Disinfection of equipment used for prostate biopsy

AORN Journal,  Sept, 2007  by George Allen

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Infection Control and Hospital Epidemiology

August 2007

A large number of invasive medical procedures, including approximately 46.5 million surgical procedures, are performed in the United States each year. Transrectal ultrasound (TRUS)-guided prostate biopsy is among the most common outpatient diagnostic procedures performed, with an estimated 624,000 procedures performed annually in the United States. A TRUS-guided prostate biopsy is performed to evaluate patients for prostate cancer, but a major risk in all such procedures is the introduction of pathogens that may lead to infection. Inadequate disinfection or failure to sterilize equipment carries a risk of infection as a result of residual microbial contamination.

In July 2005, four cases of Pseudomonas aeruginosa (P aeruginosa) infections were reported after TRUS-guided prostate biopsy. Contamination of the TRUS equipment likely resulted from tap water contamination of the probe and needle guide during inadequate rinsing and drying after high-level disinfection. The purpose of this study was to determine the effectiveness of the high-level disinfection process used for processing the equipment needed for TRUS-guided prostate biopsy.

Three sites on a probe used in TRUS-guided prostate biopsy, including

* the interior lumen of the biopsy needle guide,

* the interior lumen of the ultrasound probe where the needle guide passes through the transducer, and

* the outside surface of the biopsy needle guide,

were each inoculated on five or six occasions with 100 mcL of a solution containing 107 colony-forming units (cfu) of P aeruginosa. The inoculum was allowed to dry in a biological safety cabinet for 30 minutes.

After drying, the probe with the needle guide attached was submerged in a 2% glutaraldehyde solution for 20 minutes at 20[degrees]C (68[degrees]F). After 20 minutes of exposure to the glutaraldehyde, the probe was placed in sterile water for one minute, after which specimens from the inoculated sites were cultured. Tenfold serial dilutions were performed to assess the extent of microbial reduction, and 100 mcL of each dilution were plated onto sheep blood agar in duplicate, using the spread plate method.

In addition to the assessment of the assembled probe, the effectiveness of disinfecting

* the needle guide and transducer probe separately,

* the internal lumen of the ultrasound probe, and

* the inside and outside surfaces of the needle guide

also was assessed using the same methods. Common statistical procedures were used to analyze the data.

FINDINGS. The assembled probe achieved a reduction of only 1 [log.sub.10] cfu; consequently, it was determined that the assembled probe could not be effectively disinfected. When the needle guide was removed from the probe and disinfected separately, however, the result was complete inactivation of P aeruginosa organisms in the internal lumen of the ultrasound probe and on the inside and outside surfaces of the needle guide.

CLINICAL IMPLICATIONS. The results of this study demonstrated that a reduction in the bacterial load of greater than a 7 [log.sub.10] cfu can be achieved if the needle guide is removed from the probe before disinfection. Perioperative nurses should ensure that reprocessing with high-level disinfection solution is consistently performed. To appropriately reprocess TRUS-guided prostate biopsy equipment,

* the equipment should be cleaned immediately after use,

* the transducer should be disassembled,

* all lumens should be brushed clean and flushed with a detergent,

* the equipment should be rinsed with tap water and dried, and

* a visual inspection of the equipment should be performed.

Then high-level disinfection of the separated probe and needle guide should be performed and the equipment should be rinsed with sterile water, completely dried, and stored appropriately.

Rutala WA, Gergen MF, Weber DJ. Disinfection of a probe used in ultrasound-guided prostate biopsy. Infect Control Hosp Epidemiol. 2007;28(8):916-919.

GEORGE ALLEN

PHD, RN, CNOR, CIC

DIRECTOR OF INFECTION CONTROL

DOWNSTATE MEDICAL CENTER

BROOKLYN, NY

COPYRIGHT 2007 Association of Operating Room Nurses, Inc.
COPYRIGHT 2008 Gale, Cengage Learning