Antibiotic Therapy

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which route of administration is most commonly used for antibiotics?

Subcutaneous
Intravenous (IV)
Intramuscular (IM)
Oral (correct)

How long does it take for antibiotics to reach peak serum levels when given intravenously?

2 hours
15 minutes (correct)
30 minutes
1 hour

Where are antibiotics that are absorbed excreted from the body?

Liver only
Urine only
Urine or liver and biliary tract (correct)
Biliary tract only

How long do oral antibiotics take to reach peak serum levels?

1 hour Signup and view all the answers

When administered orally, much of the antibiotic is not absorbed and excreted in faeces.

True (A) Signup and view all the answers

What are the antibiotic targets in pathogens?

Cell wall, ribosomes, DNA replication, DNA gyrases, Metabolic pathways, Cell. membrane function Signup and view all the answers

How do antibiotics act on the bacterial cell wall?

Inhibit cell wall synthesis by preventing cross linking of peptidoglycan - bactericidal Signup and view all the answers

What are the positive characteristics of the antibiotic Penicillin?

<ul> <li>β lactam</li> <li>Very few side effects</li> <li>Range from narrow to broad spectrum</li> <li>Excreted (rapidly) via kidneys</li> <li>Safe in pregnancy</li> </ul> Signup and view all the answers

What are the limitations of the antibiotic Penicillin?

-Patients can be hypersensitive (allergic). -Rapid excretion via the kidneys. This results in frequent dosing -Resistance- Due to a long history of clinical use, many microbes have been exposed to these compounds and some resistant strains have been selected for. Signup and view all the answers

What are three principle Penicillin compounds?

<ol> <li>Benzylpenicillin- penicillin G, intravenous IV</li> <li>Phenoxymethyl penicillin- penicillin V, oral</li> <li>Benzathine penicillin- long acting, intramuscular (IM)</li> </ol> Signup and view all the answers

What are the characteristics of Penicillin V in terms of:-

Gram stain bacteria spectrum

Absorption

Sensitivity to stomach acid

Peak Plasma concentration time

Binding to plasma protein

how long serum levels are maintained for

Penicillin V is effective on a narrow range of largely Gram +ve bacteria. Absorbed through intestine Sensitive to stomach acid (30 mins before meal or 3 hours after) Peak plasma concentration 30-60 minutes after taking 75-90% binds to plasma proteins Serum levels maintained for 30-60 minutes Signup and view all the answers

What are the characteristics of Amoxicillin?

Amoxicillin is administered via IV or orally. It is a safe, well tolerated antibiotic. It is well-absorbed when given orally. It has a low binding ability to plasma proteins (longer half life) and good tissue distribution. Its effectiveness is challenged by spread of beta-lactamases. Signup and view all the answers

What are the characteristics of Amoxycillin with regards to:

Gram stain spectrum efficacy

Absorption

Sensivity to stomach acid

Peak plasma concentration

Tissue distribution

Plasma protein binding

Plasma half life

Amoxycillin has a broad spectrum effect across Gram +ve and Gram -ve bacteria. Absorbed through the intestine Stable in the presence of stomach acid Peak plasma concentration 60-120 minutes after taking Wide tissue distribution and it also has the capacity to enter the CSF (cerebrospinal fluid) if meninges are inflamed. 20% binds to plasma proteins Plasma half life is 60 minutes Signup and view all the answers

What are the various characteristics of antibiotics?

<ol> <li>Inhibitory/ bactericidal</li> <li>Time Dependant action (peak plasma concentration)</li> <li>Spectrum (Gram +ve or -ve)/ Anaerobic bacteria</li> <li>Absorption- Peritoneal versus IV, where it gets absorbed, acid sensitivity</li> <li>Distribution- Plasma binding proteins, GI/urinary tract, environment permissive for activity 6)Elimination via liver or kidney</li> </ol> Signup and view all the answers

What is the ideal antibiotic?

Kills bacteria, selective toxicity, good tissue distribution, long half life, peritoneal absorption, no significant drug interactions. Signup and view all the answers

What are the characteristics of the antibiotic Cephalosporin?

