the study was carried out in mustafa kemal university , faculty of medicine , department of medical microbiology ( hatay , turkey ) between july 2007 and august 2009 . a total of 298 clinical isolates of staphylococcai were isolated from blood ( 29 , 9.7% ) , wounds ( 145 , 48.7% ) , urine ( 42 , 14.1% ) , pus ( 59 , 19.8% ) , and other sources samples ( 23 , 7.7% ) . of the 298 staphylococcal isolates , 159 ( 53.4% ) were coagulase - negative staphylococci ( cons ) and 139 ( 46.6% ) isolates were identified as the s. aureus . the samples were placed into modified amines charcoal transport medium ( difco laboratories , usa ) , and were sent immediately to the microbiology laboratory . the samples were inoculated onto 5 per cent sheep blood agar plates ( difco laboratories , usa ) , and incubated at 37c for 48 h. the identification of staphylococci was on the basis of colony morphology , gram staining , biochemical tests such as catalase and coagulase tests10 . isolates were stored at -70c in mueller - hinton broth ( merck , germany ) supplemented with 40 per cent glycerol ( v / v ) . disc diffusion - antimicrobial susceptibilities of the isolates were tested by the agar disk diffusion method on mueller - hinton agar ( tiantan biotechnology , pr china ) according to the clinical and laboratory standards institute ( clsi ) guidelines11 . antibiotic discs ( becton dickinson , usa ) were placed on mueller - hinton agar plates , incubated at 37c for 24 h , and the diameter of each zone was measured in millimeters . the following antibiotic discs were used : penicillin ( 10 u ) , erythromycin ( 15 g ) , oxacillin ( 1 g ) , tetracycline ( 30 g ) , gentamicin ( 10 g ) , amoxicillin - clavulanic acid ( 30 g ) , clindamycin ( 2 g ) , vancomycin ( 30 g ) , trimethoprim - sulphamethoxazole ( 25 g ) , and ciprofloxacin ( 5 g ) . oxacillin disc diffusion test - oxacillin disc susceptibility testing was performed on all isolates of s. aureus according to clsi recommendations using a 1 g oxacillin disc . oxacillin disc ( becton dickinson microbiology systems , usa ) were placed on mueller - hinton agar plates without nacl supplementation . s. aureus atcc 29213 and s. aureus atcc ( 43300 ) were chosen as the negative and positive control strains , respectively . determination of minimum inhibitory concentrations ( mic ) : mic values of antibiotics were determined by the broth microdilution test . all isolates were subcultured on blood agar and incubated for 24 h at 37 c . then , two - fold serial dilutions of each antibiotic were made in mueller - hinton broth to achieve a concentration range from 0 to 256 g / ml . after incubation at 37 for 24 h , the mic was defined as the lowest concentration of antibiotics that produced no growth . the broth microdilution tests were performed according to the clsi guidelines11 dna isolation : for nucleic acid isolation from staphylococcal isolates , the frozen samples were thawed rapidly , and were cultivated in brain - heart infusion broth ( merck , germany ) at 37c with shaking overnight . after incubation , bacterial cells were harvested by centrifugation at 3000  g for 10 min , the cell pellet was re - suspended in phosphate - buffered saline with 100 g of lysostaphin ( sigma , usa ) per ml , and incubated at 37c for 30 min . the phenol / chloroform extraction method was used for nucleic acid extraction and dna was precipitated in 1 ml 70 per cent ethanol . the dna precipitate was dissolved in 50 l of te buffer [ 10 mm tris chloride-1 mm edta ( ph 8.0 ) ] , and stored at -20c until processing . the oligonucleotide primers3 for the meca , fema , 16s rdna , aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia genes were selected and the primers for erm(a ) , erm(b ) , erm(c ) , tet(k ) , tet(m ) , clf a , msra and blaz , genes were selected based on earlier studies1314 ( table i ) . the primer sequences and predicted sizes used in the multiplex pcrs pcr method for aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia : the pcr amplification was performed in a 25 l reaction mixture [ 2.5 ml of 10x reaction buffer without mgcl2 ( promega corp . , usa ) ; 200 m of each deoxynucleoside triphospate ( ab gene , uk ) , 2 mm mgcl2 ; 2.5 pmol of each primer ( aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia ] and approximately 10 ng of template dna , and brought up to a 25 l final volume with distilled water . in order to reduce the formation of nonspecific extension products , a  hot - start pcr reactions were hot started for 5 min at 95c and placed on ice , and 1 u of taq polymerase ( fermentas , usa ) was added . reaction mixtures were subjected to 30 pcr cycles ( 95c for 2 min , 1 min at 54c and 1 min at 72 c ) . a final elongation step at 72c for 7 min was applied in a thermal cycler ( bioder / thermal blocks xp cycler , tokyo , japan ) . pcr method for 16s rdna , meca and fema : multiplex pcr conditions for 16s rdna , meca and fema included the same constituents as the procedure of aminoglycoside resistance genes except for the mgcl2 concentration ( 3.0 mm ) and the primers , which were used at 20 pmol of primers for 16s rdna , meca and fema . dna amplification was carried out in a thermal cycler and reactions were hot started for 5 min at 94c and placed on ice , and 1 u of taq polymerase ( fermentas , usa ) was added . reaction mixtures were subjected to 35 pcr cycles ( 94c for 2 min , 2 min at 55c , and 1 min at 72c ) . pcr method for erm(a ) , erm(b ) , erm(c ) , tet(k ) , tet(m ) , msra , blaz : the pcr amplification was carried out in a total volume of 25 l . pcr amplification was achieved as follows : 5 l of genomic dna ( approximately 50 ng ) sample was added to 20 l of pcr mixture ( 20 mmol / l tris - hcl , ph 8.4 ; 50 mmol / l kcl , 10 mmol / l mgcl2 , and 200 mol / l each of deoxynucleoside triphosphates ( dntps ) , 0.6 mol / l each primers and 1 u taq dna polymerase . the amplification process was started with an initial denaturation step ( 95 c , 3 min ) . each pcr reaction consisted of 30 cycles of amplification ( denaturation at 95c for 30 sec , annealing at 54 c for 30 sec , and dna chain extension at 72c for 30 sec ) . the resistance genes were studied in five different groups : group 1 ( meca and fema ) ; group 2 [ ( aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ) ] ; group 3 ( 16s rdna , erma , ermc ) ; group 4 ( msra , 16s rdna , ermc ) ; and group 5 ( erm b ) . after amplification of the resistance genes , 10 l of the pcr products were mixed with 3 l of loading buffer ( 10 % , w / v , ficoll 400 ; 10 mmol / l tris - hcl , ph 7.5 ; 50 mmol / l edta ; 0.25% bromophenol blue ) and then loaded onto a 2 per cent agarose gel and electrophoresis was performed in tris - borate - edta buffer containing 0.5 g of ethidium bromide per ml . the pcr products were analyzed in a 2 per cent ( w / v ) agarose gel in 1  tae buffer ( 40 mmol / l tris - acetate , 1 mmol / l edta ) . ethidium bromide ( 0.5 g / ml tae)-stained dna amplicons were visualized using a gel imaging system ( wealtec , dolphin - view , usa ) . statistical analysis : all data were evaluated by 2 test using statistical package for social sciences ( spss1 for windows v. 11.5 , chicago , usa ) software . disc diffusion - antimicrobial susceptibilities of the isolates were tested by the agar disk diffusion method on mueller - hinton agar ( tiantan biotechnology , pr china ) according to the clinical and laboratory standards institute ( clsi ) guidelines11 . antibiotic discs ( becton dickinson , usa ) were placed on mueller - hinton agar plates , incubated at 37c for 24 h , and the diameter of each zone was measured in millimeters . the following antibiotic discs were used : penicillin ( 10 u ) , erythromycin ( 15 g ) , oxacillin ( 1 g ) , tetracycline ( 30 g ) , gentamicin ( 10 g ) , amoxicillin - clavulanic acid ( 30 g ) , clindamycin ( 2 g ) , vancomycin ( 30 g ) , trimethoprim - sulphamethoxazole ( 25 g ) , and ciprofloxacin ( 5 g ) . oxacillin disc diffusion test - oxacillin disc susceptibility testing was performed on all isolates of s. aureus according to clsi recommendations using a 1 g oxacillin disc . oxacillin disc ( becton dickinson microbiology systems , usa ) were placed on mueller - hinton agar plates without nacl supplementation . s. aureus atcc 29213 and s. aureus atcc ( 43300 ) were chosen as the negative and positive control strains , respectively . determination of minimum inhibitory concentrations ( mic ) : mic values of antibiotics were determined by the broth microdilution test . all isolates were