Redesign of portable suction equipment cases: an engineering approach to a disinfection problem.

BACKGROUND: Patients with tracheostomies carry a case for suctioning supplies. A returned case cultured positive for Staphylococcus aureus even after it had been cleaned with a disinfectant. The purposes of this study were to determine (1) the source of the S aureus and (2) how to provide a microbiologically safe case for the next patient. METHODS: Reviews of patient and environmental cultures plus pulsed-field gel electrophoresis (PFGE) were used to determine the source of the S aureus. Repeated wiping with various detergents/disinfectants did not remove the S aureus from the case, which could not be immersed for cleaning because of a chipboard component. We designed a case made of denim with a washable synthetic fiber to provide shape. The new cases were purposefully contaminated and laundered and then cultured. RESULTS: PFGE indicated that the S aureus was from the patient who had most recently used the case. Contamination of the denim case with the original S aureus, followed by laundering, resulted in a case that was free of the S aureus. These results were repeated for other pathogens. CONCLUSION: Commercially available cases for suction equipment can become contaminated with pathogens from the user and may be difficult to disinfect. By making the case out of washable materials, less expensive cases, which could be readily disinfected, resulted.

A microbiologic study of enteral feeding hang time in a burn hospital: can feeding costs be reduced without compromising patient safety?

BACKGROUND: Procedural changes for hospitalized patients must always balance safety with fiscal constraints. Microbiologic contamination of enteral feeding solutions has been previously associated with nosocomial infections. Formula manipulation and hang time contribute to microbial load, and there is considerable variation in hang time recommendations in the medical literature. With cost containment in mind, the purpose of this performance improvement study was to determine if an increase in hang time of a modular tube feeding product would increase microbial load or affect the nosocomial infection rate in pediatric burn patients. METHODS: This biphasic trial initially evaluated the microbial load of the feeding after delivery of two 4-hour aliquots into a container using the same delivery set (total hang time of 8 hours; number of tests = 20). Second, once this feeding procedure was deemed microbiologically safe, tube feedings were administered to patients, and both microbial load and nosocomial infection rate were monitored for 1 year. RESULTS: Contamination levels at the end of the 8-hour period using the same feeding set with 2 consecutive 4-hour feeding aliquots (number of tests = 38) were lower than standard recommendations. The hospital's nosocomial infection rate was not altered by this procedural change, and feeding-set expenses were reduced. CONCLUSIONS: The hang time of our enteral feeding administration set can be increased safely from 4 hours to 8 hours, with the tube feeding preparation added as two 4-hour aliquots without a significant change in microbial load or nosocomial infection rate, thus promoting simultaneous fiscal responsibility and patient safety.

Computer equipment used in patient care within a multihospital system: recommendations for cleaning and disinfection.

Computer hardware has been implicated as a potential reservoir for infectious agents. Leaders of a 22-hospital system, which spans North America and serves pediatric patients with orthopedic or severe burns, sought to develop recommendations for the cleaning and disinfection of computer hardware within its myriad patient care venues. A task force comprising representatives from infection control, medical affairs, information services, and outcomes management departments was formed. Following a review of the literature and of procedures within the 22 hospitals, criteria for cleaning and disinfection were established and recommendations made. The recommendations are consistent with general environmental infection control cleaning and disinfection guidelines, yet flexible enough to be applicable to the different locales, different computer and cleaning products available, and different patient populations served within this large hospital system.

Passive anti-PcrV treatment protects burned mice against Pseudomonas aeruginosa challenge.

