Question | Answer |
what are some morphological characteristics of staph? | gram positive spherical, spore forming, facultative anaerobes. they ferment a wide variety of sugars but no gas, grow on most lab media if supplemented with AAs and vit B, grow in presence of high [NaCl] |
how many types of staph are there and how many are associated with disease? | more than forty kinds, only three associated with disease |
which types of staph have coagulase | staph. aureus |
which staph have white colored colonies | staph epidermidis, staph saprophyticus |
which types of staph have S novobiocin? | staph aureus and staph epidermidis |
which type of staph has golden yellow colonies? | staph aureus |
which type of staph has R novobiocin? | staph saprophyticus |
which structural virulence factor is associated with the shape and rigidity of the cell? it serves as a chemoattractant for leucocytes, activates complement | peptidoglycan |
this structural virulence factor are polymers of ribotol or glycerol phosphates. resp for adherence and in deep seated infections | teichoic acids |
this structural virulence factor is embedded in the cell wall and has an anti-opsonin effect: binds to Fc portion of IgG and leaves Fab portion free to bind with specific antigen | protein A |
this structural virulence factor promotes binding to mucosal cells | ribronectin binding protein (FnBP) |
this structural virulence factor is made up of mostly polysaccharides and is antiphagocytic | capsule |
what are some toxins and enzymes on staph? | coagulase (free and bound and thought to cause abscesses), hemolysins (alpha, beta, gamma, delta), leukocidin (penton valentine, LukGH), |
what is a toxin of interest in MRSA? | LukGH |
what is another virulence factor of interest on staph? | PVI |
this toxin hydrolyzes hydrogen peroxide into tap water and oxygen. it's the primary test to separate staph from strep | catase |
this toxin catalyzes the hydrolysis of hyaluronic acid | hyaluronidase |
this toxin dissolves fibrin clots | staphylokinase (fibrinolysin) |
this toxin hydrolyzes lipids and ensures survival on the skin and sebaceous glands | lipase enzymes |
this toxin is carried by the mecA gene and breaks the beta lactam ring | beta lactamase |
this toxin exfoliates the epidermis from dermis and is in scalded skin syndrome and bullous impetigo | exfoliative toxins A and B |
this toxin is involved with fever, rash, hypotension, and peeling of the skin upon recovery | toxin shock syndrome toxin (TSST-1) |
this toxin resists gut enzymes and low pH, found in thirty to fifty percent of strains, most common kind of food poisoning in the US, and ingestion causes vomitting and diarrhea within two to six hours. it behaves as a superantigen | enterotoxin |
these glom to the sides of the binding site and gum up the system. as a result, T cells go on an unregulated rampage with up to twenty percent of the T cells responding and uncontrollably releasing regulatory molecules, such as IL2, interferon gamma, TNF. | superantigens |
how do strep encounter the body | through normal skin flora |
how do staph enter the body | they cannot penetrate the skin. enter through nares and mucous membranes |
what is the primary pathophysiology of bacteremia? | it goes through the lymphatics and then spreads to the vascular system. this is how abscesses spread. |
what is an example of a disease where an abscess spreads via the lymphatics to the blood stream | bacteremia |
what is an example of a disease where an abscess spreads metastatically to other parts of the body? | osteomyelitis |
what are some skin and soft tissue infetions caused by staph aureus? | immpetigo(Bullous), furuncles, wound infections, cellulitis |
what are some CNS diseases caused by staph. aureus? | brain abscesses, epidural abscesses? |
what are some musculoskeletal diseases caused by staph aureus? | osteomyelitis, arthritis |
what are some toxin mediated diseases caused by staph? | TSS, scalded skin syndrome, food poisoning |
what are some primary skin infections of staph? | impetigo, scalded skin syndrome, TSS, folliculitis, abscesses, boils, carbuncles, cellulitis |
this is a disease seen in children where the vesicles enlarge to form flaccid bullae with clear yellow fluid, which later become darker and more turbid. its due to a strain of staph. a that produces toxin A | bullous impetigo |
what other disease is caused by exfoliative toxins A and B? | scalded skin syndrome |
an abscess formation in the skin is called this | furuncle or boil |
when staph aureus spreads to subcutaneous tissue, it develops into this | cellulitis |
what are some mechanisms of resistance to penicillin? | beta lactamase, altered pbp |
generally what AB's do u treat MRSA with? | trimethoprim, sulfamethaxazone, doxycycline, or clindamycin if susceptible |
what are some risk factors for developing MRSA? | hospitalization, cathaterization, surgery, crowded living spaces, taking drugs by injection, incarcerated people, contact sports |
this staph disease infects prosthetic joints, IV catheters, and heart valves. | staph epidermidis |
this type of staph causes UTI infection in females | staphylococcus saprophyticus |
what are two strain characterization that can be used for epidemiologic studies? | phage typing, DNA sequencing. |
which type of staph does mannitol fermentation? | staph aureus |