Antibiotic Pharmacology: Classes, Mechanisms, Resistance, and Adverse Effects

What are antibiotics?

Compounds that inhibit the growth of bacteria without harming the host.

What is the importance of antibiotic spectrum?

It helps identify the range of bacteria the drug can treat: narrow, broad, or extended.

What is a narrow spectrum antibiotic?

An antibiotic effective against one class of bacteria.

What is a broad spectrum antibiotic?

An antibiotic effective against a range of bacteria.

What is an extended spectrum antibiotic?

A narrow spectrum antibiotic modified to be effective against more bacteria.

What does bacteriostatic mean?

An antibiotic that inhibits growth and replication of bacteria.

What does bactericidal mean?

An antibiotic that kills bacteria.

Can an antibiotic be both bacteriostatic and bactericidal?

Yes, one antibiotic can be bacteriostatic for one bacteria and bactericidal for another.

What is antibiotic resistance?

When bacteria evolve to defeat drugs designed to kill them, making infections difficult or impossible to treat.

How can bacteria develop resistance?

Through mutation, adaptation, or gene transfer.

What are plasmids?

Extrachromosomal genetic elements that can be transferred between bacteria and may code for enzymes that inactivate antimicrobials.

What are transposons?

Segments of genetic material that can carry code for enzymes that inactivate antimicrobials and are incorporated into the genetic makeup of bacteria.

What are adverse effects of antibiotics?

Can be allergic, toxic, idiosyncratic, or related to changes in normal body flora.

What are superinfections?

Secondary infections often due to changes in normal flora.

What is synergism in antibiotic therapy?

When two or more antimicrobials work together for a larger/more effective response.

What is culture and sensitivity testing?

A method to determine which antibiotic to use by culturing and identifying the organism.

What does MIC stand for?

Minimum Inhibitory Concentration, the lowest concentration of a drug that inhibits growth of the organism.

What is the disadvantage of culture and sensitivity testing?

It can take several days for cultures to grow and sensitivities to be determined.

What are the two types of dosing schedules for antibiotics?

Time dependent and concentration-dependent.

What is a time-dependent antibiotic?

An antibiotic that is most effective when its blood concentration remains above the MIC.

What is a concentration-dependent antibiotic?

An antibiotic where the peak concentration is most important for determining effectiveness.

What is a post-antibiotic effect?

When an antibiotic continues to be effective even when plasma concentration has fallen below the MIC.

Why is it important to know brand/generic names for antibiotics?

To ensure proper identification and usage in practice.

What is the primary mechanism of action for inhibitors of cell wall synthesis?

They interfere with the transpeptidation process, which is the cross-linking of peptidoglycan strands.

What are penicillin-binding proteins (PBPs)?

Enzymes that catalyze the transpeptidation and cross-linking of peptidoglycan strands in bacterial cell walls.

What are beta-lactam antibiotics named for?

The beta-lactam ring present in their chemical structure.

Which antibiotics are included in the beta-lactam class?

Penicillins, cephalosporins, carbapenems, and monobactams.

What is the main action of beta-lactam antibiotics?

They interfere with the synthesis of the bacterial cell wall.

What is a common mode of resistance against beta-lactam antibiotics?

The production of beta-lactamase enzymes that inactivate the antibiotics.

What is the role of clavulanic acid in antibiotic therapy?

It is a beta-lactamase inhibitor that enhances the effectiveness of beta-lactam antibiotics.

What are the four groups of penicillins?

Natural penicillins, penicillinase-resistant penicillins, aminopenicillins, and extended-spectrum penicillins.

What is the spectrum of natural penicillins?

Narrow spectrum, primarily effective against gram-positive bacteria.

What is the significance of methicillin in penicillin classification?

It is a penicillinase-resistant penicillin used to treat infections caused by penicillin-resistant bacteria.

What are the common combinations of penicillins with beta-lactamase inhibitors?

Amoxicillin/clavulanate (Augmentin), ampicillin/sulbactam (Unasyn), and piperacillin/tazobactam (Zosyn).

What types of allergic reactions can occur with penicillins?

Immediate, accelerated, and late allergic reactions.

What is the spectrum of first-generation cephalosporins?

