The Efficacy of Selected Probiotic Strains and Their Combination to Inhibit the Interaction of Adherent-Invasive Escherichia coli (AIEC) with a Co-Culture of Caco-2:HT29-MTX Cells.

The gastrointestinal tract's microbiota plays a crucial role in human health, with dysbiosis linked to the development of diseases such as inflammatory bowel disease (IBD). Whilst the pathogenic mechanisms underlying IBD remain poorly characterised, adherent-invasive Escherichia coli (AIEC) has been implicated as a microbiological factor in disease pathogenesis. These strains show an enhanced ability to diffusely adhere to and invade intestinal epithelial cells, along with the ability to survive and replicate within macrophages. Probiotics, such as Lactobacillus strains, have been identified as potential treatment options due to their abilities to compete with pathogens for binding sites and regulate the host immune response. In this study, we used four well-characterised Lactobacillus strains and their combination to test their ability to inhibit the adhesion, invasion, and translocation of a well-characterized AIEC strain, F44A-1, in a co-culture of Caco-2 and HT29-MTX cell lines representing the gut epithelium. The results demonstrated that the pre-inoculation of the probiotic candidates 90 min prior to the introduction of the AIEC was more effective in inhibiting AIEC interaction than the co-inoculation of the strains. While the individual probiotic strains greatly reduced AIEC colonisation and invasion of the co-cultured cells, their combination was only more effective in reducing the translocation of the AIEC. These results suggest that probiotics are more effective when used prophylactically against pathogens and that the combination of strains may enhance their efficacy against AIEC translocation once used as a prophylactic measure.

Efficacy of Selected Live Biotherapeutic Candidates to Inhibit the Interaction of an Adhesive-Invasive Escherichia coli Strain with Caco-2, HT29-MTX Cells and Their Co-Culture.

Adherent-invasive Escherichia coli (AIEC) has been implicated as a microbiological factor in the pathogenesis of inflammatory bowel disease (IBD). We evaluated the ability of six live biotherapeutic products (LBPs) to inhibit the interaction of an AIEC strain to three cell lines representing human gut epithelium. Co-inoculation of LBPs with AIEC showed a reduction in adhesion (up to 73%) and invasion of AIEC (up to 89%). Pre-inoculation of LBPs in HT-29-MTX and Caco-2 cells before challenging with AIEC further reduced the adhesion and invasion of the AIEC, with three LBPs showing significantly (p < 0.0001) higher efficiency in reducing the adhesion of AIEC. In co-inoculation experiments, the highest reduction in adhesion (73%) of AIEC was observed in HT-29-MTX cells, whereas the highest reduction in invasion (89%) was seen in HT-29-MTX and the co-culture of cells. Pre-inoculation of LBPs further reduced the invasion of AIEC with highest reduction (97%) observed in co-culture of cells. Our results indicated that whilst there were differences in the efficacy of LBPs, they all reduced interaction of AIEC with cell lines representing gut epithelium. Their efficiency was higher when they were pre-inoculated onto the cells, suggesting their potential as candidates for alleviating pathogenesis of AIEC in patients with IBD.

An eLearning module is comparable to face-to-face teaching in a nursing human pathophysiology subject.

BACKGROUND: Human pathophysiology is important in undergraduate nursing education to help students develop clinical reasoning skills. Traditionally pathophysiology education in undergraduate nursing is taught face-to-face. However, eLearning in nursing curricula may provide flexible delivery options. OBJECTIVE: With increased inclusion of technology enhanced learning in nursing curricula, a hematology eLearning module was evaluated in a pathophysiology subject to determine whether it was comparable to face-to-face learning. DESIGN: Single-blind randomized pre-test/post-test controlled trial. SETTING: School of Health and Behavioural Sciences, University of the Sunshine Coast. PARTICIPANTS: A total of 271 second-year undergraduate students enrolled in Human Pathophysiology were included in the study. Students were from three bachelor programs: Nursing Science; Paramedic Science; and Clinical Exercise Physiology. Students were randomly allocated to either the experimental group (n = 85) or the control group (n = 186). METHODS: A hematology eLearning module was designed to be self-directed and learner-centered, guided by constructivist learning theories for delivery in the human pathophysiology subject. The experimental "eLearning" group completed the module independently, and the control "face-to-face" group completed equivalent paper-based activities facilitated by a tutor. All students completed a pre-test assessment and two post-test assessments two weeks after the intervention and at the end of the subject. RESULTS: There was no significant difference in assessment scores between the experimental and control groups, or between nursing and other programs. CONCLUSION: eLearning was comparable to face-to-face teaching in this study. We recommend further research to strengthen the links between pathophysiology theory to clinical reasoning skills using eLearning.

