevention efforts critical to providing high quality patient care.