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Bacteria 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
how do you do a gram stain to show the difference between gram positive and gram negative
- 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
what diseases does streptococcus pyogenes cause
 Cellulitis  Erysipelas  Scarlet fever impetigo
27
what disease does staphylococcus aureus cause
```  Carbuncle  Abscess  Penuomina  Sepsis  Endocarditis  MRSA infections impetigo ```
28
describe enterobactiercae
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
describe spirochetes | - can they be shown with a gram stain
o Spiral shaped, thin cell wall, similar to Gram negative | o Can’t be shown with Gram stain
30
describe mycobactier a | - can they bee shown with a gram stain
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
how do you divide streptococci and staphylococci
catalase test
32
what is the result of the catalase test
- 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
describe the lancefield test
- 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
what is erysiphelas
- 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
what is cellulitis
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
Staphyloococcus identification ...
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
what are staphylococcal diseases
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
what are the staphylococcal diseases caused by toxins
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
How do you differentiate between enterobacteriacease
- Lactose fermenter (pink) - E.coli, klebsiella - Lactose non fermene (colourless) pseudomanonas salmonella - Lactose acts as a carbon source and inhibits gram positive growth
40
what are the growth requirements for bacteria
- Most bacteria are grown at 370C in air - Some require added carbon dioxide (CO2) - Some organisms only grow under anaerobic conditions
41
what are parasites
• Any living form which is dependent on other living forms for survival, and causing some damage to the host
42
what are the two types of parasites
protozoa and helminths
43
describe protozoa
o Unicellular eukaryotic organisms o Sporozoa o Amoebae o Flagellates
44
describe helminths
``` o Multicellular eukaryotic organisms with no backbone or exoskeleton o Trematodes (flukes) o Cestodes (tapeworms) o Nematodes (round worms and filarial) ```
45
describe fungi
* 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
Describe arthropods
* Important as vectors * E.g scabies * Produce poisonous venoms * Insects – e.g. flea, mosquito, louse * Arachnids
47
how are protozoa classified
- There means of locomotion
48
what are the types of protozoa
- 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
what are the examples of fungi
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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