Comparison of silver sulfadiazine and gentamicin for topical prophylaxis against burn wound sepsis.

Daily prophylactic application of either 1.0% silver sulfadiazine cream or 0.1% gentamicin cream was compared for effectiveness in preventing bacterial colonization of burn wounds and sepsis. Pseudomonas aeruginosa colonized the wounds of 37% of the 38 patients treated with silver sulfadiazine and 30% of the 33 patients treated with gentamicin; gentamicin-resistant P. aeruginosa colonized the wounds of 21% of the patients treated with gentamicin. Staphylococcus aureus colonization occurred in 55% of the patients treated with silver sulfadiazine, whereas colonization with Candida species occurred in 58% of the patients treated with gentamicin. Although gentamicin-resistant organisms caused no deaths their repeated appearance resulted in discontinuation of prophylaxiz with gentamicin cream. The next year P. aeruginosa strains resistant to gentamicin were isolated from burn wounds of only two patients who had not previously received parenteral therapy with gentamicin or tobramycin. Gentamicin cream should be reserved for treating patients with wounds infected by gentamicin-sensitive P. aeruginosa and those allergic to sulfa drugs. For most patients with burn wounds silver sulfadiazine is safe and effective as an antibacterial agent for topical prophylaxis.     

Photodynamic therapy for Staphylococcus aureus infected burn wounds in mice.

The rise of multiply antibiotic resistant bacteria has led to searches for novel antimicrobial therapies to treat infections. Photodynamic therapy (PDT) is a potential candidate; it uses the combination of a photosensitizer with visible light to produce reactive oxygen species that lead to cell death. We used PDT mediated by meso-mono-phenyl-tri(N-methyl-4-pyridyl)-porphyrin (PTMPP) to treat burn wounds in mice with established Staphylococcus aureus infections The third degree burn wounds were infected with bioluminescent S. aureus. PDT was applied after one day of bacterial growth by adding a 25% DMSO/500 microM PTMPP solution to the wound followed by illumination with red light and periodic imaging of the mice using a sensitive camera to detect the bioluminescence. More than 98% of the bacteria were eradicated after a light dose of 210 J cm(-2) in the presence of PTMPP. However, bacterial re-growth was observed. Light alone or PDT both delayed the wound healing. These data suggest that PDT has the potential to rapidly reduce the bacterial load in infected burns. The treatment needs to be optimized to reduce wound damage and prevent recurrence.     

The role of nasal carriage in Staphylococcus aureus burn wound colonization

Thermal injury destroys the physical skin barrier that normally prevents invasion of microorganisms. This and concomitant depression of local and systemic host cellular and humoral immune responses are important factors that contribute to colonization and infection of the burn wound. One of the most common burn wound pathogens is Staphylococcus aureus. Staphylococcus aureus is both a human commensal and a frequent cause of infections leading to mild to life-threatening diseases. Despite a variety of infection control measures, for example patient cohorting and contact precaution at burn centres, S. aureus is still frequently encountered in burn wounds. Colonization with S. aureus has been associated with delayed wound healing, increased need for surgical interventions, and prolonged length of stay at burn centres. In this minireview, we focus on S. aureus nasal carriage in relation to S. aureus burn wound colonization and subsequent infection, and its impact on strategies for infection control.     

烫伤创面绿脓杆菌定植动态的实验研究

本文从细菌以多细胞生理活动观点出发,以认识定植稳定过程为目的。进行了实验大白鼠烫伤创面绿脓杆菌定植与抗定植动态观察。通过用铁浸染色法对细菌群体结构定量化研究,用糖包被负染法对群体结构内部结构观察,对粘附在组织表面细菌数量的测定,反映结构与粘附力的关系。进一步结合电镜观察及细菌生长状态的分析,证明了烫伤创面上绿脓杆菌群体结构的形成是细菌分裂繁殖所致。通过群体结构,糖包被,粘附力及生长状态的动态观察,表现出与定植的稳定程度呈平行关系,显示其重要性。联系抗定植力研究,表明定植与抗定植的一致性。最后分析了定植三个主要条件,和稳定性定植的三要素。     

