Antimicrobial chemotherapy (better cue cards Flashcards by Adam Moughal

Define ‘bactericidal’

Antimicrobial that kills bacteria

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Define bacteriostatic

Antimicrobial that inhibits growth of bacteria

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Define ‘sensitive’

Level of anti-microbial required to inhibit/kill organism at infection site

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Define ‘resistant’

Organism not killed/inhibited by levels of antimicrobial available at site of infection

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Define ‘MIC’

Minimal inhibitory concentration - minimum conc. of antimicrobial needed to inhibit visible growth of given organism

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Define ‘MBC’

Minimal bactericidal conc. - Minimum conc. of antimicrobial needed to kill organism

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What are the 3 routes of administration

Systemic - taken internally
Topical - Applied to surface, eg skin
Parenteral - Administered intra-venously (iv) / intra-muscularly (im)

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What are the 3 mechanisms of action of antimicrobial agents

Inhibition of cell wall synthesis (humans don’t have cell walls)
Inhibition of protein synthesis
Inhibition of nucleic acid synthesis

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What do Beta lactams Do

Disrupt peptidoglycan synthesis
Inhibiting Penicillin-binding proteins

Peptidoglycan Important structure of bacteria cell wall

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what two types of drugs are β-lactams

Penicillin
Cephalosporins

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What are the two types of antimicrobials which inhibit cell wall synthesis

Glycopeptides and β-lactams

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What are two common glycopeptides

Vancomycin
Teicoplanin

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Describe the mechanism and range of action of glycopeptides

inhibit cell wall synthesis - but at a prior stage than B-lactams
Act only on gram positive organisms

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What route of administration must glycopeptides take (unless special circumstances)

Parenterally (iv/im)

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What is one side effect of vancomycin

It is toxic

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What are the 4 types of antimicrobials which inhibit protein synthesis

Aminoglycosides - gram -ve
Macrolides and tetracyclines - gram +ve
Oxazolidinones - gram +ve
Cyclic lipopeptides - gram +ve

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What type of bacteria are aminoglycosides useful for?

Treating serious gram negative Infection

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What type of drug is gentamicin and what is a common side effect of adminsitration

Aminoglycoside and is toxic -
Requires careful dosing regime & monitoring of levels

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What are the uses of macrolides and tetracyclines

Treatment of gram positive infections in patients who are penicillin allergic CANNOT BE USED WITHOUT LABORATORY TESTING

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What class of drug is linezolid and what is it commonly used for?

oxazolidonones (protein synthesis inhibitor).
good activity against MRSA
Can be given orally

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What class of drug is daptomycin and what it is commonly used for?

Cyclic lipopeptide (protein synthesis inhibitor).
Activity against gram positives in general and MRSA

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What are the 2 classes of drug which inhibit nucleic acid synthesis

Trimethoprim
Sulphamethoxazole
Used in combination to form a drug
- Co-trimoxazole

- Fluoroquinolone’s

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What type of drug is ciprofloxacin? What it is commonly used for? What are some of the drawbacks of the drug

Fluoroquinolone (nucleic acid inhibitor).
used against gram negative organisms.
Taken orally
Not to be used in children

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Describe inherent or intrinsic resistance

All strains of a given species naturally resistant to antibiotic
Due to inability of drug to penetrate bacterial cell wall

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What are the 2 ways in which acquired resistance may be acquired?

1. A spontaneous mutation 2. Genes that code for resistance spread from organism to organism through plasmids

What are the 2 mechanisms of resistance to β–lactam antibiotics?

1. β-lactamase production - enzymes which cleave β–lactam ring of antibiotic & render it inactive 2. Alteration of penicillin binding protein (PBP) target site - Mutations in PBP genes result in a modified target site B-lactams no longer bind

2 ways to combat B-lactamase?

1. Co-amoxiclav plus the B lactamase inhibitor clauvanic acid 2. Flucloxacillin - modified form of penicillin

What are ESBL's and what are the implications of their existence

Extended spectrum β–lactamases (ESBLs) Produced by Gram negative organisms. Break down third generation cephalosporins & penicillins Render organism resistant to all β–lactam antibiotics

What glycopeptide resistant bacteria has appeared recently and what are the implications of this mutation?

