1,720,977 research outputs found
Analysis of genetic variability, antimicrobial susceptibility and virulence markers in Helicobacter pylori identified in Central Italy.
No full textObjective. To assess the relationship between the presence of mixed infection of Helicobacter pylori and both antimicrobial susceptibility and virulence markers. Material and methods. Thirty-six patients with H. pylori infection were included in the study. Three colonies were selected from each positive biopsy sample collected from each host for a total of 108 H. pylori strains. The genetic variability was evaluated through the amplified fragment length polymorphism (AFLP) analysis; the antibiotic susceptibility to amoxicillin, clarithromycin, moxifloxacin, rifabutin and tinidazole was determined using the minimum inhibitory concentrations (MICs) with the agar dilution method. Moreover, the vac A, cag A, iceA and bab A2 status were detected by polymerase chain reaction (PCR). Results. There was a strong connection between mixed H. pylori infection and antimicrobial resistance. In particular, H. pylori strains with genetic variability, in the same host, expressed more resistance to clarithromycin, moxifloxacin and tinidazole than that expressed in strains with a unique genetic host pattern. Vac A s1m1/s1m2 genotypes were found in 70% of strains isolated in mixed infection, whereas the same allelic combinations were found in 42% of strains, isolated in single infection. The cag A+status prevailed both in patients with mixed (97%) and in those with single infection (85%) without significant differences. The ice A1 status was more commonly found in patients with mixed infection, whereas the bab A2 status was significantly prevalent in single H. pylori infection. Conclusions. Mixed H. pylori infection harbouring in one patient is significantly related to strains that are
more resistant to antibiotics and with a more virulent genotype (vac A s1m1/s1m2, cag A, ice A1) than strains responsible for single infection
Bovine lactoferrin enhances the efficacy of levofloxacin-based triple therapy as first-line treatment of Helicobacter pylori infection: an in vitro and in vivo study.
No full textOBJECTIVES: To evaluate the in vitro antimicrobial/antivirulence action of bovine lactoferrin and its ability to synergize with levofloxacin against resistant Helicobacter pylori strains and to analyse the effect of levofloxacin, amoxicillin and esomeprazole with and without bovine lactoferrin as the first-line treatment for H. pylori infection. METHODS: The bovine lactoferrin antimicrobial/antivirulence effect was analysed in vitro by MIC/MBC determination and twitching motility against six clinical H. pylori strains and a reference strain. The synergism was evaluated using the chequerboard assay. The prospective therapeutic trial was carried out on two separate patient groups, one treated with esomeprazole/amoxicillin/levofloxacin and the other with esomeprazole/amoxicillin/levofloxacin/bovine lactoferrin. Treatment outcome was determined with the [13C]urea breath test. RESULTS: In vitro, bovine lactoferrin inhibited the growth of 50% of strains at 10 mg/mL and expressed 50% bactericidal effect at 40 mg/mL. The combination of levofloxacin and bovine lactoferrin displayed a synergistic effect for all strains, with the best MIC reduction of 16- and 32-fold for levofloxacin and bovine lactoferrin, respectively. Bovine lactoferrin at one-fourth MIC reduced microbial motility significantly for all strains studied. In the in vivo study, 6 of 24 patients recruited had treatment failure recorded with esomeprazole/amoxicillin/levofloxacin (75% success, 95% CI 57.68%-92.32%), and in the group with esomeprazole/amoxicillin/levofloxacin/bovine lactoferrin, 2 out of 53 patients recruited had failure recorded (96.07% success, 95% CI 90.62%-101.38%)
Bio-Toxicological Assay to Test Water and Sediment Quality.