subcultured on blood agar and incubated for 24 h at 37 c . then , two - fold serial dilutions of each antibiotic were made in mueller - hinton broth to achieve a concentration range from 0 to 256 g / ml . after incubation at 37 for 24 h , the mic was defined as the lowest concentration of antibiotics that produced no growth . the broth microdilution tests were performed according to the clsi guidelines11 dna isolation : for nucleic acid isolation from staphylococcal isolates , the frozen samples were thawed rapidly , and were cultivated in brain - heart infusion broth ( merck , germany ) at 37c with shaking overnight . after incubation , bacterial cells were harvested by centrifugation at 3000  g for 10 min , the cell pellet was re - suspended in phosphate - buffered saline with 100 g of lysostaphin ( sigma , usa ) per ml , and incubated at 37c for 30 min . the phenol / chloroform extraction method was used for nucleic acid extraction and dna was precipitated in 1 ml 70 per cent ethanol . the dna precipitate was dissolved in 50 l of te buffer [ 10 mm tris chloride-1 mm edta ( ph 8.0 ) ] , and stored at -20c until processing . the oligonucleotide primers3 for the meca , fema , 16s rdna , aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia genes were selected and the primers for erm(a ) , erm(b ) , erm(c ) , tet(k ) , tet(m ) , clf a , msra and blaz , genes were selected based on earlier studies1314 ( table i ) . the primer sequences and predicted sizes used in the multiplex pcrs pcr method for aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia : the pcr amplification was performed in a 25 l reaction mixture [ 2.5 ml of 10x reaction buffer without mgcl2 ( promega corp . , usa ) ; 200 m of each deoxynucleoside triphospate ( ab gene , uk ) , 2 mm mgcl2 ; 2.5 pmol of each primer ( aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia ] and approximately 10 ng of template dna , and brought up to a 25 l final volume with distilled water . in order to reduce the formation of nonspecific extension products , a  hot - start pcr reactions were hot started for 5 min at 95c and placed on ice , and 1 u of taq polymerase ( fermentas , usa ) was added . reaction mixtures were subjected to 30 pcr cycles ( 95c for 2 min , 1 min at 54c and 1 min at 72 c ) . a final elongation step at 72c for 7 min was applied in a thermal cycler ( bioder / thermal blocks xp cycler , tokyo , japan ) . pcr method for 16s rdna , meca and fema : multiplex pcr conditions for 16s rdna , meca and fema included the same constituents as the procedure of aminoglycoside resistance genes except for the mgcl2 concentration ( 3.0 mm ) and the primers , which were used at 20 pmol of primers for 16s rdna , meca and fema . dna amplification was carried out in a thermal cycler and reactions were hot started for 5 min at 94c and placed on ice , and 1 u of taq polymerase ( fermentas , usa ) was added . reaction mixtures were subjected to 35 pcr cycles ( 94c for 2 min , 2 min at 55c , and 1 min at 72c ) . a final elongation step at 72c for 7 min pcr method for erm(a ) , erm(b ) , erm(c ) , tet(k ) , tet(m ) , msra , blaz : the pcr amplification was carried out in a total volume of 25 l . pcr amplification was achieved as follows : 5 l of genomic dna ( approximately 50 ng ) sample was added to 20 l of pcr mixture ( 20 mmol / l tris - hcl , ph 8.4 ; 50 mmol / l kcl , 10 mmol / l mgcl2 , and 200 mol / l each of deoxynucleoside triphosphates ( dntps ) , 0.6 mol / l each primers and 1 u taq dna polymerase . the amplification process was started with an initial denaturation step ( 95 c , 3 min ) . each pcr reaction consisted of 30 cycles of amplification ( denaturation at 95c for 30 sec , annealing at 54 c for 30 sec , and dna chain extension at 72c for 30 sec ) . the resistance genes were studied in five different groups : group 1 ( meca and fema ) ; group 2 [ ( aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ) ] ; group 3 ( 16s rdna , erma , ermc ) ; group 4 ( msra , 16s rdna , ermc ) ; and group 5 ( erm b ) . after amplification of the resistance genes , 10 l of the pcr products were mixed with 3 l of loading buffer ( 10 % , w / v , ficoll 400 ; 10 mmol / l tris - hcl , ph 7.5 ; 50 mmol / l edta ; 0.25% bromophenol blue ) and then loaded onto a 2 per cent agarose