antibiotics cell wall inhibitors

first generation CEPHALOSPORINS

• Cefadroxil

• cefazolin

• cephalexin

• cephalothin

• cephapirin

• cephradine

Moa

TARGET GRAM POSITIVE COCCI

side effects

• Gi upset

• rash

• anaphylaxis

2nd generation CEPHALOSPORINS

Types

• cefaclor

• cefprozil

• cefmetazole

• cefotetan

• cefoxitin

Use

effective against many gram-positive and gram-negative organisms

Side Effects

• GI upset

• yeast infection

• allergic reactions

• bleeding risk (cefotetan and cefamandole)

Beta-Lactam Antibiotics (Penicillins, Cephalosporins, Carbapenems, Monobactams)

What do they do?

• Inhibit bacterial cell wall synthesis

• bactericidal

How do they work?

• Bind to Penicillin-Binding Proteins (PBPs) (transpeptidase enzymes)

• Prevent cross-linking of peptidoglycan in the bacterial cell wall

• Result: weakened cell wall → bacterial death

Drug Examples:

• Penicillins: Amoxicillin, Penicillin G

• Cephalosporins: Cefazolin, Ceftriaxone

• Carbapenems: Meropenem, Imipenem

• Monobactams: Aztreonam

Nursing Side Effects:

• GI upset

• Rash

• Allergic reactions

• Anaphylaxis (serious)

Penicillins

What do they do?
Treat MAINLY gram-positive and some gram-negative bacterial infections.

Mechanism of Action:

• Beta-lactam antibiotic

• Binds PBPs and inhibits bacterial cell wall synthesis

Examples:

• Penicillin G

• Amoxicillin

• Ampicillin

Major Side Effects:

• GI upset (nausea, vomiting, diarrhea)

• Rash

• Allergic reactions

• Anaphylaxis

Cephalosporins

What do they do?
Treat a broad range of bacterial infections.

Mechanism of Action:

• Beta-lactam antibiotic

• Inhibits bacterial cell wall synthesis by binding PBPs

Examples:

• Cefazolin (1st gen, post surgery)

• Cephalexin (1st gen skin&tissue, UTI’S)

• Ceftriaxone (3rd gen, STI’S)

Major Side Effects:

• Nausea

• Vomiting

• Diarrhea

• Rash

• Allergic reactions

Nursing Tip:
Use cautiously in patients with severe penicillin allergies.

Carbapenems

What do they do?
Broad-spectrum antibiotics used for serious infections.

Mechanism of Action:

• Beta-lactam antibiotic

• Inhibits cell wall synthesis

• Naturally resistant to many beta-lactamases

Examples:

• Meropenem

• Imipenem

• Ertapenem

Major Side Effects:

• Nausea

• Vomiting

• Diarrhea

• Allergic reactions

Key Point:
do not need beta-lactamase inhibitors

Monobactams

What do they do?
Treat gram-negative bacterial infections.

Mechanism of Action:

• Beta-lactam antibiotic

• Inhibits bacterial cell wall synthesis

• Resistant to many beta-lactamases

Example:

• Aztreonam

Major Side Effects:

• Nausea

• Vomiting

• Diarrhea

• Allergic reactions

Key Point:
do not need beta-lactamase inhibitors.

Beta-Lactamase Inhibitors

What do they do?
Protect beta-lactam antibiotics from bacterial destruction.

Mechanism of Action:

• Irreversibly bind and inhibit beta-lactamase enzymes

• Prevent breakdown of the beta-lactam ring

Examples:

• Clavulanic acid

• Sulbactam

• Tazobactam

• Avibactam

Common Combinations:

• Amoxicillin + Clavulanate

• Piperacillin + Tazobactam

Nursing Side Effects:

• GI upset (nausea, vomiting, diarrhea)

• Allergic reactions (usually related to the beta-lactam antibiotic)

Beta-Lactam Resistance

Most Common Resistance Mechanism:

• Production of beta-lactamase enzymes

What do beta-lactamases do?

• Break the beta-lactam ring

• Inactivate the antibiotic

How is resistance overcome?

• Combine beta-lactam antibiotics with beta-lactamase inhibitors

Examples:

• Amoxicillin + Clavulanate

• Piperacillin + Tazobactam

3 abx that penetrate the BBB when inflammation is present

1. Cefotaxime (3rd generation, target gram-)
2. Ceftriaxone (3rd generation, gram -)
3. Ceftazidime (3rd generation, gram-)
-penetrate when inflammation is present

Fosfomycin

Drug Class:

• Cell wall synthesis inhibitor

What does it do?

• Prevents formation of peptidoglycan precursors needed to build the bacterial cell wall

• Causes bacterial cell death

Mechanism of Action:

• Irreversibly inhibits MurA enzyme

• Blocks the first step of bacterial cell wall synthesis

Major Side Effects:

• Nausea

• Diarrhea

• Dizziness

• Headache

NCLEX Tip:
"Fosfomycin = First step blocked

Cycloserine (Cell wall synthesis inhibitor)

What does it do?

