Screening of molecular virulence markers in Staphylococcus aureus and Pseudomonas aeruginosa strains isolated from clinical infections.

Staphylococcus (S.) aureus and Pseudomonas (Ps.) aeruginosa are two of the most frequently opportunistic pathogens isolated in nosocomial infections, responsible for severe infections in immunocompromised hosts.

Investigation of the influence of different physico-chemical parameters upon the susceptibility of planktonic and adherent Escherichia coli cells to beta-lactams and quinolones.

The purpose of this study was to evaluate the influence of different physico-chemical parameters on Escherichia coli susceptibility to ceftriaxone (CRO), cefotaxime (CTX), imipenem (IMP), and nalidixic acid (as marker for resistance by impermeability). The influence of chemical composition of culture medium was evaluated by the comparative assessment of inhibition growth diameters on different solid media: Mueller Hinton Medium (MH), Plate Count Agar Medium (PCA), MacConkey Medium (MC) and Eosin Methylen Blue Medium (EMB). In order to evaluate the differences in antibiotic susceptibility between the biofilm embedded and planktonic cells, an original, simple experimental model was used, by including the bacterial cells in an agar layer, mimicking the biofilm matrix.

Comparative study of pathogenicity tests for Shigella spp. and enteroinvasive Escherichia coli strains.

The purpose of this study was to optimize an in vitro pathogenicity model, as an alternative to Sereny test (on Guinea pigs). The study was performed on 13 Shigella spp. and 3 enteroinvasive Escherichia coli (EIEC) strains isolated in Romania between 2005 and 2007.

In vivo experimental model for the study of the influence of subinhibitory concentrations of phenyllactic acid on Staphylococcus aureus pathogenicity.

The discovery of communication systems regulating bacterial virulence has afforded a novel opportunity to control infectious bacteria without interfering with their growth. In this paper the authors describe the effect of subinhibitory concentrations of phenyl-lactic acid (PLA) on the pathogenicity of Staphylococcus aureus in holoxenic mice. The animals were inoculated by oral (p.

Subinhibitory concentrations of phenyl lactic acid interfere with the expression of virulence factors in Staphylococcus aureus and Pseudomonas aeruginosa clinical strains.

The discovery of intra- and intercellular communication systems (quorum sensing systems) regulating bacterial virulence has afforded a novel opportunity to control infectious bacteria, without interfering with their growth. In this study, we investigated the ability of subinhibitory concentrations (sIC) of phenyl lactic acid (PLA), known to be produced by Lactobacillus probiotic strains, to attenuate the virulence and pathogenicity of Pseudomonas aeruginosa (as experimental model of intercellular bacterial communication in Gram-negative bacteria) and Staphylococcus aureus (as experimental model of intercellular bacterial communication in Gram-positive bacteria) by interfering with the coordinated expression of different virulence factors implicated in the pathogenicity of these opportunistic strains. Our results showed that sIC of PLA decreased the ability of the tested strains to adhere both to the cellular and inert substrata and induced changes in the adherence patterns as well as in the cell morphology.

New thioureides of 2-(4-methylphenoxymethyl) benzoic acid with antimicrobial activity.

The purpose of this study was to evaluate in vitro, by means of qualitative and quantative methods, the antimicrobial activity of some new synthesized chemical compounds previously solubilized in DMF (Dimethyl formamide). The qualitative screening of the susceptibility spectra of different microbial strains versus these compounds was performed by three adaptated diffusion methods: paper filter disk impregnation with the tested substances solutions, the disposal of tested solutions in agar wells and the spotting of tested solutions on solid medium previously inoculated with microbial suspension. The quantitative assay of the antimicrobial activity was performed by broth microdilution method in 96-well microplates in order to establish the minimal inhibitory concentration (MIC).

The role of proteins expressed under the stress condition in virulence of some Vibrio strains.

In order to survive in changing environments, bacteria possess enormous adaptive capabilities that allow them to modulate their behavior and reprogram gene expression in response to environmental cues. Vibrios are inhabitants of estuarine and fresh waters and some species are pathogenic to humans, and marine vertebrates and invertebrates. Surface attachment is believed to be essential for colonization of all of these natural environments.

Thioureides of 2-(phenoxymethyl)benzoic acid 4-R substituted: a novel class of anti-parasitic compounds.

Fifty members of a novel class of antimicrobial compounds, 2-(4-R-phenoxymethyl)benzoic acid thioureides, were synthesized and characterized with respect to their activities against three parasites of human relevance, namely the protozoa Giardia lamblia and Toxoplasma gondii, and the larval (metacestode) stage of the tapeworm Echinococcus multilocularis. To determine the selective toxicity of these compounds, the human colon cancer cell line Caco2 and primary cultures of human foreskin fibroblasts (HFF) were also investigated. The new thioureides were obtained in a three-step-reaction process and subsequently characterized by their physical constants (melting point, solubility).

Virulence and resistance markers in clinical and environmental Aeromonas strains isolated in Romania.

The virulence and resistance (R) features of 37 Aeromonas strains from diarrheal cases and 150 from the aquatic environment (isolated during cold and warm season) were tested at different incubation temperatures (4 degrees C, 28 degrees C and 37 degrees C). When incubated at 4 degrees C temperature, the Aeromonasstrains isolated during the cold season expressed the highest number of virulence factors by comparison with the strains isolated during warm season and from diarrhoeal cases, the virulence spectrum increasing simultaneously with the incubation temperature (i.e.

Investigation of dental-plaque formers biofilms by optic and confocal laser scanning microscopy and microbiological tools.

The aim of the present study was to investigate the dental plaque formed on natural teeth surfaces by optic and confocal laser scanning microscopy (CLSM), to quantify the microbial density by viable cell counts, to identify the recovered microbial strains, the antibiotic susceptibility testing and their pathogenicity features (i.e. adherence and invasion capacity on HeLa cells, adherence on prostetic substrata used in oral medicine by original experimental models, production of extracellular enzymes and exotoxins).

Antimicrobial activity of some new thioureides derived from 2-(4-chlorophenoxymethyl)benzoic acid.

We report here the characterisation of eight newly synthesized thioureides of 2-(4-chlorophenoxymethyl)-benzoic acid and the evaluation of the in vitro antimicrobial activity of the new compounds against Gram-positive [Listeria monocytogenes,Staphylococcus aureus, Bacillus subtilis], Gram-negative [Psedomonas aeruginosa,Escherichia coli, Salmonella enteritidis], as well as Candida spp., using both reference and clinical multidrug resistant strains to establish the minimal inhibitory concentration (MIC)values. Our results showed that the tested compounds exhibited specific antimicrobial activities, both concerning the spectrum of antimicrobial activity and the corresponding MIC values, which ranged widely between 1024 and 32 mug/mL, depending on the nature and position of the substituents on the benzene ring.

Novel antipathogenic strategies against adherent enterobacterial strains isolated from the hospital environment.

The emergence of the bacterial antibiotic multi-resistance made more and more stringent the developing of new anti-microbial strategies. The purpose of the present study was to investigate the antimicrobial potential of six (6) newly synthesized chemical compounds (derivating from phenantroline and dimethylguanin-copper complex combinations) versus 97 enterobacterial strains isolated from the hospital environment. The qualitative screening of the antimicrobial activity of the chemical compounds was performed by an adapted diffusion method.