ch 12

Question 1

1. Antibiotics are common metabolic products of …………………… …………….. ………
2. bacteria in what 2 genera?
3. molds in what 2 genera?
4. By inhibiting the other microbes in the same habitat, antibiotic producers have ….. competition for nutrients and space

Answer 1

1. aerobic bacteria and fungi
2. streptomyces and bacillus
3. penicillium and cephalosporium
4. less

Question 2

1. penecillium, cephalosporium, are what type of microbes?
2. Micromonospora, bacillus, and chromobacterium are what type of microbes?
3. what type of microbe is streptomyces?

Answer 2

1. molds
2. bacteria
3. filamentous bacteria

Question 3

1. what does “selectively toxic” mean when refering to antimicrobial drugs?
2. When are more side effects seen?

Answer 3

1. should kill or inhibit microbial cells without simultaneously damaging host tissues
2. As the characteristics of the infectious agent become more similar to the vertebrate host cell, complete selective toxicity becomes more difficult to achieve and more side effects are seen

Question 4

1. • 5. Name the five mechanisms of drug action:

Answer 4

1. cell wall inhibitors
2. cell membrane loss of selective permeability
3. DNA/RNA disruptors of replication and transcription
4. protein synthesis inhibitors (acting on ribosomes)
5. blockage and inhibition of metabolic pathways and products

Question 5

1. what is the spectrum of a drug?

Answer 5

1. range of activity of a drug
   Narrow-spectrum – effective on a small range of microbes
   Target a specific cell component that is found only in certain microbes (gram + or gram – cell ways)

Broad-spectrum – greatest range of activity
Target cell components common to most pathogens (ribosomes)

Question 6

1. which two antibiotics block synthesis of peptidoglycan (act on the cell wall)? What happens to cells when they encounter these antibiotics?
2. what type of cells are these most active on?
3. Can broad spectrum penicillins and cephalosporins cross the cell walls of gram-negative bacteria?
4. What family of antibiotics are penicillins and cephalosporins? What percentage of antibiotic drugs fall into this family?

Answer 6

1. penicillins and cephalosporins. Causes cell lysis
2. young, growing cells and more gram +
3. yes
4. beta-lactam >50% of all antibiotics are beta-lactam

Question 7

1. What do all penicillin relatives consist of?

2. Is it more or less economical to obtain natural penicillin through natural microbial fermentation

Answer 7

1. 3 structurally similar parts:
   Thiazolidine ring
   Beta-lactam ring
   Variable side chain dictating microbial activity
2. more economical

Question 8

1. Which antibiotic accounts for 1/3 of all antibiotic administered?
2. Are cephalosporins broad spectrum?
3. Are cephalosporins resistant to most penicillinases, and cause fewer allergic reactions
4. Generic names have root: – cef, ceph, or kef
5. How many generations exist? Is each group more effective against gram-negatives than the one before? Do they have improved dosing schedule and fewer side effects?
6. Which generation is most effective against gram-positive cocci and few gram-negatives?
7. Which generation is more effective against gram-negative bacteria?
8. Which generation is broad-spectrum activity against enteric bacteria with beta-lactamases
9. Whic generation has the widest range; both gram- negative and gram-positive?

Answer 8

1. cephalosporins
2. relatively
3. yes and yes
4. – cef, ceph, or kef
5. 4 generations. Yes. Yes. Yes.
6. 1st gen. cephalothin, cefazolin
7. 2nd gen. cefaclor, cefonacid
8. 3rd gen cephalexin, ceftriaxone
9. 4th gen cefepime

Question 9

1. Name 2 non-beta-lactam cell wall inhibitors:
2. Vancomycin is most effective at treating what types of infections and in what type of patient? Is it narrow spectrum?
3. What is Bacitracin?

Answer 9

1. Vancomycin and bacitracin
2. Staphylococcal infections in cases of penicillin and methicillin resistance or if patient is allergic to penicillin. Narrow spectrum
3. narrow-spectrum produced by a strain of Bacillus subtilis; used topically in ointment

Question 10

1. Name 3 drugs that have specificity for a particular microbial group, based on differences in types of lipids in their cell membranes:
2. How do polymyxins work?
3. How do Amphotericin B and nystatin work?

