Classifications of Pathogenic Bacteria: Gram Negative

Question 1

What does it mean for a bacteria to be gram negative?

Answer 1

The cell wall of the bacteria has a thin layer of peptidoglycan

Question 2

What colour do gram negative bacteria appear under the microscope?

Answer 2

Pink/red

Question 3

Why are gram negative bacteria pink under the microscope?

Answer 3

They have a very thin layer of peptidoglycan therefore they’re unable to
retain the crystal violet stain

Question 3

What % of terrible 12 bacterias are gram negative?

Answer 3

75

Question 4

How are gram negative bacteria divided up?

Answer 4

Aerobic
Aerobic (strict)
Microaerophilic
Anaerobic (strict)

Question 5

What is the shape of aerobic strict bacteria?

Answer 5

Bacilli

Question 6

What are the examples of aerobic strict bacteria?

Answer 6

Legionella sp
Pseduomonas aeruginosa

Question 7

What are the shapes aerobic bacteria can take?

Answer 7

Cocci
Bacilli (small and large)

Question 8

What are examples of aerobic cocci bacteria?

Answer 8

Neisseria gonorrhoea (gonorrhoea)

Neisseria meningitidis (meningitis)

Question 9

What are examples of aerobic small bacilli bacteria?

Answer 9

Bordetella pertussis (whooping cough)

Haemophilus influenzae (exacerbation of COPD)

Question 10

What are examples of aerobic large baciili bacteria?

Answer 10

Gut commensals
Gut pathogens

Question 11

What are examples of gut commensals?

Answer 11

E. coli

Klesbsiella sp.

Proteus sp.

Question 12

What gut commensals cause urinary tract infections?

Answer 12

E. coli

Klesbsiella sp.

Question 13

What gut commensals cause wound infections?

Answer 13

Klesbsiella sp.

Proteus sp.

Question 14

What are examples of gut pathogens?

Answer 14

Salmonella sp

Shigella sp

E. coli 0157

Question 15

What shape do microaerophilic bacteria take?

Answer 15

Bacilli (small curved and spiral)

Question 16

What is an example of small curved microaerophilic bacteria?

Answer 16

Campylobacter sp

Question 17

What is an example of spiral microaerophilic bacteria?

Answer 17

Helicobacter sp. (gastritis)

Question 18

What are the two shapes anaerobic strict bacteria can take?

Answer 18

Cocci (not relevant)
Bacilli

Question 19

What is an example of bacilli anaerobic strict bacteria?

Answer 19

Bacteroides sp. (gut commensals)

Question 20

What are the two major gram negative cocci groups?

Answer 20

Neisseria spp
Moraxella catarrhalis

Question 21

What bacteria causes meningitis?

Answer 21

Neisseria meningitidis (meningococcus)

Question 22

What is meningitis?

Answer 22

Inflammation of the meninges and septicaemia

Life threatening

Question 23

What is type of culture is important in meningitis?

Answer 23

Sample of cerebrospinal fluid

Question 24

What molecular test is available for N. menigitidis?

Answer 24

PCR on EDTA blood

Question 25

What does neisseria gonorrhoeae cause?

Answer 25

Gonorrhoea Urethritis in men Pelvic inflammatory disease in women

Question 26

What example of gram negative coccus causes respiratory tract infections?

Answer 26

Moraxella catarrhalis - especially in those with underlying lung disease

Question 27

What are coliforms?

Answer 27

Organisms which are in the enterobacteriaceae family

Question 28

Where do gram negative bacilli usually colonise?

Answer 28

The gut

Question 29

What is lactose fermentation useful in?

Answer 29

Preliminary testing in classifying gram negative bacilli

Question 30

What is an example of a lactose fermenting coliform?

Answer 30

E. coli

Question 31

What can E. coli infect?

Answer 31

Humans and animals

Question 32

What are the several virulence mechanisms of E. coli?

Answer 32

Pili - Capsule - use to hide away from the host immune system Endotoxin - lots of damage to host Exotoxin - lots of damage to host

Question 33

What does E. coli ferment?

