A Clinical Scoring System and Impact of Athymic Nude Mouse Age on Corynebacterium bovis Clinical Disease.

Corynebacterium bovis infection in biomedical research is synonymous with skin hyperkeratosis of athymic nude mice. This clinical sign can be obvious and is the namesake for 'scaly skin disease.' Other clinical signs that accompany scaly skin, including early presentation, duration, and rate of resolution, are less well known. The goal of this study was to characterize the clinical signs of C. bovis infection in nude mice under experimental conditions and develop a quantifiable scoring system. For the development, prospective trial, and application of this clinical scoring system, 93 naïve Hsd:Athymic Nude mice were used, of which 81 were exposed to soiled bedding from clinically ill C. bovis-infected NSG mice. The emergence of clinical signs was monitored and scored daily for 14 d. We identified 3 categories of clinical signs including skin hyperemia, skin hyperkeratosis, and surrogate indicators of overall health. Each of these defined categories appeared consistently and progressed and regressed temporally. We subsequently used this scoring system to determine if the age of Hsd:Athymic Nude mice (6 compared with 10 wk) at time of infection affects clinical severity. Our findings demonstrate that 6-wk-old mice demonstrate more severe clinical signs. Ten-week-old mice showed less skin hyperemia and no skin hyperkeratosis and were less affected by the infection based on surrogates of overall health. Here we show the utility of this novel scoring system and the impact of nude mouse age at the time of infection on C. bovis clinical disease.

Antibiotic Treatment of Corynebacterium bovis-associated Clinical Disease in NSG Mice.

Depending on the strain of immunodeficient mice, Corynebacterium bovis infection can be asymptomatic or cause transient or prolonged skin disease. C. bovis infection of NOD. Cg- Prkdcscid Il2rgtm1Wjl /SzJ (NSG) mice results in clinical skin disease that progresses in severity. Amoxicillin metaphylaxic and prophylaxic therapy prevents transmission and infection of mice after exposure to C. bovis and inhibits the growth of C. bovis isolates at therapeutic doses that are clinically achievable in mice. Amoxicillin is not efficacious for treatment of transient clinical skin disease in athymic nude mice, but the efficacy of amoxicillin treatment has not previously been characterized in C. bovis -infected NSG mice. In the current study, NSG mice were treated with amoxicillin beginning at 5 wk after exposure to C. bovis, at which time they had well-established clinical signs of disease. Clinical signs were scored to assess disease progression, regression, and reappearance. Our results showed that amoxicillin treatment for 3 or 6 wk reduced the clinical scores of NSG mice with C. bovis -associated clinical disease. In addition, withdrawal of treatment led to the recurrence of clinical signs. Collectively, our data suggest that amoxicillin treatment is effective in alleviating the clinical signs associated with C. bovis infection for the duration of treatment in NSG mice. Clinical intervention with antibiotics for C. bovis -infected NSG mice can be an option for management of C. bovis -related clinical disease either before or during facility-wide remediation efforts.

Pyochelin biotransformation by Staphylococcus aureus shapes bacterial competition with Pseudomonas aeruginosa in polymicrobial infections.

Pseudomonas aeruginosa and Staphylococcus aureus are among the most frequently isolated bacterial species from polymicrobial infections of patients with cystic fibrosis and chronic wounds. We apply mass spectrometry guided interaction studies to determine how chemical interaction shapes the fitness and community structure during co-infection of these two pathogens. We demonstrate that S. aureus is equipped with an elegant mechanism to inactivate pyochelin via the yet uncharacterized methyltransferase Spm (staphylococcal pyochelin methyltransferase). Methylation of pyochelin abolishes the siderophore activity of pyochelin and significantly lowers pyochelin-mediated intracellular reactive oxygen species (ROS) production in S. aureus. In a murine wound co-infection model, an S. aureus mutant unable to methylate pyochelin shows significantly lower fitness compared with its parental strain. Thus, Spm-mediated pyochelin methylation is a mechanism to increase S. aureus survival during in vivo competition with P. aeruginosa.

