Research for infection protection

Microbiological surveillance of flexible endoscopes

Flexible endoscopes need to undergo microbiological testing at least once per year. For this, the German Association for Hospital Hygiene (DGKH) together with other associations has developed a procedure for both routine examinations and validation.


Under aseptic conditions (disposable clothing, hand disinfection prior to each sampling)
Two persons are required

1. Swab sample
2. Rinse sample

Sample processing
1. Check samples every 24 hours
2. Check sample after 44 hours (+ 4 hours) 

Test microorganisms
Enterobacteriacea, Pseudomonas aeruginosa, staphylococci, streptococci, faecal streptococci, mycobacteria, legionellae.

Growth media: the result of every single swab is evaluated. Microorganism growth on selective media = positive result per species.
Liquid samples: bacteria count. Result in CFU/ml of sample.

Evaluation result
Acceptable number of colonies = < 20 CFU per channel. The following microorganisms must not be present:
Escherichia coli, other enterobacteria, enterococci, Pseudomonas aeruginosa, other pseudomonads, nonfermenters, nosocomial pathogens such as Staphylococcus aureus, mycobacteria and legionellae, greening streptococci (acc. to risk analysis).

Growth of microorganisms and source of error, e.g.:
Detection of faecal microorganisms = deficient cleaning/disinfection
Detection of Pseudomonas aeruginosa, other pseudomonads and nonfermenters = insufficient water quality in final rinse

Deutsche Gesellschaft für Krankenhaushygiene (DGKH). Mitteilung des Vorstands.
Hygienisch-mikrobiologische Überprüfung flexibler Endoskope nach ihrer Aufbereitung.
Hyg Med 2010, 35(3):75-78. (available in German language)

Commission for Hospital Hygiene and Infection Prevention at the Robert Koch-Institute (RKI)
Hygiene Requirements for Reprocessing Flexible Endoscopes and Additional Endoscopic Instrumentation
Bundesgesundheitsbl Gesundheitsforsch Gesundheitsschutz 2002;45:395-411