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107 Cards in this Set
- Front
- Back
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chemotherapeutic agents
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chemicals that interfere directly with the proliferation of microorganisms, at concentrations that are tolerated by the host
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bacteriostatic drug
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inhibition of growth reversed when the drug removed
immune system must still kill the microbe |
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bactericidal drug
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exerts irreversible, lethal effect
Dead bugs don't mutate won't develop resistance |
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antiseptic
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opposes sepsis or putrefaction
applied to living tissues |
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disinfectant
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prevents infection
applied to inanimate objects |
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sanitization
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reduces numbers of bacteria to acceptable standards
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sterilization
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complete destruction of all forms of life
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what type of control method for microorganisms will kill endospores?
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Autoclave
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will endospores survive pasteurization?
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YES
it disinfects and kills milk-borne pathogens and vegetable forms but not endospores |
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does radiation have good or bad penetrating power for killing microbes?
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Poor penetrating power
works well on surfaces such as desk and hoods |
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True or False
antibiotics are filter sterilized |
True
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Provide examples of strong oxidizing agents
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Halogens
Iodine Chlorine Bromine Fluoride |
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provide examples of acylating agents
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Formaldehyde: toxins, surfaces
Glutaraldehyde: less toxic than formalin Ethylene oxide: heat sensitive objects |
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what is the most effective concentration of alcohol on microbes (not humans)?
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70-90% Isopropyl alcohol
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why does hydrogen peroxide kill anaerobes?
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bacteria do not have catalase to break it down
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what are zinc salts used for?
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topical and antifugal treatment
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what is the site of lysozyme attack for antibiotics in a gram positive cell wall?
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NAG-NAM linkage in b-1,4
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what is a NAM that is present in the cell wall of a Gram + bacteria?
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Muramic acid which is a NAG with lactic acid esterified in C3
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how is a cell wall produced by a Gram + bacteria?
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Transglycolase
Transpeptidase Carboxylase Racemase FEM proteins |
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what is responsible for the cross linking in the cell wall of gram + bacteria
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Pentaglycine or tetra/pentapeptide
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what is the role of D-amino acid racemase in the cross linking formation?
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to recycle the D-Ala after the petapeptide and tetrapeptide have been linked
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how does cycloserine play a role as an antimicrobial?
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inhibits reactions involved in incorporation of alanine into cell wall precursor
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what is the function of the bacitracin antimicrobial?
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prevents dephosphorylation of phospholipid carrier which prevents regeneration of carrier necessary for synthesis of the cell wall to continue
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what is the function of the glycopeptides as a antimicrobial?
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bind to terminal end of D-ala-D-ala residues and prevents incorporation of subunit into growing peptidoglycan
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how do beta-lactams inhibits the cell wall synthesis of bacteria?
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bind to and inhibit enzymes which catalyze the link which attaches the new wall unit to the growing peptidoglycan
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what are the different mechanisms of action that an antimicrobial can have?
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inhibit protein synthesis
inhibit DNA or RNA synthesis Inhibit folate synthesis Inhibit cell wall synthesis |
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what are the properties of an ideal chemotherapeutic agent?
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antimicrobial properties:
selectivity for microbial rather than mammalian targets Cidal activity slow emergence of resistance Narrow spectrum of activity |
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what are the pharmcological properties of an ideal chemotherapeutic agent?
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Non-toxic to the host
Long plasma half life Good tissue distribution including CSF Low plasma protein binding Oral and parenteral dosing forms No interference with other drugs |
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what is the mechanism of action for BETA LACTAMS?
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this antibiotic with 4-membrane Beta lactam ring sterically resembles mucopeptide biosynthesis intermediate
1. acts by binding to enzymes involved in final process of cell wall synthesis -inhibits polymerization and attachment of new peptidoglycan to cell wall 2. Penicillin binding proteins |
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what is the mechanism of action for Penicillin family of antimicrobials?
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steric similarities of penicillin and D-ala-D-ala end of peptidoglycan
1. blocks cross linking of pentaglycyl bridge 2. leads to weakend mucopeptide and cellular lysis spheroblast > protoplast > cytolysis 3. requires growing cells in order to be expressed DONT USE WITH BACTERIOSTATIC DRUGS 4. |
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Is penicillin more effective in gram + or gram - bacteria?
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generally more effective in gram + bacteria
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True or False
Penicillins are bacteriacidal |
True
they kill the bacteria |
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what is the penicillin binding protein?
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transpeptidases
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what must the beta-lactam penicillin do to be effective
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1. penetrate the cell layers
2. keep its beta-lactam ring intact 3. Bind to the transpeptidase |
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how do gram negative bacteria defend themselves from penecillin?
