Gram Positive or Negative?

Question 1

Causative organism of Enteric fevers

Answer 1

Salmonella enterica serotype typhi (paratyphi)

Question 2

Describe appearance of Salmonella enterica on microscopic examinations

Answer 2

Gram-negative Bacillus
Pale colonies (lactose-negative) on MacConkey's agar

Question 3

Causative organism of Gastritis/Duodenal Ulceration

Answer 3

Helicobacter pylori

Question 4

Describe appearance of Helicobacter pylori on microscopic examinations

Answer 4

Gram-negative spiral bacillus

Microaerophilic and strongly urease-positive

Question 5

Causes of diarrhoea

Answer 5

Bacteria
Antibiotics
Viral
Protozoal
Food poisoning

Question 6

Bacterial causes of diarrhoea

Answer 6

Escherichia coli (ETEC and VTEC)
Vibrio cholerae
Shigella sonnei (dysenteriae)

Question 7

What is ETEC and VTEC

Answer 7

Enterotoxigenic Escherichia coli

Verotoxigenic E. coli

Question 8

Describe appearance of Escherichia coli on microscopic examinations

Answer 8

Gram-negative bacillus

Lactose-positive (red colonies) on MacConkeys agar

Question 9

Describe appearance of Vibrio cholerae on microscopic examinations

Answer 9

Gram-negative rods

Question 10

Describe appearance of Shigella sonnei on microscopic examinations

Answer 10

Gram-negative bacillus

Lactose-negative on MacConkeys agar (pale colonies)

Question 11

Protozoal causes of diarrhoea

Answer 11

Cryptosporidium

Giardia

Question 12

Viral causes of diarrhoea

Answer 12

Rotavirus

SRSV (norovirus)

Question 13

Antibiotic-associated causes of diarrhoea

Answer 13

Clostridium difficile
Staphylococcus aureus
Candida albicans

Question 14

Microbiological causes of food poisoning and thus diarrhoea

Answer 14

Slamonella
Camylobacter
Clostridium perfringens
Bacillus cereus
Staphylococcus aureus

Question 15

Describe appearance of Campylobacter jejuni on microscopic examinations

Answer 15

Gram-negative (spirally curved) bacillus

Question 16

What is Cryptosporidium parvum and what stain is used is show it

Answer 16

Protozoan

Ziehl-Neelsen stain

Question 17

Incubation period of Cryptosporidium

Answer 17

4-14 days

Question 18

Diameter of rotavirus

Answer 18

70mm (wheel-like shape seen by electron microscopy)

Question 19

Incubation period of rotavirus

Answer 19

1-7 days

Question 20

Incubation period of salmonella spp. and related foods

Answer 20

16-48 hours

Poultry, eggs

Question 21

Incubation period of campylobacter spp and related foods

Answer 21

24-72 hours

Meat products

Question 22

Incubation period of Clostridium perfringens

Answer 22

12-24 hours

Cooked meats

Question 23

Incubation period of Staphylococcus aureus

Answer 23

1-6 hours

Finger food

Question 24

Incubation period of Bacillus cereus

Answer 24

1-6 hours

Rice

Question 25

Symptoms of salmonella spp

Answer 25

Diarrhoea | Some abdominal pain

Question 26

Symptoms of Campylobacter spp

Answer 26

Profuse diarrhoea | Sever abdominal pain

Question 27

Symptoms of Clostridium perfringens

Answer 27

Colicky abdominal pain | Diarrhoea

Question 28

Symptoms of staphylococcus aureus

Answer 28

Severe vomiting | Fever

Question 29

Symptoms of Bacillus cereus

Answer 29

Profuse vomiting

Question 30

How to diagnose Streptococcus pneumoniae

Answer 30

``` Gram positive Cocci Aerobic Chains Catalase positive Alpha-haemolytic Optochin positive ```

Question 31

Diagnose Staphylococcus aureus

Answer 31

``` Gram positive cocci Aerobic Clusters Catalase negative Coagulase positive ```

Question 32

Diagnose Neisseria

Answer 32

Gram Negative cocci

Question 33

Diagnose Strep. viridans

Answer 33

``` Gram positive Cocci Aerobic Chains Catalase positive Alpha-haemolytic Optochin negative ```

Question 34

Stain used to identify Mycobacteria

Answer 34

Ziehl-Neelsen stain | Acid fast positive

Question 35

Diagnosis of Mycob. tuberculosis

Answer 35

Rods Ziehl-Neelsen/Acid fast positive MTB complex

Question 36

Diagnose Escherichia (coli)

Answer 36

Rods Gram-negative Aerobic Lactose fermenters

Question 37

What other bacteria is diagnosed the same way as Escherichia in the lab

Answer 37

Klebsiella

Question 38

Diagnose Listeria or Corynebacterium

Answer 38

Rods Gram-positive Aerobic

Question 39

Diagnose salmonella

Answer 39

Rods Gram-negative Aerobic Non fermenter

Question 40

Diagnose Enterococcus

Answer 40

``` Cocci Gram positive Aerobic Chains Streptococcus (catalase positive) Non-haemolytic (Group D) ```

Question 41

Other bacteria diagnosed the same way as enterococcus

Answer 41

Streptococcus bovis

Question 42

Diagnose Shigella

Answer 42

``` Same as salmonella: Rods Gram-negative Aerobic Non fermenter ```

Question 43

Diagnose Strep pyogenes

Answer 43

``` Cocci Gram-positive Aerobic Chains (Strep - catalase positive) Beta haemolytic Group A ```

Question 44

Diagnose Staph epidermis

Answer 44

``` Cocci Gram positive Aerobic Clusters (staph - catalase negative) Coagulase negative ```

Question 45

Diagnose pseudomonas

Answer 45

``` Rods Gram negative Aerobic Non-fermenters Oxidase positive ```

Question 46

Diagnose Clostridium

Answer 46

Rods Gram-positive Anaerobic

Question 47

Diagnose Strep agalactiae

Answer 47

``` Cocci Gram positive Aerobic Chains (strep - catalase positive) Beta haemolytic Group B ```

Question 48

Examples of Gram-negative rods (aerobic) that are neither lactose or non-lactose fermenters

Answer 48

``` Vibrio Campylobacter Helicobacter Haemophilus Legionella ```