gram negative bacteria week 5

Question 1

what are the gram negative strict aerobic bacilli

Answer 1

• legionella sp.

- pseudomonas aeruginosa

Question 2

what are the gram negative aerobic cocci (diplococci)

Answer 2

• neisseria gonorrhoeae (gonorrhoea)

- nerisseria meningitidis (meningitis)

Question 3

what are the gram negative aerobic small bacilli

Answer 3

• bordetella pertussis (whooping cough)

- haemophilus influenzae (exacerbation COPD)

Question 4

what are the gram negative aerobic large bacilli which are gut commensals

Answer 4

• E. coli
• klebsiella sp.
• proteus sp.

Question 5

what are the gram negative aerobic large bacilli that are gut pathogens

Answer 5

• salmonella sp.
• shigella sp.
• E. coli O157

Question 6

what is the gram negative microaerophilic small curved bacilli

Answer 6

campylobacter sp.

Question 7

what is the gram negative microaerophilic spiral bacilli

Answer 7

helicobacter sp. (gastritis)

Question 8

what is the gram negative anaerobic bacilli

Answer 8

bactericides sp. (gut commensals)

- gram negative anaerobic cocci not relevant

Question 9

what are coliforms

Answer 9

organisms which are in the family enterobacteriaceae
- gram negative bacilli
mainly commensals of the large intestine

Question 10

what is a preliminary test to help classify gram negative bacilli

Answer 10

lactose fermentation

• e.g. salmonella does not ferment lactose
• e.g. E. coli ferments lactosse

Question 11

what is moraxella catarrhalis

Answer 11

• gram negative cocci

- causative agent of respiratory tract infections

Question 12

what is campylobacter spp.

Answer 12

• gram negative curved bacilli
• microaerophilic
  (likes low O2)
• source is domestic animals and chickens
• faecal-oral route
• commonest cause of bloody bacterial diarrhoea in UK

Question 13

what is helicobacter pylori

Answer 13

• gram negative bacteria
• spiral bacilli
• natural habitat is stomach
• damages mucosa and causes ulcers
• risk for gastric adenocarcinoma

Question 14

what is haemophilus influenzae

Answer 14

• gram negative
• cocco-bacilli (mixed appearance (although on diagram says small bacilli)
• causes respiratory tract infection

Question 15

what is a gram negative anaerobe

Answer 15

• often part of a polymicrobial infection
• able to live in the absence of oxygen
• bacteriodes spp.
• prevotella
• porphyromanas

Question 16

what is different about acid and alcohol fast bacilli (AAFB)

Answer 16

• miscellaneous bacteria
• resistant to decolorisation by acid or alcohol after staining with carbol fuchsin
• mycobacterium species are visualised with special stains e..g. ziehl-neelsen (ZN) or auramine

Question 17

how to identify mycobacterium in lab

Answer 17

ZN or auramine screening

- growth within 2-4 weeks in culture

Question 18

what is tuberculosis caused by

Answer 18

mycobacterium tuberculosis (miscellaneous bacteria)

Question 19

what is leprosy caused by

Answer 19

mycobacterium leprae

attacks peripheral nerves

Question 20

what are spirochaetes

Answer 20

• long, spiral shaped bacteria
• not easily visualised by light microscopy
• difficult to culture (never treponema palladium)
• dark ground microscopy or immunofluorescence
• often diagnosed by serology

Question 21

what is treponema pallidum and what does it cause

Answer 21

• spirochaete

- syphilis

Question 22

what is borrelia burgdorferi and what does it cause

Answer 22

• spirochaete

- lyme disease

Question 23

what causes chlamydia

Answer 23

chlamydia trachoma’s

- ophthalmic and genital tract infection

Question 24

what causes viral induced tumours

Answer 24

papillomaviruses - cervical carcinoma

retroviruses - lymphomas and leukaemias

Question 25

what is an example of a latent viral infection

Answer 25

herpes simplex virus 
cold sores (type 1)
genital lesions (type 2)