Effects of Extended Cage Component Sanitation Interval on the Microenvironment, Health, and Gastrointestinal Microbiome of Rats (Rattus norvegicus).

Washing and sanitizing rodent cage components requires costly equipment, significant personnel effort, and use of natural resources. The benchmark frequency for sanitation of individually ventilated caging (IVC) has traditionally been every 2 wk. In this study, we investigated the effects of extending this interval on the cage microenvironment, basic markers of health, and the gastrointestinal microbiota of rats. We compared our institutional standard of changing the sanitation interval for rat cage lids, box feeders, and enrichment devices from every 4 wk to an interval of 12 wk. The cage bottom and bedding continued to be changed every 2 wk for both groups. We hypothesized that we would find no significant difference between our current practice of 4 wks and continuous use for 12 wk. Our data showed that intracage ammonia levels remained below 5 ppm for most cages in both groups, with the exception of cages that experienced a cage flood. We found no significant difference between groups in bacterial colony forming units (CFU) on cage components. We used 3 novel methods of assessing cleanliness of enrichment devices and found no significant effect of continuous use for 12 wk on the number of CFU. In addition, we found no significant differences between groups for animal weight, routine blood work, or fecal and cecal microbiomes. These data indicate that a sanitation interval of up to 12 wk for components of rat IVC caging has no significant effects on the microenvironment or health of rats. Using the longer interval will improve efficiency, reduce the use of natural resources, and decrease costs while maintaining high-quality animal care.

Effect of Antimicrobial Prophylaxis on Corynebacterium bovis Infection and the Skin Microbiome of Immunodeficient Mice.

Corynebacterium bovis is an opportunistic pathogen of the skin of immunodeficient mice and is sensitive to oral antibiotics that reach therapeutic blood concentrations. However, prophylactic antibiotics are considered to be ineffective at preventing C. bovis infection. In addition, the effect of C. bovis on the skin microbiome (SM) of common immunodeficient mouse strains has yet to be characterized. Consequently, we evaluated whether oral prophylactic antibiotics prevent C. bovis infection after inoculation. An infectious dose of C. bovis was applied to the skin of Hsd:Athymic Nude (nude) and NOD. Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Mice were then housed individually and assigned randomly to receive either untreated drinking water (Cb+Abx-group) or prophylactic amoxicillin-clavulanic acid in the drinking water (0.375 mg/mL) for 14 d (Cb+Abx+group). A third treatment group of each mouse strain was uninoculated and untreated (Cb-Abx-group). Mice from all groups were serially sampled by using dermal swabs to monitor C. bovis infection via quantitative real-time PCR and the SM via 16S rRNA sequence analysis. Fourteen days of prophylactic antibiotics prevented the perpetuation of C. bovis skin infection in both strains. Only the combination of C. bovis inoculation and oral antibiotics (Cb+Abx+) significantly affected the SM of NSG mice at day 14; this effect resolved by the end of the study (day 70). In mice that did not receive antibiotics, C. bovis significantly altered the SM of nude mice but not NSG mice at days 14 and 70. These findings demonstrate the potential benefit of prophylactic antibiotics for prevention of C. bovis infection. However, indirect effect of antibiotics on commensal bacteria and potential effects on xenograft models must be considered.

Synthesis, characterization and evaluation of azobenzene nanogels for their antibacterial properties in adhesive dentistry.

The presence of cariogenic bacteria within the prepared tooth cavity at the adhesive resin-dentin interface is detrimental to the long-term stability and function of composite restorations. Here, we report the synthesis and incorporation of methacrylated azobenzene nanogels within bisphenol A-glycidyl methacrylate/hydroxyethyl methacrylate/ethanol (B/H/E) adhesive resins and evaluate their ability to reduce the bacterial invasion of cariogenic Streptococcus mutans biofilms while preserving the mechanical strength and structural integrity of the critical interfacial connection between the restoration and the tooth. The azobenzene nanogel, with a hydrodynamic radius of < 2 nm and a molecular weight of 12,000 Da, was polymerized within B/H/E adhesive formulations at concentrations of 0.5 wt.%, 1.5 wt.%, and 2.5 wt.%. While the double-bond conversion, cytocompatibility, water solubility, and sorption of the adhesive networks were comparable, azobenzene nanogel networks showed improved hydrophobicity with a ≥ 25° increase in water contact angle. The polymerized adhesive surfaces formulated with azobenzene nanogels showed a 66% reduction in bacterial biofilms relative to the control while maintaining the mechanical properties and micro-tensile bond strength of the adhesive networks. The increased hydrophobicity and antibacterial activity are promising indicators that azobenzene nanogel additives have the potential to increase the durability and longevity of adhesive resins.

