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Patient shoe covers: Transferring bacteria from the floor onto surgical bedsheets
ARTICLE IN PRESS American Journal of Infection Control ■■ (2016) ■■-■■
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
j o u r n a l h o m e p a g e : w w w. a j i c j o u r n a l . o r g
Brief report
Patient shoe covers: Transferring bacteria from the floor onto surgical bedsheets Justin Galvin BSc a, Ahmad Almatroudi MPH a, Karen Vickery PhD a, Anand Deva MBBS a, Lillian Kelly Oliveira Lopes MN a,b, Dayane de Melo Costa MN a,b, Honghua Hu PhD a,* a b
Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia Faculty of Nursing, Federal University of Goias, Goias, Brazil
Key Words: Shoe covers bedsheet bacteria transfer infection control surgical site infections
Forty disposable medical shoe covers were briefly exposed to the surgical floor and were found contaminated by a large number of bacteria. This study also demonstrated live bacteria, including pathogens attached to contaminated shoe covers, can be subsequently transferred to surgical bedsheets. We suggest an infection control policy should be considered to prevent patients returning to their bed with contaminated disposable shoe covers. © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Sanitation is of the utmost importance and is at the forefront of investigations into reducing infection in the operating theater. The hospital operating theater is considered to be aseptic because of the vigorous cleansing procedures, protective clothing, and sterile equipment implemented within the hospital environment. 1 However, bacteria, including multidrug-resistant organisms, such as methicillin-resistant Staphylococcus aureus2 and vancomycinresistant Enterococci,3 can survive for prolonged periods in the hospital environment in lieu of hygienic practices. Approximately one-third of all health care–associated infections are caused by surgical site infections (SSIs).4,5 SSI incur increased financial costs to both the patient and the hospital because of prolonged treatment time, patient readmission, and increased morbidity and mortality.6,7 The microorganisms prevalent in SSI are Staphylococcus spp, including sensitive and resistant S aureus and coagulasenegative Staphylococcus.5,8 Although SSI remains a burden on our society, preventative measures can be implemented for greater protection of our community. For example, although both the attire of health care workers and patients, including shoe covers, are used as barriers against the microorganism, it can also act as a vehicle of transfer to the surgical theater bed. Surprisingly, there is no well-documented relationship between the use of shoe covers by patients and the risk of developing SSI.1
We hypothesize that disposable shoe covers used by patients before surgery have the potential to contaminate the surgical table if not removed. However, to our knowledge, there is no removal of patient-contaminated shoe covers in infection control guidelines. The aim of this study is to investigate whether patient shoe covers can be a vehicle to transfer bacteria from the day surgery floor to surgical bedsheets. MATERIALS AND METHODS Clinical study A total of 40 disposable nonskid polypropylene medical shoe covers were worn outside 2 sterile plastic bags while walking in the day surgery unit in a teaching hospital in Sydney, Australia, on 5 separate days. Walk locations (and duration) consisted of the patient cubicle (5 and 10 minutes), bathroom (5 minutes), and corridor (5 minutes). The contaminated shoe cover was placed inside a sterile paper bag with a piece of sterile cotton-polyester bedsheet used in the hospitals and rubbed 20 times against each other. The quantity of bacteria and identification of bacterial species attached to the polypropylene shoe covers and subsequently transferred to the bedsheet were determined by standard plate culture, colony forming units (CFU), and 16s ribosomal RNA gene sequencing. In vitro laboratory study
* Address correspondence to Honghua Hu, PhD, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109. Australia. E-mail address: [email protected] (H. Hu). Conflicts of Interest: None to report.
Then 107 bacterial cells from each common pathogen S aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecium, and Acinetobacter baumannii were spread
0196-6553/© 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2016.03.020
ARTICLE IN PRESS J. Galvin et al. / American Journal of Infection Control ■■ (2016) ■■-■■
2
over sterile Petri dishes and air dried. Next, each piece of 2 different types of disposal medical shoe covers commonly used in hospitals (polypropylene and polyethylene) was laid on top of the dried bacteria and pressed down 10 times by a sterile spreader. Each contaminated shoe cover piece was subsequently placed on top of a piece of cotton-polyester bedsheet and pressed down across the shoe cover and bedsheet 10 times by a sterile spreader. The number of bacteria attached to shoe covers and rates of bacterial transmission from artificially contaminated shoe covers to bedsheets were determined for each bacterial species in triplicates.
