Locally-administered antibiotics in wounds in a limb

Does the Application of Topical Vancomycin Reduce Surgical Site Infections in Spine Surgery? A Meta-analysis of Randomized Controlled Trials

BACKGROUND

Surgical site infections (SSIs) represent a major challenge in spine surgery, leading to severe morbidity, mortality, and increased costs. The local application of antibiotics, particularly vancomycin, has emerged as a potential strategy. Individual randomized controlled trials (RCTs) have disagreed about the efficacy of topical vancomycin in preventing SSIs after spine surgery, and so a meta-analysis that pools data from those RCTs might be helpful to inform clinicians' decisions on the topic.

QUESTIONS/PURPOSES

This meta-analysis of RCTs asked: Does intrawound topical vancomycin reduce the risk of (1) SSIs, (2) deep SSIs, and (3) superficial SSIs in patients undergoing spine surgery?

METHODS

PubMed, Cochrane, and Google Scholar (pages 1-20) were searched up through March 13, 2024 (search performed on March 13, 2024). Inclusion criteria consisted of English or non-English-language RCTs comparing the implementation of topical vancomycin in spine surgery to its nonuse and assessing its efficacy in preventing SSI, while exclusion criteria consisted of nonrandomized comparative studies, single-arm noncomparative studies, comparative studies based on national databases or from the same center as other included studies, studies posted to preprint servers, studies reporting incomplete/nonrelevant outcomes, and studies adding another SSI preventive measure. The studies were assessed using the Cochrane Risk of Bias tool. Heterogeneity was evaluated by Q tests and I2 statistics. We used a random-effects model when considerable heterogeneity was observed (all SSIs, deep SSIs); otherwise, a fixed-effects model was used (all SSIs subanalysis, superficial SSIs). Furthermore, the fragility index was calculated for each of the assessed outcomes when there was no difference between the two groups to assess how many patients were needed to experience the outcomes for a difference to become present. The studied outcomes were the risks of SSIs, deep SSIs, and superficial SSIs. Deep SSIs were defined by the included trials as SSIs underneath the fascia, otherwise they were considered superficial. Six RCTs representing a total of 2140 patients were included, with 1053 patients in the vancomycin group and 1087 in the control group. Using an alpha of 0.05, our meta-analysis had 80% power to detect a risk difference of 1.5% for the primary outcome between patients who did and did not receive vancomycin. The age of the patients in the vancomycin group ranged from 37 to 52 years, while the age in the control group ranged from 34 to 52 years. The surgical procedures consisted of both instrumented and noninstrumented spinal procedures. Overall, the risk of bias in the included studies was either low or unclear, with none of the studies having a high risk of bias in any of the assessed categories (selection bias, performance bias, detection bias, attrition bias, and reporting bias).

RESULTS

We found no difference in the risk of SSI between the vancomycin and control groups (3.0% [32 of 1053] versus 3.9% [42 of 1087], relative risk 0.74 [95% CI 0.35 to 1.57]; p = 0.43). Ten additional patients (4.8% infection risk) in the control group would need to experience an SSI for a difference to be observed between the two groups. We found no difference in the risk of deep SSI between the vancomycin and control groups (1.8% [15 of 812] versus 2.7% [23 of 860], relative risk 0.69 [95% CI 0.24 to 2.00]; p = 0.50). Seven additional patients (3.5% infection risk) in the control group would need to experience a deep SSI for a difference to be observed between the two groups. We found no difference in the risk of superficial SSI between the vancomycin and control groups (1.0% [6 of 620] versus 1.4% [9 of 662], relative risk 0.68 [95% CI 0.25 to 1.89]; p = 0.46). Seven additional patients (2.4% infection risk) in the control group would need to experience a superficial SSI for a difference to be observed between the two groups.

CONCLUSION

This meta-analysis of randomized trials examining use of topical vancomycin in spine surgery failed to show efficacy in reducing infection, and thus we do not recommend routine use of topical vancomycin for this indication. Future large-scale trials would be needed if surgeons believe that between-group differences smaller than those for which we were powered here (this meta-analysis had 80% power to detect a between-group difference of 1.5% in infection risk) are clinically important, and large database surveys may be informative in terms of assessing for postoperative adverse events associated with the use of vancomycin powder.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Choosing the right animal model for osteomyelitis research: Considerations and challenges

Osteomyelitis is a debilitating bone disorder characterized by an inflammatory process involving the bone marrow, bone cortex, periosteum, and surrounding soft tissue, which can ultimately result in bone destruction. The etiology of osteomyelitis can be infectious, caused by various microorganisms, or noninfectious, such as chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO). Researchers have turned to animal models to study the pathophysiology of osteomyelitis. However, selecting an appropriate animal model that accurately recapitulates the human pathology of osteomyelitis while controlling for multiple variables that influence different clinical presentations remains a significant challenge. In this review, we present an overview of various animal models used in osteomyelitis research, including rodent, rabbit, avian/chicken, porcine, minipig, canine, sheep, and goat models. We discuss the characteristics of each animal model and the corresponding clinical scenarios that can provide a basic rationale for experimental selection. This review highlights the importance of selecting an appropriate animal model for osteomyelitis research to improve the accuracy of the results and facilitate the development of novel treatment and management strategies.