A Clinical Scoring Systems for the Evaluation of Corynebacterium bovis -associated Disease in NSG Mice.

Clinical signs of Corynebacterium bovis infections are well-known in athymic nude mice. However, C. bovis can also infect and cause clinical signs in many hirsute, immunocompromised mouse strains such as NSG (NOD. Cg-Prkdcscid Il2rgtm1Wgl/SzJ). Typically, the clinical assessment of C. bovis-infected mice begins when overt clinical signs are initially observed and thus the early course of infection has not been thoroughly described. The goal of this study was to characterize the clinical progression of C. bovis infection in NSG mice under experimental conditions and develop a quantifiable clinical scoring system. For the development and application of this clinical scoring system, 54 naïve NSG mice were exposed to soiled bedding from clinically ill C. bovis-infected NSG mice and the emergence of clinical signs was monitored and scored weekly for 8 wk. Overall, we identified 6 benchmark changes associated with C. bovis clinical infection. Four changes were the appearance of the eyes, ears, hair coat, and posture. Two behavioral changes were increased grooming activity and rapid head shaking. All clinical signs appeared consistently and progressed temporally with increasing clinical severity. Characterization of clinical signs and scoring of clinical disease will aid veterinarians in the assessment of C. bovis-infected NSG mice and may help in the evaluation of current and future clinical interventions used to prevent or treat C. bovis-infected immunodeficient mice.

Acrylated Hydroxyazobenzene Copolymers in Composite-Resin Matrix Inhibits Streptococcus mutans Biofilms In Vitro.

Purpose: The purpose of this study was to evaluate the effect of acrylated hydroxyazobenzene (AHA) copolymers in a composite-resin matrix on Streptococcus mutans (SM) biofilms. Methods: The AHA was synthesized and polymerized within a bisphenol A-glycidyl methacrylate and triethylene glycol dimethacrylate (bisGMA:TEGDMA) matrix while bisGMA:TEGDMA discs served as controls. The cytotoxicity of AHA was determined using a cell viability assay. Sucrose-dependent SM biofilms were grown on the AHA and control substrates. At 24 hours and after mechanical toothbrushing (equivalent to six months), the number of live SM was quantified on the substrates and in the surrounding media. Microscopic images of the substrates were captured after live-dead staining. Results: The AHA substrates were as biocompatible as bisGMA: TEGDMA substrates. The microscopic images and quantification demonstrated no live SM on the AHA substrates and in the surrounding media as compared to the controls. The inhibitory efficacy of AHA substrates on SM biofilm was intact even after mechanical toothbrushing. Conclusions: Acrylated hydroxyazobenzene in a composite-resin matrix completely inhibits SM proliferation growth and demonstrates a zone of SM inhibition. The antibacterial propertyof AHA could be harnessed for caries prevention in high caries-risk children by incorporating AHA into the restorative and sealant materials.

The Bactericidal Tandem Drug, AB569: How to Eradicate Antibiotic-Resistant Biofilm Pseudomonas aeruginosa in Multiple Disease Settings Including Cystic Fibrosis, Burns/Wounds and Urinary Tract Infections.