Wound fluid bacterial levels exceed tissue bacterial counts in controlled porcine partial-thickness burn infections

In the present study, an established controlled burn wound model was used to test the hypothesis that controlled surface contamination with is capable of generating a noninvasive method for the creation of a reproducible deep tissue burn wound infection. Using a liquid tight-wound chamber in Yorkshire pigs, partial-thickness burns were inoculated with saline-immersed for 24 hours. Noninoculated burns and unwounded skin immersed in normal saline served as controls. Bacterial cultures of wound fluid were performed daily, and tissue biopsies for bacteriological and histological evaluations were performed on days 1, 3, and 5. was only recovered from -inoculated wounds (tissue and fluid), whereas all controls contained endogenous only. The number of colony-forming units per gram of wound tissue did not correlate with the bacterial counts found in the overlying wound fluid for any wounds. Fluid counts were consistently higher than tissue counts by two logs. -inoculated wounds showed three times deeper tissue destruction than control wounds. Obtaining consistently deep tissue colonization without cross-contamination among wounds, this study introduces a noninvasive model for controlled burn wound infection suitable for future investigations regarding the efficacy of topical antibiotic wound treatment in experimental burns.     

Enhancement of dendritic cell production by fms-like tyrosine kinase-3 ligand increases the resistance of mice to a burn wound infection

Fms-like tyrosine kinase-3 ligand (Flt3L) is a hemopoietic cytokine that stimulates the production of dendritic cells. This study evaluated the ability of Flt3L-enhanced dendritic cell production to increase the resistance of mice to a burn wound infection with Pseudomonas aeruginosa, a common source of infections in burn patients that have impaired immunity and are susceptible to opportunistic microorganisms. Treatment of mice with Flt3L for 5 days caused a significant increase in dendritic cell numbers in the spleen and significantly increased survival upon a subsequent burn wound infection. Improved survival in Flt3L-treated mice was associated with limited bacterial growth and spread within the burn wounds and a decrease in systemic dissemination of P. aeruginosa. Resistance to burn wound infection could also be conferred to recipient mice by the adoptive transfer of dendritic cells that had been isolated from spleens of Flt3L-treated mice. Adoptive transfer of the same number of splenic dendritic cells from nontreated mice did not confer resistance to burn wound infection. These data indicate that Flt3L can increase the resistance of mice to a P. aeruginosa burn wound infection through both stimulation of dendritic cell production and enhancement of dendritic cell function.     

Innate defense regulator Peptide 1018 in wound healing and wound infection

Innate defense regulators (IDRs) are synthetic immunomodulatory versions of natural host defense peptides (HDP). IDRs mediate protection against bacterial challenge in the absence of direct antimicrobial activity, representing a novel approach to anti-infective and anti-inflammatory therapy. Previously, we reported that IDR-1018 selectively induced chemokine responses and suppressed pro-inflammatory responses. As there has been an increasing appreciation for the ability of HDPs to modulate complex immune processes, including wound healing, we characterized the wound healing activities of IDR-1018 in vitro. Further, we investigated the efficacy of IDR-1018 in diabetic and non-diabetic wound healing models. In all experiments, IDR-1018 was compared to the human HDP LL-37 and HDP-derived wound healing peptide HB-107. IDR-1018 was significantly less cytotoxic in vitro as compared to either LL-37 or HB-107. Furthermore, administration of IDR-1018 resulted in a dose-dependent increase in fibroblast cellular respiration. In vivo, IDR-1018 demonstrated significantly accelerated wound healing in S. aureus infected porcine and non-diabetic but not in diabetic murine wounds. However, no significant differences in bacterial colonization were observed. Our investigation demonstrates that in addition to previously reported immunomodulatory activities IDR-1018 promotes wound healing independent of direct antibacterial activity. Interestingly, these effects were not observed in diabetic wounds. It is anticipated that the wound healing activities of IDR-1018 can be attributed to modulation of host immune pathways that are suppressed in diabetic wounds and provide further evidence of the multiple immunomodulatory activities of IDR-1018.     

