Topical application of povidone‐iodine before wound closure is associated with significant increase in serum iodine level

Aim: To determine serum iodine level before and after local application of povidone‐iodine before wound closure in cardiac surgery patients. Povidone‐iodine is a popular antiseptic solution that has been widely used in perioperative wound management of surgical patients. Despite its widespread usage, little is known concerning the absorption profile and potential systemic toxicity. Methods: We carried out a prospective study on the serum iodine level and corresponding renal function in consecutive patients operated on at our cardiac surgical unit. Results: There was a statistically significant increase in serum iodine level and patients with impaired renal function defined by creatinine level showed significantly higher postoperative iodine levels. Conclusion: Systemic iodine absorption is evidence that, even with single wound irrigation, repeated usage should be avoided in patients with renal impairment.     

Combined local and systemic antibiotic treatment is effective against experimental Staphylococcus aureus peri‐implant biofilm infection

We hypothesized that systemic ceftriaxone and high concentration local antibiotics might eradicate peri‐implant sepsis. Experiment 1: Eighty‐four implants inoculated with biofilm‐forming Staphylococcus aureus were treated in vitro with gentamicin, vancomycin, gentamicin + rifampin, or vancomycin + rifampin for 2, 4, or 8 days. Experiment 2: Forty‐five implants were wired in vivo to rat femurs and inoculated with 1 × 10⁶ CFU S. aureus. After 48 h, rats were treated once daily for 5 days with systemic ceftriaxone, local tobramycin or ceftriaxone, and tobramycin. Experiment 3: Forty implants with established S. aureus biofilms were wired in vivo to rat femurs. After 48 h, rats were treated with systemic ceftriaxone alone or in combination with local gentamicin, gentamicin and rifampin, or vancomycin. Experiment 1: 100% of implants treated in vitro with gentamicin were sterile after 48 h. The other treatments did not become sterile until 4 days. Experiment 2: No implant was culture negative. The combination of systemic ceftriaxone and local tobramycin was significantly better than others (p < 0.008). Experiment 3: Systemic ceftriaxone alone was ineffective. All implants treated with systemic ceftriaxone and local gentamicin were sterile (p < 0.001), the other groups were less effective. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1320–1326, 2015.     

Antimicrobial activity of platelet‐leukocyte gel against Staphylococcus aureus

Platelet‐leukocyte gel (PLG) contains high concentrations of platelets and leukocytes. As leukocytes play an important role in the innate host‐defense, we hypothesized that PLG might have antimicrobial properties. This study investigated the antimicrobial activity of PLG against Staphylococcus aureus and the contribution of myeloperoxidase (MPO), present in leukocytes, in this process. Platelet‐rich plasma (PRP) and platelet‐poor plasma (PPP) were obtained from whole blood of six donors. PLG was prepared by mixing PRP with autologous (PLG‐AT) or bovine thrombin (PLG‐BT). Antimicrobial activity of PLG‐AT, PLG‐BT, PRP, and PPP was determined in a bacterial kill assay. MPO release was measured by ELISA and activity was measured using a MPO activity assay. Cultures showed a rapid decrease in the number of bacteria for both PLG‐AT and PLG‐BT, which was maximal between 4 and 8 h, to approximately 1% of the bacteria in controls. The effect of PLG‐AT was largest and significantly different compared to PRP (p = 0.004) and PPP (p < 0.001), however not compared to PLG‐BT (p = 0.093). PLG‐AT, PLG‐BT, and PRP showed a comparable, gradually increasing MPO release. MPO activity was comparable for all groups and remained stable. No correlation between MPO release, activity, and bacterial kill could be found. PLG appears to have potent antimicrobial capacity, but the role of MPO in this activity is questionable. PLG might represent a useful strategy against postoperative infections. However, additional research should elucidate its exact antimicrobial activity. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:404–410, 2008     

Efficacy of antiseptics containing povidone‐iodine,octenidine dihydrochloride and ethacridine lactate against biofilm formed by Pseudomonas aeruginosa and Staphylococcus aureus measured with the novel biofilm‐oriented antiseptics test

Increasing data suggesting that microorganisms in the biofilm form are among the leading agents of persistent infections of chronic wounds require the development of new approaches to treatment. The aim of this article was to compare the efficacy of three commonly used antiseptics using a biofilm‐oriented approach. Biofilm‐oriented antiseptics test (BOAT), the innovative method, allows to estimate, in a quick and reliable manner, the in vitro activity of working solutions of antiseptics in real contact times against bacteria in the biofilm form and to use the results in the selection of an appropriate antiseptic to treat local infections in the clinical practice.     

