Fundamentals of Microbiology
Fundamentals of Microbiology MMG 201
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This 9 page Class Notes was uploaded by Reed McGlynn on Saturday September 19, 2015. The Class Notes belongs to MMG 201 at Michigan State University taught by Julius Jackson in Fall. Since its upload, it has received 90 views. For similar materials see /class/207346/mmg-201-michigan-state-university in Microbiology at Michigan State University.
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Date Created: 09/19/15
Chapter 11 Controlling microorganisms Decontamination l j 5 chemical agents or mechanical removal methods Primary targets Highest resistance heat120 radiation4000 grays sterilizing gas1200 mgl sporicidal liquid3 hr prions bacterial endospores 18x more resistant Moderate resistance LL39 I I I39 II I sp ium I aureus protozoan cysts other protozoan cysts fungal sexual spores zygospores naked viruses hep B amp polio Least resistance heat80 radiation1000 grays sterilizing gas700 mgl sporicidal liquid10 min most bacterial vegetative cells fungal spores amp hyphae yeast enveloped viruses protozoan trophozoites Types of Control Sterilization process that destroysremoves all viable microbes including the most resistant viruses amp endospores Disinfection destroys vegetative pathogens inanimate objects not endospores Sanitization removes mechanically microbes inanimate objects Antiseptic destroys disinfectants applied directly to exposed body surfaces Degermenation removes microorganisms from living tissue animate objects Microbial Death permanent loss of reproductive capability Factors affecting death rate and nature of microbes temp pH concentration or dosage of agent mode of action of agent presence of solventsorganic matterinhibitors salivafecesblood can inhibit disinfectants amp even of heat Celular targets physical amp chemical agents cell wall becomes fragile amp lyses antimicrobial drugsdetergentsalcohol cell membrane detergent surfactants proteins alcohols phenols acids heat protein amp nucleic acid synthesis stops replication transcription translation peptide bond formation or protein synthesis by chloramphenicol UV radiation formaldehyde microbicidal TDT thermal death time shortest length of time required to kill microbes at specified temp Clostridium botulism spores in canned green beans need combination of time amp temp that will kill all spores but not mush green beans 121 degrees for 30 min Bacteria range from Neisseria gonorrhoeae 50 degrees for 3 min to Staphylococcus Aureus 60 degrees for 60 min TDP thermal death point lowest temp required to kill microbes in 10 min A Moist heat low temps shorter exposure time max15min coagulation amp denaturation of proteins autoclave most effective 15 psi 121 degrees time varies denaturation of proteins desctuction of membranes amp DNA intermittent sterilizationtyndallization for substances that can t withstand high temps of autoclave put in this chamber for 3060 min then incubated for 24 hrs then steamed etc for 3 days canned foods amp laboratory media sera eggs disinfectant disinfectant spores technique which heat applied to liquids to kill microbes without changing avorfood values flash method 716 for 15 sec or batch method 6366 for 30 min NOT sterilization doesn t kill spores or many nonpathogenic bacteria B Dry heat higher temperatures lncineration flameelectric heating coil reduces microbes Dry 0ven150180 coagulate proteins microbiostatic slows growth by refrigeration 015 degrees or freezing lt30 degrees used to preserve food media amp cultures gradual removal of water from cells so cells can t metabolize lyophilization freeze drying preservation ionizing radiation bold penetrating power causes electrons to leave their orbits amp break DNA gamma xray cathode ray cold sterilization STERLZE medical supplies amp foods nonionizing radiation little penetrating power must be directly exposed from UV light causing pyrimidine dimmers interfere with replication mechanical removal methods ltration used to STERILIZE heat sensitive liquids amp air hospital isolation units amp industrial clean rooms chemical agents disinfectants sterilants preservatives degermers antiseptics Good Qualities fast amp low dosage solubility in water amp alcohol affordable penetrating broad spectrum 84 low toxicity noncorrosive amp nonstaining Levels ofChemical Decontamination Highlevel kill endospores may be sterilanls good for devices that go in body ntermediate level kill fungal spores tubercle bacillus 8L virus good for devices that touch mucous