Staph, Sepsis, MRSA Flashcards
Colony appearance by Coag+/- staph
S. aureus= gold beta hemolytic
Coag (-) = small white nonhemolytic colonies
___% of healthy people may be _____or _____ colonized with S. aureus
25%
persistently or transiently
Colonization rate of S. aureus is higher among…(4)
IDDM
HIV
Hemodialysis
Skin Damage
Diseases with increased risk for S. aureus infection (4)
- DM
- PMN defect/deficiency (neutropenia,CGD, Jobs, Chediak-Higashi)
- Skin abnormalities
- Prosthetic devices
Most MRSA infect
Skin and soft tissue
*5-10% have been invasive
Pyogenic bacterium causes ___ at ___ or ____ sites
abscess
primary or distant
Cells that infultrate after inflammatory response
first PMN
then MQ and FB
Staph vs strep on skin
Strep = rapidly producing cellulitis
Staph = Purulent foci
___ is alright for MSSA, but not MRSA
Bactrim
Staph produces what three toxins
- Cytotoxins
- Pyrogenic Superantigen toxins
- Foodborne (Enterotoxin)
- Staphylococcal TSSS (TSST1)
- Exfoliative toxin
TSST1 produced at …
site of colonization
antistaph antibodies efficacy?
Not shown to be protective in vivo. No vaccine available.
Exfoliative toxin mediates…
SSSS
For Staph toxins, you want to use ABs that do what?
halt protein synthesis
(e.g. Clindamycin)
Clinical manifestations - skin and soft tissue infection (6)
- Impetigo
- Folliculitis
- Furuncle/carbuncle, abscess
- Hidradentitis suppurativa (intertriginous)
- Cellulitis/erysipelas/Fasciitis
- Pyomyositis
General clinical manifestations of staph (9)
- Skin and soft tissue infections
- Bacteremia
- CV infection
- Sepsis and TSS
- Splenic abscess
- Bone and Joint infection
- Pulmonary infection
- Meningitis
- Bacteruria
S. aureus meningitis most commonly occurs in the setting of…
in setting of head trauma or neurosurgery
Blood cultures: never order…
just one. (always two)
Three catergories of staph infections
- Healthcare-associated (nosocomial)
- Community acquired
- Healthcare associated community onset (long-term care facilities)
Risk factors for bacteremia (4)
IV catheters
MRSA colonization
Implants/prosthetic devices
IV drug use
Staph Sx - bone and joint pain
Vertebral osteomyelitis
Discitis
Epidural abscess
Staph bacteremia Sx - Protracted fever/sweats
endocarditis
LUQ pain in staph bacteremia
Splenic infarction, abscess
Staph bacteremia Sx - CVA tenderness
Renal infarction
psoas abscess
Staph bacteremia Sx - Headache
Septic embolus
Staph Aureus physical exam should look for what 3 things?
Cardiac exam for new murmurs or evidence of HF
Stigmata of endocarditis
neurological exam
What are the stigmata of endocarditis
Roth spots = retinal hemorrhages with pale centers
Osler’s nodes = Painful immunologic lesions on hands/feet
Janeway’s lesions = Non-tender, non immunologic lesions (hands/feet)
(also petechiae, splenomegaly, murmur, clubbing, fever)
Treatment of Staph aureus bacteremia may include ____ depending on sensitivity results
Empiric antibiotics
DOC for empiric treatment of SA bacteremia
Vm
(toxicity is concern)
Consider _____ or ______ for MSSA
Nafcillin/oxacillin
or cephazolin
Followup blood cultures ___ after initiating therapy to demonstrate clearance
48-72 hours
(should be daily)
Duration of therapy for uncomplicated infection (abscence of cardiac abnormalities)
14 days of IV therapy
Penicillinase resistant Pens
Nafcillin
Oxacillin
_______ related infections present special management problems
Central IV catheters
Enterococcus is resistant stuff. What do you use to treat?
Vm, Pen, Linezolid
(ceph, macrolides, fluoroquinolone = NO)
In sepsis, signs occur…
in tissues remote from the site of infection
SIRS =
clinical syndrome complicating a noninfectious insult
(–> pancreatitis, pulmonary contusion)
Sepsis Step
2 SIRS
*and*
Confirmed or suspected infection
Step for Severe sepsis
- Sepsis + Signs of end organ damage
- Hypotension
- Lactate >4mmol
Step for Septic Shock
- Severe sepsis + signs of end organ damage
*and*
- PERSISTENT hypotension
- Lactate >4mmol
Septic Shock =
Sepsis-induced HoTN persisting despite fluid resuscitation
Septic shock is a _____ shock
Vasodilatory
Sepsis risk factors
- ICU with nosocomial
- Bacteremia
- >65
- IC patients
- IDDM
- Cancer
- CA-PNA
- Genetic stuff
Incidence of sepsis is greatest among…
African american males >65 in winter
Sepsis is more frequently caused by gram __ organisms
positive
Four steps in clincial eval of Septic patient
- Determine source
- Assess respiratory status
- assess perfusion
- assess end organ effects (lactate,renal/hepatic fxn)
Ways to evaluate LRT-associated sepsis
- Sputum
- Rapid influenza test
- Urinary antigen testing (pneumococcus, legionella)
- Bronchiolar lavage
General early management of sepsis (3)
Airway control
Venous access
Maintain perfusion
Control of septic focus by ___ or _______
early ABs
Possible debridement/surgery
Vasoactive agents in septic shock
Which are dilatory?
Dobutamine**
DA/EPI/NE
Phenylephrine
Amrinone**
Phenylephrine has no effect on ___ or _____
heart rate or contractility
Sepsis mortality estimate
10-50%
Methicillin resistance is mediated by
PBP-2a
encoded by the mecA gene
mecA gene is located on a ______
mobile genetic element
Staph chromosomal cassette= SCCmec
HA-MRSA occurs __ after hospitalization or within ____ of exposure to healthcare
48 hrs
12months
HA-MRSA is the leading cause of
Surgical site infections
HA MRSA electrophoresis pattern
USA100
USA200
CA-MRSA is associated with _____ infections
skin and soft tissue infections in healthy young persons
CA-MRSA electrophoresis pattern
USA300 or USA400
ABs that may have played a role in development of MRSA
Ceph
FQ
In both examples of AB resistance spread (human and animal),the resistent bacteria develop within ____
the GIT
The association of antimicrobial drugs and MRSA was stronger for persons who had recieved…
more Rx’s ofany class of antimicrobials
Community acquired or health care associated greater?
HCA
MRSA increased drastically (2k–368k) from…
1993 to 2005
Key interventions for prevention of MRSA (4)
- Hand hygeine
- Decontamination
- Contact precautions
- Active surveillance cultures (ASCs)
Next threat on the horizon
VRSA
Major Vm issue
ototoxicity
