General bacteriology

Question 1

Size of E.coli?

Answer 1

1x3

Question 2

Different types of bacteria?

Answer 2

• cocci
• rods
• comma
• spiral
• filamentous

Question 3

What types are clostridia, tremponema, staphylococcus, campylobacter?

Answer 3

• clostridia - rods
• Staph - cocci
• tremponema - spiral
• camp - comma

Question 4

How do you ID bacteria?

Answer 4

• shape
• size
• motility
• biochemical
• PCR
• sequencing
• serotyping
• stains
  
  • grams
  • sliver
  • ZN

Question 5

Difference between gram +ve and -ve?

Answer 5

• +ve
  
  • thick cell wall
  • no cell envelope
  • contain teichoic acid
• -ve
  
  • thin cell wall
  • have envelope
  • no teichoic acid

Question 6

What are the exceptions to this rule?

Answer 6

• Microbacteria = gram +ve, dont stain well - ZN
• Spirochaetes = gram -ve, dont stain well - sliver

Question 7

Mycoplasma?

Answer 7

• very small
• no cell wall
• very few genes
• many antibiotics dont work against them
• cause arthritis, abortion, infertility, mastitis, meningitis, pneumia

Question 8

Ecoli and Mycobacterium tuberculosis doubling time?

Answer 8

• e.coli = 20 mins
• M. TB = 20 hours

Question 9

How do you culture bacteria?

Answer 9

• nutrients - agar or broth
• 28-42 degrees
• oxygen presence?
• additives or antibiotics to get rid of unwanted bacteria

Question 10

Answer 10

Question 11

What are the factors influencing infection?

Answer 11

• bacteria:
  
  • diversity
  • pathogenic determinants
  • genetic exchange
• host
  
  • susceptibility
  • dose response
  • latency
  • immunity
• environment
  
  • survival
  • amplification/ numbers
  • transmission routes
  • interventions

Question 12

What is an infectious disease?

Answer 12

• a disease caused by a microorganism and therefore is potentially transferable to new individuals (may or may not be communicable/ contagious)

Question 13

What is a contagious disease?

Answer 13

• a disease capable of spreading rapidly from one individual to another via close contact or close proximity - parvo, MRSA

Question 14

What is a communicable disease?

Answer 14

• an infectious disease that is contagious and which can be transmitted from 1 source to another (same as contagious - human med)

Question 15

What is a non-contagious infectious disease?

Answer 15

• an infectious disease that is not transmitted through direct contact or exposure to contaminated environment e.g. blue tongue, malaria, lyme disease

Question 16

What are the different routes of transmission?

Answer 16

• horizontal - same or different generation e.g. direct contact, sexual transmission
• vertical - different generation (from mother to offspring)
• indirect
  
  • contaminated food/ water
  • actively or passively by vectors
  • air borne
  • contaminated equipment
  • infected lorries
  • environment

Question 17

What is E.coli VTEC?

Answer 17

• 1100 cases in UK/ year
• Hamburger bug - ground beef source
• low infective dose (<100 bugs)
• commensal in ruminants
• diarrhoel disease in humans + kidney complications (HUS)
• O157, O145, O26, O121, O103