As antibiotic resistance continues to increase globally, there is an urgency for novel, non‐antibiotic approaches to control chronic drug‐resistant infections, particularly those associated with polymicrobial biofilm formation in chronic wounds. Also needed are clinically relevant polymicrobial biofilm models that can be utilized to assess the efficacy of innovative therapeutics against mature biofilms. We successfully developed a highly reproducible porcine ex vivo skin wound polymicrobial biofilm model using clinical isolates of multidrug‐resistant Pseudomonas aeruginosa, methicillin‐resistant Staphylococcus aureus, and Candida albicans. This ex vivo biofilm model was then used to assess the antimicrobial and antibiofilm properties of an easily fabricated chitosan hydrogel incorporating the natural antimicrobial peptide epsilon‐poly‐L‐lysine. Antimicrobial activity was evaluated against planktonic cultures in vitro and against mature biofilms ex vivo. The antibiofilm efficiency of the hydrogels was especially pronounced against Pseudomonas aeruginosa, whose counts were reduced by 99.98% after 2 hours in vitro and by 99.94% after treatment for 24 hours when applied to 24 hour ex vivo polymicrobial wound biofilms. The activity of the hydrogels was lower against Staphylococcus aureus and ineffective against Candida albicans. Gram, Hucker‐Twort staining of paraffin sections revealed balanced polymicrobial communities in mature 48 hour untreated biofilms. Treatment of 48 or 72 hour biofilms for 2 or 3 days with hydrogels that were applied within 5 hours after inoculation resulted in an impressive 96% and 97% reduction in biofilm thickness compared to untreated biofilms, respectively (P < .001). Likewise, topical gel treatment for 24 hours reduced biofilm thickness by 84% and 70%, respectively, when applied to mature biofilms at 24 and 48 hours after inoculation (P < .001). Thus, this ex vivo wound biofilm model provides a useful means to assess the efficacy of novel treatments to prevent and eradicate polymicrobial biofilms consisting of multidrug‐resistant Pseudomonas aeruginosa, methicillin‐resistant Staphylococcus aureus, and Candida albicans.

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Introduction and importance Appendicitis is an extremely common surgical problem, especially in the pediatric population. However, leukemic infiltration of the appendix is rare and even more so is having acute appendicitis as the initial manifestation. Case presentation The patient is a 2-year-old female with multiple febrile illnesses since birth, who presented to the emergency department with a 3-day history of abdominal pain, fever, and decreased appetite. Ultrasound of her right lower quadrant was consistent with acute appendicitis. A laparoscopic appendectomy was performed successfully without complication. However, pathological examination of the specimen revealed an appendix with partial involvement of B-lymphoblastic lymphoma/leukemia in a background of lymphoid hyperplasia. This prompted referral to a pediatric hematologist/oncologist. Further workup revealed abnormal immature cells on peripheral blood flow cytometry. Bone marrow biopsy confirmed a diagnosis of B-cell acute lymphoblastic leukemia. Clinical discussion Though acute appendicitis is very common and management is well documented, it is rare for pathological examination to uncover leukemia as an underlying etiology and to have acute appendicitis as the initial manifestation of hematologic malignancy. To our knowledge, very few similar events have occurred and been documented in the medical literature. Conclusion Physicians and surgeons should be aware that, though quite rare, leukemic infiltration of the appendix can occur and should be considered in the differential diagnosis of acute appendicitis. Notably, pathologic examination of the appendix may be particularly informative. Diligent follow-up of abnormal pathology is crucial in cases suggestive of underlying hematologic malignancy.

