Staphylococcus Flashcards
Staph are all..
catalase positive
Gpos cocci in clusters
Staph groups
Staph aureus
Staph epidermidis
Staph saprophyticus
Staph aureus features
- basic habitat nares of nose
- produces yellow pigment
- beta-hemolytic
- coagulase positive (forms fibrin clots in plasma)
- catalase positive
- Protein A virulence factor (blocks Fc-IgG interaction preventing phagocytosis and complement activation)
- produces toxin related diseases
Staph aureus infections
- Toxin disease
- Toxic shock syndrome (TSST-1)
- Food poisoning (staph aureus enterotoxin)
- Scalded Skin Syndrome (Exfoliatin)
- Infectious diseases
- Skin infections (impetigo)
- Pneumonia
- Endocarditis
- Osteomyelitis
- Abscesses
Toxic shock syndrome
Toxin: TSST-1
fever
shock
red rash
diffuse red erythema (sun burn)
after weeks desquamation of palms and soles
diarrhea
tampons or surgical wound packing
Staph food poisoning
food handler contaminates food and often when food is left at room temp for several hours (picnic)
staph grows in food and makes enterotoxin (ingest pre-formed toxin to get sick)
illness develops 3-6 hours later
NV and abdominal cramps
multiple sick people
classic food is mayonaise (potatoe or egg salad)
Scalded skin syndrome
Staph Exfoliative toxin (exfoliatin)
occurs in newborns 3-7 days old
fever, diffuse erythema starting at the mouth
sloughing of skin (toxin destroys keritnocyte attachments in stratum granulosum only)
Damage in intraepidermal and heals completely without scarring
Nikolsky’s sign (skin slips off with gentle tug)
Bullous impetigo
Bullous type is caused by Staph aureus
honey colored crusted lesions
bullous impetigo is a variant of impetigo with bullae (fluid-filled sacs)
occurs in children and easily spread
S. aureus exfoliative toxin strains
Staph pneumonia
rare cause of lobar pneumonia
classically occuring as a post-infectious pneumonia (following influenza)
Staph endocarditis
- classic cause of acute endocarditis featuring
- rapid onset of symptoms
- very ill pts
- often no pre-existing valve disease
- Contrast with subacute endocarditis caused by Strep viridans
- slower onset
- less sick patient
- prior valve abnormality
Subacute endocarditis
- subacute endocarditis caused by Strep viridans
- slower onset
- less sick patient
- prior valve abnormality
- As opposed to Staph acute endocarditis
Staph bacteremia
common cause is central lines
most important prevention technique is the sterile technique
- wash hands
- gloves
- sterile insertion practices
Staph osteomyelitis
- Staph is a common cause of osteomyelitis
- in children often occurs in long bones
- femur
- tibia
- fibula
- in adults
- usually spine
- hematogenous spread
- spread from skin soft tissues
- Trauma (surgery)
- symptoms
- localized pain +/- fever
- Dx: imaging (CXR, CT or MRI)
Classic causes of Osteomyelitis
- Child
- staph aureus (hematogeonous spread)
- Sickle Cell patient (functionally asplenic)
- Salmonella (hematogenous spread)
- TB pts
- Pott’s Disease (vertebrae/spine)
- Diabetic
- Polymicrobial from foot ulcer
- bedbound pts
- polymicrobial from pressure sores
Staph cellulitis
infection of deep dermis and subcutaneous fat
Most often cause by beta-hemolytic strep but S aureus can also cause it
Use antibiotics that cover staph and strep
