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2 results on '"Larion C"'

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

Author

Chifiriuc MC, Israil AM, Larion C, Alexandru I, and Dobre G

Subjects
Adult, Aeromonas classification, Aeromonas isolation & purification, Bacterial Proteins genetics, Bacterial Proteins metabolism, Bacterial Typing Techniques, Child, Child, Preschool, Cold Temperature, Diarrhea microbiology, Gram-Negative Bacterial Infections epidemiology, Gram-Negative Bacterial Infections microbiology, Humans, Infant, Microbial Sensitivity Tests, Phenotype, Polysaccharide-Lyases genetics, Polysaccharide-Lyases metabolism, Romania epidemiology, Seasons, Temperature, Virulence, Virulence Factors metabolism, Aeromonas drug effects, Aeromonas pathogenicity, Anti-Bacterial Agents pharmacology, Diarrhea epidemiology, Drug Resistance, Bacterial genetics, Fresh Water microbiology, Virulence Factors genetics
Abstract

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. 28 degrees C and 37 degrees C) for all strains. Mucinase was the unique virulence factor constantly present in all three categories of strains at all three incubation temperatures. The aquatic as well as clinical strains exhibited similar R levels to ampicillin and colistin, while for the other tested antibiotics, the aquatic strains generally proved higher R levels than clinical strains, excepting cephtazidime. Plasmids of molecular weights ranging between 1904-21226 bp, were isolated in 36.5% of Aeromonas strains, some of them being correlated with specific R patterns. The large virulence spectrum correlated with high R in Aeromonas strains isolated from the aquatic medium is pleading for the significant role of these bacteria in the pathogenic potential of the natural reservoir possibly implicated in human pathology.

Published
2007

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

Author

Drǎcea, O., Iordache, C., Bucur, M., Bleotu, C., Banu, O., Ungureanu, C., Cristea, D., Lixandru, M. S., Larion, C., Necula, G., Lazǎr, V., and Mariana Carmen Chifiriuc

Subjects
Imipenem, Nalidixic Acid, Chemical Phenomena, Biofilms, Ceftriaxone, Drug Resistance, Bacterial, Escherichia coli, Cefotaxime, Microbial Sensitivity Tests, beta-Lactams, Anti-Bacterial Agents, Culture Media
Abstract

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. Our results demonstrated that the inhibition diameter zone was much larger on PCA, EMB and MC than on MH, considered as general standard medium for the antibiosusceptibility testings (CLSI). When bacterial cells were included in the agar matrix, the growth inhibition diameters obtained for different beta-lactams proved to be different of planktonic cells, i.e.: for CTX, a narrow inhibition diameter was obtained, demonstrating the low efficiency of this antibiotic in the treatment of biofilm associated infections, whereas the CRO proved the same efficiency against planktonic as well as to agar embedded bacteria. The different susceptibility results obtained for the cells embedded in the agar matrix by an adapted disk diffusion method are pleading for the necessity to assess new adapted standard methods and specific parameters in the purpose to determine the antibiotic resistance of bacterial cells isolated from biofilm associated infections.

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