Answer 33

Lactose

Question 34

What is E. coli an important cause of?

Answer 34

Urinary tract infections (UTIs) Septicemia Meningitis Hospital acquired pneumonia

Question 35

How many serotypes are there of E. coli and what are they based on?

Answer 35

Over 160 based on O antigens (LPS)

Question 36

What toxins can E. coli produce?

Answer 36

Enterotoxogenic E.coli Enterohaemorrhagic E. coli

Question 37

What is the most common cause of traveler's diarrhoea?

Answer 37

Enterotoxogenic E. coli

Question 38

What does Enterohaemorrhagic E. coli give rise to?

Answer 38

Bloody dirrhoea Haemolytic uraemic syndrome (HUS) associated with E. coli 0157 - in childre, decontaminated water

Question 39

What are the features of salmonella spp. ?

Answer 39

Does not ferment lactose >1500 serotypes Whole genome sequencing Self limiting with or without bloody diarrhoea (!2-48hrs) Invasive - enters blood stream

Question 40

What is the second most common cause of bacterial diarrhoea in the UK?

Answer 40

Salmonella spp.

Question 41

What does shigella spp cause?

Answer 41

Diarrhoea - travl related in UK

Question 42

What does klebsiella spp cause?

Answer 42

UTI Hospital acquired pnuemonia

Question 43

What does proteus spp cause?

Answer 43

UTI

Question 44

What is an example of curved gram negative bacilli?

Answer 44

Campybacter spp

Question 45

What level of o2 does campybacter spp like?

Answer 45

Low levels microaerophilic

Question 46

What is the source of Campybacter spp?

Answer 46

Animals and chickens Spread via faecal-oral route

Question 47

What is Campybacter spp the cause of?

Answer 47

Most common cause of bacterial diarrhoea in the UK

Question 48

What is the incubation period for Campybacter spp?

Answer 48

2-5 days Self-limiting

Question 49

What type of bacteria has curved rods?

Answer 49

Helicobacter pylori

Question 50

What is the natural habitat of helicobacter pylori?

Answer 50

Human stomach

Question 51

What does helicobacter pylori do?

Answer 51

Damages mucosa, causes ulcers and strong risk factor for gastric adenocarcinoma

Question 52

What is a prime example of cocco-bacilli bacteria?

Answer 52

Haemophilus influenzae

Question 53

What can Haemophilus influenzae cause?

Answer 53

Respiratory tract infections second to S. pneumoniae

Question 54

What type of Haemophilus influenzae causes meningitis?

Answer 54

B type

Question 55

What does psuedomonas spp colonise?

Answer 55

Water and soil - drains, sinks, mops, medical equpiment

Question 56

What can psuedomonas spp cause?

Answer 56

Hospital acquired cause of sepsis eg UTI, bacteraemia, pneumonia (rare)

Question 57

What is psuedomonas spp feared in?

Answer 57

Cystic fiborsis

Question 58

What is psuedomonas spp resistant to?

Answer 58

Multiple drugs, making it hard to treat

Question 59

What type of infection do anaerobes play a role in?

Answer 59

Polymicrobial infection - very important un human GI tract and oral cavity

Question 60

What anaerobes are found in the gut?

Answer 60

Bacteriodes - can enter blood stream too

Question 61

What anaerobes are found in the mouth?

Answer 61

Prevotella and Porphyromonas

Question 62

What is bacteroides fragilis?

Answer 62

Fragile organism, part of normal colonic flora

Question 63

What can bacteroides fragilis cause?

Answer 63

Intra-abdominal abscess, may spread to other sites eg blood stream

Question 64

List the oral anaeobes

Answer 64

Prevotella Porphyromonas eg gingivalis Pasterurella spp Capnocytophoyga spp

Question 65

What are oral anaeobes important in?

Answer 65

Aeitology of periodontal disease Aspiration pneumonia Human and animal infection bites

Question 66

What are the most common gram negative bacteria?

Answer 66

E. coli Salmonella spp. Campylobacter spp. Psueodomonas spp. Helicobacter pylori Haemphilus influenzaae Bacteriodes and other anaerobes