3. Pathogenicity Factors
1. Adherence factors
Allow adherence to body surfaces
2. Invasins
Promote tissue invasion
3. Endotoxins/exotoxins
Cause the damage!
4. Factors that confer ability to evade immune
response
= virulence factors
= how bacteria cause disease
4. Which cause disease?
1. Classics
E.g. Mycobacterium tuberculosis
2. Commensals
E.g. Escherichia coli
3. Opportunists
E.g. Pneumocystis jiroveci
28. Macrolides
• Bacteriostatic
• Macrolide ring activity
– Binds irreversibly to 50S subunit of bacterial
ribosome; inhibits protein synthesis
• Used against Streptococci/MSSA in penicillin
allergy
• E.g. erythromycin
29. Aminoglycosides
• Bactericidal
• Bind irreversibly to 30S subunit of bacterial
ribosome
– Prevents elongation of polypeptide chain (tRNA)
• Good for Gram –ve aerobes
• E.g. gentamicin
34. Antibiotics used…
• Infection by organ system
• Reference: BNF
• Highlighted in red = those we probably need
to have a grasp of
35. GI
• Campylobacter enteritis
– Ciprofloxacin or erythromycin
• Salmonella
– Ciprofloxacin or cefotaxime
• Shigellosis
– Ciprofloxacin. Amoxicillin or trimethoprim can be used if
organism sensitive.
• Typhoid fever
– Ciprofloxacin or cefotaxime
• Clostridium difficile infection
– Oral metronidazole or oral vancomycin
• Biliary-tract infection
– Ciprofloxacin or gentamicin or a cephalosporin
• Peritonitis
– A cephalosporin + metronidazole or gentamicin + metronidazole
or gentamicin + clindamycin or piperacillin with tazobactam
36. CVS
• Endocarditis initial ‘blind’ therapy
– Flucloxacillin (or benzylpenicillin if symptoms less severe) +
gentamicin
• Endocarditis caused by staphylococci
– Flucloxacillin
• Endocarditis caused by streptococci (e.g. viridans
streptococci)
– Benzylpenicillin + gentamicin
• Endocarditis caused by enterococci (e.g. Enterococcus
faecalis)
– Amoxicillin (or vancomycin if penicillin-allergic or penicillin-
resistant) + gentamicin
• Endocarditis caused by haemophilus, actinobacillus,
cardiobacterium, eikenella, and kingella species (‘HACEK’
organisms)
– Amoxicillin (or ceftriaxone if amoxicillin-resistant) + low-dose
gentamicin
37. RS
• Haemophilus influenzae epiglottitis
– Cefotaxime or chloramphenicol IV
• Acute exacerbations of chronic bronchitis
– Amoxicillin (or tetracycline or clarithromycin; approx. 20% H.
influenzae strains amoxicillin-resistant)
• Low or moderate-severity community-acquired pneumonia
– Amoxicillin (or doxycycline or clarithromycin)
• High-severity community-acquired pneumonia of unknown
aetiology
– Co-amoxiclav + clarithromycin
• Pneumonia possibly caused by atypical pathogens
– Clarithromycin.
• Hospital-acquired pneumonia
– Early-onset infection (less than 5 days after admission to hospital), co-
amoxiclav or cefuroxime
– Late-onset infection (more than 5 days after admission to hospital), an
antipseudomonal penicillin (e.g. piperacillin with tazobactam) or a
broad-spectrum cephalosporin (e.g. ceftazidime) or another
antipseudomonal beta-lactam or a quinolone (e.g. ciprofloxacin)
38. CNS
• Meningitis initial empirical therapy
– Benzylpenicillin or cefotaxime
• Meningitis caused by meningococci
– Benzylpenicillin or cefotaxime
• Meningitis caused by pneumococci
– Cefotaxime
• Meningitis caused by Haemophilus
influenzae
– Cefotaxime
• Meningitis caused by Listeria
39. Urinary
• Acute pyelonephritis
– A broad-spectrum cephalosporin or a quinolone
• Acute prostatitis
– Ciprofloxacin or ofloxacin or trimethoprim
• ‘Lower’ urinary-tract infection
– Trimethoprim or nitrofurantoin or amoxicillin or
oral cephalosporin (e.g. cefalexin)
40. Genital
• Syphilis
– Benzathine benzylpenicillin (unlicensed) or doxycycline or
erythromycin
• Uncomplicated gonorrhoea
– Ciprofloxacin. Pharyngeal infection requires ceftriaxone.
