Journal
of Hospital
Theatre
Infection
over-shoes do not reduce operating floor bacterial counts
H. Humphreys, Department
17, 117-l 23
(1991)
R. J. Marshall, V. E. Ricketts, D. S. Reeves
of Medical
Microbiology, Trym, Bristol
Southmead BSlO SNB
Accepted for publication
theatre
A. J. Russell Hospital,
20 November
and
Westbury-on-
1990
Summary:
Occasional staff or visitors to operating theatres are usually requested to don over-shoes as this is perceived to reduce bacterial floor colony counts. However, this entails some expense and considerable inconvenience. Using disposable surface contact plates floor bacterial counts were measured four times a day at five different sites during the 5 normal working days of one 2-week period in a general operating theatre when over-shoes were worn and one 2-week period when over-shoes were not worn. There was no significant difference in the mean bacterial floor colony counts between the two periods according to sampling times or sites. As in Intensive Therapy units, over-shoes should no longer be used in general operating theatres. Keywords: measures.
Operating
theatre;
over-shoes;
floor
counts;
infection
control
Introduction
Many postoperative wound infections are acquired during surgery when the patient is in the operating theatre. Consequently, a series of measures has evolved over the years in an attempt to reduce sepsis by lowering the colony counts of potential pathogens in the theatre environment. Scrubbing-up and the use of gowns and masks are designed to lessen the risk of acquisition from the operating team. Air conditioning, the use of theatre-designated footwear or over-shoes and regular cleaning all minimize the number of bacteria in the environment that may contaminate and subsequently infect a wound. It has been the practice in most UK hospitals for theatre staff to wear theatre shoes or over-shoes. Full-time staff or those in theatre regularly, for example surgeons, theatre nurses and portering staff usually have personal theatre footwear. Occasional staff or visitors in contrast don over-shoes at a fixed point before proceeding into the theatre area proper. In a survey Correspondence BS2 SHW. 0195-6701/91/020117+07
to: Dr H. Humphreys,
Department
SO3.00/0
of Microbiology,
Bristol Royal Infirmary, 0 1991 The Hospital
117
Infection
Bristol Society
118
H. Humphreys
et al.
carried out by the Centers for Disease Control in the United States of America, between October 1976 and July 1977, 53% of institutions requested staff to wear shoe coverings but in those hospitals not advocating such a measure, 83% insisted that shoes be cleaned on a routine basis.’ In operating theatres in this country, however, there is a strongly held view that wounds are at risk of infection from bacteria carried into theatre and consequently theatre shoes and over-shoes are perceived as a measure designed to minimize this. The use of such over-shoes in our hospital has a direct cost of approximately ES00 per year and is largely confined to escort nurses bringing and collecting patients for operation. This expense together with the loss of time, possible contamination of the hands and the dubious effectiveness of such a measure, prompted us to carry out a trial in one of our theatres comparing bacterial floor counts during periods w”hen over-shoes were and were not being used. Materials
and methods
Study outline This study was undertaken in a general operating theatre at our hospital which is used for a variety of major and minor surgical procedures. A plan of the theatre is outlined in Figure 1. Entrance is via a notional barrier which separates the operating theatre from the outside. This is the location at which over-shoes are donned by people who are temporary visitors to the theatre and therefore do not have their own theatre shoes. Theatre floors are cleaned daily at midnight with liquid detergent, (‘Hospec’ BP) 5 ml in 5 1 of water, while furniture and ledges are cleaned with similar detergent before 7.00 a.m. each morning. Spillages arising during the course of surgery onto the floor or other surfaces are cleaned in the same manner between cases. One per cent hypochlorite is used if this involves inoculation-risk patients. Floor bacterial counts were measured four times a day during each of the 5 normal working days of two periods of two weeks during the months of February/March. The sampling sites are indicated in Figure 1 and each of these was sampled during four periods of the day: between 7.00 and 8.00a.m.; 11.00 and 12.00a.m.; 2.00 and 3.00p.m.; and 4.00 and 5.00p.m. These times were chosen to reflect the variation in bacterial counts occurring throughout the day. During the first 2-week period, over-shoes were worn by visitors and escort nurses. The over-shoes were 0.007 inch thick transparent blue PVC (Surgicon Ltd). Following a 2-week interval sampling recommenced for 2 weeks when no theatre over-shoes were available at the barrier with notices placed at the entry to the operating theatre informing people of the change in practice. During the periods of the study records of surgical procedures carried out were kept and these to monitor whether were then classified into ‘dirty ’ , ‘clean’ or ‘intermediate’ the type of procedure varied significantly between the two trial periods.
