Antimicrobials and major Phyla/Classes

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Microbiology
Chapters 10-13
Tailored to UCBEx's online Medical Microbiology class
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1

Abx that inhibit proper synthesis of new cell wall

Beta-lactams (Penicillins, Cephalosporin, Monobactam)

Vancomycin and cycloserine- interfere w/crosslinking

Bacitracin- blocks NAG/NAM secretion from cytoplasm

Isoniazid and ethambutol

2

Abx that inhibit protein synthesis

Streptomycin- some aminoglycosides alter 30S shape= mRNA misread

Tetracycline- block tRNA docking site (A site)

Chloramphenicol- block peptide bond formation

Lincosamides & Macrolides- bind 50S, block mRNA movement

3

Abx that inhibit general metabolic pathways

Atovaquone- interfere with ETC of protozoa & fungi

Heavy metals- inactivate enzymes

Niclosamide- disrupt oxida. phos. of ATP in many protozoa & helminths

Amantadine- inhibit viral uncoating in Influenza A

Sulfanilamide- analog of PABA; irreversibly binds enzyme for folic acid synth, which is required for nucleic acid synth

4

Abx that inhibit nucleic acid synthesis

Nucleoside analogs- acyclovir, AZT, ribavirin - don’t properly base-pair

quinolones/fluoroquinolones- target prok. DNA gyrase

5

Abx that disrupt cytoplasmic membrane

Amphotericin B- attaches to ergosterol in fungi, forms membrane channels. Human cholesterol=somewhat susceptible. Bacteria=no effect

Azoles & allylamines- inhibit ergosterol synthesis= only target fungi

Polymyxin- target membrane in gram (-), esp. Pseudomonas .

  1. Toxic to human kidney
6

Antiviral to prevent viral attachment/entry

Arildone- block Poliovirus attachment

7

Low G+C Gram (+) bacteria

  1. Phylum Firmicutes:
    1. Clostridia: bacilli, obligate anaerobes, endospores, toxins
    2. Mycoplasma: facultative/obligate anaerobes, no cell walls (pleomorphic), smallest free-living cells
    3. Bacillus- soil; endospores
    4. Listeria- milk/meat contaminate;
    5. Lactobacillus- normal in body; yogurt
    6. Streptococcus
    7. Enterococcus
    8. Staphylococcus
8

High G+C Gram (+) bacteria

  1. Phylum Actinobacteria
    1. Corynebacterium: pleomorphic aerobe/ facultative anaerobe; produce metachromatic granules (PO4 storage)
    2. Mycobacterium: aerobic rods/filaments; slow growth due to mycolic acid on cell walls/ acid-fast stain
    3. Actinomycetes: branching filaments (like fungi)
    4. Actinomyces: in mouth
    5. Nocardia: degrades pollutants
    6. Streptomyces: make Abx (erythromycin, tetracycline)
9

Phylum Proteobacteria: Class Alpha

nitrogen fixers, nitrifying bacteria, can live in vinegar and low nutrient water baths

Pathogens: Rickettsia, Brucella

10

Phylum Proteobacteria: Class Beta

  1. Pathogens:
    1. Neisseria- gonorrhea, meningitis
    2. Bordetella- Pertussis(whooping cough)
    3. Burkholderia- moist environments
  2. Non-pathogens: recycle sulfur into sulfate, waste treatment
11

Phylum Proteobacteria: Class Gamma

Most diverse class

  1. Intracellular pathogens:
    1. Legionella- eat amino acids, in macrophages; Legionnaires Disease
    2. Coxiella- low pH, in macrophages, Q fever
  2. Methane oxidizers
  3. Glycolytic facultative anaerobes (Enterobacteriaceae): Escherichia, Salmonella, Shigella, Yersinia, Vibrio; cause gastroenteritis and plague
  4. Pseudomonas- UTIs
12

Phylum Proteobacteria: Class Epsilon

Campylobacter- blood poisoning

Helicobacter- H. pylori, stomach ulcer

13

Other Gram (-) bacteria

Chlamydias-

  1. Chlamydia- small cocci, intracellular, cause chlamydia STD and neonatal blindness

Spirochetes- helical, axial filaments

Bacteroides- obligate anaerobe rods, comprise 30% of feces bacteria

    1. Treponema- Syphilis
    2. Borrelia- Lyme Disease
    3. Bacteroids
14

Protozoa: General Characteristics

  1. Eukaryotic, unicellular, no cell wall
  2. all motile but apicomplexa
  3. require moist environments
  4. Usually asexual, but some sexual
15

Parabasala

Protozoa; no mito;

ex: Trichomonas

16

Diplomonadids

Protozoa; no mito, golgi bodies, or peroxisomes;

ex: Giardia

17

Euglenozoa

Protozoa

Euglena- phototropic, no cell wall, flagella

Kinetoplastids- have kinetoplast (MRO);

ex: Trypanosoma, Leishmania

18

Alveolates

Protozoa

Ciliates- chemohetero, 2 nuclei

ex: Paramecium

Apicomplexans- chemohetero pathogens;

ex: Plasmodium, Toxoplasma

19

Fungi, Division Zygomycota

saprobes & obligate parasites

ex: Microsporidia, Nosema

20

Fungi, Division Ascomycota

Molds and yeasts. Food, Abx, pathogens

Ex: Tuber (truffles), Penicillium, Saccharomyces, Histoplasma

21

Fungi, Division Basidiomycota

Mushrooms and yeasts.

Ex: edible mushrooms, Cryptococcus neoformans (fungal meningitis)

22

Important Virus Families

      1. Herpesviridae: dsDNA
      2. Papillomaviridae: dsDNA
      3. Picornaviridae: ssRNA(+)
        1. Rhinovirus, Hep A, Polio
      4. Coronaviridae: ssRNA(+)
        1. SARS, cold
      5. Retroviridae: ssRNA(+) segmented
        1. HIV
      6. Rhabdoviridae: ssRNA(-)
        1. Rabies
      7. Filoviridae: ssRNA(-)
        1. Ebola
        2. Marburg (hemorrhagic fever)