Antibiotic Resistance Pattern of Methicillin Resistant and Methicillin Sensitive Staphylococcus aureus Isolates in Tehran, Iran

Abstract

A B S T R A C TBackground: Staphylococcus aureus is associated with different infections ranging from skin and soft tissue infections to endocarditis and fatal pneumonia. S. aureus is still the most common bacterial species isolated from inpatient specimens and the second most common from outpatient specimens. Today, methicillin resistant S. aureus (MRSA) isolates are present in the hospitals of most countries and are often resistant to several antibiotics. Objectives: This study was conducted from 2007 to 2011 to detect prevalence and antibiotic resistance patterns among MRSA and methicillin sensitive S. aureus (MSSA) isolated from hospitals in Tehran, Iran. Materials and Methods: Totally 726 isolates of S. aureus were collected from three referral hospitals in Tehran. All isolates were identified at the species level by standard biochemical tests. Susceptibility to eighteen antibiotics was determined by disc diffusion method. Then oxacillin and vancomycin minimum inhibitory concentration (MIC) of resistant isolates was also determined using Etest. mecA gene was detected using specific primers. Results: A total of 216 (30%) strains were found to be MRSA isolates. The highest antibiotic resistance was to penicillin, clindamycin, tobramycin and tetracycline respectively. Ninety three and 61% of MRSA and MSSA isolates were multidrug resistant (MDR) respectively. However, no strain was resistant to vancomycin, synercid, linezolid and chloramphenicol. Sixty nine percent of MRSA isolates showed high level of resistance to oxacillin (MIC ≥ 256 µg/mL). mecA gene was detected among all MRSA isolates. Conclusions: Although the frequency of MRSA isolates in the current study was low, resistance to other antibiotics was high and most of the isolates were found to be MDR. Regular surveillance of hospital-associated infections and monitoring of their antibiotic sensitivity patterns are required to reduce MRSA prevalence. High frequency of MDR isolates of S. aureus could be considered as an urgent warning for public health.

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.…”

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.…”

Staphylococcus and Linezolid Resistance in Iran

“…In a study conducted on 726 S. aureus isolates (2007 to 2011) from 3 referral hospitals in Tehran (Iran), 30% of strains were found to be MRSA and mec A gene was detected among all MRSA isolates. No strains were resistant to vancomycin, synercid, linezolid, and chloramphenicol (5). In a random sample population from 4 hospitals including various clinical samples in Tabriz from year 2005 to 2012, 151 Staphylococcus aureus isolates were separated and meca gene, representative of MRSA was found in 35%, and 95% were resistant to penicillin and all isolates were susceptible to vancomycin and teicoplanin yet 5.9% were resistant to linezolid (6).…”

“…There are very few reports of vancomycin and linezolid resistant MRSA in Iran (4,5,17); Fathollahzadeh (2004 to 2005; Tehran) reported that 99 out of 277 (36%) hospitaladmitted wound or blood specimens were MRSA Staphylococcus aureus isolates. All were susceptible to vancomycin, teicoplanin, linezolid, and tigecycline.…”