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Foundations of health and disease > antimicrobial therapy > Flashcards

antimicrobial therapy Flashcards

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1
Q

What was the leading cause of death before the discovery of antibiotics?

A

Infectious diseases.

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2
Q

Is penicillin toxic to humans?

A

No, it is not toxic to humans.

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3
Q

How are antibiotics different from other drugs?

A

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.

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4
Q

What are the ideal characteristics of antibiotics?

A

Selective toxicity, slow emergence of resistance, non-toxic to the host, and no interference with other drugs.

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5
Q

Is it possible for antibiotics to possess all the ideal characteristics?

A

It is difficult for antibiotics to possess all the ideal characteristics simultaneously.

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6
Q

What does selective toxicity mean?

A

Selective toxicity refers to the ability of antibiotics to target and destroy harmful microorganisms while causing minimal harm to the host.

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7
Q

How can drug resistance affect the recipient of antibiotics?

A

Drug resistance can reduce the effectiveness of antibiotics in treating infections.

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8
Q

What are the differences between microorganisms and the host that contribute to selective toxicity and efficacy of antibiotics?

A

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.

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9
Q

What is the difference between Gram-positive and Gram-negative bacteria?

A

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.

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10
Q

What are the principles considered in the selection of antibiotics?

A

Likely pathogens, pathogen susceptibility to specific agents, antimicrobial resistance patterns, pharmacokinetics of the selected agent, and patient factors are taken into account.

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11
Q

What are Gram-positive atypicals?

A

Gram-positive atypical bacteria do not conform to the typical Gram-positive characteristics but are susceptible to certain antibiotics effective against Gram-positive bacteria.

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12
Q

What are Gram-negative anaerobes?

A

Gram-negative anaerobes are bacteria that are both Gram-negative and capable of surviving and growing in the absence of oxygen.

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13
Q

What is the difference between broad-spectrum and narrow-spectrum antibiotics?

A

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.

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14
Q

What is the significance of empirical treatment in antibiotic therapy?

A

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.

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15
Q

What are the potential risks associated with using broad-spectrum antibiotics?

A

Broad-spectrum antibiotics may increase the risk of resistance development and side effects compared to narrow-spectrum antibiotics.

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16
Q

What is meant by antimicrobial resistance patterns?

A

Antimicrobial resistance patterns refer to the susceptibility or resistance of specific pathogens to different antibiotics, which helps guide appropriate antibiotic selection.

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17
Q

What is pharmacokinetics in relation to antibiotic selection?

A

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.

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18
Q

What is the mechanism of action of beta-lactam antibiotics?

A

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.

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19
Q

Name some examples of beta-lactam antibiotics.

A

Examples of beta-lactam antibiotics include benzylpenicillin, flucloxacillin, amoxicillin, cephalexin, cefuroxime, imipenem, meropenem, and aztreonam.

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20
Q

What is the functional unit of beta-lactam antibiotics?

A

The functional unit of beta-lactam antibiotics is the beta-lactam ring.

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21
Q

What is the mode of action of glycopeptides antibiotics?

A

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.

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22
Q

Which antibiotics inhibit DNA replication?

A

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.

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23
Q

What is the mode of action of metronidazole?

A

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.

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24
Q

Which antibiotic inhibits RNA synthesis?

A

Rifampicin inhibits bacterial RNA polymerase, preventing the transcription of bacterial RNA. It is bactericidal.

