antimicrobial therapy Flashcards
What was the leading cause of death before the discovery of antibiotics?
Infectious diseases.
Is penicillin toxic to humans?
No, it is not toxic to humans.
How are antibiotics different from other drugs?
Antibiotics have activity in several body sites, are used by large numbers of patients for short periods, can be used both prophylactically and therapeutically, and their activity against microorganisms is rarely specific to a single organism.
What are the ideal characteristics of antibiotics?
Selective toxicity, slow emergence of resistance, non-toxic to the host, and no interference with other drugs.
Is it possible for antibiotics to possess all the ideal characteristics?
It is difficult for antibiotics to possess all the ideal characteristics simultaneously.
What does selective toxicity mean?
Selective toxicity refers to the ability of antibiotics to target and destroy harmful microorganisms while causing minimal harm to the host.
How can drug resistance affect the recipient of antibiotics?
Drug resistance can reduce the effectiveness of antibiotics in treating infections.
What are the differences between microorganisms and the host that contribute to selective toxicity and efficacy of antibiotics?
Differences in structure and metabolism between microorganisms (prokaryotes) and the host (eukaryotes) allow antibiotics to selectively target and affect the microorganisms while minimizing harm to the host.
What is the difference between Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, while Gram-negative bacteria have an additional outer membrane and a thinner peptidoglycan layer.
What are the principles considered in the selection of antibiotics?
Likely pathogens, pathogen susceptibility to specific agents, antimicrobial resistance patterns, pharmacokinetics of the selected agent, and patient factors are taken into account.
What are Gram-positive atypicals?
Gram-positive atypical bacteria do not conform to the typical Gram-positive characteristics but are susceptible to certain antibiotics effective against Gram-positive bacteria.
What are Gram-negative anaerobes?
Gram-negative anaerobes are bacteria that are both Gram-negative and capable of surviving and growing in the absence of oxygen.
What is the difference between broad-spectrum and narrow-spectrum antibiotics?
Broad-spectrum antibiotics are effective against a wide range of bacteria, including both Gram-positive and Gram-negative, while narrow-spectrum antibiotics target specific types or groups of bacteria.
What is the significance of empirical treatment in antibiotic therapy?
Empirical treatment involves initiating antibiotic therapy before the causative microorganism is identified, aiming to cover a broad range of likely pathogens until more specific information is available.
What are the potential risks associated with using broad-spectrum antibiotics?
Broad-spectrum antibiotics may increase the risk of resistance development and side effects compared to narrow-spectrum antibiotics.
What is meant by antimicrobial resistance patterns?
Antimicrobial resistance patterns refer to the susceptibility or resistance of specific pathogens to different antibiotics, which helps guide appropriate antibiotic selection.
What is pharmacokinetics in relation to antibiotic selection?
Pharmacokinetics refers to how the body absorbs, distributes, metabolizes, and eliminates the antibiotic, and it is considered when selecting the appropriate antibiotic for a particular infection.
What is the mechanism of action of beta-lactam antibiotics?
Beta-lactam antibiotics, such as penicillins, cephalosporins, carbapenems, and monobactams, bind to bacterial transpeptidases (penicillin-binding proteins) and inhibit cell wall formation, leading to cell lysis. They are bactericidal.
Name some examples of beta-lactam antibiotics.
Examples of beta-lactam antibiotics include benzylpenicillin, flucloxacillin, amoxicillin, cephalexin, cefuroxime, imipenem, meropenem, and aztreonam.
What is the functional unit of beta-lactam antibiotics?
The functional unit of beta-lactam antibiotics is the beta-lactam ring.
What is the mode of action of glycopeptides antibiotics?
Glycopeptides antibiotics, such as vancomycin, bind to the precursors of bacterial cell wall peptidoglycan and inhibit its synthesis, resulting in cell death. They are bactericidal.
Which antibiotics inhibit DNA replication?
Quinolones, such as ciprofloxacin and levofloxacin, inhibit bacterial DNA gyrase and topoisomerase IV, enzymes involved in DNA replication. This leads to DNA damage and cell death. They are bactericidal.
