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EOY3 > Infection and Immunity > Flashcards

Infection and Immunity Flashcards

1
Q

definition of pneumonia

A

lung infection with NEW consolidation seen on X-ray

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2
Q

causes of pneumonia

A 
streptococcus pneumoniae (80% of cases)
haemophilus influenzae (common in COPD patients) 
klebsiella pneumoniae (seen in alcoholics) 
pneumocystis jiroveci (seen in HIV patients)
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3
Q

CURB-65

A

used to assess severity of a patient with pneumonia
Confusion (new) AMT <8/10
Urea >7mmol/l
Respiratory rate > 30/min
Blood pressure <90 systolic or <60 diastolic
65 or older

if patient scores 2 or higher then admit to hospital

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4
Q

what antibiotics based on CURB score?

A

CURB 1 - amoxicillin
CURB 2 - amoxicillin and doxycycline
CURB 3 = co-amoxiclav and doxycycline

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5
Q

mumps

A

RBA paramyxovirus
MMR vaccine has an efficacy of ~80%
spread by droplets (infective seven days before and 9 days after parotid swelling starts) incubation period is 14-21days
symptoms: fever, malaise, muscular pain, parotitis (becomes bilateral in 70% of cases)
Rx: rest, paracetamol. is a notifiable disease

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6
Q

Gell and Coombs classification for hypersensitivity reactions

A

Type I - ANAPHYLACTIC - IgE, anaphylaxis and atopy (eczema and asthma)
Type II - CELL BOUND - IgG/IgM - AI haemolytic anaemia, Goodpasture’, rheumatic fever, acute haemolytic transfusion reaction
Type III - IMMUNE COMPLEX - IgG/IgA - SLE, post-strep glomerulonephritis
Type IV - DELAYED T CELL MEDIATED - GvHD, allergic contact dermatitis, MS
Type V - ANTIBODIES - Grave’s disease, Myasthenia Gravis

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7
Q

post-op pyrexia causes

A

early (0-5 days): blood transfusion, cellulitis, UTI, physiological systemic inflammatory infection, pulmonary atelectasis, hyperthermia post GA
late (5+ days): VTE, pneumonia, wound infection, anastomotic leak

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8
Q

chance of contracting hepatitis and HIV from a needlestick injury

A

Hep B > Hep C > HIV

1:3 > 1:30 > 1:300

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9
Q

hepatitis screen

A

HBsAg (shows if actively infected) positive in acute and chronic infections

anti-HBsAg (shows immunity) positive in resolved infections or if vaccinated

IgG anti-HBsAg (shows own immune response, takes time to develop) positive in chronic or resolved infections

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10
Q

the immune system

A

INNATE: 1st and 2nd line of defence
1st line: physical (skin, mucous membranes, cilia), physiological (coughs, sneezing, vomiting), chemical (low pH, Ig__) and biological (normal flora)
2nd line: phagocytes and chemicals (complement, cytokines and chemokines)

ADAPTIVE: antigen presenting cells

  • dendritic cells (LN, mucous membranes and blood, presents to T and B cells)
  • langerhan cells (skin, presents to T cells)
  • macrophages (various tissues, presents to T cells)
  • B cells (lymphoid tissue - produce own IgM - presents to T cells)
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11
Q

features of human leukocyte antigen

A

HLA’s are:

  • co-dominantly expressed so offspring has more versions than parents
  • are polymorphic so aren’t specific
  • have a variable protein binding cleft so have a broad specificity
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12
Q

major histocompatibility complex classes

A

Class I - found on all nucleated cells, endogenous pathway (presents peptides from intracellular microbes) CD8 and CD4 cells

Class II - only found on APCs, exogenous pathway (presents extracellular microbes by phagocytosis) CD4 cells

problems with MHC include cross-reactivity when the antigen is similar to the endogenous cell = AI disease e.g. T1DM, strep (pyrogenes) throat leading to rheumatic fever and heart disease

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13
Q

CD4 vs CD8 cells

A 
CD4 cells (aka T helper cells) activate CD8 cells and plasma cells (which produce antibodies) and creates T memory cell
CD8 (cytotoxic T cells) punch holes in the microbe to destroy it
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14
Q

which immunoglobin contributes to neonatal immunity?

A

IgG

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15
Q

which immunoglobulin is passed to baby in breast milk?

A

IgA

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16
Q

which is the first immunoglobulin to be secreted in response to infection?

A

IgM

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17
Q

which immunoglobulin is responsible for mediating type 1 hypersensitivity reactions and mast cell degranulation?

