Abstract
The worldwide increase of antimicrobial resistance (AMR) is a serious threat to human health. To avert the spread of AMR, fast reliable diagnostics tools that facilitate optimal antibiotic ...stewardship are an unmet need. In this regard, Raman spectroscopy promises rapid label- and culture-free identification and antimicrobial susceptibility testing (AST) in a single step. However, even though many Raman-based bacteria-identification and AST studies have demonstrated impressive results, some shortcomings must be addressed. To bridge the gap between proof-of-concept studies and clinical application, we have developed machine learning techniques in combination with a novel data-augmentation algorithm, for fast identification of minimally prepared bacteria phenotypes and the distinctions of methicillin-resistant (MR) from methicillin-susceptible (MS) bacteria. For this we have implemented a spectral transformer model for hyper-spectral Raman images of bacteria. We show that our model outperforms the standard convolutional neural network models on a multitude of classification problems, both in terms of accuracy and in terms of training time. We attain more than 96% classification accuracy on a dataset consisting of 15 different classes and 95.6% classification accuracy for six MR–MS bacteria species. More importantly, our results are obtained using only fast and easy-to-produce training and test data.
Staphylococcus aureus is the cause of serious vascular infections such as sepsis and endocarditis. These infections are notoriously difficult to treat, and it is believed that the ability of S. ...aureus to invade endothelial cells and persist intracellularly is a key mechanism for persistence despite ongoing antibiotic treatment. Here, we used dual RNA sequencing to study the simultaneous transcriptional response of S. aureus and human endothelial cells during in vitro infections. We revealed discrete and shared differentially expressed genes for both host and pathogen at the different stages of infection. While the endothelial cells upregulated genes involved in interferon signalling and antigen presentation during late infection, S. aureus downregulated toxin expression while upregulating genes related to iron scavenging. In conclusion, the presented data provide an important resource to facilitate functional investigations into host-pathogen interaction during S. aureus invasive infection and a basis for identifying novel drug target sites.
A Porcine Model for Urinary Tract Infection Nielsen, Thomas Kastberg; Petersen, Nicky Anúel; Stærk, Kristian ...
Frontiers in microbiology,
11/2019, Letnik:
10
Journal Article
Recenzirano
Odprti dostop
Urinary tract infection (UTI) is the most common bacterial infectious disease with a high frequency of recurrence and the leading cause of septicemia.
experimentation has contributed significantly to ...the present-day knowledge on UTI pathogenesis. This research has traditionally been based on murine models of UTI. Occasional conflicting results between UTI in mice and humans and increasing skepticism toward small rodent models in general warrant the need of novel large-animal infection models that better resemble the anatomy and physiology of humans, and thus better mimic the course of infection in humans. Here, we report, to our knowledge, the first large-animal model of cystitis. The model is based on pigs, and the protocol supports the establishment of persistent, non-ascending infection in this animal and is established without invasive surgical procedures, pain, and discomfort for the animal. The course of infection is monitored by cystoscopy, microscopy of bladder biopsies, and biochemical analysis of urine and blood samples. At termination, harvested whole bladders from infected pigs are analyzed for microbiological colonization using microscopy, histology, and viable bacterial counts. The model is a useful tool in future studies of UTI pathogenesis and opens up novel possibilities to bridge the current knowledge obtained from small-animal UTI models to UTI pathogenesis in humans.
Background:
Catheter-associated urinary tract infection (CAUTI) is a frequent community-acquired infection and the most common nosocomial infection. Here, we developed a novel antimicrobial catheter ...concept that utilizes a silicone-based interpenetrating polymer network (IPN) as balloon material to facilitate a topical slow-release prophylaxis of antibacterial agents across the balloon to the urinary bladder.
Methods:
The balloon material was achieved by modifying low shore hardness silicone tubes with a hydrogel interpenetrating polymer in supercritical CO
2
using the sequential method. Release properties and antibacterial efficacy of the IPN balloon treatment concept was investigated
in vitro
and in a porcine CAUTI model developed for the study. In the latter, Bactiguard Infection Protection (BIP) Foley catheters were also assessed to enable benchmark with the traditional antimicrobial coating principle.
