a chemical that treats a disease, especially by killing microorganisms
What organisms produce antibiotics?
most antibiotics are produced by Streptomyces a filamentous soil bacteria
What is the difference between a synthetic antimicrobial and an antibiotic?
Synthetic are partially made in a lab and antibiotics are natural.
Why are viruses, fungal and protozoan infections more difficult to treat than bacterial?
Because they are similar to our cells, Eukaryotic. They have membrane-bound organelles, etc.
What is a disadvantage of broad-spectrum antimicrobials?
Many will also kill off the normal microbiota which normally compete for "space" with pathogenic bacteria to limit their growth.
What is a narrow spectrum antimicrobial?
effective only against specific strains
What is a SUPERINFECTION?
if the normal microbiota population is disrupted this may cause the survivors to flourish, becoming opportunistic pathogens which equals a superinfection.
List the 5 mechanisms of antibiotic activity and examples of each.
1. Inhibit cell wall synthesis ex:Penicillin, Cephalosporins, Bacitracin, Vancomycin 2. Injure Plasma Membrane ex: Polymixin B 3. Inhibit DNA replication and translation ex: Quinolones, rifampin 4. Inhibit Enzymatic activity Ex: Sulfanilamide, trimethoprim 5. Inihit protein syntheses Ex: Erythromycin, tertacyclines, streptomycin
Explain how the disk-diffusion method of susceptibility works?
Petri dish is inoculated, drug impregnated filter paper discs placed on agar, as drug diffuses into agar the farther it moves the lower the concentration.
Does the largest zone of inhibition mean the best antibiotic?
yes, determines if it is sensitive, intermediate or resistant.
Explain the broth dilution test and the difference between MIC and MBC.
Minimal bactericidal concentration MBC allows for distinction between bacteriostatic and bacteriocidal. Minimal inhibitory concentration MIC is determined by a series of broths with decreasing concentration of the drug.
List 3 mechanisms that a resistant mutant may use to combat the effectiveness of an antibiotic.
Destruction or inactivation of the drug, prevention of penetration to target site in bacteria, alteration of the drug's target site or increased/decreased production of target molecule.
What is a nosocomial infection?
An infection that is the result of treatment in a hospital.
What mode of action does penicillin have? Is it effective against G+ or G-?
Inhibits cell wall synthesis. Only G positive bacteria.
What is Vancomycin?
a bacterial antiobiotic used against resistant strains of streptococcus and staphylococcus
What is Rifampin?
Used to treat Tuberculosis and leprocy. Can penetrate tissues, cerebrospinal fluid and abscesses. Side effects: orange urine, feces, saliva, sweat and tears
What are Tetracyclines?
Broad spectrum antibiotic. Treats ricketsias, chlamydias, syphilis, gonorrhea. Very commonly put in cattle feed.
What is Acyclovir?
Herpes virus. Interferes with viral DNA or RNA synthesis but doesn't interfere with host cell DNA synthesis.
How can bacteria become drug resistant?
Overuse, not completing round, unecessary use, long term use and people carrying resistant bacteria to other regions.
What does waste water consist of?
Household water, toilet waste, rainwater and industrial wastes.
How are microbes involved in the process of treating waste water?
Aerobic microbes oxidize the dissolved organic matter to carbon dioxide and water. Anaerobic bacteria, especially methane-producing bacteria decrease organic solids by degrading them to soluble substances and gases mostly methane and carbon dioxide.
What is BOD? Why do they use it in treating waste water?
Biochemical oxygen demand is a measure of the biologically degradable organic matter in water. BOD is determined by the amount of oxygen required by bacteria to metabolize organic matter
What is effluent? How can effluent be disinfected?
It is the water flowing out after the sludge is removed. Effluent can be disinfected by chlorination
What is pass-through in effluent?
It gets passed through a reverse osmosis purification system to remove microorganisms.
How is solid material entering the system dealt with? What product is made?
Large floating material is screened out, the sewage flows through settling chambers to remove sand and other gritty material, skimmers remove floating oil and grease. The product made is effluent.
How have we contributed to bacteria becoming drug resistant?
over use, not completing dosage, unnecessary use, long term use, antibiotics in animal feed.