We thank Prof. Büttner-Janz for her contribution. As she rightly says, microbial load in partial results in our study was tendentially higher after septic procedures than after aseptic ones (1). Because of the wide spread and the very small deviations, we considered these differences to be irrelevant. Furthermore, the significantly larger proportion of aerobic spore forming bacteria affected the mean values of the microbial load in the procedure rooms. Etiologically, however, these pathogens are out of the question in terms of causing postoperative wound infections. For visceral surgical procedures, individual findings of E faecalis and E coli do not translate into a risk of infection, because these findings are far below any infectious dose. As the results were obtained in an operating room without a room ventilating system (RVS) and the recovery time in a setting of mixed air flow is a maximum of 20 minutes, with an RVS, pathogens still present in the room air will be eliminated by the start of the procedure. Even without an RVS and with a changeover time of 30 minutes, it is not necessary to separate operating areas.
The comment that „the fact that the differences between the 2 procedure types were statistically insignificant cannot […] be interpreted as direct evidence of equal microbial load“ was quoted in an abbreviated form. It relates only to the study design, which was originally not intended to be that of an equivalence or non-inferiority study.
The Geneva study, according to which 90% of infections after implantation of a joint endoprosthesis developed during the procedure, does not permit the conclusion that the pathogens came from the environmental air. Such infections are almost exclusively caused by Gram-positive pathogens in the skin microflora. In order to minimize this risk of infection, low-turbulence laminar flow is recommended (2), which serves to keep the operating field free from pathogens over the duration of the procedure (3).
Prof. Dr. med. Axel Kramer
Institute for Hygiene and Environmental Medicine, University Medicine Greifswald,
Dr. med. Julian-Camill Harnoss
Department of General, Visceral and Transplantation Surgery
and Study Center of the German Surgical Society
University of Heidelberg
Prof. Dr. phil. Thomas Kohlmann
Institute for Community Medicine, University Medicine Greifswald
Conflict of interest statement
The authors declare that no conflict of interest exists.
|1.||Harnoss JC, Assadian O, Diener MK, Müller T, Baguhl R, Dettenkofer M, Scheerer L, Kohlmann T, Heidecke CD, Gessner S, Büchler MW, Kramer A: Microbial load in septic and aseptic procedure rooms—results from a prospective, comparative observational study. Dtsch Arztebl Int 2017; 114: 465–72 VOLLTEXT|
|2.||Guilloteau A: Qualité de l’air au bloc opératoire et autres secteurs interventionnels. Hygiènes 2015; 23: 1–58.|
|3.||Erichsen Andersson A, Petzold M, Bergh I, Karlsson J, Eriksson BI, Nilsson K: Comparison between mixed and laminar airflow systems in operating rooms and the influence of human factors: experiences from a Swedish orthopedic center. Am J Infect Control 2014; 42: 665–9 CrossRef MEDLINE|