gel and electrophoresis was performed in tris - borate - edta buffer containing 0.5 g of ethidium bromide per ml . the pcr products were analyzed in a 2 per cent ( w / v ) agarose gel in 1  tae buffer ( 40 mmol / l tris - acetate , 1 mmol / l edta ) . ethidium bromide ( 0.5 g / ml tae)-stained dna amplicons were visualized using a gel imaging system ( wealtec , dolphin - view , usa ) . statistical analysis : all data were evaluated by 2 test using statistical package for social sciences ( spss1 for windows v. 11.5 , chicago , usa ) software . disc diffusion - antimicrobial susceptibilities of the isolates were tested by the agar disk diffusion method on mueller - hinton agar ( tiantan biotechnology , pr china ) according to the clinical and laboratory standards institute ( clsi ) guidelines11 . antibiotic discs ( becton dickinson , usa ) were placed on mueller - hinton agar plates , incubated at 37c for 24 h , and the diameter of each zone was measured in millimeters . the following antibiotic discs were used : penicillin ( 10 u ) , erythromycin ( 15 g ) , oxacillin ( 1 g ) , tetracycline ( 30 g ) , gentamicin ( 10 g ) , amoxicillin - clavulanic acid ( 30 g ) , clindamycin ( 2 g ) , vancomycin ( 30 g ) , trimethoprim - sulphamethoxazole ( 25 g ) , and ciprofloxacin ( 5 g ) . oxacillin disc diffusion test - oxacillin disc susceptibility testing was performed on all isolates of s. aureus according to clsi recommendations using a 1 g oxacillin disc . oxacillin disc ( becton dickinson microbiology systems , usa ) were placed on mueller - hinton agar plates without nacl supplementation . s. aureus atcc 29213 and s. aureus atcc ( 43300 ) were chosen as the negative and positive control strains , respectively . determination of minimum inhibitory concentrations ( mic ) : mic values of antibiotics were determined by the broth microdilution test . all isolates were subcultured on blood agar and incubated for 24 h at 37 c . then , two - fold serial dilutions of each antibiotic were made in mueller - hinton broth to achieve a concentration range from 0 to 256 g / ml . after incubation at 37 for 24 h , the mic was defined as the lowest concentration of antibiotics that produced no growth . the broth microdilution tests were performed according to the clsi guidelines11 dna isolation : for nucleic acid isolation from staphylococcal isolates , the frozen samples were thawed rapidly , and were cultivated in brain - heart infusion broth ( merck , germany ) at 37c with shaking overnight . after incubation , bacterial cells were harvested by centrifugation at 3000  g for 10 min , the cell pellet was re - suspended in phosphate - buffered saline with 100 g of lysostaphin ( sigma , usa ) per ml , and incubated at 37c for 30 min . the phenol / chloroform extraction method was used for nucleic acid extraction and dna was precipitated in 1 ml 70 per cent ethanol . the dna precipitate was dissolved in 50 l of te buffer [ 10 mm tris chloride-1 mm edta ( ph 8.0 ) ] , and stored at -20c until processing . the oligonucleotide primers3 for the meca , fema , 16s rdna , aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia genes were selected and the primers for erm(a ) , erm(b ) , erm(c ) , tet(k ) , tet(m ) , clf a , msra and blaz , genes were selected based on earlier studies1314 ( table i ) . the primer sequences and predicted sizes used in the multiplex pcrs pcr method for aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia : the pcr amplification was performed in a 25 l reaction mixture [ 2.5 ml of 10x reaction buffer without mgcl2 ( promega corp . , usa ) ; 200 m of each deoxynucleoside triphospate ( ab gene , uk ) , 2 mm mgcl2 ; 2.5 pmol of each primer ( aac(6)/aph(2  ) , aph(3)-iiia and ant(4)-ia ] and approximately 10 ng of template dna , and brought up to a 25 l final volume with distilled water . in order to reduce the formation of nonspecific extension products , a  hot - start pcr reactions were hot started for 5 min at 95c and placed on ice , and 1 u of taq polymerase ( fermentas , usa ) was added . reaction mixtures were subjected to 30 pcr cycles ( 95c for 2 min , 1 min at 54c and 1 min at 72 c ) . a final elongation step at 72c for 7 min was applied in a thermal cycler ( bioder / thermal blocks xp cycler , tokyo , japan ) . pcr