Over-shoes
and theatre
floor counts
TABLE
Anaesthehc Roam
Scrub up area
- $
Earner
*I*
Figure 1. Plan of theatre and sampling sites. *N* Site of sampling: 1, outside the theatre area; 2, inside theatre by anaesthetic room door; 3, inside theatre by main door; 4, under operating table; 5, under theatre clock.---Flow of patients;\ / swing doors except where indicated.
Microbiology Disposable surface contact plates (‘Count-Tact’, Bio Merieux) approximately 55 mm in diameter containing trypticase agar were used. These plates have a convex surface and the site was sampled by pressing the surface firmly
120
H. Humphreys
et al.
onto the floor. Each site was sampled with two plates, both incubated at 37°C for 40 h, one in 5% CO, and the other anaerobically. Each plate has a grid on to which the agar has been poured and this enables total colony counts to be calculated for both plates. In addition specific counts of Staphylococcus aweus and Clostridium perfringens were carried out. Presumptive colonies of S. aUYeUs were identified by specific latex agglutination (‘Staphaurex’, Wellcome Diagnostics, Dartford) and C. perfringens by inhibition of lecithinase by specific antiserum. The results from the floor bacterial counts were entered into the Oxstat 1.11 and mean values, standard computer statistics package, version deviation, co-efficient of variance and paired ‘t’-tests of significance calculated. Prior to the start of the study ethical approval was obtained from the Southmead District Medical Research and Ethical Committee and the Division of Surgery. Results
The results of total floor bacterial counts during the 2-week periods with and without over-shoes are outlined in Table I. As Site 1 (beyond the barrier) is considered to be in the theatre area but outside the theatre itself figures are given including and excluding the results from this site. There was no statistically significant difference in the mean bacterial floor colony counts between the two periods studied. Table II outlines the results according to site and sampling time. There was no significant difference in the mean counts for three of the sites, one was borderline and one (site 5) was significantly different, but here higher bacterial counts occurred when over-shoes were worn. For sampling times there were no differences between periods when over-shoes were or were not worn even at the 10% level of significance. Clostridium perfringens was not isolated from the theatre floor during either period of the study. One to two colonies of S. aUYeUs were recovered Table
I. Total
theatre floor Mean
bacterial
colony counts Standard deviation
*P value
All sites With over-shoes Without over-shoes All sites except
test.
22.27 22.35
o-5
65.38 70.60
22.38 20.89
0.4
site 1
With over-shoes Without over-shoes * Paired-t
64.37 67.51
Over-shoes Table
2. Variation
of poor bacterial
and theatre
floor counts
colony counts according
Over-shoes worn
Mean bacterial count
yes
to site and sampling Standard deviation
121 time *P value
no
60.33 53.65
24.70 24.54
0.59
2
yes no
51.50 64.86
21.24 11.06
0.34
3
yes no
52.53 76.20
20.62 29.35
0.05
4
yes no
66.86 62.49
15.19 27.23
0.83
5
yes no
90.63 78.85
8.27 13.85
0.03
yes no
77.23 81.92
22-13 11.42
0.69
B
yes no
67.24 49.43
21.77 17.54
0.23
C
yes no
63.81 76.99
19.94 27.26
0.34
D
yes no
50.93 60.50
25.28 17.17
0.20
Sampling A
time$
* Paired t-test. t See Fig. 1 for site locations. $A, 7-8 a.m.; B, 11-12 a.m.; C, 2-3 p.m.;
D, 4-5 p.m.