The life-threatening pandemic concerning multi-drug resistant (MDR) bacteria is an evolving problem involving increased hospitalizations, billions of dollars in medical costs and a remarkably high number of deaths. Bacterial pathogens have demonstrated the capacity for spontaneous or acquired antibiotic resistance and there is virtually no pool of organisms that have not evolved such potentially clinically catastrophic properties. Although many diseases are linked to such organisms, three include cystic fibrosis (CF), burn/blast wounds and urinary tract infections (UTIs), respectively. Thus, there is a critical need to develop novel, effective antimicrobials for the prevention and treatment of such problematic infections. One of the most formidable, naturally MDR bacterial pathogens is Pseudomonas aeruginosa (PA) that is particularly susceptible to nitric oxide (NO), a component of our innate immune response. This susceptibility sets the translational stage for the use of NO-based therapeutics during the aforementioned human infections. First, we discuss how such NO therapeutics may be able to target problematic infections in each of the aforementioned infectious scenarios. Second, we describe a recent discovery based on years of foundational information, a novel drug known as AB569. AB569 is capable of forming a "time release" of NO from S-nitrosothiols (RSNO). AB569, a bactericidal tandem consisting of acidified NaNO2 (A-NO2 -) and Na2-EDTA, is capable of killing all pathogens that are associated with the aforementioned disorders. Third, we described each disease state in brief, the known or predicted effects of AB569 on the viability of PA, its potential toxicity and highly remote possibility for resistance to develop. Finally, we conclude that AB569 can be a viable alternative or addition to conventional antibiotic regimens to treat such highly problematic MDR bacterial infections for civilian and military populations, as well as the economical burden that such organisms pose.

Bacterial reduction effect of four different dental lasers on titanium surfaces in vitro.

Compare the effectiveness of selected dental lasers for decontamination of machined titanium surfaces in vitro. Seventy-two sterile machined surface titanium discs were individually inoculated with strains of Streptococcus mutans (Sm), Streptococcus oralis (So), Aggregatibacter actinomycetemcomitans (Aa), or all three bacteria together (MIX) at 34.0° C, 20.8% O2 and 5% CO2 for 12 h. After incubation, the discs were divided into six groups: 1) no treatment, 2) 0.12% chlorhexidine gluconate (CHX), and 3) 10,600 CO2, 4) 810 nm diode, 5) 2780 nm Er,Cr:YSGG, 6) 1064 nm Nd:YAG laser groups. After treatment, any remaining viable bacteria were liberated from the discs via sonication, transferred onto brain heart infusion (BHI) agar plates for culturing, and colony-forming units (CFUs) were recorded. Statistical analysis was performed. There were statistically significantly differences (SSD) (p < 0.01) in bacterial reduction of discs individually inoculated with Aa between the Er,Cr:YSGG and Nd:YAG lasers. There was also a SSD (p < 0.01) lower effect with the MIX with the Er,Cr:YSGG compared with all other modalities. Bacterial reduction with the CO2 was better (p < 0.001) than treatment with CHX or the Er,Cr:YSGG laser on killing of So. Although all modalities of treatment showed a mean of 98% or greater viable bacterial reduction, the most consistent bacterial reduction of all titanium discs was with the Nd:YAG laser (100%).

Changing the Wound: Covalent Immobilization of the Epidermal Growth Factor.

Re-epithelialization of wounds is a critical element of wound closure. Growth factors have been used in combination with conventional wound management to promote closure, but the method of delivery has been limited to the topical application of ointment formulations. Cytoactive factors delivered in this way have short resident times in wounds and have met with limited success. Here, we demonstrate that methods used to covalently immobilize proteins on synthetic materials can be extended to immobilize cytoactive factors such as the epidermal growth factor (EGF) onto the wound beds of genetically diabetic mice that exhibit impaired healing. Full-thickness splinted excisional wounds were created in diabetic (db/db) mice with a well-defined silicone splint to limit wound contracture. Wound surfaces were treated with a reducing agent to expose sulfhydryl groups and subsequently treated with EGF modified with a heterobifunctional crosslinker. This allowed for the covalent immobilization of the EGF to the wound surface. The conjugation chemistry was validated in vitro and in vivo. In a separate group of mice, wounds were topically treated twice daily with soluble EGF. The mice were evaluated over 11 days for wound closure. This covalent immobilization strategy resulted in EGF being retained on the wound surface for 2 days and significantly increased epithelial wound closure by 20% compared to wounds treated with topical EGF or topical vehicle. Covalent immobilization was not only therapeutically effective but also delivered a markedly reduced load of growth factor to the wound surface compared to topical application (when only 180 ng of EGF was immobilized onto the wound surface in comparison with 7200 ng of topically applied EGF over a period of 11 days). No adverse effects were observed in treated wounds. Results obtained provide proof of concept for the effectiveness of covalent immobilization in the treatment of dysregulated wounds. The covalent immobilization of cytoactive factors represents a potentially transformative approach to the management of difficult chronic wounds.