Mid- to long-term results of single-stage surgery for patients with chronic osteomyelitis using a bioabsorbable gentamicin-loaded ceramic carrier

AIMS

Excision of chronic osteomyelitic bone creates a dead space which must be managed to avoid early recurrence of infection. Systemic antibiotics cannot penetrate this space in high concentrations, so local treatment has become an attractive adjunct to surgery. The aim of this study was to present the mid- to long-term results of local treatment with gentamicin in a bioabsorbable ceramic carrier.

METHODS

A prospective series of 100 patients with Cierny-Mader Types III and IV chronic ostemyelitis, affecting 105 bones, were treated with a single-stage procedure including debridement, deep tissue sampling, local and systemic antibiotics, stabilization, and immediate skin closure. Chronic osteomyelitis was confirmed using strict diagnostic criteria. The mean follow-up was 6.05 years (4.2 to 8.4).

RESULTS

At final follow-up, six patients (six bones) had recurrent infection; thus 94% were infection-free. Three infections recurred in the first year, two in the second year, and one 4.5 years postoperatively. Recurrence was not significantly related to the physiological class of the patient (1/20 Class A (5%) vs 5/80 Class B (6.25%); p = 0.833), nor was it significantly related to the aetiology of the infection, the organisms which were cultured or the presence of nonunion before surgery (1/10 with nonunion (10%) vs 5/90 without nonunion (5.6%); p = 0.570). Organisms with intermediate or high-grade resistance to gentamicin were significantly more likely in polymicrobial infections (9/21; 42.8%) compared with monobacterial osteomyelitis (7/79 (8.9%); p < 0.001). However, recurrence was not significantly more frequent when a resistant organism was present (1/16 for resistant cases (6.25%) vs 5/84 in those with a microbiologically sensitive infection (5.95%); p = 0.958).

CONCLUSION

We found that a single-stage protocol, including the use of a high-delivery local antibiotic ceramic carrier, was effective over a period of several years. The method can be used in a wide range of patients, including those with significant comorbidities and an infected nonunion.Cite this article: Bone Joint J 2022;104-B(9):1095-1100.

Outcome Analysis of the Use of Cerament® in Patients with Chronic Osteomyelitis and Corticomedullary Defects

Background: Chronic osteomyelitis (OM) is a progressive but mostly low-grade infection of the bones. The management of this disease is highly challenging for physicians. Despite systematic treatment approaches, recurrence rates are high. Further, functional and patient-reported outcome data are lacking, especially after osseous defects are filled with bioresorbable antibiotic carriers. Objective: To assess functional and patient-reported outcome measures (PROM) following the administration of Cerament^® G or V due to corticomedullary defects in chronic OM. Methods: We conducted a retrospective study from 2015 to 2020, including all patients who received Cerament^® for the aforementioned reason. Patients were diagnosed and treated in accordance with globally valid recommendations, and corticomedullary defects were filled with Cerament^® G or V, depending on the expected germ spectrum. Patients were systematically followed up, and outcome measures were collected during outpatient clinic visits. Results: Twenty patients with Cierny and Mader type III OM were included in this study and followed up for 20.2 ± 17.2 months (95%CI 12.1–28.3). Ten of these patients needed at least one revision (2.0 ± 1.3 revisions per patient (95%CI 1.1–2.9) during the study period due to OM persistence or local wound complications. There were no statistically significant differences in functional scores or PROMs between groups. Conclusion: The use of Cerament^® G and V in chronic OM patients with corticomedullary defects appears to have good functional outcomes and satisfactory PROMs. However, the observed rate of local wound complications and the OM persistence rate may be higher when compared to previously published data.

Role of Implantable Drug Delivery Devices with Dual Platform Capabilities in the Prevention and Treatment of Bacterial Osteomyelitis

As medicine advances and physicians are able to provide patients with innovative solutions, including placement of temporary or permanent medical devices that drastically improve quality of life of the patient, there is the persistent, recurring problem of chronic bacterial infection, including osteomyelitis. Osteomyelitis can manifest as a result of traumatic or contaminated wounds or implant-associated infections. This bacterial infection can persist as a result of inadequate treatment regimens or the presence of biofilm on implanted medical devices. One strategy to mitigate these concerns is the use of implantable medical devices that simultaneously act as local drug delivery devices (DDDs). This classification of device has the potential to prevent or aid in clearing chronic bacterial infection by delivering effective doses of antibiotics to the area of interest and can be engineered to simultaneously aid in tissue regeneration. This review will provide a background on bacterial infection and current therapies as well as current and prospective implantable DDDs, with a particular emphasis on local DDDs to combat bacterial osteomyelitis.