A

IgE

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18
Q

severe combined immunodeficiency (SCID)

A

X-linked
infections are severe, persistence, in unusual sites, recurrent
defect prevents the formation of T cells. failure to thrive, increased fungal infections, pneumocystis pneumonia and EBV
cannot give live vaccines and blood products must be eradicated before giving
stem cell transplantation may be successful

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19
Q

DiGeorge syndrome

A

22p11.2 deletion, failure to develop 3rd and 4th pharyngeal pouches
common features include congenital heart defects (e.g. tetralogy of fallot), learning difficulties, hypocalcaemia, recurrent viral and fungal infections and cleft palate.

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20
Q

HIV

A

virus penetrated CD4 cells and releases it’s RNA which is converted to DNA by reverse transcriptase and inserted into the host cell DNA, the host cell DNA is translated and transcribed producing more HIV cells.
features: typically 3-12 weeks post-infection, with a glandular fever type illness
diagnosis: HIV PCR and p24 antigen test
ELISA test and confirmatory Western Blot Assay

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21
Q

HIV treatment

A

HAART = 2 x NRTI and 1 x NNRTI or PI
NRTI (nucleoside reverse transcriptase inhibitors, except tenofovir which is a nucleotide RTI) e.g. emtricitabine or abacavir. ADR: peripheral neuropathy
PI (protease inhibitors - inhibit viral protease required for viral assembly) e.g. ritonavir and indinavir. ADR: rashes, central obesity
NNRTI (non-competitive reverse transcriptase inhibitor) e.g. nevirapine (used in pregnancy to prevent transmission)

integrase inhibitors (prevent integration of transcribed viral DNA into host genome) e.g. raltegravir
CCR5 receptor antagonists (prevent HIV-1 from entering and infecting immune cells by blocking CCR5 cell surface receptors) e.g. maraviroc
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22
Q

Malaria

A

commonest and most dangerous is plasmodium falciparum (Rx: artemether)
plasmodium vivax is second most common (Rx for all non-falciform: chloroquine)

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23
Q

Hepatitis A

A

RNA picornavirus
incubation period 2-4 weeks
faecal-oral spread (associated with infected shellfish)
usually self limiting
is a vaccine available for those living in endemic areas, are immunocompromised or at a particular risk (MSM< IVDU, occupational hazard)

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24
Q

Hepatitis B

A

dsDNA hepadnaviral
incubation period is 6-20 weeks
transmitted via bodily fluids (but not through breast milk)
vaccine in the UK for children and at risk groups (IVDU, healthcare staff, prisioners) anti-HBs used to determine if vaccine dose is adequate
treatment: PEGylated interferon alpha (reduced viral replication) and tenofovir + entecavir (suppresses viral replication)

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25
Q

Hepatitis C

A

ssRNA enveloped virus (flavivirus)
incubation period 6-9 weeks
transmitted via bodily fluids (but not through breast milk)
55-85% will develop chronic Hep C
at risk groups are IVDU and pts who had a blood transfusion before 1991
Rx: protease inhibitors (daclatasvir/simeprevir and sofosbuvir) +/- ribavirin (teratogenic so must wait 6 months before conceiving)

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26
Q

Hepatitis D

A

ssRNA
requires hepatitis B surface antigen so is either a co-infection or a superinfection
is transmitted via exchange of bodily fluids
Rx: interferon

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27
Q

Hepatitis E

A

ssRNA
faecal-oral route of infection (associated with contaminated water)
incubation period id 3-8 weeks
usually self limiting but carries a 20% mortality rate if pregnant

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28
Q

Tetanus

A

caused by the tetanospasmin exotoxin released from clostridium tetani. spores are present in the soil and may be introduced via a wound. prevents GABA release.
features: prodrome fever, lethargy, headache, spasms, lockjaw, dysphagia
Rx: supportive (including ventilation), IM tetanus immunoglobin, metronidazole ABx
vaccine is given to UK children routinely, provides 5 doses which is considered adequate for long term cover, the vaccine contains cell-free purified toxin.

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29
Q

define sepsis

A

the life-threatening organ dysfunction caused by a dysregulated host response to an infection

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30
Q

sepsis six

A

(BUFALO)
blood culture
urine output
fluids - fluid challenge unless CI
antibiotics - broad spectrum (e.g. meropenem) initially
lactate
oxygen - high flow, aim for >94% unless COPD

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31
Q

neutropenic sepsis

A

a common complication of chemotherapy, typically occurs 7-14 days after
neutrophil count of <0.05^10*9 in a patient having cancer treatment and has a temperature >38 or other signs/symptoms consistent with sepsis
prophylaxis: fluoroquinolone
Rx: immediate ABx - tazocin, if still unwell after 48hrs try meropenem +/- vancomycin, if still unwell after 4-6 days look for a fungal infection

