“Classical” MRSA detection S451 blood culture bottle (Bactec Plus/F;BD) and clinical sample were directly inoculated to primary culture media and MRSA ID (bioM´ erieux, France). All cultures were incubated in aerobic condition at 370C for 24-48 h. Suspect colonies were identified as MRSA based on positive reaction on the tube coagulase test with rabbit plasma, the detection of DNase and growth on Mueller-Hinton (MH) oxacillin agar (6 mg of oxacillin/mL, according to CLSI). Inoculated MRSA ID plates were interperated in accordance with the manufacturer’ s instructions. Growth of colonies showing distinctive green coloration was considered to be positive. No growth or colonies with colours other than green were considered negative. Discordant results were confirmed by mecA gene PCR. Results: The results obtained with MRSA ID are summarised in Tables 1 and 2. Three methicillin-susceptible S. aureus (MSSA) isolates gave false-positive results on MRSA ID and these strains gave negative result with the mecA PCR. Table 1. Results for MRSA ID medium after 24 h and 48 h of incubation No. strains with a positive test result/total no. of strains (%) after: Organism 24 h 48 h MSSA 2/34 (5.9) 3/34 (8.8) MRSA 54/56 (96.4) 56/56 (100) Table 2. Strains producing green colonies which have a different appearance from MRSA colonies Organism No. of strains detected on medium Aerococcus viridans 1 Acinetobacter baumannii 1 Bacillus sp 1 Brucella sp 2 Candida sp 4 Enterococcus sp 2 Enterobacter gergovias 1 Stenotrophomonas maltophilia 4 Conclusions: (1) MRSA ID is highly effective for the isolation and presumptive identification of MRSA directly from wound samples and blood cultures. (2) The use of MRSA ID with primary culture media should decrease the time (18-24 h) to reporting positive results compared with conventional methods. P1604 Evaluation of a new chromogenic medium SaSelect for identification of Staphylococcus aureus C. Daurel, R. Leclercq (Caen, FR) Objectives: The objectives were to compare the sensitivities and specificities of SaSelect, a new chromogenic medium, and Mannitol salt agar medium (MSA, Chapman) associated with a slide coagulase test, for rapid and direct identification of Staphylococcus aureus from cultures of various clinical samples. Methods: 322 clinical specimens of various natures were studied: suppurations (n = 126), upper and lower respiratory tract secretions (n = 54), faecal samples (n = 31), blood cultures with mixed Gram strains (n = 30), nasal samples (n = 41), urines (n = 20), catheters (n = 8) and others (n = 12). All samples were isolated on SaSelect (incubation 24 h) and MSA (incubation time: 24 and 48 h). The identification of pink colonies on SaSelect and colonies with a yellow halo on MSA was confirmed by a slide coagulase test. Results: Most clinical samples were polymicrobial. 152 samples contained S. aureus with SaSelect (24 h of incubation) and 144 with MSA (48 h of incubation). 153 S. aureus were isolated on either medium. Specificity and sensitivity were calculated, considering that a sample was positive if any of the two tested media showed the presence of S. aureus. When only the pink colour of the colonies at 24 h of incubation on SaSelect was taken as a criterion of identification for S. aureus, the specificity (100%) was similar to that obtained on MSA combined with coagulase test at 24 and 48 h of incubation (99.4%). The sensitivity values were different. At 24h, the sensitivity was 90.8% for MSA and 98% for SaSelect. At 48 h incubation time, the sensitivity determined on MSA increased to 94.7%. Conclusion: The sensitivity and specificity of the SaSelect medium were close to 100% in our study. This medium can be used in routine for the identification of S. aureus on the basis of the pink colour of the colonies without requiring a complementary coagulase test for confirmation. SaSelect makes it possible to reduce the cost of the test and the working time. P1605 Comparison of three chromogenic media for rapid detection of methicillin-resistant Staphylococcus aureus from screening swabs in hospitalised patients C. Nonhoff, O. Denis, A. Brenner, P. Buidin, C. Thiroux, M. Struelens (Brussels, BE) Objectives: To evaluate the performance of MRSA-ID (bioM´ erieux), MRSA Chromogenic Agar (MRSA-Screen, Oxoid) and MRSA-Select (Bio-Rad) media for detection of methicillin-resistant Staphylococcus aureus (MRSA) in muco-cutaneous swab samples from patients admitted to a 860-bed teaching hospital. Methods: Hospitalised patients (n = 639) were screened for MRSA carriage by sampling swabs from nares (n = 726), throat (n = 116), perineum (n = 109 and skin (n = 51). Swabs were inoculated into nutrient broth (SB) supplemented with 7.5% NaCl, MRSA-ID, MRSA-Screen and MRSA-Select agar at 35ºC. SB broths were sub-cultured after 24 h onto the three chromogenic media. S. aureus isolates were identified by coagulase test. Susceptibility to oxacillin was determined by cefoxitin disk method according to CLSI. Identification and oxacillin resistance were confirmed by PCR for 16S rRNA, nuc and mecA genes. Results: MRSA strains were isolated from 68 (6.8%) specimens from 45 patients: nares (n = 28), throat (n = 16), perineum (n = 13), skin (n = 11). Performance results of the three chromogenic media are shown in Table 1. Seven (10.8%) MRSA isolates grew only on primary agar plates while 10 (15.4%) were only isolated after the enrichment procedure. The specificity of MRSA-Screen decreased after 36 h incubation and with the enrichment step because of growth of pigmented methicillin-susceptible S. aureus (MSSA) (23 and 24 isolates, respectively). Sensitivity (%) Specificity (%) Medium 16-18 h 36 h Enrichment 16-18 h 36 h Enrichment MRSA-ID 45.6 75.0 85.3 100 99.9** 99.8 MRSA-Screen 44.1 80.9* 85.3 99.4 97.5** 97.4 MRSA-Select 45.6 72.1* 85.3 100 100** 100 *p = 0.045; **p < 0.001 Conclusion: The three chromogenic media demonstrated equivalent performance after 16-18 h. The use of an enrichment broth was necessary to optimise sensitivity but was associated with decreased specificity for MRSA-ID and MRSA-Screen. In this study, we observed equivalent sensitivity after 16-18h and marginal difference in sensitivity after 36h between the three media but significant lower specificity for MRSA-Screen after 36 h and enrichment (p < 0.001). P1606 In vitro evaluation of MRSA screening methods S. B¨ ocher, R. Smyth, G. Kahlmeter, R. Leo Skov (Copenhagen S, DK; V¨ axj¨ o, SE) Objectives: Chromogenic agars for detection of MRSA carriers are now widely available. Enrichment broths have been shown to increase