Infection and immunity Flashcards by Rhianna Jones

What type of bacteria is staph aureus? What infections is it associated with?

Gram positive cocci
Grape shaped

Septic arthritis
Hospital acquired pneumoniaf
Impetigo
Cellulitis

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What type of bacteria is coagulase negative staph?

What infections is it associated with?

Gram positive cocci
Eg staph saprophyticus and staph epidermis

UTI
Prosthetic devices via biofilms

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What type of bacteria is strep pneumoniae?

What infections is it associated with?

Group A strep
Gram positive cocci
Chains

Community acquired pneumonia
Meningitis
ENT infection

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What type of bacteria is strep pyogenes?

What infections is it associated with?

Group A strep
Gram positive cocci

Necrotising fasciitis
Strep throat

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What type of bacteria is strep viridans?

What infections is it associated with?

Gram positive cocci

Endocarditis

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What type of bacteria is clostridium difficile?

What infections is it associated with?

Gram positive bacilli

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What type of bacteria is TB?

Acid fast bacilli

Mycobacterium

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What type of bacteria is neisseria meningitidis?

What infections is it associated with?

Gram negative diplococci

Meningitis

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What type of bacteria is neisseria gonorrhoea?

What infections is it associated with?

Gram negative diplococci

STI
Septic arthritis

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What type of bacteria is haemophilus influenzae?

What infections is it associated with?

Gram negative cocci

Community acquired pneumonia
Bronchiectasis/COPD flare

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What type of bacteria is Escherichia Coli?

What infections is it associated with?

Gram negative bacilli

UTI
Traveller’s diarrhoea
Meningitis (neonates)

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What type of bacteria are pseudomonas aeruginosa and burkholderia cepacia?
What infections is it associated with?

Gram negative bacilli

CF pneumonia

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Which organisms are most commonly associated with bronchiolitis?

Respiratory syncytial virus

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Which organisms are most commonly associated with community acquired pneumonia?

Strep pneumoniae
Haemophilus influenzae
(Staph aureus)

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Which organisms are most commonly associated with hospital acquired pneumonia?

Staph aureus

Pseudomonas aeruginosa

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Which organisms are most commonly associated with pneumonia in alcoholics?

Klebsiella pneumoniae

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Which organisms are most commonly associated with CF flares?

Staph aureus
Haemophilus influenzae
Aspergillus fumigatus
Pseudomonas aeruginosa
Burkholderia cepacia

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Which organisms are most commonly associated with COPD or bronchiectasis flares?

Haemophilus influenzae

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Which organisms are most commonly associated with endocarditis?

Strep viridans
Staph aureus
Coagulase negative staph (on prosthetic valves)

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Which organisms are most commonly associated with meningitis at various ages?

Neonates - E coli and group B strep
Elderly - Listeria monocytogenes
Everyone else - Strep pneumoniae, Neisseria meningitidis, Haemophilus influenzae

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Which organisms are most commonly associated with septic arthritis?

Staph aureus
Strep A
Neisseria Gonorrhoea

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Which organisms are most commonly associated with necrotising fasciitis?

Strep pyogenes

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Which organisms are most commonly associated with dog bite?

Pasturella multocida

Clostridium tetani

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Which organisms are most commonly associated with UTI?

E Coli

Strep saprophyticus

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Which organisms are most commonly associated with acne?

Propioni acnes

Which organisms are most commonly associated with impetigo?

Staph aureus

Which organisms are asplenic patients most susceptible to?

Encapsulated eg neisseria meningitidis Spleen releases complement including opsonins. Therefore Decrease in ability to recognise microbes (particularly because no visible pamp without opsonin) and decrease in ability to recruit phagocytes.

Which infections do you not give first line amoxicillin/co-amoxiclav?

Endocarditis - vancomycin Meningitis - ceftriaxone C diff - metronidazole UTI - trimethoprim

What is the triple therapy for h pylori?

LAC - 14 days Lansoprazole Amoxicillin Clarithromycin

What is the standard treatment for TB?

RIPE Rifampicin Isoniazid Pyrazinamide Ethanbutol All 4 for 2 months RI for 4 further months

What are the side effects of the TB drugs?

Rifampicin - hepatitis, orange secretions, CYP inducer Isoniazid - peripheral neuropathy, give vit B6, CYP inhibitor Pyrazinamide - hepatitis, gout Ethanbutol - optic neuritis - acuity and colour blindness

What is the treatment for a CURB 1-2 pneumonia?