Ceramic composite with gentamicin decreases persistent infection and increases bone formation in a rat model of debrided osteomyelitis

Introduction: Current methods of managing osteomyelitic voids after debridement are inadequate and result in significant morbidity to patients. Synthetic ceramic void fillers are appropriate for non-infected bone defects but serve as a nidus of re-infection in osteomyelitis after debridement. CERAMENT G (CG) is an injectable ceramic bone void filler which contains gentamicin and is currently being evaluated for use in osteomyelitic environments after debridement due to its theoretical ability to serve as a scaffold for healing while eliminating residual bacteria after debridement through the elution of antibiotics. The goal of this study was to evaluate (1) the rate of persistent infection and (2) new bone growth of a debrided osteomyelitic defect in a rat model which has been treated with either gentamicin-impregnated ceramic cement (CERAMENT G) or the same void filler without antibiotics (CERAMENT, CBVF). Methods: Osteomyelitis was generated in the proximal tibia of Sprague Dawley rats, subsequently debrided, and the defect filled with either (1) CG ( n = 20 ), (2) CBVF ( n = 20 ), or (3) nothing ( n = 20 ). Each group was euthanized after 6 weeks. Infection was detected through bacterial culture and histology. Bone growth was quantified using microCT. Results: Infection was not detected in defects treated with CG as compared with 35 % of defects ( 7 / 20 ) treated with CBVF and 50 % ( 10 / 20 ) of empty defects ( p = 0.001 ). Bone volume in the defect of CG-treated rats was greater than the CBVF (0.21 vs. 0.17, p = 0.021 ) and empty groups (0.21 vs. 0.11, p < 0.001 ) at 6 weeks after implantation. Conclusions: Ceramic void filler with gentamicin (CERAMENT G) decreased the rate of persistent infection and increased new bone growth as compared to the same void filler without antibiotics (CERAMENT) and an empty defect in a rat model of debrided osteomyelitis.

Local Antibiotic Delivery Systems in the Surgical Treatment of Diabetic Foot Osteomyelitis: Again, No Benefit?

This retrospective study aimed to compare the outcomes and healing parameters of 3 groups of surgical treatment combined with and without local antibiotic administration in diabetic foot osteomyelitis (DFO). Overall, 25 patients with DFO who met the criteria were included in the study. Surgical debridement was used with systemic antibiotic administration alone (group A; n = 8) or combined with local application of antibiotic-loaded polymethylmethacrylate beads (group B; n = 9) or antibiotic-loaded hydroxyapatite and calcium sulfate beads (group C; n = 8). In total, 87.5% patients in group A, 100% in group B, and 87.5% in group C healed (P = .543). Median time to healing was 17 weeks in group A, 18 weeks in group B, and 19 weeks in group C (P = .094). One patient (12.5%) in group A was amputated. DFO recurrence rate was 12.5% in group A and 12.5% in group C (P = .543). Median hospitalization was 9 days in group A, 8 days in group B, and 9 days in group C (P = .081). In conclusion, adjunctive local antibiotic therapy was not shown to improve outcomes in surgically treated DFO.

Novel Antimicrobial Peptides Formulated in Chitosan Matrices are Effective Against Biofilms of Multidrug-Resistant Wound Pathogens

INTRODUCTION

Infection frequently complicates the treatment of combat-related wounds, impairs healing, and leads to worse outcomes. To better manage wound infections, antimicrobial therapies that are effective against biofilm and designed for direct wound application are needed. The primary objective of this work was to evaluate a chitosan matrix for delivery of two engineered antimicrobial peptides, (ASP)-1 and ASP-2, to treat biofilm-associated bacteria. A secondary objective was to determine whether replacing the levorotatory (L) form amino acids in ASP-2 with dextrorotatory (D) form amino acids would impact peptide activity.

MATERIALS AND METHODS

Chitosan gels loaded with antimicrobial peptides were evaluated for peptide release over 7 days and tested for efficacy against biofilms grown both in vitro on polymer mesh and ex vivo on porcine skin.

RESULTS

When delivered via chitosan, 70% to 80% of peptides were released over 7 days. Gels eradicated biofilms of gram-positive and gram-negative, drug-resistant bacteria in vitro and ex vivo. Under the conditions tested, no meaningful differences in peptide activity between the L and D forms of ASP-2 were detected.

CONCLUSIONS

Chitosan serves as an effective delivery platform for ASP-1 and ASP-2 to treat biofilm-embedded bacteria and warrants further development as a topical treatment.

Does the induced membrane have antibacterial properties? An experimental rat model of a chronic infected nonunion

INTRODUCTION

The Masquelet procedure proved its efficiency in treating infected nonunion filling bony gaps up to 25 cm. Yet the use of local antibiotics is still questionable in the daily practice with lack of evidence regarding its usefulness in controlling infection. An experimental rat model is put in place to study the antibacterial properties of the induced membrane produced during the first stage of Masquelet.

