Abstract:
A monoclonal or polyclonal antibody specific for an epitope common to  Staphylococcus aureus  strains of various capsular serotypes, particularly methicillin-resistant strains, the antibody being selected from immunoglobulins G, M, and A, and the use thereof in a reagent for detecting  Staphylococcus aureus.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of the detection of  Staphylococcus aureus  bacteria, and in particular strains of  Staphylococcus aureus  which are resistant to methicillin. 
     DESCRIPTION OF RELATED ART 
     “Detection” is understood to mean collectively all the techniques which make it possible to identify, qualitatively and/or quantitatively, or to enrich, purify or separate a biological analyte, in this case  Staphylococcus aureus  bacteria. 
     In accordance with the document EP-A-0 323 331, a reagent for detecting  Staphylococcus aureus  bacteria, including the methicillin-resistant strains, is known, this reagent comprising: 
     fibrinogen, 
     an antibody recognized by  Staphylococcus aureus  protein A, 
     an antibody specifically recognizing the type 5 capsular serotype of  Staphylococcus aureus  or an antibody specifically recognizing the type 8 serotype of  Staphylococcus aureus , and preferably a mixture of these two antibodies. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a monoclonal or polyclonal antibody is provided which specifically recognizes an epitope common to  Staphylococcus aureus  strains of various capsular serotypes, particularly the methicillin-resistant strains. This antibody is selected from the type G immunoglobulins, the type M immunoglobulins and the type A immunoglobulins. 
     A particularly advantageous application of the antibody according to the invention consists in incorporating it into a reagent specific for the detection of  Staphylococcus aureus , including the methicillin-resistant strains. Compared with the document EP-A-0 323 331, the sensitivity of the reagent of the invention is superior, because the capacity for recognition of the capsular serotypes is greater. 
     Thus, according to the invention, there are provided and described: 
     a monoclonal or polyclonal antibody specific for an epitope common to the  Staphylococcus aureus  strains of various capsular serotypes, particularly the methicillin-resistant strains, the said antibody being selected from the type G immunoglobulins, the type M immunoglobulins and the type A immunoglobulins; this antibody specifically recognizes at the same time at least two different capsular serotypes of the said  Staphylococcus aureus  strains; preferably, it is selected from the type G immunoglobulins and the type M immunoglobulins; 
     a monoclonal or polyclonal antibody as defined above which in particular recognizes at least the type 5 capsular serotype and the type 8 capsular serotype of the said  Staphylococcus aureus  strains, 
     a monoclonal antibody capable of being obtained according to a technique adapted from Galfre et al. (Nature, 266, 550-552, (1977)), using as initial cell line for the fusion, the myeloma line SP2/0-Ag14 (ATCC CRL 1581); the fusion is performed with spleen cells from mice of the BALB/C species and of the BALB/CBYJICO strain (marketed by the company IFFA Credo), immunized with a  Staphylococcus aureus  type 5 strain, according to conventional techniques; the clones obtained were screened by immunoenzymatic techniques (ELISA); the selected clones were reinjected by the intraperitoneal route into mice prepared beforehand for the production of ascitic fluid; each monoclonal antibody was used to sensitize latex particles and was tested for its specificity to recognize  Staphylococcus aureus  capsular polysaccharides; the monoclonal antibodies called P2G7A1E5 and P6D8D12E1 respectively were selected because of their specificity in recognizing an epitope common to various capsular serotypes, in particular of types 5 and 8; 
     a monoclonal antibody capable of being obtained, or as obtained from the hybridoma cell line deposited under the No. 96021514, on Feb. 15, 1996 with the ECACC; 
     a monoclonal antibody capable of being obtained, or as obtained from the hybridoma cell line deposited under the No. 96021513, on Feb. 15, 1996 with the ECACC; 
     a hybridoma cell line such as deposited under the No. 96021514, on Feb. 15, 1996 with the ECACC, or such as that deposited under the No. 96021513, on Feb. 15, 1996 with the ECACC, or any other derived hybridoma cell line, for example any progeny of this line; the cell lines are claimed as such, as well as any derived cell line, that is to say capable of producing antibodies exhibiting the same immunological characteristics as those described in the present invention; 
