Air microbial sampling in operating theatres by active and passive methods: equation correlation from the GISIO-ISChIA study results and comparison with the EU GGMP recommendation, towards the definition of threshold values Air microbial sampling in operating theatres: comparison between active and passive methods

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Cesira Isabella Maria Pasquarella
Francesco Auxilia
Martina Barchitta
Maria Luisa Cristina
Daniela D'Alessandro
Ida Mura
Marta Nobile
Licia Veronesi
Roberto Albertini
Antonella Agodi


operating theatres, microbial air contamination, active sampling, passive sampling, correlation


The aim of this study was to calculate the equation of correlation between the microbial air contamination values obtained by active sampling (colony-forming units per cubic metre, CFU/m3) and by passive sampling (Index of microbial air contamination, IMA), by using the data from the ISChIA study, and to compare the values obtained with the recommended limits defined by the EU Guidelines to Good Manufacturing Practice (EU GGMP), 2008, for clean areas used to manufacture sterile medicinal products.

Air sampling was performed during 335 elective prosthesis procedures. Correlation between CFU/m3 and IMA values was evaluated using the Spearman test; p<0.05 was considered to indicate significance. This equation was used to calculate the IMA values corresponding to the CFU/m3 recommended threshold values by EU GGMP for the different Grades of microbial contamination.

The following correlation equation was obtained: y = 1.86 + 0.12x, where “x” = cfu/m3 value and “y” = IMA value. The relationships between CFU/m3 and IMA values obtained from active and passive sampling during the ISChIA study showed to be in line to those suggested by the EU GGMP for pharmaceutical manufacturing for Grade C and D.

This study shows that the EU GGMP relationship could be considered valid also for operating theatres. Both methods, active and passive samplings, can be used to evaluate microbial air quality and highlight critical situations; however, in particular during the activity, passive sampling estimating the risk posed by airborne microorganisms to the surgical wound, can be considered more relevant, and for its simplicity, economy and standardization, can be suggested for routine microbial monitoring.



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1. Pasquarella C, Agodi A, Auxilia F, et al. Air quality in the operating theatre: a perspective. Aerobiologia 2020; 36:113-7. doi: 10.1007/s10453-019-09584-0.
2. ISO 14698‐1:2003. Cleanrooms and associated controlled environments - Biocontamination control - Part 1: General principles and methods.
3. UNI EN 17141: 2021 Cleanrooms and associated controlled environments - Biocontamination control.
4. Pasquarella C, Albertini R, Dall'Aglio P, Saccani E, Sansebastiano GE, Signorelli C. Air microbial sampling: the state of the art. Ig Sanita Pubbl 2008;64(1):79-120.
5. Pasquarella C, Pitzurra O, Savino A. The index of microbial air contamination. J Hosp Infect 2000;46(4):241-56. doi: 10.1053/jhin.2000.0820. PMID: 11170755.
6. Pitzurra M, Savino A, Pasquarella C. Microbiological environment monitoring (MEM). Ann Ig 1997;9(6):439-54.
7. Agodi A, Auxilia F, Barchitta M, Cristina ML, D'Alessandro D, Mura I, Nobile M, Pasquarella C; Italian Study Group of Hospital Hygiene. Operating theatre ventilation systems and microbial air contamination in total joint replacement surgery: results of the GISIO-ISChIA study. J Hosp Infect 2015;90(3):213-9. doi: 10.1016/j.jhin.2015.02.014.
8. Pasquarella C, M. Barchitta M, D’Alessandro D, et al. Heating, ventilation and air conditioning (HVAC) system, microbial air contamination and surgical site infection in hip and knee arthroplasties: the GISIO-SItI ISChIA study. Ann Ig 2018; 30 (Suppl. 2): 22-35. doi:10.7416/ai.2018.2248.
9. European Commission. EU Guidelines to Good Manufacturing Practice. Medicinal Products for Human and Veterinary Use. Annex 1. Manufacture of Sterile Medicinal Products. Brussels, 2008.
10. Arrowsmith LW. Air sampling in operating theatres. J Hosp Infect 1985;6(3):352-3.
11. Estates NHS. Health Technical Memorandum 03-01. Specialised ventilation for healthcare premises. Part A. Design and ventilation. Norwich: HMSO; 2007.
12. ISPESL. Linee Guida Sugli Standard di Sicurezza e di Igiene del Lavoro nel Reparto Operatorio. 2009.
13. Cristina ML, Spagnolo AM, Ottria G, Schinca E, Dupont C, Carbone A, Oliva M, Sartini M. Microbial Air Monitoring in Turbulent Airflow Operating Theatres: Is It Possible to Calculate and Hypothesize New Benchmarks for Microbial Air Load? Int J Environ Res Public Health 2021;18(19):10379. doi: 10.3390/ijerph181910379.
14. Pasquarella C, Vitali P, Saccani E, Manotti P, Boccuni C, Ugolotti M, Signorelli C, Mariotti F, Sansebastiano GE, Albertini R. Microbial air monitoring in operating theatres: experience at the University Hospital of Parma. J Hosp Infect 2012;81(1):50-7. doi: 10.1016/j.jhin.2012.01.007.

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