Beta Lactams & Cell Wall Synthesis Inhibitors Flashcards by BAI JANNAH ABDULKARIM

An antimicrobial drug that can eradicate an infection in the absence of host defense mechanisms; kills bacteria.

Bactericidal

How well did you know this?

Not at all

Perfectly

An antimicrobial drug that inhibits antimicrobial growth but requires host defense mechanisms to eradicate the infection; does not kill bacteria.

Bacteriostatic

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

Bacterial enzymes (penicillinases, cephalosporinases) that hydrolyze the beta-lactam ring of certain penicillins and cephalosporins.

Beta-lactamases

How well did you know this?

Not at all

Perfectly

Potent inhibitors of some bacterial beta-lactamases used in combinations to protect hydrolyzable penicillins from inactivation.

Beta-lactam inhibitors

How well did you know this?

Not at all

Perfectly

Lowest concentration of antimicrobial drug capable of inhibiting growth of an organism in a defined growth medium.

Minimal inhibitory concentration (MIC)

How well did you know this?

Not at all

Perfectly

Bacterial cytoplasmic membrane proteins that act as the initial receptors for penicillins and other beta-lactam antibiotics.

Penicillin-binding proteins (PBPs)

How well did you know this?

Not at all

Perfectly

Chains of polysaccharides and polypeptides that are cross-linked to form the bacterial cell wall

Petptidoglycan

How well did you know this?

Not at all

Perfectly

More toxic to the invader than to the host; a property of useful antimicrobial drugs.

Selective toxicity

How well did you know this?

Not at all

Perfectly

Bacterial enzymes involved in the cross-linking of linear peptidoglycan chains, the final step in cell wall synthesis.

Transpeptidases

How well did you know this?

Not at all

Perfectly

What are the examples of bacteriostatic drugs?

Chloramphenicol
Erthryomycin
Clindamycin
Sulfonamides
Trimethoprim
Tetracyclines

How well did you know this?

Not at all

Perfectly

What are the examples of bactericidal drugs?

Aminoglycosides
Beta-lactams
Vancomycin
Quinolones
Rifampin
Metronidazole

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

What are the major Beta-lactam antibiotics that inhibit cell wall synthesis?

Penicillins
Cephalosporins

How well did you know this?

Not at all

Perfectly

Beta-lactams have the unusual _ member ring that is common to all members.

4-member ring

How well did you know this?

Not at all

Perfectly

What are the general structure of cephalosporins?

Acyc side chain
Beta-lactam ring
Dihydrothiazine ring

How well did you know this?

Not at all

Perfectly

True or False:

Beta-lactam antibiotics are most effective, widely used, and well-tolerated.

True

How well did you know this?

Not at all

Perfectly

What are the not as important beta-lactam drugs?

Vancomycin
Fosfomycin
Bacitracin

How well did you know this?

Not at all

Perfectly

These are the drugs that inhibits the growth/replication or kill microorganisms, they are classified under chemotherapeutic drugs.

Antimicrobials

How well did you know this?

Not at all

Perfectly

What are the following components in bacterial structure?

Cell membrane
Cell wall
Nucleus
Fimbriae
Pili
Ribosomes
Capsule

How well did you know this?

Not at all

Perfectly

What are the components of peptidoglycan bacterial cell wall?

N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)

How well did you know this?

Not at all

Perfectly

Identify if Gr(+) or Gr(-):

Thick peptidoglycan

Gr(+)

How well did you know this?

Not at all

Perfectly

Identify if Gr(+) or Gr(-):

Thin peptidoglycan

Gr(-)

How well did you know this?

Not at all

Perfectly

True or False:

Peptidoglycans are slightly more hydrophilic compared to the outer membrane.

True

How well did you know this?

Not at all

Perfectly

# 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?

1. L-alanine 2. D-glutamine 3. L-lysine 4. 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?

1. Penicillin 2. Cephalosporin 3. Monobactam 4. 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?

1. Thiazolidine ring 2. 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?

1. Glomerular filtration 2. 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?

1. **Bactericidal** drugs 2. Inhibit **cell wall synthesis** 3. Inhibit bacterial growth by interfering with the **transpeptidation reaction**

What are the mechanism of resistance against Penicillin?

