Vibrio (V.) cholerae forms a pellicle for self-defense in the pathological conditions in the intestine, which protects it against antibiotics and adverse conditions. Targeting biofilm genes and Toll-like receptors (TLRs) is one of the new strategies to combat multidrug-resistant bacteria. The objective of this study was to evaluate the effect of mesenchymal stem cell conditioned media (MSC CM; 1000 µg), chitosan nanoparticles incorporated with mesenchymal stem cell conditioned media (MSC CM-CS NPs; 1000 µg + 0.05%), and chitosan nanoparticles (CS NPs; 0.05%) on the expression of bap1 and rbmC biofilm genes in V. cholerae and TLR2 and TLR4 genes in Caco-2 cells. The bacteria were inoculated in the presence or absence of MSC CM, MSC CM-CS NPs, and CS NPs for 24 h at 37 °C to evaluate the expression of biofilm genes. The Caco-2 cells were also exposed to V. cholerae for 1 h and then MSC CM, MSC CM-CS NPs, and CS NPs for 18 h at 37 °C. After these times, RNA was extracted from Caco-2 cells and bacteria exposed to the compounds, and the expression of target genes was evaluated using real-time PCR. Caco-2 cell viability was also assessed by MTT assay. After adding MSC CM, MSC CM-CS NPs, and CS NPs to V. cholerae medium, the percentage reduction in gene expression of bap1 was 96, 91, and 39%, and rbmC was 93, 92, and 32%, respectively. After adding MSC CM, MSC CM-CS NPs, and CS NPs to the Caco-2 cell medium, the percentage reduction in the gene expression of TLR4 was 89, 90, and 82%, and TLR2 was 41, 43, and 32%, respectively. MTT showed that Caco-2 cell viability was high and the compounds had little toxicity on these cells. Finally, it suggests that MSC CM-CS NPs designed may be a therapeutic agent to combat inflammation and biofilm formation in multidrug-resistant V. cholerae. However, further studies in vivo are also recommended.

Background and Objectives: Vibrio fluvialis is a Gram-negative, bacillus-shaped, curved bacterium known as an emerging pathogen. There are reports ofoutbreaks caused by this bacterium worldwide. Iran, especially Qom province, is an endemic region for gastrointestinal diseases caused by Vibrio species. So,the aim was to isolate V. fluvialis from clinical and environ- mental samples. Materials and Methods: During six months, 363 clinical and surface water samples were evaluated. The samples were cultured on specific media, and allincubated for 24 hours at 37°C. Suspicious colonies were evaluated by Gram staining and biochemical tests. The BD Phoenix automated microbiologysystem was used for the final confirmation of the isolated bacteria. Evaluation of antibiotic resistance of isolated strains was also performed according to CLSI standard. Results: Eight cases (2.2%) of V. fluvialis, including seven from surface water samples (87.5%) and one from clinical sam- ples (12.5%), were isolated. Basedon antimicrobial susceptibility testing, all V. fluvialis isolates were susceptible to amika- cin, gentamicin, trimethoprim/sulfamethoxazole, ciprofloxacin,tetracycline, ceftazidime, and chloramphenicol. High-level resistance to ampicillin and amoxicillin/clavulanate was also observed. V. fluvialis-infected patienthad a mild fever, watery diarrhea, vomiting, nausea, and abdominal cramps that were manifested after drinking contaminated water or eating con- taminated vegetables. The patient's symptoms recovered without antibiotic therapy after four days, resulting in self-limiting disease. Conclusion: The current study is the first human case of V. fluvialis infection isolated in Iran. Therefore, monitoring of water and food samples should be done routinely.