13 - Staph/Strep Clinical Correlations Flashcards
What is the clinical thought process that you should use when a patient comes in with a potential infection?
- Is this patient infected? - redness, pain, heat, loss of function
- What is the likely infecting organism?
- Where did it come from (and is it removable)?
- Where has it gone? - does it need debridement?
Pertaining to staphylococci, what are the three types that are associated with human infection and what is the order of severeity?
S. epidermidis-like group: usually non-virulent and rarely cause infections. Usually from hospital.
S. lugdunensis: bridges gap between virulent and non-virulent.
S. aureus: bad infections
What are the B-hemolytic streptococci? Which are sensitive to penicillin?
S. pyogenes (group A): PCN sensitive
S. agalactiae (group B): mostly PCN sensitive but some aren’t
S. dysglactiae (C and G) can be sensitive or non sensitive to penicillin
What are the non-B-hemolytic Streptococci? Are these penicillin sensitive?
S. pneumoniae
S. gallolyticus (bovis)
Viridans Streptocicci
Cann’t assume penicillin sensitivity for any of these.
What are typical infections caused by staphylococcus aureus?
Purulent cellulitis Nosocomial infections Surgical site infections Pneumonia Catheter-associated Endocarditis
What are infections caused by coagulase negative strep?
Nosocomial infections: catheter-associated, surgical site infections, prosthetic infection.
What bacteria causes acute lymphangitis, a red rash whose path follows the path of lymph?
Group A strep
What can result from group A strep infecting the skin (dermis and/or epidermis)?
Erysipetis
Impetigo
Folliculitis
Ecthyma
What can result from group A strep infecting subQ tissue? What are the symptoms?
Necrotizing fasciitis, which causes dramatic pain, mild swelling, and erythema.
Cannot be cured and must be taken to the OR for debridement.
What is the appearance of impetigo caused by group A strep?
Erythematous rash with well-defined border.
Gold crust.
How would you distinguish a staph aureus skin infection from a group A strep infection?
If there is purulence, it’s almost always categorized as staph aureus.
Non-purulent it’s group A strep.
What is the usual colonization site of staphylococcus aureus?
Skin
What are the common sites of infection associated with the streptococcus genus?
Skin
Large intestine
Oropharynx
Small Intestine
A 25 yo came in with a R handed lesion that’s swollen and painful. He has chills with 38.6, HR of 145, and a BP of 73/25. His WBC count is high and he has impaired kidney function. He also has swelling extended proximally to the elbow, and limited range of motion in the fingers. What type of infection does he have? What is the treatment?
He is in septic shock. He has necrotizing fasciitis that needs immediate surgical debridement.
A 59 yo patient comes in with a fever, confusion, thrombocytopenia, rash, and renal failure. He has had fatigue, vomiting, and diaphoresis for 3 days. He also has a large vegetation on his aortic valve. What is causing this? What does he have?
He has endocarditis caused by staph aureus.
Damaged _____ _____ leads to damaged heart valve. What can cause this damage?
Endothelial layers.
PMNs.
Hospital endocarditis is usually caused by what organism?
Streptococcus.
Both staph and strep can cause endocarditis but it’s more commonly caused by strep.
What are super antigens and what organism produces them?
Made by all staph aureus isolates.
Strep pyogenes makes up to 11 kinds.
Cause activation of up to 50% of T-cells causing a cytokine storm that results in toxic shock syndrome.
What drugs can be used to treat toxic shock syndrome? How do they work?
Clindamycin and linezolid.
Bind ribosome to impair protein synthesis.
A patient comes in with acute polyarthritis, what is the organism that can cause this? What other symptoms are associated with it?
This is acute rheumatic fever which is secondary to pharyngeal infection caused by group A streptococcus.
2/3 of pts do not recall having a sore throat, and 75% have a negative strep throat culture.
A 36 yo man presents with 1 month fever and pain in his shoulders and knee after having a sore throat. He subsequently develops an evanscent non-pruritic macular rash. What is the diagnosis?
Erythema marginatum caused by rheumatic fever (form group A strep)
What are the major criteria for Rheumatic fever?
Carditis Polyarthritis Chorea (jerky movements) Erythema marginatum SubQ nodules
What antibiotic can decrease the production of toxins?
Clindamycin
What bacterium is suspected to be the most common cause of non-purulent cellulitis?
Streptococcus pyogenes
