Abstract
INTRODUCTION
Infection after joint arthroplasty is a disastrous complication. Implants used in hip arthroplasty increase the risk of infection from organisms of low pathogenicity. Potential reservoirs, that have not been assessed as yet, are the supports used for patient positioning in hip arthroplasty. The purpose of this study was to assess these supports for presence of bacterial pathogens.
SUBJECTS AND METHODS
We studied 40 supports used in 20 hip arthroplasty procedures. Tryptone soya agar plates were used to sample these supports. All agar plates were incubated at 37°C for 48 h.
RESULTS
Of the 20 anterior supports, 17 (85%) showed bacterial colonisation; of the 20 posterior supports, 10 (50%) had bacterial colonisation. Fourteen (52%) supports were contaminated with one organism, 9 (33%) with two organisms, three (11%) with three organisms and one (4%) with four organisms. Coagulase-negative staphylococci were the most common isolated organisms (61%) followed by coryneforms (10%) and bacilli (10%). Anterior supports had two times more colony forming units compared to the posterior supports.
CONCLUSIONS
This study showed contamination of supports used for positioning patients during hip arthroplasty. It reflects poor cleaning practice and certainly raises the possibility that a high bacterial load on these supports may contribute to higher infection rates in hip arthroplasties. The study raises concerns related to contamination of supports, as there is a potential for cross-infection, wound problems, and deep sepsis around implants which could be disastrous. While colonisation does not equate with infection, we suggest thorough cleaning of the supports before and after every surgical procedure.
Keywords: Arthroplasty, Organisms, Contamination, Deep sepsis
The number of total hip arthroplasties being performed is increasing year on year. As per the statistics on National Joint Registry, in year 2008, 52,104 hip arthroplasties were performed in England and Wales within NHS hospitals. Infection after total joint arthroplasty is a serious complication and the result of infection can be disastrous. Implants used in hip arthroplasty increase the risk of infection from organisms of low pathogenicity.1
Recently, tourniquets used in total knee arthroplasty were assessed by Ahmed et al.,2 who found colonisation of all tourniquets with one or more bacteria including methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas spp., etc. A potential reservoir, that has not been assessed as yet, are the supports used in positioning of patients in hip arthroplasty. The purpose of this study was to assess these supports for presence of bacterial pathogens.
Subjects and Methods
Lateral decubitus position is the commonest patient position employed during hip arthroplasty. Supports are placed on the front and back to maintain this position and provide support for bony pelvis during the surgery (Figs 1 and 2). Most commercially available systems consist of an anterior support for anterior superior iliac spine or the symphysis pubis and posterior support for the sacrum. The supports in our institution are padded and stored in a basket in the anaesthetic room.
Figure 1.
Anterior support.
Figure 2.
Posterior support.
A total of 40 supports (20 anterior and 20 posterior) were used in 20 hip arthroplasty procedures. Six supports available in our theatre were sampled multiple times during the study. There were no cleaning methods in place to clean the posts between cases. We used tryptone soya agar plates for culture. Samples were taken from the padded surface of the supports; these surfaces are in contact with the patient during the surgical procedure. Microbiological sampling of the supports was done by pressing the agar plates once on the contact surface of the supports. All agar plates were incubated at 37°C for 48 h. Results were documented by bacterial type and the number of colony forming units (CFUs). Mean number of CFUs were compared between the anterior and the posterior supports.
Results
Of the 20 anterior supports, 17 (85%) showed bacterial colonisation; of the 20 posterior supports, 10 (50%) had bacterial colonisation. Of these contaminated supports, 14 (52%) were contaminated with one organism, 9 (33%) were contaminated with two organisms, three (11%) with three organisms and one (4%) with four organisms (Table 1).
Table 1.
