Antibiotic resistance and frequency of class 1 integrons among Pseudomonas aeruginosa isolates obtained from wastewaters of a burn center in Northern Iran.

BACKGROUND: Pseudomonas aeruginosa, being responsible of a broad variety of infections, is considered an important nosocomial pathogen. The emergence of multiple-drug resistance among strains of P. aeruginosa appeared as a further public health concern. Due to the considerable ability of multiple-drug resistant P. aeruginosa strains to transmit themselves in the environment, we aimed to investigate the association of class 1 integrons with the antibiotic resistance profile of P. aeruginosa strains isolated from hospital wastewaters. METHODS: In this cross-sectional study, a total of 100 P. aeruginosa isolates were obtained from raw wastewater samples from February 2010 to January 2011 in a Teaching Burn Hospital in Guilan province. All isolates were identified as P. aeruginosa using standard microbiological tests. Antibiotic susceptibility was investigated using the disk diffusion method according to Clinical and Laboratory Standards Institute recommendations. All isolates were assayed for the presence of the class 1 integrons gene by PCR. RESULTS: Overall, 30 (30%) P. aeruginosa isolates were positive for the presence of class 1 integrons. The highest antibiotic resistance rates in both integron-positive and -negative isolates belonged to cephalexin and cephazolin, with 100% resistance. Amikacin and ciprofloxacin with the lowest level of resistance (13.3%) were the effective antibiotics against integron-positive isolates. The rates of MDR isolates were significantly higher among integron-positive isolates with 43.3% compared to negative isolates with 22.9% (P < 0.05). CONCLUSION: The results highlight the importance of class 1 integrons in multiple antibiotic resistance among P. aeruginosa isolates. Moreover, the spread of hospital derived wastewaters in the environment can be regarded as the origin of significant reservoirs for antibiotic-resistant pathogens.

Role of Wnt signaling on proliferation of menstrual blood derived stem cells.

AIM: Menstrual blood derived stem cells (MenSCs) are unique stem cells that have been isolated and identified recently. The special traits of MenSCs can be related to the cell signaling pathways. In this study, in order to find out the role of Wnt signaling on MenSCs proliferation, we evaluated ß-catenin expression as a key participant in Wnt signaling pathway in response to Lithium chloride (LiCl). METHODS: MenSCs were isolated from healthy women by combining gradient density centrifugation with plastic adherence. After characterization of the isolated cells, cell proliferation of MenSCs in presence of 10-15 mM LiCl was evaluated by MTT assay. ß-catenin expression of the treated cells was examined using immunofluorescence technique. RESULTS: Flow cytometric analysis revealed that both mesenchymal and embryonic stem cell markers are expressed on menstrual blood stem cells. MTT value decreased depending on the LiCl concentration. The proliferation of MenSCs cultivated in culture media containing 15mM LiCl was approximately two fold less than those grown without LiCl (p<0.01). Moreover, nuclear accumulation of ß-catenin protein in cells treated by LiCl was greater than cells without LiCl. CONCLUSION: The MenSCs are stem cell populations with high proliferation ability and unique immunophenotyping properties. Our results demonstrated that Wnt signaling pathway regulates MenSCs proliferation via trans-localization of activated-ß-catenin protein.