Staph: bacteremia, sepsis, and MRSA Flashcards
What type of colonies does Staph form on blood agar
Coag + = Golden B-hemolytic
Coag - = Small, White non-hemolytic
Coagulase negative infections as important causes of infections with…
Prosthetic Devices
Most virulent of staph aureus species?
Staph aureus
Is S. Aureus an exogenous bacteria?
Normal human flora
25-50% of healthy persons
Heavier S. Aureus colonization happens among…
Insulin-dependent Diabetics
HIV patients
Hemodialysis patients
Skin Damaged Patients
Sites of human colonization
Anterior nares Skin Vagina Axilla Perineum Oropharynx
Diseases assocaited with increased S. Aureus risk?
Diabetes
PMN defects (chronic gran. disease, neutropenic, Job’s or Chediak-Higashi syndrome)
Skin Abnormalities
Prosthetics
How does MRSA tend to present?
Mostly infections of skin, tissue
approx 5-10% invasive
Pathogenesis of S. Aureus?
Pyogenic organism causes abscess at primary/distant sites
Inflammatory Response -> Initial PMNS -> Mac and Fibro infiltration
Contained or spreads to adjacent tissues/bloodstream
Whay give Bactrim?
A kind of shitty option for MRSA
Hyperkalemia, Nausea
Not a good Strep drug
Why give Kephlex?
Strep and Methycillin sensitive
Not MRSA
Toxin mediated S. Aureus disease
Cytotoxins at site
Pyogenic toxin superantigens (food bourne, TSS)
Exfoliative toxin (Staphylococcal scalded skin syndrome)
TSS treatment
Clindamycin
Stops bacterial protein synthesis to stop toxin production
Vaccination for S. Aureus?
Anti-S. Aureus antibodies have only been shown to be protective in vitro, but never in clinical trials
No. No Vaccine for you. Go away now.
Skin and soft tissue manifestations of S. Aureus
Impetigo (Epidemal Infection)
Folliculitis (Infections of superficial dermis)
Fununcles, Carbuncles, and Abscesses
Hidradenitis suppurativa (follicular inflam of intertriginous areas)
Cellulitis, Erysipelas, and fascitis (Infection of SubQ)
Pyomytosis (Infection of skeletal muscle)
CV manifestations of S. Aureus
Infective Endocarditis
Cardiac Device Infection
Intravascular catheter infection
Septic thrombophlebitis
Bone, Joint Infection
Osteomyelitis
Prosthetic Joint Infection
Septic Arthritis/Bursitis
S. Aureus manifestations (not including Skin, CV, or Bones)
Bacteremia, Sepsis/TSS Splenic Abscess Pulm Infection Meningitis (usually head trauma, neuratrauma) Bacteriuria (indwelling catheter)
Is strep viridins in the blood bad
Real bad…endocarditis and such
Also…don’t ignore yeast in the blood
How many blood cultures to you order
Two or more
S. Aureus sepsis is usually preceded by..
Bacteremia
Leading cause of community and healthcare acquired bacteremia
S. Aureus
What is bacteremia
presence of viable bacteria in the blood
Three categories of S. Aureus
Healthcare-associated hospital onset
Community Acquired
Healthcare acquired community onset (long term care)
Risk factors for S. Aureus sepsis
IV Catheters
MRSA colonization
Implanted prosthetic devices
Injection drug use
Typical S. Aureus infection history
Recent skin, soft tissue infection Presence of indwelling prosthetic devices Injection Drug Use Recent Hospital Exposure IV catheter
Symtoms of metastatic S. Aureus bacteremia
Bone/Joint Pain Protracted fever/Sweats Abdominal Pain (Splenic Infarction) CVA tenderness (renal infarction, psoas abscess) Headache (Septic Emboli)
Physical exam findings in S. Aureus bacteremia?
Careful cardiac exam for new murmurs, evidence of HF
Stigmata of endocarditis
Neurological exam
Diagnostic Evaluation of S. Aureus bacteremia
Blood Cultures
Echocardiography
Other imaging may be necessary based on symptoms