1. MICROBIOLOGY
Chris Keil – F2

2. You are not alone Are there strong/powerful antibiotics?
A lot of testing is with chromatography – the future will be genetic
Apologies for pronunciation/mnemonics
Cover gram positive/negatives and TB/quiz if time

3. REferences For treatment – BNF guidelines
Microbiology and ID the basics – classification/treatment/everything you need to know
When you are an FY1 – microbiology guidelines
I won’t giving out the powerpoint – use the microbiology pdf – I will this!

5. Shapes – draw each one with your hand
COCCI
BACILLI
VIBRIO
SPIROCHAETE

6. COCCI – ANY GENERALLY ROUND SHAPED BACETERIA

7. Bacilli – rod shaped

8. Vibrio – curved red/comma shaped – “VIBRONS”

9. SPIROCHAETE - spirals

10. Why do I need to know about staining?
Is it clinically relevant for working as an FY1?
It comes up in exams
The future will be genetic testing – the culture will be important for growth but less so in identification and sensitivities
Help you navigate the branches of different bacteria

11. Different tests You should be aware of… 2 types of staining
2 types of agar
1 type of grouping

12. Gram staining – 2 broad groups + poorly staining
Named after Hans Christian Gram
Why do Gram staining? How many ways are there to slice a cake?
POSITIVE – PURPLE
NEGATIVE - RED

13. Gram Positive
Gram Negative
Other

14. Another type of staining
Ziehl Neelsen Staining
USED FOR MYCOBACTERIA
THEY ARE ACID FAST – PINK/RED
What does acid fast mean?
THIS MEANS THAT THEY RESIST ACID DE-COLOURISATION PROCEDURES

15. Specific tests
Gram Positive

16. CATALASE TESTS Gram positive cocci TELLS YOU THE DIFFERENCE BETWEEN:
STAPHYLOCOCCI
STREPTOCOCCI/ENTEROCOCCI
staphylococci use catalase to protect against hydrogen peroxide – reaction you see bubbles – catalase positive
if not present there is no reaction – catalase negative
23 seconds

17. Gram Positive Cocci
Staphylococcus
Strep/enterococcus

18. Coagulase positive Staphylococcus Used to differentiate between:
Staphylococcus aureus
Other Staphylococci
COAGULASE is an enzyme that causes coagulation – fibrin to clot
BACTERIA + PLASMA = CLOT - STAPH AUREUS – coagulase positive
BACTERIA + PLASMA = NO CLOT – OTHER STAPH SPEICES – coagulase negative
1 minute 6 seconds

19. Staphylococcus
S. Aureus
Other Staphylococci

20. Oxidase test
Identifies bacteria that are oxidase positive – produce cytochrome oxidase
Pseudomonas
Neisseria
POSITIVE TEST RESULT – BLACK/PURPLE COLOUR
NEGATIVE TEST RESULT – NO COLOUR CHANGE
25 seconds

21. Alpha haemolytic strep
Optochin test
Differentiates:
Streptococcus pneumoniae – what type of cocci…
Diplococci in chains
From other alpha haemolytic streptococci
Clear zone of lysis – strep. pneumoniae
Alpha haemolytic strep

22. Agars

23. Blood agar Streptococci Differentiates Alpha haemolytic streptococci
Beta haemolytic streptococci
Alpha – green pigment
Beta – clear zones of lysis
Non-haemolytic – no change
Streptococci

24. Macconkey agar – bile salts, lactose, ph indicator
Enterobacteria/bacilli
Bile salts only permit the growth of enteric bacteria
Lactose fermentation causes an acidic environment – red/pink colour change with the indicator
Red/pink colony – E Coli, Klebsiella
Clear colony – Salmonella, Shigella, Pseudomonas

25. Lancefield grouping
Differeniates beta haemolytic streptococci by detecting surface antigens:
Lots of groups
Group A Strep – pyogenes
Group B Strep - neonates

29. Toxins
Exotoxin – secreted by bacteria (MAINLY GRAM POSITIVE) – specific actions – like paralysis with botulinum toxin
Endotoxin – released when bacteria is damaged, less specific action – septic shock

30. Gram positive Sexy Streptococcus spp Students Staphylococcal spp
Can Corynebacterium spp AEROBIC
Diphtheria
Look Listeria spp
Listeria monocytogenes – non-pasteurised/those with contact with animals – farmers/vets!
Bad Bacillus spp. – go to which type of restaurant
Anthracis
Cereus – reheated rice – in exams – Chinese restaurant
Come morning Clostridium spp ANAEROBIC

31. GRAM negative Cocci Neisseria Moraxella catarrhalis – which condition?
Meningitidis – what type of cocci?
Diplococci
Gonorrhoea
Moraxella catarrhalis – which condition?
COPD