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25
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.
26
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.
27
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.
28
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.
29
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.
30
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.
31
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.
32
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.
33
Which penicillins are resistant to beta-lactamases?
Flucloxacillin, temocillin, and meticillin (not used clinically) are penicillins resistant to beta-lactamase action.
34
What are extended-spectrum penicillins?
Extended-spectrum penicillins, such as ticarcillin and piperacillin, have activity against a broader range of bacteria, including Pseudomonas species.
35
What is an important consideration for all beta-lactams?
Allergy is an important consideration when prescribing beta-lactam antibiotics.
36
Where can you expect to learn more about these antibiotics?
You will learn more about these antibiotics during system-based modules and clinical placements.
37
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.
38
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.
39
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.
40
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.
41
What is the spectrum of activity for fourth-generation cephalosporins?
Fourth-generation cephalosporins, such as cefepime, exhibit broad-spectrum activity against both Gram-positive and Gram-negative bacteria. They have increased resistance to beta-lactamases.
42
What is the spectrum of activity for fifth-generation cephalosporins?
Fifth-generation cephalosporins, such as ceftaroline, have broad-spectrum activity against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). They also exhibit increased resistance to beta-lactamases.
43
What does MRSA stand for?
MRSA stands for methicillin-resistant Staphylococcus aureus.
44
What are examples of glycopeptide antibiotics?
Examples of glycopeptide antibiotics include vancomycin, teicoplanin, and telavancin. They are primarily active against Gram-positive bacteria.
45
When are glycopeptide antibiotics, such as vancomycin, typically used?
Glycopeptide antibiotics are used intravenously for serious infections caused by Gram-positive organisms that produce beta-lactamases or do not respond to other treatments.
46
What is the oral use of vancomycin for?
Although not well absorbed orally, Vancomycin is used to treat Clostridium difficile infections associated with diarrhea.
47
What is an important consideration regarding the use of vancomycin?
Nephrotoxicity (renal toxicity) is an important adverse effect associated with the use of vancomycin.
48
What is the core drug within the glycopeptide class?
The core drug within the glycopeptide class is vancomycin.
49
What is the mechanism of action of vancomycin?
Vancomycin inhibits bacterial cell wall formation (peptidoglycans) through a different target compared to beta-lactam antibiotics.
50
What is the GI absorption of vancomycin?
The gastrointestinal (GI) absorption of vancomycin is very low.
51
How is vancomycin primarily eliminated from the body?
Vancomycin is primarily eliminated through the urine.
52
What are some adverse effects associated with vancomycin?
Vancomycin can cause nephrotoxicity (toxicity to the kidneys) and ototoxicity (toxicity to organs or nerves involved in hearing or balance).
53
What is the activity spectrum of vancomycin?
Vancomycin is active against Gram-positive bacteria but has no activity against Gram-negative bacteria. It is effective against many resistant strains, including methicillin-resistant Staphylococcus aureus (MRSA).
54
How do bacteria synthesize proteins?
Bacteria synthesise proteins using ribosomes, which are complex molecular structures involved in protein translation. Ribosomes read the genetic code in mRNA and assemble amino acids into proteins.
55
What is meant by selective toxicity?
Selective toxicity refers to the ability of a drug to specifically target and inhibit or kill microbial pathogens while causing minimal harm to the host.
56
What is the difference between 70S and 80S ribosomes?
Bacteria have 70S ribosomes, consisting of a 50S subunit and a 30S subunit, while eukaryotic cells, including human cells, have larger 80S ribosomes.
57
What are macrolides and their activity?
Macrolides, such as erythromycin, clarithromycin, and azithromycin, can have both bacteriostatic (inhibit bacterial growth) or bactericidal (kill bacteria) effects. They exhibit activity against Gram-positive bacteria, Gram-negative bacteria, and cell wall-deficient bacteria.
58
When are macrolides prescribed instead of penicillins?
Macrolides can be prescribed as an alternative to penicillins in cases of allergy or resistance to penicillins. They have a similar broad spectrum of activity to penicillins.
59
What is the core drug within the macrolide class?
The core drug within the macrolide class is clarithromycin.
60
What is the oral bioavailability of clarithromycin?
Clarithromycin has good oral bioavailability, meaning it is well-absorbed when taken orally.
61
What is the protein binding characteristic of clarithromycin?
Clarithromycin has high protein binding, affecting its distribution and metabolism within the body.
62
How is clarithromycin metabolized?
