A selective and differential chromogenic medium for the qualitative direct detection of<unk> <unk>  resistance to oxacillin being tested. The top S.<unk>  isolate is a control that is not resistant to oxacillin; the other three isolates are<unk> -positive. Mueller–Hinton agar showing<unk>  resistant to an oxacillin disk Diagnostic microbiology laboratories and reference laboratories are key for identifying outbreaks of<unk> . Normally, a bacterium must be cultured from blood, urine, sputum, or other body-fluid samples, and in sufficient quantities to perform confirmatory tests early-on. Still, because no quick and easy method exists to diagnose<unk> , initial treatment of the infection is often based upon "strong suspicion" and techniques by the treating physician; these include quantitative PCR procedures, which are employed in clinical laboratories for quickly detecting and identifying<unk>  strains. Another common laboratory test is a rapid latex agglutination test that detects the PBP2a protein. PBP2a is a variant penicillin-binding protein that imparts the ability of S.<unk>  to be resistant to oxacillin. Microbiology Like all S.<unk>  (also abbreviated SA at times),<unk> -resistant S.<unk>  is a Gram-positive, spherical (coccus) bacterium about 1 micron in diameter. It does not form spores and it is not motile. It is frequently found in grape-like clusters or chains. Unlike<unk> -susceptible S.<unk>  (MSSA),<unk>  is slow-growing on a variety of media and has been found to exist in mixed colonies of MSSA. The mecA gene, which confers resistance to a number of antibiotics, is always present in<unk>  and usually absent in MSSA; however, in some instances, the mecA gene is present in MSSA but is not expressed. Polymerase chain reaction (PCR) testing is the most precise method for identifying<unk>  strains. Specialized culture media have been developed to better differentiate between MSSA and<unk>  and, in some cases, such media can be used to identify specific strains that are resistant to different antibiotics. Other strains of S.<unk>  have emerged that are resistant to oxacillin, clindamycin, teicoplanin, and erythromycin. These resistant strains may or may not possess the mecA gene. S.<unk>  has also developed resistance to vancomycin (VRSA). One strain is only partially susceptible to vancomycin and is called vancomycin-intermediate S.<unk>  (VISA). GISA, a strain of resistant S.<unk> , is glycopeptide-intermediate S.<unk>  and is less suspectible to vancomycin and teicoplanin. Resistance to antibiotics in S.<unk>  can be quantified by determining the amount of the antibiotic that must be used to inhibit growth. If S.<unk>  is inhibited at a concentration of vancomycin less than or equal to 4 μg/ml, it is said to be susceptible. If a concentration greater than 32 μg/ml is necessary to inhibit growth, it is said to be resistant.
Methicillin-resistant Staphylococcus aureus
Vancomycin-resistant Staphylococcus aureus
Vancomycin-resistant Enterococcus
Streptococcus bovis
Carbapenem-resistant enterobacteriaceae
Streptococcus pyogenes
Staphylococcus haemolyticus
Corynebacterium diphtheriae