Antimicrobial Susceptibility of Corynebacterium bovis Isolates from Immunodeficient Rodents.

Corynebacterium bovis, the causative agent of hyperkeratotic dermatitis in immunodeficient mice, is a significant problem in preclinical oncology research. Infection results in lifelong skin colonization and a decrease in successful engraftment of patient-derived xenograft tumor models. The use of antimicrobial agents for C. bovis is controversial in light of reports of poor efficacy and the possibility of selection for resistant strains. The purpose of this study was to describe the antimicrobial susceptibilities of C. bovis isolates obtained exclusively from immunodeficient rodents in order to aid in antimicrobial dose determination. Between 1995 and 2018, 15 isolates were collected from 11 research institutions across the United States. Antimicrobial susceptibility testing was performed for 24 antimicrobials commonly used against gram-positive bacteria. Our results provide an updated understanding of the susceptibility profiles of rodent C. bovis isolates, indicating little variability between geographically and temporally distant isolates. These results will facilitate appropriate antimicrobial use to prevent and treat C. bovis infections in immunodeficient rodents.

AB569, a non-toxic combination of acidified nitrite and EDTA, is effective at killing the notorious Iraq/Afghanistan combat wound pathogens, multi-drug resistant Acinetobacter baumannii and Acinetobacter spp.

Multi-drug resistant (MDR) Acinetobacter baumannii (Ab) and Acinetobacter spp. present monumental global health challenges. These organisms represent model Gram-negative pathogens with known antibiotic resistance and biofilm-forming properties. Herein, a novel, nontoxic biocide, AB569, consisting of acidified nitrite (A-NO2-) and ethylenediaminetetraacetic acid (EDTA), demonstrated bactericidal activity against all Ab and Acinetobacter spp. strains, respectively. Average fractional inhibitory concentrations (FICs) of 0.25 mM EDTA plus 4 mM A-NO2- were observed across several clinical reference and multiple combat wound isolates from the Iraq/Afghanistan wars. Importantly, toxicity testing on human dermal fibroblasts (HDFa) revealed an upper toxicity limit of 3 mM EDTA plus 64 mM A-NO2-, and thus are in the therapeutic range for effective Ab and Acinetobacter spp. treatment. Following treatment of Ab strain ATCC 19606 with AB569, quantitative PCR analysis of selected genes products to be responsive to AB569 revealed up-regulation of iron regulated genes involved in siderophore production, siderophore biosynthesis non-ribosomal peptide synthetase module (SBNRPSM), and siderophore biosynthesis protein monooxygenase (SBPM) when compared to untreated organisms. Taken together, treating Ab infections with AB569 at inhibitory concentrations reveals the potential clinical application of preventing Ab from gaining an early growth advantage during infection followed by extensive bactericidal activity upon subsequent exposures.

Metaphylactic Antibiotic Treatment to Prevent the Transmission of Corynebacterium bovis to Immunocompromised Mouse Offspring.

