Week 9 - Microbiology of GI tract

Question 1

Wha is the gram status of psuedomonas aeruginosa?

Answer 1

-Gram negative bacilli

Question 2

Give two examples of obligate aerobes

Answer 2

• Mycobacterium tuberculosis

- Pseudomonas aeruginosa

Question 3

Give two obligate anaerobes

Answer 3

• Bacteriodes fragilis

- Clostridium spp.

Question 4

Name the anaerobic areas of the GI tract

Answer 4

• Parts of the mouth
• Small bowel
• Colon

Question 5

Why are colonic bacteria essential for life?

Answer 5

• Prevent colonisation by pathogenic bacteria
• Synthesise and excrete essential vitamins eg B12
• Stimulate production of natural antibodies

Question 6

What are consequences of a diminished microbiota

Answer 6

• Increased susceptibility to infection
• Vitamin deficiencies
• Poorly developed immune system

Question 7

Name two bacteria which can form endospores

Answer 7

• Clostridium tetani

- Bacillus anthracis

Question 8

Name 3 aerobic gram positive cocci species

Answer 8

• Staphylococcus
• Streptococcus
• Enerococcus

Question 9

Name 2 aerobic gram negative cocci

Answer 9

• Neisseria meningitidis

- Neisseria gonorrhoeae

Question 10

Name some gram positive bacilli species

Answer 10

• Clostridia

- Lactobacillus

Question 11

Name 3 gram negative enteric bacilli

Answer 11

• E.coli
• Bacteriodes fragilis
• Pseudomonas
• Klebsiella spp
• Salmonella spp.

Question 12

What is the gram status of Haemophilus influenzae

Answer 12

-Gram negative bacilli

Question 13

Name some bacteria which colonise the mouth

Answer 13

• Strep
• Staph
• lactobacilli

Question 14

When can mouth bacteria begin to be problematic?

Answer 14

-When the host is malnourished, dehydrated or immunocomprimised

Question 15

Who is at risk of oral thrush?

Answer 15

• Neonates
• Immunocomprimised
• Antibiotics
• Diabetics
• Steroid use

Question 16

What is angular chylosis?

Answer 16

-Inflammation of corners of mouth caused by thrush

Question 17

How is oral thrush treated?

Answer 17

-Nystatin suspension

Question 18

What bacteria often causes dental caries/gingivitis?

Answer 18

-Step mutans (viridans)

Question 19

What is ludwig’s angina?

Answer 19

• Cellulitis of the neck, usually caused by strep mutans

- Rapid progression can lead to asphyxiation via closure of the larynx

Question 20

What three sites are swabbed for MRSA upon entering hospital?

Answer 20

-Nose, throat and perineum

Question 21

What are the main bacteria which colonise the nose?

Answer 21

-Strep and staph

Question 22

Name 3 bacteria which normally colonise the throat

Answer 22

• Viridans strep
• Staphylococci
• Niesseria Meningitidis

Question 23

When can viridans streptococci become problematic?

Answer 23

• During dental procedures and anesthesia bacteria may enter blood stream
• Usually cleared but can stick to prosthesis and orthopaedic implants and cause infection

Question 24

Which group of organisms is mainly responsible for tonsillitis? Name the common organism

Answer 24

• Viruses

- Adenovirus

Question 25

What is the main bacterial cause of tonsillitis?

Answer 25

-Strep pyogenes

Question 26

What is a quincy?

Answer 26

-Abscess of the tonsil

Question 27

What GI pathology is commonly associated with H.pylori?

Answer 27

-Duodenal/gastric ulcers

Question 28

Name 3 common colonic bacteria

Answer 28

- Bacteroides fragilis - Eschericia Coli - Enterococcus Faecalis

Question 29

Why are prophylactic antibiotics used in gut surgery?

Answer 29

-Operations on the gut often have abnormal flora and there is a high risk of wound infection

Question 30

Name an antibiotic regime used in surgical prophylaxis

Answer 30

-Co-amoxiclav

Question 31

What is pseudomembranous colitis?

Answer 31

-Inflammation of the colon caused by c.difficile infection

Question 32

What is the cause of a perianal abscess?

Answer 32

-Blockage of anal gland by faecal matter caused stasis of bacteria leading to multiplication and abscess formation

Question 33

What colonic bacteria are found perianal skin?

Answer 33

- E.coli | - Enterococcus

Question 34

Where are lactobacilli the common commensal?

Answer 34

-Vagina

Question 35

What makes lactobacilli advantageous to the vagina?

Answer 35

-Converts glycogen to lactic acid to creat an acidic environment which prevents other bacteria and candida albicans from growing

Question 36

What is the most common cause of UTIs?

Answer 36

-E.coli from GI tract | then enterococcus faecalis and klebsiella

Question 37

What is specific about an infection with pseudomonas aeruginosa?

Answer 37

-Produces green pus in moist environments

Question 38

What bacteria is responsible for wet/gas gangrene? Explain the process

Answer 38

- C.perfringes | - Anaerobic digestion of glucose leads to ethanol and CO2 producing bubbles in the skin

Question 39

Give two characteristic features of tetanus

Answer 39

- Risus sardonicus (lock jaw) | - Opisthotonus

Question 40

What is the most common cause of nausea and diarrhoea?

Answer 40

-Norovirus

Question 41

What is the most common cause of gastroenteritis?

Answer 41

-Contaminated food or drink

Question 42

What are the most common organisms which cause gastroenteritis?

Answer 42

- Salmonella - Campylobacter - Listeria

Question 43

What bacteria produce toxins in food which can cause nausea and vomitting?

Answer 43

- Staphylococci | - Clostridium

Question 44

What is the result of infection with vibrio cholera?

Answer 44

-Effects the ileum to cause water and salt to be actively secreted into the lumen leading to diarrhoea -Characteristically looks like 'rice-water' -Rapid severe dehydration follows (cholera)

Question 45

Name 2 protozoans which can cause gastroenteritis

Answer 45

- Giardia | - Cryptosporidium

Question 46

Name 4 causes of travellers Diarrhoea

Answer 46

- E.coli - Samlonella - Campylobacter spp. - Rotavirus

Question 47

What is the gram status of Staphylococcus?

Answer 47

-Gram positive cocci