DETECTION OF PERSISTENT VEGETATIVE BACTERIA AND AMPLIFIED VIRAL NUCLEIC-ACID FROM IN-USE TESTING OF GASTROINTESTINAL ENDOSCOPES

Hospital-acquired infection attributed to inadequate decontamination o f gastrointestinal endoscopes prompted an in use evaluation of recomme nded procedures. Specimens were obtained from the internal channels of 123 endoscopes before, during and after decontamination by flushing w ith saline and brushing with a sterile brush, and examined for vegetat ive bacteria by broth and plate culture. Four endoscopy units were tes ted; the chemical disinfectants used were: 2% glutaraldehyde in Centre s 1 and 2 (automated) and Centre 3 (manual); peracetic acid in Centre 4 (automated). Samples from patients in Centre 1 with known chronic he patitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficie ncy virus (HIV-1) infection were also examined for viral nucleic acid by ultracentrifugation, nucleic acid extraction, reverse transcription (for RNA) and polymerase chain reaction (PCR). No persistent vegetati ve bacteria were found following standard manual cleaning and disinfec tion for 20 min in 2% glutaraldehyde in Centres 2 and 3 (N=37). At Cen tre 1, while plate culture yielded no growth, 34% of samples (10/29) g rew vegetative bacteria in broth culture after cleaning and disinfecti on for 20 min in 2% glutaraldehyde. Investigation revealed an error in manual cleaning; no bacteria were detected in 37 samples taken after this was corrected. At Centre 4, despite the use of peracetic acid as a sterilant, three out of 20 (15%) of post decontamination samples gre w bacteria; one contained persistent bacteria. HBV and HCV PCR analysi s detected viral nucleic acid in three out of four and four out of six samples from viraemic patients undergoing endoscopy in Centre 1 durin g the period of improper manual washing. After proper cleaning was ins tituted, samples from nine out of nine HCV viraemic patients were nega tive. HIV RNA was detected in five of 14 samples taken from endoscopes after use on HIV positive patients but all post decontamination sampl es were negative. Detection of bacteria in washes from endoscope chann els is a useful warning of a breakdown in decontamination practice. In adequate brushing of internal channels may result in persistent HCV an d HBV viral nucleic acid, the significance of which is not clear. Thes e results reinforce the importance of adequate manual cleaning of endo scopes before chemical disinfection.