method for 16s rdna , meca and fema : multiplex pcr conditions for 16s rdna , meca and fema included the same constituents as the procedure of aminoglycoside resistance genes except for the mgcl2 concentration ( 3.0 mm ) and the primers , which were used at 20 pmol of primers for 16s rdna , meca and fema . dna amplification was carried out in a thermal cycler and reactions were hot started for 5 min at 94c and placed on ice , and 1 u of taq polymerase ( fermentas , usa ) was added . reaction mixtures were subjected to 35 pcr cycles ( 94c for 2 min , 2 min at 55c , and 1 min at 72c ) . a final elongation step at 72c for 7 min pcr method for erm(a ) , erm(b ) , erm(c ) , tet(k ) , tet(m ) , msra , blaz : the pcr amplification was carried out in a total volume of 25 l . pcr amplification was achieved as follows : 5 l of genomic dna ( approximately 50 ng ) sample was added to 20 l of pcr mixture ( 20 mmol / l tris - hcl , ph 8.4 ; 50 mmol / l kcl , 10 mmol / l mgcl2 , and 200 mol / l each of deoxynucleoside triphosphates ( dntps ) , 0.6 mol / l each primers and 1 u taq dna polymerase . the amplification process was started with an initial denaturation step ( 95 c , 3 min ) . each pcr reaction consisted of 30 cycles of amplification ( denaturation at 95c for 30 sec , annealing at 54 c for 30 sec , and dna chain extension at 72c for 30 sec ) . the resistance genes were studied in five different groups : group 1 ( meca and fema ) ; group 2 [ ( aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ) ] ; group 3 ( 16s rdna , erma , ermc ) ; group 4 ( msra , 16s rdna , ermc ) ; and group 5 ( erm b ) . after amplification of the resistance genes , 10 l of the pcr products were mixed with 3 l of loading buffer ( 10 % , w / v , ficoll 400 ; 10 mmol / l tris - hcl , ph 7.5 ; 50 mmol / l edta ; 0.25% bromophenol blue ) and then loaded onto a 2 per cent agarose gel and electrophoresis was performed in tris - borate - edta buffer containing 0.5 g of ethidium bromide per ml . the pcr products were analyzed in a 2 per cent ( w / v ) agarose gel in 1  tae buffer ( 40 mmol / l tris - acetate , 1 mmol / l edta ) . ethidium bromide ( 0.5 g / ml tae)-stained dna amplicons were visualized using a gel imaging system ( wealtec , dolphin - view , usa ) . statistical analysis : all data were evaluated by 2 test using statistical package for social sciences ( spss1 for windows v. 11.5 , chicago , usa ) software . a total of 16.5 per cent ( 23/139 ) of the coagulase positive staphylococcal isolates showed resistance to methicillin and 18.9 per cent ( 30/159 ) coagulase negative isolates showed methicillin resistance , phenotypically . the highest drug resistance was obtained against penicillin in both s. aureus 92.8 per cent and the cons 86.6 per cent . overall , antibiotics resistance rates for gentamicin , tetracycline and erythromycin were 31.5 , 35.6 , 48.7 and 87.9 per cent , respectively ( table ii ) . the staphylococcal isolates showed moderate resistance to amoxicillin - clavulanic acid ( 28.9% ) , and trimethoprim - sulphamethoxazole ( 32.2% ) . both cons and s.aureus strains were vancomycin susceptible table ii . the mic values and the resistance patterns of staphylococci by the disc diffusion method the susceptibility results determined by conventional methods were compared with the results of the multiplex pcr assay ( table iii ) . methicillin resistance rate among 139 s. aureus isolates was 16.5 and 25.9 per cent ( 36/139 ) of s. aureus isolates carried meca gene . methicillin resistance rate in cons was 18.9 and 29.6 per cent of cons carried meca gene . thirty isolates which were phenotypically methicillin - susceptible , were found to carry the meca gene . while a total of 139 isolates were identified as s. aureus by phenotypic methods , the presence of the fema gene was determined in 151 ( table iii ) . the rates of antibiotic resistance genes in staphylococci by multiplex pcr method among ame genes , aac(6)/aph(2  ) was detected in 18.5 per cent , aph(3)-iiia and ant(4)-ia were found in 11.4 and 7.4 per cent of the isolates , respectively . all 94 isolates identified as gentamicin resistant phenotypically contained at least one of the gentamicin resistance genes [ aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ] ( fig . a