1. Hydrolysis of β-lactam ring by bacterial β-lactamases (inactivation) 2. Modification of PBP 3. Changes in membrane permeability 4. 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?

1. Penicillin G 2. 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:

1. **Poor** bioavailability 2. Need for dosing **4 times a day** 3. **Narrow** antibacterial spectrum

What are the Very-narrow-spectrum penicillinase-resistant agent that is used against *Staphylococcus aureus*?

* Methicillin * Oxacillin * Cloxacillin (Dicloxacillin) * Nafcillin ## Footnote 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.

# 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 ## Footnote Cannot be used.

Ampicillin are not active against:

* *Klebsiella sp* * *Enterobacter sp* * *Pseudomonas aeuroginosa* * *Citrobacter sp* * *Serratia marcescens* * Indole-positive *Proteus* species

What are the toxicity/adverse effects of Penicillins?

* Allergy * GI disturbances

# True or False: If a patient has an allergic reaction to Amoxicillin, then they are also allergic to Ampicillin and Oxacillin. This is the **cross-reactivity** of penicillins.

True

Large doses of pencillins given orally may lead to:

GI disturbances | Gastrointestinal upset

GI disturbances is associated with the development of *colitis* due to what type of infection?

*Clostridioides difficile* infection

Adverse effect of **interstitial nephritis** is associated with:

Methicillin

Adverse effect of **neutropenia** is associated with:

Nafcillin

Adverse effect of **skin rashes** in the **setting of viral illness** associated with:

Ampicillin

Adverse effect of **hepatitis** is associated with:

Oxacillin

The greater incidence of **acute kidney injury** when **combined with vancomycin** is associated with:

Piperacillin-tazobactam

Penicillin skin testing may also be used to evaluate what type of hypersensitivity?

Type I hypersensitivity

Who was the pharmacologist that isolated Cephalosporin C compound from the fungus Acremonium?

Giuseppe Brotzu

The fungus Acremonium, previously known as "Cephalosporium" was found in the:

Sea near a sewage outfall in Su Siccu, by Cagliari harbo in Sardinia, Italy

What is the derivatives of Cephalosporins?

7-aminocephalosporanic acid

# True or False: Cephalosporins are **more stable** to many bacterial β-lactamases.

True

# True or False: Cephalosporins is **not active** against *Listeria monocytogenes.*

True

# True or False: Only **ceftaroline** has some activity against *Enterococci.*

True

# True or False: Cephalosporins have **two sites of attachment** for **various R1 and R2** groups.

True

What is the function of **7-position** in Cephalosporins structure?

Alters **antibacterial activity**

What is the function of **3-position** in Cephalosporins structure?

Modifies **pharmacokinetic profile**

# Cephalosporins pharmacokinetics: What is the route of administration of Cephalosporins?

# Cephalosporins pharmacokinetics: Major elimination is through:

Renal excretion

# Cephalosporins pharmacokinetics: What are the drugs that excretes through the bile?

* Cefoperazone * Ceftriaxone | 3rd generation drugs.

# Cephalosporins pharmacokinetics: What are the generations that **do not cross BBB** even in **inflamed meninges**?

1st and 2nd generation

# Cephalosporins pharmacokinetics: The older generation is administered:

orally

# Cephalosporins pharmacokinetics: The newer generation is administered through:

IV or IM

What is the mechanism of action and resistance of Cephalosporins?

1. Bind to **PBP** 2. **Bactericidal** 3. Structural differences render them **less susceptible to penicillinases** produced by staphylococci 4. **MRSA**: Resistant

What are the toxicity/adverse effects on Cephalosporins?

* **Allergy** (rashes to anaphylactic shock) * Complete **cross-reactivity**

What is the percentage of cross-reactivity between penicillin and cephalosporin?