at least once each day during the initial period when over-shoes were being worn. Eleven samples were positive on day 6, explained perhaps by the fact that half of the six operations carried out were classified as ‘dirty’. Twelve of the specimens from the period when over-shoes were not worn were positive for S. QUY~USbut there were 5 days during this period when S. aureus was not recovered. On one day, however, day 6, three of the four positive samples had colony counts of 200. There is no obvious explanation for this. Activity in the theatre during this day was minimal as only one operation was carried out. Discussion
This study has demonstrated that the use of theatre over-shoes does not lead to a significant reduction in bacterial floor counts in a general operating
122
H. Humphreys
et al.
theatre as there was no significant difference in the mean colony counts between the two study periods. When the results are analysed according to sampling times, there was no significant difference whether over-shoes were or were not worn. There was a significant difference in colony counts between the two study periods for one sampling site but here the use of over-shoes was associated with higher not lower counts. Indeed for three of the sites and one of the sampling times the use of over-shoes was associated with higher bacterial colony counts. Clostridium perfringens was not recovered from any of the samples but S. aUreaS was isolated on a number of occasions during both phases of the study, Except for three samples, colony counts were low and would be unlikely to contribute to theatre-acquired infection. The isolation of a significant amount of S. aUreUS during one day when theatre over-shoes were not worn is not easily explained. This occurred during a relatively quiet day in theatre when no ‘dirty’ operations were carried out. Staphylococcus aweus was recovered on fewer days during this period and this suggests that the failure to wear over-shoes by temporary staff did not contribute significantly to an increase in floor counts. Minor changes in any event are unlikely to play a significant part in the aetiology of wound infection during the postoperative period. Since Charnley and Eftekhar’s work in the late 1960s describing the importance of clean air and aseptic techniques in reducing the incidence of great emphasis has been placed on the infected prosthetic hip-joints,2 importance of reducing the numbers of bacteria in the environment in an effort to reduce postoperative infection. It is debatable whether floor bacterial counts, except when indicating gross contamination, play a major part in infections where prosthetic material is not involved and this applies to the majority of surgical operations carried out. Theatre shoes and over-shoes significantly reduced transfer of bacteria to a disinfected study area and only over-shoes led to a fall in bacterial counts in a non-disinfected area in one study.3 This study was carried out looking at one particular area of theatre only using volunteers and may not have reflected changes in other parts of the theatre area. Bacteria, especially staphylococci, can be transferred from contaminated to clean areas on the soles of shoes but measures such as the use of tacky or disinfectant mats do not appreciably reduce such transfer.’ A study by Nagai and colleagues has shown that as the point where footwear is changed is moved further away from the theatre area itself, so the area of maximum contamination moves, indicating that exchange or change of footwear should take place as far away from the operating theatre itself as possible.5 Bacterial floor counts generally increase during the middle of the day but different footwear (ordinary shoes, clean shoes or shoe covers) may not affect floor contamination.6 There is some scepticism about the effectiveness of over-shoes as a measure to reduce theatre floor contamination. Approximately 10% of plastic over-shoes split during wearing and their
Over-shoes
and theatre
floor counts
123
application and removal may lead to significant hand contamination which is of potentially greater significance.7 In intensive therapy units, over-shoes are no longer considered a useful infection control measure in reducing sepsis.8,9 It seems likely that a similar recommendation can now be made for general operating theatres except where prosthetic joint replacement is done. Indeed the banning of over-shoes may result in decreased contamination of hands by potential pathogens,7 the occurrence of which may explain the isolation of S. aweus everyday when over-shoes were worn compared with only half of the ten days when they were not worn. As no conclusive evidence has ever been produced to suggest that theatre over-shoes reduce postoperative sepsis by reducing floor bacterial counts and as this practice is not without its cost, we conclude that theatre over-shoes should no longer be worn by temporary or visiting theatre staff.
