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Revision Qs > Infectious Disease 2 > Flashcards

Infectious Disease 2 Flashcards

1
Q

What is the most common causative organism of malaria? What are the other 3? New one?

A 
Plasmodium falciparum most common
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Plasmodium knowlesi is the new one
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2
Q

Typical incubation period of falciparum malaria? What about vivax/ovale?

A

1-2 weeks

Up to a month for falciparum, 6 months for vivax/ovale

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3
Q

Which two organisms might be implicated in a malaria ‘relapse’ ages after initial presentation?

A

Vivax and ovale

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4
Q

Malaria parasite associated with long incubation period and nephrotic syndrome?

A

Plasmodium malariae

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5
Q

When are the carriers of malaria parasites most active?

A

Dusk-dawn

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6
Q

Typical fever pattern for falciparum malaria?

A

Quotidian - daily

Can be irregular, tertian (every 3rd day) or subtertian (36 hour cycles)

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7
Q

Common symptoms of malaria?

A 
Fever - swinging, recurrent
Chills and rigors
Cough
Headache 
Nausea, vomiting, diarrhoea
Myalgia
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8
Q

Signs of malaria?

A

Hepatosplenomgealy
Jaundice
Abdominal tenderness

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9
Q

What sorts of things indicate severe malaria infection?

A

Respiratory distress
Reducing consciousness, fits
Bleeding or shock
Renal failure, nephrotic syndrome

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10
Q

Major differentials for fever in returning traveller?

A

Malaria
Dengue
Typhoid
Viral hepatitis

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11
Q

Diagnostic investigations for malaria?

A

Blood films - thick (presence) and thin (type)
Dipstick tests
Nucleic acid based testing

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12
Q

ABCD of malaria prophylaxis?

A

Awareness of risk - destination, travel advice, high risk categories
Bite avoidance - mosquito nets, keeping inside/covered dusk-dawn
Chemoprophylaxis - chloroquine, mefloquine, malarone, doxycycline
Diagnosis - and prompt treatment

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13
Q

What Chemoprophylaxis is used for low-risk malaria areas? Common side effects?

A

Chloroquine

GI upset

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14
Q

What chemoprophylaxis is used for high risk malaria areas e.g. Subsaharan Africa? Side effects?

A

Mefloquine

Psychosis, convulsions, coma

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15
Q

What should be suspected in a systemically unwell woman with no obvious source of infection but offensive vaginal discharge?

A

?retained tampon - staphylococcal toxic shock syndrome

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16
Q

How is typhoid spread?

A

Fecal-oral incl food (shellfish), water

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17
Q

RFs for typhoid fever?

A 
Foreign travel to risk areas - Asia, Africa, S America
H2RBs, PPIs, antacids, GI pathology
Recent Abx
Immunosuppression, extremes of age
Haemaglobinopathies (SCD)
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18
Q

How long is the incubation period for typhoid?

A

Similar to malaria - 1-3 weeks, nearly always within 1 month

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19
Q

Over how long does untreated typhoid manifest?

A

4 weeks, where 3 is the worst and 4 is start of recovery

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20
Q

Classical key Sx of typhoid?

A

Gradually worsening persistent fever, evening exacerbation
Malaise, headaches
Epistaxis
GI - abdo pain (RIF), distension, hepatosplenomegaly
Rash (rose spots on abdomen, chest)

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21
Q

Investigations for typhoid?

A

Blood cultures, marrow cultures

Serology for H and O antigens (Widals test)

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22
Q

Is there a vaccine for typhoid?

A

Yes

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23
Q

What is the spectrum of illness with Dengue fever?

A

Dengue fever -> dengue haemorrhagic fever -> dengue shock syndrome

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24
Q

Virus and vector for dengue fever?

A

Flavivirus spread by Aedes mosquito

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25
Q

Incubation period of dengue?

A

2-7 days, typically around 3

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26
Q

Key Sx of dengue?

A 
Abrupt onset high fever
Myalgias (breakbone)
Frontal/orbital headache
Generalised macular rash
GI upset
Haemolytic tendencies incl epistaxis
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27
Q

Features of dengue haemorrhagic fever?

A

Mucosal bleeding
Capillary permeability abnormalities - low protein, oedema, pleural effusions etc.
Hepatosplenomegaly

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28
Q

Diagnosis of dengue? What else should be done?

A

Serum IgM, IgG
Serum PCR
Should also do malaria films

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29
Q

Organism and spread of Lyme disease?

A

Deer tick bites spreading borrelia burgdorferi

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30
Q

Early symptoms of Lyme disease?

