Local Delivery of Vancomycin for the Prophylaxis of Prosthetic Device-Related Infections

In vitro and in vivo assessment of extended duration cathodic voltage-controlled electrical stimulation for treatment of orthopedic implant-associated infections

Effective treatment of orthopedic implant-associated infections (IAIs) remains a clinical challenge. The in vitro and in vivo studies presented herein evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) to titanium implants inoculated with preformed bacterial biofilms of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that combining vancomycin therapy (500 µg/mL) with application of CVCES at -1.75 V (all voltages are with respect to Ag/AgCl unless otherwise stated) for 24 h resulted in 99.98% reduction in the coupon-associated MRSA colony-forming units (CFUs) (3.38 × 103 vs. 2.14 × 107 CFU/mL, p < 0.001) and a 99.97% reduction in the planktonic CFU (4.04 × 104 vs. 1.26 × 108 CFU/mL, p < 0.001) as compared with the no treatment control samples. The in vivo studies utilized a rodent model of MRSA IAIs and showed a combination of vancomycin therapy (150 mg/kg twice daily) with CVCES of -1.75 V for 24 h had significant reductions in the implant associated CFU (1.42 × 101 vs. 1.2 × 106 CFU/mL, p < 0.003) and bone CFU (5.29 × 101 vs. 4.48 × 106 CFU/mL, p < 0.003) as compared with the untreated control animals. Importantly, the combined 24 h CVCES and antibiotic treatments resulted in no implant-associated MRSA CFU enumerated in 83% of the animals (five out of six animals) and no bone-associated MRSA CFU enumerated in 50% of the animals (three out of six animals). Overall, the outcomes of this study have shown that extended duration CVCES therapy is an effective adjunctive therapy to eradicate IAIs.

Intraoperative Topical Antibiotics for Infection Prophylaxis in Pelvic and Acetabular Surgery

OBJECTIVES

To determine if topical vancomycin and tobramycin powder reduces the incidence of surgical site infection after pelvic ring and acetabulum fracture surgery.

DESIGN

Retrospective cohort study.

SETTING

University of Alabama at Birmingham, Academic Level I Trauma Center.

PATIENTS/PARTICIPANTS

Two hundred nineteen patients (140 meeting inclusion criteria) with pelvic and acetabular fractures who underwent open reduction and internal fixation from March 2012 to November 2013.

INTERVENTION

One gram vancomycin and 1.2 g tobramycin powder applied deep in the surgical wound of the treatment group.

MAIN OUTCOME MEASUREMENTS

Postoperative infection rate.

RESULTS

One hundred forty patients were included. Control group (n = 69) and treatment group (n = 71) were similar for sex, age, ethnicity, and body mass index. There was no difference between groups with regards to renal function postoperative day 2 (P = 0.24). The risk of infection was 14.5% and 4.2% (P = 0.04) for the control and treatment groups, respectively. No significant effect of antibiotic treatment was observed overall after adjusting for EBL (odds ratio 0.20, 95% confidence interval, 0.02-1.06). Of note, a nonsignificant 71% increase was observed among those with ≥1 L EBL (odds ratio 1.71, 95% confidence interval, 0.02-147.02).

CONCLUSIONS

Topical antibiotics possibly reduce the incidence of surgical site infection after open pelvic and acetabulum fixation without increasing risk of renal impairment. The protective effect of topical antibiotics may be limited to patients with minimal intraoperative blood loss.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Infection prevention using affinity polymer-coated, synthetic meshes in a pig hernia model

BACKGROUND

Given concern for hernia mesh infection, surgeons often use biologic mesh which may provide reduced risk of infection but at the cost of decreased repair durability. We evaluated mesh coating to provide sustained release of antibiotics to prevent prosthetic mesh infection and also allow a durable repair.

MATERIALS AND METHODS

Cyclodextrin-based polymer was crosslinked onto multifilament polyester mesh and loaded with vancomycin (1.75 mg/cm²). Pigs received modified meshes (n = 6) or normal, untreated meshes (n = 4), which were implanted into acute 10 × 5 cm ventral hernia, then directly inoculated with 10⁶ colony-forming unit (CFU) of methicillin-resistant Staphylococcus aureus (MRSA). These were compared to animals receiving normal, uninfected mesh. All mesh was secured in an underlay bridge manner, and after 30 d, the abdominal wall was removed for quantitative bacterial culture and biomechanical analysis.

