Etude n°49

• 49 . Hospital Admission Post Transrectal Ultrasound Guided Prostate Biopsy

La ponction de prostate sous échographie se déroule avec deux protections de sonde : une entre la sonde et le guide, l’autre par dessus le guide de biopsie. Deux patients sont infectés par E. Coli résistant peu après cet examen. La source 1ere de l’Infection n’a pas été trouvée mais le manque de désinfection du guide de biopsie est probablement la cause. Les recommandations ont été renforcée : le guide de biopsie doit être stérilisé et la sonde d’échographie doit subir une DNI.

Issue: Transrectal ultrasound (TRUS) guided prostate biopsy is a common outpatient procedure performed in the urology clinic to obtain biopsy samples under ultrasonic guidance. A transducer is covered with a condom, a steel needle guide is attached to it, and a second condom is applied. This is inserted into the rectum to visualize the prostate using ultrasound. A sterile disposable needle is inserted through the needle guide, through the rectal mucosa and into the prostate. Tissue is retrieved for biopsy and the needle is withdrawn through the needle guide. The same needle is reinserted through the needle guide for numerous biopsies. In October of 2007 Urology contacted Infection Control to report that two patients who had recently had TRUS guided prostate biopsies had been admitted to the medical center. Both patients had cultures that grew a resistant E. coli, one patient from blood and urine, the other from urine only. Antibiotic susceptibility testing (AST) patterns for the organisms were identical.

Project: Infection Control reviewed the procedure with the urology clinic staff. Review included equipment and instruments used, explanation of procedure, and methods for processing reusable instruments. Review of microbiology data going back to August did not yield additional isolates with matching AST in patients who recently underwent this procedure. The guide was cleaned with enzymatic detergent including brushing of the lumen with a small instrument brush. It was soaked in high level disinfectant which was not forced through the lumen. The transducer was wiped with a disinfectant cloth, and the needle gun was rinsed in tap water. The ultrasound gel comes non-sterile in a plastic squeeze bottle. Each provider used a different regimen for prophylaxis. Most included starting antibiotic prophylaxis 3 to 7 days prior to biopsy as well as continuing 3-7 days after. Infection Control made recommendations for cleaning, disinfection, and sterilization for all equipment and instruments used. These were disseminated to all urology clinics using the Situation, Background, Assessment, Recommendations (SBAR) format, and followed up with site visits to assess compliance. The issue of antibiotic prophylaxis was referred to the Infectious Disease Department for evaluation and recommendations.

Results: Eight needle guides were retrieved from the urology clinic and taken to the laboratory for culture. Broth was run through the lumens and plated on agar. There was difficulty running the broth through one of the needle guides. It wasn’t until after brushing the guide with a very fine wire that the broth ran through. The plate from this guide showed confluent growth. This isolate did not match the two patients’ isolates. There was no growth from the other guides.

Lessons Learned: Inadequate processing of the needle guide was the most likely cause of these two infections. If the broth used to culture the needle guides was not able to freely flow through the lumen, the high level disinfectant would not have been able to flow through either. The process used to clean and disinfect the needle guide and the rectal probe was not consistent with the internal policy or the manufacturer’s recommendations. Since the biopsy needle passes through the needle guide before penetrating sterile tissue, it is a critical device and should be sterilized. The rectal probe requires high level disinfection. The antibiotic prophylaxis regimens in use may have been selecting out resistant organisms. The organism that caused the infections was resistant to the antibiotics used for prophylaxis.