     a specific reagent for the detection of  Staphylococcus aureus  bacteria and particularly methicillin-resistant strains, comprising at least one antibody specifically recognizing at least one epitope common to the various capsular serotypes of the methicillin-resistant  Staphylococcus aureus  strains, the said reagent comprising at least one monoclonal or polyclonal antibody as defined above; the said antibody can be attached or coupled, or otherwise, to a support or a marker; monoclonal or polyclonal antibody is understood to mean the antibodies as defined above as well as any antibody exhibiting cross-specificity with the latter; 
     a specific reagent, particularly for the detection of  Staphylococcus aureus  bacteria and particularly of methicillin-resistant strains, comprising in addition fibrinogen or a compound based on fibrinogen, capable of being recognized by the  Staphylococcus aureus  affinity factor for fibrinogen; the fibrinogen or fibrinogen compound can be attached or coupled, or otherwise, to a support or to a marker; 
     a specific reagent, particularly for the detection of the bacteria  Staphylococcus aureus  and particularly for the methicillin-resistant strains, comprising in addition immunoglobulins or their Fc fragment recognized by  Staphylococcus aureus  protein A, attached or coupled, or otherwise, to a support or to a marker. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     All sorts of support or marker can be envisaged according to the invention. 
     Particles in suspension can thus be used. These particles are in particular latex particles such as polystyrene beads or similar particles, preferably having a size of less than 2 μm. By way of example, there may be mentioned Estapor particles, marketed by the company RHONE-POULENC, such as: 
     polystyrene K080 particles having a diameter of 0.8 μm, 
     polystyrene K109 particles having a diameter of 0.8 μm, 
     polystyrene particles having carboxyl groups, PSI 480, having a diameter of 0.8 μm. 
     Magnetic gels, such as polyacrylamide and/or agarose gels containing magnetic particles can also be used. It is possible, in addition, to use gels such as Ultrogel and Magnogel (trademarks) from the company IBF. 
     The support used in a reagent according to the present invention may also be red blood cells, for example from sheep. 
     The support may be in the form of a plate, a cone, a strip, for example made of polystyrene or a styrene-based copolymer, a glass tube or the like. 
     The attachment of antibodies and of fibrinogen to particles in suspension, particularly of latex, may be achieved according to one of the following techniques: 
     by passive adsorption, it being possible for the attachment to be spontaneous, during incubation of the latex particles in a solution containing the antibodies and the fibrinogen; an incubation for example of about 2 hours at 20° C. is often sufficient; 
     by covalent bonding, it being possible for the attachment to be achieved by creating a covalent bond between the antibodies and the reactive groups present on some latex particles; it is possible for example to use a carbodiimide to create the covalent bond. 
     When the support consists of red blood cells, these may be sensitized beforehand with fibrinogen or any other appropriate molecule, according to conventional techniques. 
     The concentration of antibodies to be attached onto the latex particles, which should be determined for each antibody according to known methods, is usually between 0.1 μg and 100 μg of antibody proteins per millilitre of latex in solution. 
     In a reagent according to the invention, the antibodies and the fibrinogen may be attached onto a single suspension of particles, for example of latex, or alternatively may be attached onto suspensions of particles which are respectively different, such as red blood cells and latex particles, or various latexes which are then mixed in order to constitute the reagent. 
     The marker may be any biological or chemical molecule, for example an enzyme, a hapten, an oligonucleotide, a radioactive element and the like. 
     Other subjects of the invention are the following: 
     a reagent as defined above comprising an immunoglobulin-type antibody comprising an Fc fragment capable of attaching onto  Staphylococcus aureus  protein A and/or another compound based on fibrinogen or derivative, capable of reacting with the affinity factor for fibrinogen of the said bacteria, the said reagent further comprising at least one polyclonal or monoclonal antibody capable of specifically recognizing various capsular serotypes of  Staphylococcus aureus , particularly types 5 and 8 serotypes; 
     a process for detecting in a biological sample  Staphylococcus aureus  bacteria, and particularly methicillin-resistant strains, characterized in that: 
     a reagent as defined above is made available, 
     the said sample is brought into contact with the said reagent, 
     the production of agglutination is observed. 
    
