How Working Tasks Influence Biocontamination in an Animal Facility

Round 1

Reviewer 1 Report

The objective of this study was to determine factors (working tasks, changing cages frequency and animal strains) were associated with the greatest level of exposure to biological agents of the personnel working with rodents through the measure and characterization of airborne viable fungi, bacteria, endotoxin, (1,3)--Dglucan and animal allergens.. The study is relevant but some important data relating to the ventilation is not presented. I consider that the article must be completed before being accepted for publication.

The following comments shall be addressed:

1.       In the section 2 some details on the ventilation system of the rooms where the measurements were done are required (namely, the air flow rate, the inlets and outlets locations relating to the cages positions and relating to the sampling location).

2.       In the sections “2.2. Sampling and analysis of airborne bacteria and fungi” and “2.3. Inhalable dust sampling and analysis of endotoxin, (1,3)-β-D-glucan and allergens “ the uncertainty is not expressed. The uncertainty assessment results shall be presented.

3.       The information given in the section " 3.1. Airborne bacteria and fungi" is vague. The measurements where carried out in 7 different rooms with a variable number of animals and (maybe) a variable ventilation rate. The results must be presented by sampling room and should be compared with the variables differentiating every sampling room. The results in terms of average and standard deviation shall be presented.

4.       The information given in the section "  3.2. Endotoxin, (1,3)-β-D-glucan and allergens" must be completed. The measurements where carried out in 7 different animal rooms with a variable number of animals. The different workplaces may have  also a variable ventilation rate. The results must be presented by sampling room and should be compared with the variables differentiating every sampling room and workplace.

5.       In the section "3.3. Effect of the working activities" it is said that "the sampling during the changing cages was compared to the sampling before and after". The period of time between sampling must be indicated.

6.       Relating to the paragraph "Endotoxin concentrations, measured in this study, are higher than those reported by Hwang et al., 2016 [50] who found a mean value of 0.14 EU/m3 (range=0.03-0.60 EU/m3) in an animal laboratory housing mice, where the main tasks were feeding and weighing, and than those reported by Pacheco et al., 2006 [13] who measured a mean endotoxin concentration of 315 pg/m3 (about 3.15  EU/m3) with a peak value of 678 pg/m3 (corresponding about 6.78 EU/m3) during the changing cages in a mouse facility. Our data are also slightly higher than those reported by Ooms et al., 2008 [39] (mean value=4.7 EU/m3; range=3.4-6.3 EU/m3) in rabbit rooms but quite lower than those shown by Lieutier-Colas et al., 2001 [15] who found the highest concentration (15.4 ng/m3=154.7 EU/m3) associated with cage cleaning and feeding in animal rooms housing rats." of the section "4. Discussion" the concentrations in the indoor air will vary with the intensity of the sources and with the ventilation rate. This comparison should consider (when available) the number of animals and the ventilation rate of the sampling rooms.

7.       The section "5. Conclusions" is too generic. The most important findings should be referred to in this section. The text "Simple preventive measures such as the hands’ hygiene and the use of personal protective equipment must be adopted to control the biological risk. The workers should receive specific information about the risks deriving from exposure to biocontaminants during work and a specific training would be auspicable about the importance of the above mentioned preventive and control measures." is just referring to general knowledge that is not a direct conclusion from this work. I recommend the text to be simplified (e.g., just saying "Simple preventive measures must be adopted to control the biological risk.").

Author Response

Point 1: In the section 2 some details on the ventilation system of the rooms where the measurements were done are required (namely, the air flow rate, the inlets and outlets locations relating to the cages positions and relating to the sampling location).

 Response 1: details on the ventilation system have been added in the text.

Point 2: In the sections “2.2. Sampling and analysis of airborne bacteria and fungi” and “2.3. Inhalable dust sampling and analysis of endotoxin, (1,3)-β-D-glucan and allergens “ the uncertainty is not expressed. The uncertainty assessment results shall be presented.

 Response 2: a new table (Table 2) has been created to report the uncertainty assessment results.

Point 3: The information given in the section" 3.1. Airborne bacteria and fungi" is vague. The measurements where carried out in 7 different rooms with a variable number of animals and (maybe) a variable ventilation rate. The results must be presented by sampling room and should be compared with the variables differentiating every sampling room. The results in terms of average and standard deviation shall be presented.