The type III secretion system consists of secreted exoproducts and structural components, such as PcrV, and this system plays an important role in the virulence of Pseudomonas aeruginosa in burned hosts. The purpose of this study was to determine if passive anti-PcrV treatment would protect burned mice from fatal P. aeruginosa challenge, and to determine the type III exoproduct phenotype of the P. aeruginosa used as challenge strains. Antiserum was raised in rabbits. Mice were given a third degree burn, challenged with a lethal dose of P. aeruginosa, and treated with either anti-PcrV or control immunoglobulin intraperitoneally. Protection against three different pseudomonads was tested. Genotyping by PCR and phenotyping by immunoblots showed the P. aeruginosa strains to all be of the invasive type III phenotype: ExoS+ and/or ExoT+, ExoU-, ExoY+. Against all strains, the anti-PcrV treatment yielded significantly better survival (p<0.05) than the control immunoglobulin treatment. Duration of significant protection was improved by giving a second injection of PcrV antisera at 24h postburn. Hence, passive anti-PcrV immunization could protect burned mice against fatal challenge with P. aeruginosa of an invasive type III phenotype. This immunotherapy might be explored further as possible treatment for highly antibiotic resistant P. aeruginosa infections in burned hosts.

Evaluation of cytotoxicity and antimicrobial activity of Acticoat Burn Dressing for management of microbial contamination in cultured skin substitutes grafted to athymic mice.

Cultured skin substitutes (CSS) have become a useful adjunctive treatment for closure of burn wounds, but CSS are avascular and remain susceptible to microbial destruction longer than split-thickness skin grafts. Irrigation of CSS grafted to burn wounds with a topical antimicrobial solution (TAS) has been shown to promote engraftment of CSS, but TAS usage has potential limitations. Acticoat Burn Dressing (Acticoat; Westaim Biomedical, Exeter, NH) is a silver-coated barrier dressing reported to exhibit antimicrobial activity and to reduce infection in partial-thickness and full-thickness wounds. This study evaluated the cytotoxicity of Acticoat with CSS and the efficacy of Acticoat for the management of microbial contamination in CSS grafted to full-thickness wounds in athymic mice. The cytotoxicity of Acticoat was assessed in preliminary studies after 1 week of exposure to CSS during in vitro maturation or healing on wounds in athymic mice. Histologies were analyzed and cellular viability in the CSS was determined by MTT conversion on days 0, 1, and 7 of Acticoat exposure. At 1, 2, 3, and 4 weeks after grafting, wounds were traced, and areas of healing CSS were calculated by image analysis. At 4 weeks, wound biopsies were evaluated and scored for engraftment of human cells. In a subsequent study, wounds were inoculated with strain SBI-N of Pseudomonas aeruginosa at 1 x 10(5) cfu/wound before the application of CSS or inoculated onto the surface of Acticoat. At 4 weeks, swab cultures were collected from the surface of CSS and scored for the presence of SBI-N. Statistical significance was accepted at the 95% confidence level (P <.05). The data show that exposure in vitro of CSS to Acticoat was cytotoxic within 1 day, but 1 week of exposure in vivo did not injure CSS or inhibit wound healing. Contaminated wounds treated with Acticoat healed similarly to control treatments, with comparable rates of engraftment, and detection of SBI-N on the surface of only one graft. No SBI-N was detected on CSS after inoculation onto the surface of Acticoat. These results suggest that Acticoat may be suitable as a protective dressing to reduce environmental contamination of CSS, if used in conjunction with additional antimicrobials to control organisms present in the wound.

Determination of Optimal Amikacin Dosing Regimens for Pediatric Patients With Burn Wound Sepsis.

