Antibiotics Flashcards
What is the cellular structure of gram positive bacteria & how do the cells stain?
Cell walls have thick layers of peptidoglycan in gram positive bacteria
-Stain purple
What is the cellular structure of gram negative bacteria & how do the cells stain?
Thin layer of peptidoglycan in gram negative bacteria
Stain pink
What are the groups of bacteria that are gram positive organisms?
- Staphylococcus sp.
- Streptococcus sp.
- Enteroccus sp.
What are the two types of Staphylococcus sp. organisms? Name the type of organisms & subtypes of each
Gram positive
• Coagulase positive: S. aureus
- methicillin|oxacillin sensitive S. aureus = MSSA
- methicillin|oxacillin sensitive S. aureus = MRSA
• coagulase negative Staphylococcus
- methicillin sensitive S. Epidermis= MMSE
- methicillin resistant S. Epidermis= MRSE
What are the types of Streptoccus sp. organisms? Name the types of each organism
Gram positive
Alpha hemolytic: Steptoccus pneumoniae
Beta hemolytic: group A Streptococcus sp = S.pyogenes
What type of organism is Enterococcus sp.? Name each type
Gram positive
•Enterococcus faecalis/enterococcus facium
• Vancomycin Resistant Enterococcus = VRE
What are the types of gram negative organisms?
- Enterobacteriaciae: E.coli, klebsiella sp, Proteus sp.
- Respiratory: H. influenza, M. catarrhalis
- Pseudomona aeruginosa
What group of bacteria do bacteroides sp. belong to?
Anaerobes
What are the atypical types of bacteria?
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Legionella pneumopniae
What type of organism is Escherichia coli (E. coli) & where are they found in the body?
Enterobacteriaciae - gram negative
• GI flora of humans & animals
What type of organism is Klebsiella sp. and where is it found in the body?
Enterobacteriaciae - gram negative
•nasopharynx
• GI flora
What type of organism is Proteus sp. and where are they found?
Enterobacteriaciae - gram negative
• soil
• GI flora
• water and sewage
What is the drug of choice for streptococcus organisms? What types of bacteria are they?
Natural Penicillin
• Gram positive
- Pneumoniae (resistance is increasing)
- Enteroccus
What Gram negative organisms does natural Penicillin cover?
• Neisseria
- gonorrhoeae ( need to use with another drug to be effective)
-Meningitidis
• Treponema palladium (syphillis)
What are the adverse reactions of natural Penicillin?
- Hypersensitivity
- GI symptoms: N/V/D, abd p
- interstitial nephritis
- Neurotoxicity
- Hematologic toxicity
What is considered a true allergy to penicillin?
Anaphylaxis
* rash can be concerning
What is the most common type of aminopenicillin? What is the spectrum of activity for this drug?
Amoxicillin PO
• Gram positive:
-Streptococci
-Enterococcus (drug of choice)
• Gram negative:*
- Proteus sp
- E.coli
- H. Influenza
- all beta lactamase negative
What are the adverse reactions of aminopenicillins?
Similar to natural penicillin but 10% of patients will develop non puritic, non-urticarial skin rash • Hypersensitivity • GI symptoms: N/V/D, abd p • interstitial nephritis • Neurotoxicity • Hematologic toxicity
Can a patient with a true PCN allergy be prescribed Amoxicillin and why?
No, they will have anaphylaxis or develop a rash
What 3 drugs are categorized as penicillinase-resistant penicillins?
PO: Dicloxacillin
IV: Nafcillin, Oxacillin
What is the spectrum of activity of penicillinase-resistant Penicillins?
Gram positive organisms:
Staphylococcus sp. -MSSA/MSSE -> Drug of choice
Streptococcus sp
No gram negative or anaerobes
What are the adverse reactions of penicillinase-resistant penicillins?
Allergic reactions
Interstitial nephritis
Increased LFTs with oxacillin
What is a drug interaction that penicillinase-resistant Penicillins cannot be prescribed with and why?
Warfarin: will cause patient to bleed out
What two drugs are classified as anti-pseudomonal penicillins?
Piperacillin IV * more potent
Ticarcillin IV
- Typically grouped w/ another drug
What is the spectrum of activity anti-pseudomonal penicillins on gram positive organisms?
Streptococcal sp
Enterococcus
What is the spectrum of activity anti-pseudomonal penicillins on gram negative organisms?
• Beta-lactamase negative
- E. Coli
- K lebsiella sp
- Proteus sp.
- H. influenza
- M. Catarrhalis
Pseudomonas
What are the adverse reactions of anti-pseudomonal PCN?
- allergic reactions
- Electrolyte abnormalities
- interstitial nephritis
- seizure, delirium, psychosis
- neutropenia, thrombocytosis
What are the most commonly used beta-lactamase inhibitors?
PO: Amoxicillin-Clavulanic Acid (Augmentin)
IV: Ampicillin-Sulbactam (Unasyn)
IV: Piperacillin-tazobactam (Zosyn) - anti pseudonomal
Why are -cillin drugs combined with other drugs?