Implant‐associated localized osteitis in murine femur fracture by biofilm forming Staphylococcus aureus: A novel experimental model

Staphylococcus aureus (SA) is the most common causative agent for implant‐associated osteitis. The present study characterizes a novel model of a low grade acute SA osteitis with bone defect in the femur which is stabilized by a titanium locking plate. Wild‐type Balb/c mice were osteotomized, fixed by a locking plate and infected with SA. Mice underwent debridement 7 and 14 days later and were sacrificed at Day 28. At Days 7, 14, and 28 after inoculation local and systemic cell populations and IL‐6 were analyzed. Fracture healing was quantified by radiography. The control group underwent the same procedure without infection. The bacterial load of implant‐associated osteitis with biofilm formation was quantified by counting CFU and real‐time PCR. Fracture healing determined by radiography was delayed in infected compared to non‐infected mice. Throughout the investigation period CFU and leukocyte counts, as well as IL‐6 levels were found to be significantly elevated in infected mice at the infection site but not systemically. Our murine model allows the detailed investigation of implant associated localized osteitis with biofilm producing SA and its influence on fracture healing. The model provides a tool to analyze therapeutic or prophylactic approaches to the problem of biofilm‐associated osteitis. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:2013–2020, 2013     

Influence of various treatments including povidone‐iodine and healing stimulatory reagents in a rabbit ear wound model

Selecting an appropriate treatment for a given case of skin wound is crucial for inducing optimal healing. We used an animal model developed from normal rabbit ears in order to assess the efficacy of treatments for skin wounds with or without a wet dressing, anti microbial reagent or topical wound‐stimulatory reagents. The degree of healing in each group was evaluated and compared using four histological parameters: (i) degree of reepithelialisation, (ii) amount of granulation tissue formation, and (iii) the number of capillary lumens and (iv) fibroblasts in the granulation tissue. Treatment using wet dressings resulted in an increase in capillary number compared with the open dry wound. Although the retention of povidone‐iodine (PI) in wound tissue after application significantly inhibited reepithelialisation (P < 0·05), rinsing PI off with saline was comparable in effect to using only a wet dressing. The three topical reagents, namely, basic fibroblast growth factor, prostaglandin E1 and dibutyryl cyclic adenosine monophosphate, significantly improved reepithelialisation (P < 0·05). In conclusion, wounds should be kept hydrated by applying topical reagents. If there are any signs of bacterial infection, PI can be applied and rinsed later with saline in order to minimise its cytotoxic effects.     

The AO trauma CPP bone infection registry: Epidemiology and outcomes of Staphylococcus aureus bone infection

Bone infection represents a serious complication of orthopedic surgery and Staphylococcus aureus is the most common pathogen. To improve the understanding of host‐pathogen interaction, we developed a biospecimen registry (AO Trauma CPP Bone Infection Registry) to collect clinical data, bacterial isolates, and serum from patients with S. aureus bone infection. A prospective multinational registry with a 12‐month follow‐up was created to include adult patients (18 years or older) with culture‐confirmed S. aureus infection in long bones after fracture fixation or arthroplasty. Baseline patient attributes and details on infections and treatments were recorded. Blood and serum samples were obtained at baseline, 6, and 12 months. Patient‐reported outcomes were collected at 1, 6, and 12 months. Clinical outcomes were recorded. Two hundred and ninety‐two patients with fracture‐related infection (n = 157, 53.8%), prosthetic joint infection (n = 86, 29.5%), and osteomyelitis (n = 49, 16.8%) were enrolled. Methicillin‐resistant S. aureus was detected in 82 patients (28.4%), with the highest proportion found among patients from North American sites (n = 39, 48.8%) and the lowest from Central European sites (n = 18, 12.2%). Patient outcomes improved at 6 and 12 months in comparison to baseline. The SF‐36 physical component summary mean (95% confidence interval) score, however, did not reach 50 at 12 months. The cure rate at the end of the study period was 62.1%. Although patients improved with treatment, less than two‐thirds were cured in 1 year. At 12‐month follow‐up, patient‐reported outcome scores were worse for patients with methicillin‐resistant S. aureus infections.     