A

Erythema migrans - target lesion >5cm occurring at site of tick attachment, usually within 1m of bite
Plus or minus non-specific illness

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31
Q

Symptoms of disseminated Lyme disease?

A

Flu like illness
Facial nerve palsies, meningoencephalitis
Myocarditis
Lymphocytomas on earlobe/nipples (blue-red swellings)

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32
Q

Late manifestations of Lyme disease?

A

Arthralgias - typically recurrent, of large joints like knee
Acrodermatitis chronica atrophicans (blue red discolouration of extensor surfaces) alongside swelling and peripheral neuropathies
Neuro stuff

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33
Q

4 differentials for erythema migrans?

A

Bug bite reaction
Hives/urticaria
Ringworm
Cellulitis

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34
Q

Pathophysiology of infective endocarditis?

A

Background of Nonbacterial thrombotic endocarditis (platelet-fibrin vegetation) which gets infected

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35
Q

RFs for IE?

A

IVDU
Replacement heart valves, catheters, prostheses, haemodialysis
Structural heart abnormalities e.g. VSD, PDA
Recent dental work
Pre-existing valvular disease e.g. Hx of rheumatic fever
Autoimmune background
Hx of IE

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36
Q

Why do bacterial vegetations not get destroyed in IE/ why is there no substantial neutrophilia?

A

Valves are poorly vascularised - only platelets do first line attacking
Microemboli trigger RES (humoral arm) in spleen so AgAb complexes start getting formed, causing Sx

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37
Q

3 most common pathogens behind IE?

A

Strep viridans (a haemolytic)
Staph aureus
Coagulase negative staph

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38
Q

What pathogen is most implicated in IVDU or healthcare associated IE?(acute presentation)

A

Staph aureus

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39
Q

What bacteria is most implicated in native valve endocarditis/late prosthetic endocarditis? (Subacute)

A

Strep viridans (a haemolytic)

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40
Q

What bacteria have the biggest role in new prosthetic valve endocarditis?

A

Coagulase negative staph

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41
Q

Rarer bacterial causes of IE?

A

Enterococci and gram negatives
Pseudomonas
Fungi

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42
Q

Symptoms of acute/fulminant IE?

A

Fever, rigors
Acute heart failure
Arrhythmias
Septic shock

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43
Q

Common Sx of subacute IE?

A

Fever, night sweats (PUO)
Weight loss
TATT
Arthralgias

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44
Q

What does spiking PUO and conduction abnormalities with a heart murmur suggest?

A

Aortic root abscess secondary to IE

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45
Q

4 areas of signs of IE?

A

Systemic
Embolic
Cardiac
Immune vasculitis

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46
Q

Systemic signs of IE?

A 
Petechial haemorrhages in conjunctiva, palate, buccal
Roth spots
Oslers nodes, janeway lesions
Clubbing
Splinter haemorrhages
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47
Q

Cardiac signs of IE?

A

New or changing murmur
Conduction abnormalities
Heart failure

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48
Q

Embolic signs of IE?

A

Stroke, PE, peripheral infarcts, MI, DVT etc.

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49
Q

Immune vasculitis consequences of IE?

A

Immune complex nephritis -> haematuria, microalbuminuria
Splenomegaly
Petechial rash
Arthralgias

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50
Q

What does neutrophilia in the context of IE suggest?

A

Abscess formation

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51
Q

What is diagnostic of IE?

A

At least 3 sets of blood cultures, taken during temp spikes

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52
Q

Imaging for IE?

A

Echo - Transoesophageal if poss

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53
Q

What are the general principles behind IE treatment?

A

High dose, long term (4-6 week) Abx treatment based on culture sensitivities particularly if subacute
Combo synergistic therapy
E.g. Vanc and gent (covers S aureus) or Amox and gent for viridans

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54
Q

When might surgical involvement be required for IE?

A

Abscess formation
If in prosthetic valves (biofilm covered)
Large or persistent vegetations

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55
Q

SIGHT management of suspected C Diff?

A 
Suspected case of infectious diarrhoea, Abx history, no better cause
Isolate and investigate
Gloves and aprons (PPE)
Hand washing with soap and water
Test stools
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56
Q

What is C Diff?

A

Gram negative bacillus in many people which typically only causes trouble when normal gut flora wiped out e.g. By Abx treatment.
Can cause a pseudomembranous colitis (acute, exudative) via toxins A and B

57
Q

How is c diff transmitted and how does it remain in the environment?

