title: Current pattern of antibiotic resistance in Staphylococcus aureus clinical isolates and the emergence of vancomycin resistance.
abstract: OBJECTIVE
  To determine the pattern of antibiotic resistance in the clinical isolates of Staphylococcus (S.) aureus, Methicillin Resistant S. aureus (MRSA) and define the possible emergence of Vancomycin resistant S. aureus (VRSA) in Karachi.
  
  
  METHODS
  An observational study.
  
  
  METHODS
  Essa Laboratories and Department of Molecular Genetics, Ziauddin Hospital, from January to December 2009.
  
  
  METHODS
  Staphylococcal isolates from different clinical specimens, pus, urine, blood, high vaginal swab and other secretions received at Ziauddun laboratories and Dr.Essa laboratories were collected. The specimens were inoculated on blood agar, MacConkey agar and Chrom agar. Antibiotic susceptibility to conventional antibiotics was done by disc diffusion, and E-test. Methicillin resistance was tested by using Oxacillin and Methicillin disks and confirmed by gold standard PCR for presence of mecA gene. All MRSA strains were subjected in addition to Vancomycin screen agar test.
  
  
  RESULTS
  Out of the 450 S. aureus isolates 174 (38.6%) were found to be MRSA. In those isolates, high resistance was found to Cefixime (100%) Doxicycline (100%) Oxacillin (96.5%) Gentamicin, (96.3%), Timethoprim/Sulfametoxazole (95.6%) Chloramphenicol (93%) Tobramicin (81.03%), Ofloxacin (72.4%) and Ciprofloxacin (63.7%). Low resistance was found to Ceftazidine (36%), Amoxicillin/Clavulanate (32.7%), Fosfomycin (31%), Cefroxime (24%), Amikacin (17.2%) and Meropenem (13%). One isolate was found to be Vancomycin resistant (MIC 32 μg/ml). Four isolates had intermediate resistance, with two strains having MIC of 16μg/ml and two having MIC of 8μg/ml. These strains were also resistant to all the other tested antibiotics except Linezolid to which all isolates were susceptible.
  
  
  CONCLUSIONS
  Antibiotic resistance to all the conventionally used antibiotics was high in the tested isolates. All the strains were susceptible to Linezolid which is an expensive alternative with adverse side effects. Judicious use of antibiotics focused on the compliance and formation of antibiotic policy guide lines is highly recommended.
authors.affiliation: Department of Microbiology, Dow Medical College, Karachi. y.taj@hotmail.com
authors.forename: Yasmeen
authors.initials: Y
authors.lastname: Taj
authors.forename: Farhan Essa
authors.initials: FE
authors.lastname: Abdullah
authors.forename: Shahana Urooj
authors.initials: SU
authors.lastname: Kazmi
mesh_terms: D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus; D008826:Microbial Sensitivity Tests; D010154:Pakistan / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000453:epidemiology; D013211:Staphylococcus aureus / Q000187:drug effects*; D020713:Vancomycin Resistance
chemical_list: D004269:DNA, Bacterial