RESULTS Clinical study Bacteria were found contaminating shoe covers, with an average of 226 CFU/cm2 at 5 minutes of walking in patient cubicle and 8,080 CFU/cm2 at 5 minutes of walking in the bathroom (Table 1). Some
Table 1 Number of bacterial colony forming units attached to a shoe cover and subsequently transferred to a hospital bedsheet
Walking location and duration Corridor (5 min) Bathroom (5 min) Patient cubicle (5 min) Patient cubicle (10 min)
Bacteria attached to shoe cover, cm2
Bacteria transferred to bedsheet, cm2
Bacterial transfer rate (shoe cover to bedsheet), %
1,854 ± 1,180 2,598 ± 3,176 226 ± 229
86 ± 170 34 ± 71 4±5
5.70 ± 6.58 0.48 ± 0.86 1.25 ± 2.80
1,074 ± 1,219
32 ± 40
1.12 ± 1.20
NOTE. Values are presented as mean ± SD.
Table 2 Bacterial genus identified on contaminated bedsheet transferred from shoe cover contacted with each floor location Original location Corridor
Bathroom
Patient cubicle
Bacterial genus
No. of samples
Staphylococcus spp Bacillus spp Micrococcus spp Brachybacterium spp Staphylococcus spp Escherichia coli Acinetobacter spp Staphylococcus spp Micrococcus spp
7 2 1 1 5 1 1 8 1
live bacteria from shoe covers were subsequently transferred to bedsheets with a transfer rate ranging from 0.5%-5.7% (Table 1). The day surgery corridor shoe covers yielded the highest transfer rates to the bedsheets. Staphylococcus spp were the principal bacteria transferred from contaminated shoe covers to bedsheets (Table 2).
Laboratory study From 107 bacteria spread and dried, the average live bacteria attached to each shoe cover piece ranged from 219-371 CFU. The transfer rate to the bedsheets for common pathogens ranged from 6.9%-15.1% for polypropylene and 7.5%-17.7% for polyethylene shoe covers. S aureus had the highest transfer rate, whereas P aeruginosa had the lowest transfer rate (Table 3).
DISCUSSION The hospital floors in the day surgery unit were cleaned daily and appeared clean by visual observation. Nevertheless, the shoe covers worn for 5 minutes picked up substantial amounts of live bacteria. This highlights the ability of microorganisms to be present in seemingly clean environments. This study also demonstrated that the live bacteria attached to contaminated disposable medical shoe covers can be subsequently transferred to bedsheets. This has the implication of all patients being equally susceptible to infection regardless of their waiting time prior to surgery, especially if they get into and out of their bed on multiple occasions. The transmission of bacteria from the day surgery floor to the bedsheet opens up the possibility of a patient developing an SSI. In the United States, S aureus accounts for most cases of hospitalacquired infections.9 Many bacteria isolated from contaminated bedsheets in this study were identified as Staphylococci genus (Table 2). The ease at which microorganisms can be transferred to the surgical bedsheets has implications for improved infection control to minimize the burdens of hospital-acquired infections. Mortality associated with SSI has risen dramatically over the last 20 years.6,7 Therefore, small steps toward improved infection control may add to large gains in the quality of patient care. In conclusion, we have demonstrated that disposable medical shoe covers can transmit bacteria, including pathogens, from the hospital floor to the surgical bedsheets, resulting in a potential risk for hospital-acquired infections. Infection control requires the minimization of risks to prevent patients developing hospital-acquired infections. Unfortunately, the use and removal of patient shoe covers are not dictated in infection control guidelines. 10 This study
Table 3 Number of bacterial colony forming units from 107 dried bacterial cells attached to one piece of shoe cover and subsequently transferred to hospital bedsheet
Bacterial species Staphylococcus aureus, ATCC 25923 Staphylococcus epidermidis, ATCC 35984 Enterococcus faecium, ATCC 35667 Acinetobacter baumannii, ATCC 19606 Pseudomonas aeruginosa, ATCC 25619 Escherichia coli, K12 C600 NOTE. Values are presented as mean ± SD. PE, Polyethylene; PP, Polypropylene.