• Prevents production of D-alanine needed for peptidoglycan formation

• Causes bacterial cell death

Mechanism of Action:

• Competitively inhibits:

  • D-alanine racemase

  • D-alanine:D-alanine ligase

• Stops formation of peptidoglycan precursors

Major Side Effects:

• Peripheral neuropathy

• Depression

• Psychosis

• Other neurologic disturbances

Nursing Consideration:
Monitor for mental status changes and neurologic symptoms.

NCLEX Tip:
"CycloSERINE affects the SERIOUS nervous system."

Vancomycin

Drug Class:

• Glycopeptide antibiotic

• Cell wall synthesis inhibitor

What does it do?

• Prevents proper assembly of the bacterial cell wall

• bactericidal

Mechanism of Action:

• Binds to D-alanine-D-alanine residues

• Inhibits:

  • Transpeptidation

  • Transglycosylation

• Prevents peptidoglycan cross-linking

Major Side Effects:

• Red Man Syndrome

• Hypotension

• Nephrotoxicity

• Ototoxicity

• Neutropenia

Nursing Consideration:

• Infuse IV vancomycin slowly.

• Monitor kidney function and hearing.

NCLEX Tip:
VAN = Very toxic to Auditory system and Nephrons

Red Man Syndrome (Vancomycin)

Cause:

• Rapid IV infusion of vancomycin

Signs & Symptoms:

• Flushing of face, neck, and upper body

• Redness

• Hypotension

Nursing Intervention:

• Slow the infusion rate

• Monitor blood pressure

Key Point:
This is the most tested adverse effect of IV vancomycin.

Bacitracin (Cell wall synthesis inhibitor)

Drug Class:

• Cell wall synthesis inhibitor

What does it do?

• Prevents bacterial cell wall construction

• Causes bacterial death

Mechanism of Action:

• Binds to bactoprenol

• Prevents regeneration of the transport protein needed to move peptidoglycan components

Major Side Effects (Topical):

• Mild skin irritation

Major Side Effects (IV):

• Nausea

• Vomiting

• Allergic reactions

• Nephrotoxicity

Nursing Consideration:
Topical use is generally well tolerated; IV administration carries higher toxicity risk.

Cell Wall Synthesis Inhibitors: Key Side Effects

Drug	Most Important Side Effect
Fosfomycin	Nausea, diarrhea, headache, dizziness
Cycloserine	Peripheral neuropathy, depression, psychosis
Vancomycin	Red Man Syndrome, nephrotoxicity, ototoxicity
Bacitracin	Nephrotoxicity (IV), skin irritation (topical)

Cell Wall Inhibitors (Non-Beta-Lactams)

Drug	MOA	Major Side Effect
Fosfomycin	Inhibits MurA	GI upset, headache
Cycloserine	Blocks D-alanine formation	Neurologic/psychiatric effects
Vancomycin	Binds D-Ala-D-Ala	Red Man Syndrome, nephrotoxicity, ototoxicity
Bacitracin	Binds bactoprenol	Nephrotoxicity (IV)

Mycobacterial Cell Wall Inhibitors

What do they treat?

• Tuberculosis (TB)

• Other mycobacterial infections

Major Drugs:

• Isoniazid (INH)

• Ethambutol

What do they do?

• Disrupt the unique mycobacterial cell wall

• Cause bacterial death or inhibit growth

NCLEX Tip:
Mycobacteria have a mycolic acid-rich cell wall, making them resistant to many antibiotics

Isoniazid (INH) (Mycobacterial cell wall inhibitor)

What does it do?

• Inhibits synthesis of mycolic acid

• Weakens the mycobacterial cell wall

• Leads to bacterial death

Mechanism of Action:

• Prodrug activated by bacterial enzyme KatG

• Inhibits InhA (enoyl-acyl carrier protein reductase)

• Blocks mycolic acid production

Major Side Effects:

• Hepatotoxicity

• Peripheral neuropathy

Nursing Considerations:

• Monitor liver function tests (LFTs)

• Assess for numbness and tingling in hands and feet

• Vitamin B6 (pyridoxine) is often given to prevent neuropathy

NCLEX Memory Trick:
"INH Injures Neurons and Hepatocytes."

Isoniazid (INH): Major Nursing Concern

Most Important Adverse Effects:

1. Hepatotoxicity

2. Peripheral Neuropathy

Signs of Hepatotoxicity:

• Jaundice

• Dark urine

• Fatigue

• Elevated liver enzymes

Signs of Peripheral Neuropathy:

• Numbness

• Tingling

• Burning sensation in hands and feet

Nursing Intervention:

• Administer Vitamin B6 (Pyridoxine) as prescribed

Ethambutol (Mycobacterial cell wall inhibitor)

What does it do?