RESULTS

All animals survived 30 d. All six animals with coated mesh cleared MRSA infection. The four control animals did not clear MRSA (P = 0.005). Quantitative bacterial load was higher in standard mesh versus drug-delivery mesh group (2.34 × 10⁴versus 80.9 CFU/gm). These data were log₁₀-transformed and analyzed by Welch's t-test (P = 0.001). Minimum number of CFUs detectable by assay (300) was used instead of zero. Biomechanical analysis of controls (1.82 N/mm infected; 1.71 N/mm uninfected) showed no difference to the modified meshes (1.31 N/mm) in tissue integration (P = 0.15).

CONCLUSIONS

We successfully prevented synthetic mesh infection in a pig model using a cyclodextrin-based polymer to locally deliver vancomycin to the hernia repair site and clearing antibiotic-resistant bacteria. Polymer coating did not impact the strength of the hernia repair.

Cathodic Voltage-controlled Electrical Stimulation Plus Prolonged Vancomycin Reduce Bacterial Burden of a Titanium Implant-associated Infection in a Rodent Model

BACKGROUND

Cathodic voltage-controlled electrical stimulation (CVCES) of titanium implants, either alone or combined with a short course of vancomycin, has previously been shown to reduce the bone and implant bacterial burden in a rodent model of methicillin-resistant Staphylococcus aureus (MRSA) implant-associated infection (IAI). Clinically, the goal is to achieve complete eradication of the IAI; therefore, the rationale for the present study was to evaluate the antimicrobial effects of combining CVCES with prolonged antibiotic therapy with the goal of decreasing the colony-forming units (CFUs) to undetectable levels.

QUESTIONS/PURPOSES

(1) In an animal MRSA IAI model, does combining CVCES with prolonged vancomycin therapy decrease bacteria burden on the implant and surrounding bone to undetectable levels? (2) When used with prolonged vancomycin therapy, are two CVCES treatments more effective than one? (3) What are the longer term histologic effects (inflammation and granulation tissue) of CVCES on the surrounding tissue?

METHODS

Twenty adult male Long-Evans rats with surgically placed shoulder titanium implants were infected with a clinical strain of MRSA (NRS70). One week after infection, the rats were randomly divided into four groups of five: (1) VANCO: only vancomycin treatment (150 mg/kg, subcutaneous, twice daily for 5 weeks); (2) VANCO + 1STIM: vancomycin treatment (same as the VANCO group) coupled with one CVCES treatment (-1.8 V for 1 hour on postoperative day [POD] 7); (3) VANCO + 2STIM: vancomycin treatment (same as the VANCO group) coupled with two CVCES treatments (-1.8 V for 1 hour on POD 7 and POD 21); or (4) CONT: no treatment. On POD 42, the implant, bone, and peripheral blood were collected for CFU enumeration and histological analysis, where we compared CFU/mL on the implants and bone among the groups. A pathologist, blinded to the experimental conditions, performed a semiquantitative analysis of inflammation and granulation tissue present in serial sections of the humeral head for animals in each experimental group.

RESULTS

The VANCO + 1STIM decreased the implant bacterial burden (median = 0, range = 0-10 CFU/mL) when compared with CONT (median = 5.7 × 10(4), range = 4.0 × 10(3)-8.0 × 10(5) CFU/mL; difference of medians = -5.6 × 10(4); p < 0.001) and VANCO (median = 4.9 × 10(3), range = 9.0 × 10(2)-2.1 × 10(4) CFU/mL; difference of medians = -4.9 × 10(3); p < 0.001). The VANCO + 1STIM decreased the bone bacterial burden (median = 0, range = 0-0 CFU/mL) when compared with CONT (median = 1.3 × 10(2), range = 0-9.4 × 10(2) CFU/mL; difference of medians = -1.3 × 10(2); p < 0.001) but was not different from VANCO (median = 0, range = 0-1.3 × 10(2) CFU/mL; difference of medians = 0; p = 0.210). The VANCO + 2STIM group had implant CFU (median = 0, range = 0-8.0 × 10(1) CFU/mL) and bone CFU (median = 0, range = 0-2.0 × 10(1) CFU/mL) that were not different from the VANCO + 1STIM treatment group implant CFU (median = 0, range = 0-10 CFU/mL; difference of medians = 0; p = 0.334) and bone CFU (median = 0, range = 0-0 CFU/mL; difference of medians = 0; p = 0.473). The histological analysis showed no deleterious effects on the surrounding tissue as a result of the treatments.