Shoe cover material
No. of bacteria attached to shoe cover
No. of bacteria transferred to bedsheet
Bacterial transfer rate (shoe cover to bedsheet), %
PP PE PP PE PP PE PP PE PP PE PP PE
306 ± 22 371 ± 23 279 ± 39 296 ± 21 293 ± 25 346 ± 29 219 ± 33 259 ± 26 297 ± 28 319 ± 41 280 ± 47 312 ± 56
54 ± 4 81 ± 6 39 ± 5 50 ± 3 40 ± 5 54 ± 7 25 ± 4 33 ± 6 22 ± 4 26 ± 4 38 ± 11 45 ± 12
15.08 ± 0.66 17.74 ± 0.53 12.36 ± 0.39 14.53 ± 0.71 11.87 ± 0.92 13.47 ± 1.10 10.16 ± 0.35 11.15 ± 0.86 6.92 ± 0.50 7.51 ± 0.68 8.92 ± 1.23 11.07 ± 0.83
ARTICLE IN PRESS J. Galvin et al. / American Journal of Infection Control ■■ (2016) ■■-■■
demonstrates a potentially overlooked source of contamination and possible infection. We suggest an infection control policy should be considered to prevent patients returning to their bed with contaminated disposable shoe covers because this simple measure may reduce surgical bed contamination and the number of SSIs and their associated detrimental impact. Acknowledgments We would like to acknowledge the friendly Macquarie University Hospital staff for their support of this study. Lillian Kelly Oliveira Lopes was in receipt of CAPES Scholarship (process no. 99999.006360/2014-09). Dayane de Melo Costa was in receipt of Cotutelle iMQRES scholarship (allocation no. 2015142) and CAPES Scholarship (process no.99999.006361/2014-05). References 1. Eisen DB. Surgeon’s garb and infection control: what’s the evidence? J Am Acad Dermatol 2011;64:960, e1-20.
3
2. Cho OH, Baek EH, Bak MH, Suh YS, Park KH, Kim S, et al. The effect of targeted decolonization on methicillin-resistant Staphylococcus aureus colonization or infection in a surgical intensive care unit. Am J Infect Control 2016;44:533-8. 3. Wagenvoort JH, De Brauwer EI, Penders RJ, Willems RJ, Top J, Bonten MJ. Environmental survival of vancomycin-resistant Enterococcus faecium. J Hosp Infect 2011;77:282-3. 4. Magill SS, Hellinger W, Cohen J, Kay R, Bailey C, Boland B, et al. Prevalence of healthcare-associated infections in acute care hospitals in Jacksonville, Florida. Infect Control Hosp Epidemiol 2012;33:283-91. 5. Ott E, Saathoff S, Graf K, Schwab F, Chaberny IF. The prevalence of nosocomial and community acquired infections in a university hospital: an observational study. Dtsch Arztebl Int 2013;110:533-40. 6. Merkow RP, Ju MH, Chung JW, Hall BL, Cohen ME, Williams MV, et al. Underlying reasons associated with hospital readmission following surgery in the United States. JAMA 2015;313:483-95. 7. Urquhart DM, Hanna FS, Brennan SL, Wluka AE, Leder K, Cameron PA, et al. Incidence and risk factors for deep surgical site infection after primary total hip arthroplasty: a systematic review. J Arthroplasty 2010;25:1216-22, e1-3. 8. Ercole FF, Franco LM, Macieira TG, Wenceslau LC, de Resende HI, Chianca TC. Risk of surgical site infection in patients undergoing orthopedic surgery. Rev Lat Am Enfermagem 2011;19:1362-8. 9. Weigelt JA, Lipsky BA, Tabak YP, Derby KG, Kim M, Gupta V. Surgical site infections: causative pathogens and associated outcomes. Am J Infect Control 2010;38:112-20. 10. Centers for Disease Control and Prevention. Surgical site infection (SSI) event. 2016. Available from: http://www.cdc.gov/nhsn/PDFs/pscManual/9pscSSIcurrent .pdf. Accessed January 25, 2016.
