Antimicrobic Chemotherapy

Question 1

Antimicrobic

Answer 1

Any substance that may be used systematically to KILL or INHIBIT microbial pathogens

Question 2

Antimicrobic chemotherapy

Answer 2

The use of antimicrobics to treat infectious diseases (can be bacterial/ viral microorganisms)

Question 3

Therapeutic dosage level

Answer 3

LEVEL of Antimicrobic that ELIMINATES the organism systematically

Question 4

Minimum inhibitory concentration (MIC)

Vs.

Minimum lethal concentration (MLC)

Answer 4

MIC- anti-microbic concentration that inhibits growth

MLC-anti-microbic concentration that kills a pathogen

Question 5

Broad vs narrow spectrum antimicrobic

Answer 5

Broad- effective against wide range of microorganisms

Narrow- effective against few

Question 6

Antibiotic

Answer 6

Substance produced by a microorganism that kills or inhibits other microorganisms.

Can be derived from natural source, chemically altered (semi-synthetics), or totally synthesized in a lab

Question 7

Antimicrobic resistance

Answer 7

Property of a microbe that enables it to tolerate a specific drug

Question 8

Combined therapy

Answer 8

Is synergistic therapy, where antimicrobics are used in combination to treat resistant microorganisms (interaction = increased effectiveness)

Question 9

One-step resistance

Answer 9

One step process (such as point mutation) that confers antimicrobic resistance or modified ribosomes / enzymes that are no longer affected by a competitive inhibitor

Question 10

Multi step resistance

Answer 10

Successive mutation populations that emerge over a period of time that can tolerate higher doses of anti-microbic.this is selected for by exposures to anti-microbics.

Question 11

Super infection

Answer 11

Overgrowth of a resistant strain which usually will displace microbial flora.

Question 12

Sulfonamides

Answer 12

Sulfa drugs/ isolated sulfanilamide from the red stain prontosil.

Over 5,000 derivatives, few used due to being toxic.

Action: act as competitive inhibitors of folic acid synthesis by competing with p-ABA for the active site on the enzyme foliage synthetase. No production of folic acid means cells cannot produce proteins/nucleus acids for growth.
Are bacteriostatic, and generally effective against staph, strept, neisseria and rickettsias.

Used mainly in treatment of:
Meningococcal meningitis caused by neisseria meningitis (now resistant strains)
UTIs caused by gram neg bacteria

Sulfamerazine/ triple sulfa/ septra/ bactrim

Question 13

Antibiotics

Answer 13

Originally isolated from soil bacteria (bacillus & streptomyces) and fungi (penicillin and aspergillus) many are now semi-synthetic or totally synthetic.

Include: penicillins/ cephalosporins/ carbapenems/ aminoglycosides/ erythromycin: tetracyclines/ etc.

Question 14

Penicillins

Answer 14

Over 10,000 derivatives it 12 are used today

Treats syphilis, gonorrhea, staph and strep

Action: prevents cell wall synthesis by blocking peptidal bridges from forming between AA chains of muramic acid molecules on different levels of the peptidoglycan cell wall (static)

Question 15

Ampicillin

Answer 15

Acid-resistant, can be taken orally

Question 16

Methicillin

Answer 16

Used primarily on penicillin resistant strains, but now there are methicillin resistant strains (MRSA)

Question 17

Amoxicillin

Answer 17

Amoxicillin used to give orally in children. Broad spectrum which produces elevated blood levels of the antibiotic.

Known as augmentin

Question 18

Why are some bacteria resistant to penicillins?

Answer 18

And enzyme Beta Lactamase (composed of b-Lactamase and penicillinase) which destroys the beta Lactam ring in penicillins and cephalosporins.

Clavulanic acid in a noncompetitive inhibitor of penicillinase and is incorporated in some semisynthetics to treat penicillin resistant strains

Monobactams are single ringed variants of penicillin, lacking the pentagonal loop located beside beta Lactam ring

Question 19

Cephalosporins

Answer 19

First isolated in 1948 and are structurally simar to penicillins (same action and a beta Lactam ring in structure)

Cefazolin/ moxalactam/ cephalothin/ cefotaxime

Question 20

Carbapenems

Answer 20

Class of very broad spectrum antibiotics

Question 21

Aminoglycosides

Answer 21

Group of antibiotics with amino sugars and an aminocylitol ring. Usually in in mycin or Micin.

Action: binds to 30s ribosomal subunit, interfering with protein synthesis. Streptomycin was first antibiotic used to tx TB. Side effects of these meds are kidney damage and tinnitus

Neomycin/ amikacin/ gentamycin

Question 22

Erythromycin

Answer 22

Member of macropods group of antibiotics, effective against gram pos bacteria. Generally bacteriostatic and readily absorbed after oral administration. Used in persons sensitive to penicillins. Antimicrobic of choice for walking pneumonia, legionaires disease and dysentery/diptheria

May cause mild liver injury

Question 23

Tetracyclines

Answer 23

Consist of four fused rings first isolated in 1947. Usually semi-synthetic.
Action: broad spectrum, bind to 50s ribosomal subunits or to charge tRNAs preventing attachment to acceptor sit on mRNA ribosome complex( interferes with translation) because they bind to charge tRNAs, products with a lot of magnesium (antacids)are not recommended with Tetracycline use. Prolonged therapy can result in skin sensitivity to light.

Achromycin/ aureomycin/ terramycin/doxycycline

Question 24

Chloramphenicol

Answer 24

Action: broad spectrum affects protein synthesis

May cause aplastic anemia and is drug of choice for typhoid fever and certain types of meningitis.

Question 25

Polypeptides

Answer 25

Bacitracin - used topically against staph skin infections (impetigo) affects cell wall synthesis Polemic in B - affects cell membranes by distortion. Used topically These two + neosporin comprise triple antibiotic ointment

Question 26

Quinolone a and floroquinolones

Answer 26

First quinolone was naldixic acid (negram) and was used to treat UTIs and kidney infections. Action: work by inhibiting the enzyme helicase. Often prevent DNA molecules from separating and leads to rapid cellular death Norfloxacin& cipro

Question 27

Antimyobacterials

Answer 27

Used in to of mycobacterium TB. INH- competitive inhibitor- affects vitamin B6 Rifampin- interferes with RNA synthesis and may cause liver damage. "Red man syndrome" Ethambutol - RNA synthesis- used in primary tx Paraminosalicyclic acid- often used in combo with ^^

Question 28

Vancomycin

Answer 28

Action: inhibits peptidoglycan synthesis and used against penicillinase producing staph that cause life threatening diseases. (Now some resistance and are untreatable)