    
     The characteristics and advantages of the subjects of the invention are stated and illustrated below in Examples 1-3. 
     EXAMPLE 1 
     Composition of a Reagent According to the Invention, Called SLIDEX STAPH PLUS 
     The reagent comprises an immunoglobulin-type antibody comprising an Fc fragment capable of attaching onto  Staphylococcus aureus  protein A and/or another compound based on fibrinogen or derivative, capable of reacting with the affinity factor for fibrinogen of the said bacteria, the said reagent further comprising at least one polyclonal or monoclonal antibody capable of specifically recognizing various capsular serotypes of  Staphylococcus aureus , particularly types 5 and 8 serotypes. 
     EXAMPLE 2 
     Process for the Production of the Antibody Contained in the Reagent of Example 1 
     a) Preparation of spleen cells from mice immunized with a  Staphylococcus aureus  strain 
     Material: 
       Staphylococcus aureus  strains CIP103313 of capsular serotype 5 and CIP108314 of capsular serotype 8. 
     Culture medium: Columbia agar+5% sheep blood. 
     Method: 
     The strains preserved at −80° C. are cultured twice on sheep blood agar. 
     The colonies are suspended in physiological saline at the concentration of 3×10 9  microorganisms/ml. 
     A method of inactivation was used: inactivation at 70° C. for 1 hour. 
     The vaccines are freshly prepared. 
     Origin of the cell culture: 
       Staphylococcus aureus  strain of capsular serotype 5 
     Animal for immunization: female mice of the BALB/C species and of the BALB/CBYJICO strain (provided by IFFA Credo) 
     Myelomatous line SP2/0-AG14. 
     Immunization protocol: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 J = 0 
                 3 × 10 8  microorganisms + CFA (1:1) 
                 IP 
               
