Staphylococcus Flashcards
Name important species of genus Stapholococcus (3)
Staphylococcus aureus
Staphylococcus intermedius
Staphylococcus epidermidis
Where can Staphylococcus be found?
Skin of animals and man
Mucus membranes of upper respiratory and urogenital tract
Transient microflora in digestive tract
What kind of infections can opportunistic pathogens of Staphylococcus cause?
Pyogenic infections
What can predispose development of infection with staphylococcus?
Minor skin tissue trauma
Immunosuppression
Pathogenic species of Staphylococcus
St. aureus
St. intermedius
St. Hyicus
They are coagulase positive
Staphylococcus aureus causes
Abscesses
Pyogenic infections
Mastitis
Dermatitis
Staphylococcus intermedius causes (in dogs)
Pyoderma
Pustular dermatitis
Pyometra
Otitis externa
In dogs
Staphylococcus hyicus causes
Exudative dermatitis and septic artritis in pigs.
Mastitis in cattle
Apathogenic or facultative pathogenic species of Staphylococcus
St. epidermidis
St. saphrophyticus
They are coagulase negative
Staphylococcus that are coagulase positive (6)
St. aureus
St. intermedius (dogs, cats, cattle)
St. hyicus (pigs, cattle)
St. aureus subsp. anaerobius (sheep)
St. delphini
St. schleifen subsp. coagulans (dogs)
Virulence factors of Staphylococcus
Toxins: enterotoxin A-E, exfoliatin A and B, TSS toxin 1, epidermolytic toxins, pyogenic exotoxin, haemolysins a-y, leucocidin and protein A.
Enzymes: Staphylokinase, coagulase, hyaluronidase, lipase, collagenase, penicillinase, protease, nuclease, urease
Which virulence factor causes Staphylococcus-Scalded-Skin-Syndrome?
Exfoliatin B
Microscopical examination of Staphylococcus
Gram +
Non-motile
Small or medium size
Bundles of ‘‘grape’’ arrangement
Material for cultivation of Staphylococcus
Exudates, pus from abscess, milk, swab from skin, urine, tissues
Cultivation properties of Staphylococcus
S form
Facultative anaerobes
37 degrees Celsius (18-40C)
24 hours
Staphylococcus on meat-peptone-broth
Homogenous turbidity
Staphylococcus on meat-peptone-agar
S form
St. aureus have golden yellow pigment
Staphylococcus on blood agar
St. aureus and St. intermedius have a- and b-hemolysins = double haemolysis.
St. hyicus is without haemolysis
Special agar for Staphylococcus
Baird-Parker agar
Mannitol salt agar
Staphylococcus on Baird-Parker agar
Isolation and detection of Staphylococci.
Black (reduction of tellurite), shiny colonies surrounded by clear zones (egg yolk reaction).
Staphylococcus on mannitol salt agar
St. aureus tolerates high concentrations of NaCl (more than 15% - halophilic)
Which agar is used to differentiate pathogenic Staphylococci?
Maltose agar
Staphylococcus species on maltose agar (3)
St. aureus - utilize maltose, yellow colonies (+), aerobic and anaerobic conditions
St. intermedius - poor maltose fermenter, pink colonies, aerobic conditions
St. hyicus - doesn’t ferment maltose, purple colonies (-)
Staphylococcus reaction to catalase and oxidase:
Catalase +, oxidase -
Describe coagulase test with Staphylococci
Staphylococci are mixed with rabbit plasma, fibrinogen is converted to fibrin by coagulase
Which test is used for detection of DNase production?
DNase test (on DNase agar)
Special examination for Staphylococci:
Commercial tests - Staphytest, Staphy-slide test
Serological - cell wall antigens
DNA methods
Enterotoxins - immunodiffusion, ELISA, PCR
Antibiotic susceptibility test for Staphylococcus
Enzyme penicillinase (b-lactamase) is plasmid encoded and show frequent resistance to b-lactam ATP (PNC).
MRSA - Methicillin-Resistant-St.aureus = multiresistance to ATB