This study aimed to develop optimal amikacin dosing regimens for the empirical treatment of Gram-negative bacterial sepsis in pediatric patients with burn injuries. A pharmacodynamic (PD) target in which the peak concentration (Cmax) is ≥8 times the minimum inhibitory concentration (MIC) (Cmax/MIC ≥ 8) is reflective of optimal bactericidal activity and has been used to predict clinical outcomes. Population pharmacokinetic modeling was performed in NONMEM 7.2 for pediatric patients with and without burn injuries. Amikacin pharmacokinetic parameters were compared between the two groups and multiple dosing regimens were simulated using MATLAB to achieve the PD target in ≥90% of patients with burn injuries. The pharmacokinetic analysis included 282 amikacin concentrations from 70 pediatric patients with burn injuries and 99 concentrations from 32 pediatric patients without burns. A one-compartment model with first-order elimination described amikacin pharmacokinetics well for both groups. Clearance (CL) was significantly higher in patients with burn injuries than in patients without (7.22 vs 5.36 L/h, P < .001). The volume of distribution (V) was also significantly increased in patients with burn injuries (22.7 vs 18.7 L, P < .01). Weight significantly influenced amikacin CL (P < .001) and V (P < .001) for both groups. Model-based simulations showed that a higher amikacin dose (≥25 mg/kg) achieved a Cmax/MIC ≥8 in ≥90% of patients with assumed infections of organisms with an MIC = 8 mg/L. Amikacin pharmacokinetics are altered in patients with burn injuries, including a significant increase in CL and V. In simulations, increased doses (≥25 mg/kg) led to improved PD target attainment rates. Further clinical evaluation of this proposed dosing regimen is warranted to assess clinical and microbiological outcomes in pediatric patients with burn wound sepsis.

Rapid monitoring by quantitative polymerase chain reaction for pathogenic Aspergillus during carpet removal from a hospital.

Monitoring for pathogenic Aspergillus species using a rapid, highly sensitive, quantitative polymerase chain reaction technique during carpet removal in a burn unit provided data that allowed patients to be safely returned to the refloored area sooner than if only conventional culture monitoring had been used.

Investigation of single-use versus reusable infectious waste containers as potential sources of microbial contamination.

BACKGROUND: Laws require that infectious waste be segregated from noninfectious waste. Companies certified to dispose of infectious waste offer both reusable and single-use containers. The focus of this study was to determine if there would be a microbiologic advantage to the use of one type of container over another in a burn hospital. METHODS: Monthly swab cultures were taken from the tops of >250 infectious waste containers during 2 years. Bacteria and fungi were identified. In a substudy swab cultures were taken from an area of reusable tops before and after cleaning to evaluate the efficacy of cleaning on both the number and type of microbes present. Infection rates for acute patients were compared before and after control measures were instituted to decrease microbial transfer from infectious waste containers to patients. RESULTS: Cultures taken from reusable boxes when received from the container company showed that >99% were contaminated with bacteria or fungi; most were normal environmental or skin flora, but some cultures showed microorganisms that can be potentially harmful to patients with compromised immunity. Wiping the lids with a phenolic disinfectant decreased both the total microbial load (P <.001) and the variety of microbes present (P <.001). In contrast, only 10% of the incoming single-use boxes showed any contamination. Infection rates dropped from 5.8 to 3.2 per 100 burn patients (P <.05) after the institution of cleaning and other changes made to decrease the possibility of microbial transfer from the infectious waste boxes to the patients. CONCLUSIONS: Upon delivery, significantly fewer single-use infectious waste boxes were contaminated than reusable ones (P <.001). Extra infection control measures were needed when reusable infectious waste boxes were used in areas housing patients with compromised immunity. Facilities need be aware of the possible contamination of reusable infectious waste containers with microorganisms capable of causing nosocomial infections in patients who are compromised.

Basic microbiologic and infection control information to reduce the potential transmission of pathogens to patients via computer hardware.

Computer technology from the management of individual patient medical records to the tracking of epidemiologic trends has become an essential part of all aspects of modern medicine. Consequently, computers, including bedside components, point-of-care testing equipment, and handheld computer devices, are increasingly present in patients' rooms. Recent articles have indicated that computer hardware, just as other medical equipment, may act as a reservoir for microorganisms and contribute to the transfer of pathogens to patients. This article presents basic microbiological concepts relative to infection, reviews the present literature concerning possible links between computer contamination and nosocomial colonizations and infections, discusses basic principles for the control of contamination, and provides guidelines for reducing the risk of transfer of microorganisms to susceptible patient populations.

Effect of antibiotics on polymorphonuclear neutrophil apoptosis.