Current methods for eradicating Corynebacterium bovis, such as depopulation, embryo transfer, and cesarean rederivation followed by cross fostering, are expensive, complex, and time-consuming. We investigated a novel method to produce immunocompromised offspring free of C. bovis from infected NOD. Cg-PrkdcscidIl2rgtm1Wgl/SzJ (NSG) breeding pairs. Adult NSG mice were infected with C. bovis, paired, and randomly assigned to either a no-antibiotic control group (NAB, n = 8) or a group that received amoxicillin-clavulanic acid (0.375 mg/mL) in their drinking water for a mean duration of 7 wk (AB group, n = 7), spanning the time from pairing of breeders to weaning of litters. The AB group also underwent weekly cage changes for 3 wk after pairing to decrease intracage C. bovis contamination, whereas the NAB mice received bi-weekly cage changes. Antibiotics were withdrawn at the time of weaning. All litters (n = 7) in the AB group were culture- and qPCR-negative for C. bovis and remained negative for the duration of the study, whereas all litters in the NAB group (n = 6) remained C. bovis positive. A single adult from each breeding pair was sampled at weaning and at 5 and 10 wk after weaning to confirm the maintenance of (NAB) or to diagnose the reemergence (AB) of C. bovis infection. By the end of the study, C. bovis infection had returned in 3 of the 7 (43%) tested AB adults. Our data suggest that metaphylactic antibiotic use can decrease viable C. bovis organisms from adult breeder mice and protect offspring from infection. However, using antibiotics with frequent cage changing negatively affected breeding performance. Nevertheless, this technique can be used to produce C. bovis-free NSG offspring from infected adults and may be an option for salvaging infected immunocompromised strains of mice that are not easily replaced.

Early Comfort Care Following Operative Intervention for Traumatic Injury.

BACKGROUND: Several studies have described the population of adult trauma patients who undergo withdrawal of life-sustaining treatments (WLST); however, no study has looked specifically at trauma patients who undergo WLST following surgery. METHODS: This was a retrospective chart review of all trauma patients who underwent surgery at our trauma center between January 1 and December 31, 2017. Demographics were collected along with injury patterns and advance directives. Charts of all patients who died or who were discharged to hospice were analyzed to determine whether WLST occurred. Statistics included Fisher's exact test and Mann-Whitney U test. RESULTS: Three thousand and twenty-five adult trauma patients received care and 1495 (49.4%) had operations. Thirty (2.0%) patients underwent WLST, 15 (50.0%) of whom died in the hospital and 15 (50.0%) of whom were discharged to hospice. Twenty-six (86.7%) patients had a palliative care consult and 12 (40.0%) had prior advance directives. The most common injuries were femur fractures and subdural hematomas. Adjusting for age, white race, and age-adjusted CCI, femur fracture patients had, on average, 8.8 more hours between presentation and surgery (95% CI 2.1-15.4, P = .01) and 39 fewer hours between surgery and WLST (95% CI -107-29, P = .26) than traumatic brain injury patients. DISCUSSION: The short time between surgery and WLST in this cohort of patients may demonstrate that surgery was not aligned with patients' goals of care. A patient-centered approach that includes surgeon-driven palliative care discussions may help avoid nonbeneficial surgery in the last few days of life.

The Overall Poor Specificity of MRCP in the Preoperative Evaluation of the Jaundiced Patient Will Increase the Incidence of Nontherapeutic ERCP.

Laparoscopic cholecystectomy remains one of the most common surgical operations. Common bile duct stones (CBDS) are estimated to be present in 10%-20% of individuals with symptomatic gallstones. Preoperative magnetic resonance cholangiopancreatography (MRCP) and intraoperative cholangiography (IOC) remain the most common methods of evaluation, with subsequent endoscopic retrograde cholangiopancreatography (ERCP) for stone extraction if positive for CBDS. We examined our experience with preoperative MRCP versus IOC for the management of the jaundiced patient with cholelithiasis. This is a retrospective single-institution study that examined all laparoscopic cholecystectomies performed over a 15-month period between 2017 and 2018. Outpatient elective cases were excluded from the analysis. Charts were reviewed for demographics, operative details, and whether an MRCP, IOC, or ERCP was performed. Data were evaluated using a 2-sample t-test. A total of 460 patients underwent laparoscopic cholecystectomy over a 15-month period. Of those, 147 underwent either an MRCP or an IOC for clinical suspicion for CBDS. ERCP after MRCP was nontherapeutic in 11/32 (34%) compared with 2/12 (17%) of patients following IOC. The sensitivity and specificity of MRCP were 91% and 80%, respectively, with a positive predictive value of 66% and a negative predictive value of 96%. The sensitivity and specificity of IOC were 83% and 97%, respectively, with a positive predictive value of 83% and a negative predictive value of 97%. MRCP and IOC have unique advantages and disadvantages. MRCP has greater sensitivity, but poor specificity, resulting in unnecessary ERCPs with associated morbidity and increased costs to the patient.