CONCLUSIONS

Using CVCES in combination with prolonged vancomycin resulted in decreased MRSA bacterial burden, and it may be beneficial in treating biofilm-related implant infections.

CLINICAL RELEVANCE

CVCES combined with clinically relevant lengths of vancomycin therapy may be a treatment option for IAI and allow for component retention in certain clinical scenarios. However, more animal research and human trials confirming the efficacy of this approach are needed before such a clinical recommendation could be made.

Evaluation of the Antimicrobial Efficacy of a Novel Rifampin/Minocycline-Coated, Noncrosslinked Porcine Acellular Dermal Matrix Compared With Uncoated Scaffolds for Soft Tissue Repair

Background Despite meticulous aseptic technique and systemic antibiotics, bacterial colonization of mesh remains a critical issue in hernia repair. A novel minocycline/rifampin tyrosine-coated, noncrosslinked porcine acellular dermal matrix (XenMatrix AB) was developed to protect the device from microbial colonization for up to 7 days. The objective of this study was to evaluate the in vitro and in vivo antimicrobial efficacy of this device against clinically isolated methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Methods XenMatrix AB was compared with 5 existing uncoated soft tissue repair devices using in vitro methods of zone of inhibition (ZOI) and scanning electron microscopy (SEM) at 24 hours following inoculation with MRSA or E coli These devices were also evaluated at 7 days following dorsal implantation and inoculation with MRSA or E coli (60 male New Zealand white rabbits, n = 10 per group) for viable colony-forming units (CFU), abscess formation and histopathologic response, respectively. Results In vitro studies demonstrated a median ZOI of 36 mm for MRSA and 16 mm for E coli for XenMatrix AB, while all uncoated devices showed no inhibition of bacterial growth (0 mm). SEM also demonstrated no visual evidence of MRSA or E coli colonization on the surface of XenMatrix AB compared with colonization of all other uncoated devices. In vivo XenMatrix AB demonstrated complete inhibition of bacterial colonization, no abscess formation, and a reduced inflammatory response compared with uncoated devices. Conclusion We demonstrated that XenMatrix AB possesses potent in vitro and in vivo antimicrobial efficacy against clinically isolated MRSA and E coli compared with uncoated devices.

Cathodic Electrical Stimulation Combined With Vancomycin Enhances Treatment of Methicillin-resistant Staphylococcus aureus Implant-associated Infections

BACKGROUND

Effective treatments for implant-associated infections are often lacking. Cathodic voltage-controlled electrical stimulation has shown potential as a treatment of implant-associated infections of methicillin-resistant Staphylococcus aureus (MRSA).

QUESTIONS/PURPOSES

The primary purpose of this study was to (1) determine if cathodic voltage-controlled electrical stimulation combined with vancomycin therapy is more effective at reducing the MRSA bacterial burden on the implant, bone, and synovial fluid in comparison to either treatment alone or no treatment controls. We also sought to (2) evaluate the histologic effects of the various treatments on the surrounding bone; and to (3) determine if the cathodic voltage-controlled electrical stimulation treatment had an effect on the mechanical properties of the titanium implant as a result of possible hydrogen embrittlement.

METHODS

Thirty-two adult male Long-Evans rats (Harlan Laboratories, Indianapolis, IN, USA) with surgically placed shoulder titanium implants were infected with a clinical strain of MRSA (NRS70). One week after infection, eight animals received a treatment of cathodic voltage-controlled electrical stimulation at -1.8 V versus Ag/AgCl for 1 hour (STIM), eight received vancomycin twice daily for 1 week (VANCO), eight received the cathodic voltage-controlled electrical stimulation and vancomycin therapy combined (STIM + VANCO), and eight served as controls with no treatment (CONT). Two weeks after initial infection, the implant, bone, and synovial fluid were collected for colony-forming unit (CFU) enumeration, qualitative histological analysis by a pathologist blinded to the treatments each animal received, and implant three-point bend testing.

