Single-stage revision for total shoulder arthroplasty infection. Results at a minimum 2 years follow-up

A nine-year retrospective study of bacterial epidemiology and culture optimization in four orthopaedic surgery departments

BACKGROUND

Management of device-associated bone and joint infections combines surgical treatment and antibiotic therapy. Immediate postoperative broad-spectrum empiric treatment is often recommended pending complete microbiology results. The probabilistic antibiotics often used are not harmless, and expose the patient to the selection of resistant bacteria and changes in bacterial ecology within the healthcare units. The aim of this study was to answer the following questions: (1) Have the pathogenic bacteria isolated in osteoarticular infections and/or their antibiotic susceptibility profile changed over a 9-year period at our center, with possible implications for antibiotic therapy protocols? (2) Is there a way to optimize the incubation time for microbiological cultures while still being acceptable for slow growing pathogens?

HYPOTHESIS

Our hypothesis was that no difference in microbial epidemiology and antibiotic resistance rates would be found over this 9-year period, confirming antibiotic protocols.

MATERIALS AND METHODS

We conducted a retrospective study describing a nine-year bacterial epidemiology in four traumatology and orthopedic surgery departments. Bacteria identified, site of infection, and antibiotic resistance were evaluated. Antibiotics for use in probabilistic protocols and after documentation of infection were selected for follow-up. Bacterial species were isolated after a maximum incubation period of 15 days up to 2020, and 10 days from 2021 with the addition of a solid culture medium that promotes anaerobic bacterial growth.

RESULTS

Of the 648 clinical situations, 824 bacteria were identified. Gram-positive cocci accounted for 61.4% (506/824) of the strains, including 291/824 (35.3%) Staphylococcus aureus and 136/824 (16.5%) coagulase-negative staphylococci. For the latter, fluoroquinolone resistance remained stable at 7.3% (18/291 (p = 0.086)) and 22.8% (34/136 (p = 0.432)), respectively. Resistance to rifampicin was also stable for Staphylococcus aureus (1.2%,4/291 (p = 0.486)) and for coagulase-negative staphylococci (10.7%, 15/136 (p = 0.596)). Enterobacteriaceae accounted for 148/824 (18.0%) of identifications and were more resistant to piperacillin/tazobactam (15.1%, 24/148) than to cefepime (5.6%,9/148 (p = 0.006)). There was no significant difference between the 15-day and 10-day culture protocols in the proportion of anaerobic bacteria isolated from shoulder (p = 0.721), hip and knee (p = 0.530) prosthesis infections and spinal device-associated infections (p = 0.373). A microbiological diagnosis was made within five days using the 10-day culture protocol in 333/344 (96.8%) cases.

DISCUSSION

The increase in Cutibacterium acnes isolates is mainly explained by the increased number of patients recruited for shoulder arthroplasty. No change in antibiotic resistance was observed in our retrospective study. This is probably related to the use of some precautions when prescribing antibiotic therapy. For gram-negative bacilli, cefepime is the beta-lactam of choice for probabilistic treatment when combined with an antibiotic that is particularly effective against methicillin-resistant staphylococci. An incubation period limited to 10 days seems to be sufficient for the culture of slow-growing organisms, as epidemiological analysis has not shown any negative effects.

LEVEL OF EVIDENCE

Level IV. Retrospective cohort study.

Comparative performance analysis of Synovasure™ and Leukocyte Esterase assays for the diagnosis of periprosthetic infections in complex microbiological situations

INTRODUCTION

Osteoarticular infections (OAI) after prosthetic surgery have serious functional and economic consequences. Rapid tests for alpha-defensin (TAD) and leukocyte esterase (TLE) are two intra-articular markers involved in the diagnosis of OAIs. TLE cannot be applied in the presence of blood unless centrifugation is used, but the rate of "non-application" of the test for this reason is unknown in complex microbiological situations (discordant or negative puncture, ongoing antibiotic treatment). We therefore conducted a prospective study to determine: 1) the performance of the TAD and TLE rapid tests in diagnosing complex OAI, 2) the rate of non-application of the TLE due to hemarthrosis, and 3) the concordance between the two tests.

ASSUMPTION

These two diagnostic tests had a negative predictive value (NPV) ≥ 90% for the diagnosis of complex OAI.

MATERIALS AND METHODS

A total of 79 suspected OAI patients with complex microbiological diagnoses were included between 2018 and 2023. They were 52 men (66%) for 27 women (34%), with a mean age of 66 ± 13.5 years. The hip (n = 41, 52%) and knee (n = 36, 46%) were the most represented, followed by the elbow (n = 1, 1%) and shoulder (n = 1, 1%). These patients were suspected of having an OAI that required joint puncture, but with a complex microbiological diagnosis due to discordant punctures (n = 21, 27%) or sterile punctures despite strong suspicion of infection (n = 50, 63%), or in case of ongoing antibiotic treatment (n = 8, 10%). All patients underwent joint fluid puncture followed by TAD (Synovasure™, Zimmer, Warsaw, IN, USA) and, when the macroscopic appearance of the sample allowed (clear fluid group), TLE (Multistix 8SG, Siemens Healthcare GmbH, Erlangen, Germany). The results of both tests were compared with Musculoskeletal Infection Society (MSIS) criteria.

RESULTS

Of the 79 patients included, 27 (34%) were considered infected according to the MSIS. In 30% of cases (n = 24), TLE was not feasible due to the presence of blood in the joint fluid. In the "clear fluid" group, the NPV was equal to 90% for both TAD (sensitivity 87%, specificity 88%) and TLE (sensitivity 87%, specificity 81%). The two parameters showed almost perfect agreement (κ = 0.927).

CONCLUSION

TAD and TLE are two rapid, reliable tests with near-perfect concordance and high NPV, even in situations of complex microbiological diagnosis. They are particularly useful for deciding on a therapeutic strategy for patients with complex OAI. The TLE cannot be used in 30% of cases due to hemarthrosis, but centrifugation can correct this defect.

LEVEL OF EVIDENCE

III; Prospective comparative diagnostic accuracy study.

Management of periprosthetic joint infection of the shoulder: A narrative review

Evidence for management of shoulder periprosthetic joint infection (PJI) has traditionally originated from the hip and knee literature. The differing microbiome, anatomy and implants used in the shoulder mean this evidence is not always directly transferrable. The 2018 Philadelphia International Consensus Meeting for the first-time produced evidence-based guidelines and diagnostic criteria relating specifically to PJI of the shoulder. These guidelines and criteria recognize the pathogenicity of lower virulence organisms in the shoulder which often means clinical presentation is less obvious than other joints. The role of Cutibacterium acnes in shoulder PJI is the subject of increasing basic science and clinical research and advances in microbiological research may help to understand the pathology behind shoulder infections. There is new evidence that outcomes after revision shoulder arthroplasty are dependent on the virulence of the causative organism. An individualised approach to treatment considering host factors, organism, soft tissues and bone stock is recommended. Debate continues in the literature regarding the indications of one- or two-stage revision and the latest evidence is discussed and synthesized in this review article. We advocate careful multidisciplinary team decision making for cases of shoulder PJI and recognize a limited role for debridement and implant retention in acute shoulder PJI (<6 weeks). There appears to be a role for one-stage revision in lower risk cases with low virulence organisms but caution against its' universal adoption. In higher risk or complex cases, there remains a clear role for two-stage revision arthroplasty, and we detail the specifics of this protocol and procedure from our tertiary shoulder and elbow unit.