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

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA), particularly the multidrug-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 MRSAisolates 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.

Microbial Susceptibility and Plasmid Profiles of Methicillin-Resistant Staphylococcus aureus and Methicillin-Susceptible S. aureus

“…In the present study, the prevalence of MDR strains among MRSA was found to be quite high (> 80%). In various other reports from other countries, the prevalence of such strains has ranged from 80% to 100% to (21-23). This high prevalence could be attributed to several factors like irrational use of multiple antibiotics, prolonged hospitalization, nasal carriage of MRSA, lack of awareness among hospital staff and ineffective control measures.…”

Genetic Characterization of Methicillin Resistant and Sensitive, Vancomycin Intermediate Staphylococcus aureus Strains Isolated from Different Iranian Hospitals

“…ST1283 and ST585 are single-locus variants (SLV) of ST239, the endemic strain of Asia (Figure 1) which our data suggest to be the probable common ancestor of our MRSA-VISA isolates. All of our five VISA isolates belonged to clonal complex 8 (CC8) that is the major endemic S. aureus clone (particularly MRSA) in Asia and also is one of the pandemic MRSA clones [33, 39–44]. …”

Could chloramphenicol be used against ESKAPE pathogens? A review ofin vitrodata in the literature from the 21st century

“…Indeed, Livermore et al recently reported that the susceptibility to chloramphenicol among 20 carbapenemase-producing Enterobacter strains was only 20% [7]. According to this observation, we could speculate that the Enterobacter phenotype is similar to that of K. pneumoniae, where resistance to [60] 2009 Pakistan 501 KB 90 [61] 2010 Pakistan 139 KB 93 [62] 2010 India 69 KB 60 [63] 2010 USA 21 MicroScan 91 [64] 2010 Pakistan 174 KB; E-test 7 [65] 2011 Greece 44 KB 70 [66] 2011 USA 170 -96 [67] 2011 Canada 51 Sensititre 98 [68] 2011 Iran 140 KB 100 [69] 2011 Libya 62 KB 61 [70] 2011 Nigeria 16 KB 0 [71] 2012 Turkey 34 -94 [72] 2012 Nigeria 46 KB 20 [73] 2012 Spain 204 KB 99 [74] 2012 India 135 KB 94 [75] 2012 Brazil 1998 (Y): 48 KB 4 [76] 2008 (Y): 56 70 2012 USA 270 -100 [77] 2012 China 163 CA -85 [78] 77 HA 87 † All the strains belonged to a single clone. ‡…”