We wish to thank Dr Mulvein for his help in organizing this study, Dr Alan Hedges advice on the statistical analysis of our results and Mrs Dorrie Morris for typing manuscript.
for the
Refesences 1. Garner JS, Emori TG, Haley RW. Operating room practices for the control of infection in US hospitals, October 1976 to July 1977. Surg Gynaecol Obstet 1982; 155: 873-880. J, Eftekhar N. Postoperative infection in total prosthetic replacement 2. Charnley arthroplasty of the hip-joint. Br J Surg 1969; 56: 641-694. 3. Copp G, Slelak L, Dudley N, Mailhot CB. Footwear practices and operating room contamination. Nurs Res 1990; 36: 366-369. EJL, Babb JR, Lilly HA. Ward floors and other 4. Ayliffe GAJ, Collins BJ, Lowbury surfaces as reservoirs of hospital infection. r Hyg 1967; 6.5: 515-536. of an 5. Nagai I, Kadota M, Takechi M et al. Studies on the mode of bacterial contamination operating theatre corridor floor. J Hosp Infect 1984; 5: 50-S. A, Malmborg AS. The influence of different footwear on floor bacterial 6. Hambraeus counts. Stand J Infect Dis 1979; 11: 243-246. 7. Carter R. Ritual and risk. Nursing Times 1990; 86: 63-64. 8. Daschner FD. Useful and useless hygienic techniques in intensive care units. Intensive
Care Med 1985; 11: 280-283. 9. Gaya H. Is it necessary for staff and visitors in an intensive gowns and overshoes? J Hosp Infect 1980; 1: 369-371.
care unit to wear masks, hats,
of Hospital
Theatre
Infection
over-shoes do not reduce operating floor bacterial counts
H. Humphreys, Department
17, 117-l 23
(1991)
R. J. Marshall, V. E. Ricketts, D. S. Reeves
of Medical
Microbiology, Trym, Bristol
Southmead BSlO SNB
Accepted for publication
theatre
A. J. Russell Hospital,
20 November
and
Westbury-on-
1990
Summary:
Occasional staff or visitors to operating theatres are usually requested to don over-shoes as this is perceived to reduce bacterial floor colony counts. However, this entails some expense and considerable inconvenience. Using disposable surface contact plates floor bacterial counts were measured four times a day at five different sites during the 5 normal working days of one 2-week period in a general operating theatre when over-shoes were worn and one 2-week period when over-shoes were not worn. There was no significant difference in the mean bacterial floor colony counts between the two periods according to sampling times or sites. As in Intensive Therapy units, over-shoes should no longer be used in general operating theatres. Keywords: measures.
Operating
theatre;
over-shoes;
floor
counts;
infection
control
Introduction
Many postoperative wound infections are acquired during surgery when the patient is in the operating theatre. Consequently, a series of measures has evolved over the years in an attempt to reduce sepsis by lowering the colony counts of potential pathogens in the theatre environment. Scrubbing-up and the use of gowns and masks are designed to lessen the risk of acquisition from the operating team. Air conditioning, the use of theatre-designated footwear or over-shoes and regular cleaning all minimize the number of bacteria in the environment that may contaminate and subsequently infect a wound. It has been the practice in most UK hospitals for theatre staff to wear theatre shoes or over-shoes. Full-time staff or those in theatre regularly, for example surgeons, theatre nurses and portering staff usually have personal theatre footwear. Occasional staff or visitors in contrast don over-shoes at a fixed point before proceeding into the theatre area proper. In a survey Correspondence BS2 SHW. 0195-6701/91/020117+07
to: Dr H. Humphreys,
Department
SO3.00/0
of Microbiology,
Bristol Royal Infirmary, 0 1991 The Hospital
117
Infection
Bristol Society
118
H. Humphreys
et al.
