Keywords: Methicillin resistant Staphylococcus aureus, oxacillin
, cefoxitin, PCR.
(6) MICs were determined by broth microdilution (BMD) for daptomycin, linezolid, oxacillin
, teicoplanin, vancomycin, and TMP/STX (Sigma-Aldrich Chemical Company, St Louis, USA).
and Cefoxitin were 100% (21) resistant for MRSA and sensitive for MSSA.
All of 134 isolates were found resistant to oxacillin
, aziocillin, ceftriaxone, piperacillin/tazobactem, cloxacillin and mupirocin (Fig-1).
, Cefoxitin and Ampicillin faced 100% resistance while Vancomycin, Cefixime and Cefotaxime had >78 % of resistance from MDR isolates from both study areas.
Using a sterile swab, contents of the tube were distributed on a 150-mm plate containing Mueller-Hinton agar, and 10 equidistant paper discs containing antibiotics: 20[micro]g amoxicillin + 10[micro]g clavulanic acid, 30[micro]g cephalexin, 5[micro]g enrofloxacin, 10[micro]g gentamicin, oxacillin
, 10[micro]g penicillin, 30[micro]g tetracycline, and 1.25g/23.75[micro]g trimethoprim-sulfamethoxazole (DME[R] Laboratory, Aracatuba, Sao Paulo, Brazil).
The E-Test (Hi Media Laboratories Pvt, Ltd, Mumbai, India) for determining oxacillin
MICs were performed on Muller-Hilton agar plate with 2%NaCl as per instruction and plates were incubated at 35[degrees]C for 24hrs.
Different phenotypic methods such as oxacillin
and cefoxitin disc diffusion test, oxacillin
agar screening test, and determination of minimum inhibitory concentration (MIC) for oxacillin
and cefoxitin are available in clinical laboratories.[6-9] Phenotypic expression is affected by various conditions such as temperature, osmolarity of the medium and inoculum size that may affect the accuracy of the methods used to detect methicillin resistance.
Isolates from his third incident infection culture in August 2012 showed the same molecular characteristics as previous samples, but 2 different susceptibility patterns: 1 isolate was the same as previous, while another showed additional phenotypic resistance to oxacillin
(MIC 4 [micro]g/mL by broth dilution), making this a borderline-resistant S.
Penicillin minimum inhibitory concentration (MIC) values were measured using E-test method (bioMerieux, France) on Mueller-Hinton agar containing 5% sheep blood; oxacillin
, erythromycin, clindamycine, vancomycine, tetracycline, ofloxacin, levofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, rifampicin and linezolid susceptibilities were measured using disk diffusion technique on the same agar according to CLSI guidelines.
The Kirby-Bauer Disk Diffusion Susceptibility test was used to obtain the antimicrobial resistance profile of the isolates for clindamycin (2 [micro]g), vancomycin (30 [micro]g), trimethoprim-sulfamethoxazole (25 [micro]g), tetracycline (30 [micro]), penicillin G (10 IU), oxacillin
(1 [micro]G), and cefoxitin (30 [micro]g).