The Use of Antibiograms in Orthopedic Surgery

Clinical impact of microbiological results in two-stage revision arthroplasty with spacer exchange

INTRODUCTION

Patients who require a spacer exchange as part of a two-stage procedure for the treatment of periprosthetic hip and knee joint infections (PJI) have high failure rates. Little is known about the clinical impact of microbiological results and changes in the microbiological spectrum and resistance pattern in these patients.

MATERIAL AND METHODS

Between 01/2011 and 12/2019, 312 patients underwent a total of 327 two-stage revision arthroplasties at our institution. A spacer exchange was required in 52/312 (16.7%) patients (27 knee/25 hip). Microbiological results, antibiotic resistance patterns, patient's host factors as well as re-revision and re-infection rates at a median follow-up of 47.8 months (range 12.2-116.7 months) were analyzed. A propensity score (PS)-matched analysis of patients who underwent spacer exchange and patients treated with standard two-stage procedure was performed.

RESULTS

We found a high number of microbiological spectrum changes in patients with multiple culture positive procedures between explantations and spacer exchanges (10/12 [83.3%]), spacer exchanges and reimplantations (3/4 [75%]) as well as between reimplantations and subsequent re-revision surgeries (5/6 [83.3%]). In 9/52 (17.3%) patients, same microorganisms were detected repeatedly in two different procedures. We observed changes in the antibiotic resistance patterns in 6/9 (66.7%) of these patients. High re-infection rates were found in patients with culture positive reimplantations (10/12 [83.3%]), and low re-infection rates were found in patients with culture negative reimplantations (2/40 [5%]; p < 0.001). Between patients with and without spacer exchange, no differences were found in the re-revision rates (13/52 [25%] with vs. 13/52 [25%] without; p = 1.00) as well as re-infection rates (12/52 [23.1%] with vs. 8/52 [15.4%] without; p = 0.32).

CONCLUSIONS

Changes in microbiological spectrum and antibiotic resistance patterns between stages are common in patients who require a spacer exchange. If eradication of the microorganism at reimplantation can be accomplished, comparable re-revision rates to standard two-stage procedures can be achieved.

Influence of Nutrient Media Compared to Human Synovial Fluid on the Antibiotic Susceptibility and Biofilm Gene Expression of Coagulase-Negative Staphylococci In Vitro

Bacterial antibiotic resistance and biofilm formation are mechanisms usually involved in the pathogeny of implant-related infections. Worldwide, antibiotic susceptibility tests are usually carried out using nutrient-rich media. Clinical routine laboratories and even research centers use for example EUCAST or CLSI for guidelines. In this study, we investigated the effect of different nutrient media on the antibiotic susceptibility and icaADBC gene expression of bacteria in biofilm. As media, Müller-Hinton Bouillon (MHB), Tryptic Soy Broth (TSB) and human synovial fluid (SF) diluted 1:4 in phosphate buffered saline (PBS), each also supplemented with 1% glucose, were used. The influence of different nutrient media on the antibiotic susceptibility of coagulase-negative staphylococci (CoNS) was evaluated by counting of colony-forming units (CFU) and by checking the metabolic activity of the bacteria. We used reverse transcriptase and real-time qPCR to investigate the influence of nutrient media on the biofilm gene expression. We used two-way analysis of variance (ANOVA). p < 0.05 was considered to be statistically significant. Significant differences in growth and antibiotic susceptibility were detected in all strains tested among the different media used. The nutrient media showed influence on the cell viability of all bacteria after antibiotic treatment. IcaADBC gene expression was significantly influenced by glucose and all nutrient media. The results highlight the influence of glucose on the antibiotic susceptibility, growth and gene expression of all strains tested. For all strains, a significant difference in bacterial recovery, viability and gene expression were found when compared to biofilm grown in SF.

Analysis of Culture Positive First and Second Stage Procedures in Periprosthetic Knee and Hip Joint Infections

BACKGROUND

A positive microbiological result at reimplantation may lead to a failed 2-stage revision arthroplasty in the treatment of periprosthetic joint infections. Little is known about changes in microbiological spectrum and resistance pattern between culture positive first and second stage procedures in revision knee and hip arthroplasty.

METHODS

Between January 2011 and December 2019, we performed 327 two-stage revision arthroplasties on 312 patients. There were 37 of 312 (11.9%) patients (20 hips/17 knees) who had a positive microbiological culture during the first and second stage procedure. We analyzed the microbiological spectrum, antimicrobial resistance pattern, and clinical outcome of culture positive first and second stage procedures as well as subsequent re-revisions.

RESULTS

Re-revision was necessary in 40.5% (15/37) of patients with culture positive first and second stage procedure at a median follow-up of 3.5 years. We found microbiological changes in 83.8% (31/37) of patients between the first and second stage and in 88.9% (8/9) between the second stage and subsequent culture positive re-revision. Polymicrobial infections were found in 21.6% (8/37) of first and in 16.2% (6/37) of second stage procedures. In 27% (10/37) of patients, microorganisms persisted between the first and second stage procedure. The antimicrobial resistance pattern changed in 60% of persistent microorganisms between the first and second stage procedure.

