- antibacterial - antifungal - antiprotozoal - antiviral

- mode of action varies - e.g. inhibit cell wall synthesis; inhibit protein synthesis etc

block 2 SG+ slides Flashcards by Jane Andrea De Leon

bactericidal

eg.penicillins

antibacterials may kill the organism

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bacteriostatic

eg. tetracyclines

retard the growth of the organism

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Chemotherapeutic drugs

Drugs that work to kill or retard the growth

of cells. eg antimicrobial drugs, anticancer drugs

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antimicrobial drugs

antibacterial
antifungal
antiprotozoal
antiviral

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does antimicrobial drugs narrow or broad?

penicillin G- narrow(gram -
tetracyclines & cephalosporins- broad (+-)

they can have a narrow spectrum [effective against a limited range of organisms] of activity or broad spectrum [effective against a wide
range of species] of activity

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four basic mechanisms of action by which antimicrobial agents can destroy or retard the growth of microbes
MOA

-Inhibit cell wall synthesis
-Alter cell membrane
permeability
-Inhibits protein synthesis
-Interfere with cellular
metabolism

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what are cidal drugs?

Drugs that inhibit cell wall synthesis or disrupt the cell membrane

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what are static drugs?

Drugs that inhibit protein synthesis or interfere with nucleic acid synthesis are

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Common Adverse Effects of Antimicrobial Drugs

Allergic or hypersensitivity reactions
Superinfection
Organ toxicity
Diarrhoea

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Allergic or Hypersensitivity Reactions

may be mild reactions which can be treated with antihistamines. Severe reactions (e.g. anaphylactic shock) will occur within 20 minutes and treatment will involve adrenaline (epinephrine), bronchodilators and antihistamines.

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Superinfection or Opportunistic Infections

secondary infection that occurs when the normal microbial flora of the body is disturbed during antibiotic therapy. eg. Candida albicans, staphylococci and pseudomonas

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Organ Toxicity

Liver and kidney are involved in metabolism and elimination hence antimicrobial may result in damage in these organs. eg colitis( inflamed colon)

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Principles of antimicrobial therapy

Identify if infection is ‘real’.
Take appropriate specimens.
Are drugs necessary?
Need for urgent therapy before lab results are known?
Use appropriate drug, dose and route of administration.
Monitor success of therapy.
Combinations of antimicrobials to be used?
Can use antibiotics prophylactically occasionally e.g. isoniazid in TB, doxycycline in malaria prophylaxis.

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Antimicrobial resistance

Microorganisms can develop resistance to antibiotics by mutating existing genes or by acquiring new genes from other strains or species.
-threatens the effective prevention and treatment of an ever-increasing range of infections caused by bacteria, parasites, viruses and fungi

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Antimicrobial resistance

Resistance to bacteria
– e.g. K. pneumoniae, E.coli,
S. aureus

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Antimicrobial resistance

Resistance in conditions

– e.g. malaria, TB, HIV, influenza

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how does antibiotic resistance occur?

naturally over time, but the
misuse and overuse of antibiotics in humans and animals has accelerated
the process.

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what is Acquired resistance ?

when the organism develops resistance to the drug

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what are Antibiotics?

a substance produced by a microorganism that
is effective in killing or inhibiting the growth of
other microorganisms

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Antibiotics MOA

mode of action varies - e.g. inhibit cell wall synthesis; inhibit protein synthesis etc

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Penicillins drugs

– penicillin, amoxicillin, flucloxacillin, Augmentin

Cephalosporins drugs

cefalexin, cefaclor, cefuroxime,

Aminoglycosides drugs

gentamicin, neomycin

Macrolides drugs

– erythromycin, clarithromycin,

azithromycin

Tetracyclines drugs

doxycycline, tetracycline

Quinolones drugs

ciprofloxacin, norfloxacin

what does penicillins contain?

-lactam ring which inhibits formation of peptidoglycan crosslinks in bacterial cell walls

Resistance

usually the result of production of penicillinase (also termed B-lactamase) an enzyme released by some bacteria which destroys the B- lactam ring.

Penicillin G

-narrow spectrum -very unsatable acid stability not penicillinase resistant

Penicillin V

- narrow - relatively stable - no

ampicillin

- broad - stable - no

amoxicillin

- broad - stable - no

flucloxacillin

- narrow - relatively stable - yes

Tetracyclines | eg. doxycycline, tetracycline

broad spectrum and bacteriostatic and work by binding to the smaller ribosomal subunit thereby interfering with protein synthesis.

Tetracyclines adverse effect

GI upset, superinfection, renal impairment, discolouration and deformity in growing teeth and bones.

Aminoglycosides | eg. gentamicin, neomycin, tobramycin.

bactericidal and their mode of action is causing | misreading of the mRNA by the ribosome and this means that abnormal protein production occurs

Aminoglycosides adverse effects

nephrotoxicity and ototoxicity.

Quinolones | Examples: ciprofloxacin, norfloxacin

broad-spectrum antibiotics and bacteriostatic. They work | by inhibiting DNA synthesis of the bacteria, thereby retarding its growth.

Quinolones adverse effects

GI disturbances, rash, headache, dizziness | and superinfections.

antiseptics use

killing or inhibiting the growth of microorganisms on human beings and the use of metronidazole, an antiprotozoal, used in the treatment of giardiasis.

how are antiseptics classified?

according to their mode of action which is usually | chemical in nature

eg- Alcohols

Denatures the proteins in cells and can dissolve membrane lipids. eg; ethanol & isopronol

Antiprotozoal drugs

used to treat or prevent infection caused by | microorganisms called protozoa.

what is Giardiasis ?

one of the most common protozoal infections.

symptoms of giardiasis

chronic diarrhoea, dehydration, nausea, | flatulence, abdominal pain, and weight loss.

Treatment:

- fluid and electrolyte replacement | - metronidazole.

how does Metronidazole works?

enters the protozoal cell and interferes with DNA replication thereby killing the protozoa

adverse effects of metronidazole

nausea, headaches, | abdominal cramping, a metallic taste in the mouth, and fatigue.

Drug interactions:

With alcohol – nausea, abdominal cramps, headaches & flushing (disulfiram -like reaction) Potentiates action of warfarin, phenytoin. Cimetidine may decrease the clearance of metronidazole

what is Antifungal?

a drug that is used to kill or | inactivate fungi and hence treat fungal (including yeast) infections

Antifungal drugs

- amphotericin B - azoles (clotrimazole, miconazole) - terbinafine

Antiretroviral agents

- zidovudine (AZT) - efavirenz - atazanavir - dolutegravir