Pseudomonas aeruginosa can be detected in a polymicrobial competition model using impedance spectroscopy with a novel biosensor

Electrochemical Impedance Spectroscopy (EIS) is a powerful technique that can be used to elicit information about an electrode interface. In this article, we highlight six principal processes by which the presence of microorganisms can affect impedance and show how one of these - the production of electroactive metabolites - changes the impedance signature of culture media containing Pseudomonas aeruginosa. EIS, was used in conjunction with a low cost screen printed carbon sensor to detect the presence of P. aeruginosa when grown in isolation or as part of a polymicrobial infection with Staphylococcus aureus. By comparing the electrode to a starting measurement, we were able to identify an impedance signature characteristic of P. aeruginosa. Furthermore, we are able to show that one of the changes in the impedance signature is due to pyocyanin and associated phenazine compounds. The findings of this study indicate that it might be possible to develop a low cost sensor for the detection of P. aeruginosa in important point of care diagnostic applications. In particular, we suggest that a development of the device described here could be used in a polymicrobial clinical sample such as sputum from a CF patient to detect P. aeruginosa

Medial opening wedge high tibial osteotomy: A retrospective review of patient outcomes over 10 years

Objectives: High tibial osteotomy (HTO) has become a well-established treatment for unicompartmental osteoarthritis of the knee. Over the last 30 years, various techniques have been introduced to advance this procedure. The purpose of this study is to review the outcomes of patients who received medial opening wedge HTO over the last ten years (2002-2012) using a modern, low profile, medially based fixation device. In addition, we sought to determine if obese patients had a less favorable outcome than their non-obese counterparts. Methods: Ninety-three patients were identified from a surgical database as having undergone a HTO for medial compartment osteoarthritis of the knee with varus mal-alignment. All procedures were performed by one of two fellowship trained orthopedic surgeons from 2002-2012 utilizing a low profile fixation device and identical surgical technique. Minimum follow-up was one year for inclusion in the study. Outcomes were measured using Lysholm and WOMAC scores. Radiographs were evaluated to determine delayed union or non-union at the osteotomy site and surveillance was undertaken to evaluate post operative complications. Results: 93 patients were identified from the database, 63 (70%) were available for follow-up and are included in this analysis. Average follow-up time was 48 months (range 17 to 137). There were 44 males and 19 females. The average age was 45 years old. The average final Lysholm and WOMAC scores were 66.4 (range: 13-100) and 18.6 (range: 0-86) respectively. There was no significant difference in reported Lysholm or WOMAC scores between obese (BMI \u3e30) and non-obese patients (p=.31;p=.69). Complications were as follows: 3 patients required a surgical lysis of adhesions, 2 patients developed an infection, and 1 patient experienced a delayed union. At final follow-up, 18 patients received additional treatment on the affected knee: 11 required removal of symptomatic hardware, 5 received viscosupplementation, 2 underwent a total knee replacement. Conclusion: Low profile, medial based devices used in the setting of HTO is an accepted treatment for unicompartmental osteoarthritis of the knee. At final follow-up, a majority of patients reported positive outcomes and few complications. 18 patients required additional treatment for osteoarthritis. In our analysis, obese patients faired equally as well as their non-obese counterparts, with no significant difference in outcomes scores or complication rate. Survivorship of high tibial osteotomy was excellent in this series, with only 2 patients having undergone total knee replacement at last follow-up. © The Author(s) 2015

Microbes Against Humanity, a workshop game for horrible students: using a creative card game in higher education microbiology teaching

Introducing creative workshops in higher education curricula, in addition to formal lectures, is an excellent way of reinforcing knowledge and encouraging creative thinking. In particular, the use of card games as a tool for inducing student engagement and enthusiasm has been reported to be a very effective approach. Here, we report an innovative card game-based workshop for use at the intermediate undergraduate level. The name of the game is Microbes Against Humanity and has been adapted from the widely known party game Cards Against Humanity, which is freely available under a creative commons licence. Overall, 64 students and two academics participated in this 2 h workshop. Our students found the workshop to be very enjoyable, considered it to be helpful for their learning and suggested interesting ideas for further improvement. In conclusion, it was shown that such exciting workshops can trigger students’ enthusiasm for microbiology and enhance their learning potential

Development of a diagnostic device to detect different pseudomonas aeruginosa phenotypes in medically relevant contexts

Pseudomonas aeruginosa, widely present in the environment, is well known for its ability to cause infection in immune compromised individuals. For example, P. aeruginosa is the leading cause of morbidity and mortality in patients with cystic fibrosis (CF). Here, we describe how Electrochemical Impedance Spectroscopy (EIS) can be used to detect the presence of four different strains of P. aeruginosa. Using a low cost, screen printed carbon electrode significant changes can be seen in impedance data in the presence of P. aeruginosa after 24 hours. Furthermore, through the use of a normalization technique whereby the phase angle of the impedance (a commonly used parameter) is divided by a starting measurement, it is possible to identify differences between a non-mucoid and mucoid strain of P. aeruginosa. Sensors based upon the techniques described here could be used in a number of healthcare scenarios, where there is a need for low cost, real time detection of P. aeruginosa, such as CF