A Comparative Study of the Adherent-Invasive Escherichia coli Population and Gut Microbiota of Healthy Vegans versus Omnivores.

Adherent-invasive Escherichia coli (AIEC) strains carry virulence genes (VGs) which are rarely found in strains other than E. coli. These strains are abundantly found in gut mucosa of patients with inflammatory bowel disease (IBD); however, it is not clear whether their prevalence in the gut is affected by the diet of the individual. Therefore, in this study, we compared the population structure of E. coli and the prevalence of AIEC as well as the composition of gut microbiota in fecal samples of healthy participants (n = 61) on either a vegan (n = 34) or omnivore (n = 27) diet to determine whether diet is associated with the presence of AIEC. From each participant, 28 colonies of E. coli were typed using Random Amplified Polymorphic DNA (RAPD)-PCR. A representative of each common type within an individual was tested for the presence of six AIEC-associated VGs. Whole genomic DNA of the gut microbiota was also analyzed for its diversity profiles, utilizing the V5-V6 region of the16S rRNA gene sequence. There were no significant differences in the abundance and diversity of E. coli between the two diet groups. The occurrence of AIEC-associated VGs was also similar among the two groups. However, the diversity of fecal microbiota in vegans was generally higher than omnivores, with Prevotella and Bacteroides dominant in both groups. Whilst 88 microbial taxa were present in both diet groups, 28 taxa were unique to vegans, compared to seven unique taxa in the omnivores. Our results indicate that a vegan diet may not affect the number and diversity of E. coli populations and AIEC prevalence compared to omnivores. The dominance of Prevotella and Bacteroides among omnivores might be accounted for the effect of diet in these groups.

Enterococci populations of a metropolitan river after an extreme flood event: prevalence, persistence and virulence determinants.

We investigated the prevalence, persistence and virulence determinants of enterococci populations in water samples collected over three rounds following an extreme flood event in a metropolitan river. Enterococci (n = 482) were typed using the high resolution biochemical fingerprinting method (PhP typing) and grouped into common (C) or single (S) biochemical phenotypes (BPTs). In all, 23 C-BPTs (72.6% of isolates) were found across the sites. A representative isolate of each C-BPT was identified to the species level and tested for the presence of seven virulence genes (VGs), biofilm formation and resistance to 14 antibiotics. The enterococci concentrations in samples collected during the first two rounds were above national recreational water guidelines. By round three, enterococci concentrations decreased significantly (P < 0.05). However, 11 C-BPTs (55.5% of isolates) persisted across all sampling rounds. E. casseliflavus and E. mundtii were the most common enterococci populations comprising of >57% of all isolates. Ten of the 11 most dominant C-BPTs were resistant to multiple antibiotics and harboured one or more VGs. The high prevalence of antibiotic resistance and VGs among enterococci isolates in this catchment not only provides them with niche advantages but also poses a risk to public health.

Assessing the population dynamics of Escherichia coli in a metropolitan river after an extreme flood event.

We investigated Escherichia coli populations in a metropolitan river after an extreme flood event. Between nine and 15 of the 23 selected sites along the river were sampled fortnightly over three rounds. In all, 307 E. coli were typed using the PhP typing method and were grouped into common (C) or single (S) biochemical phenotypes (BPTs). A representative from each of the 31 identified C-BPTs was tested for 58 virulence genes (VGs) associated with intestinal and extra-intestinal E. coli, resistance to 22 antibiotics, production of biofilm and cytotoxicity to Vero cells. The number of E. coli in the first sampling round was significantly (P < 0.01) higher than subsequent rounds, whereas the number of VGs was significantly (P < 0.05) higher in isolates from the last sampling round when compared to previous rounds. Comparison of the C-BPTs with an existing database from wastewater treatment plants (WWTPs) in the same catchment showed that 40.6% of the river isolates were identical to the WWTP isolates. The relatively high number of VGs and antibiotic resistance among the C-BPTs suggests possessing and retaining these genes may provide niche advantages for those naturalised and/or persistent E. coli populations which may pose a health risk to the community.

The characteristics of genetically related Pseudomonas aeruginosa from diverse sources and their interaction with human cell lines.