METHOD

Twenty-three-month-old wistar male rats are inoculated with a 0.5 mL solution of 10^8 CFU/mL MRSA over a critical fracture done on the right femur. Six weeks later, remaining 11 rats exhibiting signs of a chronic infection with a sinus tract and oozing pus along with radiological nonunion are used for a first stage Masquelet procedure. They are randomly divided into two groups with six rats having no local antibiotic in the cement mixture and five rats having 3 g of vancomycin mixed with gentamycin loaded cement. Six weeks later (twelve weeks from baseline), all eleven rats are euthanized and blood samples for C-reactive protein are withdrawn. The induced membrane is identified and resected along with bone fragments and sent for cultures and pathology.

RESULTS

MRSA is isolated in the cultures of all six rats in the first group where no local antibiotic was added. Altered polymorphonuclears with abscess and pus are noted on four of six pathology samples. However in the second group where local antibiotics were added, three out of five rats exhibited eradication of MRSA (p = 0.034) and all samples did not exhibit clear infection signs on pathology. A pyo-epithelioid over a foreign body reaction is seen predominantly in this group demonstrating a regenerative process.

DISCUSSION

The induced membrane does not have antimicrobial properties capable of overcoming an infected nonunion on its own. When local antibiotics were added during the first stage of the Masquelet procedure, new bone formation occurred indicating the need to control an infection in order for bone union to occur.

CONCLUSION

Local antibiotics use in adjunction to extensive debridement is advisable during the first stage of a Masquelet procedure for an infected nonunion.

Infected bone resection plus adjuvant antibiotic-impregnated calcium sulfate versus infected bone resection alone in the treatment of diabetic forefoot osteomyelitis

Background

Managing with diabetic foot osteomyelitis (DFO) is challenging. Even after infective bone resection and thorough debridement, DFO is still difficult to cure and has a high recurrence rate. This retrospective study aims to compare the outcomes of two treatment methods, infected bone resection combined with adjuvant antibiotic-impregnated calcium sulfate and infected bone resection alone, for the treatment of diabetic foot osteomyelitis.

Methods

Between 2015 to 2017, 48 limbs (46 patients) with DFO met the criteria were included for assessment. 20 limbs (18 patients) were included in the calcium sulfate group (the CS group) in which vancomycin and/or gentamicin-impregnated calcium sulfate was used as an adjuvant after infected bone resection while 28 limbs (28 patients) as the control group were undergone infected bone resection only. Systemic antibiotics, postoperative wound care and offloading were continued to be applied following surgery in both groups. The time to healing, healing rate, recurrence rate and amputation rate were compared between the two groups.

Results

In total, 90% (18/20) limbs in the CS group as compared to 78.6% (22/28) infected limbs in the control group went to heal (P = 0.513). The Mean time to healing was 13.3 weeks in the CS group and 11.2 weeks in control group (P = 0.132). Osteomyelitis recurrence rate was 0% (0/18) in the CS group and 36.4% (8/22) in the control group (P = 0.014). Postoperative leakage in calcium sulfate group was 30.0% (6/20) with a mean duration of 8.5 weeks. Amputation rate in the control group was 7.1% (2/28) compared to 0% (0/20) in the CS group (P = 0.153).

Conclusions

Antibiotic-impregnated calcium sulfate as an adjuvant prevents the recurrence of DFO but cannot improve the healing rate, reduce the postoperative amputation rate or shorten the time to healing. Prolonged postoperative leakage as the most common complication can be managed with regular dressing.

Level of Evidence

III, Retrospective Comparative Study.

Clinical experience of debridement combined with resorbable bone graft substitute mixed with antibiotic in the treatment for infants with osteomyelitis

BACKGROUND

Osteomyelitis (OM) is an uncommon disease that originates from many different mechanisms in children. Treatment often involves a combination of surgical debridement combined and antibiotic therapy. The purpose of this article is to evaluate the effect of debridement combined with a new resorbable bone graft substitute (RBGS) mixed with antibiotics in the treatment of infants with OM.

METHODS

Twenty-two patients diagnosed with OM at our institution underwent debridement combined with implantation of RBGS mixed with vancomycin within 48 h after admission. Clinical and epidemiological factors, preoperative and postoperative radiographs, and laboratory parameters, including white blood cell (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and neutrophil percentage (NEU%), were documented. The function of the involved extremity was evaluated at the final follow-up.

RESULTS

The mean age was 6.3 ± 4.8 months (range, 0.5 to 12 months). The mean duration of the symptoms was 14.5 ± 8.4 days (range, 2 to 30 days). The average length of hospitalization was 13.7 ± 6.2 days (range, 6 to 28 days). 13.64% (3/22) had positive results of purulent material obtained at the time of open biopsy and 18.18% (4/22) had positive blood cultures. The most common sites were located in the proximal femur (12), the distal femur (3), and the proximal humerus (3). Ten patients presented with concurrent pyogenic arthritis, while another 12 infants suffered from simple isolated hematogenous OM. The mean follow-up time was 3.0 ± 1.6 years (range, 1.0 to 6.0 years). Seven of 22 patients (31.82%) had complications such as limb length deformity (LLD), avascular necrosis (AVN), and pathologic subluxation of the hip. Fifteen out of 22 (68.18%) patients achieved good results. Additionally, patients who had concomitant pyogenic arthritis were more likely to develop complications than those with isolated OM (p = 0.02).