carried out by the Centers for Disease Control in the United States of America, between October 1976 and July 1977, 53% of institutions requested staff to wear shoe coverings but in those hospitals not advocating such a measure, 83% insisted that shoes be cleaned on a routine basis.’ In operating theatres in this country, however, there is a strongly held view that wounds are at risk of infection from bacteria carried into theatre and consequently theatre shoes and over-shoes are perceived as a measure designed to minimize this. The use of such over-shoes in our hospital has a direct cost of approximately ES00 per year and is largely confined to escort nurses bringing and collecting patients for operation. This expense together with the loss of time, possible contamination of the hands and the dubious effectiveness of such a measure, prompted us to carry out a trial in one of our theatres comparing bacterial floor counts during periods w”hen over-shoes were and were not being used. Materials
and methods
Study outline This study was undertaken in a general operating theatre at our hospital which is used for a variety of major and minor surgical procedures. A plan of the theatre is outlined in Figure 1. Entrance is via a notional barrier which separates the operating theatre from the outside. This is the location at which over-shoes are donned by people who are temporary visitors to the theatre and therefore do not have their own theatre shoes. Theatre floors are cleaned daily at midnight with liquid detergent, (‘Hospec’ BP) 5 ml in 5 1 of water, while furniture and ledges are cleaned with similar detergent before 7.00 a.m. each morning. Spillages arising during the course of surgery onto the floor or other surfaces are cleaned in the same manner between cases. One per cent hypochlorite is used if this involves inoculation-risk patients. Floor bacterial counts were measured four times a day during each of the 5 normal working days of two periods of two weeks during the months of February/March. The sampling sites are indicated in Figure 1 and each of these was sampled during four periods of the day: between 7.00 and 8.00a.m.; 11.00 and 12.00a.m.; 2.00 and 3.00p.m.; and 4.00 and 5.00p.m. These times were chosen to reflect the variation in bacterial counts occurring throughout the day. During the first 2-week period, over-shoes were worn by visitors and escort nurses. The over-shoes were 0.007 inch thick transparent blue PVC (Surgicon Ltd). Following a 2-week interval sampling recommenced for 2 weeks when no theatre over-shoes were available at the barrier with notices placed at the entry to the operating theatre informing people of the change in practice. During the periods of the study records of surgical procedures carried out were kept and these to monitor whether were then classified into ‘dirty ’ , ‘clean’ or ‘intermediate’ the type of procedure varied significantly between the two trial periods.
Over-shoes
and theatre
floor counts
TABLE
Anaesthehc Roam
Scrub up area
- $
Earner
*I*
Figure 1. Plan of theatre and sampling sites. *N* Site of sampling: 1, outside the theatre area; 2, inside theatre by anaesthetic room door; 3, inside theatre by main door; 4, under operating table; 5, under theatre clock.---Flow of patients;\ / swing doors except where indicated.
Microbiology Disposable surface contact plates (‘Count-Tact’, Bio Merieux) approximately 55 mm in diameter containing trypticase agar were used. These plates have a convex surface and the site was sampled by pressing the surface firmly
120
H. Humphreys
et al.
