Prophage Typing of Methicillin Resistant Staphylococcus aureus Isolated from a Tertiary Care Hospital in Tehran, Iran

Abstract

This study has highlighted the presence of bacteriophage types among MRSA isolates to show the high potential of these isolates to produce broad spectrum of virulence factors. Background:Staphylococcus aureus is a common cause of infections among humans and animals and it is known as a community-acquired and nosocomial pathogen. Most of the isolates contain lysogenic phages which are responsible for production of various virulence factors such as enterotoxins, staphylokinase, β-lysin, lipase, exfoliative toxin A and Pantone-vlaentine leukociden (PVL). All staphylococcus isolates are classified in 6 groups according to their sensitivity to 27 known lysogenic phages. Objectives: This study was performed to detect the presence of bacteriophage types and determine antibiotic resistance pattern of methicillin resistant S. aureus (MRSA) isolates obtained from a tertiary care hospital in Tehran, Iran from 2008 to 2010. Materials and Methods: A total of 968 S. aureus isolates were collected from a tertiary care hospital in Tehran, Iran and identified at the species level by PCR and biochemical tests. Susceptibility to 17 antibiotics was determined. Then oxacillin and vancomycin minimum inhibitory concentration (MIC) of the resistant isolates were determined. Multiplex-PCR was used to detect 6 classes of prophages. Results: Out of the 968 isolates 247 isolates were resistant to methicillin. Highest antibiotic resistance was seen to penicillin (100%), erythromycin (89.8%), kanamycin (89.4%), ciprofloxacin (88.6%) and tobramycin (87.4) respectively. None of the MRSA isolates showed resistance to vancomycin, synercid and linezolid. MIC results indicated that 46.1 and 4.4% of isolates with high (MIC ≥ 128 µg/ml) and low level (MIC ≥ 4 µg/ml) showed resistance to oxacillin, respectively. Four different phage types and eight patterns of prophages were detected. All MRSA isolates contained at least one prophage. Totally, 2.8, 69.2 and 27.9% contained 5, 4 and 3 different prophage types, respectively. Conclusions: High prevalence of different classes of prophages indicating the potential to carry a broad spectrum of virulence factors and high oxacillin resistance were found in the MRSA isolates. Detection of SGF phage in 100% of the isolates indicates the ability of these isolates to produce virulence factors.

Biofilm Producing Staphylococcus epidermidis Strains Isolated From Clinical Samples in Tehran, Iran

“…The prevalence of erythromycin-resistant strains was significantly lower in other studies (30)(31)(32). On the other hand, we found that 10 biofilm and non-biofilm-producing strains showed susceptibility to all tested antibiotics except for penicillin; these findings are consistent with our previous reports for S. aureus strains (17,(33)(34)(35)(36)(37)(38). Moreover, resistance of biofilmproducing strains to 13 tested antibiotics in this study highlighted the important role of these strains to cause severe infections, which do not respond to broad spectrum of antibiotics.…”

High Diversity of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates Based on Hypervariable Region Polymorphisms

“…Comparing these two methods, the sensitivity of the phenotypic method with cefoxitin discs is relatively lower than with the genotypic method of mecA gene identification. However, even with the former method, the frequency of MRSA strains in this study was determined to be 35.8%, which is comparable to the rate found by other investigators in Iran (18,19). Nevertheless, this amount, compared to the results of previous studies, with a prevalence 80% in Tabriz (20), is different.…”

Characteristics of Methicillin Resistant Staphylococcus aureus Strains Isolated From Poultry in Iran

“…In other studies from Iran, the prevalence of penicillin resistance among MRSA isolates was 100% (10,(26)(27)(28)30). Possibly, the general use of ampicillin for the treatment of infections in poultry may explain this finding.…”

“…The occurrence of erythromycin resistance among poultry MRSA was significantly lower than that observed among MRSA of human origin, in Iran (10,(26)(27)(28)(29). Macrolides are not normally used for therapy of infections in poultry in Denmark, whereas the frequent occurrence of macrolide resistance might reflect the use of the spiramycin, as a growth promoter of poultry, in Iran.…”