RESULTS

The implant-associated CFU enumerated from the STIM + VANCO (mean, 3.7 × 10(3); SD, 6.3 × 10(3)) group were less than those from the CONT (mean, 1.3 × 10(6); SD, 2.8 × 10(6); 95% confidence interval [CI] of difference, -4.3 × 10(5) to -9.9 × 10(3); p < 0.001), STIM (mean, 1.4 × 10(6); SD, 2.0 × 10(6); 95% CI of difference, -2.1 × 10(6) to -1.8 × 10(3); p = 0.002), and VANCO (mean, 5.8 x 10(4); SD, 5.7 × 10(4); 95% CI of difference, -6.4 × 10(4) to -1.7 × 10(4); p < 0.001) group. The bone-associated CFU enumerated from the STIM + VANCO group (6.3 × 10(1); SD, 1.1 × 10(2)) were less than those from the CONT (mean, 2.8 × 10(5); SD, 4.8 × 10(5); 95% CI of difference, -9.4 × 10(4) to -5.0 × 10(3); p < 0.001) and STIM (mean, 2.6 × 10(4); SD, 2.5 × 10(4); 95% CI of difference, -4.1 × 10(4) to -1.6 × 10(3); p < 0.001) groups. The VANCO group (4.3 × 10(5); SD, 6.3 × 10(2)) also had lower bone-associated CFU as compared with the CONT (mean 95% CI of difference, -9.3 × 10(4) to -4.5 × 10(3); p < 0.001) and STIM (95% CI of difference, -4.0 × 10(4) to -1.5 × 10(3); p < 0.001) groups. In comparison to the synovial fluid CFU enumerated from the CONT group (mean, 3.3 × 10(4); SD, 6.0 × 10(4)), lower synovial CFU were reported for both the STIM + VANCO group (mean, 4.6 × 10(1); SD, 1.2 × 10(2); 95% CI of difference, -4.9 × 10(3) to -3.0 × 10(2); p < 0.001) and the VANCO group (mean, 6.8 × 10(1); SD, 9.2 × 10(1); 95% CI of difference, -4.9 × 10(3) to -2.8 × 10(2); p = 0.007). The histological analysis showed no discernable deleterious effects on the surrounding tissue as a result of the treatments. No brittle fracture occurred during mechanical testing and with the numbers available, no differences in implant flexural yield strength were detected between the groups.

CONCLUSIONS

In this rodent model, cathodic voltage-controlled electrical stimulation combined with vancomycin is an effective treatment for titanium implant-associated infections showing greater than 99.8% reduction in bacterial burden on the implant, surrounding bone, and synovial fluid as compared with the controls and the stimulation alone groups.

CLINICAL RELEVANCE

Cathodic voltage-controlled electrical stimulation combined with vancomycin may enable successful treatment of titanium orthopaedic implant-associated infections with implant retention. Future studies will focus on optimization of the stimulation parameters for complete eradication of infection and the ability to promote beneficial host tissue responses.

Application of Intrawound Vancomycin Powder during Spine Surgery in a Patient with Dialysis-Dependent Renal Failure

Surgical site infections (SSIs) after spinal surgery are a serious complication that can be minimized with prophylaxis. Vancomycin is a common agent used in the prevention of SSI. Given that vancomycin is renally cleared, its use requires careful observation in dialysis-dependent patients due to toxicity at supratherapeutic levels. Since minimum inhibitory concentrations (MICs) for vancomycin have increased due to the emergence of resistant pathogens, the use of vancomycin in such patients is further complicated. Local instillation of vancomycin powder is thought to provide additional protection against SSI and have lower systemic absorption. We present a patient with end-stage renal disease that developed progressively debilitating cervical spondylotic myelopathy necessitating multilevel laminectomy and instrumented fusion. Prior to closure, 1 gram of vancomycin powder was sprinkled into the surgical incision. Postoperative serum vancomycin levels were well below those associated with nephrotoxicity and ototoxicity. Based on this experience, we reviewed the relevant guidelines that were designed to prevent postoperative infections in such dialysis-dependent patients. Intrawound application of vancomycin may be a legitimate and safe option for SSI prophylaxis in patients with renal failure on dialysis.