membranes Lowleve vegetative bacteria amp fungal cells some viruses good for devices that touch skin not mucous membranes Factors nature of material being treated degree of contamination time of exposure strength amp chemical action of germicide Germicida Categories 1 Halogens 2 Phenolics 3 Chlorhexidine 4 Alcohols 5 Hydrogen peroxide 6 Detergents amp soaps 7 Heavy metals 8 Aldehydes 9 Gases 10 Dyes 1 Halogens intermediate discupts disulfide bonds of proteins Chorine CIZ chlorine bleach chloramines used for water sewage inanimate objects UNSTABLE in sunlight inactivated by organic matter form byproducts trihalomethanes carcinogenic to reduce 1THM in water plants switch from chlorination chloramine process make chloromine with ammonium TI39HM can be reduced ways to reduce 1THM in home filter boil distill bottled water activated carbon Iodine iodophors used for medicaldental things antiseptic prep before surgery handscrub mediumeve for disinfectant of medical tools III I 2 Phenolics llo v 39 quot disrupt cell proteins lysol triclosan antibacterial additive to soaps 3 Chlorhexidine Iowintermediatel surfactant protein denaturant milder than phenols hibicens hibitane skin degerming agents for preoperative scrubs skin cleaning amp burns 4 Alcohols intermediate surfactant dissolving membrane lipids amp denaturing proteins of vegetative bacterial cells amp fungi ethy isopropyl solutions 5095 5 ijgrgeg Peroxide lowhigh produce highly reactive hydroxylfree radicals damage protein amp DNA while decomposing to 02 gas that s toxic to anaerobes low antiseptic high sporicidal 6 Detergent amp Soaps low Quaternary ammonia compounds surfactants that alter membrane permeability of some bacteriafungi Soaps mechanically remove soil amp grease containing microbes 7 Heavy Metals low Silver amp Mercury ki vegetative cells in low concentrations by inactivating proteins Mercury Merthiolate amp Metaphen weak antiseptics Silver Silver Nitrate mouth ulcers amp root canals Silver Sulfadiazine Ointment added to dressings to prevent infection 8 Aldehydes intermediatehigh Glutaraldehyde 2 solution cidex used as sterilant for heat sensitive instruments high level Formaldehyde 37 solution aqeous solution disinfectant preservative toxicity limits use intermediatehigh level 9 Gases hi h Ethylene oxide propylene oxide alkylating agents sterilize amp disinfect heat sensitive plastics amp prepackaged devices foods 10 Dyes low level narrow activity Aniline dyes act on grampositive bacteria amp fungi antiseptics amp wound treatment 11 Acids amp Alkalis low Organic acids prevent spore bacterial fungal growth canned tomatoes Acetic acid prevent bacterial growth Propionic acid retards molds Lactic acid prevents anaerobic bacterial growth Benzoic amp Sorbic acid inhibit yeast Cha pter Antibiotics Antibacterias Antibiotics metabolic products of aerobic bacteria amp fungi that inhibit other microbes in same habitat causing less competition for nutrients amp space bacteria genera steptomyces amp bacillus mods genera penicillum amp cephalosporium Mechanisms of Drug Action 1 Inhibit cell wall synthesis 2 Breakdown of cell membrane 3 Inhibit Nucleic Acid Synthesis 4 Inhibit protein synthesis 5 Block metabolic pathway 6 New Drugs formulated from preexisting drugs 1 Drugs that Inhibit Cell Wall Synthesis BetaIactam antimicrobials 3 carbon 1 nitrogen ring primary mode of action to interfere with cell wall synthesis 12 all antimicrobic drugs penicilin amp cephalosporins block cross linking of peptidoglycan9cell Iysis work on young growing cells only broad spectrum penicillin amp cephalosporins can cross outer membrane of Gr bacteria Peneciin Penicillin G amp V natural forms Gr streptococci some Gr meningococci amp syphilis Semisynthetic penicillins ampicillin carbenicillin amoxicillin broader spectra Gr Peniciinase resistant methicillin nafcillin cloxacillin Primary problem allergies amp resistant strains of bacteria Cephaosporins Synthetically altered betaIactam structure 13 of all antibiotics broadspectium resistance to most penicillinases fewer allergic reactions 4 generations exist each more effective against gram than previous cephaothin gram cocci some gram cefacor gram cephalexin broad spectrum against enteric bacteria with betalactamases cefepime widest range gram amp gram NON BetaIactam antimicrobials Vancomycin narrowspectrum toxic amp restricted treats staphylococcal infections if penicillinmethicillin resistance or allergy Bacitracin narrowspectrum produced by bacillus subtilis used topically in ointment soniazid treats mycobacterium tuberculosis