Pharmacology for Nursing Care: Antimicrobials

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Questions and Answers

What is a notable advantage of combining bacteriostatic drugs?

They only target gram-positive bacteria.

They have no side effects.

They produce a bactericidal action. (correct)

They significantly increase the MIC of each component.

Which of the following is NOT a toxicity related to sulfonamides?

Renal damage due to crystal deposition

Kernicterus in neonates

Megaloblastic anemia (correct)

Photosensitivity

What is a reason for the continued use of sulfonamides even after many years?

They have a wide antibacterial spectrum.

They are cheap and easy to administer orally. (correct)

They can be used as single agents for all infections.

They are expensive and complex to administer.

What is a possible outcome of combining trimethoprim and sulfonamides?

Delayed development of bacterial resistance. Signup and view all the answers

In which population is kernicterus most likely to occur due to sulfonamide treatment?

Premature infants Signup and view all the answers

What is Imipenem commonly used with to increase its effectiveness?

Cilastatin Signup and view all the answers

Which side effect is more likely with Imipenem compared to Meropenem?

Increased bleeding tendency Signup and view all the answers

What is a unique characteristic of Aztreonam?

Relatively resistant to beta-lactamase Signup and view all the answers

What is the primary use of Vancomycin?

Bactericidal agent for MRSA and MRSE Signup and view all the answers

What form of Vancomycin is used to treat C.difficile colitis?

PO form Signup and view all the answers

What is the primary mechanism by which sulfanilamide exerts its effects?

Competitive inhibition of dihydropteroate synthase Signup and view all the answers

Which statement correctly describes the selectivity between microbes and humans regarding precursor synthesis?

Microbes can synthesize precursors to dihydrofolic acid, while humans cannot Signup and view all the answers

What is a shared characteristic between the dihydrofolate reductase in humans and microbes?

Both can reduce dihydrofolic acid Signup and view all the answers

What is the role of trimethoprim in the combination therapy with sulfamethoxazole?

It specifically inhibits the microbial dihydrofolate reductase Signup and view all the answers

Which compound is directly inhibited by sulfanilamide in the presence of PABA?

Dihydropteroate Signup and view all the answers

What is the result of the synergistic effect in the combination of trimethoprim and sulfamethoxazole?

They inhibit separate pathways in folate synthesis Signup and view all the answers

Why are humans not affected by sulfanilamide in the same way as microbes?

Humans have a different structural enzyme than microbes Signup and view all the answers

Which of the following correctly illustrates the difference in folic acid permeability between humans and microbes?

Microbes are impermeable to folic acid unlike humans Signup and view all the answers

Which of the following drugs is not effective against beta-lactamase producing bacteria?

Ampicillin Signup and view all the answers

What is a common non-allergic adverse effect of penicillin?

Gastrointestinal symptoms Signup and view all the answers

Which cephalosporin class adverse effect can occur when taken with alcohol?

Liver toxicity Signup and view all the answers

Imipenem is effective against which of the following?

Gram-positive, Gram-negative, and anaerobes Signup and view all the answers

Which of these antibiotics is known for its role against Methicillin Resistant Staphylococcus aureus (MRSA)?

Oxacillin Signup and view all the answers

What is the primary reason the administration of Ticarcillin could be associated with sodium overload?

It contains a high sodium salt. Signup and view all the answers

Which combination acts as a beta-lactamase inhibitor?

Ampicillin and sulbactam Signup and view all the answers

What distinguishes Ticarcillin from Carbenicillin?

Ticarcillin is more potent against pseudomonas. Signup and view all the answers

What classification of antimicrobials describes their ability to target specific types of bacteria?

Spectrum of activity Signup and view all the answers

Which type of antimicrobial is known to inhibit bacterial growth without killing the bacteria?

Bacteriostatic Signup and view all the answers

Which bacterial type is likely to be targeted by a bactericidal antimicrobial?