CONCLUSIONS

Early debridement combined with implantation of RBGS mixed with vancomycin in the treatment of infants with OM achieved acceptable results in this series. Compared to those with simple isolated OM, patients with secondary pyogenic arthritis had a more virulent course.

Single-stage treatment of chronic osteomyelitis with a new absorbable, gentamicin-loaded, calcium sulphate/hydroxyapatite biocomposite: a prospective series of 100 cases

AIMS

Chronic osteomyelitis may recur if dead space management, after excision of infected bone, is inadequate. This study describes the results of a strategy for the management of deep bone infection and evaluates a new antibiotic-loaded biocomposite in the eradication of infection from bone defects.

PATIENTS AND METHODS

We report a prospective study of 100 patients with chronic osteomyelitis, in 105 bones. Osteomyelitis followed injury or surgery in 81 patients. Nine had concomitant septic arthritis. 80 patients had comorbidities (Cierny-Mader (C-M) Class B hosts). Ten had infected nonunions. All patients were treated by a multidisciplinary team with a single-stage protocol including debridement, multiple sampling, culture-specific systemic antibiotics, stabilisation, dead space filling with the biocomposite and primary skin closure.

RESULTS

Patients were followed up for a mean of 19.5 months (12 to 34). Infection was eradicated in 96 patients with a single procedure and all four recurrences were successfully managed with repeat surgery. Adverse events were uncommon, with three fractures, six wound leaks and three unrelated deaths. Outcome was not dependant on C-M host class, microbial culture, wound leakage or presence of nonunion.

CONCLUSION

This single-stage protocol, facilitated by the absorbable local antibiotic, is effective in the treatment of chronic osteomyelitis. It offers a more patient-friendly treatment compared with other published treatment options. Cite this article: Bone Joint J 2016;98-B:1289-96.

Time-Dependent Effectiveness of Locally Applied Vancomycin Powder in a Contaminated Traumatic Orthopaedic Wound Model

OBJECTIVES

To evaluate the effectiveness of locally applied vancomycin powder at different times postinfection in a contaminated traumatic animal model.

METHODS

This study used an established segmental defect rat femur model contaminated with Staphylococcus aureus UAMS-1 followed by treatment at 6 or 24 hours postinfection. Three treatments were evaluated: debridement and irrigation alone (control group) or in combination with either vancomycin powder or vancomycin-impregnated poly(methyl methacrylate) beads. Serum vancomycin levels were determined at scheduled time points over 14 days; bone, surrounding muscle, and implants were harvested for bacterial and inflammatory analyses.

RESULTS

Locally applied vancomycin powder and impregnated beads significantly reduced bacteria both within the bone and implant when treatment was performed at 6 hours. Delaying treatment to 24 hours significantly reduced the therapeutic efficacy of locally applied vancomycin of both groups. Serum vancomycin levels were detectable in all animals treated with vancomycin powder at 24 hours, but absorption was negligible from beads. At 14 days, vancomycin was detectable in the surrounding musculature of all animals and in serum of 20% of animals treated with vancomycin powder.

CONCLUSIONS

This study suggests that vancomycin powder is a promising adjunctive therapy for preventing infection in traumatic wounds when treatment is performed early. This time-dependent effectiveness of vancomycin powder is similar to that observed with systemic and other local delivery adjuncts, which is likely attributable to biofilm formation after contamination, conferring intrinsic recalcitrance to antimicrobials.

Establishing a role for vancomycin powder application for prosthetic joint infection prevention-results of a wear simulation study

Topical vancomycin powder (VP) has shown efficacy and safety in decreasing post-operative spine infections. VP use in arthroplasty has not been established. Concerns remain for third-body wear with the addition of crystalline substrate at the implant interface. The study's purpose was to compare wear behavior of CoCr on UHMWPE to identical wear couples with VP. A six-station wear simulator was utilized and cyclic articulations were run for 10 million cycles (Mc). UHMWPE wear was measured using photography, stereomicroscopy, and gravimetric measurement. There were no differences in wear mark length (P = 0.43), width (P = 0.49), or gravimetric wear at 10 Mc (P = 0.98). VP and control groups lost 0.32 and 0.33 mg, respectively. VP may have a role in PJI prevention. A well-designed clinical study is needed.

Effects of using intravenous antibiotic only versus local intrawound vancomycin antibiotic powder application in addition to intravenous antibiotics on postoperative infection in spine surgery in 907 patients

STUDY DESIGN

A prospective randomized controlled trial.

OBJECTIVE

To assess the ability of local vancomycin powder in controlling postoperative infection in spine surgery.

SUMMARY OF BACKGROUND DATA

Despite improvements through the use of prophylactic systemic antibiotics, surgical site infections remain a significant problem in spine surgical procedures. Various retrospective and prospective studies have reported the efficacy of local application of vancomycin powder in reducing the infection in animal and human studies. However, there were no randomized control trials that reported on its efficacy.

