Microbiology- Ch. 20 Antimicrobial Drugs

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

Selective toxicity

A drug that kills harmful microorganisms without damaging the host

1928

Fleming discovered penicillin, produced by Penicillium fungus (mold)

1940

First clinical trials of penicillin performed

Beta Lactam Antibacterials

Inhibit formation of cross-linking peptides in peptidoglycan

beta lactam antibacterial

Penicillin is a __________________

Natural penicillins

a class of β-Lactam Antibacterials (penicillins) that are effective primarily against gram-positive bacteria

Semisynthetic penicillins

Several of these β-Lactam Antibacterials (penicillins) are effective against both gram-positive and gram-negative bacteria

penicillin G and V

2 natural β-Lactam Antibacterials (penicillin)

oxacillin and ampicillin

2 semisynthetic β-Lactam Antibacterials (penicillin)

penicillin G

natural penicillin that requires injection

penicillin V

natural penicillin that can be taken orally

oxacillin

semisynthetic penicillin that has a narrow spectrum to only for gram positives, resistant to penicillinase

ampicillin

semisynthetic bacterium with an extended spectrum, many gram negatives

penicilloic acid

penicillinase breaks down penicillin to ______________ _____________ (and takes away the Beta-lactam ring in the process)

Cephalosporins, Carbapenems, Penicillin

3 beta-Lactam Antibiotics

Cephalosporins

Derived from Cephalosporium fungus

Examples: cephalexin, cephadrine, and ceftriaxone

up to 15% of individuals who are allergic to penicillins are also allergic to cephalosporins

Carbapenems

Two-part drugs: a β-lactam and a compound that prevents its degradation in the kidneys

Very broad spectrum: Ex. Primaxin

cephalosporins

up to 15% of individuals who are allergic to penicillins are also allergic to ____________________

bacitracin and vancomycin

2 polypeptide antibiotics/inhibitors of cell wall synthesis

bacitracin

a polypeptide antibiotic that is a topical application for superficial infections

Targets gram-positives (streptococci and staphylococci)

vancomycin

a polypeptide antibiotic that is derived from species of Streptomyces found in the jungles of Borneo

Narrow spectrum use against gram-positives

One of our last defenses against methicillin-resistant S. aureus (MRSA)

Vancomycin-resistance in bacteria is considered a medical emergency since few alternatives exist

Isoniazid and Ethambutol

2 Anti-Mycobacterium antibiotics

Isoniazid

an anti-mycobacterium antibiotic that inhibits mycolic acid synthesis by mimicking two vitamins, niacin and pyridoxal

Ethambutol

an anti-mycobacterium antiobiotic that inhibits incorporation of mycolic acid into mycobacterial cell wall

Given concurrently with isoniazid and is effective against slow-growing mycobacteria, such as M. leprae

ethambutol

Given concurrently with isoniazid and is effective against slow-growing mycobacteria, such as M. leprae

chloramphenicol

Binds 50S subunit and inhibits peptide bond formation

chloramphenicol

Usually not a first choice antibiotic due to host toxicity (causes bone marrow damage)

chloramphenicol

Broad spectrum

Binds 50S subunit and inhibits peptide bond formation

Usually not a first choice antibiotic due to host toxicity (causes bone marrow damage)

Aminoglycosides

Target the 30S subunit of the ribosome

Aminoglycosides

Not widely used today unless other treatments fail

Have host toxicity

Can affect the auditory nerve and cause hearing damage (neurotoxicity)

Can also damage kidneys (nephrotoxicity)

auditory

neurotoxity causes damage to the ___________________ nerve, caused by aminoglycosides

kidneys

nephrotoxicity causes damage to the _________________, caused by aminoglycosides

aminoglycosides

Examples: streptomycin, neomycin, gentamicin

aminoglycosides

Broad spectrum

Target the 30S subunit of the ribosome

Examples: streptomycin, neomycin, gentamicin

Not widely used today unless other treatments fail

Have host toxicity

Can affect the auditory nerve and cause hearing damage (neurotoxicity)