Preparation and characterisation of Punica granatum pericarp aqueous extract loaded chitosan-collagen-starch membrane: role in wound healing process

Engineered scaffolds made from natural biomaterials are crucial elements in tissue engineering strategies. In this study, biological scaffold like chitosan-collagen-starch membrane (CCSM) loaded with the antibacterial agent, Punica granatum pericarp aqueous extract was explored for enhanced regeneration of epithelial tissue during wound healing. Collagen was extracted from Rachycentron canadum fish skin. Membranous scaffold was prepared by mixing collagen, starch and chitosan in a fixed proportion, loaded with aqueous extract of P. granatum and its anti-pseudomonal activity was studied. Morphological characterization by SEM and mechanical property like tensile strength of the membrane were studied. Excision wound of 2 cm(2) size was induced in Guinea pig and the effect of P. granatum extract loaded CCSM in wound healing was studied. The SEM image showed deep pores in the membrane and also possessed good tensile strength. Wound surface area was reduced prominently in the experimental group with P. granatum extract loaded CCSM when compared to the group with unloaded membrane and the one with no membrane. Punica granatum extract loaded CCSM has antipseudomonal property and supported enhanced epithelial cell proliferation without leaving a scar after wound healing. This has significant therapeutic application in membranous scaffold mediated skin repair and regeneration.

Vancomycin-eluting niosomes: a new approach to the inhibition of staphylococcal biofilm on abiotic surfaces

A new vancomycin (VCM)-eluting mixed bilayer niosome formulation was evaluated for the control of staphylococcal colonization and biofilm formation on abiotic surfaces, a niosome application not explored to date. Cosurfactant niosomes were prepared using a Span 60/Tween 40/cholesterol blend (1: 1: 2). Tween 40, a polyethoxylated amphiphile, was included to enhance VCM entrapment and confer niosomal surface properties precluding bacterial adhesion. VCM-eluting niosomes showed good quality attributes including relatively high entrapment efficiency (∼50%), association of Tween 40 with vesicles in a constant proportion (∼87%), biphasic release profile suitable for inhibiting early bacterial colonization, and long-term stability at 4°C for a 12-month study period. Niosomes significantly enhanced VCM activity against planktonic bacteria of nine staphylococcal strains. Using microtiter plates as abiotic surface, VCM-eluting niosomes proved superior to VCM in inhibiting biofilm formation, eradicating surface-borne biofilms, inhibiting biofilm growth, and interfering with biofilm induction by VCM subminimal inhibitory concentrations. Data suggest dual functionality of cosurfactant VCM-eluting niosomes as passive colonization inhibiting barrier and active antimicrobial-controlled delivery system, two functions recognized in infection control of abiotic surfaces and medical devices.

Role of size and shape on biofilm eradication for nitric oxide-releasing silica nanoparticles

Nitric oxide (NO), a reactive free radical, has proven effective in eradicating bacterial biofilms with reduced risk of fostering antibacterial resistance. Herein, we evaluated the efficacy of NO-releasing silica nanoparticles against Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus biofilms as a function of particle size and shape. Three sizes of NO-releasing silica nanoparticles (i.e., 14, 50, and 150 nm) with identical total NO release (∼0.3 μmol/mg) were utilized to study antibiofilm eradication as a function of size. To observe the role of particle shape on biofilm killing, we varied the aspect ratio of the NO-releasing silica particles from 1 to 8 while maintaining constant particle volume (∼0.02 μm(3)) and NO-release totals (∼0.7 μmol/mg). Nitric oxide-releasing particles with decreased size and increased aspect ratio were more effective against both P. aeruginosa and S. aureus biofilms, with the Gram-negative species exhibiting the greatest susceptibility to NO. To further understand the influence of these nanoparticle properties on NO-mediated antibacterial activity, we visualized intracellular NO concentrations and cell death with confocal microscopy. Smaller NO-releasing particles (14 nm) exhibited better NO delivery and enhanced bacteria killing compared to the larger (50 and 150 nm) particles. Likewise, the rod-like NO-releasing particles proved more effective than spherical particles in delivering NO and inducing greater antibacterial action throughout the biofilm.

