title: Bacterial and viral contamination of breathing circuits after extended use - an aspect of patient safety?
abstract: BACKGROUND
  In the past, anaesthetic breathing circuits were identified as a source of pathogen transmission. It is still debated, whether breathing circuits combined with breathing system filters can be safely used for more than 1 day. The aim of this study was to evaluate the transmission risk of bacteria and also viruses via breathing circuits after extended use.
  
  
  METHODS
  The inner and outer surface of 102 breathing circuits used for 1 day and of 101 circuits used for 7 days were examined for bacteria and viruses. Additionally, 10 and 20 breathing circuits each were examined after use on patients with pulmonary virus infection and with multidrug-resistant organism (MDRO) colonisation/infection respectively. Bacteria were detected by standard microbiological procedures; PCR techniques were applied for herpes simplex virus, cytomegalovirus, influenza, parainfluenza and respiratory syncytial virus.
  
  
  RESULTS
  Endoluminal bacterial contamination of breathing circuits remained unchanged after 7-day vs. 1-day use (5.9% vs. 7.8%) [CI95%: -0.0886-0.0506, pnon-inferiority 0.0260]. Only outside surface contamination with bacteria belonging to environmental species or human flora increased (16.8 vs. 6.9%) [CI 95%: 0.0118 - 0.1876, pnon-inferiority 0.8660]. Viruses occurred on the patient side, but not in breathing circuits. No MDRO occurred in the 20 circuits after use on patients harbouring such germs.
  
  
  CONCLUSIONS
  Endoluminal contamination of breathing circuits with bacteria did not increase after extended use. No viruses were detected in the breathing circuits using filters. Based on our results, the extended use of ABC without exceptions appears safe, if a high level of anaesthesia workplace cleaning is secured.
authors.affiliation: Department of Anaesthesiology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Dubler
authors.affiliation: Department of Infectious Diseases, Medical Microbiology and Hygiene, Division Bacteriology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Zimmermann
authors.affiliation: Department of Infectious Diseases, Virology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Fischer
authors.affiliation: Department of Infectious Diseases, Virology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Schnitzler
authors.affiliation: Institute for Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Bruckner
authors.affiliation: Department of Anaesthesiology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: M A
authors.initials: MA
authors.lastname: Weigand
authors.affiliation: Department of Infectious Diseases, Medical Microbiology and Hygiene, Division Hospital and Environmental Hygiene, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Frank
authors.affiliation: Department of Anaesthesiology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Hofer
authors.affiliation: Department of Infectious Diseases, Medical Microbiology and Hygiene, Division Hospital and Environmental Hygiene, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Heininger
mesh_terms: D000776:Anesthesiology / Q000295:instrumentation*; D001419:Bacteria / Q000302:isolation & purification*; D004866:Equipment Contamination; D017743:Equipment Reuse; D006801:Humans; D061214:Patient Safety; D012121:Respiration, Artificial / Q000295:instrumentation*; D014780:Viruses / Q000302:isolation & purification*