Beta Lactams & Cell Wall Synthesis Inhibitors Flashcards
comprehensive
An antimicrobial drug that can eradicate an infection in the absence of host defense mechanisms; kills bacteria.
Bactericidal
An antimicrobial drug that inhibits antimicrobial growth but requires host defense mechanisms to eradicate the infection; does not kill bacteria.
Bacteriostatic
Drugs with structures containing a beta-lactam ring: includes the penicillins, cephalosporins and carbapenems. This ring must be intact for antimicrobial action.
Beta-lactam antibiotics
Bacterial enzymes (penicillinases, cephalosporinases) that hydrolyze the beta-lactam ring of certain penicillins and cephalosporins.
Beta-lactamases
Potent inhibitors of some bacterial beta-lactamases used in combinations to protect hydrolyzable penicillins from inactivation.
Beta-lactam inhibitors
Lowest concentration of antimicrobial drug capable of inhibiting growth of an organism in a defined growth medium.
Minimal inhibitory concentration (MIC)
Bacterial cytoplasmic membrane proteins that act as the initial receptors for penicillins and other beta-lactam antibiotics.
Penicillin-binding proteins (PBPs)
Chains of polysaccharides and polypeptides that are cross-linked to form the bacterial cell wall
Petptidoglycan
More toxic to the invader than to the host; a property of useful antimicrobial drugs.
Selective toxicity
Bacterial enzymes involved in the cross-linking of linear peptidoglycan chains, the final step in cell wall synthesis.
Transpeptidases
What are the examples of bacteriostatic drugs?
- Chloramphenicol
- Erthryomycin
- Clindamycin
- Sulfonamides
- Trimethoprim
- Tetracyclines
What are the examples of bactericidal drugs?
- Aminoglycosides
- Beta-lactams
- Vancomycin
- Quinolones
- Rifampin
- Metronidazole
What are the strategies stated in chemotherapeutic agents?
- Use of adjunctive agents that can protect against antibiotic inactivation
- Use of antibiotic combinations
- Introduction of new (and often expensive) chemical derivatives of established antibiotics
- Efforts to avoid indiscriminate use or misuse of antibiotics
What are the major Beta-lactam antibiotics that inhibit cell wall synthesis?
- Penicillins
- Cephalosporins
Beta-lactams have the unusual _ member ring that is common to all members.
4-member ring
What are the general structure of cephalosporins?
- Acyc side chain
- Beta-lactam ring
- Dihydrothiazine ring
True or False:
Beta-lactam antibiotics are most effective, widely used, and well-tolerated.
True
What are the not as important beta-lactam drugs?
- Vancomycin
- Fosfomycin
- Bacitracin
These are the drugs that inhibits the growth/replication or kill microorganisms, they are classified under chemotherapeutic drugs.
Antimicrobials
What are the following components in bacterial structure?
- Cell membrane
- Cell wall
- Nucleus
- Fimbriae
- Pili
- Ribosomes
- Capsule
What are the components of peptidoglycan bacterial cell wall?
- N-acetylglucosamine (NAG)
- N-acetylmuramic acid (NAM)
Identify if Gr(+) or Gr(-):
Thick peptidoglycan
Gr(+)
Identify if Gr(+) or Gr(-):
Thin peptidoglycan
Gr(-)
True or False:
Peptidoglycans are slightly more hydrophilic compared to the outer membrane.
True
True or False:
Peptidoglycans are composed of repeating units of N-acetylmuramic acid and N-acetylglucosamine.
True
What are the 4 amino acids that composed the tetrapeptide cross-links?
- L-alanine
- D-glutamine
- L-lysine
- D-alanine
True or False:
The groups under miscellaneous in the bacterial cell wall synthesis inhibitors do not have β-lactam rings.
True
True or False:
If bacteria do not have cell walls or cannot regenerate their cell walls, they will be susceptible to our immune system.
True
What are the core structures of four β-lactam antibiotic families?
- Penicillin
- Cephalosporin
- Monobactam
- Carbapenem
What are the β-lactam antibiotics under Penicillins?
- Penicillin G
- Penicillin V
- Methicillin
- Nafcillin
- Oxacillin
- Cloxacillin
- Dicloxacillin
- Amoxicillin
- Carbenicillin
- Ticarcillin
- Pepracillin
- Mezlocillin
- Cefoxitin
- Aziocillin
What are the 1st generation antibiotics under Cephalosporins?
- Cefazolin
- Cefadroxil
- Cephalexin
- Cephalothin
- Cephapirin
- Cephradine
“FA/PHA”
What are the 2nd generation antibiotics under Cephalosporins?
- Cefaclor
- Cefamandole
- Cefonicid
- Cefuroxime
- Cefprozil
- Loracarbef
- Ceforanide
What are the 3rd generation antibiotics under Cephalosporins?
- Cefoperazone
- Cefotaxime
- Ceftazidime
- Ceftizoxime
- Ceftriaxone
- Cefixime
- Cefpodoxime proxetil
- Cefdinir
- Cefditoren pivoxil
- Ceftibuten
- Moxalactam
What is the 4th generation antibiotic under Cephalosporins?
Cefepime
What is the 5th generation antibiotic under Cephalosporins?
Ceftobiprole
He suggest that a Penicillium mold must secrete an antibacterial substance.
Alexander Flemming
What is the derivative of Penicillin?
6-aminopenicillanic acid
Penicillin is excreted via:
Urine
What is the basic structure of Penicillins?
- Thiazolidine ring
- β-lactam ring (carries secondary amino group)
Penicillin pharmacokinetics:
Vary in their __ bioavailability.
oral
Penicillin pharmacokinetics:
UTIs are usually caused by Gr(_) bacteria.