Staphylococcus aureus Signup and view all the answers

Which class of antibiotics is often produced naturally and derived from fungi or bacteria?

Natural Signup and view all the answers

What characteristic distinguishes bacteriostatic antimicrobials from bactericidal ones?

They inhibit growth without killing. Signup and view all the answers

Which mechanism of action is involved in the selective inhibition of bacterial targets by antimicrobials?

Disruption of cell wall synthesis Signup and view all the answers

In which of the following conditions would a broad-spectrum antimicrobial be most appropriately used?

When the specific pathogen is unknown Signup and view all the answers

Which classification of antimicrobials encompasses those that are developed wholly through chemical synthesis?

Synthetic Signup and view all the answers

Study Notes

Antimicrobials Overview

Antimicrobials are categorized by chemical structure, source (natural, synthetic, semisynthetic), spectrum of activity (narrow vs. broad), antimicrobial activity (bacteriostatic vs. bactericidal), kinetic properties (oral/systemic), and mechanism of action.
Classification includes Gram-positive and Gram-negative bacteria, distinguished by the Gram staining method developed by Hans Christian Gram in 1884.

Bacterial Pathogens

Streptococcus pneumoniae: causes pneumonia.
Escherichia coli: responsible for urinary tract infections (UTIs).
Group A Streptococcus: associated with tonsillitis and pharyngitis.
Neisseria gonorrhea: a causative agent of sexually transmitted diseases (STDs).
Pseudomonas aeruginosa: common in hospital settings.
Mycoplasma pneumonia: also leads to pneumonia, lacks a cell wall.
Chlamydia trachomatis: associated with STDs.

Mechanism of Action

Sulfanilamide acts as a competitive inhibitor of dihydropteroate synthase, mimicking p-aminobenzoic acid (PABA).
Selective inhibition occurs because microbes synthesize precursors to dihydrofolic acid, which humans do not.
Trimethoprim inhibits microbial dihydrofolate reductase, distinguishing it from human enzymes.
Co-trimoxazole (Trimethoprim + Sulfamethoxazole) shows a synergistic bactericidal effect when used together.

Clinical Use of Sulfonamides

Sulfonamides are used for the treatment and prevention of UTIs due to gram-negative bacteria.
Side effects include photosensitivity, hemolytic anemia, renal damage due to crystal deposition, and potential kernicterus in neonates.
Trimethoprim is well-tolerated but can cause rash, nausea, and folate deficiency complications in susceptible populations.

Penicillin Types and Effects

Extended Spectrum Aminopenicillins (e.g., Ampicillin, Amoxicillin) cover some gram-negative bacteria, with Amoxicillin having better bioavailability.
Penicillinase-resistant penicillins (e.g., Oxacillin, Nafcillin) are effective against beta-lactamase producing organisms.
Adverse effects of penicillins include allergic reactions, gastrointestinal symptoms, and potential seizures.

Cephalosporins

Broad-spectrum antibiotics with potential adverse effects including diarrhea, nephrotoxicity, and allergic reactions.
Some cephalosporins may cause liver toxicity if taken with alcohol, and can impact pregnancy outcomes.

Carbapenems

Imipenem has a broad spectrum and is resistant to most beta-lactamases but can cause seizures and increase bleeding tendency.
Meropenem has a lower seizure risk compared to Imipenem.
Aztreonam is effective against gram-negative infections and has no cross-reactivity with penicillins, making it well tolerated.

Vancomycin

Vancomycin is a last-resort treatment for methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE).
It is also used for oral treatment of Clostridium difficile colitis.
No absorption occurs with oral Vancomycin, making it effective only for gastrointestinal infections when delivered orally.

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Description

Test your knowledge on antimicrobials as discussed in 'Pharmacology for Nursing Care' by Lehne. This quiz covers essential bacterial classifications, including the differences between gram-positive and gram-negative bacteria. Learn about historical figures like Hans Christian Gram and their contributions to microbiology.