树鼩细菌感染模型的建立及抗菌药物的治疗效果评价(英文)

在抗微生物感染药物开发过程中, 动物模型是必不可少的。虽然目前已经用啮齿类动物建立了一些细菌感染动物模型, 但在小型灵长类动物中还很少见。这里首次报道两个树鼩细菌感染动物模型。第一种是在三度烫伤后的皮肤表面接种 5×106 CFU 的金黄色葡萄球菌构建的皮肤烫伤感染模型。这个数量的金黄色葡萄球菌可以造成 7 d 持续性感染, 并且在第 4天可以看到明显的炎症反应。第二种是用绿脓杆菌构建的涤纶补片感染模型, 接种 2×106 CFU 的绿脓杆菌同样可以引起持续 6 d 感染, 并在第三天在伤口处观察到大量的脓液。进一步用这两种模型评价头孢哌酮钠和左氧氟沙星的治疗效果。左氧氟沙星和头孢哌酮钠在皮肤烫伤感染模型中能分别将 100 mg 皮肤组织中的细菌降低到 4log10 和 5log10 CFU, 并且在涤纶补片植入感染模型中这两种抗生素都能显著地将感染的细菌降低了 4log10 CFU (P<0.05)。结果表明用金黄色葡萄球菌和绿脓杆菌成功构建了两个细菌感染的树鼩模型。此外, 树鼩对金黄色葡萄球菌和绿脓杆菌很敏感, 适合用于构建细菌感染动物模型和评价新的抗细菌感染药物的效果。     

烧烫伤创面感染的小鼠模型构建

目的探讨一种简单、稳定的烧烫伤创面感染的小鼠模型构建方法,以便进行相关烧烫伤创面修复研究。方法取30只BALB/c小鼠,采用自制木质烫伤板,沸水浴法烫取直径8 mm的圆形创面,烫伤时间分别为5 s、10 s、15 s。伤后48 h,取创面组织进行HE染色观察,筛选最佳创面烫伤时间。另取72只小鼠制成深Ⅱ度烫伤创面,采用擦刮法分别接种20μL菌浓度为1×106、l×107、1×108CFU/mL金黄色葡萄球菌标准菌株ATCC 25923的菌液。接种细菌后72 h,取创面组织HE染色观察创面炎症反应情况,并测定3、7、14 d的皮肤菌负荷,筛选最佳的细菌接种浓度。最后,按最佳条件建模后,观察创面的完全愈合时间以及创面愈中、愈后的组织学变化,以确定此创面感染模型是否建立成功。结果组织学结果表明,10 s为深Ⅱ度创面的理想致伤时间,最佳接种菌浓度为l×108CFU/mL,此时期,14 d内菌负荷均高于l×105CFU/g。该模型的创面愈合时间(21±0.95 d)较正常创面愈合时间(15.92±0.34 d)明显延长(P<0.01),炎性反应明显,愈后不佳。结论烧烫伤创面感染的小鼠模型构建成功,可作为感染创面防治研究的实验动物模型。     

Induction of antibacterial activity in larvae of the blowfly Lucilia sericata by an infected environment