Gr(-)
Penicillin pharmacokinetics:
Penicillin are _ and not _ extensively.
polar; matabolized
Penicillin pharmacokinetics:
Penicillins are excreted unchanged in urine through what type of filteration?
- Glomerular filtration
- Tubular filtration
Penicillin pharmacokinetics:
Tubular execretion is inhibited by:
Probenecid
Penicillin pharmacokinetics:
What are the two drugs that cross the BBB when meninges are inflamed, given IM, has long half-lives, and released slowly?
- Procaine
- Benzathine penicillin G
Penicillin pharmacokinetics:
Penicillin must be given on an empty stomach due to its gastric acidity, except:
Amoxicillin
Penicillin pharmacokinetics:
Nafcillin is primarily cleared by _ excretion.
billiary
What are the mechanism of action in Penicillin?
- Bactericidal drugs
- Inhibit cell wall synthesis
- Inhibit bacterial growth by interfering with the transpeptidation reaction
What are the mechanism of resistance against Penicillin?
- Hydrolysis of β-lactam ring by bacterial β-lactamases (inactivation)
- Modification of PBP
- Changes in membrane permeability
- Antibiotic efflux
Penicillin resistance:
What is the most common mechanism of resistance in Penicillin?
β-lactamase production
Penicillin resistance:
Resistance due to impaired penetration of antibiotics occurs only in Gr(_) species.
Gr(-) species
Penicillin resistance:
Gr(-) organisms may produce an ___ ___, which consists of cytoplasmic and periplasmic protein components that efficiently transport some β-lactam antibiotics from the periplasm back across the cell wall outer membrane.
efflux pump
Clinical uses of Penicillin:
Oral penicillins should be given _ hours before or after a meal; they should not be given with food to minimize binding to food proteins and acid inactivation.
1-2 hours
Clinical uses of Penicillin:
Probenecid impairs renal tubular secretion of weak acids such as β-lactam compounds and should be be administered _ g every _ hours orally.
0.5 g; 6 hours orally
What are the Narrow Spectrum Penicillinase Susceptible Agents?
- Penicillin G
- Penicillin V
Identify if Penicillin G or V:
- Limited spectrum
- Susceptible to β-lactamases
Penicillin G
Identify if Penicillin G or V:
- Oral counterpart of Penicillin G
- Use for prophylaxis against bacterial endocarditis among patients with valvular heart disease
Penicillin V
Penicillin G is used for:
- Streptotocci (sore throats)
- Meningococci (meningitis)
- Gram-positive bacilli
- Spirochetes (Treponema pallidum)
What is the first line of drug for syphilis and is administered intramuscularly?
Benzathine Penicillin G
What type of Penicillin G is used for treating β-hemolytic streptococcal pharyngitis and is given once every 3-4 weeks to prevent reinfection?
Benzathine penicillin
What type of Penicillin G is commonly used for treating pneumococcal pneumonia and gonorrhea; however it is now rarely used?
Procaine penicillin G
Penicillin V is indicated only in minor infections due to its:
- Poor bioavailability
- Need for dosing 4 times a day
- Narrow antibacterial spectrum
What are the Very-narrow-spectrum penicillinase-resistant agent that is used against Staphylococcus aureus?
- Methicillin
- Oxacillin
- Cloxacillin (Dicloxacillin)
- Nafcillin
MOCN
What is the half-life of Very-narrow-spectrum penicillinase-resistant agent?
Shorter half-lives
Given 4 times a day, every 6 hours.
This very narrow spectrum penicillase is suitable for treating mild to moderate localized staphylococcal infections.
Isoxazolyl Penicillins (Dicloxacillin)
Isoxazolyl Penicillins (Dicloxacillin) are _ (acid, basic) stable penicillins and have a reasonable bioavailability.
Acid-stable
It is the first antistaphylococcal penicillin to be developed no longer used clinically due to high rates of adverse effects.
Methicillin
What is the drug of choice for serious staphylococcal infections such as endocarditis?
Oxacillin and Nafcillin
What are the Wider spectrum penicillinase-susceptible agent?
- Ampicillin
- Amoxicillin
- Piperacillin
- Ticarcillin
These are wider spectrum than Penicillin G, and enhanced when used with penicillaneses (BLIC).
Amoxicillin and Ampicillin
Route of administration:
Ampicillin is given _ because it degrades in the stomach.
IV
Route of administration:
Amoxicillin is given _.
orally
These are enhanced selectivity against Gr(-), usually combined with penicillinase inhibitors, and administered through IV.
Piperacillin and Ticarcillin
Piperacillin and Ticarcillin enhanced selectivity against Gr(-):
- Pseudomonas
- Enterobacter
- Klebsiella
What are the Extended-Spectrum Penicillins?
- Aminopenicillins
- Carboxypenicillins
- Ureidopenicillins
What is the function of Extended-Spectrum Penicillins?
Enhanced ability to penetrate the Gr(-) outer membrane, and inactivated by many β-lactamases.
Amoxicillin is given in what route of administration?
Orally
250-500 mg
Amoxicillin is used to treat:
- Bacterial sinusitis
- Otitis
- Lower respiratory tract infection
What are the penicillin drugs that are most active of the oral β-lactam antibiotics against pneumococci with elevated MICs and is preferred β-lactam antibiotics for treating infections susespected to be caused by these strains?
Amoxicillin and ampicillin
Ampicillin is effective against susceptible strains of:
Shigella
Ampicillin is useful for treating serious infectious caused by susceptible organisms at dosages of 4-12g/d intravenously, including:
- Anaerobes
- Enterococci
- Lisera monocytogenes
- E. coli
- Salmonella sp
True or False:
Ampicillin can still be used for empiric therapy of UTI and typhoid fever due to the production of β-lactamases by Gr(-) bacilli.
False
Cannot be used.