Risk of bacteremia in hospitalised patients with inflammatory bowel disease: a 9-year cohort study

Bacterial amino acid chemotaxis: a widespread strategy with multiple physiological and ecological roles

Chemotaxis is the directed, flagellum-based movement of bacteria in chemoeffector gradients. Bacteria respond chemotactically to a wide range of chemoeffectors, including amino, organic, and fatty acids, sugars, polyamines, quaternary amines, purines, pyrimidines, aromatic hydrocarbons, oxygen, inorganic ions, or polysaccharides. Most frequent are chemotactic responses to amino acids (AAs), which were observed in numerous bacteria regardless of their phylogeny and lifestyle. Mostly chemoattraction responses are observed, although a number of bacteria are repelled from certain AAs. Chemoattraction is associated with the important metabolic value of AAs as growth substrates or building blocks of proteins. However, additional studies revealed that AAs are also sensed as environmental cues. Many chemoreceptors are specific for AAs, and signaling is typically initiated by direct ligand binding to their four-helix bundle or dCache ligand-binding domains. Frequently, bacteria possess multiple AA-responsive chemoreceptors that at times possess complementary AA ligand spectra. The identification of sequence motifs in the binding sites at dCache_1 domains has permitted to define an AA-specific family of dCache_1AA chemoreceptors. In addition, AAs are among the ligands recognized by broad ligand range chemoreceptors, and evidence was obtained for chemoreceptor activation by the binding of AA-loaded solute-binding proteins. The biological significance of AA chemotaxis is very ample including in biofilm formation, root and seed colonization by beneficial bacteria, plant entry of phytopathogens, colonization of the intestine, or different virulence-related features in human/animal pathogens. This review provides insights that may be helpful for the study of AA chemotaxis in other uncharacterized bacteria.

Bloodstream co-infection with Turicibacter sanguinis and Desulfovibrio desulfuricans in a patient with a flare of ulcerative colitis - A case report and review of the literature

Turicibacter sanguinis was isolated in 2002 from the blood of a patient with appendicitis. We report a bacteremia with T. sanguinis and Desulfovibrio desulfuricans in a patient with ulcerative colitis. T. sanguinis grew in thioglycolate media and identification was confirmed with 16S rRNA sequencing.

Bacterial vampirism mediated through taxis to serum

Bacteria of the family Enterobacteriaceae are associated with gastrointestinal (GI) bleeding and bacteremia and are a leading cause of death, from sepsis, for individuals with inflammatory bowel diseases. The bacterial behaviors and mechanisms underlying why these bacteria are prone to bloodstream entry remain poorly understood. Herein, we report that clinical isolates of non-typhoidal Salmonella enterica serovars, Escherichia coli, and Citrobacter koseri are rapidly attracted toward sources of human serum. To simulate GI bleeding, we utilized an injection-based microfluidics device and found that femtoliter volumes of human serum are sufficient to induce bacterial attraction to the serum source. This response is orchestrated through chemotaxis and the chemoattractant L-serine, an amino acid abundant in serum that is recognized through direct binding by the chemoreceptor Tsr. We report the first crystal structures of Salmonella Typhimurium Tsr in complex with L-serine and identify a conserved amino acid recognition motif for L-serine shared among Tsr orthologues. We find Tsr to be widely conserved among Enterobacteriaceae and numerous World Health Organization priority pathogens associated with bloodstream infections. Lastly, we find that Enterobacteriaceae use human serum as a source of nutrients for growth and that chemotaxis and the chemoreceptor Tsr provide a competitive advantage for migration into enterohemorrhagic lesions. We define this bacterial behavior of taxis toward serum, colonization of hemorrhagic lesions, and the consumption of serum nutrients as 'bacterial vampirism', which may relate to the proclivity of Enterobacteriaceae for bloodstream infections.

pH-responsive interface conversion efficient oral drug delivery platform for alleviating inflammatory bowel disease

A key challenge for the effective treatment of intestinal diseases, including inflammatory bowel disease (IBD), is to develop an oral drug delivery system that can resist gastric acid erosion and efficiently release drugs after rapid entry into the intestine. In the present work, we developed oral composite nanoparticles (MSZ@PRHS) consisting of a rough mesoporous silica (RHS) loaded with Mesalazine (MSZ) and a CAP polymer membrane for targeted relief of inflammation in colitis. At the pH values of the simulated stomach and small intestine, the release rate of MSZ from MSZ@PRHS was low, while at the pH values of the simulated colon, the release rate of MSZ was high. In dextran sulfate sodium salt (DSS)-induced acute colitis mouse model, compared with oral administration of the drug Mesalazine in the equivalent solution form, oral administration of PRHS loaded with drug-loaded nanoparticles can significantly alleviate the symptoms of inflammatory bowel disease, and improve the therapeutic effect. We propose that the intestinal microenvironment provides an interface for nanocomposites switch and a promising drug delivery platform for the management and treatment of many intestinal diseases, where controlled drug release and prolonged residence time are required.