Maggot debridement therapy (MDT) is a method for the treatment of intractable, infected and necrotic wounds. In MDT, sterile larvae of Lucilia sericata Meigen (Diptera: Calliphoridae) are applied to infected wounds, where they exert antibacterial effects. Once the larvae are placed in the wound, they are no longer germ-free. This study analysed the influence of infected environments on larval antibacterial activities. Sterile larvae were mixed in a test tube containing a bacterial suspension of Staphylococcus aureus or Pseudomonas aeruginosa, transferred to liver puree agar, and incubated at 25 °C for set periods. To collect the larval extracts, the incubated larvae were transferred to a test tube containing phosphate buffered saline (PBS), cut into multiple pieces with scissors, and centrifuged. The supernatant was used to test antibacterial activities. The results showed that infected larvae had better antibacterial capacities than sterile larvae. Antibacterial activities were induced by pretreatment with a single bacterial species, S. aureus or P. aeruginosa, within 24 h and 12 h, respectively, and disappeared after 36 h. The activities were effective against S. aureus, but not against P. aeruginosa. This natural infection model is very similar to the clinical wound context in MDT and will be a powerful tool with which to study the antibacterial activities of L. sericata larvae in MDT.     

Improvement in burn wound infection and survival with antimicrobial peptide D2A21 (Demegel)

Naturally occurring antimicrobial peptides have been discovered in both plants and animals. Many of these peptides demonstrate impaired activity or cytotoxicity when applied exogenously. Synthetically engineered antimicrobial peptides have been designed to increase potency and activity against bacteria and fungus yet remain noncytotoxic. The antimicrobial peptide D2A21 (Demegel) has already demonstrated significant activity in vitro against many common hospital pathogens. The purpose of this study was to evaluate the effects of D2A21 in an in vivo infected burn-wound model, examining both quantitative cultures of the wound and survival of the animal. Forty-four Wistar rats were subjected to a 23 percent total body surface area scald burn. Pseudomonas aeruginosa was administered topically with 108 organisms and wounds were then evaluated at day 1, 2, or 3 for eschar and subeschar muscle quantitative culture. The experimental group was treated daily with 1.5% topical D2A21. The control group was treated with control gel. A second group of Wistar rats (n = 14) were burned and given a 107 inoculum of the same Pseudomonas and evaluated to 14 days for survival and weight changes. This group was subdivided into rats receiving either topical D2A21 or control base daily. The quantitative biopsy results demonstrated that D2A21-treated wounds had no bacterial growth in burn eschar at day 2 or 3, whereas control animals demonstrated growth at greater than 105 organisms by day 2. Subeschar muscle cultures also demonstrated significantly less bacterial invasion compared with controls on each day tested. D2A21-treated animals had an 85.7 percent survival compared with 0 percent survival in controls. Furthermore, the D2A21-treated groups demonstrated maintenance of body weights, whereas controls had significant weight loss with time. In conclusion, D2A21 demonstrates significant antibacterial activity against Pseudomonas, sterilizing burn eschar and decreasing subeschar bacterial load, allowing for a markedly significant improvement in survival in this infected burn-wound model.     

A novel titanium wound chamber for the study of wound infections in pigs

In the face of emerging multidrug-resistant microbes, reliable animal models are needed to study potential new therapies in infected wounds. To this end, we implanted screw-top titanium chambers subdermally in full-thickness wounds on both flanks (n = 6 per flank) of 2 Goettinger minipigs. After 1 wk, chambers were inoculated with Staphylococcus aureus, Pseudomonas aeruginosa, or vehicle only. Throughout the study, wound fluid was harvested for quantitative bacterial cultures to monitor infection. Animals were followed for 4 wk, after which tissue biopsies were taken for histologic analysis and quantitative bacterial counts. The implanted titanium chambers were well tolerated by the pigs throughout the study. After inoculation of the chambers, wound infection was established and maintained for 14 d. Despite infection, no systemic effects were noted. Cross-contamination was negligible, compared with the vehicle-only control. After tissue ingrowth, each chamber creates a closed system that allows harvest of exudate or application of substances without loss of material from the chamber. Because 12 chambers are implanted in each pig, researchers have the opportunity to compare multiple treatment options (for example, antibiotics, antimicrobial peptides, gene therapy) in the same animal, with no interindividual variation. We conclude that the use of titanium chambers in pigs provides a reliable and reproducible in vivo model to investigate wound healing, wound infection, and treatment options.     