Cephalosporins inhibit cell wall synthesis and are bactericidal. Modified beta-lactam It has a longer half life in plasma Excreted via kidneys and urine Has a few side effects, reduced allergy Safe in pregnancy Narrow Gram -ve to broad (3rd) and extended spectrum (4th) Relatively resistant to beta lactamases Signup and view all the answers

What is the general usage of Cephalosporins in hospitals in Tayside and elsewhere?

Cephalosporins are broad spectrum antibiotics, which significantly affect the normal bowel flora. They kill the normal gut bacteria and allow the overgrowth of C. difficile which causes bad gastroenteritis. Their use in Tayside is very restricted. Signup and view all the answers

What are the characteristics of the antibiotic Glycopeptide?

1)They are not Beta lactic antibiotics. 2)Bactericidal 3)Excreted via the kidneys and urine; toxic levels of vancomycin in the blood can build up in patients who have kidney failure- causes red man syndrome 4) Limited to bacteria with Gram positive cell wall 5) Oral vancomycin can target Gram +ve GI microbes as it builds up in intestines. It doesn't get absorbed too easily and therefore is effective against C. difficile. 6) It has no activity against Gram -ve organisms. Signup and view all the answers

How do protein synthesis inhibitors work in antibiotics?

Antibiotics that inhibit protein synthesis do so by attaching to bacterial ribosomes, which are structurally different from mammalian ribosomes. Signup and view all the answers

In which situations can antibiotics be bacteriostatic and bactericidal w.r.t protein synthesis inhibitors?

Usually, protein synthesis can resume when the antibiotic is removed so most of these antibiotics (macrolides, tetracycline) are bacteriostatic. However, in aminoglycosides, the binding of these antibiotics to the ribosomes is lethal. This is what makes it bactericidal. Signup and view all the answers

What are the three main types of protein synthesis inhibitors? Give examples of each.

<ol> <li>Aminoglycosides e.g. Gentamicin</li> <li>Tetracyclines e.g. Doxycycline/Minocycline</li> <li>Macrolides e.g. Erythromycin</li> </ol> Signup and view all the answers

What are the characteristics of aminoglycosides (gentamicin)?

Aminoglycosides are protein synthesis inhibitors which are not absorbed from the gut and therefore must be given in IV. <ol> <li>Binds irreversibly to ribosomes inhibiting protein synthesis and thus it is bactericidal.</li> <li>Active mostly against Gram -ve aerobic bacteria. (coliform and Pseudomonas aeruginosa). It is effective in hospital for treating life threatening gram -ve infection.</li> <li>Excreted in urine</li> <li>Excessive levels in the serum would cause damage to kidney and the 8th cranial nerve- need to monitor blood levels of aminoglycosides.</li> </ol> Signup and view all the answers

What are the characteristics of Tetracycline antibiotics?

Tetracyclines are protein synthesis inhibitors that are bacteriostatic in nature. <ol> <li>Broad spectrum- useful against intracellular bacteria and atypical bacteria like chlamydia</li> <li>Resistance- increasing as more is being used</li> <li>Adverse effects- Destruction of normal intestinal flora resulting in increased secondary infections. Staining and impairment of the structure of bone and teeth, restricted use in infants, children and pregnancy.</li> </ol> Signup and view all the answers

What is the mode of action of tetracyclines?

Tetracyclines are actively transported into the cell. It binds to 30S subunit and prevents attachment of tRNA to acceptor sites. It stops the chain elongation. Doxycycline and Minocycline provide more efficient absorption- lower concentrations in gut, less disturbance, higher concentration in serum. Signup and view all the answers

What are the characteristics of Macrolides as an antibiotic?

Macrolides are <ol> <li>bacteriostatic</li> <li>commonly prescribed for Penicillin allergy and intracellular pathogens.</li> <li>This group of antibiotics is excreted via the liver, biliary tract and into the gut. They are not excreted in the urine.</li> <li>Lipophilic antibiotics pass through cell membranes easily.</li> <li>Useful in treating infections where intracellular bacteria hide from host's immune system 6)Safe in pregnancy</li> </ol> Signup and view all the answers

What are some types of Macrolides antibiotics?

