Evaluation of factors associated with surgical site infection in equine proximal interphalangeal joint arthrodesis: 54 cases (2010–2019)

Background

The frequency of surgical site infection (SSI) following orthopaedic implant placement in horses has been reported but not compared with respect to specific antibiotic protocols administered.

Objectives

To determine factors associated with SSI in horses undergoing proximal interphalangeal joint (PIPJ) arthrodesis including perioperative antibiotic protocols.

Methods

Records were evaluated (2010–2019), and horses undergoing PIPJ arthrodesis were identified. Patient signalment, supervising surgeon, reason for surgery, limb, implants placed, anaesthetic time, duration casting/coaptation postoperatively, antibiotic regimen and incidence/onset SSI were recorded. Bayesian and frequentist logistic regressions were used to estimate the contribution of covariates to infection occurrence.

Results

Fifty‐four PIPJ arthrodeses were performed. SSI occurred in 2/54 (3.7%) on day 15,30. Arthrodesis was performed most commonly for osteoarthritis (33/54, 61.1%), fracture (11/54, 20.4%), and subluxation (5/54, 9.3%). Perioperative systemic antibiotics were administered 1–3 days (15/54, 27.8%) or > 3 days (39/54, 72.2%). Antibiotic protocols included cefazolin/gentamicin (20/54, 37%), cefazolin/gentamicin/doxycycline (14/54, 25.9%) and potassium penicillin/gentamicin (10/54, 18.5%). Regional limb perfusion was performed preoperatively 31/54 (57.4%) and postoperatively 7/54 (13%). Survival to dismissal was 98.1% (53/54 horses) with one horse euthanized due to support limb laminitis. No association was identified between antibiotic selection or duration (1–3 vs. > 3 days), pre‐operative regional antibiotic perfusion, intraoperative antibiotic lavage or anaesthetic time (< or > 3 h) and SSI; however, modelling was complicated by quasi‐complete or complete separation of the data. Bayesian analysis (but not frequentist analysis) indicated an association between post‐operative regional antibiotic perfusion and SSI. Limitations include the retrospective nature of data collection and the low rate of infection overall.

Conclusions

The prevalence of SSI in this population was lower than that in previous reports of equine orthopaedic internal fixation. There was no difference in SSI rate in cases administered systemic antibiotics for 1–3 days or >3 days, or for those horses that did or did not receive preoperative regional antibiotic perfusion.

A scoping review of the current evidence on treatment and outcomes following synovial sepsis

BACKGROUND

Synovial sepsis is a frequent cause of morbidity and mortality in horses. Despite advances in diagnostics and treatments, persistent infection or chronic lameness can occur.

OBJECTIVES

To perform a scoping review to identify and evaluate the current evidence on the factors implicated in the success of treatment for synovial sepsis.

STUDY DESIGN

Joanna Briggs Institute scoping review.

METHODS

A protocol was registered, and a systematic literature search was performed on CAB abstracts, Medline, Scopus and Embase. Inclusion and exclusion criteria were developed and studies systematically reviewed against this. Studies relating to factors affecting treatment success following synovial sepsis were retained and data was extracted on study method, population characteristics and factors significantly associated with treatment outcome.

RESULTS

In total, 2338 studies were identified, and 61 were included to full paper analysis. Eight papers reported significant factors, identifying 15 risk factors associated with two measurements of outcome, either survival and/or return to athletic function. The 15 factors were identified and categorised into pre-, intra- and post-operative factors. Risk factors that were identified included the number or type of synovial structures involved, the presence of pannus, tendon and bone pathology, and the use of systemic antimicrobials. There were many discrepancies in inclusion criteria of cases of synovial sepsis as well as measurement and description of outcome variables.

MAIN LIMITATIONS

Non-English language studies or conference proceedings were not included. Only small numbers of papers had similar findings.

CONCLUSIONS

Standardisation of inclusion criteria is essential to enable comparisons and analysis between studies on synovial sepsis. Future studies should use methodologies to reduce bias including multicentre and multinational studies, prospective study design and robust statistical modelling.

Usefulness of Selected Acute-Phase Proteins in the Postsurgical Monitoring of Arthroscopy and Splint Bone Removal in Horses

Simple Summary

The study shows the changes in concentration of acute phase proteins (fibrinogen, haptoglobin, protease inhibitors) in the serum of patients from the equine clinic. Blood was collected from horses that underwent arthroscopy (41 horses) and splint bone removal (13 horses). The concentration of the above-mentioned proteins was recorded from the time before the surgery until the 28th day after the surgery and compared to a control group of healthy horses (60 horses). Acute phase proteins change their concentration before clinical symptoms appear; therefore, they could play a key role in early recognition and preventing complications.