Bacterial vampirism mediated through taxis to serum

Bacteria of the family Enterobacteriaceae are associated with gastrointestinal (GI) bleeding and bacteremia and are a leading cause of death, from sepsis, for individuals with inflammatory bowel diseases. The bacterial behaviors and mechanisms underlying why these bacteria are prone to bloodstream entry remains poorly understood. Herein, we report that clinical isolates of non-typhoidal Salmonella enterica serovars, Escherichia coli, and Citrobacter koseri are rapidly attracted toward sources of human serum. To simulate GI bleeding, we utilized a custom injection-based microfluidics device and found that femtoliter volumes of human serum are sufficient to induce the bacterial population to swim toward and aggregate at the serum source. This response is orchestrated through chemotaxis, and a major chemical cue driving chemoattraction is L-serine, an amino acid abundant in serum that is recognized through direct binding by the chemoreceptor Tsr. We report the first crystal structures of Salmonella Typhimurium Tsr in complex with L-serine and identify a conserved amino acid recognition motif for L-serine shared among Tsr orthologues. By mapping the phylogenetic distribution of this chemoreceptor we found Tsr to be widely conserved among Enterobacteriaceae and numerous World Health Organization priority pathogens associated with bloodstream infections. Lastly, we find that Enterobacteriaceae use human serum as a source of nutrients for growth and that chemotaxis and the chemoreceptor Tsr provides a competitive advantage for migration into enterohaemorrhagic lesions. We term this bacterial behavior of taxis toward serum, colonization of hemorrhagic lesions, and the consumption of serum nutrients, as 'bacterial vampirism' which may relate to the proclivity of Enterobacteriaceae for bloodstream infections.

A Case of Fungemia Caused by Postoperative Chronic Lumbar Intervertebral Disc Infection

Postoperative surgical site infection is one of the serious postoperative complications of spine surgery, especially fungal infections. Late-stage surgical site fungal infections often lack typical clinical symptoms and have a variable clinical presentation. In this case, the patient was a senior patient with usually only tolerable pain and discomfort, which was detected 2 years after the first surgery. Such cases are even rarer for fungal bloodstream infections caused by delayed postoperative chronic fungal osteomyelitis and deserve further study for early identification and intervention to minimize harm.

The role of oral bacteria in inflammatory bowel disease

Over the past two decades, the importance of the microbiota in health and disease has become evident. Pathological changes to the oral bacterial microbiota, such as those occurring during periodontal disease, are associated with multiple inflammatory conditions, including inflammatory bowel disease. However, the degree to which this association is a consequence of elevated oral inflammation or because oral bacteria can directly drive inflammation at distal sites remains under debate. In this Perspective, we propose that in inflammatory bowel disease, oral disease-associated bacteria translocate to the intestine and directly exacerbate disease. We propose a multistage model that involves pathological changes to the microbial and immune compartments of both the oral cavity and intestine. The evidence to support this hypothesis is critically evaluated and the relevance to other diseases in which oral bacteria have been implicated (including colorectal cancer and liver disease) are discussed.

A Rare Case of Escherichia coli Chest Wall Abscess With Rib Osteomyelitis in a Patient With Crohn's Disease

Primary chest wall abscess due to hematogenous spread is very rare and has seldom been documented in the literature, with most reported cases attributed to Mycobacterium tuberculosis. Prompt diagnosis and management with antibiotics, and evacuation of the abscess, is imperative as the infection can lead to systemic or disseminated infection, including erosion into surrounding bone if left untreated. We describe the case of a 67-year-old female with severe Crohn’s disease receiving anti-tumor necrosis factor-alpha (TNF-α) therapy, Etanercept presenting with localized Escherichia coli (E. coli) chest wall abscess with erosion into the surrounding rib. This case highlights a rare clinical entity, chest wall abscess, which is also an unusual site of E. coli infection. Only three previous cases of E. coli primary chest wall abscess can be found in the published literature. This case also highlights a possible association of severe Crohn’s disease predisposing to complicated soft tissue infection.

Are hospitalized patients with inflammatory bowel disease at increased risk of invasive bacterial infections? Results from POLIBD 3-year cohort study

The aim of this study was to determine the dominant species of bacteria found in blood cultures collected from patients under treatment in the tertiary inflammatory bowel disease (IBD) center in Poland. The dominant pathogen isolated from blood in patients with IBD was Staphylococcus epidermidis MRCNS (MRCNS—methicillin-resistant coagulase-negative Staphylococcus), a strain resistant to all beta-lactam antibiotics (penicillins, penicillins with B-lactamase inhibitor, cephalosporins and carbapenems). The second most commonly isolated pathogen found in the blood samples was Escherichia coli. Blood cultures were found to be positive for these pathogens more frequently in male patients (90.0%). An increased risk of bacteremia in IBD patients was associated with prolonged hospitalization.