Answer 10

1. polymyxins, amphotericin and nystatin
2. interact with phospholipids and cause leakage, particularly in gram-negative bacteria
3. form complexes with sterols on fungal membranes which causes leakage

Question 11

1. Name 2 families of drugs that block protein synthesis:
2. Describe what aminoglycosides do:
3. How do tetracyclines work? Are they broad spectrum?
4. Name a few diseases treated by tetracyclines:
5. is tetracycline expensive? Does it have lots of side effects?
6. What is one dangerous drawback of drugs that interfere with protein synthesis?

Answer 11

1. Aminoglycosides and Tetracyclines
2. cause misreading of mRNA causing protein synthesis to be blocked streptomycin and gentamycin are examples)
3. Block protein synthesis by binding ribosomes (trna) Yes, broadspectrum
4. Treatment for STDs, Rocky Mountain spotted fever, Lyme disease, typhus, acne, and protozoa (eukaryotic parasites).
5. Generic tetracycline is low in cost but limited by its side effects
6. They cause mitochondrial damage in eukaryotes

Question 12

1. What is competitive inhibition?
2. What is the Synergistic effect?
3. What do sulfonamides and trimethoprim do (sulfa drugs)? Are these broad or narrow spectrum drugs?

Answer 12

1. drug competes with normal substrate for enzyme’s active site
2. the effects of a combination of antibiotics are greater than the sum of the effects of the individual antibiotics
3. block metabolic pathways by blocking the synthesis of folic acid by bacteria. Narrow spectrum

Question 13

1. How do drugs that affect nucleic acids work?

2. Name 2 such drugs and describe briefly:

Answer 13

1. May block synthesis of nucleotides, inhibit replication, or stop transcription

2. Chloroquine binds and cross-links the double helix to treat malaria infections and 
Quinolones inhibit DNA helicases
examples include: 
Cipro (Ciprofloxacin)
Levaquin (Levofloxacin)

Question 14

1. How do antiviral chemotherapeutic agents work?
2. What are drawbacks of these drugs?
3. what do protease inhibitors do?

Answer 14

1. Block penetration into host cell and Block replication, transcription, or translation of viral genetic material.
2. Selective toxicity is almost impossible due to obligate intracellular parasitic nature of viruses
3. block neuraminidase, a protease enzyme of the flu and HIV

Question 15

1. Name 4 drugs used to treat the flu:
2. Amantadine, rimantidine
   are restricted almost exclusively to which viral infections? How do they work?
3. Do Relenza and tamiflu – have a slightly broader spectrum? How do they work?
4. What does neuraminidase do?

Answer 15

1. Amantadine, rimantidine, and Relenza and tamiflu
2. influenza A, prevent fusion of virus with cell membrane
3. yes
4. blocks Neuraminidase in influenza A and B
5. Neuraminidase acts upon entry and exit during the viral replication

Question 16

1. What is the acyclovir family of drugs used to treat, and how does it function?
2. Name 2 drugs to treat HIV and AIDS:

Answer 16

1. they are antiherpes drugs. They terminate DNA replication in herpesviruses
2. Retrovirus and Azidothymidine (AZT) - first drug for treatment of aids.

Question 17

1. What are interferons?

2. What are some benefits of interferons?

Answer 17

1. Human-based glycoprotein produced primarily by second line of immune defense:
   Made by: fibroblasts and leukocytes
2. Reduces healing time and complications of infections,
   inhibits symptoms of cold and papillomavirus
   Slows the progress of cancers, leukemias, and lymphomas, and Treatment of hepatitis C, genital warts, Kaposi’s sarcoma

Question 18

1. What are Ketolides- telitromycin (Ketek)?
2. What are they used to treat, and what are they most effective against?
3. What are Oxazolidinones – Linezolid (Zyvox)?
4. What are they used to treat?

Answer 18

1. New class of antimicrobial with different ring structure from Erythromycin;
2. for infection when resistant to macrolides. Most effective against gram + respiratory tract infections
3. new class of synthetic antimicrobial that blocks the interaction of mRNA and ribosome (broad spectrum)
4. respiratory infections, skin and blood, (MRSA), and
   Vancomycin resistant Enterococcus (VRE)

Question 19

1. Estimate that …..% of all persons taking antimicrobials will experience a serious adverse reaction to the drug – side effects
2. What are considered major side effects?
3. What is a super infection?

Answer 19

1. 5%
2. Direct damage to tissue due to toxicity of drug,
   Allergic reactions,
   Disruption in the balance of normal flora- superinfections possible
3. When a pathogen is controlled by other microbes, but those good microbes get killed by antibiotics and the pathogen overgrows.