5-10%

These 1st generation drugs are very active against **Gr(+) cocci** such as streptococci and staphylococci, *E.coli*, and *K. pneumoniae*

* Cefazolin * Cephalexin

# 1st generation drugs: Cephalexin is administered:

orally

# 1st generation drugs: Cefazolin is administered:

intravenously

What are the coverage of 1st generation cephalosporins drugs?

* Gr(+) cocci * *E.coli* * *K. pneumoniae* * *Proteus mirabilis*

This first generation drug penetrates well into the **bone**, has **longer duration of action**, and a **similar spectrum of action** compared to other first-generations. | It is also the drug of choice for **surgical prophylaxis.**

Cefazolin

These first-generation drugs is administered **orally twice** daily, a **prototype of first generation** oral cephalosporins, and effective against **pharyngitis.**

* Cefadroxil * Cephalexin

What are the clinical uses of 1st generation cephalosporins drugs?

* UTIs * Staphylococcal/streptococcal infections * Cellulitis * Soft tissue abscess

What is the coverage of 2nd generation cephalosporins drugs?

* Same as 1st gen * Extended Gr(-) activity * *Klebsiella* * *H. influenzae* * *Bacteroides fragilis* * *Serratia*

What are the second-generation drugs that have **anaerobic coverage**, and is active against *Serratia* and *B. fragilis*? ## Footnote Anaerobic: * Peritonitis * Diverticulitis * Pelvic inflammatory disease

Cefotetan Cefoxitin

This second-generation drug has **longer half-life**, crosses the BBB and can be used for **community-acquired bronchitis** or **pneumonia** in the elderly and for immunocompromised.

Cefuroxime sodium

This second-generation drug is administered **twice daily**, **well-absorbed**, and **active against β-lactamase-producing** organisms.

Cefuroxime axetil

This second-generation drug **improves stability** in the presence of extended-spectrum β-lactamases produced by *E.coli* and *Klebsiella sp.*

Cefoxitin

What are the second-generation drugs that are active against *H. influenzae?*

* Cefuroxime * Cefaclor

# 2nd generation drugs: Cefuroxime is administered:

orally

What are the coverage of 3rd generation cephalosporins drugs?

* Expanded Gr(-) * *Citrobacter* * *S. marcescens* * *P. aeruginosa* (by ceftazidime only) * *Providencia* * β-lactamase-producing strains of *Haemophilus* and *Neisseria*

This third-generation drug is the regimen of choice for treating most **gonococcal infections**, and excreted through the **bile.**

Ceftriaxone

What is the third-generation drug that penetrated well into the CSF?

Cefotaxime

What are the third-generation drugs that is administered orally once daily?

* Cefdinir * Cefixime

What are the clinical uses of 3rd generation cephalosporins drugs?

Treat **serious infections** caused by organisms that are resistant to most other drugs.

What are the coverage of fourth-generation cephalosporins?

* *P. aeruginosa* * *Enterobacteriaceae* * MRSA * *S. pneumoniae* * *Haemophilus* & *Neisseria spp* * Penicillin-non susceptible stretococci strains

# True or False: Cefepime penetrates well into CSF.

True

# 4th generation drugs: Cefepime is excreted through:

renal

# 4th generation drugs: What is the half-life of Cefepime?

2 hours

What are the clinical uses of 4th generation drugs?

* *Enterobacter* infections * Empiric therapy for pt. with **febrile neutropenia**

This β-lactam drug has monocyclic β-lactam ring. Their spectrum of activity is limited to **aerobic Gr(-) organisms.**

Monobactam

What is the only available monobactam?

Aztreonam

# True or False: Aztreonam has structural similarities with **ceftazidime.**

True

# True or False: Aztreonam penetrates well into CSF.

True

# Monobactam: Aztreonam is administered:

intravenously ## Footnote every 8 hours in a dose of 1-2 g

# Monobactam: What is the half-life of Aztreonam?

1-2 hours

# Monobactam: What are the clinical uses of Monobactam?

* Pneumonia * Meningitis * Sepsis caused by susceptible Gr(-) pathogens

# True or False: **Penicillin-allergic** patients **tolerate** Aztreonam **without reaction.**

True

What are the Traditional β-lactamase inhibitors?

