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FunMed Microbiology > Bacteria > Flashcards

Bacteria Flashcards

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Biology 101 flashcards
1
Q

What is microbiology

A
  • Microbiology is the study of life of organisms that are too small to be seen with naked eye and study of their effects on the living host
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2
Q

what is the good function of microbes

A
  • They are at the base of the food chain in oceans, lakes, rivers and soil
  • They participate in photosynthesis which generates food and oxygen – first organisms present on earth
  • Microbes break down waste (sewage treatment) and detoxify pollutants (oil, mercury) (bioremediation)
  • The microbiota – present at each body site affects numerous biological functions important for maintaining health (essential for development of immune system)
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3
Q

what a a microbial pathogen

A

a microbe able to induce a disease, an infection, in a given host

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4
Q

what is a primary pathogen

A

cause disease when infection, not normally associated with host

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5
Q

what is infection

A

multiplication of a bacterial pathogen within the host

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6
Q

what is pathogenicity

A

the ability of the microbe to cause disease (qualitative)

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7
Q

what is virulence

A

quantitative ability of a microbe to cause disease

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8
Q

what are normal microbiota

A

microogansism that can establish permanent colonies inside or on the body without inducing disease

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9
Q

what is the definition of symbiosis

A
  • long-term interaction between two or more different biological species
  • normal microbiota and the host exist in symbiosis
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10
Q

what are the types of symbiosis

A

Commensalism
Mutalism
Paratism

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11
Q

what is commensalism

A
  • one organism benefits and the other is unaffected

- example would be streptococcus in the mouth

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12
Q

what is mutualism

A
  • both organism benefit

- example would be E.coli synthesis vitamin K

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13
Q

what is parasitism

A
  • one organism benefits at the expense of the other

- for example, bacteria causing diseases like pathogens

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14
Q

what are the 4 basic microbial pathogens that cause infections in humans

A
  • bacteria
  • fungi
  • viruses
  • protozoans
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15
Q

describe prokaryotes

A 
•	Contain DNA and RNA but no nuclear membranes 
•	Unicellular
•	Bacteria 
•	Archea 
o	Live in extreme environments 
o	Cell wall Lack peptidoglycan 
o	Not associated with disease in humans
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16
Q

what are the types of prokaryotes

A
  • bacteria and archaea
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17
Q

what is the structure of bactiera

A
  • Single circular chromosome free in the cytoplasm
  • May contain additional small circular DNA fragments – plasmids (contain resistance genes)
  • No mitochondira or membrane bound organelles
  • May be have flagella – used for movment
  • May have pili for adherenece to structures
  • Some have a capsule to help evade the immune system - more resistant to phagocytosis
  • Some contains spores which are very resistant to physical and chemical agents
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18
Q

How do bacteria divide

A

binary fission

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19
Q

what are the ribosomes in the bacteria

A

• Have 70s ribosomes (eukarytoes have 80s)

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20
Q

bacteria…

A

almost have a cell wall

21
Q

what does the bacteria cell wall do

A

 The cell wall is outside the plasma membrane
 Point of interaction with environment
 Protection against desiccation, osmotic shock, mechanical shock
 Adherence to host surfaces specifically or non-specifically
 Protection against host immune system, specific and non-specific
 Cell wall contains peptidoglycan; cross linked complex of polysaccharides(sugars) and peptides(proteins)
 Cell wall is rigid and imposes shape on the bacterium

22
Q

what are the two types of cell wall in bacteria

A

 Gram positive = thick and dense peptigoglycan with no outer membrane (stains purple) – techoic acid and lipotechoic acid markers
 Gram negative = thinner peptigoglycan with outer membrane (stains pink) – LPS markers – periplasm in between

  • they both have peptidoglycan
23
Q

what are the three main shape of bacteria

A
  • Spherical (cocci) examples include staphylococcus aureus, streptococcus pneumaniae, streptococcus pyogeners
  • Cylindrical rod (bacilli) – bacillus anthracis,
  • Curved spiral (spirochaetes) – vibrio challeage, barrela bugdroferi
  • may form pairs, chains or clusters
24
Q

How do you identify bacteria

A

o Microscopy – shape and staining – Gram stain
o Growth characteristics – lactose fermentation, aerobic or anaerobic growth
o Catalase test – Staphylococci are catalase positive, Streptococci are catalase negative
o Antigen detection
o Molecular tests – DNA probes, PCR, sequencing

25
Q

how do you do a gram stain to show the difference between gram positive and gram negative

A
  • Smear of bacteria
  • Add crystal violet (purple dye)
  • Application of iodine (mordant)
  • Wash with alcohol – use acetone
  • Gram positive – stain doesn’t wash off – purple
  • Gram negative – stain is washed of by acetone – use safranin to stain again – pink
26
Q

what diseases does streptococcus pyogenes cause

A

 Cellulitis
 Erysipelas
 Scarlet fever
impetigo

27
Q

what disease does staphylococcus aureus cause

A 
	Carbuncle
	Abscess
	Penuomina 
	Sepsis
	Endocarditis 
	MRSA infections 
impetigo
28
Q

describe enterobactiercae

A

o Group of Gram-negative bacteira
o Obligate – always pathogenic
o Pacultative – not always pathogenic – commensal
o Can ferment lactose – pink stain compared to yellow for non-fermenter