No full textThis study assessed the bio-toxicological assays efficacy in the control of effluent waters deriving from purification plants, such as industrial or wastewater discharge and marine sediment collected from the Adriatic sea on the Italian Coast. The analysis was performed using either Acute Toxicity Test containing bioluminescent bacteria or Algal Growth Inhibitory Test (used on sediments only). Furthermore, samples were also characterized by microbiological parameters to search for indicators of faecal contamination. From the 29 samples collected from effluent waters, 6 showed an inhibition of bacterial luminescence higher than 20% and the analysis of EC50 expressed a strong toxicity for 4 of them, whereas 9 of the remaining 23 samples exhibited a bioluminescence stimulation defined as “hormesi”. No samples of marine sediments displayed a reduction of luminescence exceeding 20% with respect to the control. Toxicity tests can represent efficacious tools to detect the presence of pollutants for the preservation of the aquatic system and human health
The bacterial anti-adhesive activity of double-etched titanium (Dae) as a dental implant surface
Full text linkThis work aimed to compare the capability of Streptococcus oralis to adhere to a novel surface, double-etched titanium (DAE), in respect to machined and single-etched titanium. The secondary outcome was to establish which topographical features could affect the interaction between the implant surface and bacteria. The samples’ superficial features were characterized using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS), and the wetting properties were tested through sessile methods. The novel surface, the double-etched titanium (DAE), was also analyzed with atomic force microscopy (AFM). S. oralis was inoculated on discs previously incubated in saliva, and then the colony-forming units (CFUs), biomass, and cellular viability were measured at 24 and 48h. SEM observation showed that DAE was characterized by higher porosity and Oxygen (%) in the superficial layer and the measurement of the wetting properties showed higher hydrophilicity. AFM confirmed the presence of a higher superficial nano-roughness. Microbiological analysis showed that DAE discs, coated by pellicle’s proteins, were characterized by significantly lower CFUs at 24 and 48 h with respect to the other two groups. In particular, a significant inverse relationship was shown between the CFUs at 48 h and the values of the wetted area and a direct correlation with the water contact angle. The biomass at 24 h was slightly lower on DAE, but results were not significant concerning the other groups, both at 24 and 48 h. The DAE treatment not only modifies the superficial topography and increased hydrophilicity, but it also increases the Oxygen percentage in the superficial layer, which could contribute to the inhibition of S. oralis adhesion. DAE can be considered a promising treatment for titanium implants to counteract a colonization pioneer microorganism, such as S. oralis
Graphene Oxide affects Staphylococcus aureus and Pseudomonas aeruginosa dual species biofilm in Lubbock Chronic Wound Biofilm model
Full text linkChronic wound management becomes a complex procedure because of the persistence of forming biofilm pathogens that do not respond to antimicrobial treatment. The aim of this paper is to detect the Graphene Oxide-GO effect on Staphylococcus aureus and Pseudomonas aeruginosa dual species wound biofilm in Lubbock Chronic Wound Biofilm-LCWB model. LCWB is a recognized model that mimics the spatial microbial colonization into chronic wounds and reproduces the wound and its clot. Staphylococcus aureus PECHA 10 and P. aeruginosa PECHA 4, are the pathogens used in the study. The GO effect on both in forming and mature biofilms, is detected by the evaluation of the CFU/mg reduction, the cell viability and ultrastructural analysis of the treated LCWBs. Graphene Oxide, at 50 mg/l, shows a significant antibiofilm effect in forming and mature LCWBs. In particular, during the biofilm formation, GO reduces the S. aureus and P. aeruginosa growth of 55.05% ± 4.73 and 44.18% ± 3.91 compared to the control. In mature biofilm, GO affects S. aureus and P. aeruginosa by reducing their growth of 70.24% ± 4.47 and 63.68% ± 17.56, respectively. Images taken by SEM show that GO display a disaggregated microbial effect also disrupting the fibrin network of the wound-like biofilm framework. In conclusion, GO used against microorganisms grown in LCWB, displays a significant inhibitory action resulting in a promising tool for potential application in wound management
Biofilm formation and modulation of luxS and rpoD expression by Helicobacter pylori.
No full textBacteria often choose a sessile biofilm lifestyle as a strategy to overcome environmental
stress. In this study, we describe biofilm formation by Helicobacter
pylori on a polystyrene surface, evaluating the viability and the morphological
dynamics of bacterial cells during multicellular aggregate development.
Moreover, we investigate expression of the luxS and rpoD genes, which are
involved in biofilm formation.
Two clinically susceptible and resistant strains of H. pylori were analyzed,
as well as H. pylori ATCC 43629 for reference. The dominant form of expression,
clustered bacterial cells arranged in an abundant matrix, was recorded
after 2 days of incubation without shaking. Coccoid (spherical) cells with a
“wrinkled” aspect presented the prevalent morphology (59.26%) among cells
in the biofilm structure as observed by scanning electron microscopy. In aged
H. pylori cultures, death occurred in single cells or cells grouped into microcolonies
in which degenerated bacteria were localized inside the aggregates.
The expression of luxS and rpoD genes among the sessile bacterial population
reached a maximum after 2 days, with a significant reduction at subsequent
time-points. No differences in gene expression and biofilm formation were
recorded in the three evaluated strains.
The morphological fickleness expressed in the life cycle by H. pylori strains
emphasizes the bacterium’s ability to overcome environmental stress, balancing
its spread both outside and inside the host
The effect of oxygen on the growth and cell morphology of Helicobacter pylori.
No full textThe in vitro effect of progressive oxygen decrease on the growth and morphology of Helicobacter pylori was studied. H. pylori ATCC 43,504 was used for the experiments. The strain inoculated in Brucella broth plus fetal calf serum was incubated under a controlled atmosphere with oxygen concentration from 5 to 0%. CFU ml-1 and bacterial morphology were detected at the time of spreading and at 24 h, 72 h, 7 days and 14 days. A detailed ultrastructural investigation of the bacterial cells, grown in different experimental conditions, was performed by scanning electron microscopy. Oxygen deprivation produced a rapid reduction of CFU ml-1. In particular, a significant reduction of viable bacteria was recorded at 72 h of incubation in the presence of 1% oxygen and anaerobiosis, and 0 CFU ml-1 was found after 7 days of incubation at the above mentioned oxygen concentrations. The coccoid phenotype was already prevalent after 24 h of incubation with a progressive tendency to aggregate in clusters. These clusters were progressively larger, depending on the reduction of oxygen concentration, since the aggregation phenomenon can be the expression of a hypothesized mechanism of protection among bacterial cells
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