Results:
Uropathogenic
Escherichia coli
was undetectable in urinary bladders and on retrieved catheters in the IPN treatment group as compared to control that revealed significant bacteriuria (>10
5
colony forming units/ml) as well as catheter-associated biofilm. The BIP catheters failed to prevent
E. coli
colonization of the bladder but significantly reduced catheter biofilm formation compared to the control.
Conclusion:
The IPN-catheter concept provides a novel, promising delivery route for local treatment in the urinary tract.
In 2011, as the first European country, Denmark introduced the non-organ-specific cancer patient pathway (CPP) for patients presenting with non-specific symptoms and signs of cancer (NSSC). The ...proportion of patients with cancer over time is unknown.
A retrospective cohort study of all patients with a NSSC-CPP investigational course in the province of Funen to the Diagnostic Centre in Svendborg from 2014 to 2021 was performed to evaluate the proportion of patients with cancer and serious disease over time.
A total of 6698 patients were referred to the NSSC-CPP of which 20.2% had cancer. While the crude referral rate increased from 114 per 100,000 people in 2014 and stabilised to around 214 in 2017-2021, the cancer detection rate of the total yearly new cancers in Funen diagnosed through the NSSC-CPP in DC Svendborg increased from 3 to 6%.
With now high and stable conversion and crude referral rates, the NSSC-CPP is one of the largest CPPs in Denmark as measured by the number of new cancer cases found. Similar urgent referral programmes in other countries might fill an unmet medical need for patients presenting with serious non-specific symptoms and signs of cancer in general practice.
Experiments in murine models of urinary tract infection (UTI) show that uropathogenic Escherichia coli (UPEC) form bacterial reservoirs in the bladder tissue that can survive beta lactam antibiotics ...and give rise to reinfection. The observed reinfection cascade suggests intracellular bacterial persistence as a possible explanation for recurrent UTI in humans. To test this hypothesis in an animal model closer to humans, we here investigated whether UPEC infecting the bladders of experimentally inoculated pigs are able to survive standard oral mecillinam treatment. Moreover, we analyzed the infected pig bladders by microscopy for the presence of intracellular UPEC colonies.
Seven pigs were experimentally inoculated with the UPEC cystitis strain, UTI89, to induce cystitis. After 5 days of infections, a 3-day oral treatment with the extracellularly active β-lactam, mecillinam, was initiated. The infection was monitored with regular urine and blood samples. When terminated, whole bladders were removed and homogenized to quantify viable intracellular bacteria. In addition, two pigs were inoculated with UTI89pMAN01 constitutively expressing green fluorescent protein and the bladders subsequently analyzed by microscopy for bacterial location and morphology.
Experimental inoculation resulted in cystitis in all animals. After 3-day treatment with mecillinam, no viable UPEC were detectable in urine or bladder homogenates. Microscopy analysis of pig bladders at 12 h post infection, revealed no detectable intracellular bacterial colonies and no filamentous UPEC phenotypes were identified.
Pigs experimentally infected with UPEC completely clear their infection upon mecillinam treatment, which contrasts earlier findings from similar experiments in mice. Moreover, the hallmarks of induced UTI in mice, i.e. intracellular bacterial communities and bacterial filamentation, could not be identically reproduced in a pig model of acute UTI. This result suggests that significant differences might exist between UTI in mice and larger mammals, and therefore perhaps also between mice and humans. Additional studies are needed to reveal details on the Escherichia coli acute UTI pathogenesis cascade in larger mammals to assess to which extent observations in mice can be transferred to humans.
Display omitted
•Oral mecillinam effectively clears uropathogenic E. coli from the bladder of pigs.•Viable bacteria are undetectable in homogenized bladder tissues.•Intracellular bacterial communities are undetectable after 12 h cystitis in pigs.•Hallmarks of E. coli pathogenesis in mice could not be reproduced in pigs.