Amoxicillin or doxycycline

What is the treatment for a CURB 3+ pneumonia?

Co amoxiclav + clarithromycin or Doxycycline + clarithromycin

What is the treatment for septic arthritis?

Co amoxiclav or clindamycin

What is the treatment for centor 3 or 4 tonsillitis?

Penicillin V or erythromycin

What is the mechanism of action of penicillin?

Beta lactam that inhibits the transpeptidase that catalyzes the final step in cell wall biosynthesis, the cross-linking of peptidoglycan

What is the mechanism of action of vancomycin?

Glycopeptide | Inhibits cell wall synthesis

What is the mechanism of action of gentamicin?

Aminoglycoside | Inihibits protein synthesis

What is the mechanism of action of erythromicin?

Macrolide | Inhibits protein synthesis

What is the mechanism of action of ciprofloxacin?

Quinolone | Inhibits DNA synthesis

What is the mechanism of action of trimethoprim?

Folic acid antagonist

What is the difference between amoxicillin and co amoxiclav?

Clavulanic acid to inhibit beta lactamase in penicillin resistant bacteria

Which antibiotics are most associated with a risk of c diff?

Cephalosporins eg ceftriaxone Clindamycin Penicillins

What is a hypersensitivity reaction/

An antigen specific immune response that is inappropriate or excessive.

Describe the Gell and Coombs classification of hypersensitivity reactions

``` I - atopy and anaphylaxis II - transfusion reaction, Goodpastures III - SLE IV - Contact dermatitis, scabies, TB V - Grave's disease, myaesthenia gravis ```

Describe the pathophysiology of anaphylaxis

Phase 1 Silent 1st exposure, TH2 phenotype of CD4 T cell tells B cell to switch IGm to IGe This primes the mast cells Phase 2 Antigen crosslinking on the primed mast cells causes them to release histamine, leukotrienes and prostaglandins

What is the treatment for anaphylaxis?

``` 0.5mg IM adrenalin (can have several doses) 100mg IV hydrocortisone oxygen fluid monitor airway ```

Describe the pathogenesis of TB

Type 4 hypersensitivity reaction (T cell mediated) Mycobacteria detected and phagocytosed inside macrophage where they multiply and are taken to lymph nodes. In the lymph node this is the Ghon complex. Either then primary TB (mild) Or T cells send it latent Then can have secondary disease (severe)

What is miliary TB?

Secondary active disease that is disseminated across the body Usually in immunocompromised

What does a negative quantiferon test mean?

Never had TB

What does a positive quantiferon test mean?

Latent or active TB

What does a negative mantoux mean?

Never vaccinated or exposed to TB | Give BCG

What does a positive mantoux mean?

Either vaccinated already or exposed to TB in some way | Do not give BCG

Describe the histology of TB

Caseous necrosis and granulomas (epithelioid histiocytes) with Langhan's giant cells

Describe how TB appears in radiology?

Patchy consolidation with cavitating lesions | Hilar lymphadenopathy

Describe the HIV stages?

``` Acute phase 1 - asymptomatic 2 - CD4 <500 3 - CD4 <350 4 - CD4 <200 ```

At what stage should antiretrovirals be started for HIV?

At diagnosis

What conditions are commonly seen at CD4 counts <500, <200, <100?

<500 - Candidiasis, TB, Herpes zoster, leukoplakia, Kaposi's sarcoma <200 - Pneumocystis jirovecii pneumonia (PCP), toxoplasmosis <100 - Cytomegalovirus, meningitis, oesophageal candidiasis

Which type of pneumonia is associated with HIV?

Pneumocystis jirovecii pneumonia (PCP)

How would the results of hepatitis B serology look in a patient who is immune due to infection?

HBsAg (exposure) - positive antiHBs (immunity) - positive

How would the results of hepatitis B serology look in a patient who is immune due to vaccination?

HBsAg (exposure) - negative antiHBs (immunity) - positive over 100

How would the results of hepatitis B serology look in a patient who has active disease?

HBsAg (exposure) - positive antiHBs (immunity) - negative antiHBc - positive IgM

How would the results of hepatitis B serology look in a patient who has chronic disease?

HBsAg (exposure) - positive antiHBs (immunity) - negative antiHBc - positive IgG

Which antibiotics can you give in general instead of co-amoxiclav in penicllin allergic patients?

Cefuroxime (cephalosporin generally for lung but be careful in severe/proper allergy) Clindamycin (macrolide generally for MSK) Doxycycline (tetracycline generally low risk for c diff)