Gram Positive Bacteria

Question 1

What are bacteria?

Answer 1

Single celled prokaryotes

Question 2

How do most bacteria reproduce?

Answer 2

through binary fission

Question 3

What do gram positive bacteria have which makes up a large portion of their cell wall?

Answer 3

Peptidoglycan

Question 4

What do gram negative bacteria have which makes up a large portion of their cell wall?

Answer 4

Lipopolysaccharides (lipid A is what makes the bacteria very toxic and causes the harmful disease) and outer membrane proteins

Question 5

What method can be used to distinguish between types of bacteria which are causing the infection?

Answer 5

Gram stain

Question 6

What are gram positive cocci which are present in clusters called?

Answer 6

Staphylococci

Question 7

What are gram positive cocci which are present in chains called?

Answer 7

Streptococci (enteroccci)

Question 8

What test is used to check for staphylococci?

Answer 8

Coagulase test

Question 9

What does it mean when coagulase test is positive for staphylococci?

Answer 9

If positive, then staphylococcus aureus is present which can be MSSA or MRSA

Question 10

Where is staphylococci carried?

Answer 10

Carried in nose, axilla perineum (groin area), hairline

Question 11

What disease are associated with staphylococci?

Answer 11

Wide range of diseases from: boils, soft tissue infections, septicaemia, cellulitis, skin abscesses, pneumonia, toxic shock syndrome and food poisoning (dangerous and non-dangerous)

Question 12

Why is staphylococcus aureus penicillin resistant?

Answer 12

It contains Beta- lactamase

Question 13

Why is MRSA causing problems for infection control? (3)

Answer 13

• They are methicillin resistant (staphylococci aureus)
• can mutate quickly
• resistant to penicillin (common antibiotics)

Question 14

What strain is associated with coagulase +ve test for staphylococcus?

Answer 14

Staphylococcus aureus

Question 15

What 3 strains are associated with streptococci?

Answer 15

• alpha haemolysis (partial)
• beta haemolysis (complete)
• non- haemolytic

Question 16

What colour does blood agar turn in alpha (partial) haemolysis?

Answer 16

turns green

Question 17

What colour does blood agar turn in beta (complete) haemolysis?

Answer 17

turns clear

Question 18

What effect does the non-haemolytic strain have on blood agar? (group D streptococci)

Answer 18

No effect

Question 19

What two strains does alpha-haemolytic streptococci include?

Answer 19

• streptococcus pneumoniae

- viridans streptococcus

Question 20

What does viridans streptococci cause?

Answer 20

endocarditis (infection and inflammation of the lining of the heart, especially the heart valves)

Question 21

What do streptococcus pyogenes cause? (Group A, Beta haemolytic)

Answer 21

-throat infections (sore throat)
-skin infections (e.g. cellulitis or necrotising fasciitis)
-scarlet fever
- acute rheumatic fever
-acute glomerulonephritis
Treated with penicillin

Question 22

What does Streptococcus Agalactiae cause? (Group B, Beta haemolytic)

Answer 22

• neonatal sepsis including meningitis and bacteraemia (usually spread from mother to baby through amniotic fluid)
• most people develop natural immunity to it because of constant exposure

Question 23

What is another name for bacteria in Group A strep for Beta haemolytic bacteria?

Answer 23

Streptococcus pyogenes

Question 24

What is another name for bacteria in Group B strep for Beta haemolytic bacteria?

Answer 24

Streptococcus agalactiae

Question 25

Where is Group D enterococcus faecalis found? (non-haemolytic)

Answer 25

Found in the gut as a normal commensal

Question 26

What does Group D enterococcus faecalis cause? | non-haemolytic

Answer 26

- Gut commensal. - Can cause UTI. - VRE an increasing problem in some hospitals (vancomycin resistant enterococci)

Question 27

What does Clostridium Difficile cause?

Answer 27

- pseudomembranous colitis (inflammation of the colon) - DIARRHOEA (because of toxin production) - nausea - abdominal cramps - pyrexia (high temp) - anorexia (loss of appetite)

Question 28

What increases a person's chances of getting clostridium difficile?

Answer 28

Taking large amounts of antibiotics

Question 29

Where does clostridium perfringens cause ?

Answer 29

- present in soil and normal commensal (flora) in normal human and animal gut/ faeces - toxigenic strains cause food poisoning - Main cause of "gas gangrene" - Serious infection treated with penicillin and/or metrondiazole.