Narrow spectrum, primarily active against gram-positive bacteria.

What is the primary use of second-generation cephalosporins?

To treat respiratory infections and infections caused by Haemophilus influenzae.

What distinguishes third-generation cephalosporins from earlier generations?

They have broader coverage against gram-negative bacteria and some can cross the blood-brain barrier.

What is a key feature of fourth-generation cephalosporins?

They have extended activity against both gram-positive and gram-negative organisms, including those resistant to earlier generations.

What is the significance of fifth-generation cephalosporins?

They are effective against Methicillin-resistant Staphylococcus aureus (MRSA).

What are common side effects of cephalosporins?

Nausea, diarrhea, and rashes.

What is the mechanism of action for aminoglycosides?

They inhibit protein synthesis in bacteria.

What is the role of folate antagonists in antibiotic therapy?

They inhibit the synthesis of folate, which is necessary for bacterial growth.

What are quinolones primarily used for?

They are broad-spectrum antibiotics effective against a variety of bacterial infections.

What is the significance of the term 'plasmid transfer' in antibiotic resistance?

It refers to the transfer of genetic material that can confer resistance to antibiotics among bacteria.

What is the primary action of beta-lactamase enzymes?

To open the beta-lactam ring of antibiotics, rendering them ineffective.

What is a common treatment strategy for infections caused by beta-lactamase producing bacteria?

Combining beta-lactam antibiotics with beta-lactamase inhibitors.

What effect can some cephalosporins have when used with blood thinners?

They can cause bleeding problems due to anti-vitamin K effects.

What is contraindicated when using cephalosporins, especially in newborns?

Combining cephalosporins with calcium-containing solutions.

What are the three main carbapenems mentioned?

Imipenem, ertapenem (Invanz), and meropenem (Merrem).

What is the role of cilastatin when administered with imipenem?

Cilastatin inhibits renal dipeptidase, preventing imipenem from being hydrolyzed to a toxic metabolite.

Which carbapenem does not require cilastatin?

Meropenem.

What type of bacteria do monobactams primarily target?

Aerobic gram-negative bacteria, such as Escherichia coli and Pseudomonas aeruginosa.

What is aztreonam used for?

It is an alternative in severe beta-lactam allergies and is used with other antibiotics for a synergistic effect.

What is the mechanism of action (MoA) of glycopeptides?

They inhibit cell wall synthesis by preventing polymerization of the linear peptidoglycan.

What is a common side effect of vancomycin when administered too quickly?

Red man syndrome due to histamine release.

What is the primary use of bacitracin?

It is used topically to inhibit cell wall synthesis.

What is fosfomycin used to treat?

Uncomplicated urinary tract infections.

What is the mechanism of action of daptomycin?

It binds to the membrane of bacteria and causes depolarization, leading to cell death.

What are the main classes of protein synthesis inhibitors?

Aminoglycosides, tetracyclines, macrolides, streptogramins, oxazolidinones, chloramphenicol, and clindamycin.

What is a significant risk associated with aminoglycosides?

Toxicity, including ototoxicity and nephrotoxicity.

What are the common drugs classified as aminoglycosides?

Gentamicin, tobramycin, amikacin, neomycin, and streptomycin.

What is a key characteristic of tetracyclines?

They are broad-spectrum antibiotics that are bacteriostatic.

What conditions are tetracyclines commonly used to treat?

Rickettsial disease, chlamydial diseases, cholera, Lyme disease, and mycoplasma pneumonia.

What can impair the absorption of tetracyclines?

Food, particularly calcium and magnesium, as they chelate with the drug.

What is the primary use of macrolides?

They are used for mycoplasma infections, pneumonia, chlamydial infections, and more.

What are the two components of streptogramins?

Dalfopristin and quinupristin.

What is the mechanism of action of oxazolidinones?

They inhibit protein synthesis by interfering with translation.

What is chloramphenicol reserved for?

Life-threatening infections.

What serious side effect is associated with chloramphenicol?

Bone marrow depression and aplastic anemia.

What is a unique side effect of chloramphenicol in newborns?

Gray baby syndrome.

What type of infections is clindamycin used for?

Infections caused by anaerobes and as adjunct therapy for toxin-producing bacteria.