 Response 3: The results of airborne bacteria and fungi in terms of average and standard deviation have been added in Table 3. Regarding animal rooms data are presented also by sampling room and the number of rodents is indicated. Although the ventilation rate was the same in these workplaces, as specified in the text, very different concentrations levels were found during the cage changing or before and after this procedure. This circumstance explains the very large dispersion of data and, consequently, the large value of the uncertainty.

Point 4: The information given in the section "3.2. Endotoxin, (1,3)-β-D-glucan and allergens" must be completed. The measurements were carried out in 7 different animal rooms with a variable number of animals. The different workplaces may have also a variable ventilation rate. The results must be presented by sampling room and should be compared with the variables differentiating every sampling room and workplace.

 Response 4: Also for endotoxin, (1,3)-β-D-glucan and allergens the results are presented by sampling room (see Table 3).

Point 5: In the section "3.3. Effect of the working activities" it is said that "the sampling during the changing cages was compared to the sampling before and after". The period of time between sampling must be indicated.

Response 5: air samples were taken over three consecutive days: the day of changing cages, the one before and the one after.

Point 6: Relating to the paragraph "Endotoxin concentrations, measured in this study, are higher than those reported by Hwang et al., 2016 [50] who found a mean value of 0.14 EU/m3 (range=0.03-0.60 EU/m3) in an animal laboratory housing mice, where the main tasks were feeding and weighing, and than those reported by Pacheco et al., 2006 [13] who measured a mean endotoxin concentration of 315 pg/m3 (about 3.15  EU/m3) with a peak value of 678 pg/m3 (corresponding about 6.78 EU/m3) during the changing cages in a mouse facility. Our data are also slightly higher than those reported by Ooms et al., 2008 [39] (mean value=4.7 EU/m3; range=3.4-6.3 EU/m3) in rabbit rooms but quite lower than those shown by Lieutier-Colas et al., 2001 [15] who found the highest concentration (15.4 ng/m3=154.7 EU/m3) associated with cage cleaning and feeding in animal rooms housing rats." of the section "4. Discussion" the concentrations in the indoor air will vary with the intensity of the sources and with the ventilation rate. This comparison should consider (when available) the number of animals and the ventilation rate of the sampling rooms.

Response 6: this part of “Discussion” has been deepened, when data were available.

 Point 7: The section "5. Conclusions" is too generic. The most important findings should be referred to in this section. The text "Simple preventive measures such as the hands’ hygiene and the use of personal protective equipment must be adopted to control the biological risk. The workers should receive specific information about the risks deriving from exposure to biocontaminants during work and a specific training would be auspicable about the importance of the above mentioned preventive and control measures." is just referring to general knowledge that is not a direct conclusion from this work. I recommend the text to be simplified (e.g., just saying "Simple preventive measures must be adopted to control the biological risk.").

Response 7: the last paragraph of the section 4 has been moved in the section 5 “Conclusions”.

The text "Simple preventive measures such as the hands’ hygiene and the use of personal protective equipment …..” has been simplified as suggested by the author.

Reviewer 2 Report

Manuscript no. applsci-506594

Title: How the working tasks influence the biocontamination in an animal facility.

The manuscript aims at determining factors which are associated with the exposure of biological agents of personnel working with rodents.

I found the Introduction section and the study design appropriate, as well as the Methods were adequately described. Conversely, the Results should be improved by the Authors.

In particular, I have minor suggestions, such as inserting a table reporting the statistical analysis results, in order to allow the readers to better understand the obtained findings.

Nevertheless, the manuscript is well organized and interesting, and I think that it would be well received by the readers. 

Other minor suggestions are:

line 79: please edit the formula.

lines 136 and 140: is "LLOD" abbreviation correct? Does it refer to the "LOD" one?

lines 291-293: please revise english.

Author Response

Point 1: Inserting a table reporting the statistical analysis results, in order to allow the readers to better understand the obtained findings.

Response 1: As regards the analysis, we reported the used statistical test and the results, in term of the test statistical significance, inside the text. Moreover, since different statistical tests have been used in order to answer to different hypothesis, we think that reporting the method and the statistical significance inside the text should be clearer for the reader.

Point 2: Line 79: please edit the formula.

Response 2: the formula has been edit.

Point 3: Lines 136 and 140: is "LLOD" abbreviation correct? Does it refer to the "LOD" one?

Response 3: the abbreviation correct is LOD; it has been modified in the text.

Point 4: Lines 291-293: please revise english

Response 4: the paragraph has been revised and inserted in the section 5 “Conclusions”, as requested by another reviewer.

Round 2

Reviewer 1 Report

No other comments.