A

Transmitted fecal-orally, can form spores in the environment and stay there for ages

58
Q

Drugs associated with c diff? (1 non-Abx)

A 
PPIs
Clindamycin
Macrolides
Vancomycin
B lactams
Cephalosporins
59
Q

Generally what sorts of antibiotics are associated with c diff infection?

A

IV, broad spectrum Abx

60
Q

Symptoms of c diff colitis?

A

Diarrhoea starting 5-10 days after commencing Abx (varying severity)
Fever, rigors, malaise
Colicky abdo pain

61
Q

Outline testing process for c diff?

A

Do stool testing - Glutamate dehydrogenase (GDH) positive = presence of C diff but not necessarily infection, toxins A/B positive = causing infection

62
Q

What should you do if a patient is positive for GDH but negative for toxins and still has diarrhoea?

A

Isolate anyway and retest for c diff

63
Q

2 patients, 1 with C diff 1 with MRSA. Which do you isolate first and why?

A

C diff, because it can form environmental spores which can be really hard to get rid of

64
Q

Besides SIGHT, management of c diff?

A

Stop offending Abx, consider changing to vanc or metronidazole
Conservative - fluids etc.

65
Q

Major complications of C diff infection?

A

Recurrence
Fulminant colitis, toxic megacolon, peroration
Splenic abscess
Dehydration, shock, AKI etc.

66
Q

Common Sx of HA-MRSA?

A

Can appear as boil/pustule, abscess particularly around wound sites
Fever, rigors, generally unwell

67
Q

Potential Sx of CA-MRSA infection?

A

Can cause severe cellulitis

68
Q

What type of bacteria is mycobacterium tuberculosis?

A

Acid fast bacillus

69
Q

What is the primary TB infection?

A

Spread by droplets, M TB gets engulfed in the lungs by macrophages and transported to hilar LNs -> granulomas around the body

70
Q

What may happen at the point of a primary TB infection?

A

May become symptomatic initially -> overt/active TB, miliary
May eliminate all the bacteria
May lay dormant in granulomas -> secondary infection of LTBI

71
Q

RFs for TB?

A

Being born in endemic area, big cities etc.
Social deprivation factors - homeless, alcohol, IVDU
HIV and other Immunocompromise
Elderly and children

72
Q

Constitutional and pulmonary symptoms of reactivated LTBI?

A

Fever, weight loss, night sweats TATT, anaemia
Cough, productive +/- bloodstained
Lobar collapse, bronchiectasis, pleural effusion etc.

73
Q

Second most common TB presentation (extra-pulmonary)?

A

Sterile pyuria - kidney lesions, abscesses, salpingitis, infertility, epididymitis

74
Q

MSK presentations of TB?

A

Potts vertebrae (collapse)
Arthritides
Osteomyelitis

75
Q

CNS presentations of TB?

A

Meningitis

Tuberculomas

76
Q

What CXR picture does primary TB infection give?

A

Central apical portion, left lower lobe infiltrate

+/- pleural effusion

77
Q

What CXR picture does reactivated TB show?

A 
Apical lesions (granulomas) - cavitating lesions
No pleural effusions
78
Q

What CXR does miliary TB show?

A

All over the shop (millet seed)

79
Q

How is TB investigated microbiologically?

A

Early morning sputum samples - bronchoscopy, lavage and gastric washing if necessary
Cultures take 4-8 weeks for confirmation and a further 3-4 for sensitivities (apart from Rifampicin)

80
Q

What histological investigation should be done for extra-pulmonary TB?

A

Biopsy of LNs and CXR

81
Q

Screening tests for TB?

A 
Tuberculin: Heaf test, Mantoux test (may be positive if had BCG)
IgG testing (IGRA)
82
Q

Basic management of TB infection?

A

Inform CDC
6 month 4 drug regime, dependant on sensitivities but generally Rifampicin isoniazid ethambutol pyrazinamide for 2m then Rifampicin and isoniazid for another 4

83
Q

Alternatives to first line TB drugs?

A

Streptomycin

Other macrolides, quinolones

84
Q

What must be monitored during TB drug therapy?

A 
LFTs as most can derange, renal impairment
Visual impairment (ethambutol)
Peripheral neuropathy (isoniazid)
Arthralgias (pyrazinamide)
85
Q

In whom is disseminated MAC disease most common?

A

HIV with low cd4 count - AIDS

86
Q

What does MAC infection cause in kids?

A

Cervical lymphadenitis - blue-purple discharging LN

87
Q

What is lady Windermere syndrome?

A

Pneumonitis in elderly women traditionally who have suppressed their cough reflex, caused by MAC infection

88
Q

What is hot tub lung?