Erythromycin, Clarythromycin (Gram -ve) and Azithromycin (Gram +ve) Signup and view all the answers

What is the mode of action of Macrolides antibiotics?

It binds to the 50S subunit and blocks translocation- therefore no release of peptides. Signup and view all the answers

What are the types of antibiotics that target nucleic acids in the pathogen?

Fluoroquinolones (for Gram -ve and Gram +ve) Metronidazole (for Anaerobes and protozoa) Trimethoprim (for primary use in urinary tract infection) Signup and view all the answers

What are the characteristics of Fluoroquinolones?

<ol> <li>Bactericidal</li> <li>Good intracellular activity</li> <li>Activity on infection of bones, UTIs, community acquired pneumonia</li> <li>Effective on gram -ve bacteria mostly</li> </ol> Signup and view all the answers

What is the mode of action of Fluoroquinolones?

Binds to the A subunit of DNA gyros (topoisomerase) and prevent supercoiling of DNA. It directly inhibits DNA synthesis. Signup and view all the answers

What is the usage status of Fluoroquinolones in clinical settings?

Use of broad spectrum antibiotics is now severely restricted to reduce the risk of C. difficile GI infection, especially in elderly patients. Signup and view all the answers

What are the types of Fluoroquinolones antibiotics?

Ciprofloxacin, moxiflocin, levofloxacin Signup and view all the answers

What are the characteristics of Metronidazole antibiotics?

1)It has good activity against anaerobe bacteria and parasites/ protozoa. 2) Administered via Oral or IV methods 3) Resistance is rare 4) Adverse reactions with alcohol- furred tongue etc. Signup and view all the answers

What is the mode of action of Metronidazole?

The drug is activated by reduction in strict anaerobes and it forms a toxic intermediate that induced DNA strand breakage. Signup and view all the answers

What are the characteristics of Trimethoprim antibiotics?

<ol> <li>Active against some Gram -ve and Gram -ve bacteria</li> <li>Common for acute UTI e.g. E. coli</li> <li>Excreted via the urine</li> <li>Administered orally (on its own) or Administered in a combination with a sulphomethoxazole (a sulphonamide) in oral and IV form.</li> </ol> Signup and view all the answers

What is the mode of action of Trimethoprim?

It inhibits Folic acid synthesis as it is a key intermediate metabolism. Folic acid vitamin is required for synthesis of key cellular components like thymidine, purines etc. Signup and view all the answers

What are the side effects of Penicillins?

hypersensitivity/skin reactions Signup and view all the answers

What is the side effect of Flucloxacillin and co-amoxiclav?

cholestatic jaundice Signup and view all the answers

What is the side effect of Clindamycin, cephalosporins and quinolones?

C. difficile colitis Signup and view all the answers

What are the side effects of Macrolides?

GI disturbances, hepatitis, Q-T interval Signup and view all the answers

What are the side effects of Quiolones?

Q-T interval, convulsions, tendonitis Signup and view all the answers

What are the side effects of Aminoglycosides/glycopeptides?

nephrotoxicity/ototoxicity Signup and view all the answers

What are the side effects of Vancomycin?

‘red man’ syndrome Signup and view all the answers

What are the side effects of Tetracyclines?

hepatotoxicity, staining teeth, photosensitivity, dysphagia Signup and view all the answers

What are the side effects of Nitrofuratoin?

peripheral neuropathy, pulmonary fibrosis Signup and view all the answers

What are the side effects of Chloramphenicol?

aplastic anaemia, grey baby Signup and view all the answers

What are the side effects of Linezolid?

blood dyscrasias, MAOI, optic neuropathy Signup and view all the answers

What are the side effects of Sodium fusidate?

hepatotoxicity Signup and view all the answers

What are the side effects of Sulphamides (co-trimoxazole)?