Colony counts and growths
| No. | Anterior support | Posterior support | Total |
|---|---|---|---|
| 1 | 0 | 21 CNS | 21 |
| 2 | 87 CNS | > 100 (> 100 CNS, 10 ASB) | >187 |
| 3 | 33 CNS | 21 CNS | 54 |
| 4 | 11 CNS | 0 | 11 |
| 5 | 25 CNS | 0 | 25 |
| 6 | 30 CNS | 0 | 30 |
| 7 | 5 CNS | 0 | 5 |
| 8 | 0 | 0 | 0 |
| 9 | > 100 (CNS, coryneforms, 1 pseudomonas) | 3 coryneforms | >103 |
| 10 | 0 | 1 Gram +ve spore-bearing bacillus | 1 |
| 11 | 12 CNS | 5 (2 coryneforms, 1 CNS, 2 micrococci) | 17 |
| 12 | 2 (1 micrococcus, 1 CNS) | 1 CNS | 3 |
| 13 | 74 (54 CNS, 16 coryneforms, 3 micrococci, 1 bacillus) | 0 | 74 |
| 14 | 6 (5 CNS, 1 Gram -ve coliform) | 0 | 6 |
| 15 | 74(9CNS, 65 Coryneforms) | 0 | 74 |
| 16 | > 100(20 bacilli, 200 CNS) | 38 (12 bacilli, 26 CNS) | >138 |
| 17 | 200 CNS | 0 | 200 |
| 18 | 23 (21 CNS, 1 bacillus, 1 micrococcus) | 2 (1 coryneform, 1 Streptococcus viridans) | 25 |
| 19 | 10 (9 CNS, 1 enterococcus) | 0 | 10 |
| 20 | > 200 CNS | 60 (3 bacilli, 57 CNS) | >260 |
| Total | >992 | >252 | > 1244 |
CNS, coagulase-negative staphylococci; ASB, aerobic spore bearers.
Coagulase-negative staphylococci were the most common isolated organisms (61%) followed by coryneforms (10%) and bacilli (10%). Four supports were extensively contaminated to an extent that an exact number of CFUs was impossible. These counts were labelled as > 100 or > 200. The mean number of CFUs on the anterior supports was 58 compared to 25 on the posterior supports. Anterior supports thus had more than twice more CFUs compared to the posterior supports (Table 1).
There were no infections during the trial period; thus, correlation of infection with the organisms found on the supports was not possible.
Discussion
There have been studies to show that orthopaedic surgical site infection is responsible for increase in hospital stay, increase in re-hospitalisation rates, and increase in healthcare costs.3
This study showed contamination of supports used in positioning of patients during hip arthroplasty. It reflects poor cleaning practice and certainly raises the possibility that a high bacterial load on these supports may contribute to higher infection rate in hip arthroplasties. Both anterior and the posterior supports routinely lie very close to the proximal extent of incision made in different surgical approaches for hip arthroplasty surgery. Using colonised supports raises the possibility of transmission of pathogenic organisms to the patients immediately before surgery, thus increasing the risk of surgical site infection. Direct inoculation from the skin adjacent to the incision is one of the major causes of deep-seated postoperative sepsis.4
Coagulase-negative Staphylococcus was the commonest organism isolated in our study. It is the commonest cause of joint infection in knee replacement surgery.5,6 This organism has also been found to be the predominant organism in infection following total hip arthroplasty.7 It has also been found to be the commonest source of intra-operative bacterial contamination in operations for primary hip and knee replacements.8 Pseudomonas spp. have been isolated from superficial wound infection following total hip replacement.9 Enterococcus spp. have more frequently been recognised as a cause of super infection in the surgical patient.10
We also found that anterior supports were more contaminated than the posterior supports. This is most probably due to closer proximity of the anterior supports to the perineum, which is a ‘hot-bed’ of bacteria.
Our study raises concerns related to contamination of supports as there is a potential for cross-infection, wound problems, and deep sepsis around implants which could be disastrous. Presence of foreign material, such as the femoral and acetabular implants results in a 6-fold reduction in the number of inoculates needed to cause infection.11
Exclusion of supports from the operative field by surgical draping does not preclude them from being implicated in surgical site infection. The commonly used disposable non-woven drapes, although resistant to bacterial penetration, have been found to be penetrable to bacteria after 90 min.12
Conclusions
We have shown contamination of supports used in hip arthroplasty. While colonisation does not equate with infection, we suggest thorough cleaning of these supports before and after every surgical procedure using disinfectant wipes that are widely available in theatres.
