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FunMed Week 8 > Introduction to Microbial World (Bacteria) > Flashcards

Introduction to Microbial World (Bacteria) Flashcards

1
Q

what are the relationships between humans and microbiota?

A

symbiosis = the long-term interaction between 2 different biological species

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2
Q

what is an infection?

what is the difference between a primary pathogen and an opportunistic pathogen?

A

infection: multiplication of a bacterial pathogen within the host

  • *primary pathogen:** causes disease when infection - not normally associated with host
  • *opportunistic pathogen:** only causes disease in compromised host: sometimes part of normal flora

virulence: quantative ability of a microbe to cause disease

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3
Q

what are 4 basic microbes that can cause pathogens?
what kingdom are they each/

A
  • *1. bacteria:** prokaryote
  • *2. viruses:** non living
  • *3. fungi:** eukaryote
  • *4. protoza:** eukaryote
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4
Q

how do bacteria store DNA?

other general strucutture like?

  • orgenelles like what?
  • around outside?

how divide?

A
  • *DNA/RNA:**
  • *- single circular chromosome** that lies free in cytoplasm
  • *-** sometimes: additional plasmids

structure:

  • *-** free floating / non membrane organelles
  • cell wall
  • can have: flagella (motility)
  • pili / fimbriae: adherence
  • 70S rb (50S & 30S)

Division:
binary fission

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5
Q

what is S of bacteria ribosomes?

A

70S ribosomes (two subunits with densities of 50S and 30S)

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6
Q

what are some bacteria covered in?
what are pili used for?

what are bacteria spores?

A

some bacteria: capsulate (polysaccaride). evades immune response
pili: adherence to surfaces

bacterial spores: structures very resistant to physical & chemical agents. often go into dormant state. e.g. Bacillus anthracis, C. difficile

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7
Q

name functions of bacterial cell wall

what are the two different types of bacterial cell wall?

A

function:

  • protects agaisnt desiccation, osmotic shock & mech. shock
  • protection agaisnt host immune system: specifc and non-specific
  • adherence to surfaces

types:

  • *- gram postive
  • gram negative**
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8
Q

what determines if bacterial cell wall is gram postive or gram negative?
what else is different between them?

what colours do they stain?

A

depends on level of peptidoglycan: (and therfore the staining)

  • *- thick peptidoglycan:** gram postive - purple stain
    a) just one membrane
    b) lipotechoic acids sticking out
  • *- thinner peptidoglycan:** gram negative - negative stain
    a) have inner and outer membranes
    b) lipopolysaccarides sticking out
    c) holes in outermembrane
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9
Q

which one of these is gram +ve / -ve?

A

+ve = left / -ve right

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10
Q

what are 3 main shapes of bacteria?

A

Spherical (cocci)

Cylindrical rod (bacilli)

Curved/spiral (spirochetes)

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11
Q

differences between bacteria and eu cells?

A
  • nucleus: eukaryotes - membrane-bounded, bacteria: floating (also plasmids)
  • RB: eukaryotes: 80S (60S & 40S), bacteria: 70S (50S & 30S)
  • organelles: eukaryotes - mitochondria, golgi apparatus, lysosomes, peroxisomes and ER, bacteria: not those

bacteria divide by binary fission

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12
Q

what does gram stain rely on to show differences in bacteria?

what stain do u use for: a) Mycobacteria, b) fungi & c) spirochaetes? (probs dont need to know tbh)

A

differences in cell wall (amount of peptidoglycan):

  • *- gram postive** = purple
  • *- gram negative =** pink

  • ( a) Mycobacteria: Zielh-Nielson stain
    b) fungi: Cotton blue stain
    c) spirochaetes: darkfield microscopy )*
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13
Q

process of gram staining?

A

Gram stain: Crystal violet –> Iodine –> Ethanol –> Safranin

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14
Q

how are gram postive cocci subclassed? how do u test?

A

gram postive cocci - to differentiate between cocci do catalase test

  • streptococci: catalase negative
  • straphylocci: straphylocci positiive

subclassify straphylocci further: coagulase stain:

  • **straphylocci coagulase +ve
  • straphylocci coagulase -ve**

subclassify Streptococci further:: if can lyse blood or not

  • *- beta-haemolytic: lyse blood - complete haemolysis
  • alpha-haemolytic:: partially lyse blood
  • non-haemolytic: dont**
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15
Q

how do subdivde & test for different:

a) Staphylococci?
b) streptoccoi?

A
  • *staphylococci**: if can coagulate human serum or not
    • S. aureus (important human pathogen):* coagulates human serum: coagulase positive
    • S. epidermidis (non disease):* does not coagulate human serum: coagulase negative
  • *Streptococci:** if can lyse blood or not
  • beta-haemolytic: lyse blood - complete haemolysis
  • alpha-haemolytic:: partially lyse blood
  • non-haemolytic: dont
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16
Q

what are staphylococcal disesases - localised and systemic/>

A
  • *localised:
  • pyogenic (**pus making)
  • abscesses
  • wound infections
  • follicultis
  • *- MSK:**
  • osteomyelitis
  • *- Resp infection:**
  • sinustis
  • pneumonia
  • *generalised, systemic** (into blood)
  • bacteraemia, sepsis, endocarditis (infection of heart)
17
Q

name 3 staphylococcoal diseases that caused by entrotoxins?