onto the floor. Each site was sampled with two plates, both incubated at 37°C for 40 h, one in 5% CO, and the other anaerobically. Each plate has a grid on to which the agar has been poured and this enables total colony counts to be calculated for both plates. In addition specific counts of Staphylococcus aweus and Clostridium perfringens were carried out. Presumptive colonies of S. aUYeUs were identified by specific latex agglutination (‘Staphaurex’, Wellcome Diagnostics, Dartford) and C. perfringens by inhibition of lecithinase by specific antiserum. The results from the floor bacterial counts were entered into the Oxstat 1.11 and mean values, standard computer statistics package, version deviation, co-efficient of variance and paired ‘t’-tests of significance calculated. Prior to the start of the study ethical approval was obtained from the Southmead District Medical Research and Ethical Committee and the Division of Surgery. Results
The results of total floor bacterial counts during the 2-week periods with and without over-shoes are outlined in Table I. As Site 1 (beyond the barrier) is considered to be in the theatre area but outside the theatre itself figures are given including and excluding the results from this site. There was no statistically significant difference in the mean bacterial floor colony counts between the two periods studied. Table II outlines the results according to site and sampling time. There was no significant difference in the mean counts for three of the sites, one was borderline and one (site 5) was significantly different, but here higher bacterial counts occurred when over-shoes were worn. For sampling times there were no differences between periods when over-shoes were or were not worn even at the 10% level of significance. Clostridium perfringens was not isolated from the theatre floor during either period of the study. One to two colonies of S. aUYeUs were recovered Table
I. Total
theatre floor Mean
bacterial
colony counts Standard deviation
*P value
All sites With over-shoes Without over-shoes All sites except
test.
22.27 22.35
o-5
65.38 70.60
22.38 20.89
0.4
site 1
With over-shoes Without over-shoes * Paired-t
64.37 67.51
Over-shoes Table
2. Variation
of poor bacterial
and theatre
floor counts
colony counts according
Over-shoes worn
Mean bacterial count
yes
to site and sampling Standard deviation
121 time *P value
no
60.33 53.65
24.70 24.54
0.59
2
yes no
51.50 64.86
21.24 11.06
0.34
3
yes no
52.53 76.20
20.62 29.35
0.05
4
yes no
66.86 62.49
15.19 27.23
0.83
5
yes no
90.63 78.85
8.27 13.85
0.03
yes no
77.23 81.92
22-13 11.42
0.69
B
yes no
67.24 49.43
21.77 17.54
0.23
C
yes no
63.81 76.99
19.94 27.26
0.34
D
yes no
50.93 60.50
25.28 17.17
0.20
Sampling A
time$
* Paired t-test. t See Fig. 1 for site locations. $A, 7-8 a.m.; B, 11-12 a.m.; C, 2-3 p.m.;
D, 4-5 p.m.
at least once each day during the initial period when over-shoes were being worn. Eleven samples were positive on day 6, explained perhaps by the fact that half of the six operations carried out were classified as ‘dirty’. Twelve of the specimens from the period when over-shoes were not worn were positive for S. QUY~USbut there were 5 days during this period when S. aureus was not recovered. On one day, however, day 6, three of the four positive samples had colony counts of 200. There is no obvious explanation for this. Activity in the theatre during this day was minimal as only one operation was carried out. Discussion
This study has demonstrated that the use of theatre over-shoes does not lead to a significant reduction in bacterial floor counts in a general operating
122
H. Humphreys
et al.