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
j o u r n a l h o m e p a g e : w w w. a j i c j o u r n a l . o r g
Brief report
Patient shoe covers: Transferring bacteria from the floor onto surgical bedsheets Justin Galvin BSc a, Ahmad Almatroudi MPH a, Karen Vickery PhD a, Anand Deva MBBS a, Lillian Kelly Oliveira Lopes MN a,b, Dayane de Melo Costa MN a,b, Honghua Hu PhD a,* a b
Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia Faculty of Nursing, Federal University of Goias, Goias, Brazil
Key Words: Shoe covers bedsheet bacteria transfer infection control surgical site infections
Forty disposable medical shoe covers were briefly exposed to the surgical floor and were found contaminated by a large number of bacteria. This study also demonstrated live bacteria, including pathogens attached to contaminated shoe covers, can be subsequently transferred to surgical bedsheets. We suggest an infection control policy should be considered to prevent patients returning to their bed with contaminated disposable shoe covers. © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Sanitation is of the utmost importance and is at the forefront of investigations into reducing infection in the operating theater. The hospital operating theater is considered to be aseptic because of the vigorous cleansing procedures, protective clothing, and sterile equipment implemented within the hospital environment. 1 However, bacteria, including multidrug-resistant organisms, such as methicillin-resistant Staphylococcus aureus2 and vancomycinresistant Enterococci,3 can survive for prolonged periods in the hospital environment in lieu of hygienic practices. Approximately one-third of all health care–associated infections are caused by surgical site infections (SSIs).4,5 SSI incur increased financial costs to both the patient and the hospital because of prolonged treatment time, patient readmission, and increased morbidity and mortality.6,7 The microorganisms prevalent in SSI are Staphylococcus spp, including sensitive and resistant S aureus and coagulasenegative Staphylococcus.5,8 Although SSI remains a burden on our society, preventative measures can be implemented for greater protection of our community. For example, although both the attire of health care workers and patients, including shoe covers, are used as barriers against the microorganism, it can also act as a vehicle of transfer to the surgical theater bed. Surprisingly, there is no well-documented relationship between the use of shoe covers by patients and the risk of developing SSI.1
We hypothesize that disposable shoe covers used by patients before surgery have the potential to contaminate the surgical table if not removed. However, to our knowledge, there is no removal of patient-contaminated shoe covers in infection control guidelines. The aim of this study is to investigate whether patient shoe covers can be a vehicle to transfer bacteria from the day surgery floor to surgical bedsheets. MATERIALS AND METHODS Clinical study A total of 40 disposable nonskid polypropylene medical shoe covers were worn outside 2 sterile plastic bags while walking in the day surgery unit in a teaching hospital in Sydney, Australia, on 5 separate days. Walk locations (and duration) consisted of the patient cubicle (5 and 10 minutes), bathroom (5 minutes), and corridor (5 minutes). The contaminated shoe cover was placed inside a sterile paper bag with a piece of sterile cotton-polyester bedsheet used in the hospitals and rubbed 20 times against each other. The quantity of bacteria and identification of bacterial species attached to the polypropylene shoe covers and subsequently transferred to the bedsheet were determined by standard plate culture, colony forming units (CFU), and 16s ribosomal RNA gene sequencing. In vitro laboratory study
* Address correspondence to Honghua Hu, PhD, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109. Australia. E-mail address: [email protected] (H. Hu). Conflicts of Interest: None to report.
Then 107 bacterial cells from each common pathogen S aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecium, and Acinetobacter baumannii were spread
0196-6553/© 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2016.03.020
ARTICLE IN PRESS J. Galvin et al. / American Journal of Infection Control ■■ (2016) ■■-■■
2
over sterile Petri dishes and air dried. Next, each piece of 2 different types of disposal medical shoe covers commonly used in hospitals (polypropylene and polyethylene) was laid on top of the dried bacteria and pressed down 10 times by a sterile spreader. Each contaminated shoe cover piece was subsequently placed on top of a piece of cotton-polyester bedsheet and pressed down across the shoe cover and bedsheet 10 times by a sterile spreader. The number of bacteria attached to shoe covers and rates of bacterial transmission from artificially contaminated shoe covers to bedsheets were determined for each bacterial species in triplicates.