Biofilm dispersal of community‐associated methicillin‐resistant Staphylococcus aureus on orthopedic implant material

Orthopedic implant‐related bacterial infections are associated with high morbidity that may lead to limb amputation and exert significant financial burden on the healthcare system. Staphylococcus aureus is a dominant cause of these infections, and increased incidence of community‐associated methicillin‐resistant S. aureus (CA‐MRSA) is being reported. The ability of S. aureus to attach to the foreign body surface and develop a biofilm is an important determinant of resistance to antibiotic prophylaxis. To gain insight on CA‐MRSA biofilm properties, USA300 biofilm maturation and dispersal was examined, and these biofilms were found to exhibit pronounced, quorum‐sensing mediated dispersal from a glass surface. For comparison of biofilm maturation on different surface chemistries, USA300 biofilm growth was examined on glass, polycarbonate, and titanium, and minimal differences were apparent in thickness, total biomass, and substratum coverage. Importantly, USA300 biofilms grown on titanium possessed a functional dispersal mechanism, and the dispersed cells regained susceptibility to rifampicin and levofloxacin treatment. The titanium biofilms were also sensitive to proteinase K and DNaseI, suggesting the matrix is composed of proteinaceous material and extracellular DNA. These studies provide new insights on the properties of CA‐MRSA biofilms on implant materials, and indicate that quorum‐sensing dispersion could be an effective therapeutic strategy. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:55–61, 2010     

Novel model for studying hematogenous infection in an experimental setting of implant‐related infection by a community‐acquired methicillin‐resistant S. aureus Strain

The aim of this study is to establish a new experimental model of hematogenous implant‐related infection (IRI) by a community‐acquired methicillin‐resistant S. aureus (CA‐MRSA) strain. Cylindrical porous tantalum intramedullary implants were inserted in the proximal right tibia of 30 male white rabbits after administration of antibiotic prophylaxis. Four weeks later and without antibiotic prophylaxis, 20 animals received 1 ml of inoculum of two different concentrations (study groups A and B) of CA‐MRSA strain through an ipsilatelar femoral artery catheter. The remaining 10 received normal saline instead (control group C). Surviving animals were sacrificed 4 weeks later. Sterile bone, bone marrow biopsies, and implants were harvested for culture and histological evaluation. Ten animals receiving 5 × 10⁸cfu/ml (group A) died within 48–72 h due to septic shock. Blood cultures were positive; histology demonstrated acute infection. Ten animals received bacterial load of 3 × 10⁸cfu/ml (group B) and all survived; two had negative Gram‐stain and cultures but PCR and RT‐PCR results demonstrated the viability of the microorganisms, while periprosthetic osteolysis and histological evaluation indicated subacute osteomyelitis; eight animals established periprosthetic infection, osteomyelitis, and septic arthritis documented by positive Gram‐stain, cultures, subperiosteal reaction, and chronic infection on histology. Control group specimens demonstrated no signs of infection. Histopathological semiquantitative scoring was used to compare the three groups. Comparison of groups A and B with control group and between group A and B showed statistically significant difference (p < 0.05) in all parameters except for periosteal reaction between groups B and C (p = 0.354). This novel, reproducible experimental model will facilitate the study of hematogenous CA‐MRSA IRIs. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1355–1362, 2008     

Biofilm formation increases treatment failure in Staphylococcus epidermidis device‐related osteomyelitis of the lower extremity in human patients

The ability to form biofilm on the surface of implanted devices is often considered the most critical virulence factor possessed by Staphylococcus epidermidis in its role as an opportunistic pathogen in orthopaedic device‐related infection (ODRI). Despite this recognition, there is a lack of clinical evidence linking outcome with biofilm forming ability for S. epidermidis ODRIs. We prospectively collected S. epidermidis isolates cultured from patients presenting with ODRI. Antibiotic resistance patterns and biofilm‐forming ability was assessed. Patient information was collected and treatment outcome measures were determined after a mean follow‐up period of 26 months. The primary outcome measure was cure at follow‐up. Univariate logistic regression models were used to determine the influence of biofilm formation and antibiotic resistance on treatment outcome. A total of 124 patients were included in the study, a majority of whom (n = 90) involved infections of the lower extremity. A clear trend emerged in the lower extremity cohort whereby cure rates decreased as the biofilm‐forming ability of the isolates increased (84% cure rate for infections caused by non‐biofilm formers, 76% cure rate for weak biofilm‐formers, and 60% cure rate for the most marked biofilm formers, p = 0.076). Antibiotic resistance did not influence treatment cure rate. Chronic immunosuppression was associated with a statistically significant decrease in cure rate (p = 0.044). Clinical significance: The trend of increasing biofilm‐forming ability resulting in lower cure rates for S. epidermidis ODRI indicates biofilm‐forming ability of infecting pathogens does influence treatment outcome of infections of the lower extremity. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1905–1913, 2016.     

