Cell Wall Synthesis Inhibitors Part 3

Penicillins are most active against

Gram-positive bacteria.

Natural penicillins are highly active against

Streptococcus spp.

Penicillins have activity against

Some Gram-negative bacteria, anaerobes, and spirochetes.

Major veterinary use of penicillins

Respiratory, skin, soft tissue, and systemic infections.

Penicillins are generally distributed widely throughout the body.

Penicillins penetrate poorly into

The CNS.

Main route of elimination of penicillins

Renal excretion.

Most common adverse reaction to penicillins

Hypersensitivity reactions.

Examples of penicillin hypersensitivity

Urticaria, fever, anaphylaxis, and skin eruptions.

Penicillins may cause

Diarrhea due to alteration of intestinal flora.

Most important resistance mechanism to penicillins

Beta-lactamase production.

Beta-lactamases destroy

The beta-lactam ring.

Cephalosporins generally have broader Gram-negative activity than

Penicillins.

First-generation cephalosporins are most active against

Gram-positive bacteria.

Examples of first-generation cephalosporins

Cefazolin and Cephalexin.

Second-generation cephalosporins have

Increased Gram-negative activity.

Examples of second-generation cephalosporins

Cefuroxime and Cefoxitin.

Third-generation cephalosporins have

Excellent Gram-negative activity.

Examples of third-generation cephalosporins

Ceftiofur, Cefotaxime, and Ceftriaxone.

Fourth-generation cephalosporins have

Enhanced Gram-negative activity and beta-lactamase resistance.

Example of a fourth-generation cephalosporin

Cefepime.

Most important veterinary third-generation cephalosporin

Ceftiofur.

Main veterinary use of ceftiofur

Respiratory disease and systemic infections.

Cephalosporins are generally resistant to

Many beta-lactamases.

Cephalosporins distribute widely into body tissues.

Most cephalosporins are eliminated by

The kidneys.

Common adverse effects of cephalosporins

Hypersensitivity reactions and GI disturbances.

Cross-reactivity may occur between

Penicillins and cephalosporins.

Monobactams are active primarily against

Aerobic Gram-negative bacteria.

Aztreonam is especially active against

Enterobacteriaceae and Pseudomonas.

Aztreonam has little to no activity against

Gram-positive bacteria and anaerobes.

Major advantage of aztreonam

Resistance to most beta-lactamases.

Aztreonam is distributed widely in the body.

Aztreonam penetrates well into

The cerebrospinal fluid.

Main route of aztreonam elimination

Renal excretion.

Common adverse effects of aztreonam

Generally mild GI disturbances and local reactions.

Carbapenems possess

The broadest spectrum among beta-lactams.

Carbapenems are active against

Gram-positive, Gram-negative, and anaerobic bacteria.

Examples of carbapenems

Imipenem, Meropenem, and Ertapenem.

Carbapenems are reserved for

Severe or multidrug-resistant infections.

Carbapenems are highly resistant to

Many beta-lactamases.

Carbapenems distribute widely throughout the body.

Meropenem penetrates well into

The CNS.

Main route of elimination of carbapenems

Renal excretion.

Major adverse effect of carbapenems

Seizures at high doses.

Imipenem is commonly combined with

Cilastatin.

Purpose of cilastatin

Prevents renal degradation of imipenem.

Vancomycin spectrum

Primarily Gram-positive bacteria.

Vancomycin is highly active against

Staphylococci and streptococci.

Vancomycin is effective against

Methicillin-resistant Staphylococcus aureus (MRSA).

Vancomycin has little activity against

Gram-negative bacteria.

Vancomycin is considered a

Reserve antibiotic.

Reason vancomycin is a reserve antibiotic

To preserve activity against resistant organisms.

Vancomycin is poorly absorbed orally.

Oral vancomycin is used mainly for

Clostridioides difficile infections.

Vancomycin distributes well into most tissues.

Vancomycin penetration into CSF improves

When meninges are inflamed.

Main route of elimination of vancomycin

Renal excretion.

Major toxicity of vancomycin

Nephrotoxicity.

Additional toxicity of vancomycin

Ototoxicity.

Rapid IV administration of vancomycin may cause

Red man syndrome.

Red man syndrome is characterized by

Flushing, erythema, and hypotension.

Most important resistance mechanism to vancomycin

Alteration of target binding sites.

Bacitracin spectrum

Primarily Gram-positive bacteria.

Bacitracin is active against

Staphylococci, streptococci, and clostridia.

Bacitracin has poor activity against

Most Gram-negative bacteria.

Systemic use of bacitracin is limited by

Nephrotoxicity.

Bacitracin is most commonly used

Topically.

Common topical uses of bacitracin

Skin, eye, and ear infections.

Bacitracin is often combined with

Neomycin and polymyxin B.

Main route of elimination of bacitracin

Renal excretion.

Major toxicity of bacitracin

Nephrotoxicity.

Fosfomycin spectrum

Broad spectrum.

Fosfomycin is active against

Gram-positive and Gram-negative bacteria.

Fosfomycin is particularly useful against

Multidrug-resistant organisms.

Fosfomycin distributes widely into tissues.

Fosfomycin penetrates well into

Urine and tissues.

Main route of elimination of fosfomycin

Renal excretion.

Fosfomycin is generally well tolerated.

Most common adverse effects of fosfomycin

GI disturbances.

Most important resistance mechanism to fosfomycin

Reduced uptake into bacterial cells.

Cell wall inhibitors work best against

Actively growing bacteria.

Bacteriostatic drugs may antagonize

Beta-lactam antibiotics.

Reason bacteriostatic drugs antagonize beta-lactams

Beta-lactams require active bacterial growth.

High-yield association

Ceftiofur = Third-generation cephalosporin.

High-yield association

Aztreonam = Monobactam.

High-yield association

Imipenem = Carbapenem.

High-yield association

Meropenem = Carbapenem with CNS penetration.

High-yield association

Vancomycin = MRSA.

High-yield association

Bacitracin = Topical use.

High-yield association

Fosfomycin = PEP analogue.

High-yield association

Red man syndrome = Vancomycin.

High-yield association

Cilastatin = Protects imipenem.

High-yield association

Beta-lactamase production = Penicillin resistance.

High-yield association

Altered PBPs = Beta-lactam resistance.

High-yield association

Altered binding site = Vancomycin resistance.

Most important exam organism for vancomycin

MRSA.

Most important exam use for ceftiofur

Respiratory disease.

Most important exam toxicity of bacitracin

Nephrotoxicity.

Most important exam toxicity of vancomycin

Red man syndrome.