Abstract

Background: Arthroscopy and splint bone removal are the common orthopedic procedures in horses. Estimation of the dynamics of acute phase proteins in postoperative monitoring seems to be interesting diagnostic approach. The aim of the study was to investigate changes in the concentrations of plasma inflammatory markers—fibrinogen, haptoglobin, and protease inhibitors—following orthopedic surgery in horses. The study involved 114 horses, divided into two study groups undergoing: arthroscopy (41 horses) and splint bone removal (13 horses). The control group consisted of 60 healthy horses. The blood was collected before the surgery and 24, 48, 72 h, 5, 7, 10, 14 and 28 days after the surgery. Plasma fibrinogen, serum haptoglobin and proteinase inhibitors were measured. Results: In non-complicated cases of arthroscopy and splint bone removal, fibrinogen and haptoglobin increased stepwise from 24 h, achieved the maximum level at 72 h and returned to preoperative levels after 10–14 days. In one complicated case after arthroscopy surgery the marked increase in fibrinogen and haptoglobin concentrations was observed 24 h earlier than standard parameters of inflammation Conclusion: The study shows the evolution of APPs after arthroscopy and splint bone removal in 28 days postsurgery period and in the case of one complicated case of arthroscopy.

Antimicrobial Effects of Equine Platelet Lysate

The development of antimicrobial resistant bacteria and the lack of novel antibiotic strategies to combat those bacteria is an ever-present problem in both veterinary and human medicine. The goal of this study is to evaluate platelet lysate (PL) as a biological alternative antimicrobial product. Platelet lysate is an acellular platelet-derived product rich in growth factors and cytokines that is manufactured via plateletpheresis and pooled from donor horses. In the current study, we sought to define the antimicrobial properties of PL on select gram-positive and gram-negative bacteria. Results from an end-point in vitro assay showed that PL did not support bacterial growth, and in fact significantly reduced bacterial content compared to normal growth media. An in vitro assay was then utilized to further determine the effects on bacterial growth dynamics and showed that all strains exhibited a slower growth rate and lower yield in the presence of PL. The specific effects of PL were unique for each bacterial strain: E. coli and P. aeruginosa growth was affected in a concentration-dependent manner, such that higher amounts of PL had a greater effect, while this was not true for S. aureus or E. faecalis. Furthermore, the onset of exponential growth was delayed for E. coli and P. aeruginosa in the presence of PL, which has significant clinical implications for developing a dosing schedule. In conclusion, our findings demonstrate the potential value of PL as a broad-spectrum antimicrobial that would offer an alternative to traditional antibiotics for the treatment of bacterial infection in equine species.

Retrospective evaluation of association between perioperative antimicrobial protocol and complications following elective equine synovial endoscopy

Background

Prophylactic perioperative antimicrobial protocols in equine synovial endoscopy have been described but not compared with respect to post‐operative outcomes and complications. Increasing antimicrobial resistance in equine practice and interest in promoting judicious use of antimicrobials has prompted reevaluation of drug selection and dosing strategies.

Objectives

To determine the frequency of and compare post‐operative complications following elective synovial endoscopy between horses receiving different perioperative antimicrobial protocols.

Methods

Records from the Colorado State University Veterinary Teaching Hospital were evaluated (2014–2018) and equine patients undergoing elective synovial endoscopy were identified. Patients undergoing endoscopy for sepsis or internal fixation were excluded. Patient signalment, clinician, joint and limb involved, perioperative antimicrobial regimen, number endoscopic portals and closure technique, and post‐operative complications including incidence of joint infection were recorded. Generalized linear models were used to estimate the odds of post‐operative complications.

Results

Elective synovial endoscopies of 516 horses in 537 procedures evaluating 761 synovial structures were performed. No horses developed post‐operative septic synovitis. Administration of post‐operative antimicrobials, type used and patient sex were all significantly associated with increased risk of complications, which were predominantly gastrointestinal‐related. Complication rates in horses receiving a single preoperative dose of cefazolin were lower than in horses receiving potassium penicillin, gentamicin or multiple doses. Complication rates were lower in females compared to castrated or intact males. Other factors evaluated (breed, age, surgeon, anaesthesia duration or hospitalization, joint/limb operated, number endoscopic portals) were not associated with increased risk of complications post‐operatively in this case population.

Conclusions

Prophylactic perioperative antimicrobial protocols in equine practice deserve periodic reconsideration due to increased antimicrobial resistance. Prolonged antimicrobial usage beyond the time of surgery was unnecessary to prevent septic synovitis following synovial endoscopy in this case population and was furthermore associated with an increased risk of gastrointestinal complications.

Antimicrobial prescribing patterns of clinicians and clinical services at a large animal veterinary teaching hospital

OBJECTIVE

To characterize antimicrobial prescribing patterns of clinicians and clinical services at a large animal veterinary teaching hospital and identify factors associated with antimicrobial prescribing.

ANIMALS

All large animals (ie, equids, bovids, sheep, goats, camelids, swine, and cervids) evaluated at the New Bolton Center hospital at the University of Pennsylvania from 2013 through 2018.