Vancomycin resistant enterococci (VREs) Major problem: Resistance might spread from enterococci to Staph aureus producing vancomycin resistant staph aureus

Describe the spectrum of Benzyl penicillin (penicillin G)

Gram +ve organisms intra-venous treatment of serious pneumococcal, meningococcal and strep pyogens

Describe the spectrum of amoxicillin/ampicillin

Gram -ve activity Oral absorption Effective against streptococci and coliforms

Describe the spectrum of co-amoxiclov

Effective against B-lactamase producing coliforms

Describe the spectrum of flucloxacillin

Effective against staph infections

Describe the spectrum of piperacillin

Gram -ve cover Effective against Enterococcus faecalis and pseudomonas species

Describe the spectrum of cephalosporins

Activity against Gram -'ve organisms increases from 1st through 3rd generation Activity against Gram +'ve organisms decreases from 1st through 3rd generation Generally not used as encourage C Diff infections

How must cephalosporins be taken?

Parenteral use only

Describe the spectrum of aminoglycocides

Noted for action against Gram -ve organisms Effective against staphlococci but not streptococci Gentamicin cheapest and most common aminoglycocide

Describe the spectrum of glycopeptides

Only gram +'ve organisms are affected (anaerobic +aerobic) | Vancomycin most common example

Describe the spectrum of action of macrolides

Mainly used against gram +'ve organisms - Alternative to penicillin for patients with a penicillin allergy

Describe the spectrum of action of Quinolones

Nearly all gram -'ve organisms are sensitive | Mainly used in treatment of community acquired pneumonia

Describe the spectrum of action of metronidazole

Effective against Gram +'ve and -'ve anaerobes

Describe the spectrum of action of fusidic acid

staphylococcal drug

Describe the spectrum of action of trimethoprim

Used in urinary infections

Describe the spectrum of action of tetracyclines

Used in genital tract and respiratory tract infections

Describe the spectrum of action of clindamycin

Effective against Gram +'ve organisms

What infection is linezolid used against

MRSA

What infection is fidaxomicin used against

C. diff

What infection is daptomycin used against?

MRSA

What are the 4 classes of anti-fungal drugs?

Polyenes Azoles Allylamines Echinocandins

Describe the mechanism of polyenes

Bind to the ergosterol- present in fungal wall Also binds to mammalian sterols making polyenes TOXIC

Describe the use of amphotericin B and Nystatin (Hint: they are Polyenes)

Amphotericin B is used intra-venously for serious yeast infections and other fungal infections. Very toxic. Nystatin is used topically or in oral suspension and is not an intra-venous agent for serious fungal infection

Describe the mechanism of Azoles

Inhibit ergosterol synthesis

What is fluconazole used to treat?

Yeast infections

What are voriconazole and intraconazole used to treat?

Yeast and filamentous fungi including: Aspergillosis

Describe the mechanism of allylamines

They suppress the ergosterol synthesis but act at a different stage of the synthetic pathway from azoles

Describe the use of Terbinafine

Used for fungal infections of the skin and nails

Describe the mechanism of echinocandinds

They inhibit the synthesis of glucan polysaccharide in several types of fungi

What are echinocandins used for?

Serious candida and aspergillus infections

Describe anti-herpes virus drugs

All become latent and include: Herpes simplex virus (HSV), eptein-barr virus (HBV), cytomegalovirus (CMV) and Varicella-Zoster Virus (VZV).

Describe the mechanism and function of Aciclovir

not very toxic Extremely active against HSV and active against VZV Intravenously used for serious, Oral for less serious

Describe the use of valaciclovir and famciclovir

Related to aviclovir - Used in oral treatment of HSV and shingles

Describe the use of valganciclovir

Pro drug of ganciclovir -> alternative treatment for CMV. | High levels of bone marrow toxicity

Describe the use of foscarnet

Used for HSV, VZV and CMV | Highly nephrotoxic

Describe the use of Cidofovir

Used for CMV retinitis

What anti-viral agent is used to treat infections with HIV?

Saquinavir