Urinary ATP and visualization of intracellular bacteria: a superior diagnostic marker for recurrent UTI in renal transplant recipients?

Detection of phosphates in water utilizing a Eu3+-mediated relay mechanism

Fluorescent carboxyamidoquinolines form ensembles with Eu3+ that can be successfully leveraged in sensing of phosphates showing off–on fluorescence signaling.

The importance of intracellular bacterial biofilm in infectious diseases

Various bacterial species, previously known as extracellular pathogens, can reside inside different host cells by adapting to intracellular modes by forming microbial aggregates with similar characteristics to bacterial biofilms. Additionally, bacterial invasion of human cells leads to failure in antibiotic therapy, as most conventional anti-bacterial agents cannot reach intracellular biofilm in normal concentrations. Various studies have shown that bacteria such as uropathogenic Escherichia coli, Pseudomonas aeruginosa, Borrelia burgdorferi,Moraxella catarrhalis, non-typeable Haemophilus influenzae, Streptococcus pneumonia, and group A Streptococci produce biofilm-like structures within the host cells. For the first time in this review, we will describe and discuss the new information about intracellular bacterial biofilm formation and its importance in bacterial infectious diseases.

Bacterial Biofilm and its Role in the Pathogenesis of Disease

Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.

Invasion of Host Cells and Tissues by Uropathogenic Bacteria

Within the mammalian urinary tract uropathogenic bacteria face many challenges, including the shearing flow of urine, numerous antibacterial molecules, the bactericidal effects of phagocytes, and a scarcity of nutrients. These problems may be circumvented in part by the ability of uropathogenic Escherichia coli and several other uropathogens to invade the epithelial cells that line the urinary tract. By entering host cells, uropathogens can gain access to additional nutrients and protection from both host defenses and antibiotic treatments. Translocation through host cells can facilitate bacterial dissemination within the urinary tract, while the establishment of stable intracellular bacterial populations may create reservoirs for relapsing and chronic urinary tract infections. Here we review the mechanisms and consequences of host cell invasion by uropathogenic bacteria, with consideration of the defenses that are brought to bear against facultative intracellular pathogens within the urinary tract. The relevance of host cell invasion to the pathogenesis of urinary tract infections in human patients is also assessed, along with some of the emerging treatment options that build upon our growing understanding of the infectious life cycle of uropathogenic E. coli and other uropathogens.

A Case-Control Study to Determine the Prognostic Features of Salivary Epithelial Cells in Periodontitis

Periodontitis-a biofilm-induced immunoinflammatory pathology-often progresses gradually, exhibiting periodic bursts and resolution. Exfoliating oral epithelial cells act as reservoirs for key periodontal pathogens, facilitating reinfection or infection of new sites. Since saliva is a rich source of oral epithelial cells, we hypothesized that the microbial and functional profile of salivary epithelial cells (SECs) will reflect the in situ host response and disease severity. We used a case-control study design. Unstimulated whole saliva was collected from 20 chronic periodontitis patients and 20 healthy controls in accordance with the institutional review board. The isolated SECs were assessed for viability by trypan blue exclusion. Gram-stained SECs were analyzed by ImageJ, and Gram stain index (GSI) per SEC was calculated. Equal numbers of SECs from each sample were exposed to 2 periodontal pathogens- Porphyromonas gingivalis and Fusobacterium nucleatum-in biofilm or planktonic formulations at varying proportions. Cytokines in culture supernatants were assessed by ELISA (enzyme-linked immunosorbent assay). Additionally, soluble Toll-like receptor 2 (sTLR-2)-a pattern recognition receptor capable of binding microbial ligands associated with periodontitis-was measured in clarified saliva by ELISA. An increased number of SECs, a higher GSI/SEC, and a lower sTLR-2 were observed in periodontitis saliva as compared with healthy saliva. SECs from periodontitis saliva secreted higher amounts of interleukin 8 in response to P. gingivalis, and the presence of F. nucleatum dampened the response. Nonsurgical periodontal treatment improved clinical parameters, reduced the number of SECs, decreased GSI/SEC, and increased sTLR-2 in clarified saliva. In conclusion, our data suggest that SECs can provide a phenotypically distinct individualized resource for assessing epithelial response to pathogens in the course of periodontal disease. Furthermore, correlation between the sTLR-2 and GSI/SEC suggests that the expression profile of epithelial and soluble Toll-like receptor could provide an indirect measure of periodontal disease-associated dysbiosis. Knowledge Transfer Statement: The results of this study can be used for prognostic evaluation of chronic periodontitis in response to therapy and provide an opportunity for early identification of poor responders. A chip-based simple test incorporating the identified salivary epithelial cell characteristics can be developed and validated for future clinical applications, especially for monitoring patients with increased susceptibility for refractory and/or recurrent periodontitis.

Altered urothelial ATP signaling in a major subset of human overactive bladder patients with pyuria

Overactive Bladder (OAB) is an idiopathic condition, characterized by urgency, urinary frequency, and urgency incontinence, in the absence of routinely traceable urinary infection. We have described microscopic pyuria (≥10 wbc/μl) in patients suffering from the worst symptoms. It is established that inflammation is associated with increased ATP release from epithelial cells, and extracellular ATP originating from the urothelium following increased hydrostatic pressure is a mediator of bladder sensation. Here, using bladder biopsy samples, we have investigated urothelial ATP signaling in OAB patients with microscopic pyuria. Basal, but not stretch-evoked, release of ATP was significantly greater from the urothelium of OAB patients with pyuria than from non-OAB patients or OAB patients without pyuria (<10 wbc/μl). Basal ATP release from the urothelium of OAB patients with pyuria was inhibited by the P2 receptor antagonist suramin and abolished by the hemichannel blocker carbenoxolone, which differed from stretch-activated ATP release. Altered P2 receptor expression was evident in the urothelium from pyuric OAB patients. Furthermore, intracellular bacteria were visualized in shed urothelial cells from ∼80% of OAB patients with pyuria. These data suggest that increased ATP release from the urothelium, involving bacterial colonization, may play a role in the heightened symptoms associated with pyuric OAB patients.

Intracellular Bacterial Communities: A Potential Etiology for Chronic Lower Urinary Tract Symptoms

Patients with persistent lower urinary tract symptoms and negative urine cultures are often difficult to treat. Infection may go undetected in these patients because the concentrations of bacteria in their urine are beneath the threshold of standard urine culture techniques. Empiric treatment may result in temporary relief, followed by recurrent symptoms. Occult and recurrent urinary tract infection may be due to both invasion of the bladder wall by uropathogenic Escherichia coli and the formation of biofilm-like intracellular bacterial communities. This review examines emerging evidence for a role of intracellular bacterial communities in human infection.