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altering their porins
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how do gram negative and gram positive bacteria defend themselves against penecillin?
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Beta lactamase enzymes that cleave the C-N bond in the beta-lactame ring
Alter structure of transpeptidase |
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True or False
with each new generation of cephalosporins the drugs are able to kill an increasing spectrum of gram negative bacteria |
True
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Do patients that have an allergy to penicillin have an allergy to 3rd generation cephalosporins?
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10% of patients do
Same allergic reaction occurs IgE mediated reaction or more common a rash appearing weeks later |
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what are 3rd generation cephalosporins used to treat?
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multi-drug resistant aerobic gram negative organisms that cause hospital acquired pneumonia, meningitis, sepsis, or urinary tract infection
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what are Monobactams used to treat?
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narrow spectrum limited to aerobic gram negative bacteria
may be combined with other antibiotics |
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what is the mechanism of action for penicillin, cephalosporin, monobactams, carbopenems, and beta-lactamase inhibitors?
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blockage of cross linking of the pentaglycyl bridge in the cell envelope
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what are clavulanate and sulbactam used for?
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these drugs must be used in combination with other drugs.
they are beta lactams such as methicillin 1. used in with penicllin to protect beta lactamase and keep effective antibiotic |
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why is staphylococcus aureus resistant to penicillin?
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it produces a penicillinase
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what is the point in giving a beta latamase inhibitor with a penicillin?
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these enzymes are inhibitors of beta lactamase and are given in combination with penicllins to create a beta lactamase resistant combination
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what is the mechanism of action of Vancomycin?
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blocks cross linking of peptidoglycan pentapeptides by binding to D-ala-Dala end
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what is Vancomycin used to treat infections of?
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used to treat infections with methicillin and cephalosporin resistant Staphylcoccus (MRSA)
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what is the drug of last resort for resistant strains of bacteria?
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Vancomyocin and Teicoplanin
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why does the treatment with vancomyocin require hospitalization?
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painful and toxic
kidney failure is possible treatment must be long term for it to be effective |
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what type of bacterial infection is Vancomyocin used to treat?
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gram positive cocci resistant strains such as MRSA
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why are agents affecting the cell membrane permeability such as polymyxins generally more toxic to humans?
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due to nonspecific mechanism of action
they are used to treat Gram Negatives |
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what is the mechanism of action for Polymyxin B?
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passes through the outer cell membrane of gram negatives dissolves the cytoplasmic membrane (phospholipids)
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what is the mechanism of action of Polymyxin B?
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passes through the outer membrane of gram negatives dissolves cytoplasmic membrane
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where does polymyxin b pass through? what could this be a concern for?
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passe through the kidneys, not the CSF
patients with parenteral treatment must be in the hospital due to renal involvement |
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what type of infection is Polymyxin B used to treat?
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Pseudomonas, and other gram negative bacteria nonrefractive to other drugs
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how many antimicrobials are there that inhibit protein synthesis?
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8
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what are the 8 antimicrobials that inhibit protein synthesis?
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(CLeAn TOMS)
C: Chloramphenicol & Clindamycin L: Lincomyocin e A: Aminoglycosides n T: tetracylcines O: oxazolidinones M: macrolides S: streptogramins |
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which drugs bind to the 50S ribosome to inhibit protein synthesis?
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Chloramphenicol
Clindamycin Lincomyocin Steptogramins |
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Which drugs bind to the 30S ribosome to inhibit protein synthesis?
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Aminoglycosides
Tetracyclines |
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what is the mechanism of action of macrolids?
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blocks protein synthesis
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what is the mechanism of action for Oxazolidinsones?
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inhibits the A & P sites
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what is the mechanism of action for Tetracylcine?
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bind to 30S ribosome
blocks tRNA access prevents translation |
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when tetracycline is administered to a patient is the antimicrobial going to kill the bacteria or is the eradication of the microbial dependent on the immune system?
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Tetracycline is bacteriostatic
it will keep the bacteria from growing and multiplying Eradication is dependent on the immune system |
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what is a macrolide?
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an antimicrobial that has a basic structure of Erythromyocin but modified to from the macrolides such as Azithromyocin and Clarithromycin
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Azithromyocin and Clarithromyocin are examples of what type of antimicrobial?
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Macrolides
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what do macrolides bind to in order to stop protein synthesis?
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50S ribosomes subunit blocking macromolecule synthesis
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what type of bacteria is macrolides useful against?
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Gram positive >>>> Gram Negative
Intracellular bacteria: Chlamydia Mycoplasma |
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Is Spectinomycoin bacteriocidal or bacteriostatic?
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bacteriacidal
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What is used specifically for the treatment of gonorrhea?
