Antibiotics, Antifungals & Antivirals

Question 1

antibiotics

Answer 1

a class of drugs that inhibit the growth of bacteria without harming the human host

Question 2

selective toxicity

Answer 2

important feature of antibiotics that enable them to target and kill bacteria without harming the infected host

Question 3

Alexander Fleming

Answer 3

1929 discovered PCN

Question 4

Gram-positive bacteria

Answer 4

those bacteria that create a positive result in the Gram stain test for bacteria

Question 5

Gram-negative bacteria

Answer 5

bacteria that give a negative result on the Gram stain for bacteria

Question 6

Bactericidal

Answer 6

• cidal = “to kill or have killing power”
• bactericidal antibiotics typically kill the bacteria it targets

Question 7

Bacteriostatic

Answer 7

• static = stopping or controlling
• bacteriostatic antibiotics stop bacteria growth and replication. The host’s immune system must complete the task of clearing the body of the invading bacterial species

Question 8

Antibiotic Mechanisms of Action

Answer 8

1. inhibit cell wall synthesis
2. inhibit protein synthesis
3. interfere with essential bacterial enzymes

Question 9

Antibiotic Classes

Answer 9

• ß-lactam
• Other cell-wall synthesis inhibitors (cell wall inhibitors that lack the beta-lactam ring)
• Protein-synthesis inhibitors
• Quinolone

Question 10

ß-lactam

Answer 10

works by inhibiting bacterial cell-wall synthesis by use of the beta-lactam ring molecular structure that interferes with the bacteria enzymes used to build its cell walls; ultimately killing the bacteria.

This class of antibiotics includes:

• PCN
• cephalosporins
• carbapenems
• monobactams

Question 11

ß-lactamase

Answer 11

enzymes bacteria have developed to become resistant to beta-lactam antibiotics. the lactamase reacts with the beta-lactam ring in the antibiotic, deactivating it = deactivating the antibitoic.

Question 12

Penicillinase

Answer 12

the specific beta-lactamase that dectivates PCN

Question 13

ß-lactamase inhibitor

Answer 13

one way around the inactivation of antibiotics is to give a beta-lactamase inhibitor such as:

• clavulanic acid
• sulbactam

which increase the effectiveness of the antibiotic

Question 14

Penicillins

Answer 14

• group of antibiotics derived from Penicillium fungi
• bactericidal
• natural PCN’s are made from the fungi or mold
• chemically modified PCN’s developed to improve resistance to beta-lactamases
• -cillin

Question 15

paresthesia

Answer 15

numbness and tingling

Question 16

unicaria

Answer 16

hives

Question 17

PCN Allergic Reactions

Answer 17

• itching
• paresthesia
• wheezing
• choking
• fever
• swelling
• generalized uticaria

Question 18

cephalosporins

Answer 18

• beta-lactams derived from cephalosporium fungi
• ceph- or cef-
• classified by their generation (1st, 2nd, 3rd, etc.)

Question 19

carbapenems

Answer 19

• -enem
• broad spectrum beta-lactam
• highly resistant to most beta-lactamases
• not very soluble an have poor oral bioavailability
• delivered via IV in hospital setting
• used for serious infections as an antibiotic of last resort

Question 20

Poor Oral Bioavailability

Answer 20

given in oral dosage, the medication is difficult to absorb into the body and become effective

Question 21

monobactams

Answer 21

• aztreonam is the only currently available drug in this class
• works against gram-negative bacteria
• highly resistant to beta-lactamases

Question 22

Other Antibiotic Cell-Wall Synthesis Inhibitors

(those lacking the ß-lactam ring)

Answer 22

• vancymycin
• bacitracin
• fosfomycin
• daptomycin

these medications work similar to the beta-lactam antibiotics, however these medications lack the ß-lactam ring.

additionaly, eacy one of these drugs is different in structure and mechanism of action against the bacterial cell wall