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32
Q

types of shock

A 
septic
hypovolaemia 
neurogenic 
cardiogenic 
anaphylactic
33
Q

management of anaphylaxis

A 
if an adult: 
IM adrenaline 500micrograms (0.5ml 1 in 1000) can be repeated every five minutes 
200mg (IM or slow IV) hydrocortisone 
10mg (IM or slow IV) chlorphenamine 
IVF and O2 if required

can measure serum tryptase to confirm anaphylaxis up to 12 hours post attack

34
Q

clostridium difficile

A

a gram positive bacillus that produces an exotoxin that causes intestinal damage leading to pseudomembranous colitis
develops when the normal gut flora is suppressed by broad-spectrum antibiotics (commonly cephalosporins)
features: watery stools, increased WCC, abdominal pain and cramping
diagnosis: stool sample
Rx: if suspecting then isolate patient, PO metronidazole 10-14days, if severe/not responding add PO vancomycin, if life-threatening then PO vancomycin and IV metronidazole

35
Q

rheumatic fever

A

post-strep pyrogenes (strep throat) infection
jones criteria for diagnosis
complications include rheumatic heart disease

36
Q

sinusitis

A

facial pain worse on bending forward, nasal discharge, a post nasal drip may cause a chronic cough
Rx: analgesia, intranasal decongestants, if severe phenoxymethylpenicillin, if systemically unwell co-amoxiclav. if recurrent/chronic intranasal corticosteroids and referral to ENT

37
Q

Lyme disease

A

caused by spirochaete borrelia burgelorferi and is spread by tics
early: erythema chronicum migrans
later: heart block, myocarditis, cranial nerve palsies, meningitis, polyarthritis
it takes 3-8 weeks before antibodies are detectable
Rx: doxycycline (if early disease, amoxicillin if pregnant) or ceftriaxone (if disseminated disease

38
Q

leprosy

A

myobacterium leprae, intracellular acid fast bacillus
get erythematous or hypopigmented lesions, peripheral nerve involvement, saddle nose, loss of extremities secondary to infection
Rx: dapsone and rifampicin

39
Q

causes of meningitis

A

0-3 months: group B strep, E. coli, listeria monocytogenes
3 months-6 years: Neisseria meningitis, strep pneumoniae, haemophilus influenzae
6-60 years: Neisseria meningitis, strep pneumoniae
>60 years: strep pneumonia, Neisseria meningitis, listeria monocytogenes
immunocompromised: listeria monocytogenes

40
Q

symptoms of meningitis

A

photophobia
neck stiffness
non-blanching rash (doesn’t blanch as capillaries have been destroyed by septic shock)

41
Q

treatment of meningitis

A

cefotaxime or amoxicillin or benzylpenicillin

vaccine in the UK covers A, B and C

42
Q

symptoms of TB

A

weight loss, cough, haemoptysis, night sweats

43
Q

transmission of TB

A

mycobacterium tuberculosis (acid fast bacilli) is spready by aerosol droplets so commonly affects the lungs, although can affect anywhere in the body

44
Q

primary TB

A

a non-immune host is infected, a type 4 hypersensitivity reaction occurs forming a Ghon focus in the upper lobes of the lung (composed by tubercle-laden macrophages). ghon focus plus hilar lymphadenopathy = ghon complex.
in immunocompetent people the initial lesion usually heals by fibrosis = latent TB
in immunocompromised it may develop into disseminated TB = miliary TB

45
Q

secondary TB

A

if host with latent TB becomes immunocompromised the initial infection may reactivate
this can be due to steroids, HIV, malnourishment, other drugs

46
Q

extra-pulmonary TB

A 
CNS: tuberculosis meningitis 
vertebral bodies: Pott's disease
cervical lymph nodes: Scrofuloderma 
renal 
GI tract
47
Q

treatment of TB

A

Rifampicin 4/12
Isoniazid 4/12
Pyrazinamide 2/12
Ethambutol 2/12

48
Q

what gives false positives on the Mantoux test?

A

it’s used to screen for latent TB

false +ves if: miliary TB, sarcoidosis, HIV, lymphoma, or <6 months old

49
Q

management of an MRSA surgical site infection

A

incision and drainage debridement or amputation

ABx: mild/moderate: oral tetracyclines, oral co-trimoxazole. moderate/severe: vancomycin or teicoplanin

50
Q

which antibiotics affect cell wall synthesis?

A

beta-lactams: penicillins, cephalosporins, carbapenems

glycopeptides: vancomycin, teicoplanin
polymyxins: colistin

51
Q

which antibiotics affect nucleic acid synthesis?

A

affect folate synthesis: sulfamethoxazole, trimethoprim
affect DNA synthesis: fluoroquinolones, metronidazole
affect RNA polymerase: rifamycins

52
Q

which antibiotics affect protein synthesis?

