Staphylococci

• All cocci are gram-positive, except Neiserria, Veillonella and Branhamella
• • Micrococcus, Stomatococcus, and Planococcus are rarely isolated in human infections
• Micrococcus - catalase (+), non-motile cocci that occurs in pairs
• Micrococcus - usually present in air, dust, water, and skin
• M. cerebrosus, M. luteus, M. roseus - included in species of micrococcus
• Gram stain appearance of Micrococcus species

  
• Staphylococcus - non-motile, organisms that usually occur in irregular grape-like clusters
• Staphylococcus - Aerobic and Facultatively anaerobic
• Staphylococcus - able to grow most rapidly at 37C best room tempt. 20-25C
• Micrococcus - + strict aerobe
• Oxidizer - glucose utilization of Micrococcus
• Fermenter - glucose utilization of staphylococcus
• Modified oxidase test - this method is use to differentiate staph from micrococcus spp. by detection of the enzyme oxidase
• Reagent - tetramethyl-p-phenylenediamine dihydrochloride in DSMO
• negative (-) result : no color change
• Positive (+) result : blue-purple
• DMSO - enables the reagent to penetrate the cell wall
• Staphylococci - are susceptible to furazolidone, producing zone diameters that are 15mm
• Micrococci - are resistant to furazolidone, but small zone diameters (up to 9mm) may be seen
• S. aureus - the principal pathogen of the genus
• CoNS - Coagulase-Negative Staphylococci
• S. epidermidis - normal flora of the skin but mostly associated with hospital acquired infections
• S. saprophyticus - associated with UTI in young women
• Other CoNS - S. warneri, S. capitis, S. simulans, S. hominis, S. schleiferi, S. haemolyticus, S. psudintermidius
• S. aureus - grows well on most routine culture media like NA and TSA
• S. aureus - sheep's blood is recommended for primary isolation
• S. aureus - a zone of B Hemolysos is seen on sheep's BAP
• All cocci are catalase + except streptococcus
• • Staphylococcus - primary medical important
• Catalase-positive - enzyme that seperates strept to staph
• Micococcus - resistant to Lysostaphin (200 g/L)
• Micococcus - resistant to Lysostaphin (200 g/L)
• Furazolidone - Resistant to Micococcus
• Teichoic acid - contains polyribitol phosphate in CW
• Peptidoglycan - protects the organism from lysis
• Protein A - specific antigen unique to S. aureus
• Clumping factor - component of CW responsible for clumping the whole staphylococci in the presence of plasma
• Capsular Polysaccharide - the outer most layer responsible for virulence
• Heat stable enterotoxins - Enterotoxin A,B,C,D,E,H,I,J
• Enzyme - Catalase, DNAse, Lipase, Protease, Gelatinase, Hyaluronidase+, Staphylokinase ++, Penicillinase, Coagulase, Staphylocoagulase.