Genomic plasticity of pathogenic Escherichia coli mediates D-serine tolerance via multiple adaptive mechanisms

Significance Pathogens ensure infection of favored sites in the body by responding to chemical signals. One chemical abundant in urine, the amino acid d -Ser, is toxic to EHEC and reduces expression of the machinery used for host cell attachment, making the bladder an unfavorable environment. We observed that under d -Ser stress, EHEC acquires genetic changes that lead to blocking d -Ser uptake into the cell or activating a silent enzyme for degrading d -Ser. This prevents growth inhibition and, critically, inhibits the repression of attachment machinery normally caused by d -Ser. These findings highlight the importance of pathogen evolution in determining how host molecules regulate colonization. These interactions underpin a process known as niche restriction that is important for pathogen success within the host

BAREFOOT RUNNING TRAINING: IMPLlCATtONS FOR JOINT STIFFNESS AND MUSCULAR CO-ACTWAlION

To determine the influence of barefoot training on neuromuscular w-activation of lower limb muscles on variables associated with injury risk during running. Trained shod runners (n=23) participated in a barefoot running program. Joint stiffness, agonist: antagonist co-activation and the co-activation index were calculated. A progressive barefoot training program induces longer co-activation of the shank complex and lower ankle stiffness in the barefoot condition. Footwear is implicated in changing injury risk factors whether soft tissue or bony related injuries. This paper suggests barefoot training as an avenue for rehabilitating ankle injuries as it promotes an even distribution of joint stillness and lower ankle stiffness when compared to shod running

Natural antibiofilm agents and the need for antibiofilm drug leads

Plant with medicinal property contains different types of bioactive compounds and these compounds are effective against certain diseases. Biofilm infection is a disease caused by biofilm which is associated with the respiratory and gastrointestinal infections. Biofilm-producing bacteria as such Pseudomonas aeruginosa strain PA14 is a serious treat in hospitals. The bacterium possesses many virulent factors that contributed to its pathogenesis and resistance thus caused the inhibition and removal of its biofilms a difficult task. This study therefore attempts to identify natural antibiofilm agents against the P. aeruginosa PA14 biofilms. The activity of plant extracts and subsequently purified compounds was evaluated using a stepwise separation process called bioassay-guided fractionation. The fractionation process involved the use of chromatographic techniques and compounds were identified using NMR, GC-MS and LC-MS. A total of four bioactive fractions namely (E333F1S1), (E341), (HA6) and (M338B) have been discovered with antibiofilm activity and were selected for further investigation. The active fraction from Ribes nigrum leaf (E333F1S1) contained mixtures of alkanes while active extract of Sambucus nigra flower (E341) contained a mixture of ursolic acid and oleanolic acid. The LC-MS analysis on Coriandrum sativum seeds (HA6) revealed the presence mixture of oxygenated monoterpenes, while another active fraction of C. sativum seeds (M338B) showed the presence of carboxylic acid, carboxylate, tetraone, glycerol, carbohydrate and fatty acids. Thus, the discovery of potential bioactive compounds from this study could be further investigated as antibiofilm drug leads to battle the infections by P. aeruginosa PA14 biofilm in the near future

The Genetics of Prey Susceptibility to Myxobacterial Predation:A Review, including an Investigation into Pseudomonas aeruginosa Mutations Affecting Predation by Myxococcus xanthus

Bacterial predation is a ubiquitous and fundamental biological process, which influences the community composition of microbial ecosystems. Among the best characterised bacterial predators are the myxobacteria, which include the model organism Myxococcus xanthus. Predation by M. xanthus involves the secretion of antibiotic metabolites and hydrolytic enzymes, which results in the lysis of prey organisms and release of prey nutrients into the extracellular milieu. Due to the generalist nature of this predatory mechanism, M. xanthus has a broad prey range, being able to kill and consume Gram-negative/positive bacteria and fungi. Potential prey organisms have evolved a range of behaviours which protect themselves from attack by predators. In recent years, several investigations have studied the molecular responses of a broad variety of prey organisms to M. xanthus predation. It seems that the diverse mechanisms employed by prey belong to a much smaller number of general "predation resistance" strategies. In this mini-review, we present the current state of knowledge regarding M. xanthus predation, and how prey organisms resist predation. As previous molecular studies of prey susceptibility have focussed on individual genes/metabolites, we have also undertaken a genome-wide screen for genes of Pseudomonas aeruginosa which contribute to its ability to resist predation. P. aeruginosa is a World Health Organisation priority 1 antibiotic-resistant pathogen. It is metabolically versatile and has an array of pathogenic mechanisms, leading to its prevalence as an opportunistic pathogen. Using a library of nearly 5,500 defined transposon insertion mutants, we screened for "prey genes", which when mutated allowed increased predation by a fluorescent strain of M. xanthus. A set of candidate "prey proteins" were identified, which shared common functional roles and whose nature suggested that predation resistance by P. aeruginosa requires an effective metal/oxidative stress system, an intact motility system, and mechanisms for de-toxifying antimicrobial peptides