               
                   
                 J = 7.14 
                 3 × 10 8  microorganisms 
                 IP 
               
               
                   
                 J = 28.76 
                 3 × 10 8  microorganisms 
                 IP 
               
               
                   
                 J = 204 
                 Booster 3 × 10 8  microorganisms in 
                 IV 
               
               
                   
                   
                 9% NaCl 
               
               
                   
                 J = 207 
                 Fusion of 29/01/93, mouse No. 1 series 010 
               
               
                   
                   
               
             
          
         
       
     
     Culture in suspension 
     Ploidy: heteroploid 
     Culture conditions: 
     Basic medium: Iscove&#39;s Modified Dulbecco Medium supplemented with sodium bicarbonate (3024 mg/l), 10% foetal calf serum (FCS), PH 6.7 to 7.3, temperature 25° C. 
     Additional reagents: insulin (5 μg/l), 2-mercaptoethanol (10 μM), ethanolamine (20 μM), penicillin (100 U/ml), streptomycin (50 μg/ml). 
     Subculturing technique: the cells are subcultured every 2 or 3 days. 
     Freezing of the cells: 
     Composition of the medium: IMDM supplemented with 10% FCS and 10% DMSO (dimethyl sulphoxide—Sigma) 
     Cellular concentration: 3.6×10 6  cells per ampoule (2×10 6  cells/ml) 
     Method: slow freezing of the cells at −80° C. in IMDM medium—10% FCS—10% DMSO, 24 h to 72 h, then storage in liquid nitrogen −180° C. 
     b) Identification of the stable hybridoma 
     Number of clonings carried out: 2 
     Name of the clone : 6D8D12El 
     Isotyping: IgG2b,K 
     Synthesis capacity: level of Ig&#39;s secreted into the supernatant: ND. 
     Antigenic specificity: 
     Indirect ELISA (1) 
     NUNC-maxisorb plates coated with 50 μl of STAPH 5 microorganisms (10 9  g/ml), dried overnight at 37° C., 
     saturate with 100 μl of PBS-milk 1% for 1 h at 37° C., 
     saturate with 100 μl of PBS-horse serum 1%, incubate for 1 h at 37° C., 
     add 100 μl of supernatant or of ascitic fluid diluted in PBS-Tween 20 0.05%, and then incubated 1 h at 37° C., 
     add 100 μl of Ig&#39;s anti-mouse Ig(H+L) conjugated to ALP (Jackson Laboratories batch 24724) diluted 1/2000 in PBS-BSA 1% +horse serum 1%, 1 h at 37° C., 
     add 100 μl of PNPP (BioMérieux ref. 60002990) at the concentration of 2 mg/ml in DEA-HCL (Biomérieux ref. 60002989), pH 9.8, incubated 30 min at 37° C., 
     block the reaction with 100 μl of 1 N NaOH. 
     NB: 3 washes are performed between each step with 300 μl of Pbs-tween 20 0.05% and an additional wash with distilled water before adding the PNPP. 
     RESULTS of (1): this antibody is specific for  S. aureus  and does not recognize either  S. Warneri, S. Hominis, S. Epidermidis, S. Cohnii  or  S. Haemolyticus.    
     It recognizes the  S. aureus  type 5, type 8, type B, type A and type MC31, and the non-5 and non-8 strains (Ex: strains 1033, K8, 16N15). 
     Direct agglutination technique (2) 
     In round-bottomed plates (Biomérieux M220 24A ref. 96350), place 50 μl of supernatants diluted in PBS +50 μl of microorganisms at 5×10 8  g/ml; stir the plates and then incubate at 22° C. The reading is performed by eye, about 15 hours later. 
     RESULTS of (2): agglutination visible by eye (4+). 
     c) Production of antibodies in vivo 
     Animal used: female mice 4-6 weeks old, of the BALB/C species, of the BALB/CBYJICO strain (IFFA Credo). 
     Preparation of inoculum: the cellular suspension is centrifuged at 200 g, 10 minutes, 25° C. The cells are resuspended in 9% NaCl in an amount of 10 6  cells/ml, 
     Injection of 10 6  cells/mouse by the intraperitoneal route, for 20 mice, 
     Time of harvesting the ascitic fluid: 10 days+2 days, 
     Volume of ascites: 245.5 ml, 
     Volume of the pool: 230.5 ml, 
     Yield: 93.9%, 
     EXAMPLE 3 
     Comparison of the Sensitivity and of the Specificity of the SLIDEX STAPH PLUS Reagent and of Those of Various Commercialized Reagents, in the Detection of Various  Staphylococcus aureus  Strains 
     The SLIDEX STAPH PLUS reagent was compared with the following reagents: 
     SLIDEX STAPH KIT: ref. 7 311 2 batch 674145 B (exp. April 1996), marketed by the Applicant, 
     STAPHYSLIDE: ref. 5 508 1 batch 674775 A (exp. September 1996), marketed by the Applicant, 
     PASTOREX STAPH PLUS marketed by Diagnostic Pasteur: ref. 56356 batch 4LO42R (exp. February 1996) and batch SE 047 R (exp. July 1996), 
     STAPHAUREX PLUS marketed by Murex: ref. ZL 33 batch K61691 0 (exp. Jan. 1, 1995) and batch K9251 1 0 (exp. August 1996). 
     To determine the sensitivity of each of these reagents, the following 346  Staphylococcus aureus  strains were tested: 
     118  S. aureus  strains resistant to methicillin and not having the affinity factor for fibrinogen (Clumping Factor negative) (origin: France, Germany, England, Benelux, Italy, Spain, USA, USA Kansas) 
     131  S. aureus  strains resistant to methicillin and having the affinity factor for fibrinogen (Clumping Factor positive) (origin: France, Germany, England, Benelux, Italy, Spain, USA, Australia, Hong Kong) 
     97 methicillin-sensitive  S. aureus  strains (origin: France, England, Benelux, Italy, Spain, Poland, Australia, Hong Kong) 
     In addition, to determine the specificity of each of these reagents, 155 Staphylococcus non-aureus strains were tested (origin : France, Germany, England, Benelux, Italy, Spain, Poland, USA, Australia, Hong Kong). 
     The strains were cultured on Columbia agar+5% sheep blood. 
     a) Sensitivity results obtained with the 118  S. aureus  strains resistant to methicillin and not having the affinity factor for fibrinogen 
     The results are assembled in Table 1 below: 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Number of 
                 Slidex 
                 Slidex 
                 Pastorex 
                 Staphaurex 
               
               
                 strains 
                 Staph Plus 
                 Staph Kit 
                 Staph Plus 
                 Plus 
               
               
                   
               
             
             
               
                 76  
                 + 
                 + 
                 + 
                 + 
               
               
                 1 
                 + 
                 + 
                 + 
                 unint. 
               