METHODS

Prospective randomized controls of 907 patients with various spinal pathologies were treated surgically during a period of 18 months. The control group received standard systemic prophylaxis only, whereas the treatment group received vancomycin powder in the surgical wound in addition to systemic prophylaxis. Patient demographics, comorbidities, level of spinal pathology, estimated blood loss, nutritional status, and hemoglobin were recorded. Incidence of infection was the primary outcome evaluated.

RESULTS

There were 8 infections (1.68%) in the control group (6 instrumented and 2 noninstrumented, 6 deep and 2 superficial) with bacteria cultured in 3 (1 Escherichia coli and 2 Staphylococcus aureus). In the treatment group, 7 infections (1.61%) were observed (6 instrumented and 1 noninstrumented surgical procedures, 6 deep and 1 superficial) with bacteria cultured in 3 (1 Staphylococcus aureus and 2 Klebsiella). No adverse effects were observed from the use of vancomycin powder. Statistically no significant difference was seen in infection rate between the treatment group and control group.

CONCLUSION

The local application of vancomycin powder in surgical wounds did not significantly reduce the incidence of infection in patients with surgically treated spinal pathologies. The use of vancomycin powder may not be effective when incidence of infection is low.

Comparative effectiveness and cost-benefit analysis of local application of vancomycin powder in posterior spinal fusion for spine trauma

Object

Surgical site infection (SSI) is a morbid complication with high cost in spine surgery. In this era of health care reforms, adjuvant therapies that not only improve quality but also decrease cost are considered of highest value. The authors introduced local application of vancomycin powder into their practice of posterior spinal fusion for spine trauma and undertook this study to determine the value and cost benefit of using vancomycin powder in surgical sites to prevent postoperative infections.

Methods

A retrospective review of 110 patients with traumatic spine injuries treated with instrumented posterior spine fusions over a 2-year period at a single institution was performed. One group (control group) received standard systemic prophylaxis only, whereas another (treatment group) received 1 g of locally applied vancomycin powder (spread over the surgical wound) in addition to systemic prophylaxis. Data were collected on patient demographic characteristics, clinical variables, surgical variables, and 90-day morbidity. Incidence of infection was the primary outcome evaluated, and billing records were reviewed to determine total infection-related medical cost (cost of reoperation/wound debridement, medications, and diagnostic tests). The payer's cost was estimated to be 70% of the total billing cost.

Results

A total of 110 patients were included in the study. The control (n = 54) and treatment groups (n = 56) were similar at baseline. Use of vancomycin powder led to significant reduction in infection rate (13% infection rate in the control group vs 0% in the treatment group, p = 0.02). There were no adverse effects noted from the use of vancomycin powder. The total mean cost of treating postoperative infection per patient was $33,705. Use of vancomycin powder led to a cost savings of $438,165 per 100 posterior spinal fusions performed for traumatic injuries.

Conclusions

The use of adjuvant vancomycin powder was associated with a significant reduction in the incidence of postoperative infection as well as infection-related medical cost. These findings suggest that use of adjuvant vancomycin powder in high-risk patients undergoing spinal fusion is a cost-saving option for preventing postoperative infections, as it can lead to cost-savings of $438,165 per 100 spinal fusions performed.

Modelling for conflict: the legacy of ballistic research and current extremity in vivo modelling

Extremity ballistic injury is unique and the literature intended to guide its management is commonly misinterpreted. In order to care for those injured in conflict and conduct appropriate research, clinicians must be able to identify key in vivo studies, understand their weaknesses and desist the propagation of miscited and misunderstood ballistic dogma. This review provides the only inclusive critical overview of key studies of relevance to military extremity injury. In addition, the non-ballistic studies of limb injury, stabilisation and contamination that will form the basis from which future small animal extremity studies are constructed are presented. With an awareness of the legacy of military wound models and an insight into available generic models of extremity injury and contamination, research teams are well placed to optimise future military extremity injury management.

Internal fixation in a combat theater hospital

Limited data are available on the use of internal fixation in combat zone hospitals. The authors performed a retrospective review of 713 surgical cases during 2 Operation Enduring Freedom deployments to a Level III theater hospital in 2007 and 2009 to 2010. The epidemiology and short- to intermediate-term outcomes of patients treated with internal fixation devices were studied. The authors found that, with judicious use, internal fixation under a damage control protocol in a combat theater hospital can be performed with acceptable complication rates.