Clarithromycin is primarily metabolized in the liver.
63
What is the half-life of clarithromycin?
The half-life of clarithromycin ranges from 1 to 6 hours.
64
How is clarithromycin excreted from the body?
Clarithromycin is excreted as metabolites in the bile.
65
What is Gram-negative Clarithromycin?
Clarithromycin inhibits protein synthesis in bacterial ribosomes by binding to the 50S subunit.
66
What are some adverse effects associated with clarithromycin?
Adverse effects of clarithromycin may include nausea and diarrhea. It may also have the potential to alter cardiac conduction, leading to arrhythmias.
67
What is the activity spectrum of clarithromycin?
Clarithromycin has a broad spectrum of activity, similar to amoxicillin. It is effective against Streptococcus pyogenes (causing sore throat, skin infections), pneumococcal infections (respiratory tract), coliform infections (urinary tract infections), and cell wall-deficient bacteria such as Chlamydia.
68
What are some examples of aminoglycoside antibiotics?
Examples of aminoglycoside antibiotics include gentamicin. They are bactericidal, meaning they kill bacteria.
69
What are some potential adverse effects of aminoglycosides?
Aminoglycosides can be nephrotoxic (toxic to the kidneys) and ototoxic (toxic to organs or nerves involved in hearing or balance).
70
What are some characteristics of tetracycline antibiotics?
Tetracycline antibiotics, such as doxycycline and minocycline, are bacteriostatic, meaning they inhibit bacterial growth. They have a broad spectrum of activity.
71
What are some potential adverse effects of tetracyclines?
Tetracyclines can cause phototoxicity (toxic effect triggered by exposure to light) and can chelate (bind) to metal ions, leading to interactions or disruptions in the body.
72
What are some examples of quinolone antibiotics?
Examples of quinolone antibiotics include ciprofloxacin, nalidixic acid, norfloxacin, and ofloxacin.
73
What is the mechanism of action of quinolones?
Quinolones inhibit the enzymes known as DNA gyrases, which are essential for supercoiling, replication, and separation of circular bacterial DNA. By inhibiting these enzymes, quinolones lead to rapid bacterial cell death.
74
What is the spectrum of activity for quinolones?
Quinolones have a broad spectrum of activity, including Gram-negative bacteria, Gram-positive bacteria, anaerobes, Mycoplasma, and Chlamydia, depending on the specific quinolone.
75
What are some common uses of quinolones?
Quinolones treat urinary tract infections (although not considered first-line), pseudomonal infections, gastrointestinal infections, prostatitis, and sexually transmitted infections.
76
What is the mode of action of metronidazole?
Metronidazole is a prodrug that is metabolized by anaerobic organisms into its active form. The metabolites produced are toxic to DNA, leading to bacterial cell death. Metronidazole is bactericidal.
77
What are some considerations regarding metronidazole?
Metronidazole is considered potentially mutagenic, carcinogenic, and teratogenic, meaning it may have the potential to induce mutations, increase the risk of cancer, and cause congenital disabilities.
78
What is the mode of action of rifampicin?
Rifampicin is bactericidal and primarily used to treat Mycobacterial infections (such as Mycobacterium tuberculosis and Mycobacterium leprae). It binds to RNA polymerase and inhibits mRNA synthesis.
79
What are some important considerations when using rifampicin?
Rifampicin can cause metabolic interactions due to its strong induction of cytochrome P450 enzymes. It can also cause an orange colouration of saliva, tears, and sweat. Additionally, it can potentially be mutagenic, meaning it can increase the mutation rate.
80
What is co-trimoxazole?
Co-trimoxazole combines sulfonamide and trimethoprim antibiotics that synergistically inhibit bacterial growth.
81
What is the mode of action of co-trimoxazole?
Sulfonamides and trimethoprim in co-trimoxazole act in the same pathway but at different stages, specifically in synthesising tetrahydrofolate. They interfere with the production of tetrahydrofolate necessary for bacterial growth.
82
What is the significance of PABA (para-aminobenzoic acid) in relation to sulfonamides?
Sulfonamides are structurally similar to PABA and competitively inhibit the enzyme responsible for incorporating PABA into the folate pathway. This disrupts the synthesis of nucleic acids and proteins in bacteria.
83
Are sulfonamides and trimethoprim bacteriostatic or bactericidal?
Sulfonamides and trimethoprim are generally considered bacteriostatic, inhibiting bacterial growth rather than directly killing bacteria.
84
Is co-trimoxazole bactericidal or bacteriostatic?
Co-trimoxazole may have bactericidal activity, meaning it can directly kill bacteria, although it is primarily considered a synergistic bacteriostatic combination. Resistance to co-trimoxazole is not common.
85
What is the definition of antimetabolites?
Antimetabolites are drugs that are chemically similar to naturally occurring metabolites but differ enough to interfere with normal metabolic pathways, disrupting the synthesis of essential molecules in bacteria.
86
What does synergistic association mean?
Synergistic association refers to the interaction or cooperation of two or more organisations, substances, or agents that produce a combined effect greater than the sum of their separate effects.
87