A

affect 50S subunit: macrolides, clindamycin, chloramphenicol, fusidic acid and linezolid
affects 30S subunit: aminoglycosides, tetracyclines

53
Q

penicillin G

A

(benzylpenicillin, penicillin)
penicillin is used to treat syphilis
poor oral absorption so give IV
ADR: allergy, rash, N&V, C. diff, cholestasis

54
Q

penicillin V

A

(phenoxymethylpenicillin)

prophylaxis if splenectomy/hyposplenism, used in rheumatic fever

55
Q

amoxicillin

A

broad spectrum
used in CAP, sinusitis, otitis media and chronic bronchitis exacerbations
can get a rash with EPV

56
Q

co-amoxiclav

A

(amoxicillin and clavulanic)
broad spectrum
used in HAP and animal/human bite

57
Q

flucloxacillin

A

a penicillin
used for widespread impetigo, cellulitis and mastitis
ADR: allergy, rash, N&V, cholestasis

58
Q

cephalosporins

A

inhibit bacterial transpeptidase, later generations have increasing activity against gram negatives
3rd generation - broad spectrum: cefotaxime (used for acute pyelonephritis), ceftriaxone (used for acute pyelonephritis and gonorrhoea), ceftazidime (empirical treatment for neutropenic sepsis and used for acute pyelonephritis)

59
Q

carbapenems

A

e.g. meropenem
broad spectrum
inhibit bacterial transpeptidase, can be used for neutropenic sepsis
(imipenem is given with cilastatin to reduce renal metabolism)
ADR: N&V, C. diff, rash, eosinophilia, reduced platelets, increased LFTs, seizures

60
Q

licopeptides

A

-vancomycin and teicoplanin
inhibit cell wall synthesis, used for complicated gram positive (including MRSA), poor oral absorption (vancomycin is given orally in C. diff)
ADR: nephrotoxic, ototoxic, reduces platelets

61
Q

colislin

A

(polmyxins)
used against multi-resistant gram negatives, used in the inhaled form to treat ventilator-associated pneumonia
ADR: nephrotoxic in 50%

62
Q

gentamicin

A

(aminoglycoside)
acts on the amino-acyl site of the 30S subunit to cause misreading of mRNA - bactericidal
ADR: nephrotoxic, ototoxic and vestibular toxicity

63
Q

macrolides

A

erythromycin (treats chlamydia in children), azithromycin (single dose used to treat chlamydia) and clarithromycin (treats atypical pneumonia, exacerbations of chronic bronchitis and campylobacter)
ADR: (worse with erythromycin) GI upset, long QTc rhabdomyolysis with statins, cytochrome P450 inhibitor (less so with azithromycin) increases calcineurin inhibitor levels, increases warfarin levels

64
Q

doxycycline

A

(tetracycline)
used to treat chlamydia 7day course
CI in pregnancy, if <8 y/o (as affects teeth and bones)
ADR: N&V, photosensitivity and increased LFTs

65
Q

clindamycin

A
  • bacteriostatic, works on the 50S subunit - inhibits translocation
    ADR: increases risk of C. diff
66
Q

fusidic acid

A

first line in impetigo

67
Q

trimethoprim

A

folate antagonist - bacteriostatic
used for lower UTIs and acute prostatitis
inhibits creatinine secretion so increases creatinine without lowering the eGFR

68
Q

co-trimoxazole

A
  • folate synthesis inhibitor
    used for pneumocystis jirovecii
    good oral absorption and tissue/CSF penetration
    ADR: folate deficiency, haemolysis with G6PD deficiency
69
Q

fluoroquinolones

A

e.g. ciprofloxacin - broad spectrum
used against salmonella, shigellosis
ADR: CSN effects (reduced seizure threshold, peripheral neuropathy), increased QTc

70
Q

metronidazole

A

bactericidal - inhibits DNA synthesis
used for C. diff, gingivitis, bacterial vaginosis, anaerobic infections
good oral absorption
can get a disulfiram reaction with alcohol and it inhibits warfarin metabolism

71
Q

rifamycins

A

rifampicin and rifabutin
bactericidal, used against mycobacteria - TB, leprosy and legionnaire’s disease
ADR: hepatitis, myelosuppression and red secretions

72
Q

aciclovir

A
  • inhibits viral DNA polymerase, used for herpes and varicella zoster
73
Q

tamiflu

A
  • for influenza A and B
74
Q

azoles

A
  • inhibits cell membrane synthesis, fluconazole is used for candida
75
Q

polyenes

A
  • inhibits cell membrane function, used for systemic fungal infection
76
Q

antiprotozoal

A
  • metronidazole, used for amoeba and giardia
77
Q

define R0

A

the average number of cases that one case generates over the course of its infectious period in an otherwise non-immune, unaffected population

78
Q

Tazocin

A

used for neutropenic sepsis prophylaxis
broad spectrum
(piperacillin/tazobactam)

EOY3 (20 decks)

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