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Spectinomycin
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Is Spectinomyocin effective for treatment of syhphillis?
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NO
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what is the mechanism of action for Spectinomycin?
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binds to 30S ribosome subunit
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what is the mechanism of action for Clindamycin/Lincomycin?
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blocks protein synthesis bpy binding to 50S ribosome subunit
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what was the first commercially synthesized antibiotic?
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Chloramphenicol
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what is the mechanism of action of Chloramphenicol?
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binds to 50S subunit to prevent translation by blocking protein bond formation
this also effects mammalian ribosomes |
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What is Chloramphenicol used to treat?
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SEVERE DISEASES
because it can cause hypersenstivity, acts on mammalian cells and 1/40,000 causes bone marrow aplasia |
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Give examples of an Aminoglycodside antibiotic?
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Gentamicin
Streptomycin Tobramycin |
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what is the mechanism of action for Streptomycin?
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bind to 30S ribosome subunit to give misreading leading to missense or nonsense proteins
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what is the mechanism of action for Oxazolidinone?
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inhibits A and P sites in protein synthesis
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What would you use Oxazolidinone to treat?
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used almost exclusively against resistant gram POSITIVE cocci such as VRE to prevent development of resistance
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what is the mechanism of action of Streptogramins?
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binds to 50S ribosome subunit
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Is Clindamycin affected against anaerobic microbes?
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YES
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What would a surgeon use as an antibiotic for a penetrating would such as a knife or bullet wound?
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Clindamycin along with an amingoglycoside
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why is clindamyocin with an aminoglycoside used to treat a penetrating would to the abdomen?
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when the GI tract is perforated it releases its contents of gram negative and anaerobic bugs into the peritoneal cavity. The aminoglycosides take care of the aerobic gram negatives and clindamycin takes care of the anaerobes
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what is used to treat pseudomembranous colitis caused by Clostridium difficile?
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Vancomyocin and Metronidazole
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what are some side effects of streptomycin?
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CN VIII toxicity which can cause vertigo and hearing loss
hearing loss is usually irreversible |
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Can Spectinomycin be used to treat Gohnorrheoea that is resistant to penicillin and tetracylcine?
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YES
caused by Nisseria gonorrheoeae |
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what is the mechanism of action of a sulfonamide?
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Bacteriostatic
competitive antagonist of PABA which leads to folic acid |
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what step in folic acid synthesis do sulfonamides interfere?
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it acts as the enzyme would to convert PABA into dihydropteroc acid
instead with a sulfonamide present the bacteria runs out of folic acid |
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what type of drug is Trimethoprim?
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sulfa-like drug used alone or with sulfamethoxazole
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what is the mechanism of action of Trimethoprim?
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highly selective for dihydrofolate reductase of microbes
It inhibits folic acid synthesis used in treatment of urinary infection |
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what would be a common use for Trimethoprim?
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urinary infection
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what is the classification of a sulfonamide?
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antimetabolite
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what drugs are inhibitors of RNA/DNA synthesis?
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Quinolone
Rifampin Rifabutin Metronidazole |
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describe the mechanism of action of Quinolone.
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binds alpha subunit of DNA gyrase
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describe the mechanism of action of Rifampin/Rifabutin
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prevents transcription by binding DNA dependent RNA polymerase
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describe the mechanism of action of Metronidazole
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disrupts bacteria DNA
Is a cytotoxic compound |
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which antibiotic binds the alpha subunit of DNA gyrase?
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Quinoline
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what antibiotic prevents transcription by binding DNA dependent RNA polymerase
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Rifampin/Rifabutin
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what antibiotic disrupts bacteria DNA?
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Metronidazole
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what type of infection would you prescribe rifampin for?
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Mycobacterium
meningococcus |
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what type of bacteria does Quinolones act on?
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gram positive and gram negative
block DNA gyrase which is essential for DNA replication and repair |
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what type of infection would you prescribe Metronidazole?
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anaerobic infections
GI abscesses f |
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what antibiotic can be used as antibuse for alcoholics?
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Metronidazole
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what is found in Quinolone that makes it difficult for microbes to develop resistance?
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Ciproflaxin is an example of a Quinolone
Fluorine is present which makes metabolism in the microbe difficult |
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what antibiotics prevent polypeptide elongation at the 50S ribosome?
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Macrolide
Clindamycin Steptogramins |
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what antibiotic prevents initiation of protein synthesis at 50S ribosome?
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Oxazolidinone
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What antibiotic prevents polypeptide elongation at the 30S ribosome?
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Tetracycline
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what antibiotic produces premature release of aberrant peptide chains from 30S ribosome?
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Amingoglycoside
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