               
                 1 
                 + 
                 + 
                 unint. 
                 + 
               
               
                 1 
                 + 
                 + 
                 − 
                 + 
               
               
                 9 
                 + 
                 + 
                 + 
                 − 
               
               
                 4 
                 + 
                 + 
                 − 
                 − 
               
               
                 18  
                 + 
                 − 
                 + 
                 + 
               
               
                 1 
                 + 
                 − 
                 + 
                 − 
               
               
                 5 
                 + 
                 − 
                 − 
                 − 
               
               
                 1 
                 − 
                 + 
                 + 
                 + 
               
               
                 1 
                 − 
                 + 
                 − 
                 − 
               
               
                 total: 
                 116 
                 94 
                 106 
                 97 
               
               
                 118 
               
               
                 Sensitivity 
                 98.30% 
                 79.67% 
                 90.6% 
                 82.9% 
               
               
                   
               
               
                 unint. means “uninterpretable”.  
               
             
          
         
       
     
     In accordance with Table 1, SLIDEX STAPH PLUS showed a significantly greater sensitivity (98.30%) than that of SLIDEX STAPH KIT (79.67%), PASTOREX STAPH PLUS (90.6%) and STAPHAUREX PLUS (82.9%). 
     b) Results obtained with the 131  S. aureus  strains resistant to methicillin and having the affinity factor for fibrinogen 
     The results are assembled in Table 2 below: 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Number of 
                 Slidex 
                 Slidex 
                 Pastorex 
                 Staphaurex 
               
               
                 strains 
                 Staph Plus 
                 Staph Kit 
                 Staph Plus 
                 Plus 
               
               
                   
               
             
             
               
                 123  
                 + 
                 + 
                 + 
                 + 
               
               
                 2 
                 + 
                 + 
                 + 
                 unint. 
               
               
                 4 
                 + 
                 + 
                 + 
                 − 
               
               
                 2 
                  +* 
                 + 
                  +* 
                 − 
               
               
                 total: 
                 131 
                 131 
                 131 
                 123 
               
               
                 131 
               
               
                 Sensitivity 
                 100% 
                 100% 
                 100% 
                 95.35% 
               
               
                   
               
               
                 *slow agglutination  
               
               
                 unint. means “uninterpretable”.  
               
             
          
         
       
     
     c) Results obtained with the 97 methicillin-sensitive  S. aureus  strains 
     The results are assembled in Table 3 below: 
     
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Number 
                   
                   
                   
                   
                   
               
               
                 of 
                 Slidex 
                 Slidex 
                   
                 Pastorex 
                 Staphaurex 
               
               
                 strains 
                 Staph Plus 
                 Staph Kit 
                 Staphyslide 
                 Staph Plus 
                 Plus 
               
               
                   
               
             
             
               
                 94  
                 + 
                 + 
                 + 
                 + 
                 + 
               
               
                 1 
                 + 
                 unint. 
                 + 
                 + 
                 + 
               
               
                 2 
                 + 
                 unint. 
                 unint. 
                 + 
                 + 
               
               
                 total: 
                 97 
                 94 
                 95 
                 97 
                 97 
               
               
                 97 
               
               
                 Sensi- 
                 100% 
                 100% 
                 100% 
                 100% 
                 100% 
               
               
                 tivity 
               
               
                   
               
               
                 unint. means “uninterpretable”.  
               
             
          
         
       
     
     In accordance with this table, all the strains were detected, giving a sensitivity of 100% for each of the reagents. 
     d) Results obtained with the 155 S. non-aureus strains 
     The results are assembled in Table 4 below: 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Slidex Staph Plus 
                   
                 Slidex Staph Kit 
                   
                 Staphyslide 
               
             
          
           
               
                 Staphylococcus non-aureus (number) 
                 + 
                 − 
                 UNINT 
                   
                 + 
                 − 
                 UNINT 
                   
                 + 
                 − 
                 UNINT 
               
               
                   
               
               
