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1


Asepsis vs sepsis

 

 

 

Aseptic Surgical Technique

asepsis: absence of significant contamination

sepsis: microbial contamination

 

 

 

Prevents Microbial contamination in wounds

2

Sterilization

 

Commerical sterilization

 

Disinfection

 

Antisepsis

Removal of all microbial life

 

Kills C. Botulinum endospores

 

removal of pathogen

 

removal of pathogens from living tissue

3

Degerming

 

Sanitization

 

Biocide/Germicide

 

Bacteriostasis

Removal of microbes from a limited area

 

Lowering the number of micrbial counts on eating utensils

 

Kills microbes

 

Inhibits microbes (does not kill)

4


Microbial control Agent

Alters membrane permeability

 

damages proteins

 

damages nucleic acids

 

5

Heat

 

Moist heat sterilization

Kills by denaturing enzymes and altering structures

 

Denatures proteins (autoclave:  121C for 15psi)

6

Pasteurization

Reduces spoilage organisms & pathogens
Except:  Thermoduric organisms

 

 

7


Hepa vs membrane filtration


Hepa removes microbes >0.3um

 

Membrane filtration removes microbes >0.22um

 

8


Radiation

 

Ionizing

Nonionizing

Microwaves


Ionizing radiation:  x-ray, gamma rays & electron beams

  • Damages DNA
  • Ionizes water to release OH

Nonionizing radiation:  (UV, 260nm)

  • Damges DNA

Microwaves: kills by heat but not really antimicrobial

 

9

Phenol & Phenolics

(Carbolic Acid)

 

 

Disinfectant

Disrupts plasma membranes

10


Halogens

Iodine


Alters protein synthesis & membrane

Iodine

11


Halogen

Chlorine


Oxidizing agents

Bleach

12


Alcohol

Ethanol & Isopropanol


Denatures proteins & dissolves lipids

Needs water

13


Heavy Metals

Ag, Hu, Cu


Ag:  Silver nitrate

Hg:  Silver sulfadiazine (topical cream on burns)

Cu:  Copper sulfate, an algicide

14


Oligodynamic action


Denatures proteins

15

Denatures proteins

 

Denatures enzymes

 

Damages DNA

 

Disrupt plasma membranes

 

Alters Protein synthesis/membrane

Denatures proteins

  • Oligodynamic action (Heavy Metals)
  • Most heat
  • Alcohol (Ethanol, Isopropanol)

 

Denatures enzymes

  • Heat

 

Damages DNA

  • Radiation (Ionizing & nonionizing)

 

Disrupt plasma membranes

  • Disinfectant (Phenols & Phenolics)

 

Alters Protein synthesis/membrane

  • Halogen (Iodine & Chlorine)

 

16


Alexander Fleming


Penicillium notatum

17


Chemotheraphy

 

Antimicrobial Drugs

 

Antibiotic

 

Selctive Toxicity


drug used to treat a disease

 

Interferes with microbial growth inside a host

 

Inhibits a microbe using small amount of substance produced by another microbe

 

Kills harmful microbes without damaging host

18


Antimicrobial spectrum

Broad spectrum - wide range (Gram - & Gram +)

 

Narrow spectrum - Limited range

 

Superinfection - Pathogen that has develped resistance to an antimicrobial drug

 

19


Bactericidal vs Bacteriostatic


Bactericidal kills microbes

 

Bacteriostatic inhibits micrbial grown

20


Antimicrobial Drug Actions

1) Inhibits cell wall synthesis

  • Penicillion
  • Bacitracin
  • Vancomycin
  • Cephalosporins

2) Inhibits protein synthesis

  • Chloramphenicol
  • Erthromycin
  • Tetracyclines
  • Streptomycin

3) Inhibits Nucleic Acid replication & Transcription

  • Quinolones
  • Rifampin

4) Injurty to plasma membrane

  • Polymyxin B

5) Inhibits synthesis of essential metabolites

  • Sulfanilamide
  • Trimethoprim

 

 

21


Antibiotic Drug Actions


Inhibits Protein synthesis

 

Chloramphenicol:  Inhibits formation of peptide bond (50s)

Streptomycin:  Changes shape of 30s and reads mRNA code incorrectly

 

Tetracycline:  Interferes with tRNA & mRNA attachment - ribosme complex

22


Penicillin

Prevents cross linking of peptidogycan (mostly Gram +)

 

Natural

Semisynthetic

Extended spectrum

 

Penicillin G (requires injection)

Penicillin V (requires Oral)

B-Lactam Ring:  Common nucleus

 

23


Cell Wall synthesis inhibitors


Antimycobacterial antibiotics

  • Isoniazid (INH):  inhibits mycolic acid synthesis

 

Ethambutol

  • Inhibits incorporation mycolic acid

24


Protein synthesis inhibitors


Aminoglycosides

  • Changes 30s subunit shape (Broad spectrum)
  • Streptomycin
  • Neomycin
  • Gentamyci

 

25


Competitive Inhibitors

Sulfonamides

  • Inhibits Folic acid synthesis
  • Broad Spectrum

 

Action of Enzymes inhibited

 

26


Antiviral Drugs


Protease inhibitor

  • Indinavir (HIV)

 

Integrase Inhibitor: (HIV)

 

Attachment inhibition

  • Zanamivir (Influenza)
  • Block CCR5 (HIV)

 

Uncoating inhibition

  • Amatadine (Influenza)

27


Antibiotic Resistance


1) Blocks entry

2) Inactivates enzymes

3) Alters target molecule

4) Ejects antibiotic

28

Pathogenicity

 

Virulence

 

Portals of Entry

Ability to cause disease

 

Extent or degree of pathogenicity

 

MM, Skin, Parenteral route

29


Portals of Entry


MM

  • Respiratory Tract: measles & Small pox
  • GI Tract: Hep A, Poliomyelitis, Typhoid fever, Amoebic dysentery, Cholera
  • Genitourinary Tract: HIV, warts, herpes
  • Conjunctiva: Trachoma

30

Dose Dependent Onset


ID 50  (Infectious Dose) - causes disease in 50% of pop.

LD 50  (Lethal Dose) - Lethal dose in 50% of pop.