interefers with mycolic acid 2 Drugs that Disrupt Cell Membrane Function damages membranedisrupts metabolism amp integrity9 cell lysis polymyxins disrupt phospholipids causing leakage gram marrowspectrum fatty acid component treat drug resistant Pseudomonas aeruginosa amp UTI 3 Drugs that Inhibit Nucleic Acid Synthesis quinolones inhibit DNA helicases don39t overuse to prevent ciprofloxacin resistant bacteria chloroquine crosslinks double helix fluroquinolenes inhibit gyrase analogs of purines amp pyrimidines insert in viral nucleic acid inhibit replication 4 Drugs that Inhibit Protein Synthesis broad spectrum work against bacterial ribosomes but can also damage eukaryotic mitochondria aminoglycosides insert on 305 subunit amp cause misreading of mRNA 6C ring amp 2 sugars structure use against aerobic gram amp some gram streptomycin bubonic plague tularemia TB amikacin gram bact gentamycin less toxic gram rods tetracyclines block attatchment of tRNA on A acceptor site amp stop further synthesis STDS rocky mountain spotted fever lyme disease typhus acne amp protozoa chloramphenicol block peptide bond formation inhibiting protein syn nitrobenzene structure chemicaly synthesized toxic amp lmtd use damage b marrow thyphoid fever brain abscesses rickettsial amp Chlamydia macrolides attach to 505 subunit low toxicity arge lactone ring with sugars taken orally for mycoplasma pneumonia legionellosis Chlamydia pertussis diphtheria amp as prophylactic before intestinal surgery for penicillin resistant gonococci syphilis acne new semisyn clarithomycin azithromycin 5 Drugs that Affect Metabolic Pathways sulfonamides amp trimethoprim inhibit enzyme required for tetrahydrofolate synthesis needed for DNA amp RNA synthesis most synthetic competitive inhibition drug must compete with normal substrate for enzyme s active site synergistic effect combination of antibiotoics gt individual antibiotics sulfonamides narrow block syn of folic acid sulfisoxazole shigellosis UTI protozoan infections silver sulfadiazine burns eye infections trimethoprim given wsulfamethoxazole UTI PCP 6 New Drugs Fosfomycin Trimethamine phosphoric acid that inhibits cell wall synthesis UTls Synercid use against I 39 39 amp cause 39 quot 39 ampsurgica39 39 when bacteria resistant inhibits protein synthesis Daptomycin used against gram disrupts membrane function Ketolides used when resistant to macrolides Oxazolidinones blocks protein synthesis methicillin resistant staph Aureus vancomycin resistant enterococcus Antifungals 1 Macrolide Polyene distrupt sterols9leakage9lysis Amphotericin B mimic lipids most versatale sys amp top Nystatin topical 2 Griseofulvin sturbbon derm Infections nephrotoxic 3 Synthetic azoles broad spectrum ketoconazole clotrimazole mionazole 4 Flucytosine analog of cytosine treat cutaneous mycoses or wamphotericin B treat systemic mycoses 5 Echinocandins capsofungin damage cell walls Chemotherapy Drugs Antiparasitic Chemotherapy Antimaaria drugs quinolones such as chloroquinine crosslinks double helix inhibiting replication Antiprotozoan drugs metronidazole flagyl quinicrine sulfonamides block synthesis of folic acid amp tetracyclines block attachment of tRNA A site Antiheminthic drugs expel parasitic worms immobilize disintegrate amp inhibit metabolism Membendazole Thiabendazole broadspectrum inhibit microtubules amp glucose utilization Pyrantel Piperazine paralyze muscles Nicosamide destroys scolex tapeworm Antiviral Chemotherapy Selective toxicity impossible because parasitic nature of viruses Block penetration9host cell Block replicationtranscriptiontranslation of viral genetic material Nucleotide analogs acyclovir herpes viruses ribavirin guanine analog RSV hemorrhagic fevers AZT thymine analog HIVAIDS blocks viral DNA synthesis from viral RNA using nucleoside reverse transcriptuse inhibitors Prevent maturation protease inhibitors HIV Antiherpes Drugs Mimic structure of nucleotides to compete for sites on replicating DNA Ora amp topical herpes chickenpox shingles Acyclovir zovirax Valacyclovir valtrex Famiciclovir famvir Peniciclovir denavir Drugs for Treating lnfluenza Amantadinerimantidine ONLY influenza A prevent fusion of virus with cell membrane Relenza amptamiflu broader influenza A amp B blocks neuraminidase lnterferons humanproduced glycoprotein produced by fibroblasts amp leukocytes bene ts reduces healing time amp complications of infections cold amp papillomavirus slows cancers leukemia amp lymphomas treats hep C genital warts amp Kaposi s sarcoma
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