                   S. epidermidis  (45) 
                 2 
                 43  
                 0 
                   
                 9 
                 25  
                 11  
                   
                 5 
                 30  
                 10  
               
               
                   S. simulans  (8) 
                 0 
                 8 
                 0 
                   
                 3 
                 5 
                 0 
                   
                 0 
                 8 
                 0 
               
               
                   S. hyicus  (3) 
                 1 
                 2 
                 0 
                   
                 0 
                 3 
                 0 
                   
                 0 
                 3 
                 0 
               
               
                   S. saprophiticus  (10) 
                 0 
                 9 
                 1 
                   
                 0 
                 9 
                 1 
                   
                 0 
                 9 
                 1 
               
               
                   S. haemolyticus  (20) 
                 0 
                 20  
                 0 
                   
                 8 
                 12  
                 0 
                   
                 0 
                 20  
                 0 
               
               
                   S. warneri  (12) 
                 0 
                 12  
                 0 
                   
                 3 
                 9 
                 0 
                   
                 0 
                 12  
                 0 
               
               
                   S. hominis  (14) 
                 0 
                 13  
                 1 
                   
                 7 
                 5 
                 2 
                   
                 2 
                 11  
                 1 
               
               
                   S. lugdunensis  (5) 
                 0 
                 5 
                 0 
                   
                 0 
                 5 
                 0 
                   
                 0 
                 5 
                 0 
               
               
                   S. schleiferi  (4) 
                 3 
                 1 
                 0 
                   
                 3 
                 1 
                 0 
                   
                 3 
                 1 
                 0 
               
               
                   S. cohnii  (4) 
                 1 
                 3 
                 0 
                   
                 3 
                 1 
                 0 
                   
                 0 
                 4 
                 0 
               
               
                   S. capitis  (3) 
                 0 
                 3 
                 0 
                   
                 0 
                 3 
                 0 
                   
                 0 
                 3 
                 0 
               
               
                   S. sciuri  (10) 
                 3 
                 7 
                 0 
                   
                 0 
                 8 
                 2 
                   
                 0 
                 8 
                 2 
               
               
                   S. lentus  (2) 
                 0 
                 2 
                 0 
                   
                 0 
                 2 
                 0 
                   
                 0 
                 2 
                 0 
               
               
                   S. xylosus  (2) 
                 0 
                 1 
                 1 
                   
                 0 
                 0 
                 2 
                   
                 0 
                 0 
                 2 
               
               
                   S. auricularis  (1) 
                 0 
                 1 
                 0 
                   
                 1 
                 0 
                 0 
                   
                 0 
                 1 
                 0 
               
               
                   S. chromogenes  (4) 
                 0 
                 4 
                 0 
                   
                 0 
                 4 
                 0 
                   
                 0 
                 4 
                 0 
               
               
                   S. caseolyticus  (1) 
                 0 
                 1 
                 0 
                   
                 0 
                 1 
                 0 
                   
                 0 
                 1 
                 0 
               
               
                   S. intermedium  (7) 
                 1 
                 2 
                 4 
                   
                 2 
                 4 
                 1 
                   
                 2 
                 5 
                 0 
               
               
                 Total (155) 
                 11  
                 137  
                 7 
                   
                 39  
                 97  
                 19  
                   
                 12  
                 127  
                 16  
               
             
          
           
               
                 Specificity 
                 137/148 
                   
                 97/136 
                   
                 127/139 
               
               
                   
                 92.57% 
                   
                 71.32% 
                   
                 91.37% 
               
               
                   
               
             
          
           
               
                   
                 Pastorex Staph Plus 
                   
                 Staphaurex Plus 
               
             
          
           
               
                   
                 Staphylococcus non-aureus (number) 
                 + 
                 − 
                 UNINT 
                   
                 + 
                 − 
                 UNINT 
               
               
                   
                   
               
               
                   
                   S. epidermidis  (45) 
                 1 
                 44  
                 0 
                   
                 2 
                 43  
                 0 
               
               
                   
                   S. simulans  (8) 
                 0 
                 8 
                 0 
                   
                 2 
                 6 
                 0 
               
               
                   
                   S. hyicus  (3) 
                 0 
                 3 
                 0 
                   
                 1 
                 2 
                 0 
               
               
                   
                   S. saprophiticus  (10) 
                 0 
                 9 
                 1 
                   
                 1 
                 8 
                 1 
               
               
                   
                   S. haemolyticus  (20) 
                 1 
                 19  
                 0 
                   
                 0 
                 20  
                 0 
               
               
                   
                   S. warneri  (12) 
                 0 
                 12  
                 0 
                   
                 0 
                 12  
                 0 
               
               
                   