- They have little antimicrobial on their own
- Combination w/ beta-lactamase inhibitors protects them from deactivation of gram negative bacteria that produce beta lactamase (& gram+ Staphylococcus sp)
What drugs are classified as monobactams?
IV: Aztreonam (Azactam)
Inhalation: Aztreonam (Cayston)
What is the spectrum of activity for monobactams?
Gram negative organisms only:* •E.coli • Klebsiella sp • proteus sp •H. influenza • M. catarrhalis • Pseudomonas
- No gram positive & no anaerobes
What antibiotic can safely be prescribed to patients with a penicillin allergy?
Aztreonam
- only 1 beta-lactam ring that is not fused to another ring
- Little cross-sensitivity
What are the adverse reactions of monobactams?
Abnormal liver function
Phlebitis
Skin rash
Must reduce dose if pt has poor renal function
What drugs are classified as carbapenems?
IV Etrapenem (Invanz) -> imipenem - cilastatin* Meropenem (Merrem) -> Meropenem-Vaborbactam (Vabomere) -> Doripenem
- imipenem is always coupled with cilastatian to protect it from metabolism by renal dehydropeptidase I
What is the only carbapenem that covers gram + Enterococcus faecalis
Imipenem
All of the following carbapenems cover pseudomonas except: Ertapenem (Invanz) Imipenem Meropenem Doripenem
Ertapenem
What group of organisms do all carbapenems cover?
Anaerobes: Bacteroides sp.
What are the adverse reactions of carbapenems?
More common: HA, allergic rash/fever,N/V, hypotension, dizziness Less common: Seizures Renal failure Increase in LFTs
What drug interacts with carbapenems? Which carbapenem is safe to give Rx to patient that is on the drug that it interacts with?
Valproic acid / Depakote
- Rx of meropenum to any elderly patient with hx of seizures
Increases LFTs
How would you give a carbapenem to a patient with a penicillin allergy?
- First dose-low in a controlled setting
- Slowly titrate up and monitor patient
Or administer full dose in a supervised setting (inpatient or ER)
What drug protects against Carbapenemases?
Meropenum + Vaborbactam = Vabomere
Only administered IV
- must extend dose b/t time interval for patients with renal insufficiency
What groups of antibiotics are cell wall inhibitors?
Penicillins, cephalosporins, carbapenems, monobactams
What is the mechanism of action of cephalosporins?
Bactericidal
Break down Penicillin binding proteins in cell wall
- structurally & functionally similar to Penicillins
- affected by penicillinases & beta lactamases
What drugs make up the first generation of cephalosporins?
PO: cephalexin (Keflex)
IV: cefazolin (ancef /kefzol )
What drugs make up the second generation of cephalosporins?
Cefuroxime
-Cefuroxime axetil (Ceftin) IV/PO
Cefotetan IV
Cefoxitin IV
What drugs make up the third generation of cephalosporins?
IV: Ceftriaxone (Rocephin) Cefpodoxime proxetil (Vantin) Cefotaxime (Claforan) Ceftazidime (Fortaz)
PO:
Cefidinir (Omnicef)
Cefixime (suprax) PO
What drug is a fourth generation of cephalosporin?
Cefepime (Maxipime) IV
What drug is a fifth generation of cephalosporin?
Ceftaroline fosamil (Teflaro) IV
What is the mechanism of action of all cephalosporins as a whole?
Bactericidal
Time dependent killing: duration of time above MEC is what matters
What is the spectrum of activity of first generation cephalosporins? What type of infections are they commonly used for?
*Gram positive: Staphylococcus (most active)
Streptococcus sp.
Gram negative:
E. coli
Klebsiella sp.
Proteus sp.
- good for skin infections
What is the spectrum of activity of second generation cephalosporins on gram negative organisms? What type of infections are they commonly used for?
Gram negative
E. coli Klebsiella sp. Proteus sp. H. influenza Moraxella catarrhalis
- good for respiratory pathogens
What is the spectrum of activity of second generation cephalosporins on gram positive organisms and anaerobes?
Gram positive:
Staphylococcus (less active) & Streptococcus sp.
Anaerobes: Bacteroides
What is the spectrum of activity of third generation cephalosporins on gram positive organisms?
Gram positive:
Staphylococcus (less active) & Streptococcus sp.
What is the spectrum of activity of third generation cephalosporins on gram negative organisms?
Gram negative:
+ Pseudomonas
N. Gonorrhea
Covers same 1st & 2nd gen organisms: E. coli Klebsiella sp. Proteus sp. H. influenza Moraxella catarrhalis
How do 3rd generation cephalosporins differ from all others?
They are the only antibiotics that can cross the blood brain barrier
Good for meningitis: easier access in inflammation
What is the spectrum of activity of 4th generation cephalosporins on gram negative organisms?
+ pseudomonas
What is the spectrum of activity of 4th generation cephalosporins on gram positive organisms?
Streptococcus & Staphylococcus
What is the spectrum of activity for 5th generation cephalosporins?
MRSA: 5th gen cephalosporins are the only generation that can cover MRSA
Streptococcus
Similar gram negative activity as ceftriaxone