Question 23

protein-synthesis inhibitors

Answer 23

works by preventing protein synthesis in bacteria with selective toxicity

• three main categories

1. aminoglycosides
2. tetracyclines
3. macrolides

Question 24

aminoglycosides

Answer 24

• -mycin
• broad-spectrum antibiotics
• poorly absorbed from GI tract
• administered by IV or other parenteral means
• Important to note:
  
  • ototoxic
  • nephrotoxic
  • neuromuscular toxic
• small safety margin between toxic concentration and therapeutic effect

Question 25

tetracyclines

Answer 25

* -cycline * broad-spectrum antibiotics used for both gram-positive and gram-negative bacteria * can be given orally -- without food -- food impares absorption (exceptions are doxycycline and minocycline) * major side effects: * insoluble chelates - kind of calcium bond that discolors the teeth and inhibits bone growth * should not be used with children or pregnant women

Question 26

macrolides

Answer 26

* some end with -mycin * most end with -thromycin * can be given orally with relatively few side effects * useful in treating: * mycoplasma infections * pneumonia * Legionnaires disease * diptheria * pertussis

Question 27

quinolones

Answer 27

* relatively new class of antibiotics * work by inhibiting DNA synthesis * -oxacin * primarily used to treat UTIs * broad spectrum * used orally

Question 28

antifungals

Answer 28

used to treat fungal infetions; either superficial infections that effect the outer layers of skin, nails and hair -or- systemic fungal infections * fungal infections replicate more slowly making treatment problematic * these drugs are poorly soluble - making distribution to the site of infection problematic * as a result, antifungals typically work to assist the host's immune system in fighting against the infection * must have selective toxicity to be effective

Question 29

Antifungal Classes

Answer 29

* polyene antifungals * azole antifungals * echinocandins

Question 30

polyene antifungals

Answer 30

* polyene refers to the chemical structure that maks up this class * most popular is * amphotericin B * works by binding to sterols in the fungal cell membrane which disrupts membrane function causing leakage of electrolytes from the cell leading to cell death for the fungus * nephrotoxic * must be given by IV or topically

Question 31

azole antifungals

Answer 31

* azole = chemical structure of the class * work by inhibiting an enzyme fungi use to make sterol, leading to cell death * ergosterol

Question 32

echinocandins

Answer 32

* used to treat candida and aspergillus * inhibits fungi cell-wall production by targeting glucan * given by injection

Question 33

terbinafine

Answer 33

* an antifungal given for superficial infections * targets poorly vascularized tissues such as hair, skin and nails * administered topically

Question 34

Antivirals

Answer 34

* treat viral infections through the selective targeting of the viral-development cycle * vaccination is traditional method * a preventative strategy * selective toxicity

Question 35

antiviral chemotherapeutics

Answer 35

* developed as an additional fight against viral infections * successful in treating HIV, herpes, hepatitis B & C, and influenza A & B

Question 36

Anti-HIV

Answer 36

* drugs in this category work by a variety of mechanisms * multiple drugs, targeting different mechanisms, are given as a "cocktail" * targets an enzyme called *reverse transcriptase* * "cocktail" drugs are called RTIs - reverse transcriptase inhibitors * anti-HIV cocktails usually include one NNRTI and 2 NRTIs used in combinations * -ine

Question 37

RTI

Answer 37

* reverse transcriptase inhibitors * further divided into: * NRTIs - nucleotide reverse transcriptase inhibitors * NNRTIs - non-nucleotide reverse transcriptase inhibitors * -ine

Question 38

PI

Answer 38

* protease inhibitors * also anti-HIV * work by interfering with the processing of viral proteins, preventing the formation of new viral particles * -vir * used in combination: * 2 PIs + 2 NRTIs

Question 39

Influenza Drugs

Answer 39

* vaccination is standard approach * some antivirals have been developed that work as an alternative to vaccination * work by targeting the development cycle of of the flu virus and stopping its replication * oseltamivir (Tamiflu) * used for influenza A, administered within 48 hours of infection, shortens the duration of symptoms by 1/2