乳酸杆菌代谢产物对引起阴道炎常见细菌的抑制作用的初步探讨

目的探讨乳酸杆菌代谢产物对临床常见引起阴道炎的大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、白色念珠菌、伤寒杆菌和肠球菌的抑菌作用。方法采用营养琼脂平板培养基定量涂菌,国际标准药敏杯给药的药敏试验法,检测乳酸杆菌代谢产物对大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、白色念珠菌、伤寒杆菌和肠球菌的抑菌环的大小。结果乳酸杆菌代谢产物对大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌和伤寒杆菌有明显的抑菌作用,对肠球菌、白色念珠菌无抑菌作用。结论在临床上可应用乳酸杆菌及其制剂调节阴道微生态平衡,治疗细菌性阴道炎。     

Antimicrobial and membranolytic activities of anti-burn drug fenozan]

Fenozan, an anti-burn preparation, was shown to have antimicrobial activity against freshly isolated clinical strains of Staphylococcus aureus and Streptococcus faecalis, as well as against collection strains of the other gram-positive bacteria. The antimicrobial action of the preparation was possibly due to impairment of permeability of the cytoplasmic membranes in the sensitive bacterial cells and their liberation of intracellular low molecular weight compounds to the environment. The membranolytic and minimum inhibitory concentrations of fenozan with respect to the sensitive bacterial cells were one order of magnitude lower than the concentration stabilizing the membranes of animal cells in the treatment of burns. Combination of the antioxidant and antimicrobial properties in fenozan was likely to provide its satisfactory therapeutic effect in the treatment of burn wounds.     

ICU气管切开患者下呼吸道定植菌分析及防治对策

目的了解重症监护病房气管切开患者下呼吸道定植菌(lower airway bacterial colonization,LABC)的病原菌分布和耐药谱,为临床诊断LABC提供参考依据,防止定植菌转变为致病菌提供临床防治方法。方法入选2008年10月至2011年6月入住ICU气管切开患者下呼吸道进行支气管肺泡灌洗,并对灌洗液进行细菌定量培养及抗菌药物敏感性测定。结果 180例气管切开患者LABC检出率高达85.2%,培养出定植菌232株,以革兰阴性菌(G-)为主,占78.8%,其中铜绿假单胞菌62株,居首位占26.7%;肺炎克雷伯杆菌36株,居第2占15.5%;其次为鲍曼不动杆菌(占12.1%)、大肠埃希菌(占8.2%)、洋葱伯克霍尔德菌(占4.3%)和嗜麦牙寡养单胞菌(占3.4%)。革兰阳性菌(G+)占14.7%,主要为金黄色葡萄球菌;真菌占6.5%,主要为白色假丝酵母菌属。耐药监测结果显示,革兰阴性菌均出现较强的耐药性。结论加强对气管切开患者LABC的监测与控制,加强肺部综合护理才能防止定植菌转变为致病菌,减少再次感染的发生。     

Effects of burn wound excision on bacterial colonization and invasion

Rates of survival after thermal injury have improved in the past two decades, and rates of wound infections and sepsis have decreased during the same period. Early excision has been advocated as one of the major factors, but its safety and efficacy and the exact timing of burn excision are still under debate. It was hypothesized that acute burn wound excision (in the first 24 hours after burning) would be superior to conservative treatment and delayed excision in preventing bacterial colonization and invasion. Twenty consecutive patients with thermal injuries were studied. Twelve patients underwent acute burn wound excision, and eight patients underwent conservative treatment and delayed excision. The second group of patients received topical treatments in another facility and underwent delayed excision after transfer to our service, on postburn day 6. Quantitative bacteriological assessments of the excised wound and biopsy samples of the wound bed, obtained before autografting and/or homografting, were performed. The effects of time on bacterial counts, differences between superficial and deep biopsy samples, and the effects of early versus late debridement were studied. Patients admitted early exhibited bacterial counts of less than 10 bacteria per gram of tissue. Patients in this group did not experience infection or graft loss. Patients admitted late exhibited counts of more than 10 bacteria (p = 0.001, compared with early admission). Three patients in the late excision group experienced infection and graft loss (p < 0.05, compared with the early excision group). Burn wound excision significantly decreased bacterial colonization for all patients (p < 0.001). Greater bacterial colonization and higher rates of infection were correlated with topical treatment and late excision (p < 0.001). It is concluded that burn wound excision significantly reduces bacterial colonization. Patients who undergo topical treatment and delayed burn wound excision exhibit greater bacterial colonization and increased rates of infection. Acute burn wound excision should be considered for all full-thickness burns.     