Most uropathogenic
(UPEC) express type-1 fimbriae (T1F), a key virulence factor for urinary tract infection (UTI) in mice. Evidence that conclusively associates this pilus with uropathogenesis in ...humans has, however, been difficult to obtain. We used an experimental porcine model of cystitis to assess the role of T1F in larger mammals more closely related to humans. Thirty-one pigs were infected with UPEC strain UTI89 or its T1F deficient mutant, UTI89Δ
, at inoculum titres of 10
to 10
colony forming units per millilitre. Urine and blood samples were collected and analysed 7 and 14 days post-inoculation, and whole bladders were removed at day 14 and analysed for uroepithelium-associated UPEC. All animals were consistently infected and reached high urine titres independent of inoculum titre. UTI89Δ
successfully colonized the bladders of 1/6 pigs compared to 6/6 for the wild-type strain. Intracellular UPEC were detectable in low numbers in whole bladder explants. In conclusion, low doses of UPEC are able to establish robust infections in pigs, similar to what is presumed in humans. T1F are critical for UPEC to surpass initial bottlenecks during infection but may be dispensable once infection is established. While supporting the conclusions from mice studies regarding a general importance of T1F in successfully infecting the host, the porcine UTI models' natural high, more human-like, susceptibility to infection, allowed us to demonstrate a pivotal role of T1F in initial establishment of infection upon a realistic low-inoculum introduction of UPEC in the bladder.
is a major human pathogen in catheter-related infections. Modifying catheter material with interpenetrating polymer networks is a novel material technology that allows for impregnation with drugs and ...subsequent controlled release. Here, we evaluated the potential for combining this system with plectasin derivate NZ2114 in an attempt to design an
biofilm-resistant catheter. The material demonstrated promising antibiofilm properties, including properties against methicillin-resistant
, thus suggesting a novel application of this antimicrobial peptide.
Surgical site infections (SSIs) are among the most frequent healthcare-associated infections, resulting in high morbidity, mortality, and cost. While correct hygiene measures and prophylactic ...antibiotics are effective in preventing SSIs, even in modern healthcare settings where recommended guidelines are strictly followed, SSIs persist as a considerable problem that has proven hard to solve. Surgical procedures involving the implantation of foreign bodies are particularly problematic due to the ability of microorganisms to adhere to and colonize the implanted material and form resilient biofilms. In these cases, SSIs may develop even months after implantation and can be difficult to treat once established. Locally applied antibiotics or specifically engineered implant materials with built-in antibiotic-release properties may prevent these complications and, ultimately, require fewer antibiotics compared to those that are systemically administered. In this study, we demonstrated an antimicrobial material concept with intended use in artificial vascular grafts. The material is a silicone–hydrogel interpenetrating polymer network developed earlier for drug-release catheters. In this study, we designed the material for permanent implantation and tested the drug-loading and drug-release properties of the material to prevent the growth of a typical causative pathogen of SSIs, Staphylococcus aureus. The novelty of this study is demonstrated through the antimicrobial properties of the material in vitro after loading it with an advantageous combination, minocycline and rifampicin, which subsequently showed superiority over the state-of-the-art (Propaten) artificial graft material in a large-animal study, using a novel porcine tissue-implantation model.
The worldwide increase of antimicrobial resistance (AMR) is a serious threat to human health. To avert the spread of AMR, fast reliable diagnostics tools that facilitate optimal antibiotic ...stewardship are an unmet need. In this regard, Raman spectroscopy promises rapid label- and culture-free identification and antimicrobial susceptibility testing (AST) in a single step. However, even though many Raman-based bacteria-identification and AST studies have demonstrated impressive results, some shortcomings must be addressed. To bridge the gap between proof-of-concept studies and clinical application, we have developed machine learning techniques in combination with a novel data-augmentation algorithm, for fast identification of minimally prepared bacteria phenotypes and the distinctions of methicillin-resistant (MR) from methicillin-susceptible (MS) bacteria. For this we have implemented a spectral transformer model for hyper-spectral Raman images of bacteria. We show that our model outperforms the standard convolutional neural network models on a multitude of classification problems, both in terms of accuracy and in terms of training time. We attain more than 96\(\%\) classification accuracy on a dataset consisting of 15 different classes and 95.6\(\%\) classification accuracy for six MR-MS bacteria species. More importantly, our results are obtained using only fast and easy-to-produce training and test data
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