Microbiology Flashcards by Patricia Alexis Molino

Who first observed CELLS? And said that “all living things are composed of cells”

Robert Hooke (1665)

OO - hooke
LL - cells

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Who first observed MICROORGANISMS? (animalcules)

Anton van Leeuwenhoek (1673)

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Fermentation - Pasteur

1857

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When did Pasteur disprove spontaneous generation theory wherein life can arise from NON-living matter?

1861

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When was Koch’s postulate done?

1876

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Where is the DNA contained in a prokaryote?

Free in the cytoplasm bcs no nucleus

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Ribosome svedberg of prokaryotes and eukaryotes

Prokaryotes: 70s
Eukaryotes: 80s

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What are cylindrical bacteria which are convoluted in varying degrees?

Spirals

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Give 2 examples of diplococci

Neisseria gonorrheae

Streptococcus pneumoniae

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Cocci in chains

Streptococcus pyogenes

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Simple bacilli

Pseudomonas aeruginosa

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Actual spiral or helices

Spirillum minor

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What is an example of gram staining mtd?

Hucker’s staining

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Gram staining:

What are the

Primary stain
Mordant
Decolorizer
Counterstain

Primary stain: CV
Mordant: Iodine
Decolorizer: Acetone alcohol
Counterstain: Safranin

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Acid fast staining

What are the

Primary stain
Mordant (fixes 1° stain)
Decolorizer
Counterstain

Primary stain: Carbolfuchsin (30s)
Mordant: Heat
Decolorizer: Acid alcohol
Counterstain: Methylene blue

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Mechanisms of GS is related to:

1 Thickness of CW
2 Pore size
3 Permeability properties of the intact cell envelope

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Gram’s Rule

All cocci are G+ except NVM

All bacilli are G- except MCS (sporeformers e.g bacillus)

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Phenotypic basis classification

1 Environmental req (temp, O2/gas presence, pH lvls, ion/salt presence)
2 Nutritional req (utilize Ca, Nitrogen)
3 Resistance profiles (antibiotics, heavy metals, toxins)
4 Antigenic properties (immuno-sero: relatedness)
5 Subcellular properties (molec constituents that are typical of a particular taxon)

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What is a flagella at both poles called?

Amphitrichous

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Tuft of flagella at one pole like bundle in one side only, and sample of this is Salmonella typhi

Lophotrichous

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What is the difference of capsule and slime layer (glycocalyx)?

Capsule: regular and gelatinous

Slime layer: less regular and more diffuse

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What does the G+ have that the G- doesn’t?

Teichoic and Lipoteichoic acid - provides fxn rel to elasticity, porosity, tensile strength, and electrostatic properties of the envelope

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What does the G- have that the G+ lacks?

Outer membrane

Lipoprotein: stab other mem and anchors it to the peptido
Phospholipid: prevent leak of periplasmic CHON and protects the cell from bile salts & hydrolytic enz
LPS: endotoxin (fever, shock)
Porin protein - molecule passage

Periplasmic space - degrades, detox

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It serves as storage areas for nutrients and stain

Inclusions

1) Volutin - inorg phos –> ATP
2) Polysaccharide granules - glycogen & starch
3) Lipid incl
4) Sulfur granules

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What microbe grows best at low temps? (-5 to 15°C)

Psychrophile

What microbes grow best at 30-37°C?

Meso

What microbes grow best at 50-60°C?

Thermophiles

Physical requirements for microbial growth

Temp pH Osmotic pressure

Examples of obligate aerobes (need O2 to live)

Pseudomonas aeruginosa

Example of facultative anaerobe (fermentation or anaerobic respiration)

Salmonella

Obligate anaerobes

Bacteroides

Aerotolerant anaerobes

Streptococcus

Microaerophilic capnophilic

Streptococcus

Altered AA seq --> nonfxnal

Missense

Not code --> early truncated

Nonsense mutation

Insertion snd deletions, not divisible by 3

Frameshift mutation

Enz destruction of drug, altered targets for the antibiotic, and decreased cellular uptake of drug

Resistance to beta lactams

Altered CW precursors that don't bind to vancomycin

Resistance to glycopeptides

Modifying enzymes

Resistance to aminoglycosides

Decreased uptake or by production of an altered target

Resistance to quinolones

Equivalent to a bacterial suspension of 1.5x10^8 CFU/mL

McFarland turbidity stds (1% sulfuric acid and 1.175% BaCl)

What is the lowest antimicrobial conc that completely inhibits visible growth?

MIC (minimal inhibitory conc)

Depth of agar medium

4mm

How much is the maximum bdisks in a 159mm MH agar plate?

12 antibiotic disks

What may be performed in life-threatening infxns?

Minimal Bactericidal Conc (MBC) Test

What us the lowest conc of a drug that results in 99.9% killing of bact?