PROCEDURES

In a cross-sectional study design, data on antimicrobial use by clinicians and clinical services were collected from administrative and billing records. Multivariable regression modeling was performed to identify factors associated with antimicrobial prescribing patterns.

RESULTS

Antimicrobials and critically important antimicrobials of the highest priority were dispensed in 42.1% (9,853/23,428) and 24.0% (2,360/9,853) of visits, respectively, and these proportions differed significantly among clinicians. Per visit, the median (interquartile [25th to 75th percentile] range) number of animal-defined daily doses dispensed was 3.6 (0.8 to 11.1) and the mean (SD) number of antimicrobial classes dispensed was 2.0 (1.3). Patient species, age, affected body system, and duration of hospitalization as well as submission of specimens for bacterial culture were significantly associated with prescribing patterns.

CONCLUSIONS AND CLINICAL RELEVANCE

The frequency and quantity of antimicrobials prescribed differed significantly among clinicians within and across services, even for animals with clinical signs affecting the same body system. Patient- and visit-level factors explained some but not all of the heterogeneity in prescribing patterns, suggesting that other clinician-specific factors drove such practices. More research is needed to better understand antimicrobial prescribing patterns of clinicians, particularly in situations for which no antimicrobial use guidelines have been established.

Retrospective assessment of perioperative antimicrobial use for elective arthroscopy in horses

OBJECTIVE

To describe perioperative antimicrobial use in horses undergoing elective arthroscopy.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Horses that underwent elective arthroscopy at one institution between July 2016 and May 2018, excluding those with a suspected infectious orthopedic disease or with a comorbidity that may have impacted prophylactic antimicrobial use decisions.

METHODS

Medical records were reviewed to evaluate preoperative, intraoperative, and postoperative antimicrobial drug selection, dose, and timing. Associations between body weight and underdosing were evaluated by using analysis of variance, χ² test was used for categorical comparisons, and least squares fit was used to evaluate factors associated with duration of postoperative antimicrobials.

RESULTS

Among 150 horses, 149 (99.3%) received systemic preoperative antimicrobials. Only 53 (40.2%) horses were administered doses within 60 minutes of surgical incision. First incision was performed more than two half-lives after administration of sodium penicillin in 46 of 131 (35.1%) horses but in only 1 of 106 (0.8%) horses that received trimethoprim-sulfadoxine. Body weight was associated with underdosing for penicillin (P = .0075) and trimethoprim-sulfadoxine (P = .002) but not gentamicin (P = .92). Twenty-six (17%) horses received one postoperative antimicrobial dose, while antimicrobials were continued in hospital for a mean of 22.3 ± 4.4 hours after surgery in the other 123 horses. Among the 149 discharged horses, 115 (77.2%) were prescribed antimicrobials after discharge (range, 3-10 days; median, 3 days, interquartile range, 0 days).

CONCLUSION

Deviations from common recommendations were apparent and provide evidence for the requirement to develop interventions to optimize perioperative prophylaxis.

CLINICAL SIGNIFICANCE

Perioperative antimicrobial use practices should be regularly assessed to provide a benchmark and identify areas for intervention.

Surgical site infection associated with equine orthopedic internal fixation: 155 cases (2008-2016)

OBJECTIVE

To determine the prevalence of surgical site infection (SSI) after internal fixation and to identify risk factors for SSI and nonsurvival.

STUDY DESIGN

Retrospective study.

ANIMALS

One hundred fifty-five horses with long bone fractures or arthrodesis treated by internal fixation at 1 hospital between 2008-2016.

METHODS

Signalment, diagnosis, surgical repair, surgeon, surgical time, antimicrobial use, SSI onset, bacterial identification, and adjunct treatments were recorded. Perioperative variables were analyzed to identify risk factors associated with outcomes.

RESULTS

Surgical-site infection was reported in 22 of 155 (14.2%) horses, which is lower than what has been previously reported (P = .003). Horses with fetlock arthrodesis or ulnar fracture were more likely to develop SSI. Local prophylactic antimicrobial therapy was associated with an increased risk of SSI. Horses with SSI were 12 times (P < .0001) less likely to survive to discharge than horses without SSI. Horses with a fetlock or carpal arthrodesis or those with radial/humeral/femoral fractures were less likely to survive. No association was identified between open fractures, open reduction and internal fixation, or surgical times and SSI.

CONCLUSION

The prevalence of SSI in this population was lower than what has been previously reported. Horses with fetlock or carpal arthrodesis or radial/humeral/femoral fractures were at increased risk for SSI and/or nonsurvival to discharge. A protective role of local antimicrobial therapy for SSI could not be established.

CLINICAL RELEVANCE

The impact of SSI on outcomes of cases of equine internal fixation remains substantial. Identification of cases at higher risk of SSI should influence surgical technique, postoperative management, and early intervention when SSI is suspected. Additional investigation is warranted regarding local antimicrobial therapy.