Preliminary investigation of crosslinked chitosan sponges for tailorable drug delivery and infection control

Local versus systemic antibiotic delivery may be an effective strategy for treating musculoskeletal infections, especially when antibiotic-resistant bacteria are present. Lyophilized uncrosslinked, genipin crosslinked, and genipin crosslinked with poly(N-isopropylacrylamide) (PNIPAM) chitosan sponges were analyzed for their in vitro degradation rate, chemical crosslinking, antibiotic uptake, elution, biologic activity, and cytotoxicity. These evaluations were pursued to determine if crosslinking with genipin could be used to create a tailorable point of care loaded sponge for local infection control. Crosslinking the chitosan sponges decreased degradation in phosphate-buffered saline from 4.48 ± 2.28 wt % remaining of the uncrosslinked sponges to 78.82 ± 1.15 and 73.87 ± 1.27 wt % remaining at week 1 for the genipin and PNIPAM/genipin crosslinked sponges, respectively. The PNIPAM/genipin crosslinked sponges exhibited the most sustained release of biologically active antibiotics, with an average antibiotic release 63% higher than uncrosslinked and 37% higher than genipin crosslinked sponges, after 96 h. No significant cytotoxic effects from sponges or eluates were exhibited with NIH 3T3 fibroblasts. These preliminary results indicate that genipin crosslinked chitosan sponges, with or without PNIPAM, have potential as local delivery systems for adjunctive therapy for infection control, especially when longer degradation periods and higher antibiotic elutions are desired.

Evaluation of two sources of calcium sulfate for a local drug delivery system: a pilot study

BACKGROUND

Local drug delivery has substantial potential to prevent infections compared with systemic delivery. Although calcium sulfate (CaSO(4)) has been studied for local drug delivery and two types are commercially available, it is unknown whether they differentially release antibiotics.

QUESTIONS/PURPOSES

We determined the differences between two sources of CaSO(4) and the K(2)SO(4) catalyst's presence on the degradation, daptomycin elution, and activity against Staphylococcus aureus.

METHODS

We formed pellets from synthetic and naturally sourced (from gypsum) CaSO(4) and loaded with 5% daptomycin and 3% or 0% K(2)SO(4). We used in vitro experiments to determine the daptomycin concentration and degradation profiles over 10 days. Turbidity assays were used to evaluate the activity of the daptomycin eluates against S. aureus.

RESULTS

All pellets exhibited a bolus release with the highest daptomycin concentration on Day 1 with the sourced CaSO(4) pellets. The synthetic CaSO(4) pellets with 3% K(2)SO(4) exhibited a slower drug release compared with the synthetic CaSO(4) pellets with 0% K(2)SO(4), which degraded and eluted daptomycin too quickly to inhibit S. aureus. Turbidity assays demonstrated that all CaSO(4) pellets inhibit S. aureus for expected lengths of time.

CONCLUSIONS

Our preliminary in vitro data suggest differences in the degradation, elution, and activity properties between sourced and synthetic CaSO(4) pellets. The addition of K(2)SO(4) appeared beneficial when using synthetic CaSO(4). Synthetic CaSO(4) may be effective when slow degradation and longer elution times are needed.

CLINICAL RELEVANCE

Local delivery of eluted daptomycin can be tailored through material selection and K(2)SO(4) addition.

Reduced surgical site infections in patients undergoing posterior spinal stabilization of traumatic injuries using vancomycin powder

BACKGROUND CONTEXT

Despite improvements through the use of prophylactic systemic antibiotics, surgical site infections remain a significant problem in the treatment of traumatic spine injuries. Infection rates as high as 10% have been reported in this population. The impact on patients and cost of treating such infections is profound. Local delivery of antibiotics has been found to be efficacious in animal and human studies as an adjunct to systemic antibiotics in surgical site infection prophylaxis.

PURPOSE

To evaluate the efficacy of using vancomycin powder in surgical sites to prevent infections.

STUDY DESIGN

Retrospective case review.

PATIENT SAMPLE

Patients who underwent posterior spine fusions for traumatic injuries over a 2-year period at a single academic center.

OUTCOME MEASURES

Clinical outcome determined was the incidence of either superficial or deep postoperative wound infections.

METHODS

A retrospective review of 110 patients with traumatic spine injuries treated with instrumented posterior spine fusions over a 2-year period at a single academic center was performed. One group (control group) received standard systemic prophylaxis only, whereas another (treatment group) received vancomycin powder in the surgical wound in addition to systemic prophylaxis. Patient demographics and perioperative information obtained included history of previous spine surgeries, substance use, diabetes, body mass index, level of injury, presence of neurologic deficit, operative time, and estimated blood loss. Incidence of infection was the primary outcome evaluated.

RESULTS

The control (N=54) and treatment groups (N=56) were statistically similar. A statistically significant difference in infection rate was found between the treatment group (0%) and control group (13%, p=.02) without any adverse events. No adverse effects were noted from use of the vancomycin powder.

CONCLUSIONS

The use of vancomycin powder in surgical wounds may significantly reduce the incidence of infection in patients with traumatic spine injuries treated with instrumented posterior spine fusion. Applying vancomycin powder to surgical wounds is a promising means of preventing costly and harmful postoperative wound infections in high-risk populations.

