Detection of antiseptic resistance genes among Staphylococcus aureus colonising nurses and coagulase-negative staphylococci isolated from clinical specimens at teaching hospitals in southwest of Iran

Background: The wide application of antibiotics and antiseptics for patient therapy and medical equipment and surfaces disinfection has resulted in the emergence of resistant microorganisms. Staphylococcus aureus and coagulase-negative Staphylococci (CoNS) are found as a part of the normal resident flora in human so that up to two-thirds of the healthy populations are permanently or transiently colonized by S. aureus and CoNS. Chlorhexidine is an antiseptic agent particularly effective against Gram-positive bacteria. It is widely used for hygienic hand wash to prevent transmission of Staphylococci nosocomial infections. The plasmid-borne qacA/B, qacC, and smr genes confer resistance to cationic antiseptic agents in S. aureus and CoNS. Objectives: The objective of the current study was to characterize the antibiotic resistance and susceptibility to quaternary ammonium compounds (QACs) in methicillin-sensitive S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), methicillin-sensitive coagulase-negative staphylococci (MSCoNS), and methicillin-resistant coagulase-negative Staphylococci (MRCoNS). Methods: In this study, the antibiotic susceptibility and resistance to Chlorhexidine in 120 Staphylococcal strains were evaluated by disc diffusion and Minimum inhibitory concentration (MIC) of Chlorhexidine gluconate (CHG) methods, respectively. The MICs of CHG were determined in triplicate by broth micro-dilution, and the presence of mecA, qacA/B, qacC, and smr genes was examined by PCR assay. Results: Of total 60 S. aureus isolates, 51 (85%) were MRSA, and of 60 CoNS, 7 (11.66%) were MRCoNS. The results showed that the MIC of Chlorhexidine for all 120 isolates was 1-16 _g/mL. 15 (12.5%) isolates carried qacA/B gene, 26 (21.7%) carried qacC gene, and 38 (31.7%) carried smr gene. Conclusions: Maintenance of MRSA isolates in the attendance of low amounts of antiseptics could result in the decreased susceptibility to antiseptics

Deletion of Salmonella enterica serovar typhimurium sipC gene

Objective: To construct a novel plasmid as Salmonella enterica serovar typhimurium (S. typhimurium) sipC gene knockouts candidate. Methods: In this research, 5′ upstream and 3′ downstream regions of S. typhimurium sipC gene and kanamycin gene were PCR amplified. Each of these DNA fragment was cloned into pGEM T-easy vector. The construct was confirmed by PCR and restriction digest. Results: PCR amplified 320, 206 and 835 bp DNA fragments were subcloned into pET-32 vector resulting with a plasmid called pET-32-sipC up-kan- sip C down. Conclusions: The new plasmid (pET-32-sipC up-kan- sip C down) is useful for genetic engineering and for future manipulation of S. typhimurium sipC gene

Integrative analysis of lncRNAs in kidney cancer to discover a new lncRNA (LINC00847) as a therapeutic target for staphylococcal enterotoxin tst gene

Objective: Bacterial toxin can cause cell death through induction of apoptosis in cancer cell lines as well as changes in the expression patterns of long non-coding RNAs (lncRNAs) and genes. In the present study, the effect of tst gene on ACHN cell lines was reported along with proposing a novel pathway of apoptosis in kidney cancer. Materials and Methods: In this experimental study, effective lncRNAs and genes were predicted from different criteria for renal cell carcinoma (RCC) by bioinformatics methods and lncRNA-miRNA-mRNA interaction was constructed; then the effect of Staphylococcus aureus tst gene on induction of apoptosis pathways on ACHN and HDF cell lines was investigated. Results: After creation of lncRNA-miRNA-mRNA interaction, changes in expression levels of lncRNA LINC00847 (P=0.0024) and PTEN gene (P=0.0027) were identified, as potential apoptosis biomarkers for kidney cancer, after treating ACHN cell line by pCDNA3.1 (+)-tst compared to the empty vector. In contrast, there was no statistically significant difference in DICER1 expression levels in ACHN-tst cell (P≥0.05). In addition, transfection by pcDNA3.1 (+)-tst could increase ACHN cell apoptosis level (P<0.0001) compared to the pcDNA3.1 (+) group; but no significant effect was observed on normal cells. Conclusion: It is suggested that lncRNA LINC00847, discovered in this study, could provide a new landscape for researches aimed to determine relationship between functional lncRNA and RCC pathways. pcDNA3.1 (+)-tst was found to increase apoptosis in the transfected cell