STUDY OBJECTIVE: To evaluate the effects of various antibiotics-direct and indirect as a result of bacterial killing-on polymorphonuclear neutrophil (PMN) apoptosis. DESIGN: In vitro analysis. SETTING: Research laboratory. INTERVENTION: Whole blood collected from healthy human subjects was incubated with and without Klebsiella pneumoniae (1.0 x 10(5) colony-forming units [cfu]/ml) plus ceftazidime 50 microg/ml, gentamicin, ciprofloxacin, trovafloxacin, tetracycline, doxycycline, erythromycin, azithromycin (each 5 microg/ml), or lipopolysaccharide 10 microg/ml. After staining with fluorescein-conjugated annexin V, red blood cells were lysed, and the remaining white blood cells were assessed by flow cytometry with gating on PMNs. MEASUREMENTS AND MAIN RESULTS: In the absence of K. pneumoniae infection, antibiotic exposure directly decreased PMN apoptosis by 17.8% (range -25.0% to -13.9%, p=0.008) compared with untreated cells. In the presence of K. pneumoniae, all antibiotic treatments, even those with poor in vitro activity for the bacterial isolate, decreased PMN apoptosis by 26.2% (range -38.0% to -17.8%, p<0.001) compared with untreated control cells and by 36.6% compared with untreated (no antibiotic) K. pneumoniae-stimulated cells (range -46.2% to -28.0%, p<0.001). CONCLUSIONS: All tested antibiotics in clinically relevant concentrations resulted in modest yet consistent decreases in PMN apoptosis. The magnitude of this change increased slightly in the presence of K. pneumoniae infection. In vivo studies are needed to determine whether antibiotic-associated prolongation of PMN survival improves host response to infection.

Procalcitonin in pediatric burn patients: an early indicator of sepsis?

To determine whether changes in procalcitonin (PCT) could be used to predict the onset of sepsis, daily PCT levels were monitored in 20 burned children. Analysis indicated a PCT rise of 5 ng/ml or greater as the best indication of sepsis. We compared the surgeons' determination of sepsis, which was based on changes in platelet count, C-reactive protein (CRP), and other clinical manifestations, with the prediction of sepsis from PCT. There were 26 septic episodes and 36 nonseptic episodes in the 20 patients. PCT results were classified as to true positives, false positives, true negatives, and false negatives. As an indicator of sepsis, the PCT assay had a sensitivity of 42%, a specificity of 67%, and an efficiency of 57%. Even when the assay correctly identified sepsis, the determination was made an average of 0.8 days after the surgeon had already made the diagnosis based on CRP and/or platelet count. We conclude that PCT is not as effective as CRP and/or platelet count in the early detection of sepsis in burned children.

Differential effects of two different routes of immunization on protection against gram-negative sepsis by a detoxified Escherichia coli J5 lipopolysaccharide group B meningococcal outer membrane protein complex vaccine in a burned mouse model.

Gram-negative sepsis causes morbidity and mortality in burned patients. To determine whether immunization with core endotoxin (lipopolysaccharide) via one of two routes could protect burned mice from septic death, mice were immunized either three times subcutaneously (SC) or one time intramuscularly (IM) then two times intraperitoneally (IP) with a core-lipopolysaccharide vaccine. Control mice were immunized with either saline or an irrelevant antigen. Postimmunization, mice were immunocompromised with a 15% TBSA flame burn and challenged subeschar with Klebsiella pneumoniae or Escherichia coli. Vaccine immunization improved the survival of both E. coli- and K. pneumoniae-challenged mice when given SC but not when given IM, IP. Postimmunization, total immunoglobulin titers were elevated over preimmune titers, but titers in IM, IP-immunized mice were higher than those in SC-immunized mice. Both isotyping and flow cytometry studies indicated that sera from mice immunized via IM, IP opsonized better than sera from mice immunized via SC. Hence, this vaccine provided route-specific protection of burned mice against gram-negative sepsis; its mechanism of action was not solely dependent upon increased immunoglobulin titers or phagocytosis.

