In One Hospital, Pseudomonas Aeruginosa Serotype 10 Infected the Biliary

In one hospital, Pseudomonas aeruginosa serotype 10 infected the biliary tract of 10 percent of 1300 patients who underwent gastrointestinal endoscopic procedures. After each use, endoscopes were washed with an automatic reprocessor that flushed detergent and glutaraldehyde through the endoscopes, followed by a tap water rinse. P. aeruginosa serotype 10 was not isolated from the detergent, glutaraldehyde, or tap water. What was the source of the infections?

A) fecal contamination of the bile ducts
B) a biofilm in the reprocessor
C) bacterial cell walls in the water
D) contaminated disinfectant
E) None of the answers is correct.