Managing pulmonary edema is critical to maintaining blood oxygenation and perfusion for adequate tissue oxygen delivery after acute lung injury. While it is well recognized that renal failure often leads to complications of nephrogenic pulmonary edema, how the regulation of lung fluid is changed during altered renal function in conditions of traumatic injury is poorly understood. We hypothesized that control of lung water balance after a traumatic blunt force lung injury accompanied by a renal response to hemorrhage and hypotension would be different than after simple disruption of the alveolar‐capillary liquid barrier interface. Hence, we compared the changes in effective lung water index (ELWI, measured by the Pulse Ion Contour Cardiac Output (PICCO), Getinge) method in a pig model of Traumatic Acute Lung Injury (TALI, n=9), and a model of diffuse alveolar‐capillary barrier disruption with oleic acid (OA, n=5), versus a control group (n=10). Anesthetized, mechanically ventilated, Yorkshire cross male and female pigs (body weight 27.0 +/‐ 0.6 kg) were catheterized with a Swan Ganz catheter for measurement of pulmonary artery pressure and cardiac output determination by thermodilution. Pulmonary function, hemodynamics, and urinary output were examined before and after localized blunt right chest trauma (TALI), or oleic acid injection into the main pulmonary artery (OA 0.3 ml in 50% w/v ethanol). Pulmonary vasoconstriction was induced in the acute lung injury groups as indicated by an increase in pulmonary to systemic vascular resistance ratios in TALI (0.37 +/‐ 0.03) and OA (0.34 +/‐0.08) compared to controls (0.21+/‐0.02). TALI resulted in a decrease in mean arterial pressure (MAP, 46+/‐4 mmHg) compared to controls (60 +/‐2 mmHg) or OA (62+/‐3 mm Hg). In all groups ELWI remained steady compared to pre‐injury baseline. In the OA and control groups, circulating vasopressin decreased over the time course of the experiment (p<0.01) but did not decrease in the TALI group in accordance with the injury‐induced hemorrhage and decreased MAP. Accordingly, urine flow decreased in the TALI group compared to OA and controls. Fractional excretion of water decreased in the OA and control groups, (p<0.01) but remained unchanged in TALI, indicating retention of water in OA and controls compared to TALI. The overall maintenance of ELWI despite differences in renal water handling in TALI compared to controls suggest that protection against pulmonary edema needs to be considered in treatment of hypotension with fluid resuscitation in traumatic lung injury.

Biofilms are a known important contributor to the infectious complications associated with prosthetic mesh implantation. Previous studies have demonstrated the formation of monomicrobial biofilms on surgical mesh materials by different bacterial species in vitro, but a paucity of data exists examining polymicrobial biofilm formation by antibiotic-resistant organisms, which may be more clinically relevant. Therefore, the aim of this study was to evaluate the ability of three clinical bacterial and fungal isolates to form mixed-species and single-species biofilms on five synthetic implant materials in vitro, including monofilament polypropylene, monofilament polyester, multifilament polyester, monofilament polytetrafluoroethylene (PTFE), and silicone. Methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Pseudomonas aeruginosa, and Candida albicans (alone or in combination) were inoculated into culture medium containing meshes and allowed to attach and propagate into mature biofilms for 48 hours at 37 o C. Additional samples were inoculated with Staphylococcus epidermidis for comparison. Biofilm biomass and the number of viable cells were quantified by crystal violet staining and colony forming units (CFU) counting, respectively. Images of polymicrobial biofilms were obtained using fluorescence microscopy of FM ® 1-43-stained meshes. All materials investigated were capable of harboring biofilms, but the relative abundance was dependent upon both material and organism type. Overall, PTFE meshes exhibited the highest levels of polymicrobial biofilm formation. When comparing monomicrobial biofilms, Pseudomonas aeruginosa demonstrated greater biomass than MRSA and Staphylococcus epidermidis on PTFE, polypropylene, and monofilament polyester, while MRSA and Staphylococcus epidermidis biomass did not differ significantly among mesh types. Thus MRSA, Pseudomonas aeruginosa, and Candida albicans can cooperatively form mature biofilms on surgical implant materials, but different mesh constructs vary in their susceptibility to biofilm formation depending upon the organism(s) present. This suggests that the type of implant material chosen for surgical procedures may affect the patient's wound healing response and clinical outcome, particularly when used in a contaminated environment.