Studying the resistance of methicillin –resistant staphylococcus aureus against Different groups of antibiotics.

Abstract

Back ground: MRSA developed resistance to β-lactam antibiotics through the acquisition of
the mecA gene that encodes penicillin-binding protein 2a (PBP2a), which has a significantly
reduced affinity for β-lactam antibiotics, thereby conferring β- lactam resistance . The detection
of mecA by the (PCR) is considered a gold-standard technique for methicillin resistance
detection .
Objective:This study was aimed to isolation and identification of S.aureus by traditional and
molecular methods and determine their susceptibility to different groups of antibiotics.
Materials and Methods: Two hundred and ten samples were collected from different sources
of patients in different age groups and for the period from the beginning of January 2015 until
the end of June 2015, from different Hospitals in Baghdad (Ibn Albalady, Al Yarmouk,
Baghdad teaching hospital and AlKindy).
Results: Depending on the molecular methods (137) out of (210) isolates were methicillin
–resistant Staphylococcus aureus MRSA. Antibiotic sensitivity test was conducted using 20
types of antibiotics include:- Amikacin, Amoxicillin, Ampicillin, Azithromycin, Cefoxitin,
Ciprofloxacin, Clarerythromycin, Clindamycin, Chloramphenicol, Erythromycin, Gentamycin,
Methicillin, Norfloxacin, Oxacillin, Penicillin, Rifampin, Teicoplanin, Tetracycline,
Tobramycin and Vancomycin.
Conclusion: The results showed that the highest resistance was among beta-lactam group,
where the ratio was 100% resistance to Ampicillin and Penicillin, and ratio of 91% to 86.66%
and 86.66% resistance to Methicillin, Oxacillin and Amoxicillin respectively.
The lowest resistance was among a group of antagonists Aminoglycosides resistance and ratios
was 37.77%, 31.11% and 35.55% to Amikacin, Tobramycin and Gentamycin, respectively,
while the rest have different kinds of antibiotics effects.