Microbiology Flashcards
Who first observed CELLS? And said that “all living things are composed of cells”
Robert Hooke (1665)
OO - hooke
LL - cells
Who first observed MICROORGANISMS? (animalcules)
Anton van Leeuwenhoek (1673)
Fermentation - Pasteur
1857
When did Pasteur disprove spontaneous generation theory wherein life can arise from NON-living matter?
1861
When was Koch’s postulate done?
1876
Where is the DNA contained in a prokaryote?
Free in the cytoplasm bcs no nucleus
Ribosome svedberg of prokaryotes and eukaryotes
Prokaryotes: 70s
Eukaryotes: 80s
What are cylindrical bacteria which are convoluted in varying degrees?
Spirals
Give 2 examples of diplococci
Neisseria gonorrheae
Streptococcus pneumoniae
Cocci in chains
Streptococcus pyogenes
Simple bacilli
Pseudomonas aeruginosa
Actual spiral or helices
Spirillum minor
What is an example of gram staining mtd?
Hucker’s staining
Gram staining:
What are the
- Primary stain
- Mordant
- Decolorizer
- Counterstain
Primary stain: CV
Mordant: Iodine
Decolorizer: Acetone alcohol
Counterstain: Safranin
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
Mechanisms of GS is related to:
1 Thickness of CW
2 Pore size
3 Permeability properties of the intact cell envelope
Gram’s Rule
All cocci are G+ except NVM
All bacilli are G- except MCS (sporeformers e.g bacillus)
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)
What is a flagella at both poles called?
Amphitrichous
Tuft of flagella at one pole like bundle in one side only, and sample of this is Salmonella typhi
Lophotrichous
What is the difference of capsule and slime layer (glycocalyx)?
Capsule: regular and gelatinous
Slime layer: less regular and more diffuse
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
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
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
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