The Spectrum of Infective Organisms in Orthopaedic Surgery in Queensland – Geographic and Temporal Trends

Prosthesis related infection is one of the most dreaded complications in orthopaedics. Infections occur at significant rates for arthroplasty (e.g. 0.8%–1.2% for TKR/THR) and after compound fractures 1.  They represent a challenging problem and burden in terms of morbidity, mortality and cost. There are concerns of increasing antimicrobial resistance across the health sector, this could have a huge impact on the practice of orthopaedic surgery. Understanding in detail and tracking any changes over time are paramount to planning treatment and prevention – that may be locality specific. Bacterial culture and sensitivity analysis is a process that takes days, and we are often left using empirical antibiotics that may not be sensitive for the offending organism.

Data from the AOA Joint Registry demonstrates primary arthroplasties for the hip, knee and shoulder continue to increase year on year. The latest report analysed over a million combined TKR, THR and TSR procedures from the last decade. There were over 100,00 cases in the last year 2, almost 60 000 total knee arthroplasties and 40 000 total hips (Table 1). The report published data for almost 10 000 revision cases due to infection. Various groups across Australia have estimated the cost of prosthetic joint infection, taking into account extended patient stay, theatre and implant costs.  Peter Choong 3 and others estimated the cost of an infected prosthetic hip at around $70 000 and a local team working with Prof Crawford estimated cost of TKR infection $13-7000 depending on 1, 2 stage DAIR 4, shoulder replacement data is extrapolated from US 5. These graphs (Figure 1) demonstrate the cumulative revision rate for infection approaches 1% for knee, hip and shoulder arthroplasty.

Queensland has a wide variety of climates over its geographical regions (Figure 2). There is also local research looking into regional patterns of infection in arthroplasty. Dr Ben Parkinson and Drew Armit investigated the association between revision for prosthetic joint infection and climate 6. They analysed over 200 000 registry patients and showed tropical regions had twice the rate of early revision, and that the rate of revision was double in the wet season compared to dry. In another paper analysing all cases in Cairns hospital over 13 years they suggested -humidity and ambient temperature would be potentially important risk factors in total knee prosthetic joint infection 7. A further paper analysing over 800 microbial swabs after surgery demonstrated differences in tropical regions which were more likely to culture multi drug resistant and non-fermenters such as pseudomonas and acinobacter 8.

The Prosthetic Joint Infection in Australia and New Zealand, Observational (PIANO) Study study is a large ID lead prospective study of prosthetic joint infection documenting clinical presentation, management and outcomes 9. They have written about almost 800 patients with prosthetic joint infection but have not specially published on resistance profiles or geographic trends.

The idea of this study is that there may be differences in the patters of infective organisms over geographic areas and different climates in Queensland, and that antimicrobial resistance may be increasing over time – with an increasing predominance of multi drug resistant organisms. This is something that has not been thoroughly investigated in the literature.

Queensland health is in a unique position in Australia and even globally – with a common pathology and electronic healthcare records systems in the public sector over the entire state. All pathology is stored on a central database with capabilities for bulk export. There are various business enterprise reporting software systems built into the electronic health records that are used for health econometrics. There databases are operated and run by different bodies within the health sectors. There are immense possibilities for data export, linkage and analysis for academic research and to improve patient care. The combination of surgical operation details, and microbiology results will allow the study of infective organisms in surgery.

This is retrospective multi-site epidemiological study that aims to assess all prosthetic joint infections operated in Queensland public health system from 2010-2020 for hip knee and shoulder arthroplasty. This will be done by linking databases that store information on operative records with pathology services that store results of microbial culture. Analysis for microbe, sensitivity panel, geographic location, temperature and humidity.

This study is likely to be the largest published on orthopaedic hardware infections in Australia.  This has the potential to promote evidence based orthopaedic practice in the treatment of orthopaedic infections. Infection and sensitivities may differ based on anatomical or geographic location. The results have the potential to influence local and state-based guidelines and improve care for the treatment of implant related infection, which is a significant cost in terms of morbidity, mortality and hospital resources. It may highlight concerns for increasing trends in antimicrobial resistance over time and indicate different treatment strategies for different locations. This will also provide a framework that could be developed for real time monitoring, and regular reporting prospectively of infections in orthopaedics.

References:

1.           Koh CK, Zeng I, Ravi S, Zhu M, Vince KG, Young SW. Periprosthetic Joint Infection Is the Main Cause of Failure for Modern Knee Arthroplasty: An Analysis of 11,134 Knees. Clin Orthop Relat Res. 2017 Sep;475(9):2194-201. Epub 2017/06/03.

2.           AOA. Australian Orthopaedic Association National Joint Replacement Registry

(AOANJRR): Hip, Knee & Shoulder Arthroplasty Annual Report. Adelaide: 2020.

3.           Peel TN, Dowsey MM, Buising KL, Liew D, Choong PF. Cost analysis of debridement and retention for management of prosthetic joint infection. Clin Microbiol Infect. 2013 Feb;19(2):181-6. Epub 2012/01/24.

4.           Merollini KM, Crawford RW, Graves N. Surgical treatment approaches and reimbursement costs of surgical site infections post hip arthroplasty in Australia: a retrospective analysis. BMC Health Serv Res. 2013 Mar 11;13:91. Epub 2013/03/19.

5.           Baghdadi YMK, Maradit-Kremers H, Dennison T, Ransom JE, Sperling JW, Cofield RH, et al. The hospital cost of two-stage reimplantation for deep infection after shoulder arthroplasty. JSES Open Access. 2017 Mar;1(1):15-8. Epub 2017/04/19.

6.           Parkinson B, Armit D, McEwen P, Lorimer M, Harris IA. Is Climate Associated With Revision for Prosthetic Joint Infection After Primary TKA? Clin Orthop Relat Res. 2018 Jun;476(6):1200-4. Epub 2018/02/23.

7.           Armit D, Vickers M, Parr A, Van Rosendal S, Trott N, Gunasena R, et al. Humidity a potential risk factor for prosthetic joint infection in a tropical Australian hospital. ANZ J Surg. 2018 Dec;88(12):1298-301. Epub 2018/10/26.

8.           Vickers ML, Ballard EL, Harris PNA, Knibbs LD, Jaiprakash A, Dulhunty JM, et al. Bacterial Profile, Multi-Drug Resistance and Seasonality Following Lower Limb Orthopaedic Surgery in Tropical and Subtropical Australian Hospitals: An Epidemiological Cohort Study. Int J Environ Res Public Health. 2020 Jan 20;17(2). Epub 2020/01/24.

9.           Manning L, Metcalf S, Clark B, Robinson JO, Huggan P, Luey C, et al. Clinical Characteristics, Etiology, and Initial Management Strategy of Newly Diagnosed Periprosthetic Joint Infection: A Multicenter, Prospective Observational Cohort Study of 783 Patients. Open Forum Infect Dis. 2020 May;7(5):ofaa068. Epub 2020/05/21.