Trends in bacterial wound isolates and antimicrobial susceptibility in a pediatric burn hospital.

The purpose of this retrospective study was to collate data dealing with organisms cultured from the burn patients and evaluate trends in antimicrobial susceptibility. All cultures collected from each acute admission patient between 2004 and 2011 in the 30-bed pediatric burn hospital were evaluated for their annual frequency and antimicrobial susceptibility. Duplicate cultures were excluded. Staphylococcus aureus was isolated most frequently (25% of total isolates; range, 69-408 isolates/yr), followed by Pseudomonas aeruginosa (13%; range, 40-202 isolates/yr), coagulase-negative staphylococci (9%; range, 2-188 isolates/yr), Enterobacter cloacae (8%; range, 22-128 isolates/yr), and Escherichia coli (6%; range, 19-91 isolates/yr). This rank order remained relatively consistent during the period of study. The emergence of methicillin-resistant S. aureus increased from 20% in 2004 to about 45% in 2009 to 2011. Susceptibility to vancomycin was still 100%. In comparing periods 2004 to 2007 and 2008 to 2011, P. aeruginosa showed increased susceptibility to cefepime (from 76% to 84%) and the aminoglycosides (from 68% to 81%), whereas susceptibility to piperacillin-tazobactam remained high (from 91% to 93%). E. cloacae demonstrated 90 to 100% susceptibility to aminoglycosides, cefepime, and imipenem. E. coli showed an increased rate of resistance to ceftazidime but was still susceptible to imipenem and amikacin. S. aureus and P. aeruginosa continue to be the most prevalent organisms cultured from our pediatric burn population. Almost half of the staphylococcal isolates were methicillin-resistant S. aureus. Despite widespread use of piperacillin-tazobactam, P. aeruginosa susceptibility remained high. Several classes of antimicrobials continued to demonstrate good to excellent activity against the majority of organisms cultured from the burn patients.

Amish burn ointment and burdock leaf dressings: assessments of antimicrobial and cytotoxic activities.

Amish burn wound ointment (ABO) contains honey, lanolin, oils, glycerin, bees wax, and other natural additives. Although there are many anecdotal reports that this ointment covered with a burdock leaf (BL) dressing promotes burn wound healing, little scientific testing of this treatment has occurred. The goal of this study was to evaluate in vitro some of the components of this treatment modality for antimicrobial and cytotoxic activities. The ABO was tested for sterility using standard microbiological techniques. Because of the semisolid, lipid-based nature of the salve, the at-use product could not be tested in bioassays. Samples of BL and the dry ingredients (DI) used in the ointment were provided by the Amish vendor. Aqueous extracts of the DI and of the BL were prepared and freeze dried. The freeze-dried extracts were reconstituted, filtered, and tested separately on keratinocyte and fibroblast cell cultures for cytotoxicity (growth inhibition assay) and against a panel of susceptible and resistant microbes for antimicrobial activity (Nathan's agar-well diffusion assay) in a series of concentrations (% wt/vol). Neither DI nor BL extracts demonstrated antimicrobial activity against any of organisms tested. The DI extract inhibited growth of both keratinocytes and fibroblasts at the 0.1% concentration. The 0.1 and 0.03% concentrations of the BL extract were cytotoxic to both keratinocytes and fibroblasts. Although tests for microbial growth from the at-use preparation of the ABO were negative, extracts of the DI and BL did not demonstrate any antimicrobial activity. Additionally, both extracts inhibited the growth of skin cells in vitro at higher concentrations. These results suggest caution in the use of ABO and BL dressings if there is more than a minimal risk of complications from the burn injury.

A performance improvement initiative to determine the impact of increasing the time interval between changing centrally placed intravascular catheters.