* Clavulanic acid * Sulbactam * Tazobactam

What are the Novel Non-β-lactam β-lactamase Inhibitors?

* Avibactam * Vaborbactam

# Identify if Traditional or Novel: Resemble β-lactam-lactam molecules but have **weak antibacterial action.**

Traditional β-lactamase inhibitors

# Identify if Traditional or Novel: Can **protect hydrolyzable penicillins from inactivation** by these enzymes.

Traditional β-lactamase inhibitors

# Identify if Traditional or Novel: Most active against Amber class A β-lactamases, but not good inhibitors of class C β-lactamases.

Traditional β-lactamase inhibitors

# Identify if Traditional or Novel: Active against Amber class A and Amber class C β-lactamases.

Novel Non-β-lactam β-lactamase Inhibitors

What are the Carbapenems available?

* Doripenem * Ertapenem * Imipenem * Meropenem

What are the coverage of Carbapenems?

* Gr(-) rods [*P. aeruginosa*] * Gr(+) organisms * Anaerobes

Carbapenems are resistant to:

* Most β-lactamases * ESBL

Carbapenemes are administered:

intravenously

# True or False: Carbapenems penetrates body tissues and fluids including CSF, except for **ertapenem.**

True

Carbapenems is excreted through:

Renal

# Identify the carbapenem: Dosage: 0.5 g in a 1 to 4-hour infusion every 8 hours

Doripenem

# Identify the carbapenem: Longest half-life (4 hours)

Ertapenem

# Identify the carbapenem: Not sufficiently active against *P.aeruginosa.*

Ertapenem

# Identify the carbapenem: Dosage: once-daily dose of 1 g through IV or IM.

Ertapenem

# Identify the carbapenem: Has a wide spectrum with good activity against most: * Gr(-) rods * Gr(+) organisms * Anaerobes

Imipenem

# Identify the carbapenem: Combined with **cilastatin**, which inhibits **dehydropeptidases** enzymes in renal tubules.

Imipenem

# Identify the carbapenem: Dosage: 0.25-0.5 g through IV every 6-8 hours

Imipenem

# Identify the carbapenem: Similar to imipenem but **slightly higher activity** against Gr(-) aerobes and **slightly lower activity** against Gr(+)

Meropenem

# Identify the carbapenem: Not significantly degraded by renal dehydropeptidase, and does not require an inhibitor.

Meropenem

# Identify the carbapenem: Dosage: 0.5 g IV every 8 hours

Meropenem

What are the Glycopeptide Antibiotics?

* Vancomycin * Telavancin * Dalbavancin and Oritavancin

# Identify the glycopeptide antibiotics: **Water-soluble** and **stable for 14 days** in the refrigerator following reconstitution.

Vancomycin

Vancomycin was isolated from the bacterium called?

*Amycolatopsis orientalis*

What are the coverages of Vancomycin?

* Bactericidal against Gr(+) and anaerobes (i.e. *Enterococcus faecium* * Active against MRSA

What is the mechanism of action of Vancomycin?

1. **Binds to D-Ala-D-Ala terminal** of nascent peptidoglycan pentapeptide 2. **Inhibits transglycosylase** through preventing elongation of peptidoglycan and cross-linking 3. **Weakens peptidoglycan** thus making cell **susceptible to lysis.**

What are the resistance of Vancomycin?

* Terminal D-ala is replaced by D-lactate * Loss of critical hydrogen bond * Loss of activity

Vancomycin is administered _ only for the treatment of **colitis** caused by *C. difficile.*

orally

Vancomycin is _ (poorly, fully) absorbed from the intestinal tract.

poorly absorbed

Vancomycin is widely dristributed in the body including _ tissue.

adipose

Vancomycin is excreted through:

glomerular filtration by 90%

What are the adverse reactions associated with Vancomycin?

