Hypervirulent hypermucoviscous Klebsiella pneumoniae strains have emerged as clinically important pathogens causing invasive infections. K. pneumoniae osteomyelitis is uncommon in adult patients, and may mimic bone tumors on presentation. We report a patient with left rectus femoris muscle abscess and acute osteomyelitis of the left femur due to hypermucoviscous K. pneumoniae with negative blood culture, who was initially thought to have left thigh tumor. The patient\'s infection resolved with surgical drainage and debridement and intravenous and antibiotic therapy.

Psoriasis and inflammatory bowel disease (IBD) are both chronic inflammatory diseases occurring in the skin and gut, respectively. It is well established that psoriasis and IBD have high concordance rates, and similar changes in immune cells and microbiome composition have been reported in both conditions. To study this connection, we used a combination murine model of psoriatic dermatitis and colitis in which mice were treated topically with the Toll-like receptor 7 agonist imiquimod (IMQ) and fed dextran sulfate sodium (DSS).
We applied IMQ topically to B6 mice (IMQ mice) and subsequently fed them 2% DSS in their drinking water. Disease activity and immune cell phenotypes were analyzed, and the microbial composition of fecal samples was investigated using 16S ribosomal RNA sequencing. We transplanted feces from IMQ mice to germ-free IQI/Jic (IQI) mice and fed them DSS to assess the effect of the gut microbiome on disease.
We first confirmed that IMQ mice showed accelerated DSS colitis. IMQ mice had decreased numbers of IgD+ and IgM+ B cells and increased numbers of non-cytokine-producing macrophages in the gut. Moreover, the gut microbiomes of IMQ mice were perturbed, with significant reductions of Lactobacillus johnsonii and Lactobacillus reuteri populations. Germ-free mice transplanted with feces from IMQ mice, but not with feces from untreated mice, also developed exacerbated DSS colitis.
These results suggest that skin inflammation may contribute to pathogenic conditions in the gut via immunologic and microbiological changes. Our finding of a novel potential skin-gut interaction provides new insights into the coincidence of psoriasis and IBD.

Antibiotic (ABx) therapy is associated with increased risk for Crohn\'s disease but underlying mechanisms are unknown. We observed high fecal serine protease activity (PA) to be a frequent side effect of ABx therapy. The aim of the present study was to unravel whether this rise in large intestinal PA may promote colitis development via detrimental effects on the large intestinal barrier.
Transwell experiments were used to assess the impact of high PA in ABx-treated patients or vancomycin/metronidazole-treated mice on the epithelial barrier. Serine protease profiling was performed using liquid chromatography-mass spectrometry/mass spectrometry analysis. The impact of high large intestinal PA on the intestinal barrier in wild-type and interleukin (IL)10-/- mice and on colitis development in IL10-/- mice was investigated using vancomycin/metronidazole with or without oral serine protease inhibitor (AEBSF) treatment.
The ABx-induced, high large intestinal PA was caused by significantly increased levels of pancreatic proteases and impaired epithelial barrier integrity. In wild-type mice, the rise in PA caused a transient increase in intestinal permeability but did not affect susceptibility to chemically induced acute colitis. In IL10-/- mice, increased PA caused a consistent impairment of the intestinal barrier associated with inflammatory activation in the large intestinal tissue. In the long term, the vancomycin/metronidazole-induced lasting increase in PA aggravated colitis development in IL10-/- mice.
High large intestinal PA is a frequent adverse effect of ABx therapy, which is detrimental to the large intestinal barrier and may contribute to the development of chronic intestinal inflammation in susceptible individuals.

Extra-intestinal pathogenic Escherichia coli (ExPEC) are a significant cause of urinary tract infections and bacteraemia worldwide. Currently no single virulence factor or ExPEC lineage has been identified as the sole contributor to severe extra-intestinal infection and/or urosepsis. Galleria mellonella has recently been established as a simple model for studying the comparative virulence of ExPEC. In this study we investigated the virulence of 40 well-characterized ExPEC strains, in G. mellonella, by measuring mortality (larvae survival), immune recognition/response (melanin production) and cell damage (lactate dehydrogenase production). Although mortality was similar between urinary and bloodstream isolates, it was heightened for community-associated infections, complicated UTIs and urinary-source bacteraemia. Isolates of ST131 and those possessing afa/dra, ompT and serogroup O6 were also associated with heightened virulence.