LAB EXAM #1 Flashcards
Paul Ehrlich:
Discovered chemotherapy and magic bullets- salvarsan to treat syphilis
Alexander Fleming:
Discovered abx- penicillin
Gerhard Domagk:
Discovered sulfanilamide- 1st practical antimicrobial
2 chemotherapeutic/antimicrobial agents:
Antibiotics- used as medicine against bacteria, protozoans, fungi
Antibacterials- soaps, disinfectants
How is an antimicrobial more toxic to pathogens than humans?
- Differences in structure or metabolism
- Different metabolic pathways in bacteria compared to human cells
- Protozoa, fungi, and worms are more similar to humans so they are more difficult to cure
Broad spectrum antibiotic:
Works against many types and good when the bug is unknown
Narrow spectrum antibiotic:
Good against a small number of germs and good when the bug is known
3 side effects to antibiotics:
- Toxicity
- Allergies
- Disruption of normal flora
Toxicity effect to abx:
-Possible damage to organs, kidney, liver, teeth
Allergic effect to abx:
Anaphylactic shock
Disruption of normal flora effect to abx:
Superinfections- commensals killed, replacement flora moves in
6 mechanisms of action:
Acronym
- Inhibition of cell wall synthesis
- Disruption of cell membranes
- Inhibition of protein synthesis
- Inhibition of nucleic acid synthesis
- Inhibition of metabolic pathways
- Inhibition of host recognition and attachment `
Inhibition of cell wall synthesis:
- Selective against some bacteria and fungi
- B-lactam ring
Disruption of cell membranes:
- Selective against some bacteria and fungi
- Binds phospholipids
Inhibition of protein synthesis: (abx that inhibit protein synthesis)
- Aminoglycosides
- Tetracyclines
- Macrolides
Inhibition of nucleus acid synthesis:
A.) Blocks DNA replication or prevents transcription to RNA, toxic to host
B.) Nucleotide analogs- non-functional molecules similar to A, T, C, G, or DNA
Inhibition of metabolic pathways:
A. Competitive inhibition of enzymes- Sulfanilamides
B. Molecular mimicry
Inhibition of host recognition and attachment:
Attachment antagonists
B-lactam ring:
Disrupts enzymes needed to cross-link peptidoglycans
2 ways microbes develop resistance:
- Chromosomal genes
2. Extra-chromosomal genes- plasmids
5 mechanisms of resistance:
- Producing new enzymes that deactivate abx
- Altering the cell membrane to prevent drug entry
- Altering drug’s target to prevent binding
- Altering cell’s metabolic pathways
- Pumping drug out of the cell
Disinfection:
Reduce number of microbes to safe levels
Sterilization:
Removal of all microbes on an object
Disinfectants:
Agents applied to inanimate objects
Antiseptics:
Kills microbes on external surface of living tissue
Sanitizer:
- Disinfects food equipment and utensils
- Can be soap and water
Effectiveness of chemical agents is influenced by: (6)
- Time
- Temp
- pH
- Concentration
- Number of organisms
- Types of organisms
Time effectiveness in chemical agents:
Length of exposure
Bacteriostatic agent:
Inhibits growth of microbes, but doesn’t kill them
5 ways to limit drug resistance:
- Patient must finish rx- stopping early lets resistant strains multiply
- Synergism: additive effect of 2 different drugs
- penicillin damages wall, lets streptomycin enter more easily - Use drugs for serious cases only
- Continue to develop second or third generation semisynthetic drugs
- Limit antimicrobial use in farm animals
Temp effectiveness in chemical agents:
Increased temp= faster death rate, doubles with every 10 C increase
pH effectiveness in chemical agents:
Affects ability to penetrate the cell
Concentration effectiveness in chemical agents:
High= bacteriocidal Low= bacteriostatic
Types of organisms effectiveness in chemical agents: (4)
A. Species variability
B. Growth phase variability
C. Most susceptible period
D. Endospores
2 mechanisms of action of chemical agents attacking cell component:
- Protein denaturation
2. Membrane sufactants
Bacteriocide:
Kills bacteria specifically, not spores or fungi
Protein denaturation:
- Hydrogen and disulfide bonds disrupted
- Shape altered
- Function lost
- Ex: Alcohol, acids, strong bases, halogens, heavy metals
Membrane surfactants:
Dissolve lipids, alcohols, detergents
Germacide, microbicide:
Kills germs in general
Host microbe interactions
Symbiosis: (3)
- Mutualism
- Commensalism
- Parasitism
Host microbe interactions
Normal (indigenous microflora): (3)
- Resident flora
- Transient flora
- Opportunists
Viricide:
Agent inactivates viruses
Fungacide:
Agent that kills fungi
Sporocide:
Agent that kills bacterial or fungal spores
Host microbe interactions
Contamination, infection, disease: (5)
- Colonization
- Contamination
- Infection
- Infestation
- Disease
Resident flora:
Microbes that are always present, mouth, nose, throat, intestines
Transient flora:
Occur under certain temporary conditions, may last hours or months
Opportunists:
Residents that can cause disease under some conditions:
A. transfer of normal flora to unusual body site
B. disruption of normal flora
C. immunocompromised- failure of normal immune system
Colonization:
Microbes appear and grow on surfaces, skin, and mucous membranes
Contamination:
Unwanted microbes are present, inanimate objects, media, skin surface
Infection:
Invasion, multiplication of microbes in or on host
Infestation:
Multiplication of arthropods or worms
Disease:
Infection leads to disruption of normal functioning- diminished health
