Aims:  In this study, we examined the biofilm formation of 75 Salmonella enterica serovar Typhimurium (Salm. Typhimurium) human clinical isolates and the effect of subinhibitory concentrations (sub‐MICs) of gentamicin, ciprofloxacin and cefotaxime on biofilm formation and exopolysaccharides (EPS) production. Methods and Results:  Quantification of biofilm formation and EPS production were carried out using a modified microtitre plate assay and spectrophotometric method, respectively. The results indicate that 38 isolates (50·7%), which are predominantly of DT104 phage type, presented as the strong biofilm producers in vitro on plastic surface. When strains with the highest biofilm‐forming capacity were grown in the presence of sub‐MICs of gentamicin and ciprofloxacin, the inhibition of biofilm formation and EPS production was observed. In contrast, cefotaxime at 1/2 MIC (0·039 μg ml−1) was able to significantly induce the production of biofilm as well as EPS in three isolates with nontypable and DT104 phage type, respectively. Conclusions:  These results clearly indicate that all the three antibiotics tested are able to interfere with biofilm formation and EPS production by Salm. Typhimurium isolates. Significance and Impact of the Study:  The current study demonstrated that cefotaxime at sub‐MIC can be beneficial for the behaviour of pathogen Salm. Typhimurium in vitro.

International audienceMulti-drug resistance in nosocomial pathogens is a continually evolving and alarming problem in health care units. Since ancient times, honey has been used successfully for treatment of broad spectrum of infections with no risk of resistance development. In this study, we investigated the antibacterial activity of two natural honeys, namely honeydew and manuka, against 20 nosocomial multi-drug resistant Stenotrophomonas maltophilia (S. maltophilia) isolates from cancer patients. Antibiotic susceptibility test was carried out using disk diffusion method with 20 antibiotic disks. The antibacterial activity of honey was determined using a broth dilution method. The concentration of honey used in study was within the range of 3.75% to 25% (w/v). All 20 clinical isolates were multi-drug resistant against 11 to 19 antibiotics. The MICs for honeydew honey ranged from 6.25% to 17.5%, while those for active manuka honey ranged from 7.5% to 22.5%. Honeydew honey had the lower MICs than manuka honey against 16 of tested isolates. This study showed that Slovak honeydew honey has exceptional antibacterial activity against multi-drug resistant S. maltophilia isolates and was more efficient than manuka honey (UMF 15+). Honeydew honey with strong antibacterial activity could be used as a potential agent to eradicate of multi-drug resistance clinical isolates

Salmonella isolates were quickly and thoroughly characterized by a novel oligonucleotide microarray, which could become a useful tool for detection of virulence and resistance genes and monitoring of their dissemination among salmonellae and closely related bacteria.

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