Minimal Bactericidal Conc (MBC) Test

What measures rate of killing over time?

Time kill studies lel

What tests the effectiveness of antimicrobial combi against a single bacterial isolate?

Synergy testing

Activity of antimicrobial combi is substantially greater than the activity of the single most active drug alone

Synergy Doc: "2 is better than 1" uwu

No bettern or worse than tye single most active drug alone

Indifference

The activity of the combination is substantially less than the activity of the single most active drug alone (an interaction to be avoided)

Antagonism Doc: "1 is better than 2" aye strong independent women/men

What is the term that means destruction of all forms of life including spores?

Sterilization

What is the process of elimination of microorganisms EXCLUDING spores?

Disinfection

Incineration temperature

870-980°C

What is the fastest and simplest physical mtd of sterilization?

Moist heat (stem under pressure)

Used to sterilize biohazardous trash and heat-stable objects | Uses autoclave 1 atm (15 psi) of pressure

Moist heat (stem under pressure)

Sterilization temperatures for media, liquids, and instruments

121°C (250°F) for 15 minutes

Sterilization temperatures for infectious medical waste

132°C (270°F) for 30-60 minutes

Requires longer exposure times (1.5 to 3 hrs) and higher than moist heat (160-180°C)

Dry heat

What is used to sterilize glassware, oil, petroleum, or powders?

Dry heat

Mtd of choice for antibiotic solns, toxic chem, radioisotopes, vaxx, carbs, wc are heat sensitive

Filtration

Sterilize disposables s/a plastic syringes, catheters, or gloves

Ionizing radiation

What is used in gaseous form of sterilizing heat sensitive obj?

Ethylene oxide (ETO)

A sporicidal in 3-10 hrs and used for med equipment s/a bronchoscopes, bcs it doesn't corrode lenses, metal or rubber

Glutaraldehyde

Effective in presence of organic material | Used for the surface sterilization of surgical instruments

Peracetic acid

Kills vegetative bacteria

Boiling at 100°C for 15 mins

What physical mtd kills food pathogens w/o damaging the nutritional value of the flavor?

Pasteurizing at 63°C for 30 mins or 72°C for 15 seconds

What is a chemical mtd of inactivating DNA and RNA thru alkylation of sulfhydryl grps?

Aldehyde | - they also hav irritating fumes

What is germicidal in 10 mins and sporicidal in 3-10 hrs?

Glutaraldehyde

What is germicidal in 10 minutes and spermicidal in 3-10 hrs?

Formaldehyde

Surface disinfectants | E.g chlorine (bleach), iodine

Halogens

Example of this is eye drop with 1% silver nitrate (newborns to prevent infxn w Neisseria gonorrheae)

Heavy metals

Reduce surface tension of molecules in a liquid | Pseudomonas aeruginosa is resistant to this

Quats or quaternary ammonium compounds

Not sporicidal Acts by pptating CHONs Found in germicidal soaps

Phenolics | E.g ortho-phenylphenol, -benzyl-para-chloroohenol

H2O2

Oxidizing agents

Temperature is directly proportional to the degree of

Disinfection

Resistant < or =

Ampicillin 17 Ceftriaxone 24 Meropenem 22 Co-trimoxazole R 17 I 18-29 S 21

All bacilli are gram negative except

Bacillus, Clostridium, Mycobacterium, Corynebacterium, Listeria, Nocardia, Erysipelothrix, Lactobacillus, Kurthia, Rothia.

E.g. of amphitrichous bacteria

Campylobacter jejuni

- act as detergents - more effective against G (-)

Polymyxins (B and Colistin)

Inhibit teichoic acid synthesis

Nalidixic acid

Permit rapid diffusion

Ionophores

Binds to membrane in Ca dependent manner causing depolarization of bacterial mem potential

Daptomycin

most are for topical use to avoid toxicity

Daptomycin

bind to the 50s portion and inhibits formation of peptide bonds

Chloramphenicol

changes shape of 30s portion causing code on mRNA to be read incorrectly

Streptomycin

interfere with the attachment of tRNA to mRNA ribosome complex

Tetracyclines

broad spectrum antibiotic

chloramphe

usually used for mycobacteria (pulmonary tuberculosis)

streptomy

alternative to patients with allergies to penicillin and penicillin derivative drugs

erythromycin

more common semi-synthetic drugs; better and deeper penetration than erythromycin

Azithromycin and telithromycin

used for penicillin-resistant gram-positive bacteria

Linezolid

Inhibit microbial DNA synthesis by blocking DNA gyrase

FLUOROQUINOLONES

bind strongly to the DNA dependent RNA polymerase of bacteria, inhibits bacterial RNA synthesis

RIFAMPIN

for herpes virus, shingles, chicken pox and hepatitis B infections

ACYCLOVIR

Microbiology Flashcards

(96 cards)