* Phlebitis * Chills & fever * Ototoxicity * Nephrotoxicity * **Red man syndrome**

Red man syndrome is caused by the released of _, and can be prevented by slowing down the adminsitration of Vancomycin.

histamine

# Identify the glycopeptide antibiotics: Semisynthetic lipoglycopeptide derived from Vancomycin.

Telavancin

What are the coverage of Telavancin?

* Gr(+) * In-vitro activity against many strains with reduced susceptibility to Vancomycin

What is the half-life of Telavancin?

8 hours

What is the mechanism of action of Telavancin?

1. **Inhibits cell wall synthesis** by binding to D-Ala-D-Ala terminus of peptidoglycan in the growing cell wall. 2. **Increases membrane permeability** and disrupts the bacterial cell membrane potential.

What are the adverse reactions associated with Telavancin?

* Nephrotoxicity * Teratogenic * Not administered to a pregnant women

# Identify the glycopeptide antibiotics: Semisynthetic lipoglycopeptides derived from teicoplanin.

Dalbavancin and Oritavancin

What is the mechanism of action of Dalbavancin and Oritavancin?

1. **Inhibits cell wall synthesis** by binding to D-Ala-D-Ala terminus of peptidoglycan pentapeptide which **prevents cross-linking.** 2. Oritavancin disrupts cell membrane permeability and inhibits RNA synthesis.

Dalbavancin and Oritavancin have lower MICs against many Gr(+) bacteria, including?

* Methicillin-resistant * Vancomycin-resistant *S. aureus*

What is the half-life of Dalbavancin and Oritavancin?

Long half-lives; extremely more than 10 days

What are the other cell wall or membrane-active agents?

* Daptomycin * Fosfomycin * Bacitracin * Cycloserine

Daptomycin is a **lipopeptide fermentation product** of?

*Streptomyces roseosporus*

Daptomycin is excreted through:

renal

What is the mechanism of action of Daptomycin?

1. Bind the cell membrane via **calcium-dependent insertion** of its lipid tail 2. Depolarization of the cell membrane with **potassium efflux** and **rapid cell death.**

What are the adverse effects of Daptomycin?

* **Myopathy** * Allergic pneumonitis if prolonged therapy for >2 weeks * **Pulmonary surfactant antagonist**, should not be used to treat pneumonia

Fosfomycin is an **antimetabolite inhibitor** of __ __ by covalently binding to the cysteine residue of the active site.

enolpyruvate transferase

Fosfomycin becomes **synergistic** (in-vitro) when combined with:

* β-lactam antibiotics * Aminoglycosides * Fluoroquinolones

Fosfomycin is excreted through:

renal

What are the clinical uses of Fosfomycin?

* Safe for pregnancy * Uncomplicated cystitis (UTI)

Bacitracin is obtained from the Tracy strain of?

*Bacillus subtilis*

What is the mechanism of action of Bacitracin?

1. Inhibits **cell wall formation** by interfering with **dephosphorylation** in the cycling of lipid carrier that **transfers peptidoglycan** subunits to the growing cell wall. 2. No cross-resistance between other antimicrobial drugs.

What are the adverse effects associated with Bacitracin?

* Highly nephrotoxic * Associated with hypersensitivity

What is the clinical use of Bacitracin?

Topical antibiotic (ointment)

Cycloserine is produced by?

*Streptomyces orchidaceous*

What are the characteristics of Cycloserine?

1. Water-soluble 2. Unstable at acid pH

Cycloserine is the structural analog of?

D-Alanine

What is the mechanism of action of Cycloserine?

1. **Inhibits incorporation of D-Alanine into peptidoglycan pentapeptide** by inhibiting **alanine racemase.**

Cycloserine is excreted through:

urine

What is the clinical use of Cycloserine?

Treatment of **tuberculosis** caused by strains of *Mycobacterium tuberculosis* resistant to first-line agents.

What are the adverse effects associated with Cycloserine?

* Headaches * Tremors * Acute psychosis * Convulsions

Beta Lactams & Cell Wall Synthesis Inhibitors Flashcards

comprehensive (206 cards)