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23 Cards in this Set
- Front
- Back
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selective toxicity
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Kills harmful microorganisms without damaging the host
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Streptomyces
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More than half of our antibiotics are produced by this species
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abiosis
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the absence or lack of life; a nonviable state.
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Practically all antibiotic-producing microbes have some sort of ?
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sporulation process
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Broad-spectrum antibiotics
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Can result in overgrowth of Candida albicans and Clostridium difficile for instance
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Penicillins – β-lactams
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Group of over 50 chemically related antibiotics
Common core structure a beta-lactam ring Produced naturally or semisynthetically Prevent cross-linking of peptidoglycans |
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Natural penicillins
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Extracted from cultures of mold Penicillium
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Disadvantages of natural penicillins
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Susceptible to penicillinases – Beta-lactamases
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Penicillinase-resistant penicillins
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Methicillin was the first
MRSA methicillin resistant Staphylococcus aureus Now discontinued in the United States |
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MRSA
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is by definition a strain of Staphylococcus aureus that is resistant to a large group of antibiotics called the (beta lactams), which include the penicillins and the cephalosporins.
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Third generation cephalosporins
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Broad spectrum thus risk of opportunistic superinfections is high
Candida albicans Clostridium difficile |
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VRE
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vancomycin resistant enterococci
Very troublesome in hospital setting |
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Antimycobacterial antibiotics
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Mycobacterium cell wall
Mycolic acids; “acid-fast” Isoniazid (INH) – inhibits synthesis of mycolic acid (Mycobacterium tuberculosis) Ethambutol (EMB or E) – effective only against mycobacteria; inhibits incorporation of mycolic acids in cell wall; used in combination with other drugs to avoid resistance problems |
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Inhibitors of protein synthesis
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Aminoglycosides
Tetracyclines Choramphenicol Macrolides |
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Tetracycline problems
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Possible superinfections of Candida albicans
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Oxazolidinones
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Disrupt relationship of large and small ribosomal subunits;Linezolid (Zyvox)
Used mainly to combat MRSA |
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Injury to plasma membrane
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Triclosan (blocks fatty acid synthesis)
Platensimycin Polymyxin B, a polypeptide antibiotic Bacitracin, a polypeptide antibiotic |
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Inhibitors of nucleic acid synthesis
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Rifamycins (halt mRNA synthesis)
Quinolones (halt DNA synthesis) |
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Competitive inhibitors of the synthesis of essential metabolites
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Sulfa drugs
Silver sulfadiazine Topical burn treatment Sulfonamides Competitive inhibitor of an enzyme in folic acid synthesis Normal substrate para-aminobenzoic acid - PABA |
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95,000 people a year suffer from?
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drug resistant staph infections
85% of these infections were acquired in hospitals 19,000 people a year DIE from drug resistant staph infections |
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A drug resistant strain of
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Streptococcus pneumoniae is spreading
Persistent ear infections Rochester NY has a number of cases Is is also resistant to pneumococcal vaccine Resistant to 19 different antibiotics |
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Cyclic lipopeptides
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Also disrupt bacterial membranes
Loss of membrane potential Daptomycin (Cubicin) Approved 2003 Used against MRSA and VRE |
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BIG PROBLEM;Antibiotic production...
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not very profitable
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