                   S. hominis  (14) 
                 3 
                 10  
                 1 
                   
                 0 
                 13  
                 1 
               
               
                   
                   S. lugdunensis  (5) 
                 2 
                 3 
                 0 
                   
                 2 
                 3 
                 0 
               
               
                   
                   S. schleiferi  (4) 
                 3 
                 1 
                 0 
                   
                 3 
                 1 
                 0 
               
               
                   
                   S. cohnii  (4) 
                 2 
                 2 
                 0 
                   
                 1 
                 3 
                 0 
               
               
                   
                   S. capitis  (3) 
                 0 
                 3 
                 0 
                   
                 0 
                 3 
                 0 
               
               
                   
                   S. sciuri  (10) 
                 2 
                 6 
                 2 
                   
                 2 
                 5 
                 3 
               
               
                   
                   S. lentus  (2) 
                 0 
                 2 
                 0 
                   
                 0 
                 2 
                 0 
               
               
                   
                   S. xylosus  (2) 
                 1 
                 0 
                 1 
                   
                 1 
                 0 
                 1 
               
               
                   
                   S. auricularis  (1) 
                 0 
                 1 
                 0 
                   
                 0 
                 1 
                 0 
               
               
                   
                   S. chromogenes  (4) 
                 0 
                 4 
                 0 
                   
                 1 
                 3 
                 0 
               
               
                   
                   S. caseolyticus  (1) 
                 0 
                 1 
                 0 
                   
                 0 
                 1 
                 0 
               
               
                   
                   S. intermedium  (7) 
                 2 
                 2 
                 3 
                   
                 1 
                 4 
                 2 
               
               
                   
                 Total (155) 
                 17  
                 130  
                 8 
                   
                 17  
                 130  
                 8 
               
             
          
           
               
                   
                 Specificity 
                 130/147 
                   
                 130/147 
               
               
                   
                   
                 88.44% 
                   
                 88.44% 
               
               
                   
                   
               
             
          
         
       
     
     The  S. epidermidis, S. simulans, S. hyicus  species may have a capsule. 
     The  S. lugdunensis, S. schleiferi, S. hyicus, S. interrmedius  species may have the affinity factor for fibrinogen. 
     The specificities of PASTOREX STAPH PLUS and STAPHAUREX are identical (88.44%) but less than those of STAPHYSLIDE (91.37%) and of SLIDEX STAPH PLUS (92.57%). 
     e) Performances of the reagents 
     Table 5 below indicates the results of sensitivity and specificity of each of the reagents. 
     
       
         
               
               
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 5 
               
             
             
               
                   
                   
               
               
                   
                 SENSITIVITY 
                   
               
             
          
           
               
                   
                   S. aureus  meti R 
                   
               
             
          
           
               
                   
                 All the 
                   
                 All the 
                   
               
             
          
           
               
                   
                 Clumping Factor 
                 meti R 
                 
                   S. aureus 
                 
                 
                   S. aureus 
                 
                   
               
             
          
           
               
                 REAGENTS 
                 negative 
                 positive 
                 strains 
                 meti S 
                 strains 
                 SPECIFICITY 
               
               
                   
               
               
                 Slidex staph Plus 
                 98.30% 
                 100% 
                  99.2% 
                 100% 
                 98.84% 
                 92.57% 
               
               
                 Slidex staph kit 
                 79.67% 
                 100% 
                 90.36% 
                 100% 
                  93.0% 
                 71.32% 
               
               
                 Staphyslide 
                 0 
                 100% 
                 52.61% 
                 100% 
                  65.7% 
                 91.37% 
               
               
                 Pastorex Staph Plus 
                  90.6% 
                 100% 
                 95.56% 
                 100% 
                 96.81% 
                 88.44% 
               
               
                 Staphaureux Plus 
                  82.9% 
                 95.35%   
                 89.43% 
                 100% 
                 92.42% 
                 88.44% 
               
               
                   
               
             
          
         
       
     
     In this table, as in the following tables where they appear, the expressions meti R, meti S mean “methicillin-resistant” and “methicillin-sensitive” respectively. 
     It is evident from this table that the sensitivity of SLIDEX STAPH PLUS (99.2%) is significantly greater than the other reagents; this superiority is essentially due to a better performance on the  S. aureus  strains resistant to methicillin and not having the affinity factor for fibrinogen.