Effects of vancomycin,daptomycin, fosfomycin,tigecycline, and ceftriaxone on Staphylococcus epidermidis biofilms

Infection of medical implanted material is associated with considerable morbidity and costs. In the following work, we investigated the effects of vancomycin, daptomycin, fosfomycin, tigecycline, and ceftriaxone on biofilms formed by Staphylococcus epidermidis isolates causative for implant infection and catheter‐associated bacteremia. Biofilms were studied using the static microtiter plate model and incubated with the antibiotics increasing the concentration from 1× to 128× the minimal inhibitory concentration (MIC) of the respective isolate tested. To quantify the reduction of the biomass, the optical density ratio (ODr) of stained biofilms and the number of growing bacteria were determined. Incubation of the staphylococcal biofilms with the antibiotics decreased the biofilm ODr (at baseline = 1) for ceftriaxone (0.83 ± 0.48) but minimally only for fosfomycin (0.96 ± 0.64), daptomycin (1.05 ± 0.59), tigecycline (1.18 ± 0.66), and vancomycin (0.98 ± 0.44) at exceedingly high concentrations of 128 × MIC. The significant reduction of the bacterial growth was not achieved for all antibiotics, not even at the highest concentrations tested. Using higher doses of the antibiotics may be of some value in the treatment of biofilm‐associated infections, although effects are seen only at clinically unachievable doses. However, to eradicate the staphylococcal biofilm, additional measures like debridement and/or removal of the implant are needed. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1361–1365, 2009     

EPA covalently bound to smooth titanium surfaces decreases viability and biofilm formation of Staphylococcus epidermidis in vitro

Colonization of implant surfaces with bacteria should ideally be prevented right from implantation, as bacteria attaching to the surface will form a biofilm, being then well protected against antibiotic treatment. Therefore, implant coatings should combine antibacterial properties with biocompatibility towards their host tissue. We tested a UV‐induced covalent coating procedure with eicosapentaenoic acid (EPA) for smooth titanium (Ti) surfaces for its ability to prevent attachment and proliferation of Staphylococcus epidermidis and to allow mineralization of MC3T3‐E1 osteoblasts. Bacterial initial attachment was highest for EPA‐coated surfaces, but was reduced by vigorous washing, possibly due to low adhesive strength on those surfaces. We found an increase in the ratio of dead bacteria and in overall biofilm after 16 h on Ti surfaces with covalently bound EPA compared to Ti. The UV‐induced EPA coating did not impair the ability of MC3T3‐E1 preosteoblasts to mineralize, while a reduction in mineralization could be found for UV‐irradiated Ti surfaces and UV‐irradiated surfaces washed with ethanol compared to Ti. Although in vivo studies are needed to evaluate the clinical significance, our results indicate that covalent coating of Ti surfaces with EPA by UV irradiation decreases the survival of S. epidermidis and maintains the mineralization ability of osteoblasts. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1384–1390, 2012     

Lugol's solution and Gentian violet eradicate methicillin‐resistant Staphylococcus aureus biofilm in skin wound infections

The study aimed to evaluate the antibacterial efficacy of Lugol''s solution 5% and Gentian violet 1% against methicillin‐resistant Staphylococcus aureus (MRSA) biofilm in vivo. The bactericidal efficacy for treatment of MRSA‐biofilm skin wound infection was tested in a murine model. Luciferase‐tagged S. aureus Xen31, a MRSA‐strain derived from S. aureus ATCC‐3359130, was used for infection. Wounds were made in the skin of mice and infected with MRSA. The mice were treated with Lugol''s solution and Gentian violet. Application of the antimicrobial agents started 24 hours post infection and was repeated daily for five‐days. The antimicrobial effect on the biofilm bacteria was evaluated by measuring bioluminescence from MRSA daily for seven‐days. Lugol''s solution and Gentian violet showed a significant reduction in luminescent signals from the first assessment day to all subsequent days (P < .001). Lugol''s solution and Gentian violet effectively eradicated MRSA in biofilm in vivo and could be alternatives or in addition to topical antibiotics when MRSA‐biofilm wound infection is suspected.     