The lactoperoxidase system: the influence of iodide and the chemical and antimicrobial stability over the period of about 18 months

The lactoperoxidase (LP) system is a natural antimicrobial system, the use of which has been suggested as a preservative in foods and pharmaceuticals. The effect of adding iodide to the LP system, the chemical stability and the change in antimicrobial effectiveness during storage was studied. Addition of iodide with thiocyanate increased the fungicidal and bactericidal effect against Candida albicans, Escherichia coli and Staphylococcus aureus. Pseudomonas aeruginosa showed the same inhibition in the LP system with iodide and without iodide. Storage of the LP system in completely filled airtight containers for 18 months caused a 35% loss of the initial thiocyanate concentration. The antimicrobial activity of this LP system was strong enough to kill inocula of 106 cfu ml-1 of the four test organisms within 2 h of contact time. During storage of the air-containing LP system, the concentration of thiocyanate was reduced below detection limit within 7 d, the concentrations of hypothiocyanite and hypoiodite within 350 d. After 516 d the antimicrobial activity of air-containing LP system was strong enough to kill inocula of 106 cfu ml-1 Ps. aeruginosa within 2 h, Staph. aureus within 4 h and Candida albicans and E. coli within 1 week of contact time.     

Our Clinical Experience using Cryopreserved Cadaveric Allograft for the Management of Severe Burns

Human cadaveric allograft is the most commonly used alternative wound closure material for excised burn wounds when limited donor sites or the overall patient condition does not permit immediate grafting with autologous skin. The Skin Bank in Singapore has supplied a total of 33,000 cm² of cryopreserved cadaveric allograft to the Burns Centre in Singapore for the early post-burn treatment of 17 severely burned patients with body surface area (BSA) burn wounds averaging 58% (range 33–90). An average of 13% (range 3–30%) cadaveric allograft was transplanted on 17 patients. Seven patients had recovered from their burn injuries and ten patients died of multiple complications related to their burn injuries. Our clinical observation has shown good adherence of cadaveric allograft when applied on clean and debrided wound bed after 4–7 days of post-operation. The availability of cadaveric allograft permits early excision and wound coverage before the patients' condition is further compromised. Our clinical experience using cryopreserved cadaveric allograft is proving to be indispensable in the management of patients with severe burns. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of selected factors on the course of wound healing after surgery for laryngeal neoplasms

Finding of the a etiologic factors and participation of bacteria flora in wound healing in laryngeal cancer treatment was the purpose of our study. Investigations were performed in 27 patients. Swabs were taken from the postoperative wounds. Detailed identifications of the bacteria flora and antibiotic susceptibility of bacteria were performed. Wound healing was estimated according to extension of the carcinoma, applied antibiotics, state of the oral cavity, the kind of bacteriological flora isolated after surgical treatment from postoperative wounds. It was found that wound healing depended on the extension of carcinoma, as well as, type of isolated bacteria and antibiotic therapy used. The proper healing of postoperative wounds was not dependent on the state of the oral cavity and the dentition. The main cause of postoperative complication of wounds was methicillin-resistant Staphylococcus aureus (MRSA).