• Uncomplicated genital chlamydial infection, non-
gonococcal urethritis and non-specific genital
infection
– Azithromycin or doxycycline
• Pelvic inflammatory disease
– Doxycycline + metronidazole + i/m ceftriaxone or ofloxacin
+ metronidazole
• Bacterial vaginosis
– Oral or topical metronidazole or topical clindamycin
41. ENT
• Pericoronitis (infected wisdom tooth)
– Metronidazole or amoxicillin
• Acute necrotising ulcerative gingivitis
– Metronidazole or amoxicillin
• Periapical or periodontal abscess
– Amoxicillin or metronidazole
• Periodontitis
– Metronidazole or doxycycline
• Throat infections
– Phenoxymethylpenicillin (or clarithromycin if penicillin-allergic)
• Sinusitis
– Amoxicillin or doxycycline or clarithromycin
• Otitis externa
– Flucloxacillin or clarithromycin
• Otitis media
– Amoxicillin (or clarithromycin if penicillin-allergic)
44. M/S
• Osteomyelitis
– Flucloxacillin or clindamycin if penicillin-allergic (or
vancomycin if resistant Staph. epidermidis or
metihcillin-resistant Staph. aureus)
• Septic arthritis
– Flucloxacillin or clindamycin if penicillin-allergic (or
vancomycin if resistant Staph. epidermidis or
methicillin-resistant Staph. aureus); cefotaxime if
gonococcal arthritis or Gram-negative infection
55. EBV
• Epstein Barr Virus = Human Herpes Virus 4
(HHV4)
• Cold symptoms infectious mononucleosis
• Fatigue, fever, sore throat, lymphadenopathy
• Risk if rupturing spleen so no sports for 1/12!
• Acetaminophen/NSAIDs to help fever/pain
• Normally remains in WBCs for life
• Ca risk if prolonged infection
• ? vaccines
58. Human Papilloma Virus - HPV
• Low risk – genital warts (STI)/skin warts
• High risk: Ca cervix, vagina, vulva, anus, penis
• Respiratory papillomatosis
• Untreatable; usually clears spontaneously
– Can treat the warts
• Vaccines: Cervarix, Gardasil
59. Herpes Simplex Virus - HSV
• = Human Herpes Virus (1 &2)
• Types:
– Orofacial herpes (most common), i.e. herpes labialis (cold sores)
– Genital herpes
– Herpes whitlow (hands)
– Ocular herpes (eyes)
– Herpes encephalitis (brain)…+ others!
• Watery blisters in skin/mucus membranes
• Lies latent in nerve cell bodies; outbreaks
• No cure per se
– ? vaccines under development
– Antivirals e.g. aciclovir cream
– Analgesia
– Anaesthesia (e.g. topical lignocaine)
60. Varicella Zoster Virus - VZV
• = Human Herpes Virus 3
• Fluid-filled blisters surrounded by reddened skin
• General malaise, sore throat, headache, etc.
• Rx:
– Topical antivirals e.g. aciclovir
– Ig for at risk individuals (neonates, pregnant, etc)
– Vaccine in seronegative/at risk individuals
• Varilrix/Varivax
– Pain management post shingles
61. Respiratory Syncitial Virus - RSV
• Common cause of bronchiolitis/viral pneumonia
in kids (< 6/12 mostly);
• Older children/adults get a cold (limited to URT)
• Rx:
– Paracetamol/ibuprofen
– Ribavirin
• Inhibits range of DNA/RNA viruses
– Palivizumab
• Monoclonal Ab
• Prevents serious LRTI in kids at risk
62. Influenza
• Oseltamivir and
zanamivir as post-
exposure prophylaxis
– Inhibit neuraminidase
• Vaccines
– Seasonal
• High risk individuals
– Pandemic
• Pandemrix/Celvapan for
swine ‘flu
• See lecture notes
63. Norovirus
• Winter vomiting bug; RNA virus
• Most common cause of gastroenteritis in UK
– D&V, fever, etc.
• Faeco-oral route/contaminated food & water
• Rx:
– Stay at home
– Paracetamol for fever symptoms
– Rehydrate!