PHM203 (ID) - Allergies, PK, SSTIs, C.
Diff, Influenza, Pneumonia, TB,
Antifungals, MDROs questions and
answers 2025
Tips for the midterm:
Focus on treatments. Learn spectrum cause it's easy to understand
treatment once you learn spectrum. Questions are case-based, similar
to derm. Antibiotic spectrum questions were only based on the ones
emphasized in class.
How can one screen for MSSA? --- correct answers ---Treat organism
with oxacillin/cloxacillin. If the organism is sensitive to
oxacillin/cloxacillin, it will predict cefazolin and cefuroxime
susceptibility.
I say oxacillin/cloxacillin because the notes contradict each other.
What is the mechanism of action of MRSA resistance? --- correct
answers ---There is a mecA gene that causes mutation in PBP. This
prevents beta-lactams from binding.
,The gene spreads horizontally (through mobile gene element).
Which exotoxin is associated with community-acquired MRSA? ---
correct answers ---Panton-Valentine Leukocidin (PVL) exotoxin.
It causes breakdown of skin and causes abscess and tissue necrosis.
Since CA-MRSA is associated with PVL, CA-MRSA is more virulent.
Which is more susceptible to first-line drugs, CA-MRSA or HA-MRSA? -
-- correct answers ---CA-MRSA.
What is difference between primary and secondary SSTIs? --- correct
answers ---Primary:
- previously healthy skin
- single pathogen
Secondary:
- damaged skin
- polymicrobial
What are the characteristics of complicated SSTIs? --- correct answers
---SSTI presenting with:
,- infected ulcer
- burns
- cellulitis with associated abscesses
Briefly describe characteristics of impetigo infection. --- correct
answers ---- Highly contagious superficial skin infection
- 7-10 day incubation period
- Risk factors include young children, hot and humid weather, minor
skin abrasions, close contact with infected individuals
- May resolve spontaneously in 2-3 weeks
Non-bullous form (70%):
- itchy rash of fluid-filled vesicles which may form crusts
- hands and face
- minimal systemic symptoms
Bullous form (30%):
- More frequents affects neonates
- Large bullous vesicles that rupture and form thin, brown crusts
- Affects trunk more often
, What are typical pathogens of impetigo? --- correct answers ---Group
A Strep (GAS)
Staph aureus (including MSSA + MRSA)
What are complications of impetigo? --- correct answers ---- cellulitis
may develop if left untreated
- lymphangitis
- acute rheumatic fever
- rheumatic heart disease
What is first-line therapy for mild cases of impetigo? --- correct
answers ---*Topical* mupirocin or topical fusidic acid
Apply BID for 5-7 days
Less resistance is associated with mupirocin.
Both medications cover gram positive, and have moderate efficacy
with gram negative.
Fusidic acid also has anaerobe coverage.
Systemic therapy is indicated for febrile, or ill-appearing child.
Diff, Influenza, Pneumonia, TB,
Antifungals, MDROs questions and
answers 2025
Tips for the midterm:
Focus on treatments. Learn spectrum cause it's easy to understand
treatment once you learn spectrum. Questions are case-based, similar
to derm. Antibiotic spectrum questions were only based on the ones
emphasized in class.
How can one screen for MSSA? --- correct answers ---Treat organism
with oxacillin/cloxacillin. If the organism is sensitive to
oxacillin/cloxacillin, it will predict cefazolin and cefuroxime
susceptibility.
I say oxacillin/cloxacillin because the notes contradict each other.
What is the mechanism of action of MRSA resistance? --- correct
answers ---There is a mecA gene that causes mutation in PBP. This
prevents beta-lactams from binding.
,The gene spreads horizontally (through mobile gene element).
Which exotoxin is associated with community-acquired MRSA? ---
correct answers ---Panton-Valentine Leukocidin (PVL) exotoxin.
It causes breakdown of skin and causes abscess and tissue necrosis.
Since CA-MRSA is associated with PVL, CA-MRSA is more virulent.
Which is more susceptible to first-line drugs, CA-MRSA or HA-MRSA? -
-- correct answers ---CA-MRSA.
What is difference between primary and secondary SSTIs? --- correct
answers ---Primary:
- previously healthy skin
- single pathogen
Secondary:
- damaged skin
- polymicrobial
What are the characteristics of complicated SSTIs? --- correct answers
---SSTI presenting with:
,- infected ulcer
- burns
- cellulitis with associated abscesses
Briefly describe characteristics of impetigo infection. --- correct
answers ---- Highly contagious superficial skin infection
- 7-10 day incubation period
- Risk factors include young children, hot and humid weather, minor
skin abrasions, close contact with infected individuals
- May resolve spontaneously in 2-3 weeks
Non-bullous form (70%):
- itchy rash of fluid-filled vesicles which may form crusts
- hands and face
- minimal systemic symptoms
Bullous form (30%):
- More frequents affects neonates
- Large bullous vesicles that rupture and form thin, brown crusts
- Affects trunk more often
, What are typical pathogens of impetigo? --- correct answers ---Group
A Strep (GAS)
Staph aureus (including MSSA + MRSA)
What are complications of impetigo? --- correct answers ---- cellulitis
may develop if left untreated
- lymphangitis
- acute rheumatic fever
- rheumatic heart disease
What is first-line therapy for mild cases of impetigo? --- correct
answers ---*Topical* mupirocin or topical fusidic acid
Apply BID for 5-7 days
Less resistance is associated with mupirocin.
Both medications cover gram positive, and have moderate efficacy
with gram negative.
Fusidic acid also has anaerobe coverage.
Systemic therapy is indicated for febrile, or ill-appearing child.