Acknowledgments
The authors thank Drs Ibrahim (Consultant Microbiologist) and David Lewis (Senior Microbiology Technician) at the Weston General Hospital Microbiology Department for their assistance in this study.
References
- 1.Nelson JP, Glassburn AR, Jr, Talbott RD, McElhinney JP. Clean room operating rooms. Clin Orthop. 1973;96:179–87. [PubMed] [Google Scholar]
- 2.Ahmed SM, Ahmad R, Case R, Spencer RF. A study of microbial colonisation of orthopaedic tourniquets. Ann R Coll Surg Engl. 2009;91:131–4. doi: 10.1308/003588409X359402. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Whitehouse JD, Friedman ND, Kirkland KB, Richardson WJ, Sexton DJ. The impact of surgical-site infections following orthopedic surgery at a community hospital and a university hospital: adverse quality of life, excess length of stay, and extra cost. Infect Control Hosp Epidemiol. 2002;23:183–9. doi: 10.1086/502033. [DOI] [PubMed] [Google Scholar]
- 4.Ritter MA. Operating room environment. Clin Orthop. 1999;369:103–9. doi: 10.1097/00003086-199912000-00011. [DOI] [PubMed] [Google Scholar]
- 5.Phillips JE, Crane TP, Noy M, Elliott TS, Grimer RJ. The incidence of deep prosthetic infections in a specialist orthopaedic hospital: a 15-year prospective survey. J Bone Joint Surg Br. 2006;88:943–8. doi: 10.1302/0301-620X.88B7.17150. [DOI] [PubMed] [Google Scholar]
- 6.Fulkerson E, Valle CJ, Wise B, Walsh M, Preston C, Di Cesare PE. Antibiotic susceptibility of bacteria infecting total joint arthroplasty sites. J Bone Joint Surg Am. 2006;88:1231–7. doi: 10.2106/JBJS.E.00004. [DOI] [PubMed] [Google Scholar]
- 7.Rafiq I, Gambhir AK, Wroblewski BM, Kay PR. The microbiology of infected hip arthroplasty. Int Orthop. 2006;30:532–5. doi: 10.1007/s00264-006-0125-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Davis N, Curry A, Gambhir AK, Panigrahi H, Walker CR, et al. Intraoperative bacterial contamination in operations for joint replacement. J Bone Joint Surg Br. 1999;81:886–9. doi: 10.1302/0301-620x.81b5.9545. [DOI] [PubMed] [Google Scholar]
- 9.Nehrer S, Thalhammer F, Schwameis E, Breyer S, Kotz R. Teicoplanin in the prevention of infection in total hip replacement. Arch Orthop Trauma Surg. 1998;118:32–6. doi: 10.1007/s004020050306. [DOI] [PubMed] [Google Scholar]
- 10.Low DE, Willey BM, McGeer AJ. Multidrug-resistant enterococci: a threat to the surgical patient. Am J Surg. 1995;169(Suppl):8S–12S. [PubMed] [Google Scholar]
- 11.Lidwell OM, Lowbury EJ, Whyte W, Blowers R, Stanley SJ, Lowe D. Airborne contamination of wounds in joint replacement operations: the relationship to sepsis rates. J Hosp Infect. 1983;4:111–31. doi: 10.1016/0195-6701(83)90041-5. [DOI] [PubMed] [Google Scholar]
- 12.Blom AW, Barnett A, Ajitsaria P, Noel A, Estela CM. Resistance of disposable drapes to bacterial penetration. J Orthop Surg. 2007;15:267–9. doi: 10.1177/230949900701500303. [DOI] [PubMed] [Google Scholar]