Potentialization of ß-lactams with colistin: in case of extended spectrum ß-lactamase producing Escherichia coli strains isolated from children with urinary infections.

Five strains producing extended-spectrum ß-lactamases (ESBL) bacteria, identified as Escherichia coli, were isolated from children with urinary infections hospitalized at Roubaix hospital in the north of France. The DNA genotypes of these non-nosocomial isolates were determined by Random Amplified Polymorphic DNA (RAPD) method. Further, their DNA plasmids content revealed the presence of two distinct plasmids for S1, S2, S3 and one plasmid for S4 and S5. The antibacterial susceptibility of these ESBL bacteria was tested mainly against antibiotics of ß-lactams family. The ESBL producing bacteria were resistant to ticarcillin and cefotaxime but the combination of these antibiotics with colistin has dropped the MIC of ticarcillin below its breakpoint (isolates S2, S3 and S4), and has almost reached the breakpoint for cefotaxime (isolate S2). Thus, kill curves analyses carried out with only isolates S1 and S2, strengthened the bactericidal activity of the combinations of colistin-ticarcillin and colistin-cefotaxime against ESBL E. coli. Indeed, reduction of 3 log10 colony count were observed after 24 h of incubation.

Probiotic potential of Enterococcus faecalis strains isolated from meconium.

107 bacterial isolates with Gram positive staining and negative catalase activity, presumably assumed as lactic acid bacteria, were isolated from samples of meconium of 6 donors at Roubaix hospital, in the north of France. All these bacterial isolates were identified by MALDI-TOF mass spectrometry as Enterococcus faecalis. However, only six isolates among which E. faecalis 14, E. faecalis 28, E. faecalis 90, E. faecalis 97, and E. faecalis 101 (obtained from donor 3), and E. faecalis 93 (obtained from donor 5) were active against some Gram-negative bacteria and Gram-positive bacteria , through production of lactic acid, and bacteriocin like inhibitory substances. The identification of these isolates was confirmed by 16rDNA sequencing and their genetic relatedness was established by REP-PCR and pulsed field gel electrophoresis methods. Importantly, the aforementioned antagonistic isolates were sensitive to various classes of antibiotics tested, exhibited high scores of coaggregation and hydrophobicity, and were not hemolytic. Taken together, these properties render these strains as potential candidates for probiotic applications.