Antibacterials Overview

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Questions and Answers

What is a common adverse drug reaction associated with cephalosporin therapy?

Water retention

Severe hallucinations

Diarrhea (correct)

Nephrotoxicity

Which type of bacteria are aminoglycosides primarily effective against?

Viruses

Gram-negative bacilli (correct)

Fungi

Gram-positive cocci

How do fluoroquinolones exert their antibacterial effect?

By binding to RNA polymerase

By disrupting cell wall synthesis

By enhancing protein synthesis

By inhibiting bacterial DNA synthesis (correct)

Which of the following antibiotics is used in the treatment of external ocular infections?

Ciprofloxacin Signup and view all the answers

What is the mechanism of action of tetracyclines?

Inhibiting protein synthesis Signup and view all the answers

Which of the following antibiotics is used in the treatment of bacterial conjunctivitis?

Chloramphenicol Signup and view all the answers

Which drug name is associated with cephalosporins?

Cefalor Signup and view all the answers

What is a significant treatment option for trachoma?

Topical tetracyclines Signup and view all the answers

What is the primary reason aminoglycosides should be avoided during pregnancy?

They are known to have teratogenic effects. Signup and view all the answers

Which class of antibiotics is known for being bacteriostatic and competitive inhibitors in folate synthesis?

Sulfonamides Signup and view all the answers

Which type of cross resistance describes the relationship between neomycin and streptomycin?

One way cross resistance Signup and view all the answers

What is superinfection primarily caused by?

Destruction of normal bacterial flora due to antimicrobial agents. Signup and view all the answers

Which antibiotic class is characterized as bactericidal and disrupts the bacterial cell wall synthesis?

Cephalosporins Signup and view all the answers

Which of the following is NOT a potential causative organism for superinfections?

E. coli Signup and view all the answers

What is advised when treating infections caused by high pathogenicity microbes?

To initiate multiple drugs at the same time for thorough treatment. Signup and view all the answers

Which of the following is a common result of prolonged use of immunosuppressive therapy regarding infections?

Development of superinfections Signup and view all the answers

What is one mechanism by which antibacterials can increase cell membrane permeability?

By increasing the leakage of cell material. Signup and view all the answers

Which of the following antibacterials is primarily associated with renal and ototoxicity?

Aminoglycosides Signup and view all the answers

Resistance to a particular sulphonamide often indicates resistance to which of the following?

Other members of the sulphonamide group. Signup and view all the answers

Which mechanism involves the alteration of membrane permeability in the development of drug resistance?

Mutation. Signup and view all the answers

Which of the following is NOT a common toxicity associated with Vancomycin?

Bone marrow depression Signup and view all the answers

What kind of enzyme can a microbe develop to combat antimicrobial drugs?

Enzymes that degrade the antimicrobial molecule. Signup and view all the answers

Which of the following is a consequence of interfering with bacterial DNA function?

Altered mRNA code. Signup and view all the answers

What describes cross resistance in bacteria?

Resistance to drugs that are chemically similar. Signup and view all the answers

Study Notes

Antibacterials

Antibacterials act against bacteria.
Initially, antibacterials were derived from other microorganisms, known as antibiotics.
Currently, most antibacterials are synthesized from chemicals.
Antibacterial mechanisms of action include increasing cell membrane permeability, causing cell wall lysis, suppressing protein synthesis, interfering with DNA function, inhibiting DNA gyrase activity, confusing mRNA code and changing permeability, and interfering with bacterial metabolism.
Common toxicities associated with various antibacterials include bone marrow depression, renal and 8th cranial nerve damage, renal and ototoxicity, renal and neurological toxicity, hepatic and renal damage, bone marrow depression, neurological complications, and renal damage.
Drug resistance can occur through mutation, gene transfer through conjugation, transformation and transduction.
Resistance mechanisms include the generation of new metabolic pathways, development of new enzymes to break down antimicrobials, and alteration in membrane permeability.
Cross-resistance occurs when an organism resistant to one drug also exhibits resistance to structurally related drugs.
Therapeutic guidelines to combat drug resistance:
- Use multiple drugs for prolonged treatment, especially in cases like tuberculosis.
- Thorough eradication of highly pathogenic microbes is crucial.
- Avoid prolonged treatment for low pathogenicity microbes.

Antibiotic Use During Pregnancy

Aminoglycosides, chloramphenicol, tetracycline, fluoroquinolones, sulfonamides, and nitrofurantoin should be avoided during pregnancy due to teratogenic effects and potential adverse effects on fetomaternal well-being.

Superinfection

Superinfection is a new infection that develops during antimicrobial therapy due to the destruction of normal bacterial flora.
Normal flora serves by liberating bacitracin to inhibit pathogens and depriving pathogens of nutrients through competition.
Superinfection is more common in patients with AIDS, diabetes mellitus, bone marrow depression, prolonged immunosuppressive therapies, and corticosteroid usage.
Common causative organisms of superinfection:
- Staphylococcus
- Candida albicans
- Proteus group
- Pseudomonas group
- Clostridium difficile

Classes of Antibiotics

Sulfonamides, Cephalosporins, Aminoglycosides, Tetracyclines, Chloramphenicol, and Fluoroquinolones.

Sulfonamides

Synthetic bacteriostatic antibiotics that competitively inhibit the conversion of p-aminobenzoic acid to dihydrofolate, essential for bacterial folate synthesis.
Uses of sulfonamides include treatment of chlamydial infections, inclusion conjunctivitis, and toxoplasmosis.

Cephalosporins

Bactericidal β-lactam antibiotics that disrupt peptidoglycan synthesis in bacterial cell walls.
Derived from the fungus Acremonium.
Adverse Effects: diarrhea, nausea, rash, electrolyte imbalances, pain at injection site, vomiting, headache, dizziness, oral and vaginal candidiasis, pseudomembranous colitis, superinfection, eosinophilia, nephrotoxicity, neutropenia, thrombocytopenia, and fever.

Aminoglycosides

Bacterial protein synthesis inhibitors, mainly active against gram-negative bacilli.
Examples include gentamycin, tobramycin, and neomycin.

Fluoroquinolones

Quinolone antibiotics with a fluorine atom in their structure, effective against both Gram-negative and Gram-positive bacteria.
Example: ciprofloxacin.
Inhibit bacterial DNA synthesis by interfering with DNA gyrase and topoisomerase IV enzymes.
Used in the eye for corneal ulcers, superficial infections, and external ocular infections such as conjunctivitis and keratoconjunctivitis.

Tetracyclines & Chloramphenicol

Tetracyclines:
- Inhibit protein synthesis.
- Active against Gram-positive and Gram-negative bacteria, some fungi, and chlamydia.
- Used in bacterial blephritis, conjunctivitis, keratitis, and trachoma
- Examples: tetracycline hydrochloride, histazoline.
Chloramphenicol:
- Inhibit protein synthesis.
- Broad spectrum and bacteriostatic.
- Treats bacterial conjunctivitis.
- Examples: optachlor, mexchlor, chloroptic

Eye Conditions & Antibiotic Uses

Trachoma: Treated with topical and systemic tetracyclines, erythromycin, or systemic azithromycin

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Description

This quiz explores the mechanisms, uses, and toxicities of antibacterials, focusing on their action against bacteria. It highlights the synthesis of antibacterials, the evolution of drug resistance, and the various side effects associated with their use. Test your understanding of these crucial medications and their impact on health.