Beta Lactams Flashcards
What is the function of beta lactam drugs?
Bacterial cell wall
What does a beta lactam ring look like?
What is the target enzyme of beta-lactam drugs?
Transpeptidase enzymes (stops peptidoglycan layer synthesis)
What type of bond is the bond between an antibiotic and the active site?
Covalent bond (very strong, makes beta lactams very effective!)
Renders the enzyme inactive
What are the four common pathogens we use beta-lactam drugs for?
- Strep pyogenes (pharynx and skin) - penicillin G
- Strep pneumo (respiratory infections, meningitis, sepsis) - amoxicillin and ampocillin
- Staph aureus (skin and soft tissue) - methicillin
- Pseudomonas aeruginosa (UTI, sepsis) - piperacillin
Are beta lactam drugs bactericidal or bacteriostatic?
Bactericidal
(kills cell due to osmotic rupture)
What are the four classes of penicillins?
- Natural
- Amino-penicillins
- Anti-staphylococcal
- Extended Spectrum
What must you do for treatment if a patient has a penicillin allergy?
Use a drug from a completely different class
What two drugs belong to the natural penicillin class? What routes are they given?
- Penicillin G (IV, IM) (almost unusable due to bacterial resistance)
- Penicillin V (PO)
What can natural penicillins treat?
- Strep pyogenes (throat and skin) (strep throat & impetigo)
- Oral/dental infections (oral anaerobes)
- Syphilis
What helps penicillins not degrade in stomach acid?
Carbon ring
What two drugs belong to the aminopenicillin class?
- Ampicillin (IV)
- Amoxicillin (PO)
What can amino-penicillins treat?
- Common respiratory tract infections (STREP PNUEMO, Moraxella, Haemoophilus)
- UTIs
- Most E. coli strains
- Same things natural penicillins can treat also
What do you not want to treat with amino-penicillins?
MRSA
What three drugs belong to the class anti-staphylococcal penicillins? And what route are they given?
- Methicillin (IV)
- Nafcillin (IV)
- Dicloxacillin (PO)
What can anti-staphylococcal penicillins treat?
- Staph aureus (skin and soft tissue, internal infections)
- MSSA skin infections (never MRSA)
- Surgical skin prophylaxis (ortho pre-op)
Why are anti-staphylococcal penicillins fairly ineffective?
- Staph aureus did not have great susceptibility to penicillin G….therefore anti staph drugs were developed
- Important historically but due to MRSA, they are ineffective
Why does dicloxacillin have a horrible taste?
It has a chlorine on it
What two drugs are extended spectrum penicillins?
- Piperacillin (IV)
- Ticarcillin (IV)
What can extended spectrum penicillins treat?
-Gram NEGATIVE infections (NOT gram +)
*Only used in hospital for tough to kill Gram - bacteria
*Only penicillin used for gram - (the other three types treat only gram +)
-UTI, intra-abdominal/pelvic infections
What are the 5 classes of cephalosporins?
- 1st generation
- 2nd generation
- 3rd generation
- 4th generation
- 5th generation
What is the MOA of cephalosporins?
Inhibits transpeptidation - blocks cell wall synthesis (same as penicillins)
T/F cephalosporins are beta lactams?
True
What 3 drugs are 1st generation cephalosporins?
- Cefazolin (ancef) - IV only
- Cephalexin (keflex) - PO
- Cefadroxil (duracef) - PO
Do 1st generation cephalosporins treat gram - or gram +?
ONLY Gram +
What do 1st generation cephalosporins best treat?
- MSSA and Strep pyogenes
- Impetigo and cellulitis
Why do orthopedic surgeons like to use 1st generations?
Ortho surgeons give these to patients before surgery to prevent the wound from being contaminated (pre-op orthopedic surgery prophylaxis) - covers staphylococcal skin flora very well
What 2 drugs are 2nd generation cephalosporins?
- Cefotetan (cefotan) - IV
- Cefoxitin (mefoxin) - IV
What are 2nd generation best used for?
Anaerobic prophylaxis
-MSSA and strep pyogenes
Why do general surgeons like to use 2nd generations?
- Covers intra-abdominal/pelvic flora very well
- Given pre-op for surgery involving viscera
Do 2nd generations treat gram + or gram -?
ONLY gram +
What 7 drugs are 3rd generation cephalosporins?
- Cefotaxime (claforan) - IV
- Ceftriaxone (rocephin) - IV
- Ceftazidime (fortaz) - IV
- Cefdinir (omnicef) - PO
- Cefixime (suprax) - PO
- Cefpodoxime (vantin) - PO
- Cefuroxime (zinacef) - PO
What do oral 3rd generations most commonly treat?
-Respiratory tract (strep pneumo +, moraxella -, heamophilus-)
-Urinary tract (E. coli -, enterobacteriacae -)
-Skin (MSSA +, strep pyogenes +)
*highest use for suspected or known penicillin-resistant strep pneumo
Which 3rd generation oral abx is used to treat gonorrhea?
Cefixime
What do IV 3rd generations most commonly treat?
-Respiratory (strep pneumo+, moraxella-, haemophilus-)
-Urinary tract (E. coli -, enterobacteriacae -)
-Skin (MSSA +, strep pyogenes +)
-CSF (strep pneumo+, neisseria meningitis-)
*Used for more sick patients - very good coverage for these infections in hospitalized patients
Which 3rd generation has the longest half life? What does this mean?
Ceftriaxone, means you only need to dose ~1xday
What 3 diseases can be treated with a one time IM ceftriaxone injection?
- Otitis media (save this for kids who cannot take oral)
- Gonorrhea (best overall tx)
- Strep throat (would rather use penicillin G)
What one drug is a 4th generation cephalosporin?
Cefepime (maxipeme) - IV only
When is cefepime commonly used?
Used as an “empiric” treatment when gram negative infection is suspected
Why was cefepime developed?
To enhance effect against pseudomonas (gram -) and gram negatives
(can tx gram + but much better at gram -)
What one drug is a 5th generation cephalosporin?
Ceftaroline (teflaro) - IV
What is the sole purpose of ceftaroline?
ONLY beta lactam that antibiotic that works against MRSA
What are the four carbepenems?
- Imipenem
- Meropenem
- Doripenem
- Ertapenen
What are carbepenems used for?
- SICK inpatients only - sepsis/resistant infections
- Wide spectrum including gram - and anaerobes
- Intra-abdominal, pelvic infectinos
- IV only
