Ch. 20 - Microbiology

Term
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antimicrobial drugs are different from disinfectants in 2 ways because they must
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Terms in this set (50)
antimicrobial drugs are different from disinfectants in 2 ways because they must
must act within the host
selective toxicity
selective toxicity
kill harmful microbe with no damage to host
antibiotic
substance produced by a microbe that inhibits another microbe. term used for synthetic drugs as well.
many antibiotics are produced by
streptomyces bacteria
list order of classes in ability to kill (easiest to hardest
bacteria
protozoa
fungi
viruses
source of gram positive rod antibiotics
bacillus subtilis
paenibacillus polymyxa
actinomycetes are & what specifics are used for antibiotics?
filamentous bacteria that live in the soil
streptomyces, saccharopolyspora, micromonospora
fungi used for antibiotics
penicillum and cephalosporium
narrow spectrum antibiotics
penicillin G, isoniozid, ketbconazole, mefloquine, niclosamide, mefloquine, praziquantel, acyclavir
broad spectrum antibiotics
tetracycline and streptomycin
tetracycline targetsg+, g-, and chlamydias/rickettsiasstreptomycinmycobacteria and g- bacteriapencillin gnarrow spectrum antibiotic that targets g positive bacteriaketoconazolenarrow spectrum antibiotic that targets fungimefloquine (malaria)narrow spectrum antibiotic that targets protozoaisoniazidnarrow spectrum antibiotic that targets mycobacterianiclosamide (tapeworms) & praziquantel (flukes)narrow spectrum antibiotic that targets helminthsacyclovirnarrow spectrum antibiotic that targets virusesaction of antimicrobial drugsinhibit cell wall synthesis by targeting peptodiglycan inhibit protein synthesis by targeting trna/ribosomes inhibit nucleic acid replication and transcription injure plasma membrane by targeting lipids/sterols inhibition of synthesis of essential metabolitesinhibitors of cell wall synthesis can be either?natural or semisynthetic prevent peptodiglycan from cross linking sugars/peptides like NAG and NAM.natural cell wall synthesis inhibitorgram positive only like penicillin G extracted from penicillium disadvantages: susceptible to penicillinases like beta lactamases that cut and inactivate beta lactam ringsemisynthetic cell wall synthesis inhibitorstill have beta lactam ring side chains are changed some are broad spectrum which means they are effective against both g+ and g-.methicillinsemisynthetic cell wall synthesis inhibitor that is no used anymore due to bacterial resistance. MRSA - methacillin resistant caused by s. aureuscephalosporinsstructures that resemble penicillin several generations of drug target different bacteriapolypeptide antibiotics includebacitracin and vancomycinbacitracineffective against gram positive bacteria topical application only like neosporin name bacillus found on tracy's armvancomycintreats MRSA infections led to vancomysin resistant enterococci (VRE) which are G+ opportunistic pathogensinhibitors of protein synthesisaminoglycosides, tetracyclines, macrolidesaminoglycosidesstreptomycin: alternative drug for tuberculosis side effects of aminoglycosides: hearing problems/kidney damagetetracyclines4 rings broad spectrum antibiotic produced by streptomyces spp. side effects: GI problems, opportunistic infectionsmacrolibescontains macocyclic ring - erythromycin: effective against g+ bacteria that is an alternative to penicillin for those who are allergicinjury to plasma membrane byblockage of the synthesis of fatty acids which are part of the phospholipid structure. also can use polymyxin BBpolymyxininjure plasma membrane effective against g- bacteria combined with bacitracin and neomycin topical use only like neosporininhibitors of nucleic acid synthesisrifamycin and quinolones/fluroquinolonesrifamycinaka rifampin inhibit mRNA synthesis can easily penetrate tissues, but can't get to csf used against mycobacteria (tuberculosis/leprosy) side effect: orange urine, feces, or other bodily fluidsquinolones/fluoroquinolonesselectively inhibit enzyme required for DNA replication fluoroquinolones: relatively non toxic and used for UTIs, pneumonias. - ciprofloxacin (cipro): used for anthrax infectionsinhibitors of metabolitessulfa drugssulfa drugsbacteriostatic - inhibit growth competitive inhibitor for follic acid pathway paba is the normal substrate, but sulfa drug gets in way and enzyme cannot distinguish between twoantibiotic resistancethere may be few cells that are resistant to antibiotics susceptible cells die and resistant cells remainmechanisms of bacterial resistance to antibioticspreventing drug from reaching target site destruction/inactivation of drug altering the drugs target site (change rRNA sequence) rapid efflux: pumping of the drug out of the cellhow are pathogens able to carry out these mechanisms of resistance?random genetic mutation horizontal gene transferrandom genetic mutationmutation in DNA - new protein (enzyme) - new function mechanism of resistancehorizontal gene transfertransfer of DNA (genes) to other bacteria of same generation by means of conjugation (cell to cell exchange), transformation (free DNA taken up to bac. cell) , or transduction (phage transfer of bacterial DNA)vertical gene transfertransfer of dna to other bacteria in lower generation parent to childantibiotic misuseex. triclosan -purchased without prescription in less developed countries -does regimens are shorter than needed to remove all the pathogenic bacteria which encourages survival of resistant strains. -use of antibiotics to promote growth of animals for consumptionantimicrobial peptidesproduced by birds, amphibians, plants, and mammals steriods in liver of sharksnew approaches of antibioticsantisense agents, RNAi and small interfering RNAs (siRNAs), bacteriophagesantisense agentsnucleic acids that bind pathogen DNA or RNA sequences, block protein synthesisRNAi and small interfering RNAssiRNAs double stranded RNA that blocks protein synthesisbacteriophagesphage therapy