Classification of Pathogenic Bacteria

Question 1

What are the two types of aerobic gram positive cocci?

Answer 1

Staphylococci (clusters)

Streptococci and enterococci (chains)

Question 2

What aerobic gram positive bacteria are clusters?

Answer 2

Staphylococci.

Question 3

What aerobic gram positive bacteria are chains?

Answer 3

Streptococci and enterococci.

Question 4

What test do staphylococci undertake?

Answer 4

Coagulase test.

Question 5

What does the coagulase test do?

Answer 5

Classifies staphylococci as positive or negative- they can be further isolated as MSSA/MRSA.

Question 6

What is an example of a positive coagulase staphylococci?

Answer 6

Staphylococcus aureus- major pathogen, commensal in nose, wide range from boils to septicaemia.

Question 7

What are staphylococcus aureus resistant to and why?

Answer 7

Penicillin due to production of penicillinase (B-lactamase).

Question 8

What more serious complication is seen in staphylococcus aureus?

Answer 8

Methicillin resistance- MRSA, becomes a major clinical issue for infection prevention and control in hospitals.

Question 9

What are examples of negative coagulase staphylococci?

Answer 9

S. epidermis, S. haemolytic, S. saprophytic, S, lugunensis, many commensals, form biofilms, pathogens in present of foreign objects.

Question 10

When do negative coagulase staphylococci often become pathogens?

Answer 10

In presence of foreign agents (e.g. foreign bodies/transplant).

Question 11

What structure are streptococci/enterococci?

Answer 11

Chained.

Question 12

What are the classifications of streptococci/enterococci?

Answer 12

Alpha-haemolytic
Beta-haemolytic
Non-haemolytic

Question 13

What do alpha-haemolytic streptococci do to blood agar?

Answer 13

Turn green.

Question 14

What do beta-haemolytic streptococci do to blood agar?

Answer 14

Turn clear.

Question 15

What streptococci is alpha-haemolytic?

Answer 15

Strep. pneumonia.

Question 16

What does Strep. pneumoniae do?

Answer 16

Pneumonia, meningitis, septicaemia.

Question 17

What are beta-haemolytic streptococci ordered by?

Answer 17

Type A-G.

Question 18

What streptococci is beta-haemolytic Type A?

Answer 18

Strep. pyogenes.

Question 19

What does Strep. pyogenes do?

Answer 19

Pharyngitis, meningitis, septicaemia.

Question 20

What is an anaerobic gram positive bacteria?

Answer 20

Clostridium difficle.

Question 21

What does C. difficle do?

Answer 21

Causes diarrhoea through toxin production- assymptomatic gut carriage.

Question 22

What are the types of gram negative pathogenic bacteria?

Answer 22

Aerobic- E.coli, Salmonella, Pseudomonas, Campylobacter spp, helicopter pylons, haemophilus influenzae.
Anaerobes- polymicrobial infection e.g. bacterioides.

Question 23

What does Escherichia coli. do?

Answer 23

Found in human/animal reserves, causes diarrhoea.

Many virulence mechanisms, ferment lactose.

Question 24

Does E. coli ferment lactose?

Answer 24

Yes.

Question 25

What does salmonella do?

Answer 25

Causes self-limiting enterocolitis, can invade bloodstream causing septicaemia, no fermentation of lactose.

Question 26

How does salmonella cause sepsis?

Answer 26

Invasion of bloodstream.

Question 27

Does salmonella ferment lactose?

Answer 27

No.

Question 28

What do pseudomonas do?

Answer 28

Soil/water coloniser, can contaminate medical equipment causing sepsis, feared pathogen in cystic fibrosis.

Question 29

How do pseudomonas cause sepsis?

Answer 29

Contamination of medical equipment.

Question 30

What are pseudomonas the feared pathogen in?

Answer 30

Cystic fibrosis.

Question 31

What do campylobacter spp. do?

Answer 31

Found in domestic animals/chickens, spread through faecal-oral route, cause foul-smelling bloody diarrhoea.

Question 32

How are campylobacter spp. spread?

Answer 32

Faecal-oral route from domestic animals/chickens.

Question 33

What do helicopter pylons do?

Answer 33

Damage mucus, cause gastrointestinal ulceration, curved rod shape and human stomach commensal.

Question 34

What do helicopter pylons increase the risk of?

Answer 34

Gastric adenocarcinoma.

Question 35

What shape are helicopter pylons?

Answer 35

Curved rods.

Question 36

What do haemophilia influenzae do?

Answer 36

Cause respiratory tract infection.

Question 37

What shape are haemophilia influenzae?

Answer 37

Mixed appearance.

Question 38

What are anaerobic gram negative bacteria an example of?

Answer 38

Polymicrobial infection.

Question 39

What are an example of gram negative anaerobes?

Answer 39

Bacterioides.

Question 40

What are 2 examples of bacterioides?

Answer 40

Prevotella. | Porphyromonas.