We investigated a collection of Pseudomonas aeruginosa strains from hospitalised patients (n = 20) and various environmental sources (n = 214) for their genetic relatedness; virulence properties; antibiotic resistance; and interaction with intestinal (Caco-2), renal (A-498), and lung (Calu-3) cell lines. Using RAPD-PCR, we found high diversity among the strains irrespective of their sources, with only 6 common (C) types containing strains from both a clinical and environmental source. Environmental strains belonging to these C-types showed greater adhesion to A-498 cells than did clinical strains (17 ± 13 bacteria/cell versus 13 ± 11 bacteria/cell; p < 0.001), whereas clinical strains showed significantly greater adhesion to Calu-3 and Caco-2 cells than did environmental strains (p < 0.001 for both). The virulence genes and antibiotic resistance profiles of the strains were similar; however, the prevalence of environmental strains carrying both exoS and exoU was significantly (p < 0.0368) higher than clinical strains. While all strains were resistant to ticarcillin and ticarcillin-clavulanic acid, resistance against aztreonam, gentamicin, amikacin, piperacillin, and ceftazidime varied among environmental and clinical strains. These results suggest that environmental strains of P. aeruginosa carry virulence properties similar to clinical strains, including adhesion to various human cell lines, with some strains showing a higher adhesion to specific cell lines, indicating they may have a better ability to cause infection in those sites under predisposing conditions of the host.

First description of 'Chalky back' phenomenon in banana prawns (Fenneropenaeus merguiensis) and its possible association with Vibrio and Photobacterium species.

Here we report a newly identified 'Chalky back' phenomenon in banana prawns (Fenneropenaeus merguiensis) farmed in North Queensland, Australia. This was characterized by localized white discoloured segmentation of the cervical groove, moreover, after cooking the prawns exploded, making them unfit for commercial sale. Histological examination revealed breakdown of gut and abdominal muscle tissue in some moribund specimens. We selectively isolated Vibrio spp., which are known prawn pathogens, from healthy and Chalky back specimens. Isolated bacteria were identified, typed and tested for the presence of eight virulence genes (VGs), biofilm formation, adherence and cytotoxicity to fish cells. In all, 32 isolates were recovered and identified as Vibrio harveyi, V. owensii, V. sinaloensis-like, V. campbellii, V. shilonii, Vibrio sp. and Photobacterium damselae using 16S rRNA gene sequencing. All V. harveyi carried VGs coding for haemolysin, toxR and flagella; formed biofilm; and adhered to both cell lines. This was similar to the V. sinaloensis-like strains that were only isolated from Chalky back specimens. Our data suggest that Vibrio spp. may play a role in the pathogenesis of Chalky back. This study is the first report of Chalky back phenomenon in farmed banana prawns that needs to be closely monitored by the industry.

Population dynamics of Vibrio and Pseudomonas species isolated from farmed Tasmanian Atlantic salmon (Salmo salar L.): a seasonal study.

Vibrio and Pseudomonas species have been shown to be part of the normal microbiota of Atlantic salmon (Salmo salar L.), with some strains causing disease in fish. The factors affecting their prevalence and persistence in the salmon gut, however, have not been well studied. In this study, we collected 340 Vibrio and 150 Pseudomonas isolates from the hindgut of farmed Tasmanian Atlantic salmon, fed with two commercially available diets. Samples were collected every 6-8 weeks between July 2011 and May 2012. Isolates from selective agar were initially identified using biochemical tests and confirmed using genus-specific primers and 16S ribosomal RNA (16S rRNA) sequencing. Random amplified polymorphic DNA (RAPD) PCR was used to type both Pseudomonas and Vibrio; the latter was further typed using a biochemical fingerprinting method (PhP-RV plates). We observed low species diversity with strains comprising Vibrio ichthyoenteri/Vibrio scophthalmi, Vibrio crassostreae/Vibrio splendidus, Aliivibrio finisterrensis, Photobacterium phosphoreum and Pseudomonas fragi. Out of 340 Vibrio isolates, 238 (70 %) belonged to 21 clonal types and were found predominantly during summer when water temperatures reached 15 to 21 °C. Of these, the four major clonal types were found in multiple samples (70 %). P. fragi, on the other hand, was only found during the colder water temperatures and belonged to 18 clonal types. The presence of both groups of bacteria and their clonal types were independent of the fish diets used, suggesting that the water temperature was the main factor of the prevalence and persistence of these bacteria in the gut of Atlantic salmon.