• Disrupts formation of arabinogalactan in the mycobacterial cell wall

• Increases cell wall permeability

Mechanism of Action:

• Inhibits Arabinosyl Transferase (EmbB)

• Prevents polymerization of arabinose into arabinogalactan

Major Side Effect:

• Optic neuritis

Nursing Consideration:

• Monitor visual acuity

• Monitor color vision

• Report vision changes immediately

Ethambutol: Most Tested Side Effect

Adverse Effect:

• Optic neuritis

Symptoms:

• Blurred vision

• Decreased visual acuity

• Color vision changes (especially red-green discrimination)

• Potential vision loss

Nursing Action:

• Baseline eye exam

• Regular vision monitoring

Isoniazid vs. Ethambutol

Drug	Mechanism	Major Side Effect
Isoniazid (INH)	Inhibits mycolic acid synthesis	Hepatotoxicity, peripheral neuropathy
Ethambutol	Inhibits arabinogalactan synthesis	Optic neuritis, vision loss

how do cephalosporins affect bleeding?

-increase risk of bleeding
-NMTT structure in some cephalosporins inhibits certain hepatic enzymes used to make coagulation factors

Cell Membrane Integrity Disruptors

What do they do?

• Damage bacterial cell membranes

• Cause leakage of cellular contents

• Lead to bacterial death

Major Drugs:

• Daptomycin

• Polymyxins

NCLEX Tip:
Unlike beta-lactams and vancomycin, these drugs target the cell membrane, not the cell wall.

Daptomycin (Cell membrane integrity disruptor)

What does it do?

• Creates pores in the bacterial cell membrane

• Causes ion leakage and bacterial death

Mechanism of Action:

• Binds with calcium

• Inserts into gram-positive bacterial cell membranes

• Forms pore-like channels

• Causes potassium leakage and membrane depolarization

Major Side Effect:

• Skeletal muscle toxicity (myopathy)

Nursing Considerations:

• Monitor for muscle pain or weakness

• Monitor creatine kinase (CK/CPK) levels

NCLEX Memory Trick:
"DAPTO = Damages muscles."

Polymyxins (Cell membrane integrity disruptor)

What do they do?

• Destroy gram-negative bacterial membranes

• Cause leakage of cell contents and bacterial death

Mechanism of Action:

• Bind to lipopolysaccharides (LPS) on gram-negative bacteria

• Increase membrane permeability

• Disrupt inner cell membrane

Examples:

• Polymyxin B

• Colistin (Polymyxin E)

Major Side Effects:

• Nephrotoxicity

• Neurotoxicity

Daptomycin: Major Nursing Concern

Serious Adverse Effect:

• Skeletal muscle toxicity

Symptoms:

• Muscle pain

• Muscle weakness

• Elevated CK (CPK)

Nursing Action:

• Monitor CK levels regularly

• Report unexplained muscle pain or weakness

NCLEX Favorite:
Daptomycin → Myopathy

Polymyxins: Major Nursing Concerns

Serious Adverse Effects:

🩺 Nephrotoxicity

• Increased creatinine

• Decreased urine output

• Kidney injury

🧠 Neurotoxicity

• Dizziness

• Weakness

• Paresthesias (numbness/tingling)

Nursing Action:

• Monitor renal function

• Assess neurologic status

Daptomycin vs Polymyxins

Drug	Target	Major Side Effect
Daptomycin	Gram-positive cell membrane	Skeletal muscle toxicity
Polymyxins	Gram-negative cell membrane	Nephrotoxicity, neurotoxicity

Which Cell membrane integrity disruptor Causes Muscle Toxicity?

Daptomycin

third generation cephalosporins

Types

• ceftriaxone

• ceftazidime (Pseudomonas)

• cefdinir

• cefpodoxime

• cefoperazone

• cefixime

Uses

effective against gram negative bacteria. Used for STI’S

Side effects

• GI upset

• allergic reactions

• superinfections or severe colitis (Clostridium difficile)

Interactions

• Increased effectiveness with probenecid

• Disulfiram-like reactions (flushing, tachycardia, shock) with alcohol ingestion and cefotetan

fourth generation cephalosporins

Types

• Cefepime (Maxipime)

Uses

excellent against both gram-positive and gram-negative bacteria. Penetrates cerebrospinal fluid, reserved for resistant infections

Side effects

• GI upset

• allergic reactions

• superinfections or severe colitis (Clostridium difficile)

Interactions

• Increased effectiveness with probenecid

• Disulfiram-like reactions (flushing, tachycardia, shock) with alcohol ingestion and cefotetan

fifth generation cephalosporin

Types

Ceftaroline (Teflaro)

Uses

active against resistant gram-positive pathogens, including MRSA and vancomycin-resistant S. aureus (VRSA).

Covers Listeria monocytogenes and Enterococcus faecalis

Side Effects

• GI upset

• allergic reactions

• superinfections or severe colitis (Clostridium difficile)

Interactions

• Increased effectiveness with probenecid

• Disulfiram-like reactions (flushing, tachycardia, shock) with alcohol ingestion and cefotetan