theatre as there was no significant difference in the mean colony counts between the two study periods. When the results are analysed according to sampling times, there was no significant difference whether over-shoes were or were not worn. There was a significant difference in colony counts between the two study periods for one sampling site but here the use of over-shoes was associated with higher not lower counts. Indeed for three of the sites and one of the sampling times the use of over-shoes was associated with higher bacterial colony counts. Clostridium perfringens was not recovered from any of the samples but S. aUreaS was isolated on a number of occasions during both phases of the study, Except for three samples, colony counts were low and would be unlikely to contribute to theatre-acquired infection. The isolation of a significant amount of S. aUreUS during one day when theatre over-shoes were not worn is not easily explained. This occurred during a relatively quiet day in theatre when no ‘dirty’ operations were carried out. Staphylococcus aweus was recovered on fewer days during this period and this suggests that the failure to wear over-shoes by temporary staff did not contribute significantly to an increase in floor counts. Minor changes in any event are unlikely to play a significant part in the aetiology of wound infection during the postoperative period. Since Charnley and Eftekhar’s work in the late 1960s describing the importance of clean air and aseptic techniques in reducing the incidence of great emphasis has been placed on the infected prosthetic hip-joints,2 importance of reducing the numbers of bacteria in the environment in an effort to reduce postoperative infection. It is debatable whether floor bacterial counts, except when indicating gross contamination, play a major part in infections where prosthetic material is not involved and this applies to the majority of surgical operations carried out. Theatre shoes and over-shoes significantly reduced transfer of bacteria to a disinfected study area and only over-shoes led to a fall in bacterial counts in a non-disinfected area in one study.3 This study was carried out looking at one particular area of theatre only using volunteers and may not have reflected changes in other parts of the theatre area. Bacteria, especially staphylococci, can be transferred from contaminated to clean areas on the soles of shoes but measures such as the use of tacky or disinfectant mats do not appreciably reduce such transfer.’ A study by Nagai and colleagues has shown that as the point where footwear is changed is moved further away from the theatre area itself, so the area of maximum contamination moves, indicating that exchange or change of footwear should take place as far away from the operating theatre itself as possible.5 Bacterial floor counts generally increase during the middle of the day but different footwear (ordinary shoes, clean shoes or shoe covers) may not affect floor contamination.6 There is some scepticism about the effectiveness of over-shoes as a measure to reduce theatre floor contamination. Approximately 10% of plastic over-shoes split during wearing and their
Over-shoes
and theatre
floor counts
123
application and removal may lead to significant hand contamination which is of potentially greater significance.7 In intensive therapy units, over-shoes are no longer considered a useful infection control measure in reducing sepsis.8,9 It seems likely that a similar recommendation can now be made for general operating theatres except where prosthetic joint replacement is done. Indeed the banning of over-shoes may result in decreased contamination of hands by potential pathogens,7 the occurrence of which may explain the isolation of S. aweus everyday when over-shoes were worn compared with only half of the ten days when they were not worn. As no conclusive evidence has ever been produced to suggest that theatre over-shoes reduce postoperative sepsis by reducing floor bacterial counts and as this practice is not without its cost, we conclude that theatre over-shoes should no longer be worn by temporary or visiting theatre staff.
We wish to thank Dr Mulvein for his help in organizing this study, Dr Alan Hedges advice on the statistical analysis of our results and Mrs Dorrie Morris for typing manuscript.
for the
Refesences 1. Garner JS, Emori TG, Haley RW. Operating room practices for the control of infection in US hospitals, October 1976 to July 1977. Surg Gynaecol Obstet 1982; 155: 873-880. J, Eftekhar N. Postoperative infection in total prosthetic replacement 2. Charnley arthroplasty of the hip-joint. Br J Surg 1969; 56: 641-694. 3. Copp G, Slelak L, Dudley N, Mailhot CB. Footwear practices and operating room contamination. Nurs Res 1990; 36: 366-369. EJL, Babb JR, Lilly HA. Ward floors and other 4. Ayliffe GAJ, Collins BJ, Lowbury surfaces as reservoirs of hospital infection. r Hyg 1967; 6.5: 515-536. of an 5. Nagai I, Kadota M, Takechi M et al. Studies on the mode of bacterial contamination operating theatre corridor floor. J Hosp Infect 1984; 5: 50-S. A, Malmborg AS. The influence of different footwear on floor bacterial 6. Hambraeus counts. Stand J Infect Dis 1979; 11: 243-246. 7. Carter R. Ritual and risk. Nursing Times 1990; 86: 63-64. 8. Daschner FD. Useful and useless hygienic techniques in intensive care units. Intensive
Care Med 1985; 11: 280-283. 9. Gaya H. Is it necessary for staff and visitors in an intensive gowns and overshoes? J Hosp Infect 1980; 1: 369-371.
care unit to wear masks, hats,