Into the wild and on to the table: A Western Trauma Association multicenter analysis and comparison of wilderness falls in rock climbers and nonclimbers.

BACKGROUND: Wilderness activities expose outdoor enthusiasts to austere environments with injury potential, including falls from height. The majority of published data on falls while climbing or hiking are from emergency departments. We sought to more accurately describe the injury pattern of wilderness falls that lead to serious injury requiring trauma center evaluation and to further distinguish climbing as a unique pattern of injury. METHODS: Data were collected from 17 centers in 11 states on all wilderness falls (fall from cliff: International Classification of Diseases, Ninth Revision, e884.1; International Classification of Diseases, 10th Revision, w15.xx) from 2006 to 2018 as a Western Trauma Association multicenter investigation. Demographics, injury characteristics, and care delivery were analyzed. Comparative analyses were performed for climbing versus nonclimbing mechanisms. RESULTS: Over the 13-year study period, 1,176 wilderness fall victims were analyzed (301 climbers, 875 nonclimbers). Fall victims were male (76%), young (33 years), and moderately injured (Injury Severity Score, 12.8). Average fall height was 48 ft, and average rescue/transport time was 4 hours. Nineteen percent were intoxicated. The most common injury regions were soft tissue (57%), lower extremity (47%), head (40%), and spine (36%). Nonclimbers had a higher incidence of severe head and facial injuries despite having equivalent overall Injury Severity Score. On multivariate analysis, climbing remained independently associated with increased need for surgery but lower odds of composite intensive care unit admission/death. Contrary to studies of urban falls, height of fall in wilderness falls was not independently associated with mortality or Injury Severity Score. CONCLUSION: Wilderness falls represent a unique population with distinct patterns of predominantly soft tissue, head, and lower extremity injury. Climbers are younger, usually male, more often discharged home, and require more surgery but less critical care. LEVEL OF EVIDENCE: Epidemiological, Level IV.

Pseudomonas aeruginosa Alginate Benefits Staphylococcus aureus?

In this issue of Journal of Bacteriology, Price et al. show that the Pseudomonas aeruginosa-produced exopolysaccharide alginate protects Staphylococcus aureus by dampening the expression of P. aeruginosa virulence products that usually inhibit S. aureus respiration and cell membrane integrity when the two organisms compete in other environments (C. E. Price, D. G. Brown, D. H. Limoli, V. V. Phelan, and G. A. O'Toole, J Bacteriol 202:e00559-19, 2020, https://doi.org/10.1128/jb.00559-19). This is the first report that exogenously added alginate affects P. aeruginosa competition and provides a partial explanation for S. aureus and P. aeruginosa coinfections in cystic fibrosis.

AB569, a nontoxic chemical tandem that kills major human pathogenic bacteria.

Antibiotic-resistant superbug bacteria represent a global health problem with no imminent solutions. Here we demonstrate that the combination (termed AB569) of acidified nitrite (A-NO2-) and Na2-EDTA (disodium ethylenediaminetetraacetic acid) inhibited all Gram-negative and Gram-positive bacteria tested. AB569 was also efficacious at killing the model organism Pseudomonas aeruginosa in biofilms and in a murine chronic lung infection model. AB569 was not toxic to human cell lines at bactericidal concentrations using a basic viability assay. RNA-Seq analyses upon treatment of P. aeruginosa with AB569 revealed a catastrophic loss of the ability to support core pathways encompassing DNA, RNA, protein, ATP biosynthesis, and iron metabolism. Electrochemical analyses elucidated that AB569 produced more stable SNO proteins, potentially explaining one mechanism of bacterial killing. Our data implicate that AB569 is a safe and effective means to kill pathogenic bacteria, suggesting that simple strategies could be applied with highly advantageous therapeutic/toxicity index ratios to pathogens associated with a myriad of periepithelial infections and related disease scenarios.