What is the mode of action of metronidazole?
Metronidazole enters bacterial cells and interacts with DNA, generating toxic metabolites that cause DNA strand breaks and cell death. It is bactericidal against anaerobic bacteria.
Which antibiotic inhibits RNA synthesis?
Rifampicin inhibits bacterial RNA polymerase, preventing the transcription of bacterial RNA. It is bactericidal.
Which antibiotics inhibit protein synthesis?
Macrolides (e.g., erythromycin), aminoglycosides (e.g., gentamicin), and tetracyclines (e.g., doxycycline) inhibit bacterial protein synthesis by targeting different components of the ribosome. They can be bacteriostatic or bactericidal, depending on the specific antibiotic and concentration.
What are antimetabolites antibiotics?
Antimetabolites, such as trimethoprim and sulphonamides (sulfonamides), interfere with the synthesis of essential metabolites needed for bacterial growth, such as nucleic acids and folic acid. They are bacteriostatic.
What is the difference between bacteriostatic and bactericidal antibiotics?
Bacteriostatic antibiotics inhibit the growth and replication of bacteria, while bactericidal antibiotics directly kill the bacteria.
What is the difference between narrow-spectrum and broad-spectrum antibiotics?
Narrow-spectrum antibiotics are effective against a limited range of bacteria, targeting specific types or groups. In contrast, broad-spectrum antibiotics are effective against many bacteria, including both Gram-positive and Gram-negative.
How do bacteria develop resistance against beta-lactam antibiotics?
Bacteria can produce beta-lactamases, enzymes that hydrolyze the beta-lactam ring of beta-lactam antibiotics, rendering them inactive.
How can resistance mediated by beta-lactamases be overcome?
Beta-lactamase inhibitors, such as clavulanic acid (and other similar compounds), can be used in combination with beta-lactam antibiotics to inhibit the action of beta-lactamases, restoring the effectiveness of the antibiotics.
What are some examples of penicillins?
Examples of penicillins include penicillin G (benzylpenicillin), penicillin V (phenoxymethylpenicillin), amoxicillin, ampicillin, flucloxacillin, temocillin, meticillin (not used clinically), ticarcillin, and piperacillin.
What is the difference between natural and chemically modified penicillins?
Natural penicillins, such as penicillin G, have poor oral absorption. Chemically modified penicillins, such as penicillin V, amoxicillin, and ampicillin, have better oral absorption. Chemically modified penicillins also have broader spectrums and longer half-lives.
Which penicillins are resistant to beta-lactamases?
Flucloxacillin, temocillin, and meticillin (not used clinically) are penicillins resistant to beta-lactamase action.
What are extended-spectrum penicillins?
Extended-spectrum penicillins, such as ticarcillin and piperacillin, have activity against a broader range of bacteria, including Pseudomonas species.
What is an important consideration for all beta-lactams?
Allergy is an important consideration when prescribing beta-lactam antibiotics.
Where can you expect to learn more about these antibiotics?
You will learn more about these antibiotics during system-based modules and clinical placements.
What is the combination of amoxicillin and clavulanic acid used for?
Amoxicillin and clavulanic acid are often combined to enhance the effectiveness of amoxicillin against beta-lactamase-producing bacteria. Clavulanic acid inhibits the action of beta-lactamases, allowing amoxicillin to remain active.
What is the spectrum of activity for first-generation cephalosporins?
First-generation cephalosporins, such as cefadroxil and cefazolin, are active against Gram-positive bacteria but have limited activity against Gram-negative bacteria. They are not active against Haemophilus influenzae.
What is the spectrum of activity for second-generation cephalosporins?
Second-generation cephalosporins, such as cefuroxime and cefoxitin, have slightly decreased activity against Gram-positive bacteria but increased activity against Gram-negative bacteria. They are active against Haemophilus influenzae.
What is the spectrum of activity for third-generation cephalosporins?
Third-generation cephalosporins, such as ceftazidime and ceftriaxone, have decreased activity against Gram-positive bacteria but increased activity against Gram-negative bacteria. They also have antipseudomonal activity. They exhibit increased resistance to beta-lactamases.