Management of non‐healable or maintenance wounds with topical povidone iodine

Although complete healing may appear to be the logical goal for most patients and clinicians, some wounds do not have the potential to heal due to a number of factors such as inadequate vasculature, coexisting medical conditions and medications that prohibit the healing process. Local management of wounds that are considered to have poor potential for healing remains elusive. The purpose of this article is to review the evidence that supports the use of topical antiseptic agents in non‐healable wounds. Retrospective chart audit was conducted to evaluate the use of povidone iodine in the management of wounds that were deemed to have poor healing potential.     

Protective role of IL‐1β against post‐arthroplasty Staphylococcus aureus infection

MyD88 is an adapter molecule that is used by both IL‐1R and TLR family members to initiate downstream signaling and promote immune responses. Given that IL‐1β is induced after Staphylococcus aureus infections and TLR2 is activated by S. aureus lipopeptides, we hypothesized that IL‐1β and TLR2 contribute to MyD88‐dependent protective immune responses against post‐arthroplasty S. aureus infections. To test this hypothesis, we used a mouse model of a post‐arthroplasty S. aureus infection to compare the bacterial burden, biofilm formation and neutrophil recruitment in IL‐1β‐deficient, TLR2‐deficient and wild‐type (wt) mice. By using in vivo bioluminescence imaging, we found that the bacterial burden in IL‐1β‐deficient mice was 26‐fold higher at 1 day after infection and remained 3‐ to 10‐fold greater than wt mice through day 42. In contrast, the bacterial burden in TLR2‐deficient mice did not differ from wt mice. In addition, implants harvested from IL‐1β‐deficient mice had more biofilm formation and 14‐fold higher adherent bacteria compared with those from wt mice. Finally, IL‐1β‐deficient mice had ～50% decreased neutrophil recruitment to the infected postoperative joints than wt mice. Taken together, these findings suggest a mechanism by which IL‐1β induces neutrophil recruitment to help control the bacterial burden and the ensuing biofilm formation in a post‐surgical joint. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 1621–1626, 2011     

碘伏联合过氧化氢溶液口腔护理预防重型颅脑损伤患者并发肺部感染

目的探讨应用碘伏联合过氧化氢溶液进行口腔护理预防重型颅脑损伤患者并发肺部感染的效果。方法将158例重型颅脑损伤患者按Glasgow昏迷评分相同分为两组各79例。观察组采用0.05%碘伏进行口腔擦洗,2次/d,当评估口腔内有血痂或痰痂时,先用0.5%过氧化氢溶液湿润血痂或痰痂,再使用碘伏进行口腔擦洗;对照组采用0.02%醋酸氯己定溶液口腔擦洗,2次/d。结果口腔干预后第8天观察组咽拭子和痰标本细菌培养阳性率以及肺部感染发生率显著低于对照组(均P<0.05)。结论应用0.05%碘伏必要时加用0.5%过氧化氢溶液为重型颅脑损伤患者进行口腔护理能有效消除口咽部致病菌,降低肺部感染发生率。     

Quantifying the natural history of biofilm formation in vivo during the establishment of chronic implant‐associated Staphylococcus aureus osteomyelitis in mice to identify critical pathogen and host factors

While it is well known that Staphylococcus aureus establishes chronic implant‐associated osteomyelitis by generating and persisting in biofilm, research to elucidate pathogen, and host specific factors controlling this process has been limited due to the absence of a quantitative in vivo model. To address this, we developed a murine tibia implant model with ex vivo region of interest (ROI) imaging analysis by scanning electron microscopy (SEM). Implants were coated with Staphylococcus aureus strains (SH1000, UAMS‐1, USA300LAC) with distinct in vitro biofilm phenotypes, were used to infect C57BL/6 or Balb/c mice. In contrast to their in vitro biofilm phenotype, results from all bacteria strains in vivo were similar, and demonstrated that biofilm on the implant is established within the first day, followed by a robust proliferation phase peaking on Day 3 in Balb/c mice, and persisting until Day 7 in C57BL/6 mice, as detected by SEM and bioluminescent imaging. Biofilm formation peaked at Day 14, covering ～40% of the ROI coincident with massive agr‐dependent bacterial emigration, as evidenced by large numbers of empty lacunae with few residual bacteria, which were largely culture negative (80%) and PCR positive (87.5%), supporting the clinical relevance of this implant model. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1311–1319, 2015.