Existing practice guidelines designed to minimize invasive catheter infections and insertion-related complications in general intensive care unit patients are difficult to apply to the burn population. Burn-specific guidelines for optimal frequency for catheter exchange do not exist, and great variation exists among institutions. Previously, the authors' practice was to follow a new site insertion at 48 hours by an exchange over a guidewire, which was followed 48 hours later by a second guidewire exchange (48h group). As a performance improvement initiative, the authors attempted to determine whether there would be any advantage or disadvantage to extending these intervals to 72 hours (72h). All patients with centrally placed intravascular catheters from October 2007 to August 2008 were included in the 48h group, and all patients with catheters placed from September 2008 to December 2009 comprised the 72h group. Catheter infection rates were determined using the National Healthcare Safety Network definition for central line-associated bloodstream infections (CLABSIs) and calculated as CLABSIs/1000 catheter days. The two groups were not significantly different for age, sex, burn etiology, total burn size, or percent third-degree burn. There were 3.1 CLABSIs/1000 catheter days for the 48h group and 2.8 CLABSIs/1000 catheter days for the 72h group (NS). The authors conclude that increasing the central catheter change interval from 48 to 72 hours did not result in any increase in their CLABSI rate. Implementation of this change in practice is expected to decrease supply costs by $28,000 annually in addition to reducing clinical support services needed to perform these procedures.

A survey of invasive catheter practices in U.S. burn centers.

Burn-specific guidelines for optimal catheter rotation, catheter type, insertion methods, and catheter site care do not exist, and practices vary widely from one burn unit to another. The purpose of this study was to define current practices and identify areas of practice variation for future clinical investigation. An online survey was sent to the directors of 123 U.S. burn centers. The survey consisted of 23 questions related to specific practices in placement and maintenance of central venous catheters (CVCs), arterial catheters, and peripherally inserted central catheters (PICCs). The overall response rate was 36%; response rate from verified centers was 52%. Geographic representation was wide. CVC and arterial catheter replacement varied from every 3 days (24% of sites) to only for overt infection (24% of sites); 23% of sites did not use the femoral position for CVC placement. Nearly 60% of units used some kind of antiseptic catheter. Physicians inserted the majority of catheters, and 22% of sites used nonphysicians for at least some insertions. Ultrasound was routinely used by less than 50% of units. A wide variety of post-insertion dressing protocols were followed. PICCs were used in some critically injured patients in 37% of units; the majority of these users did not rotate PICCs. Thus, it can be surmised that wide practice variation exists among burn centers with regard to insertion and maintenance of invasive catheters. Areas with particular variability that would be appropriate targets of clinical investigation are line rotation protocols, catheter site care protocols, and use of PICCs in acute burns.

Pharmacokinetics of colistin in an adolescent boy with extensive burn injury.

Multidrug resistance in Gram-negative bacteria has led to a resurgence in colistin use. No pharmacokinetic data exist for burn patients. A 17-year-old boy suffered a 71% TBSA full-thickness burn with deep necrosis and compartment syndrome. He developed multidrug-resistant Acinetobacter baumannii burn wound sepsis/septic shock with acute renal failure requiring dialysis. The organism was resistant to all tested antibiotics except colistin. He received colistin 2.5 mg/kg every 24 hours. Peak and trough serum concentrations, area under the concentration-time curve, and elimination half-lives of colistin were 3.6 ± 1.0 µg/ml, 0.9 ± 0.5 µg/ml, 47.1 ± 14.4 mg · hr/L, and 12.3 ± 9.4 hours (mean ± SD), respectively. Serum levels were at or above the minimum inhibitory concentration for >90% of therapy. Nevertheless, salvage therapy with colistin proved futile as the patient developed acidosis, coagulopathy, and was vasopressor-dependent without any wound healing. He died on hospital day 52. Microbiologically, the serum levels of colistin were seemingly adequate, as repeat cultures were negative. Given the peak and trough levels of colistin relative to the minimum inhibitory concentration for the organism (0.5 µg/ml), it would seem that the dosage of 2.5 mg/kg administered every 24 hours for this patient on dialysis was appropriate. Patients on dialysis infected with an organism possessing a higher inhibitory concentration (≥1 µg/ml) should probably receive the same dosage every 12 hours to avoid subtherapeutic concentrations. Large-scale study of the pharmacokinetics of colistin in patients with burn injury is urgently needed.