CONCLUSION

Changes in microbiological spectrum and resistance pattern are common between culture positive first and second stage procedures as well as subsequent re-revisions. This has to be considered in the antimicrobial treatment of periprosthetic joint infections.

Working towards an ERAS Protocol for Pancreatic Transplantation: A Narrative Review

Enhanced recovery after surgery (ERAS) initially started in the early 2000s as a series of protocols to improve the perioperative care of surgical patients. They aimed to increase patient satisfaction while reducing postoperative complications and postoperative length of stay. Despite these protocols being widely adopted in many fields of surgery, they are yet to be adopted in pancreatic transplantation: a high-risk surgery with often prolonged length of postoperative stay and high rate of complications. We have analysed the literature in pancreatic and transplantation surgery to identify the necessary preoperative, intra-operative and postoperative components of an ERAS pathway in pancreas transplantation.

Device-associated infections in Canadian acute-care hospitals from 2009 to 2018

Background

Healthcare-associated infections (HAIs) pose a serious risk to patient safety and quality of care. The Canadian Nosocomial Infection Surveillance Program (CNISP) conducts national surveillance of HAIs at sentinel acute-care hospitals across Canada. This report provides an overview of 10 years of Canadian data on the epidemiology of select device-associated HAIs.

Methods

Over 40 hospitals submitted data between 2009 and 2018 for hip and knee surgical site infections (SSIs), cerebrospinal fluid shunt SSIs, paediatric cardiac SSIs and/or central line-associated bloodstream infections (CLABSIs). Counts, rates, patient and hospital characteristics, as well as pathogen distributions and antimicrobial susceptibilities are presented.

Results

A total of 4,300 device-associated infections were reported. Central line-associated bloodstream infections were the most common device-associated HAI reported (n=2,973, 69%) and hip and knee arthroplasty infections were the most common SSIs reported (66% of SSIs). Our findings show decreasing CLABSI rates in neonatal intensive care units (4.2 to 1.9 per 1,000 line-days, p<0.0001) and decreasing knee SSI rates (0.69 to 0.30 infections per 100 surgeries, p=0.007). Rates of device-associated HAIs have remained relatively consistent over the 10-year surveillance period. Overall, 4,599 pathogens were identified from device-associated HAI; 70% of these were related to CLABSIs. Coagulase-negative staphylococci (29%) and Staphylococcus aureus (14%) were the most frequently reported pathogens. Gram-positive pathogens represented 68% of identified pathogens, gram-negative pathogens represented 22% and fungi represented 9%.

Conclusion

Understanding the national burden of device-associated HAIs is essential for developing and maintaining benchmark rates for informing infection and prevention control and antimicrobial stewardship policies and programs.

Nationwide Organism Susceptibility Patterns to Common Preoperative Prophylactic Antibiotics: What Are We Covering?

BACKGROUND

Many periprosthetic joint infections (PJIs) are caused by organisms not susceptible to first-generation cephalosporins. We sought to evaluate the national susceptibility patterns of organisms to cefazolin and, or oxacillin, clindamycin, and vancomycin using antibiogram data.

METHODS

Publically available regional and state antibiograms were evaluated for antibiotic susceptibility patterns to commonly infecting gram-positive organisms. The number of isolates tested in each antibiogram and percent of strains susceptible to oxacillin, clindamycin, and vancomycin were recorded. Oxacillin is used as a surrogate to cefazolin in antibiograms. A comparison of antibiotic susceptibilities was performed.

RESULTS

Seven state and 38 regional antibiograms were reviewed. Oxacillin was a sensitive antibiotic in 99.2 ± 4.8% of methicillin-sensitive Staphylococcus aureus (MSSA) isolates, 0 ± 0% of methicillin-resistant Staphylococcus aureus (MRSA) isolates, 44.5 ± 13.7% of coagulase-negative staphylococcus organism isolates (CNS), and 30.6 ± 10.5% of Staphylococcus epidermidis isolates. Clindamycin was a sensitive antibiotic in 75.8 ± 8.4% of MSSA isolates, 60.2 ± 13.2% of MRSA isolates, 60.3 ± 11.4% of CNS isolates, and 56.2 ± 6.5% of S epidermidis isolates. Vancomycin was a sensitive antibiotic in 99.9 ± 0.4% of MSSA isolates, 99.8 ± 0.4% of MRSA isolates, 99.8 ± 0.5% of CNS isolates, and 99.6 ± 0.7% of S epidermidis isolates. Clindamycin was significantly less sensitive in MSSA isolates as compared with oxacillin and vancomycin (P < .0001). Oxacillin was significantly less sensitive in CNS, S epidermidis, and MRSA isolates as compared with clindamycin and vancomycin (P < .0001).

CONCLUSION

The national clindamycin susceptibility pattern is limited to MSSA and may not have an optimal susceptibility profile suitable for use as a prophylactic antibiotic. Cefazolin continues to have excellent coverage against MSSA.