RESULTS Clinical study Bacteria were found contaminating shoe covers, with an average of 226 CFU/cm2 at 5 minutes of walking in patient cubicle and 8,080 CFU/cm2 at 5 minutes of walking in the bathroom (Table 1). Some
Table 1 Number of bacterial colony forming units attached to a shoe cover and subsequently transferred to a hospital bedsheet
Walking location and duration Corridor (5 min) Bathroom (5 min) Patient cubicle (5 min) Patient cubicle (10 min)
Bacteria attached to shoe cover, cm2
Bacteria transferred to bedsheet, cm2
Bacterial transfer rate (shoe cover to bedsheet), %
1,854 ± 1,180 2,598 ± 3,176 226 ± 229
86 ± 170 34 ± 71 4±5
5.70 ± 6.58 0.48 ± 0.86 1.25 ± 2.80
1,074 ± 1,219
32 ± 40
1.12 ± 1.20
NOTE. Values are presented as mean ± SD.
Table 2 Bacterial genus identified on contaminated bedsheet transferred from shoe cover contacted with each floor location Original location Corridor
Bathroom
Patient cubicle
Bacterial genus
No. of samples
Staphylococcus spp Bacillus spp Micrococcus spp Brachybacterium spp Staphylococcus spp Escherichia coli Acinetobacter spp Staphylococcus spp Micrococcus spp
7 2 1 1 5 1 1 8 1
live bacteria from shoe covers were subsequently transferred to bedsheets with a transfer rate ranging from 0.5%-5.7% (Table 1). The day surgery corridor shoe covers yielded the highest transfer rates to the bedsheets. Staphylococcus spp were the principal bacteria transferred from contaminated shoe covers to bedsheets (Table 2).
Laboratory study From 107 bacteria spread and dried, the average live bacteria attached to each shoe cover piece ranged from 219-371 CFU. The transfer rate to the bedsheets for common pathogens ranged from 6.9%-15.1% for polypropylene and 7.5%-17.7% for polyethylene shoe covers. S aureus had the highest transfer rate, whereas P aeruginosa had the lowest transfer rate (Table 3).
DISCUSSION The hospital floors in the day surgery unit were cleaned daily and appeared clean by visual observation. Nevertheless, the shoe covers worn for 5 minutes picked up substantial amounts of live bacteria. This highlights the ability of microorganisms to be present in seemingly clean environments. This study also demonstrated that the live bacteria attached to contaminated disposable medical shoe covers can be subsequently transferred to bedsheets. This has the implication of all patients being equally susceptible to infection regardless of their waiting time prior to surgery, especially if they get into and out of their bed on multiple occasions. The transmission of bacteria from the day surgery floor to the bedsheet opens up the possibility of a patient developing an SSI. In the United States, S aureus accounts for most cases of hospitalacquired infections.9 Many bacteria isolated from contaminated bedsheets in this study were identified as Staphylococci genus (Table 2). The ease at which microorganisms can be transferred to the surgical bedsheets has implications for improved infection control to minimize the burdens of hospital-acquired infections. Mortality associated with SSI has risen dramatically over the last 20 years.6,7 Therefore, small steps toward improved infection control may add to large gains in the quality of patient care. In conclusion, we have demonstrated that disposable medical shoe covers can transmit bacteria, including pathogens, from the hospital floor to the surgical bedsheets, resulting in a potential risk for hospital-acquired infections. Infection control requires the minimization of risks to prevent patients developing hospital-acquired infections. Unfortunately, the use and removal of patient shoe covers are not dictated in infection control guidelines. 10 This study
Table 3 Number of bacterial colony forming units from 107 dried bacterial cells attached to one piece of shoe cover and subsequently transferred to hospital bedsheet
Bacterial species Staphylococcus aureus, ATCC 25923 Staphylococcus epidermidis, ATCC 35984 Enterococcus faecium, ATCC 35667 Acinetobacter baumannii, ATCC 19606 Pseudomonas aeruginosa, ATCC 25619 Escherichia coli, K12 C600 NOTE. Values are presented as mean ± SD. PE, Polyethylene; PP, Polypropylene.