From in vitro to in vivo Models of Bacterial Biofilm-Related Infections

The influence of microorganisms growing as sessile communities in a large number of human infections has been extensively studied and recognized for 30–40 years, therefore warranting intense scientific and medical research. Nonetheless, mimicking the biofilm-life style of bacteria and biofilm-related infections has been an arduous task. Models used to study biofilms range from simple in vitro to complex in vivo models of tissues or device-related infections. These different models have progressively contributed to the current knowledge of biofilm physiology within the host context. While far from a complete understanding of the multiple elements controlling the dynamic interactions between the host and biofilms, we are nowadays witnessing the emergence of promising preventive or curative strategies to fight biofilm-related infections. This review undertakes a comprehensive analysis of the literature from a historic perspective commenting on the contribution of the different models and discussing future venues and new approaches that can be merged with more traditional techniques in order to model biofilm-infections and efficiently fight them.

Colonization of peripheral intravascular catheters with biofilm producing microbes: Evaluation of risk factors

BACKGROUND

Biofilms often colonize catheters and contribute to catheter-related septicemia. However, predictors of catheter colonization by biofilms remain poorly defined. The aim of this study was to evaluate clinical factors that may be associated with biofilm colonization of catheters.

MATERIALS AND METHODS

A total of 54 isolates colonizing the peripheral intravascular catheters (IVCs) were studied and their biofilm production ability was analyzed by the tube method and antimicrobial susceptibility was also done. A detailed clinical history and examination was done of each subject to know age, sex, duration of use of IVCs, site of IVCs, swelling/purulence around the IVCs, number of attempts to install the catheter, and duration of hospital stay.

RESULTS

44 (81.4%) out of 54 isolates colonizing the catheters showed biofilm formation. Biofilm formations were significantly associated with duration of hospital stay of more than 7 days [odds ratio (OR) = 6.6; 95% confidence interval (CI) = 1.3-34; P value (P) = 0.02], multiple attempts to install the catheter (OR=7; CI=1.5-31.8; P=0.01), and multidrug resistance (OR=9.5; CI=1.8 - 51.1: P=0.008). Klebsiella pneumoniae and Candida spp. comprised most of the biofilm-producing isolates. The overall susceptibility to antimicrobials was low among biofilm-producing compared to nonbiofilm-producing microbes.

CONCLUSION

The results of this study suggest that evaluation of predictors of biofilm production is important in order to understand, prevent or manage biofilm colonization of IVCs.

Intrawound application of vancomycin for prophylaxis in instrumented thoracolumbar fusions: efficacy, drug levels, and patient outcomes

STUDY DESIGN

A retrospective cohort study from a single institution of a consecutive series of spine surgery patients.

OBJECTIVE

To evaluate the safety and efficacy of adjunctive local application of vancomycin for infection prophylaxis in posterior instrumented thoracic and lumbar spine wounds compared to IV cephalexin alone.

SUMMARY OF BACKGROUND DATA

Cephalosporin resistant strains of staphylococcus (MRSA and coagulase negative staph) have diminished the efficacy of intravenous antibiotic prophylaxis for instrumented spine fusion. Intravenous vancomycin prophylaxis has not been shown to decrease wound infection rates compared to IV cephalosporins. Adjunctive application of vancomycin powder in wounds for instrumented spinal fusion surgery may decrease infection rates.

METHODS

Since 2000, 1732 consecutive thoracic and lumbar posterior instrumented spinal fusions have been performed with routine 24 hours of perioperative intravenous antibiotic prophylaxis with cephalexin. Since 2006, 911 of these instrumented thoracic and lumbar cases had 2 g of vancomycin powder applied to the wound before closure in addition to intravenous antibiotics. A retrospective review for infection rates and complications was performed. Oswestry and SF-36 outcomes instruments were completed before surgery, immediately after surgery, and at latest follow-up. The average follow-up is 2.5 years, range 1 to 7 years.

