Hospital clones of Panton-Valentine leukocidin-positive and methicillin-resistant Staphylococcus aureus circulating in the Tehran community.

OBJECTIVES: The emergence of Panton-Valentine leukocidin (PVL)-positive Staphylococcus aureus has become a serious challenge in hospital and community settings. Therefore, this study was designed to determine the molecular characteristics and genetic relationship of PVL-positive S. aureus. METHODS: A total of 116 S. aureus isolates were collected from outpatients and inpatients within 48 h after admission. For PVL-positive strains, antibiogram testing, toxin gene profile, agr grouping, SCCmec typing and genotyping by pulsed-field gel electrophoresis (PFGE) were performed. RESULTS: Of 116 isolates, 13 (11.2%) harboured the PVL gene, 5 isolates (38.4%) were methicillin-resistant S. aureus (MRSA) with agr group I and SCCmec III. Of these, four strains were hospital-associated MRSA (HA-MRSA) that moved to the community and one strain was atypical community-associated MRSA (CA-MRSA), with characteristics of being PVL-positive, susceptible to all tested antibiotics, including clindamycin, with SCCmec III. This was recovered from a burn patient less than 24 h after the patient's admission and fulfilled the Centers for Disease Control and Prevention (CDC) criteria for CA-MRSA, except for the type of SCCmec. High diversity was found among PVL-positive strains by PFGE. All PVL gene-positive strains had hly and psms genes, but the tsst-1 gene was found just in methicillin-susceptible S. aureus (MSSA). CONCLUSION: The results indicate that the distribution of the PVL gene in MSSA isolates was higher than in MRSA strains, and various PVL-positive resistant and virulent clones of HA-MRSA are circulating in the community. Therefore, implementing systematic surveillance is necessary for the evaluation of common PVL-positive S. aureus clones in the community.

Molecular Characterization of Community-Associated Methicillin-Resistant Staphylococcus aureus in Iranian Burn Patients.

BACKGROUND & OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) is reported as one of the important bacterial causes of burn wound infections. This study was carried out to investigate molecular characterization of community-associated MRSA (CA-MRSA) isolated from Iranian burn patients. METHODS: A total of 31 isolates of S. aureus were collected from the Motahari Burns Hospital (Tehran, Iran) in 2016. All isolates were collected from outpatients and inpatients within 48 hours of admission. The mecA, pvl, tsst-1, hla-α, and psmα genes detecting, SCCmec, agr and PFGE typing were done. RESULTS: A total of 13 (41.9%) isolates were cefoxitin-resistant and mecA-positive, which were considered as MRSA. The SCCmec typing MRSA strains revealed type II in 1 (7.7%), type III in 9 (69.2%), and other types in 3 isolates (23.7%) cases. The agr typing of all 31 isolates showed that 14 (45.2%), 1 (3.2%), 6 (19.4%), and 10 (32.3%) strains belonged to agr groups 1, 3, 4, and unknown type, respectively. The pvl, tsst-1, hla-α, and psmα genes were positive in 3 (9.7%), 4 (12.9%), 21 (67.7%), and 31 (100%) isolates, respectively. Considering the cut-off values of ≥50%, 3 groups of related isolates (cluster A1, B1, and C1) in PFGE study were observed. CONCLUSION: The MRSA strains of this study were initially isolated as Community-associated S. aureus (CA-MRSA); however molecular characterization showed that a significant proportion of them had hospital-associated MRSA (HA-MRSA) features. Therefore, it is likely that the HA-MRSA strains are spread among the community.

Adsorptive removal of noxious cadmium from aqueous solutions using poly urea-formaldehyde: A novel polymer adsorbent.

Cadmium is a heavy metal toxic that enters water resources through industrial, household, agricultural waste and non-sanitary landfill of urban and industrial wastes. Pollution of water resources by cadmium increases incidence of diseases including Itai-Itai, kidney disorders, cancer, chromosome effects and kidney tubular damages in low exposures. The aim of this study is to study the efficiency of a new poly urea-formaldehyde adsorbent in the removal cadmium ions from aqueous solutions. The effect of different variables such as initial pH, contact time, initial concentration of cadmium and test of real wastewater samples were evaluated. In addition, laboratory data of cadmium adsorption by urea-formaldehyde adsorbent were matched to Langmuir, Freundlich and Temkin isotherm models. The results of the study showed that maximum adsorption capacity obtained by Langmuir model was 76.3 mg/g at pH = 5.5. Laboratory adsorption data matched mostly by Freundlich isotherm model (R2 =0.999) which indicates that adsorption of cadmium ions on heterogenic surfaces of poly urea-formaldehyde happens by chemical adsorption mechanism. Generally, the results of the study showed that new poly urea-formaldehyde adsorbent can be efficiently used to remove highly concentrated cadmium ions from aqueous solutions.