Can also damage kidneys (nephrotoxicity)

oxacillin

a semisynthetic penicillin that is resistant to penicillinase

bacitracin

a polypeptide antibiotic that targets gram-positives (streptococci and staphylococci)

penicillins

all _____________ have a Common nucleus and Beta-lactam ring

polypeptide

________________ and anti-mycobacterium antibiotics are inhibitors of cell wall synthesis

bacitracin, vancomycin, isoniazid, ethambutol

4 inhibitors of cell wall synthesis

chloramphenicol, aminoglycosides, tetracyclines, macrolides

4 inhibitors of protein synthesis

oxacillin

semisynthetic penicillin with a narrow spectrum (only gram positives)

ampicillan

semsynethic penicillin with an extended spectrum (many gram negatives)

tetracycline

interfere with tRNA attachment on the 30S subunit of the ribosome

tetracycline

together with Beta-lactams, comprise the two most important classes of antibodies in clinical medicine

tetracycline

interfere with tRNA attachment on the 30S subunit of ribosome

together with Beta-lactams, comprise the two most important classes of antibiotics in clinical medicine

macrolides

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

examples: erythromycin, azithromycin, clarithromycin

macrolides

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

examples: erythromycin, azithromycin, clarithromycin

often used in place of Beta-lactams for allergic patients

macrolides

often used in place of Beta-lactams for allergic patients, target the 50S unit of the ribosome (prevent translocation)

rifampin

inhibits Transcription (RNA synthesis)

rifampin

inhibits transcription (RNA synthesis)

used mainly to treat tuberculosis and leprosy

an odd side effect is the appearance of reddish-orange urine, feces, saliva, sweat, and tears

rifampin

used mainly to treat tuberculosis and leprosy, an odd side-effect is the appearance of reddish-orange urine, feces, saliva, sweat, and tears

quinolones

inhibit DNA replication by inactivating DNA gyrase

often used in treatment of urinary tract infections (UTIs)

example: ciproflaxin (cipro)

quinolones

often used in treatment of urinary tract infections (UTI's)

example: ciproflaxin (cipro)

sulfa drugs (sulfonamides)

inhibit folic acid synthesis

most widely used example is a combination of trimethoprim and sulfamethoxazole (TMP-SMZ)

cell wall

echinocandins inhbit _______ _______ synthesis

ex. candidas is used against the species of Candida

polyenes

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

ex. amphotericin B and nystatin

polyenes

amphotericin B and nystatin are examples of _______________

griseofulvin

inhibits fungal division

used for superficial fungal infections of skin, hair, and nails

tolnaftate (tinactin) and terbinafine (lamisil)

topical over-the-counter fungicides for athlete's foot and jock itch

tinactin

another word for the fungicide tolnaftate is ___________

lamisil

another word for the fungicide terbinafine is ______________

oseltamivir (tamiflu) and zanamivir (relenza)

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

tamiflu

another word for oseltamivir (blocks neuraminidase activity of influenza A and B viruses, inhibiting viral release from the host)

relenza

another word for zanamivir (blocks neuraminidase activity of influenza A and B viruses, inhibiting viral release from the host)

R plasmids

resistance genes are often on ___________ that can be transferred between bacteria

blocking entry, inactivating enzymes, alteration of target molecule, efflux of antibiotic

4 forms of resistance to antibiotics

interferons

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

interferon

imiquimod- drug that promotes ______________ production

macrolides

examples: erythromycin, azithromycin, clarithromycin targets the 50S subunit of the ribosome (prevents translocation)

quinolone

inhibit DNA replication by inactivating DNA gyrase

polyenes

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

polymyxin B

topical application for gram-negative infections, especially those caused by Pseudomonas

Combined with bacitracin and neomycin in an over-the-counter preparation

one of the few antibiotic preparations that does not require a prescription

polymyxin B

one of the few antibiotic preparations that does not require a prescription