RESULTS

Eight hundred twenty-one posterior instrumented thoracic and lumbar fusions were preformed using intravenous cephalexin prophylaxis with a total of 21 deep wound infections (2.6%). Coag negative staph was the most commonly isolated organism. Nine hundred eleven posterior instrumented thoracic and lumbar fusions have been performed with IV cephalexin plus adjunctive local vancomycin powder with two deep wound infections (0.2%). The reduction in wound infections was statistically significant (P < 0.0001). There were no adverse clinical outcomes or wound complications related to the local application of vancomycin.

CONCLUSION

Adjunctive local application of vancomycin powder decreases the postsurgical wound infection rate with statistical significance in posterior instrumented thoracolumbar spine fusions.

Less-invasive and highly effective method for preventing methicillin-resistant Staphylococcus aureus graft infection by local sustained release of vancomycin

OBJECTIVE

Methicillin-resistant Staphylococcus aureus graft infection is one of the most serious complications of vascular surgery. Vancomycin is a potent antibiotic against methicillin-resistant S. aureus; however, systemic administration of vancomycin is not very effective against methicillin-resistant S. aureus graft infection. Therefore, we investigated whether a local sustained release of vancomycin prevents methicillin-resistant S. aureus graft infection.

METHODS

We have developed a poly-L-lactide-co-caprolactone sheet that enabled sustained release of vancomycin for 2 weeks. An expanded polytetrafluoroethylene vascular graft patch (1.5 mm2) was sutured at the anterior wall of the incised murine abdominal aorta. Methicillin-resistant S. aureus (1.0 x 10(3) colony-forming units) was inoculated onto the graft surface. Thereafter, the graft was treated as follows (n = 6 each): no treatment (control group), local injection of an aqueous solution of vancomycin (vancomycin solution group) and local implantation of poly-L-lactide-co-caprolactone containing vancomycin (vancomycin-PLCA group). After 7 days, the graft and blood were sampled and cultured.

RESULTS

The methicillin-resistant S. aureus counts in the grafts of the vancomycin-PLCA group were significantly lower than those of the other groups. Blood cultures of the vancomycin-PLCA group were all negative, whereas those of the other groups were all positive for infection. The survival rate in the vancomycin-PLCA group at 28 days was considerably higher than that in the control group (83.3% vs 16.7%).

CONCLUSIONS

A local sustained-release sheet containing vancomycin reduced methicillin-resistant S. aureus counts in the infected vascular grafts, prevented sepsis, and drastically improved survival rates. This can be used as a highly effective and less-invasive adjunctive treatment method for preventing prosthetic methicillin-resistant S. aureus graft infection.

Bacterial biofilms within the clinical setting: what healthcare professionals should know

Bacterial biofilm formation is the prevailing microbial lifestyle in natural and manmade environments and occurs on all surface types. Biofilm formation develops in several phases and is influenced by various parameters, both environmental and inherent to the attaching cell. Biofilms also serve as protective niches for particular pathogens when outside a host. Although it is accepted that biofilms are ubiquitous in nature, the significance of biofilms in clinical settings, especially with regard to their role in medical-related infections, is often underestimated. It has been found that several aspects of human pathogenesis within a clinical context are directly related to biofilm development. Various types of surfaces in clinical settings are prone to biofilm development and an increased risk of disease may be a direct consequence of their formation. This review describes the process of biofilm formation, highlights the importance of bacterial associations with surfaces in clinical settings and describes various methods for biofilm visualization and control.

Current advances in sustained-release systems for parenteral drug delivery

Major progresses in the development of parenteral sustained-release systems have been made in recent years as evidenced by the regulatory approval and market launch of several new products. Both the availability of novel carrier materials and the advances in method of fabrication have contributed to these commercial successes. With the formulation challenges associated with biologics, new delivery systems have also been evolved specifically to address the unmet needs in the parenteral sustained release of proteins. In this review paper, different new carriers systems and preparation methods are discussed with special focus on their applications to biologicals.