What are some resistance mechanisms that bacteria can develop against antibiotics?
Bacteria can develop resistance through various mechanisms, including: Inactivation or modification of the antibiotic Alteration of microbial enzymes that transform pro-drugs into the active form Alteration of the target site where the antibiotic binds Reduced uptake of the antibiotic into the bacterial cell Enhanced export of the antibiotic through efflux pumps Development of alternative metabolic pathways
88
How does inactivation or modification of the antibiotic contribute to resistance?
Bacteria may produce enzymes that can chemically modify or inactivate the antibiotic, rendering it ineffective against the bacteria.
89
What does the alteration of microbial enzymes refer to in terms of resistance?
Bacteria can undergo genetic mutations that lead to enzyme changes, preventing the conversion of pro-drugs (inactive forms) into active moieties that effectively target the bacteria.
90
How does the alteration of the target site contribute to resistance?
Genetic changes in bacteria can alter the structure or function of the target site where the antibiotic typically binds. This alteration can prevent the antibiotic from effectively interacting with its target, reducing its efficacy.
91
How does reducing the uptake of the antibiotic affect resistance?
Bacteria can develop mechanisms to decrease the uptake of antibiotics into their cells, reducing the amount of drug available to exert its antimicrobial effect.
92
What is the role of efflux pumps in antibiotic resistance?
Efflux pumps are specialised transport proteins in bacteria that can actively pump out antibiotics from the bacterial cell, effectively removing the drug and reducing its concentration within the cell.
93
How can the development of alternative metabolic pathways contribute to resistance?
Bacteria may develop alternative metabolic pathways that bypass the targeted pathway affected by the antibiotic. This allows them to continue vital cellular processes even in the presence of the drug.
94
Do antibiotics directly cause resistance?
Antibiotics themselves do not cause resistance; instead, they can affect the rate of spread of resistance by exerting selective pressure on bacteria, favouring the survival and growth of resistant strains.
95
What are some examples of problematic antibiotic-resistant bacteria?
Examples of problematic antibiotic-resistant bacteria include Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), Extended Spectrum β-lactamase-producing organisms (ESBL/AMPC), and tuberculosis (TB), as well as Acinetobacter species.
96
What are some strategies to fight the spread of antibiotic resistance?
Strategies to combat the spread of antibiotic resistance include: Preventing infections from occurring in the first place and implementing measures to prevent the spread of resistant bacteria. Tracking and monitoring the presence of resistant bacteria to understand their prevalence and distribution. Improving the use of antibiotics through appropriate prescribing practices, promoting antimicrobial stewardship, and avoiding unnecessary or excessive antibiotic use. Promoting the development of new antibiotics and diagnostic tests for detecting and identifying resistant bacteria.
97
How can infections be prevented and the spread of resistant bacteria be controlled?
Infections can be prevented through proper hand hygiene, infection control measures in healthcare settings, immunisations, and antimicrobial prophylaxis. Controlling the spread of resistant bacteria involves implementing isolation precautions, surveillance for resistant strains, and educating healthcare providers and the general public about infection prevention and appropriate antibiotic use.
98
What is the importance of tracking resistant bacteria?
Tracking resistant bacteria allows for monitoring their prevalence, spread, and resistance patterns. This information helps guide infection control measures, identify areas with high resistance rates, and develop targeted interventions to limit the spread of resistant strains.
99
How can the use of antibiotics be improved?
The use of antibiotics can be improved by adhering to appropriate prescribing practices, avoiding unnecessary or excessive antibiotic use, ensuring proper dosing and duration of treatment, and promoting antimicrobial stewardship programs that aim to optimise antibiotic use, minimise resistance, and improve patient outcomes.
100
What is the significance of promoting the development of new antibiotics and diagnostic tests?
Promoting the development of new antibiotics and diagnostic tests is crucial to combat antibiotic resistance. The discovery of new antibiotics helps expand the treatment options for resistant infections. At the same time, improved diagnostic tests aid in rapidly and accurately identifying resistant bacteria, enabling targeted therapy and effective infection control measures.
101
What is the role of NICE guidance in addressing antibiotic resistance?
NICE (National Institute for Health and Care Excellence) provides evidence-based guidelines and recommendations to healthcare professionals, aiming to optimise the use of antibiotics and address the challenges of antibiotic resistance. Following NICE guidance helps ensure appropriate management of antibiotic use and supports the implementation of effective strategies to combat resistance.

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