Infection in conflict wounded

Although mechanisms of modern military wounding may be distinct from those of ancient conflicts, the infectious sequelae of ballistic trauma and the evolving microbial flora of war wounds remain a considerable burden on both the injured combatant and their deployed medical systems. Battlefield surgeons of ancient times favoured suppuration in war wounding and as such Galenic encouragement of pus formation would hinder progress in wound care for centuries. Napoleonic surgeons eventually abandoned this mantra, embracing radical surgical intervention, primarily by amputation, to prevent infection. Later, microscopy enabled identification of microorganisms and characterization of wound flora. Concurrent advances in sanitation and evacuation enabled improved outcomes and establishment of modern military medical systems. Advances in medical doctrine and technology afford those injured in current conflicts with increasing survivability through rapid evacuation, sophisticated resuscitation and timely surgical intervention. Infectious complications in those that do survive, however, are a major concern. Addressing antibiotic use, nosocomial transmission and infectious sequelae are a current clinical management and research priority and will remain so in an era characterized by a massive burden of combat extremity injury. This paper provides a review of infection in combat wounding from a historical setting through to the modern evidence base.

Diagnosis and management of chronic infection

High-energy penetrating extremity injuries are often associated with severe open fractures that have varying degrees of soft-tissue contamination and tenuous soft-tissue coverage. The result is a relatively high prevalence of chronic osteomyelitis compared with that in civilian trauma patients. Diagnosing chronic osteomyelitis requires a careful history and thorough physical and radiographic examinations. Cross-sectional imaging can help delineate the extent of bony involvement, and scintigraphy can be used as a diagnostic tool and to gauge response to treatment. Clinical staging also directs surgical management. Adequacy of débridement remains the most important clinical predictor of success; thus, adopting an oncologic approach to complete (ie, wide) excision is important. Reconstruction can be safely performed by a variety of methods; however, proper staging and patient selection remain critical to a successful outcome. Although systemic and depot delivery of antibiotics plays a supporting role in the treatment of chronic osteomyelitis, the ideal dosing regimens, and the duration of treatment, remain controversial.

Local antibiotic delivery using tailorable chitosan sponges: the future of infection control?

OBJECTIVES

Local antibiotic delivery is a viable and attractive option for preventing infection. Unfortunately, the current options are limited and often necessitate surgical removal. This study evaluates the ability of a biodegradable and biocompatible chitosan sponge to minimize infection by delivering local antibiotics within the wound.

METHODS

A complex musculoskeletal wound was created on the hindlimb of goats and contaminated with Pseudomonas aeruginosa (lux) or Staphylococcus aureus (lux) bacteria. These bacteria are genetically engineered to emit photons, allowing for quantification with a photon-counting camera system. The wounds were closed and similarly débrided and irrigated with 9 L normal saline using bulb-syringe irrigation 6 hours after inoculation. Goats were assigned to different treatment groups: a control group with no adjunctive treatment and an experimental group using a chitosan sponge loaded with either amikacin (for wounds contaminated with P. aeruginosa) or vancomycin (for wounds contaminated with S. aureus). The wounds were closed after the procedure and evaluated 48 hours after initial contamination. Serum levels of the antibiotics were also measured at 6, 12, 24, 36, and 42 hours after treatment was initiated.

RESULTS

The wounds treated with the antibiotic-loaded chitosan sponge had significantly less bacteria than the untreated wounds (P < 0.05). The highest serum levels were 6 hours after treatment but remained less than 15% of target serum levels for systemic treatment. At study end point, all sponges were between 60% and 100% degraded.

CONCLUSIONS

The chitosan sponges are effective delivering the antibiotic and reducing the bacteria within the wounds.

Determination of antibacterial properties and cytocompatibility of silver-loaded coral hydroxyapatite

In this study, silver-loaded coral hydroxyapatites (SLCHAs) were used as scaffolds for bone tissue engineering. The SLCHAs were prepared by surface adsorption process and ion-exchange reaction between Ca(2+) of coral hydroxyapatite (CHA) and Ag(+) of silver nitrate with different concentrations at room temperature. The properties of the composite SLCHAs were investigated by inductively coupled plasma-atomic emission spectrometry (ICP-AES), scanning electron microscropy (SEM) equipped with backscattered electron detector (BSE), and energy-dispersive X-ray spectrometer (EDS). The SEM images showed that the morphology of the SLCHAs depended on the content of Ag(+), and the silver ions were uniformly distributed on the surface of SLCHAs. The ICP-AES results demonstrated that the silver content of the SLCHAs decreased along with the decrease of the concentration of silver nitrate. The SLCHAs were found effective against Escherichia coli and Staphylococcus aureus by antibacterial test. Mouse embryonic pre-osteoblast cells (MC3T3-E1) were used to test the cytocompatibility of SLCHAs, CHA, and pure coral. Cell morphology and cell proliferation were studied with SEM, laser scanning confocal microscope (LSCM), and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay after 1, 3, and 5 days of culture. The results indicated the cell morphology and proliferation on the scaffolds of Ag(+) (13.6 microg/ml)/CHA and Ag(+) (1.7 microg/ml)/CHA were better than that on Ag(+) (170 microg/ml)/CHA. In addition, adhesion of MC3T3-E1 on the scaffolds showed that the confluent cells showed fusiform shape and arranged tightly on the scaffolds. All the results showed that the antibacterial SLCHAs would have potential clinical application as the scaffolds for bone tissue engineering.