A
  1. acute staph. enterocolitis (food pois)
  • *2. staphylococcal ‘scalded skin’ syndrome:**
  • Ritters disease
  • caused by exofoliative exotoxin
  • *3. toxic shock sydrome**
  • severe immune response to certain strains of staph. cause superantigens: high fever, rash, low BP, coma, multple organ failure
18
Q

difference in structure of steptococci and staphylococci bacteria?

A

streptococcus: chains
staphylococcus: clusters

19
Q

how are beta-haemolytic steptococci divided?

A

groups: A-G

depends on which Lancefield antigen is detected on surface

20
Q

disease caused by Streptococcus pyogenes (Group A)?

A
  • Streptococcus pyogenes* (Group A)
  • sore throat
  • fever
  • rash (strawberry tongue) - scarlet fever
  • tonislitis
  • infection of upper dermis. if on face: erysipelas ; arm: cellulitis. deeper that skin: can develop into sepsis, flesh eating strep
21
Q

gram negative rod bacteria?

2 main groups?

A

gram negative rods:

  • Obligate pathogens:**
    1. S    almonella sp: S. typhi, S. paratyphi*
    2. Shigella sp: S. dysenteriae, S flexneri, S. sonnei, S. boydii
    3. Klebsiella pneumoniae
    4. Yersinia sp: Y. entrocolticia, pseudotuberculosis
  • *Opportunistic pathogens** (mostly live in our gut):
    1. Escherichia coli
    2. Enterobacter sp: E. aerogenes, cloacae
    3. Acinetobacter baumanii
22
Q

what are enterobacteriaciae?

A

Enterobacteriaceae are a large family of Gram-negative bacteria that includes a number of pathogens such as Klebsiella, Enterobacter, Citrobacter, Salmonella, Escherichia coli, Shigella, Proteus, Serratia and other species.

These pathogens are present in the human intestinal tract and are a normal part of the gut flora.

23
Q

what happens when enterobacteriaciae leave gut?

A

not good !

quite serious:

  • wound infection
  • UTI
  • septicaemia
  • neurosurgial meningitis
  • pneumonia
24
Q

how can u classify enterobacteriaciae?

A
  • *- fermentors
  • non-fermentors**
  • *fermentors**:
  • bacteria differ in their ability to produce acids from different sugars (monosac, disac, polysac and alchohol fermentation). used to differentiate bacteria.
25
Q

what are multitest ID systems?

A
  • combine dozens or organic / inorganic substrates: determine breakdown by colour changes
  • e.g. API (analytic profile index) 20: gives a biochemical code for the metabolic profile of that organism
26
Q

which bacteria arent detected by gram stain - why?

which stain used instead - what shows up?

A
  • *mycobacteria**
  • waxy cell wall - lipid rich: resistance to drying, antiobiotics and disinfectants, acids and alkalis, survives in macrophages
  • e.g. M**ycobacterium tuberculosis

stain:
Ziehl-Neelson stain -stained bright red
(dont take up gram stain: called Acid-fast)

27
Q

why cant use gram stain for spirochaetes?

name 2 diseases caused by ^?

A

too thin cell wall to see with gram stain

  • Boreelia burgdoferi: Lyme disease
  • Treponema pallidium: syphilis
28
Q

what important fungi that can see with gram stain?

A

Candida sp: much bigger cocci than bacteria. cause thrush

29
Q

what is Aspergilliosis?

A

Aspergillosis is an infection caused by a type of mold (fungus). The illnesses resulting from aspergillosis infection usually affect the respiratory system, but their signs and severity vary greatly.

30
Q

describe basic overview of protozoa

which kingdom?

how do u classify?

A

unicellular eu. organism: typical eu features but also species specific organelles
found in all aq. enviroment (incl. soil and humans)

kingdom: Protista

classify:
locomotion:
-pseudopodia
- flagella
- cilia

31
Q

name some protozoal diseases pls (3 types)

A

Apicomplexa: Plasmodium sp (malaria), Toxoplasma gondii, Cryptosporidium

Ameobae: Entamoeba histolytica

Flagelletes: Giardia (diarrhea, malabsorbtion), Leishmania

32
Q

what are Helminths?
how classified?

A
  • helminths: worms (intestinal parasites)
  • classifcation:
  • trematodes: flat, non segemented (e.g. Schisosomiasis) - flukes
  • cestodes: flat, segemented - tapeworms
  • nematodes: round and non segmented
33
Q

how do you diagnose infections?

A

need:

  • history of patient (travel, symptoms & duration, animals, food)
  • clinical exam
  • lab investigations: haemotological, biochemical, microbiology / virology
34
Q

what tests do u use if cant grow microbe (to test) ?

A

use serological / immunological diagnosis: look for antibodies being present / absent. important for viral infections and hard to grow bacteria

35
Q

future of bacterial ID? what are the techniques

A
  • MALDI-Tof MS (mass spec)
  • *- molecular tests**: PCR (look for bacterial genes) - standard PCR, Real-time PCR, Cephoid GeneXpert
  • *- whole genome sequencing
  • sequencing bacteria on usb things**

FunMed Week 8 (8 decks)

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