32. Gram negative bacilli ANAEROBES Bacteroides fragilis – causes…
90% of anaerobic peritoneal infections
All the others are aerobes

33. Gram negative bacteria – aerobic bacilli
Division by growth requirements
MacConkey agar – lactose fermenters - ?properties
E coli – causes
gastroenteritis/UTI
Klebsiella – causes
Pneumonia/UTI
Non lactose fermenters – MacConkey pale
Salmonella – causes
Typhoid, diarrhoea
Shigella – causes
diarrhoea in MSM (dysentery)
Proteus – causes
UTI

34. Gram negative aerobic bacteria - other
Pseudomonas Aeroginosa – causes
COPD and cystic fibrosis
Nosocomial infections
Vibro cholerae – where?
4 star rating on trip advisor

35. Other gram negative aerobic bacilli
Fastidious growth requirements – complex
Haemophilus Influenza – Harry Potter
(IECOPD)
Bordatella pertussis – Bought
(Whooping cough)
Legionella pneumophilia – Lots of
(Legionella – hotels/air conditioning)
Brucella – Big
(Brucellosis – unpasteurised milk)
Campylobacter – Cookies for
(diarrhoea/GBS)
Helicobacter Pylori – Hagrid
(ulcers)

36. Other – poorly gram staining
• Chlamydia spp. - CRUNCHY
Psittaci – birds
Trachomatis - chlamydia
• Coxiella spp. - CARROTS
Q fever
• Mycobacteria spp. - MAKE
TB, leprae
• Treponema spp. – THE
spirochaete - syphillis
• Borrelia spp. - BEST
Lyme disease
• Leptospira spp. - LIGHT
leptospirosis (water and livestock –farmer)
• Mycoplasma spp. – MEAL FOR
mycoplasma pneumoniae
• Rickettsia spp. - RABBITS
typhus (not typhoid!) spread by ticks

37. Tuberculosis
1/3 of the world’s population is thought to be infected with TB!!!
Treatment – 4 antibiotics - RIPE
Rifampicin - RED urine, hepatotoxicity
Isoniazid – peripheral neuropathy – N for neuropathy
Pyrizinamide - hepatotoxicity
Ethambutol – ocular/EYE toxicity

38. Urinary tract - UTI Most common causative organism… E Coli
Other causative organisms
Proteus
Klebsiella
First line
Trimethoprim/nitrofurantoin
Or amoxicillin

39. Pyelonephritis Most common causative organism: E Coli
Other causative organism
Enterococcus faecalis
Treatment
Use cefuroxime or quinolone (floxacin – ciprofloxacin)
Gentamicin

40. Prostatitis Most common causative organism E Coli But also
Proteus Mirabilis
Klebsiella
Antibiotic
Quinolones (ciprofloxacin)

41. SKIN - Impetigo
Most common organism
S Aureus
Treatment
Fusidic acid

42. CEllulitis
Common organism
S Aureus
Management
Flucloxacillin

43. RESPIRATORY - PNEUMONIA
Most common cause
Strep Pneumonia
Other causes
H Influenzae
Atypicals –
Coxiella, Chlamydophilia, Mycoplasma, Leigionella
Management – depends on severity calculated using the CURB65

44. CAP/HAP CAP Low severity Amoxicillin Moderate High severity
Benzylpenicillin + clarithromycin (why clarithromycin?)
HAP – broad spectrum
Co-amoxiclav – if early onset (less than 5 days into admission)
Tazoin – if late onset (more than 5 days)

45. MSK - Osteomyelitis Common organism S Aureus Other Enterocbacter
Streptococcus
Bonus point – if sickle cell anaemia
Salmonella
Management
Flucloxacillin

46. Septic arthritis Common organism S Aureus Other Streptococci
Neisseria – in sexually active young adults
Management
Flucloxacillin

47. Eye Common organism S Aureus Other causes Streptococci Haemophilus
Treatment
Chloramphenicol

48. GASTRO infections – C Diff
Treatment
Metronidazole – use in situations where anaerobic bacteria are suspected

49. CNS - meningitis Treatment depends on causative organism 2 most common
Neisseria Meningitidis
Streptococcus Pneumoniae
When unknown
3 months -50 years
Cefotaxime
Over 50 years
Cefotaxime and amoxicillin

50. Other typical exam characteristics
Listeria monocytogenes – causing listerosis (CNS infections and sepsis in immunocompromised)
- Grows in hot or cold temperatures
Cold – spread by PO route and growth not prevented by refrigeration
Cholera causes what type of diarrhoea
Rice water
Which infection causes bovine cough
Croup
Which infection causes paroxysmal coughing
Whooping cough

51. Other typical exam characteristics
White or grey discharge/fishy smell
Bacterial vaginosis – itching is uncommon
Yellow, green, frothy and itchy
Trichomonas

52. Questions