29
Q

describe spirochetes

- can they be shown with a gram stain

A

o Spiral shaped, thin cell wall, similar to Gram negative

o Can’t be shown with Gram stain

30
Q

describe mycobactier a

- can they bee shown with a gram stain

A

o Don’t take up Gram stain
o Thick wall with lomg hydrocarbons and some peptigoglycan
o Includes TB
o Ziehl Neelson stain to identify

31
Q

how do you divide streptococci and staphylococci

A

catalase test

32
Q

what is the result of the catalase test

A
  • Staphylococci are catalase positive
  • Streptococci are catalase negative – means that you are getting rid of the bacteria
    Staphylococci is divided into – do a coagulase test –
  • Coagulase positive (s.aureus) (produced coagulation)and coagulase negative (did not produce coajugation)
    Streptococci is divided into
  • Beta-haemolytic, alpha haemolytic and non-haemolytic
33
Q

describe the lancefield test

A
  • Beta haemolytic streptococci are divided into groups A to G depending on which Lancefield antigen is detected on their surface
  • S. pyogenes: Lancefield Group A
  • S. agalactiae: Lancefield Group B
34
Q

what is erysiphelas

A
  • Acute infection of upper dermis; skin rash on legs, toes, face, arms and fingers.
  • Skin lesions are warm and Fever, chills, fatigue, headaches
  • Streptococcus pyogenes = Group A Streptococcus (GAS)
35
Q

what is cellulitis

A

a spreading infection of the soft tissues

  • Commonly caused by Streptococcus pyogenes
  • This arm is red, hot, swollen and painful
  • Complications: Sepsis, Flesh-eating strep (necrotizing fasciitis)
  • Other main cause of cellulitis is infection by Staphylococcus aureus
36
Q

Staphyloococcus identification …

A

Staph. aureus shows yellow coloured colony on the mannitol salt agar
- coagulase negative staphylococci produces red pink colonies with no change of the media

37
Q

what are staphylococcal diseases

A
  1. Localised
    - Pyogenic infections – abscesses, folliculitis, furuncle/carbuncle, wound infections (postoperative, from skin surface)
    - Musculoskeletal – osteomyelitis
    - Respiratory infections – sinusitis, otitis media, pneumonia (usually young infants or hospital acquired infection)
  2. Generalise systemic
    - Bacteraemia
    - Sepsis
    - Endocarditis
38
Q

what are the staphylococcal diseases caused by toxins

A
  1. Acute staphylococcal enterocolitis: enterotoxins (A – E)
  2. Staphylococcal “scalded skin” syndrome
    - Ritter’s disease, “bullous impetigo”
    - Caused by exfoliative exotoxin
    causing upper skin layers lesions High fever, septicemia possible
  3. Toxic Shock Syndrome: Superantigens
    - High fever, rash, low blood pressure, malaise-confusion, can progress to coma and multiple organ failure
39
Q

How do you differentiate between enterobacteriacease

A
  • Lactose fermenter (pink) - E.coli, klebsiella
  • Lactose non fermene (colourless) pseudomanonas salmonella
  • Lactose acts as a carbon source and inhibits gram positive growth
40
Q

what are the growth requirements for bacteria

A
  • Most bacteria are grown at 370C in air
  • Some require added carbon dioxide (CO2)
  • Some organisms only grow under anaerobic conditions
41
Q

what are parasites

A

• Any living form which is dependent on other living forms for survival, and causing some damage to the host

42
Q

what are the two types of parasites

A

protozoa and helminths

43
Q

describe protozoa

A

o Unicellular eukaryotic organisms
o Sporozoa
o Amoebae
o Flagellates

44
Q

describe helminths

A 
o	Multicellular eukaryotic organisms with no backbone or exoskeleton 
o	Trematodes (flukes)
o	Cestodes (tapeworms)
o	Nematodes (round worms and filarial)
45
Q

describe fungi

A
  • Unicellular – yeast
  • Multicellular – molds and mushrooms
  • Characteristic of plant life but unable to photosynthesise
  • Cell wall made of mainly chitin
  • Have 80s ribosomes, membrane bound organelles, chromosomes and histones
  • Reproduce by forming spores
46
Q

Describe arthropods

A
  • Important as vectors
  • E.g scabies
  • Produce poisonous venoms
  • Insects – e.g. flea, mosquito, louse
  • Arachnids
47
Q

how are protozoa classified

A
  • There means of locomotion
48
Q

what are the types of protozoa

A
  • Pseudopeida - Entamoeba histolytica:amoebic dysentery
  • Flagella - Trypanosoma - sleeping sickness, Chagas disease Giardia – diarrhea -malabsorption
  • Cilia - Balantidium coli: Balantidiasis (diarrhea)
  • Apicomplexa (sporozoa) non-moving – gliding motility, - Plasmodium species: Malaria
49
Q

what are the examples of fungi

A

Aspergillosis: infects immunocompromised people. Hyphae may impede lung function and growth into tissues can cause damage and severe pneumoniae. Disseminated forms can lead to death
- Yeast – grow as single cells which divide by budding
Part of our commensal flora
Candida cause vaginal or skin infections in people ill, immuno-suppressed, or on antibacterial therapy. Causes thrush

FunMed Microbiology (7 decks)

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