Bacterial Pathogens

Question 1

Types of bacteria

Answer 1

Gram +ve cocci
Gram +ve bacilli
Gram -ve coccobacilli
Gram -ve cocci
Gram -ve bacilli
Spiral bacteria

Question 2

Examples of gram +ve cocci

Answer 2

Staphylococcus aureus
Staphylococcus progenies
Staphylococcus agalactiae

Question 3

Examples of gram +ve bacilli

Answer 3

Bacillus anthracis
Clostridium difficile
Listeria monocytogenes
Corynebacterium diptheriae

Question 4

Examples of gram -ve coccobacilli

Answer 4

Haemophilus
Bordetella
Brucella
Pasteurella

Question 5

Examples of gram -ve cocci

Answer 5

Neisseria meningitidis

Neisseria gonorrhoeae

Question 6

Examples of gram -ve bacilli

Answer 6

Salmonella typhi
Shigella spp
Escherichia coli
Proteus spp
Yersinia pestis

Question 7

Examples of spiral bacteria

Answer 7

Helicobacter
Campylobacter
Borrielia
Leptospira
Treponema pallidum

Question 8

Gram positive

Answer 8

Does not have an outer membrane of lipopolysaccharide and protein

Question 9

Gram negative

Answer 9

Has an outer membrane of lipopolysaccharide and protein

Question 10

3 main factors for why certain bacteria cause certain infections

Answer 10

Host factors
Opportunity
Bacterial factors

Question 11

Examples of host factors

Answer 11

Devices

Immune system

Question 12

Examples of opportunity

Answer 12

Exposure

Normal flora

Question 13

Examples of bacterial factors

Answer 13

Virulence
Resistance
Environmental survival

Question 14

E. coli and UTIs

Answer 14

Part of normal bowel flora in most humans
Colonisation of urethral meatus and surrounding area (especially with shorter urethra in females)
Can adhere to both uroepithelial cells and urinary catheter materials
Triggers host inflammatory response
Able to develop antibiotic resistance

Question 15

S. aureus and skin infections

Answer 15

Carried in nose of up to 50% of people
Can adhere to damaged skin (e.g. eczema, surgical wound)
Produces damaging exoenzymes and provokes host response (e.g. pus formation)

Question 16

Possible complications fo S. aureus infection

Answer 16

Bacteraemia/septicaemia (especially)
Osteomyelitis/septic arthritis
Endocarditis
Pneumonia
UTI
Meningitis

Question 17

Staphylococcus epidermis

Answer 17

Opportunistic skin commensal bacterium
Causes infection in association with foreign bodies e.g. IV catheters, prosthetics
Can form a biofilm of glycocalyx (slime) on plastics/metals

Question 18

Streptococcus pyogenes overview

Answer 18

AKA Group A Strep

Most common cause of bacterial sore throat

Question 19

Other diseases caused by group A Strep

Answer 19

Scarlet Fever
Necrotising fasciitis
Other SSTIs
Invasive infections e.g. pneumonia
Puerperal sepsis
Secondary immunological presentations

Question 20

Streptococcus pneumoniae

Answer 20

Most common causes of bacterial pneumonia and bacteria meningitis (except in neonates)

Question 21

Streptococcus agalacticae

Answer 21

Group B Strep

Most common cause of bacterial meningitis and sepsis in neonates

Question 22

Streptococcus milleri complex

Answer 22

3 closely related pus-forming streptococci

Associated with abscesses - dental, lung, liver, brain etc.

Question 23

Viridans streptococci

Answer 23

Classic cause of sub-acute bacterial endocarditis

Usually only pathogenic if there is an underlying heart condition e.g. aortic stenosis, mitral regurgitation

Question 24

Streptococcus gallolyticus

Answer 24

Part of bowel flora

Can be associated withcolonic malignancies

Question 25

Listeria monocytogenes

Answer 25

Rare but significant cause of sepsis and meningitis in pregnancy, neonates and immunosuppressed patients Associated with unpasteurised dairy

Question 26

Corynebacterium species

Answer 26

Opportunistic associated with devices and trauma Classic diphtheria cause Rarely now seen in UK due to vaccines

Question 27

Propionibacterium acnes

Answer 27

Associated with acne | Also called Cutibacterium acnes

Question 28

Enterobacteriaceae

Answer 28

Collective term for gram -ve bacilli found in bowel flora

Question 29

E. coli

Answer 29

Most common cause of UTI and bacteraemia | Toxigenic strains associated with severe diarrhoea and haemolytic uraemia syndrome

Question 30

Pseudomonas aeruginosa

Answer 30

Multi-resistent gram -ve Opportunistic - causes infection in vulnerable patients Can cause respiratory infections, UTIs, soft tissue etc. Often produces characteristic green pigment

Question 31

Neisseria meningitidis

Answer 31

Causes meningococcal sepsis and/or meningitis Classic presentation is non-blanching rash Reduction in case since vaccination

Question 32

Neisseria gonnorhoeae

Answer 32

Cause of gonorrhoea Can cause conjunctivitis as a result of vertical transmission Can rarely cause secondary invasive infections

Question 33

Haemophilius influenzae

Answer 33

Normal respiratory flora but can cause respiratory infections Capsulated types associated with meningitis and epiglottitis

Question 34

Anaerobes

Answer 34

``` The Clostridium Bunch C. difficile - diarrhoea/colitis C. perfringens - gas gangrene C. tetani - tetanus C. botulinum - botulism Other species too ```

Question 35

Mycobacterium

Answer 35

AFBs - no gram staining M. tuberculosis causes TB Can cause a range of other infections including opportunistic in immunocompromised patients

Question 36

Bacteria without conventional cell wall

Answer 36

Chalmydia species | Mycoplasma species

Question 37

Spirochaetes

Answer 37

Treponema pallidum which causes syphilis | Other spirochaetes can cause leptospirosis or Lyme disease