Stevens-Johnson syndrome, blood dyscrasias Signup and view all the answers

What are the side effects of Trimethoprim?

blood dyscrasias Signup and view all the answers

What are the potential interactions between enzyme inhibitors and certain antibiotics?

Enzyme inhibitors interact with erythromycin, clarithromycin, isoniazid, metronidazole, ciprofloxacin. Signup and view all the answers

Which antibiotic is affected by enzyme inducers?

Rifampicin is affected by enzyme inducers. Signup and view all the answers

What can reduce the absorption of tetracyclines and quinolones?

Antacids/calcium can reduce the absorption of tetracyclines and quinolones. Signup and view all the answers

What can lead to contraceptive failure when taken with broad-spectrum antimicrobials?

Entero-hepatic cycling can lead to contraceptive failure when taken with broad-spectrum antimicrobials and oral contraceptives. Signup and view all the answers

What happens when broad-spectrum antimicrobials are taken with warfarin?

Taking broad-spectrum antimicrobials with warfarin leads to increased INR. Signup and view all the answers

What are the potential interactions between Metronidazole and alcohol?

Metronidazole can cause a disulfiram-like interaction with alcohol. Signup and view all the answers

What are the potential interactions between Quinolones, steroids, and NSAIDs?

Quinolones can interact with steroids, leading to tendonitis, and with NSAIDs, leading to convulsions. Signup and view all the answers

What are the potential interactions between Macrolides, Quinolones, and Q-T prolonging drugs?

Macrolides and Quinolones can interact with Q-T prolonging drugs. Signup and view all the answers

What is the potential interactions with Glycopeptides and what does it lead to?

Aminoglycosides/glycopeptides/colistin with loop diuretics or ciclosporin or tacrolimus - nephrotoxicity Signup and view all the answers

Study Notes

Important Side Effects of Antibiotics

Penicillins: Hypersensitivity and skin reactions are common side effects.
Flucloxacillin & Co-amoxiclav: Associated with cholestatic jaundice.
Clindamycin, Cephalosporins & Quinolones: Can lead to C. difficile colitis.
Macrolides: Causes gastrointestinal disturbances, hepatitis, and prolongation of the Q-T interval.
Quinolones: Known to cause Q-T interval prolongation, convulsions, and tendonitis.
Aminoglycosides & Glycopeptides: Risk of nephrotoxicity and ototoxicity.
Vancomycin: Notable for causing 'red man' syndrome.
Tetracyclines: Linked to hepatotoxicity, teeth staining, photosensitivity, and dysphagia.
Nitrofurantoin: Possible side effects include peripheral neuropathy and pulmonary fibrosis.
Sulphamides (Co-trimoxazole): Associated with Stevens-Johnson syndrome and blood dyscrasias.
Trimethoprim: Can cause blood dyscrasias.
Chloramphenicol: Risk of aplastic anaemia and grey baby syndrome.
Linezolid: Potential for blood dyscrasias, MAOI interactions, and optic neuropathy.
Sodium fusidate: Known to cause hepatotoxicity.

Drug Interactions with Antibiotics

Enzyme Inhibitors: Interact with erythromycin, clarithromycin, isoniazid, metronidazole, and ciprofloxacin.
Enzyme Inducers: Rifampicin interacts with enzyme inducers.
Antacids/Calcium: Reduce absorption of tetracyclines and quinolones.
Broad-Spectrum Antimicrobials: Can interfere with oral contraceptives leading to contraceptive failures due to entero-hepatic cycling.
Warfarin: Use of broad-spectrum antimicrobials can increase INR.
Metronidazole: Causes disulfiram-like reactions with alcohol.
Aminoglycosides/Glycopeptides/Colistin: When combined with loop diuretics, ciclosporin, or tacrolimus, there’s a heightened risk for nephrotoxicity.
Quinolones and Steroids/NSAIDs: Co-administration can lead to tendonitis or convulsions.
Macrolides/Quinolones and Q-T Prolonging Drugs: Increased risk of Q-T prolongation when combined.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the administration and excretion of antibiotics. Learn about the different routes of administration, absorption rates, and excretion pathways involved.