Phenotypic and genotypic evaluation of fluoroquinolone resistance in clinical isolates of Staphylococcus aureus in Tehran

Background: Fluoroquinolones are broad-spectrum antibiotics widely used in the treatment of bacterial infections such as Staphylococcus aureus isolates. Resistance to these antibiotics is increasing. Material/Methods: The occurrence of mutations in the grlA and gyrA loci were evaluated in 69 fluoroquinolone-resistant S. aureus isolates from 2 teaching hospitals of Tehran University of Medical Sciences. Results: Out of the 165 S. aureus isolates, 87 (52.7) were resistant to methicillin and 69 (41.8) were resistant to fluoroquinolone. Fluoroquinolone-resistant S. atoms isolates had a mutation at codon 80 in the grlA gene and different mutational combinations in the gyrA gene. These mutational combinations included 45 isolates at codons 84 and 86,23 isolates at codons 84,86 and 106 and 1 isolate at codons 84, 86 and 90. Fluoroquinolone-resistant S. aureus isolates were clustered into 33 PFGE types. Conclusions: The findings of this study show that the fluoroquinolone-resistant S. aureus strains isolated in the teaching hospitals in Tehran had multiple mutations in the QRDRs region of both grlA and gyrA genes

Characterization of Alloiococcus otitidis strains isolated from children with otitis media with effusion by Pulsed-Field Gel Electrophoresis

Objective: Alloiococcus otitidis is a slow growing organism which has been isolated in a few studies on patients with otitis media with effusion (OME). According to the literature review, there is no study about the molecular typing of A. otitidis. In this study, the characteristics of A. otitidis isolates from patients with OME were investigated via Pulsed-Field Gel Electrophoresis (PFGE) typing method. Methods: A total of 50 children with OME, who underwent myringotomy or who had an insertion of a ventilation tube, were included in this study. The isolates were identified to the species level as A. otitidis using standard biochemical methods, following which the amplification and sequencing of the 16S rRNA gene were carried out. The molecular characteristic of A. otitidis was investigated by PFGE technique. Results: Fifteen isolates of A. otitidis were identified in the middle ear fluid of the patients. All the isolates were susceptible to ampicillin, amoxicillin/clavulanate and fluoroquinolones. All of the 15 isolates were typed by PFGE method and were found to include 13 different PFGE types. Conclusion: The current study, being the first reports on the molecular typing of A. otitidis by PFGE method, shows that A. otitidis is a heterogenic organism in Iranian children who have OME. (C) 2012 Elsevier Ireland Ltd. All rights reserved

MOLECULAR ANALYSIS AND ANTIMICROBIAL SUSCEPTIBILITY OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS IN ONE OF THE HOSPITALS OF TEHRAN UNIVERSITY OF MEDICAL SCIENCES: HIGH PREVALENCE OF SEQUENCE TYPE 239 (ST239) CLONE

Methicillin-resistant Staphylococcus aureus (MRSA), particularly the multi-drug-resistant clones, is an increasing worldwide problem. The average incidence rate of MRSA in Tehran was found to be over 40. A total of 140 MRSA isolates obtained from patients attending a teaching hospital in Tehran, from May 2009 to December 2009, were included in this study. The antimicrobial susceptibility profile of MRSA isolates was determined by the agar disk diffusion method. Molecular analysis of MRSA strains was accomplished by Pulsed-Field Gel Electrophoresis (PFGE) and Multi-locus sequence typing (MLST). Detection of mecA gene was used to confirm resistance to methicillin among the MRSA isolates. All the MRSA isolates were susceptible to chloramphenicol, teicoplanin, tigecycline and vancomycin. All MRSA isolates were resistant to oxacillin, whilst 139 strains showed resistance against ciprofloxacin, erythromycin, gentamicin, tetracycline and trimethoprim-sulfamethoxazole. PFGE analysis of all the 140 MRSA isolates produced five distinct pulsotypes designated as pulsotypes A-E. Most of the isolates (n = 132) were clustered into pulsotype A. The most prevalent sequence type (ST) was ST 239 (pulsotype A) found in 82 (37/45) of the tested isolates. The second most prevalent type was ST 1238 (pulsotypes B, C and D) found in 15 (7/45) of the isolates. The remaining type, ST 8 (pulsotype E) was found in a single isolate. The results of this study indicated that the MRSA clone ST 239 was a major clone in the selected university hospital of Tehran and that it was widely spread among the different wards as well as all the age groups of patients