1. James Clayton Consultant Microbiologist
Antibiotics
James Clayton
Consultant Microbiologist

2. Antibiotic groups β-Lactams Penicillins
Penicillin, Amoxicillin, Flucloxacillin PO/IV
Penicillins + β-lactamase inhibitor
Co-amoxiclav (Amoxicillin + clavulanate) PO/IV
Tazocin (Piperacillin + tazobactam) IV
Cephalosporins PO/IV
Carbapenems
Meropenem, Ertapenem IV

3. Other antibiotics: Aminoglycosides Macrolides Glycopeptides
Gentamicin, (Amikacin) IV
Macrolides
Erythromycin, Clarithromycin PO/IV
Glycopeptides
Vancomycin, (Teicoplanin) IV
Tetracyclines
Doxycycline PO
Others
Trimethoprim, Nitrofurantoin PO
Rifampicin, Clindamycin PO/IV
Ciprofloxacin PO

9. Streptococci Group A streptococci Group B streptococci
Skin & soft tissue infection
Necrotising fasciitis
Tonsillitis
Toxic shock, sepsis
Group B streptococci
Neonatal infection, UTI
Other streptococci
Endocarditis, abscess

10. Streptococci & Enterococci
Strep. pneumoniae
URTI, pneumonia
Enterococcus faecalis / E.faecium
UTI, endocarditis

11. Staphylococcus Staph. aureus Skin & soft tissue infection Abscess
Bone & joint infection
Line infections
Severe pneumonia
Remember MRSA
(Meticillin resistant S.aureus)

12. E.coli & coliforms E.coli, Klebsiella, Proteus UTIs
Intra-abdominal infection
E.g. cholangitis, sepsis
Hospital-acquired infection
Remember ESBLs

13. Neisseria & Haemophilus
N. meningitidis
Meningitis
N. gonorrhoeae
Gonorrhoea
H. influenzae
Respiratory tract infection
Meningitis (rare)

14. Pseudomonas Anaerobes P. aeruginosa
UTIs (usually complicated / catheter)
Hospital acquired infections
Anaerobes
Intra-abdominal infections
Skin & soft tissue infections
Abscess

15. 7 cases

16. Case 1 John, 18 yrs old Sore throat for 2 days, feverish
Exudate on tonsils when examined by GP
Tonsillitis diagnosed.
What organisms cause tonsillitis?
What antibiotics are appropriate?

20. Coventry and Warwickshire Community Antibiotic Guidelines

21. Tonsillitis Majority caused by Group A streptococci
Penicillin susceptibility ~ 100%
Erythromycin susceptibility ~ 80%
Penicillin preferred to Amoxicillin as:
Narrower spectrum
EBV / glandular fever reaction
Oral antibiotics in a community setting

22. Case 2 Bob, 70 years old CXR – extensive consolidation CURB-65 = 2
COPD. 60 pack year smoking history.
Retired engineer.
3 day history of cough, green sputum, malaise, raised temperature
o/e crepitations, reduced air entry
CXR – extensive consolidation
CURB-65 = 2
No allergies

23. And Atypicals!

26. Coventry and Warwickshire Treatment Guidelines (Hospital)

27. Community acquired pneumonia
Strep. pneumoniae ~ %
Haemophilus influenzae ~ %
Staph. aureus ~ %
Severity of infection (CURB-65 score)
Determines need for IV or oral treatment
Determines need for broad vs narrow cover

28. Don’t forget atypicals in CAP!
Legionella pneumophila ~ 1 - 5%
Mycoplasma pneumoniae ~ %
Chlamydophila pneumoniae < 10% ?
Chlamydia psittaci, Coxiella < 2%
Viruses including Influenza < 15%
Addition of
Macrolide e.g. erythromycin or clarithromycin
Tetracycline e.g. doxycycline
(Ciprofloxacin)

29. Case 3
Katie, 25 years old
Presents to A&E with history of dysuria, frequency
Previously well

31. Do all antibiotics get into urine?
These do:
These don’t:
Penicillins (most)
Amoxicillin, co-amoxiclav
Cephalosporins
Carbapenems
Gentamicin
Trimethoprim
Nitrofurantoin
Ciprofloxacin
Vancomycin
Penicillins (few)
Flucloxacillin (poorly only)
Macrolides
Erythro & Clarithromycin
Tetracyclines
Doxycycline
Clindamycin

34. Coventry and Warwickshire Treatment Guidelines (Hospital)

35. UTI Usually Gram-negatives as a cause Pseudomonas E.coli
Other coliforms (proteus, klebsiella)
Less commonly enterococci, staphylococci
Pseudomonas
Mainly in catheterised patients or those with underlying urinary tract disorders

36. Case 4 Stephen, 17 years old Admitted through A&E No allergies
Lethargic, drowsy, unwell
High fever
Photophobia & stiff neck
No allergies

40. Coventry and Warwickshire Treatment Guidelines (Hospital)

41. Meningitis Need IV therapy
Neisseria menigitidis (meningococcus)
Strep. pneumoniae (pneumococcus)
Haemophilus influenzae (HiB)
Listeria (extremes of age, immunocompromise)
Need IV therapy
Need antibiotics with good meningeal penetration

42. Case 5
Albert, 82 years old
Had total hip replacement 5 days ago
On review today, unwell, coughing mucky sputum
Poor Oxygen sats, febrile
WCC 18, CRP 280
CXR – widespread opacity
No allergies, no previous microbiology samples

46. Coventry and Warwickshire Treatment Guidelines (Hospital)

47. Case 6 Ivy, 82 year old #neck of femur
Had a DHS 3 days ago.
Now has some erythema around the wound
Tender and wound feels hot. Well otherwise
Determined to be non-severe wound infection
Recent MRSA screen negative
Penicillin allergic (previous rash)

50. Coventry and Warwickshire Treatment Guidelines (Hospital)

51. Case 7 Rose, 75 year old Has been on medical ward for 2 weeks
Diabetic, hypertensive
Catheterised to measure urine output
Today, unwell, high temperature, hypotensive, MEWS score = 7.
No obvious cause – chest OK, abdo normal.
No known allergies

54. Coventry and Warwickshire Treatment Guidelines (Hospital)

55. Blood cultures are returned positive: MRSA grown after 24 hours
Flucloxacillin Resistant
Erythromycin Resistant
Gentamicin Sensitive
Vancomycin Sensitive
Rifampicin Sensitive
On careful examination, a cannula site is found to be very inflamed and other sources are excluded clinically.
Should the antibiotics be changed?

57. Sepsis Wide variety of causes
May be clear cause e.g. urosepsis or unclear
Needs to be treated promptly
broad spectrum antibiotics
IV route
‘empirical’
‘Targeted’ therapy if a cause is found subsequently

58. Summary Overview / revision of microbiology Route: Oral vs IV
Spectrum: Narrow vs broad
Therapy Empirical vs targeted
Antibiotics Single vs multiple
Which antibiotics and when
Allergies
Resistant organisms e.g. MRSA, ESBL
Guidelines will help in most cases!