Tips For The Midterm:

PHM203 (ID) - Allergies, PK, SSTIs, C. Diff, Influenza,

Pneumonia, TB, Antifungals, MDROs: Q’s & A’s

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.

True or false: all adverse drug reactions are drug allergies. Right Ans -

False.Predictable drug reactions (e.g. GI upset) is dose dependent and not an allergic reaction.What are the most common types of allergic reactions? Right Ans - Type IV: delayed onset (days to weeks) and symptoms include contact dermatitis and maculopapular rash.

• repeated exposure causes same rxn

Type I: onset within 1 hour and symptoms include urticaria, anaphylaxis

• repeated exposure may cause worse rxn

When is skin testing indicated? Right Ans - For IgE-mediated reactions.Describe the drug-viral interaction with ampicillin. Right Ans - 60-100% of patients with infectious mononucleosis, lymphocytic leukemia, CMV infection, and concurrent allopurinol will develop a nonspecific morbilliform eruption.True or false: risk of reacting to cephalosporins in a patient with a history of a penicillin allergy is less than 1%. Right Ans - True.The R groups cause the cross-reactivity, rather than the beta-lactam group.In a patient with type 1 allergy to penicillin, it is still advised to avoid all cephalosporins if an alternative is available.True or false: fever is a predictor of a more serious drug reaction. Right Ans

• True.

Other red flags include: mucous-membrane involvement (blisters), facial

edema, lymphadenopathy. 1 / 4

True or false: cross-reactions between sulfonamide antibiotics and non-

antibiotic sulfonamides is common. Right Ans - False.The sulfonamide group does not cause cross-reactivity.Instead, the aromatic amine (-NH2) group is thought to cause the allergic reaction.What is a suspension? Right Ans - Coarse dispersion containing finely divided insoluble material uniformly suspended in a continuous (liquid) phase.

Reasons for making:

• oral administration of insoluble drugs
• improve stability
• mask bitter taste of parent drug
• ease oral administration
• some drugs need to be present in the finely divided form to maximize

surface area What are ideal characteristics of a suspension? Right Ans - - Suspended material should not settle rapidly

• Particles that do settle should be readily redispersed
• Suspension should not be too viscous to pour freely from the orifice of the

bottle or to flow through a syringe needle

• Suspended particles must be small and uniformly distributed

True or false: most medicinal materials are hydrophobic. Right Ans - True.Therefore, some wetting material should be used to allow proper formation of suspension. Wetting agents should have an HLB 7-9 (e.g. alcohol, glycerin, surfactants).Which suspension settles faster: deflocculated or flocculated? Right Ans - Flocculated.However, flocculated suspensions can be easily resuspended. In a flocculated suspension, zeta is ~0.Deflocculated suspensions will form a hard cake at the bottom of the container which will be difficult/impossible to redisperse.What are ideal characteristics of a preservative agent in a suspension?Right Ans - - Effective against a wide spectrum of microorganisms 2 / 4

• Neutral charge so they can penetrate membrane of bacteria/microorganism
• Stable
• Nontoxic
• Compatible
• Free of taste and odor

Which organisms are regularly found on the skin? Right Ans - Gram

positive:

• Coagulase-negative Staphylococci
• Micrococcus
• Corynebacterium
• Propionibacterium
• Staphylococcus aureus

Gram negative:

• Acinetobacter

Fungi:

• Malassezia
• Candida

List risk factors for SSTIs. Right Ans - - Too much/not enough skin moisture

• High concentration of colonizing bacteria
• Poor blood supply
• Supplies of bacterial nutrients
• Damage to epidermal layer

What are the most common organisms which cause wound infections? List from most prevalent to least prevalent, and sort by gram positive/negative.

Right Ans - Gram positive:

- MRSA

- MSSA

• GAS
• Staphylococcus lugdunensis/Coagulase negative staph (CONS)
• Enterococcus faecium

Gram negative:

• Pseudomonas aeruginosa 3 / 4

• Escheria coli

How can one screen for MSSA? Right Ans - 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? Right Ans - 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? Right Ans - 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? Right Ans - CA-MRSA.What is difference between primary and secondary SSTIs? Right Ans -

Primary:

• previously healthy skin
• single pathogen

Secondary:

• damaged skin
• polymicrobial

What are the characteristics of complicated SSTIs? Right Ans - SSTI

presenting with:

• infected ulcer
• burns
• cellulitis with associated abscesses

Briefly describe characteristics of impetigo infection. Right Ans - - Highly contagious superficial skin infection

• 7-10 day incubation period
• / 4