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38 Cards in this Set

  • Front
  • Back

chemotherapy

the use of drugs to treat a disease

antimicrobial drugs

interfere with the growth of microorganisms within a host

antibiotic

a substance produced by a microorganism that inhibits another microorganism

Fleming

accidentally discovered penicillin in 1928 based on an area of inhibition of bacterial growth.




in 1940 the first clinical trials of penicillin were performed. Penicillin was the first antibiotic.

do human cells have cell walls?

no. this is why antimicrobial drugs do not kill human cells.

action of antimicrobial drugs

inhibition of cell wall synthesis


inhibition of protein synthesis


inhibition of synthesis of essential metabolites


injury to plasma membrane

beta Lactam antibacterials

inhibit formation of cross linking peptides in peptidoglycan




can't form mesh of cell wall without the cross linking

natural penicillins

effective against gram (+) bacteria


Penicillin G (injection)


Penicillin V (oral)

semisynthetic penicillins

oxacillin: narrow spectrum, only gram (+), resistant to penicillinase




ampicillin: extended spectrum, many gram (-)

penicillinase

enzyme that breaks open the beta lactam ring. tuns penicillin into penicilloic acid.

cephalosporins

derived from Cephalosporium fungi.


cephalexin, cephadrine, and ceftiaxone.




15% of those allergic to penicillin also allergic to cephalosporins

carbapenems

two part drug


B lactam and a compound that prevents its degradation in the kidney


broad spectrum


primaxin

polypeptide antibiotics

bacitracin (topical, +)


vancomycin (found in jungles of Bornea, narrow spectrum, +)



anti-mycobacterium antibiotics

isoniazid: inhibits mycolic acid synthesis by mimicking two vitamins, niacin, and pyridoxal (vit B6)


Ethambutol

ethambutol

inhibits incorporation of mycolic acid in bacterial cell walls

Inhibitors of protein synthesis (effect ribosome)

chloramphenicol


aminoglycosides


macrolides


tetracyclines

chloramphenicol

broad spectrum


binds 50S subunits and inhibits peptide bond formation


host toxicity (not usually first choice drug)

aminoglycosides

broad spectrum


target 30S subunit of the ribosome


streptomycin, neomycin, gentamicin


not widely used: host toxicity




can affect auditory nerve and kidney

tetracyclines

broad spectrum


interfere with tRNA attachment on 30S subunit of ribosome


forms complexes with calcium that causes damage to teeth and bones

macrolides

target the 50S subunit of the ribosome (prevent translocation)




erythromycin, axithromycin, clarithromycin




often used in place of B lactase for allergic ppl.

cause injury to the plasma membrane

polymyxin B

Polymyxin B

topical application for gram-negative infections, especially those caused buy species of Pseudomonas




do not require prescription

inhibitors of nucleic acid synthesis

Rifampin


Quinolones

Rifampin

inhibits transcription (RNA synthesis)


used to treat TB and leprosy


side effect: reddish-orange urine, other secretions

Quinolones

inhibit DNA replication by inactivating DNA gyrase


used to treat UTIs


Cipro


bacteriostatic

competitive inhibitors

sulfonamides (sulfa drugs)


inhibit folic acid synthesis; enzyme can't work on substrate due to a competitive inhibitor




broad spectrum


Bactrim



anti fungal drugs

Echinocandins


Polycenes

Echinocandins

inhibit cell wall synthesis


ex: cancidas is used against species of the yeast Candida

Polyenes

inhibit ergosterol synthesis in fungal cell membrane, causing membrane permeability and cell death


ex: Amphotericin B and Nystatin

other anti fungal drugs

Griseofulvin


Tolnaftate (Tinactin) and Terbinafine (Lamisil)

Griseofulvin

inhibits fungal cell division


oral med used for superficial fungal infections

Tolnaftate (Tinactin) and Terbinafine (Lamisil)

topical over-the-counter meds for athletes foot

antiviral drugs

nucleoside analogs (acyclovir activity)


Oseltamivir (Tamiflu)/Zanamivir (Relenza)


interferons

nucleoside analogs

mimin structures of purines (A,G) and pyrimidines (C,T)

Oseltamivir (Tamiflu)/Zanamivir (Relenza)

block neuraminidase activity of influenza A and B viruses, inhibiting viral release from the host




must be taken within 24 hours of infection

interferons

released by virus-infected cells and induce neighboring cells to synthesize antiviral proteins

imiquimod

drug that promotes interferon production

mechanisms of antibiotic resistance

enzymatic destruction of drug

blocking entry of drug


alteration of drug's target site


rapid ejection (efflux) of the drug