Shoe cover material
No. of bacteria attached to shoe cover
No. of bacteria transferred to bedsheet
Bacterial transfer rate (shoe cover to bedsheet), %
PP PE PP PE PP PE PP PE PP PE PP PE
306 ± 22 371 ± 23 279 ± 39 296 ± 21 293 ± 25 346 ± 29 219 ± 33 259 ± 26 297 ± 28 319 ± 41 280 ± 47 312 ± 56
54 ± 4 81 ± 6 39 ± 5 50 ± 3 40 ± 5 54 ± 7 25 ± 4 33 ± 6 22 ± 4 26 ± 4 38 ± 11 45 ± 12
15.08 ± 0.66 17.74 ± 0.53 12.36 ± 0.39 14.53 ± 0.71 11.87 ± 0.92 13.47 ± 1.10 10.16 ± 0.35 11.15 ± 0.86 6.92 ± 0.50 7.51 ± 0.68 8.92 ± 1.23 11.07 ± 0.83
ARTICLE IN PRESS J. Galvin et al. / American Journal of Infection Control ■■ (2016) ■■-■■
demonstrates a potentially overlooked source of contamination and possible infection. We suggest an infection control policy should be considered to prevent patients returning to their bed with contaminated disposable shoe covers because this simple measure may reduce surgical bed contamination and the number of SSIs and their associated detrimental impact. Acknowledgments We would like to acknowledge the friendly Macquarie University Hospital staff for their support of this study. Lillian Kelly Oliveira Lopes was in receipt of CAPES Scholarship (process no. 99999.006360/2014-09). Dayane de Melo Costa was in receipt of Cotutelle iMQRES scholarship (allocation no. 2015142) and CAPES Scholarship (process no.99999.006361/2014-05). References 1. Eisen DB. Surgeon’s garb and infection control: what’s the evidence? J Am Acad Dermatol 2011;64:960, e1-20.
3
2. Cho OH, Baek EH, Bak MH, Suh YS, Park KH, Kim S, et al. The effect of targeted decolonization on methicillin-resistant Staphylococcus aureus colonization or infection in a surgical intensive care unit. Am J Infect Control 2016;44:533-8. 3. Wagenvoort JH, De Brauwer EI, Penders RJ, Willems RJ, Top J, Bonten MJ. Environmental survival of vancomycin-resistant Enterococcus faecium. J Hosp Infect 2011;77:282-3. 4. Magill SS, Hellinger W, Cohen J, Kay R, Bailey C, Boland B, et al. Prevalence of healthcare-associated infections in acute care hospitals in Jacksonville, Florida. Infect Control Hosp Epidemiol 2012;33:283-91. 5. Ott E, Saathoff S, Graf K, Schwab F, Chaberny IF. The prevalence of nosocomial and community acquired infections in a university hospital: an observational study. Dtsch Arztebl Int 2013;110:533-40. 6. Merkow RP, Ju MH, Chung JW, Hall BL, Cohen ME, Williams MV, et al. Underlying reasons associated with hospital readmission following surgery in the United States. JAMA 2015;313:483-95. 7. Urquhart DM, Hanna FS, Brennan SL, Wluka AE, Leder K, Cameron PA, et al. Incidence and risk factors for deep surgical site infection after primary total hip arthroplasty: a systematic review. J Arthroplasty 2010;25:1216-22, e1-3. 8. Ercole FF, Franco LM, Macieira TG, Wenceslau LC, de Resende HI, Chianca TC. Risk of surgical site infection in patients undergoing orthopedic surgery. Rev Lat Am Enfermagem 2011;19:1362-8. 9. Weigelt JA, Lipsky BA, Tabak YP, Derby KG, Kim M, Gupta V. Surgical site infections: causative pathogens and associated outcomes. Am J Infect Control 2010;38:112-20. 10. Centers for Disease Control and Prevention. Surgical site infection (SSI) event. 2016. Available from: http://www.cdc.gov/nhsn/PDFs/pscManual/9pscSSIcurrent .pdf. Accessed January 25, 2016.