Prevalence of Panton-valentine gene in Staphylococcus aureus isolated from clinical samples and healthy carriers in Gorgan city, north of Iran

Aim. Staphylococcus aureus (S. aureus) is a nosocomial and community acquired pathogen. S. aureus is a pathogen that causes several types of disease from skin infections to systemic diseases that is because of having several virulence factors such as enzymes, toxins, superantigens and Panton-Valentine leukocidin (pvl). pvl is a bi-component leukotoxin that destroy PMNs and monocytes and causes furunculosis, abscesses and necrotizing soft tissue infections in patients without any risk factors for such infections. The goal of this study was determine the prevalence of pvl gene in S. aureus isolated from patients and healthy carriers in Gorgan city, north of Iran. Methods. One hundred seventy isolates of S. aureus, 95 from patients and 75 healthy carriers, were collected during one year. After identification and purification, DNA extraction was done by phenol-chloroform method. Amplification of pvl gene was done by specific primer and polymerase chain reaction method. Results. Among the 170 isolates of S. aureus, 20 contained pvl gene. The frequency of isolates contained pvl gene in MRSA and MSSA isolates were 21.6, 19.3, which was not statistically significant. The frequency of these genes was not related to age, sex and source of isolation from patients. Conclusion. The frequency of pvl gene in this region were much higher than expected. © Copyright 2016 Edizioni Minerva Medica

The comparison of biochemical and sequencing 16S rDNA gene methods to identify nontuberculous Mycobacteria

The identification of Mycobacteria in the species level has great medical importance. Biochemical tests are laborious and time-consuming, so new techniques could be used to identify the species. This research aimed to the comparison of biochemical and sequencing 16S rDNA gene methods to identify nontuberculous Mycobacteria in patients suspected to tuberculosis in Golestan province which is the most prevalent region of tuberculosis in Iran. Among 3336 patients suspected to tuberculosis referred to hospitals and health care centres in Golestan province during 2010-2011, 319 (9.56%) culture positive cases were collected. Identification of species by using biochemical tests was done. On the samples recognized as nontuberculous Mycobacteria, after DNA extraction by boiling, 16S rDNA PCR was done and their sequencing were identified by NCBI BLAST. Of the 319 positive samples in Golestan Province, 300 cases were M.tuberculosis and 19 cases (5.01%) were identified as nontuberculous Mycobacteria by biochemical tests. 15 out of 19 nontuberculous Mycobacteria were identified by PCR and sequencing method as similar by biochemical methods (similarity rate: 78.9%). But after PCR, 1 case known as M.simiae by biochemical test was identified as M. lentiflavum and 3 other cases were identified as Nocardia. Biochemical methods corresponded to the 16S rDNA PCR and sequencing in 78.9% of cases. However, in identification of M. lentiflavum and Nocaria sp. the molecular method is better than biochemical methods. © 2014 by Razi Vaccine & Serum Research Institute

The Comparison of Biochemical and Sequencing 16S rDNA Gene Methods to Identify Nontuberculous Mycobacteria

ABSTRACT The identification of Mycobacteria in the species level has great medical importance. Biochemical tests are laborious and time-consuming, so new techniques could be used to identify the species. This research aimed to the comparison of biochemical and sequencing 16S rDNA gene methods to identify nontuberculous Mycobacteria in patients suspected to tuberculosis in Golestan province which is the most prevalent region of tuberculosis in Iran. Among 3336 patients suspected to tuberculosis referred to hospitals and health care centres in Golestan province during 2010-2011, 319 (9.56%) culture positive cases were collected. Identification of species by using biochemical tests was done. On the samples recognized as nontuberculous Mycobacteria, after DNA extraction by boiling, 16S rDNA PCR was done and their sequencing were identified by NCBI BLAST. Of the 319 positive samples in Golestan Province, 300 cases were M.tuberculosis and 19 cases (5.01%) were identified as nontuberculous Mycobacteria by biochemical tests. 15 out of 19 nontuberculous Mycobacteria were identified by PCR and sequencing method as similar by biochemical methods (similarity rate: 78.9%). But after PCR, 1 case known as M.simiae by biochemical test was identified as M. lentiflavum and 3 other cases were identified as Nocardia. Biochemical methods corresponded to the 16S rDNA PCR and sequencing in 78.9% of cases. However, in identification of M. lentiflavum and Nocaria sp. the molecular method is better than biochemical methods