Classification of Pathogenic Bacteria

Question 1

How do bacteria reproduce

Answer 1

Mainly by binary fission

Question 2

Is cocci rod shaped or circular

Answer 2

Circular

Question 3

Is bacilli rod shaped or circular

Answer 3

Rod shaped

Question 4

Is staphylococci in clusters or chains

Answer 4

Clusters

Question 5

Is streptococci in clusters or chains

Answer 5

Chains

Question 6

What does a positive coagulase test mean

Answer 6

Staphylococcus aureus is present which may indidicate MSSA or MRSA

Question 7

What is Staphylococcus aureus

Answer 7

A major human pathogen carried in the nose, axilla and perineum

Question 8

What can Staphlyococcus aureus cause

Answer 8

Wide range of diseases
Boils/abscesses
Soft tissue infections
Septicaemia 
Osteomyelitis

Question 9

What is Staphylococcus aureus commonly resistant to and why

Answer 9

Penicillin
Due to the production of penicillinase however using a different mechanism can produce strains which are methicillin resistant

Question 10

What does a negative coagulase test indicate

Answer 10

Many different species such as:
S. epidemidis 
S. haemolyticus 
S. saprophyticus
S. lugdunenis

Question 11

What are the categories of Streptococcus

Answer 11

α-haemolytic (partial haemolysis) which turns blood agar green
β-haemolytic (complete haemolysis) which turns blood agar clear
non haemolytic

Question 12

Give an example of an α-haemolytic streptococci and what it can cause

Answer 12

Streptococcus pneumoniae which causes pneumonia, meningitis and septicaemia

Question 13

How can β-haemolytic streptococci be further identified

Answer 13

Through carbohydrate surface antigens which are split into groups A-G

The clinically most important groups are A, B, F and D

Question 14

How are gram positive bacilli able to grow

Answer 14

Aerobically

Anaerobically

Question 15

Give an example of a group A streptococci

Answer 15

Streptococcus pyogenes which is a major pathogen causing pharyngitis, cellulitis and necrotising fasciitis (‘flesh eating bug’)

Question 16

What is an important cause of diarrhoea that is which is associated with toxin production and can be potentially fatal

Answer 16

Clostridium difficile which is difficult to culture and asymptomatic when carried in the gut of healthly people

Question 17

What increases the risk of obtaining Clostridium difficile

Answer 17

Antibiotics

Anything which disrupts the normal gut flora

Question 18

How can Clostridium difficile spread

Answer 18

Spores

Question 19

How is Clostridium difficile detected

Answer 19

Using its antigens and toxins in stool samples by ELISA.

Question 20

Name 2 Gram negative cocci

Answer 20

Neisseriac spp.

Moraxella spp.

Question 21

What is meningitis

Answer 21

Inflammation of the meninges and septicaemia

Question 22

What does Neisseria meningitidis cause and how can it be identified

Answer 22

Meningitis which is the inflammation of the meninges and septicaemia.

PCR can be used on EDTA blood

Question 23

What does Neisseria gonorrhoeae cause and how is it spread

Answer 23

Urethritis in men
Pelvic inflammation disease in women
Sexual contact

Question 24

What does Moraxella catarrhalis act as the causative agent for

Answer 24

Respiratory tract infections especially in those with underlying lung pathology.

Question 25

What are coliforms

Answer 25

Organisms which are in the Enterobacteriaceae family

Question 26

Where are coliforms mainly found

Answer 26

Human large intestine

Question 27

What is a useful test to identify Gram negative bacteria

Answer 27

Lactose fermentation is useful as a preliminary test

Question 28

What are the virulance factors for E. coli

Answer 28

Pili Capsule Endotoxin Exotoxins

Question 29

Where can E. coli be found

Answer 29

Human and animal reservoirs

Question 30

What does E. coli ferment

Answer 30

Lactose

Question 31

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

Answer 31

Over 160 | Based on O antigen (LPS)

Question 32

What can E. coli cause

Answer 32

UTI's

Question 33

Name two types of E. coli

Answer 33

Enterotoxogenic | Enterohaemorrhagic

Question 34

What can enterohaemorrhagic cause

Answer 34

Bloody diarrhoea | Haemolytic uraemic syndrome (HUS) which is associated with E. coli O157

Question 35

What can enterotoxogenic cause

Answer 35

A common cause of traveller's diarrhoea

Question 36

Can the Salmonella spp. ferment lactose

Answer 36

No

Question 37

What can the Salmonella spp. cause

Answer 37

Self-limiting enterocolitis with or without bloody diarrhoea It has an incubation period of 12-48 hours