Antibiotic resistance in clinical isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus does not impact sensitivity to human beta defensin 4.

Antibiotic usage is essential for infection control but hastens emergence of antibiotic resistant microbes. In particular, Acinetobacter baumannii is an important pathogen because of its heightened ability to acquire drug resistance. The need for novel antibacterial agents led us to evaluate the sensitivity of drug-resistant bacteria to the antimicrobial activity of human beta defensin 4 (HBD-4). Clinical isolates of A. baumannii (N=14), Pseudomonas aeruginosa (N=15), and Staphylococcus aureus (N=20), including 10 methicillin-resistant (MRSA) isolates, were examined. All bacterial strains were susceptible to HBD-4 antimicrobial activity, with no correlation between antibiotic resistance and HBD-4 sensitivity. The results demonstrate that antibiotic resistant microorganisms, including MRSA, can be inhibited by HBD-4, which may represent an effective therapeutic agent for infections involving drug-resistant microorganisms.

Differential immunological phenotypes are exhibited after scald and flame burns.

A dysfunctional immune system is known to be part of the pathophysiology after burn trauma. However, reports that support this have used a variety of methods, with numerous variables, to induce thermal injury. We hypothesized that, all other parameters being equal, an injury infliction by a scald would yield different immunological responses than one inflicted by a flame. Here, we demonstrated that both burn methods produced a full-thickness burn, yet there was more of an increase in subdermal temperature, hematocrit, mortality, and serum IL-6 concentrations associated with the scald burn. On postinjury day 1, the scald-burned mice showed diminished lymphocyte numbers, interferon gamma production, and lymphocyte T-bet expression as compared with sham- and flame-burned mice. On postburn day 8, spleens from both sets of thermally injured animals showed an increase in proinflammatory myeloid cells as compared with sham-burned mice. Furthermore, the T-cell numbers, T-bet expression, and phenotype were changed such that interferon gamma production was higher in scald-burned mice than in sham- and flame-burned mice. Altogether, the data show that differential immunological phenotypes were observed depending on the thermal injury method used.

Are topical antimicrobials effective against bacteria that are highly resistant to systemic antibiotics?

An increasing number of bacteria are resistant to multiple systemic antibiotics. The purpose of this study was to determine if topical antimicrobials are still effective against multi-drug resistant organisms (MDROs). MDROs, including Acinetobacter, Pseudomonas, Klebsiella, Staphylococcus, and Enterococcus, were collected from four burn hospitals. The sensitivity of 47 MDROs to 11 commonly used topical agents (mafenide acetate, nystatin, mafenide + nystatin, silver nitrate, Dakin's, polymyxin B, neomycin, polymyxin + neomycin, silver sulfadiazine, bacitracin, silver sulfadiazine + bacitracin) was tested using the agar well diffusion assay and compared with the sensitivity of 27 non-MDROs of similar genera. Overall 88% of the tests of the non-MDROs showed susceptibility to the topicals compared with 80% for the MDROs (P < .05). Specific findings included: all of the gram-positive non-MDROs were sensitive to bacitracin compared with only 67% of the MDROs (P < .05); 74% of the non-MDROs were sensitive to neomycin vs 26% of the MDROs (P < .01). Even for the susceptible isolates, the zones of inhibition were smaller for the MDROs than for the non-MDROs (P < .002), indicating decreased susceptibility of the MDROs. Specifically, while the MDRO Acinetobacter were sensitive to most of the topicals, the zones of inhibition for silvadene, silvadene + bacitracin, neomycin, and neomycin + polymyxin were significantly smaller (P < .001) for the Acinetobacter MDROs than the non-MDROs. Although many topicals are still effective against some MDROs, MDROs are more resistant to topicals than are non-MDROs. Some treatment assumptions based historically on the efficacy of topical antimicrobial agents against non-MDROs need to be re-evaluated for MDROs.