How does IDSA categorize skin and soft tissue infections?
Purulent vs non-purulent
What is the usual organism found in purulent skin infections?
What is the usual organism found in non-purulent skin infections?
Group A Streptococci
What are characteristics of non-purulent skin infection?
- Necrotizing infection
What are the characteristics of purulent skin infection?
What is the initial treatment for a severe skin infections?
Empirically treat with vancomycin and piperacillin/tazobactam, if suspected Staph. aureus, must cover MRSA
What route of administration would you use to treat moderate non-purulent skin infection?
What is the drug used to treat moderate non-purulent skin infection?
What route of administration would you use to treat mild non-purulent skin infection
What are the drugs used to treat mild non-purulent skin infections?
Oral penicillin or dicloxacillin
What is the drug used to treat moderate purulent skin infection?
Oral TMP or doxy
What is the drug used to treat severe purulent skin infection?
What is defined therapy?
It is after you do a C&S and have a target organism, can then deescalate abx treatment
What is the mechanism of action of clindamycin?
Inhibits protein synthesis by binding to 50S ribosomal subunits of microbe
Which bacteria do clindamycin target?
- Gr+ aerobes such as Group A and B Streps, S.penumoniae and S.aureus including MSSA, MRSA
- Gr- anaerobes such as Bacteroides
True/False: Clindamycin has antimicrobial activity on Gr- aerobes like E.coli
False; Clindamycin targets Gr+ aerobes and Gr- anaerobes
What are some clinical indications for clindamycin?
- Oral and IV forms to treat systemic infections; Necrotizing fasciitis
- Topically to treat acne
- Intravaginally to treat for bacterial vaginosis
If a patient is allergic to beta-lactam (penicillin), is it safe to give clindamycin?
How would you treat Necrotizing fasciitis?
Penicillin G and Clindamycin
What are the adverse side effects of Clindamycin?
- Diarrhea (from oral form)
- At risk to develop C.diff colitis
Is Clindamycin a good drug for MSSA / MRSA?
Not anymore, it used to be. Now, it is only about 79% MSSA susceptible and 72% MRSA susceptible to clindamycin
Is Clindamycin a good drug for Bacteroides?
Not anymore, it used to be.
What is the mechanism of action for penicillin?
Inhibit cell wall synthesis
What makes penicillin unique?
It has beta-lactam , which is a four sided ring
How does beta-lactam affect bacterial cell wall?
Inhibit the formation of bacterial cell wall by binding to the transpeptidase enzyme which inhibit the cross-linking of the peptidoglycan
What happens to the bacteria cell that is without cross-linking of peptidoglycan?
Weakened cell wall, leading to intracellular osmotic pressure and rupturing of cell wall
How do bacteria become resistant to penicillin?
They develop a different transpeptidase (penicillin binding protein) where penicillin cannot bind
What is beta lactamase and what is the significant of it?
It is a bacterial enzyme that can breakdown beta-lactam (penicillin), thereby resistant to Penicillin
How do Gr- bacterial resistant to penicillin?
- Outer membrane permeability
- Efflux pump
- B-lactamase production
What are the B-lactamases produced by Gr- bacteria?
- ESBL (extended spectrum B-lactamases)
- KPC (Klebsiella penumoniae carbapenemases)
- MBL (Metallo-B-lactamases: NDM, IMP, VIM)
Bacteria that produce ESBL enzymes can be killed by which abx?
Bacteria that produce carbapenemase (KPC, MBL) are resistant to what?
Most beta-lactam antibiotics
What are the four types of penicillin?
- Natural penicillin
- B-lactamase resistant
- Extended spectrum penicillin
What are natural penicillins and what are they a drug of choice for?
- Penicillin G (IV, IM depot)
- Pencillin V (oral)
- Drug of choice for Group A Strep
What are B-lactamase resistant penicillin and what are they a drug of choice for?
- Drug of choice for MSSA
What are aminopenicillin?
What are extended spectrum penicillin?
- Ticarillin (supplied with clavulanic acid)
- Piperacillin (supplied with tazobactam)
Which penicillin contain B-lactamase inhibitor?
- Ampicillin plus sulbactam (IV)
- Amoxicillin plus clavulanic acid (oral)
- Ticarcillin plus clavulanic acid (IV)
- Piperacillin plus tazobactam (IV)
Which drug can be used to prolong the half-life of penicillin?
Is penicillin safe during pregnancy?
What are some adverse reactions for penicillin?
- Seizures from high levels
- Cause C.diff infection
Which bacteria are penicillin most effective against?
Gr+; GAS, GBS, S.pneumonia, MSSA
True/False: Penicillin is good against MRSA?
What is the mechanism of action of Vancomycin?
Inhibition of bacterial cell wall synthesis
What is the antimicrobial spectrum of activity for vancomycin?
- Gr+ aerobes
- Gr+ anaerobes
What are the bacteria targeted by vancomycin?
- GAS, GBS
- Strep. pneumo
- MSSA, MRSA
- Clostridium difficile
Is vancomycin the drug of choice for MRSA?
How does vancomycin disrupt the cell wall synthesis?
Bind terminal ALA-ALA on peptide chain to prevent peptidoglycan cross-link
How do vancomycin resistance develop?
D-Lactate replaces the last Alanine on NAM peptide so no vancomycin binding
Which route of administration of vancomycin is optimal for MRSA and MSSA?
What does oral/rectal routes of administration of vancomycin useful against?
C.diff because of local effect
What are some possible adverse effects of IV vancomycin?
- “Red neck” syndrome when infusing IV doses too rapidly
- Allergic reaction
- IV administration leads to vein irritation or phlebitis
How to avoid high peak levels of vancomycin?
Slow infusion rate