Question 38

Can Salmonella enter the bloodstream

Answer 38

Yes

Question 39

What can Salmonella typhi cause and what are its symptoms

Answer 39

Typhoid fever Symtoms include: Fever Constipation in the early stages

Question 40

Where can Salmonella typhi be isolated from

Answer 40

Blood cultures | Faeces

Question 41

Name 3 coliforms

Answer 41

Shigella spp Klebsiella spp Proteus spp

Question 42

Is E. coli a coliform

Answer 42

Yes

Question 43

How does the Campylobacter spp grow

Answer 43

In the presence of low oxygen

Question 44

What is the source of Campylobacter

Answer 44

Domestic animals e.g. Chickens

Question 45

How can Campylobacter be transmitted

Answer 45

Faecal-oral route (incubation period of 2-5 days)

Question 46

What can Campylobacter cause

Answer 46

Foul smelling then bloody diarrhoea

Question 47

What type of bacteria is Campylobacter

Answer 47

Curved Gram negative bacilli

Question 48

What type of bacteria is Helicobacter pylori

Answer 48

Curved Gram negative bacilli

Question 49

What is Helicobacter pylori's natural habitat

Answer 49

Human stomach

Question 50

What can Helicobacter do

Answer 50

Damage mucosa Cause ulcers A strong risk factor for gastric adenocarcinoma

Question 51

What does the Haemohilus influenzae virus appear as

Answer 51

Cocco-bacilli

Question 52

What can the Haemohilus influenzae virus cause

Answer 52

Respiratory tract infections

Question 53

What can the capsulate form (type b) of Haemohilus influenzae cause

Answer 53

Meningitis in children

Question 54

Where can Pseudomonas colonise

Answer 54

Water and soil | e.g. drains, sinks, mops

Question 55

What type of nosocomial infection can Pseudomonas cause

Answer 55

Sepsis (e.g. UTI, bacteramia, pneumonia)

Question 56

How can the Pseudomonas spp be treated

Answer 56

Has limited treatment options as it has multi-drug resistance mechanisms

Question 57

What are anaerobes normally a part off

Answer 57

Polymicrobial infection

Question 58

Name some anaerobes

Answer 58

Bacteriodes spp. Prevotella Porphyromonas

Question 59

Describe Bacteroides fragilis

Answer 59

Part of normal colonic flora Can cause intra-abdominal abscess May spread to other sites

Question 60

What do oral anaerobes have a role in

Answer 60

Aspiration pneumonia | Human and animal bite infections

Question 61

Can all bacteria be Gram stained

Answer 61

No

Question 62

Give examples of bacteria which cannot be Gram stained

Answer 62

Mycobacterium spp. Spirochaetes. Chlamydia

Question 63

What is acid and alcohol fast bacilli (AAFB)

Answer 63

This type of bacilli are resistant to decolourisation by acid or alcohol once it has been stained with carbol fuchsin

Question 64

How can Mycobacterium be visualised

Answer 64

Using Ziehl-Neelsen staining Auramine staining This does do help identify the species

Question 65

How can a Mycobacterium species be identified

Answer 65

Culture | The new automated liquid culture allows growth to occur within 2-4 weeks.

Question 66

What causes TB

Answer 66

Mycobacterium tuberculosis

Question 67

When is rapid diagnostic nucleic acid amplification tests recommended for pulmonary TB diagnosis

Answer 67

When TB is suspected in a HIV positive patient When rapid information about the mycobacterial species would alter a persons care When a large contact tracing initiative is being explored

Question 68

What can Mycobacterium leprae cause

Answer 68

Leprosy

Question 69

Can Mycobacterium leprae be cultured

Answer 69

No

Question 70

What are spirochaetes

Answer 70

Long, spiral shaped bacteria

Question 71

How can spirochaetes be visualised

Answer 71

Not very well with light microscopy but can be seen with immunofluorescence

Question 72

Name some spirochaete diseases

Answer 72

Syphilis caused by Treponema pallidum Lyme disease caused by Borrelia burgdorferi Leptospirosis caused by Leptospira interrogans

Question 73

What is primary syphilis

Answer 73

Non-painful skin lesions (chancre) at the site of infection, usually the skin or mucous membranes

Question 74

What is secondary syphilis

Answer 74

Occurs 6-8 weeks after the primary symptoms causing generalised systemic illness and rash

Question 75

What is tertiary syphilis

Answer 75

Can occur years after the primary symptoms and affects the CNS

Question 76

How can syphilis be diagnosed

Answer 76

Serology | Nucleic acid amplification tests

Question 77

What is Chlamydia

Answer 77

An obligate intracellular bacteria that can only be cultured in cell lines

Question 78

What type of chlamydia causes genital tract infections

Answer 78

Chlamydia trachomatis

Question 79

How can Chlamydia trachomatis be diagnosed

Answer 79

Using NAAT on the first void urine or vulval/vaginal swabs