Bacterial Pathogens

Question 1

Staphylococcus aureus - key facts?

Answer 1

Mostly found in nasal carriage, causes skin and soft tissue infections.

Question 2

What type of staphylococci is S. epidermidis?

Answer 2

coagulase negative

Question 3

Where does S. Epidermis live and what does it cause?

Answer 3

Lives in skin and causes infection in association with ‘foreign bodies’ e.g. catheters.
Adheres via glycocalyx.

Question 4

What is the other name for streptococcus pyogenes?

Answer 4

Group A Strep.

Question 5

What do group A strep/ streptococcus pyogenes cause?

Answer 5

Sore throat. (also scarlet fever, necrotisig fasciitis, SSTI’s of skin, puerperal sepsis).

Question 6

What does streptococcus pneumoniae cause?

Answer 6

Commonest cause of bacterial pneumonia. Commonest cause of bacterial meningitis (except in neonates). Can cause other childhood infection e.g. otitis media.

Question 7

What is the other name for Streptococcus agalactiae?

Answer 7

Group B strep.

Question 8

What does Streptococcus galactiae cause?

Answer 8

Commonest cause of bacterial meningitis in neonates (<3months).

Question 9

What is the Streptococcus milleri complex?

Answer 9

3 closely related species of pus-forming streptococci. Associated with abscesses (dental, brain, lung, liver).

Question 10

What are Viridans Streptococci and where do they live?

Answer 10

Collective name for a-haemolytic streptococci that inhabit the upper respiratory tract e.g. S. oralis, S. mitis.

Question 11

What was Streptococcus Gallocyticus formerly known as and what is it?

Answer 11

Streptococcus bovis- a type - a-haemolytic streptococcus that forms part of bowel flora. Associated with colonic malignancies.

Question 12

What is Listeria monocytogenes?

Answer 12

A gram positive bacillus whih is rare but signif cause of sepsis & meningitis in pregnancy, neonates & immunosuppressed patients.

Question 13

What particular features does listeria monocytogenes possess?

Answer 13

Zoonosis (passed from humans to animals) and able to grow at low temps. Associated with consumption of unpasteurised dairy products.

Question 14

What is Cornebacterium species and where does it live?

Answer 14

Gram positive bacilli, live in skin and URT.

Question 15

What are corynebacterium associated with?

Answer 15

1. Oppurtinistic infections associated w/ devices & trauma 2. Coonebacterium diptheria (rare as now have vaccines).

Question 16

What is propionibacterium acnes?

Answer 16

Gram positive bacillus associated with acne. Can also cause device-associated infections.

Question 17

What are enterobacheriaceae ‘coliforms’?

Answer 17

Collective term for gran negative bacilli found in bowel flora.

Question 18

What does E. coli cause?

Answer 18

Commonest cause of UTI, Commonest cause of bacteraemia (urinary bialy & intr-abdo). Causes nosocomial infections. Toxigenic strain (e.g. O157) associated with severe diarrhoea and haemolytic uraemic syndrome (HUS).

Question 19

What is Pseudomonas Aeruginosa

Answer 19

Multi-resistant gram negative bacillus. Can cause rest infection, UTI’s, skin & soft tissue infections. Often produces characteristic green pigment.

Question 20

What is Neisseria meningitidis

Answer 20

It is a gram negative diplococcus which causes meningococcal sepsis and/or meningitis.

Question 21

What is classic presentation of neisseria meningitidis?

Answer 21

Purpuris non-blanching rash (sepsis)

Question 22

What is Neisseria gonorrhoeae?

Answer 22

Gram negative diplococci causeding gonorrhea, opthalmia neonatorum. Occasionally can cause invasive infections e.g. septic arthritis.

Question 23

What is Haemophilus influenzae?

Answer 23

Gram negative bacillus which forms part of normal RT flora BUT can cause RTI’s e.g. pneumonia, infective exacerbations of COPD.

Question 24

What are capsulated types (e.g. type b). of haemophilia influenzae associated with?

Answer 24

Meningitis and epiglottis. (only type b infections prevented by Hlb vaccine).

Question 25

What are enterococci?

Answer 25

gram-positive cocci that tend to occur in pairs -> diplococci

Question 26

What are HACEK organisms?

Answer 26

Group of gram negative bacteria e.g. haemophilus initially thought to be cause of infective endocarditis - now known as rare cause.

Question 27

What do spirochetes cause?

Answer 27

Treponema pallidum causes syphilis. Other species cause leptospirosis and Lyme Disease.

Question 28

What are three bacterium without conventional cell wall?

Answer 28

1. Chlaymdia species - C. trachoma’s = commonest cause of STI.
2. Mycoplasma species - M. pneumonia = commonest cause of RTI’s/ and
3. Legionella pneumophila causing Legionnaire’s.

Question 29

What are examples of anaerobes?

Answer 29

Clostridium species (Spore-forming), bacterioides species, Fusobacerium species, Prevotella species and others. Often part of polybacterial infections e.g. dental, absecesses, skin etc

Question 30

What does C. difficile cause?

Answer 30

antibiotic-related diarrhoea/colitis

Question 31

What does C. perfringens cause?

Answer 31

classical cause of gas gangrene.

Question 32

What does C. tetani cause?

Answer 32

tetanus

Question 33

What does C. botulinum cause?

Answer 33

Botulism.

Question 34

What are Mycobacterium species often referred to as?

Answer 34

Acid Fast Bacillis (as they do not stain using conventional gram staining)

Question 35

What does mycobacterium tuberculosis cause?

Answer 35

tuberculosis.

Question 36

What do Atypical Mycobacteria cause?

Answer 36

Resp infections in those with chronic lung disease, in immunocompromised patients e.g. AIDS, transplant.