Question 30

What does clostridium perfringens contaminate/infect?

Answer 30

- food (enterotoxin producing strains lead to food poisoning) - serious wounds which causes gas gangrene

Question 31

What do toxins from clostridium tetani cause?

Answer 31

- Cause of tetanus due to toxin acting on CNS. | - Toxoid used for immunisation.

Question 32

Why is tetanus caused? (linked to NMJ)

Answer 32

Loss of inhibition at neuromuscular junction which causes uncontrollable muscle spasms

Question 33

What are the 4 main anaerobic bacilli? (clostridiums)

Answer 33

1. clostridium difficile 2. clostridium tetani 3. clostridium perfringens 4. clostridium botulinum

Question 34

What are the 2 aerobic small bacilli groups? And what do each cause?

Answer 34

1. corynebacterium (diphtheria) | 2. listeria monocytogenes (meningitis)

Question 35

What are the 2 aerobic large bacilli groups? And what do they cause?

Answer 35

- bacillus cereus (food poisoning) | - bacillus anthracis (anthrax)

Question 36

What does Staphylococcus aureus cause?

Answer 36

- Normal flora in nose and skin. - Major pathogen in skin, endocarditis, cellulitis, abscesses, osteomyelitis, toxin mediated food poisoning and toxic shock syndrome. Affect skin and soft tissue

Question 37

What are the main symptoms of streptococcus pyogenes? (strep throat)

Answer 37

- red and swollen tonsils - throat pain (pain swallowing) - swollen/tender lymph nodes in the neck - fever, rash, vomiting

Question 38

What are the main symptoms of streptococcus pneumoniae?

Answer 38

- fever (pyrexia) and headache - cough - shortness of breath - chest pain - stiff neck - disorientation and confusion - chills - ear pain

Question 39

what are the main symptoms of clostridium difficile? (affects bowel; colitis)

Answer 39

- watery diarrhoea (10-15 times a day) - abdominal cramps and pain - tachycardia (fast heart rate) - fever - blood and pus in stool - dehydration - anorexia (loss of appetite)

Question 40

What are the 3 main staphylococci?

Answer 40

1. staphylococcus aureus 2. staphylococcus epidermis 3. staphylococcus saprophyticus

Question 41

What does a positive coagulase test indicate?

Answer 41

Staphylococcus aureus

Question 42

What two bacteria are associated with negative coagulase test?

Answer 42

1. staphylococcus epidermis | 2. staphylococcus saprophyticus

Question 43

What does Staphylococcus epidermis cause?

Answer 43

Found everywhere on skin. May cause infection of catheters, prostheses and ventriculo-peritoneal shunts.

Question 44

What does Staphylococcus saprophyticus cause?

Answer 44

Cause of UTI in women of child bearing age.

Question 45

What does streptococcus pneumoniae cause?

Answer 45

- Normal flora in upper resp. tract. | - Commonest cause of bacterial lobar pneumonia. Major cause of meningitis in children and elderly. Vaccine available

Question 46

What does viridians streptococcus cause?

Answer 46

- Normal resident in mouth. | - Common cause of endocarditis, following dental treatment

Question 47

What is the spore forming, aerobic bacillus bacteria?

Answer 47

Bacillus Species

Question 48

What two groups are aerobic, spore-forming, bacillus species split into and what do they cause?

Answer 48

1. bacillus cereus (food poisoning) | 2. bacillus anthracis (anthrax)

Question 49

What are the 2 aerobic, non-spore forming bacilli?

Answer 49

1. listeria monocytogenes | 2. corynebacterium diphtheriae

Question 50

What does listeria monocytogenes cause? (aerobic non-spore forming bacilli)

Answer 50

- Found in animal and vegetable products (may be ingested). | - Cause menegitis in neonates and the elderly and bacteraemia in pregnancy

Question 51

What does corynebacterium diphtheriae cause?

Answer 51

Causes diphtheria and skin commensals

Question 52

What are the 4 anaerobic spore forming bacilli? "Please don't take brainscape"

Answer 52

1. clostridium difficile 2. clostridium perfringens 3. clostridium tetani 4. clostridium botulinum

Question 53

What does clostridium botulinum cause?

Answer 53

- Cause of botulism following ingestion of contaiminated food. - Produces most potent neurotoxin. Rare in UK.