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Y2 MCD Microbiology > bacterial infections > Flashcards

bacterial infections Flashcards

community acquired infections: define an outbreak of infectious disease and explain how outbreaks are identified; list bacterial pathogens that cause community acquired infection, explain the routes and types of infection caused, and list important bacterial virulence factors

1
Q

components of bacterial cell

A

ribosomes, DNA, cell wall, cytoplasm, cell membrane; capsule, flagellum, pili

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2
Q

common virulence factors

A

diverse secretion systems, flagella (move, attach), pili (adhere), capsule (protect vs phagocytosis), endospores (dormant bacteria which are temperature, dessication and chemical resistant), biofilms (organised aggregates which cause antibiotic resistant), endotoxins, exotoxins

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3
Q

bacteria with capsule

A

Step. pneumoniae

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4
Q

2 bacteria with endospores

A

Bacillus sp., Clostridium sp.

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5
Q

2 bacteria with biofilms

A

Pseudomonas aeruginosa, Staph. epidermidis

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6
Q

5 types of exotoxins and what they act on/stimulate/allow

A

neurotoxins (act on nerves or motor endplate), enterotoxins (act on GI tract), pyrogenic exotoxins (stimulate release of cytokines), tissue invasive exotoxin (allow bacteria to destroy and tunnel through tissue), miscellaneous exotoxin (specific/not well understood)

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7
Q

examples of bacteria producing neurotoxins

A

Tetanus, Botulinum

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8
Q

examples of bacteria producing enterotoxins (infectious diarrhoea)

A

V. cholera, E. coli

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9
Q

examples of bacteria producing enterotoxins (food poisoning)

A

B. cereus, Staphy. aureus

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10
Q

examples of bacteria producing pyrogenic toxins

A

Staph. aureus, Strep. pyogenes

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11
Q

what do bacteria which cause tissue invasive exotoxin contain

A

enzymes that destroy DNA, collagen, fibrin, RBC, WBC etc.

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12
Q

examples of bacteria causing tissue invasive exotoxin

A

Staph. aureus, Strep. pyogenes

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13
Q

example of bacteria causing miscellaneous exotoxin

A

B. anthracis

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14
Q

what is an endotoxin

A

lipid A component of LPS (not protein) in gram -ve bacteria

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15
Q

gram +ve vs gram -ve

A

gram +ve has thick peptidoglycan layer, gram -ve has thin peptidoglycan layer and another layer of LPS

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16
Q

why can treating patient with gram -ve infection with antibiotics sometimes worsen condition

A

bacteria lyse, releasing large quantities of LPS and endotoxin, causing septic shock

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17
Q

5 things which are determined following an outbreak

A

causative agent, illness, source, time frame, scale

18
Q

what can be used to detect outbreak strain

A

PCR (isolates can be screened by multiplex PCR for characteristic features of outbreak strain; can be done on stool samples); can then compare outbreak strain with known strains (determine what toxins have transferred to strain via bacteriophage)

19
Q

describe Shiga toxin structure

A

have an AB5 subunit composition, with toxin (StxA) which can block protein synthesis in eukaryotic cells

20
Q

what determines what a bacteria acts on in body

A

strains and virulence factor

21
Q

define outbreak

A

greater-than-normal or greater-than-expected number of individuals infected or diagnosed with a particular infection in a given period of time, or a particular place, or both

22
Q

how can an outbreak be identified

A

surveillance provides an opportunity to identify outbreaks; good and timely reporting systems are instrumental to identify outbreaks

23
Q

6 types of communicable diseases in Europe

A

respiratory tract infections, sexually transmitted infections, food and waterborne diseases and zoonoses, emerging and vector-borne diseases, vaccine-preventable diseases, antimicrobial resistance and healthcare-associated infections

24
Q

examples of respiratory tract infections

A

influenza (virus), TB (gram +ve), SARS (virus), avian influenza (virus), Legionnaire’s disease (gram -ve)

25
Q

infection route of Legionella pneumophilia (causes Legionnaire’s disease)

A

inhalation of contaminated aerosols

26
Q

where does Legionella pneumophilia grow in humans (causes Legionnaire’s disease)

A

alveolar macrophages

27
Q

describe Legionella pneumophilia (causes Legionnaire’s disease) type IV secretion system

A

secretion of effector proteins by type IV secretion system allow bacteria to replicate in Legionella containing vacuole (LCV)

28
Q

why is treatment of TB (mycobacterium tuberculosis) more difficult

A

very different cell wall with extra lipid layer

29
Q

describe latent TB

A

can enter dormant state, as evidence of infection but no clinical signs and symptoms of active disease

30
Q

examples of sexually transmitted infections

A

HIV/AIDS (virus), syphilis (Treponema pallidum; gram -ve), Hep B and C (viral), gonorrhoea (Neisseria gonorrohoeae; gram -ve), Chlamydia trachomatis (gram -ve)

31
Q

describe Chlamydia trachomatis (gram -ve)

A

obligate IC pathogen, either causing STI or eye infection (causing blindness)

32
Q

describe Neisseria gonorrohoeae (gram -ve)

A

diplococcus; interacts with non-ciliated epithelial cells to establish infection in urogenital tract; has pili and antigenic variation to escape detection and clearance by immune system

33
Q

examples of food and waterborne diseases and zoonoses

A

anthrax, botulism, campylobacteriosis, cholera, infection with vero/shiga toxin producing E. coli, salmonellosis

34
Q

describe campylobacteriosis

A

small children are high risk group; due to undercooked poultry; adhesion and invasion factors, flagella motility, type IV secretion system, toxin

35
Q

describe Salmonella sp.

A

undercooked poultry, highest infection rate in small children; type III secretion system encoded on pathogenicity islands

36
Q

describe V. cholerae

A

acute, severe diarrheal disease needing prompt rehydration; type IV fimbria, cholera toxin carried on a phages

37
Q

describe how cholera toxin causes diarrhoea

A

AB5 toxin, with A subunit being enzymatic and makes cell produce signalling molecule which activates CFPR channel, pumping out Cl- and causing diarrhoea

38
Q

describe Listeria monocytogenes

A

risk group immunocompromised, elderly, pregnant and foetus; can enter non-phagocytic cells and cross tight barriers e.g. intestinal, foetal

39
Q

examples of emerging and vector-borne diseases

A

malaria, plague (Yersinia pestis - gram -ve), Q fever (Coxiella burnetti, gram -ve), SARS, smallpox, VHF, West Nile fever, yellow fever

40
Q

examples of bacterial vaccine preventable diseases

A

diptheria (gram +ve), invasive haemophilus influenzae disease (gram -ve), invasive meningococcal disease (gram -ve), invasive pneumococcal disease (gram +ve), pertussis (gram -ve), tetanus (gram +ve)

Y2 MCD Microbiology (9 decks)

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