Antimicrobial Chemotherapy Flashcards by Hannah Thomas

Give three mechanisms by which bacteria can be resistant to antibiotics

bacteria produce an enzyme which breaks down the antibiotic (e.g. B-lactamase attacks penicillin)
genetic alteration in target site within the organism means that the antibiotic is ineffective (e.g. MRSA)
bacteria acquires an efflux pump, which pumps the antibiotic out of the cell (e.g. macrolide resistance)

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What class do penicillins and cephalosporins belong to?

Beta-lactam antibiotics

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Give four examples of penicillins

Benzylpenicillin (penicillin G)
Flucloxacillin
Amoxacillin
Co-amoxiclav

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Give an example of each generation of cephalosporin

1st generation: cephalexin
2nd generation: cefuroxime
3rd generation: ceftriaxone
4th generation: cefepime

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Give two drug classes which are effective against staph and strep. Give an example of a drug that belongs to each class.

Macrolide: clarithromycin, azithromycin and erythromycin
Lincosamide: clindamycin

(note: macrolides are also useful against atypical pneumonia)

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Give two drug classes which are effective against Pseudomonas (and other gram-negative organisms). Give an example of a drug that belongs in each class.

Fluoroquinolone: ciprofloxacin
Aminoglycoside: gentamycin

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Which organisms are sensitive to gentamycin?

Gram-negative bacteria, including pseudomonas
Staph aureus
(NOT streptococcus)

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Which antibiotic is effective against MRSA? Which class does this drug belong to?

Vancomycin (a glycopeptide antibiotic)

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How is vancomycin administered?

IV unless treating Clostridium dificile in which case it should be given orally

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Which antibiotic(s) are effective against Clostridium dificile?

Metronidazole

Vancomycin

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Give two antibiotics which are used to treat UTIs

Trimethoprim

Nitrofurantoin

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Give an example of a carbapenem. Which organisms are susceptible to this drug?

Meropenem

Has a wide spectrum, including anaerobes

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Which organisms are sensitive to metronidazole?

Anaerobes - including Clostridium dificile

Parasites

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Give an example of a tetracycline, and four organisms that are sensitive to this class of drugs.

Doxycycline

Sensitive organisms:

chlamydia
borrelia (Lyme)
brucella
rickettsia

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How to B-lactams work?

B-lactams are bactericidal; they inhibit cell wall synthesis, causing autolysis of the bacteria cell and therefore the death of the organism.

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Which antibiotic is teratogenic, nephrotoxic and ototoxic?

Gentamycin

Are antiviral drugs viricidal or virustatic?

All antivirals are virustatic

Give four examples of anti-herpes drugs

Aciclovir
Famciclovir
Ganciclovir
Foscarnet
Cidofovir

Give four organisms which are sensitive to aciclovir

herpes simplex virus (HSV)
Epstein-Barr virus (EBV)
varicella zoster virus (VZV)
cytomegalovirus (CMV)

Give two examples of nucleoside analogue reverse transcriptase inhibitors. Which virus are they used to treat?

Ziduvudine (AZT)
Lamivudine
Abacavir

Treat HIV infection

Give four drugs which can be used to treat hepatitis B

adefovir
tenofovir
entecavir
telbivudine

Give three drugs which can be used to treat hepatitis C

interferon alpha
ribavarin (oral)
lamivudine

Give two drugs which can be used to treat influenza A and B. What is the condition for administering these drugs?

Zanamavir
Oseltamivir

Must be administered within 48 hours of symptom onset in order to be effective

Give four classes of antifungal drugs

Polyenes
Azoles
Allylamines
Echinocandins

Which antifungal drugs can be given IV to treat systemic fungal infection?

Amphotericin B | Caspofungin

Give two drugs which belong to the polyene class of antifungals. How to polyenes work?

Amphotericin B Nyastatin Work by increasing the permeability of the fungal cell wall

How do azoles work? Give three drugs which belong in this class

Inhibit ergosterol synthesis - Fluconazole (acts on yeast) - Itraconazole (acts on both yeasts and filliforms) - Voriconazole (treats invasive aspergillosis)

What is terbinafine?

An allylamine antifungal agent Inhibits ergesterol synthesis Usually used to treat dermatophytes

What is caspofungin?

An echinocandin antifungal agent Inhibits synthesis of glucan polysaccharide Usually given IV to treat severe candida and aspergillus infections

Describe the regime for treating tuberculosis

6 months of Rifampicin and Isoniazid | First two months supplemented with Pyrazinamide and Ethambutol

What side effects are associated with Rifampicin?

Red/orange urine Itch Thrombocytopenia (Liver toxicity/hepatitis)

What side effects are associated with Isoniazid?

Peripheral neuropathy | Liver toxicity

What side effects are associated with Ethambutol?

Visual disturbances | also contra-indicated in renal impairment

What side effects are associated with Pyrazinamide?

Rash | Liver toxicity

Give an example of a second-line tuberculosis drug

Streptomycin

For which organism(s) is benzylpenicillin usually the first choice?

Neisseria meningitidis Strep pneumoniae Strep pyogenes

For which organism(s) is flucloxacillin usually the first choice?

Staphylococcus aureus

For which organism(s) is amoxicillin (and co-amoxiclav) usually the first choice?

Streptococci Enterococci Staph aureus Gram negatives (but not pseudomonas) - co-amoxiclav has better action against gram negatives due to inhibiton of beta-lactamase enzymes

For which infections are cephalosporins often the first choice?

Pneumonia and meningitis - gram-negative organisms (except Pseudomonas) - streptococci