total of 17 gentamicin - susceptible isolates were found positive in terms of one or more resistance genes [ aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ] by multiplex pcr ( table iv ) . ethidium bromide - stained multiplex pcr products after gel electrophoresis for the aac(6)/aph(2  ) ( 491 bp ) , aph(3)-iiia ( 242 bp ) and ant(4)-ia ( 135 bp ) genes . lanes : 1 - 4 , 9 , 10 , 12 , 14 and 15 ; aac(6)/aph(2  ) ; lane 7 : dna marker ( molecular size standard ) ; lane 8 : negative control ; lane 1 and 4 : aac(6)/aph(2  ) and aph(3)-iiia ; lane 11 : aph(3)-iiia ; lane 12 : aac(6)/aph(2  ) and ant(4)-ia . relationship between gentamicin resistance and the presence of three resistance genes ( aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ) a total of 145 isolates were resistant to erythromycin , and contained at least one of the erythromycin resistance genes ( erma , ermb , ermc and msra ) . the erma and ermc genes were presenting 77 ; ermb could be detected in 13 isolates ( fig . ethidium bromide - stained multiplex pcr products after gel electrophoresis for the 16s rdna ( 420 bp ) , erm(a ) ( 190 bp ) and erm(c ) ( 299 bp ) genes . lanes : 1 - 5 , and 7 - 11 ; 16s rdna ; lane 4 and 7 : 16s rdna , erm(a ) and erm(c ) ; lane 6 : dna marker ( molecular size standard ) ; lane 12 : negative control . relationship between erythromycin resistance and the presence of four resistance genes ( erma , ermb , ermc , or msra ) a total of 106 staphylococcal isolates were found resistant to tetracycline , phenotypically , 121 isolates were resistant to tetracycline and carried either tetk or tetm or both resistance genes ( table vi ) . with regards to blaz gene the 130 ( 93.5% ) s. aureus isolates carrying the blaz gene expressed the phenotype , and the presence of the blaz gene was found as 86.8 per cent ( 138/159 ) among the coagulase negative staphylococci ( table vii ) . relationship between tetracycline resistance and the presence of the tetk and tetm genes relationship between penicillin resistance and the presence of the blaz gene in the present study , the results of antibiotic susceptibility by disk diffusion method were compared with gene analysis results in staphylococcal isolates . the phenotypic expression of antimicrobial resistance has been reported to be influenced by various factors15 . the antimicrobial susceptibility test was performed for all isolates of s. aureus and cons by disc diffusion and broth microdilution test . antibiotic susceptibility test results showed a high level of resistance among the staphylococal isolates to most of the commonly used antimicrobials . in our study , all staphylococcal isolates were found as positive by pcr for 16s rdna gene and , all s. aureus isolates were positive to the species specific fema gene . methicillin resistance in staphylococci has been reported to be associated with the presence of penicillin - binding proteins , pbp2 ( pbp2a ) , encoded by the meca gene . the meca gene may be heterogeneously expressed and , therefore however , the detection of meca gene by pcr techniques is considered the gold standard method . also , phenotypic methods require at least 24 h for evaluation of the results23 methicillin resistance was observed in 17.8 per cent isolates when tested by methicillin disk diffusion method , whereas 27.9 per cent isolates had meca gene . results about resistance to methicillin found in this study were lower than those reported from other parts of turkey1617 , but were in accordance with those in similar studies from europe ( 25% ) but were lower than those in usa1819 our results showed that the blaz gene was widely spread among both s. aureus and cons . in various studies from our country , penicillin resistance has been reported between 61 and 100 per cent2021 . the resistance rate in various countries of the world ranged from 50 to > 91 per cent2223 . the staphylococcal isolates were analyzed for the presence of the aminoglycoside - modifying enzyme genes aac(6)/aph(2  ) , aph(3)-iiia , and ant(4)-ia by multiplex pcr . the presence of at least one of the ame genes was seen in 111 of 298 isolates . a total 62.8 per cent isolates negative for ame genes were resistant to gentamicin . in accordance with previous studies35 , the aac(6)/aph(2  ) gene was the most prevalent ame gene in staphylococci . in our study , aac(6)-aph(2  ) gene was the most frequently found gene among mrsa isolated . ida et al6 from japan reported that aac(6)/aph(2  ) gene in mrsa strains was encountered less frequently among clinical isolates6 . all isolates found to be resistant to erythromycin by phenotypic methods contained at least 1 erythromycin resistance gene . while resistance to erythromycin in staphylococci was found as 48.7 per cent by phenotypic methods , this ratio was 55.4 per cent by multiplex pcr assay . erm a , erm b and msra genes in s. aureus isolates were found at higher rates than in cons , and among the cons , ermc gene was the more prevalent . in 34 isolates , neither erma nor ermc gene erytromycin resistance might be due to the presence of msra or ermb gene as previously described in cons24 . lim et al25 reported that the erma gene was more prevalent than the other erytromycin resistance genes in s. aureus isolates , and ermc gene was found mostly in cons . similarly , in a study performed by martineau et al14 , the ermc gene has been reported to be more prevalent in cons . however , erma has been reported to be the more common gene in cons in another study26 . our results were consistent with that of lim et al25 and martineau et al14 , but were contradictory to that of thakker - varia et al26 . in the present study , the phenotypic resistance to tetracycline in s. aureus and cons was observed as 41 and 30.8 per cent , respectively . whereas 42.4 per cent s. aureus isolates carried the tetk and tetm genes , 39 per cent of cons tetracycline resistance genes tetk and tetm were found positive by pcr method in 15 isolates which were phenotypically sensitive to tetracycline . identification and determination of the susceptibility to antibiotics of staphylococci by conventional methods requires a minimum of two - days period , whereas the detection of antibiotic resistance genes by pcr assay can be done within a few hours . rapid and reliable methods for antibiotic susceptibility are important to institute appropriate therapy . multiplex pcr can be used for confirmation of the results obtained by conventional phenotypic methods when needed .
background & objectives : this study was carried out to evaluate the association between the antibiotic susceptibility patterns and the antibiotic resistance genes in staphylococcal isolates obtained from various clinical samples of patients attending a teaching hospital in hatay , turkey.methods:a total of 298 staphylococci clinical isolates were subjected to antimicrobial susceptibility testing . 
 the genes implicated in resistance to oxacillin ( meca ) , gentamicin ( aac(6)/aph(2  ) , aph(3-iiia , ant(4)-ia ) , erythromycin ( erma , ermb , ermc , and msra ) , tetracyclin ( tetk , tetm ) , and penicillin ( blaz ) were amplified using multiplex pcr method.results:methicillin resistance rate among 139 staphlococcus aureus isolates was 16.5 and 25.9 per cent of s. aureus carried meca gene . 
 of the 159 cons isolates , methicillin resistance rate was 18.9 and 29.6 per cent carried meca gene . 
 ninety four isolates identified as gentamicin resistant phenotypically , contained at least one of the gentamicin resistance genes [ aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ] , 17 gentamicin - susceptible isolates were found as positive in terms of one or more resistance genes [ aac(6)/aph(2  ) , aph(3)-iiia , ant(4)-ia ] by multiplex pcr . 
 a total of 165 isolates were resistant to erythromycin , and contained at least one of the erythromycin resistance genes ( erma , ermb , ermc and msra ) . 
 phenotypically , 106 staphylococcal isolates were resistant to tetracycline , 121 isolates carried either tetk or tetm or both resistance genes . 
 the majority of staphylococci tested possessed the blaz gene ( 89.9%).interpretation & conclusions : the present results showed that the phenotypic antibiotic susceptibility patterns were not similar to those obtained by genotyping done by multiplex pcr . 
 rapid and reliable methods for antibiotic susceptibility are important to determine the appropriate therapy decisions . multiplex pcr can be used for confirmation of the results obtained by conventional phenotypic methods , when needed .