A

MAC infection causing granulomatous pneumonitis related to inhaling aerosolised MAC in water, e.g. Poorly maintained hot tubs

89
Q

What is an important factor, but not pre-requisite in MAC infection?

A

Immunocompromise e.g. HIV, elderly, CF

90
Q

What is a Ghon complex?

A

Initial granuloma + infected lymph node in TB - may be on skin, in lungs

91
Q

What is leprosy/hansens disease?

A

Infection with mycobacterium leprae causing nothing initially, then years later skin lesions (discolouration) alongside neuropathy, eye changes and respiratory Sx

92
Q

Transmission of leprosy?

A

Droplet, normally close contact with infected

Animal (armadillo)

93
Q

What is impetigo?

A

Honeycomb golden crusting due to epidermal infection often caused by s aureus

94
Q

What is a furuncle?

A

Infection of whole hair follicle down to root causing micronecrosis
Caused by s aureus

95
Q

What is folliculitis?

A

Pustule formation around hair follicle caused by s aureus

96
Q

What is a carbuncle?

A

Infection of multiple hair follicles causing draining abscess formation

97
Q

What is flucloxacillin effective against?

A

S pyogenes
S pneunoniae
MSSA

98
Q

What is ludwigs angina?

A

Nec fasc of submandibular space

99
Q

What is Fournier’s gangrene?

A

Nec fasc of scrotum/vulva

100
Q

Signs indicative of nec fasc rather than cellulitis?

A

Pain disproportionate to visible signs and systemic illness
Bullae or ecchymosis
Tender beyond poorly demarcated borders

101
Q

What is osteomyelitis?

A

Infection of the bone marrow, which can spread to cortex and periosteum
Typically caused by s aureus incl MRSA

102
Q

What is a sequestrum?

A

Area of dead bone detached from healthy bone seen in osteomyelitis, acting as focus for chronic infection

103
Q

What is an involcrum?

A

Periosteum separated from underlying bone in osteomyelitis, acting as source for new bone growth

104
Q

What is the likely origin of osteomyelitis in kids or those with in dwelling catheters?

A

Haematogenous spread

105
Q

Rx for osteomyelitis?

A

Flucloxacillin and Rifampicin for 4-6 weeks

But wait for culture results!

106
Q

Gold standard diagnosis for osteomyelitis?

A

Bone cultures

107
Q

What enzyme distinguishes s aureus from other staph species?

A

Coagulate

108
Q

What is STSS?

A

Streptococcal toxic shock syndrome - shock caused by s pyogenes toxin exotoxin release

109
Q

What is TSS?

A

Toxic shock syndrome typically caused by staph aureus

110
Q

What differentiates STSS from TSS?

A

TSS often arise as shock with fever in otherwise healthy individual, has characteristic sunburn rash which causes desquamation in couple of weeks
STSS however comes from site of pre-existing skin infection, looks a bit like nec fasc but doesn’t include the sunburn rash

111
Q

What is SSSS?

A

Staphylococcal Scalded Skin Syndrome; widespread fluid filled blisters, possibly widespread desquamation
Ritter’s Disease of the newborn

112
Q

3 structural pathogenicity factors of s aureus?

A

Protein A
Peptidoglycan
Clumping factor

113
Q

What exotoxin in s aureus (MRSA) is associated with high virulence, necrotising pneumonia and potentially neutropenia?

A

Panton-Valentine Leukocidin

114
Q

What criteria is used to define haemolytic streptococci?

A

Lancefield criteria

115
Q

What is GAS?

A

B haemolytic streptococci - strep pyogenes

116
Q

What do B haemolytic streptococci do to blood?

A

Completely haemolyse it

117
Q

What is acute rheumatic fever?

A

A complication of GAS infection; autoimmune attack on endocardium/synovial tissue (migrating polyarthropathy)

118
Q

What disease does GAS in new mothers?

A

Puerperal sepsis

119
Q

What causes puerperal fever?

A

GAS

120
Q

What are 2 examples of alpha haemolytic streptococci? What do they do to blood?

A

Strep pneumoniae and strep viridans

Weakly oxidising so turn it green

121
Q

What is the classic GBS?

A

Strep agalactiae

122
Q

Important disease caused by GBS?

A

Neonatal meningitis and pneumonia, also elderly meningitis

123
Q

What can GBS bacteruria cause in a pregnant woman?

A

Stillbirth, prematurity, miscarriage

124
Q

Are enterococci gram positive or negative? 2 most common species?

A

Positive

Enterococcus faecalis and faecium

125
Q

Alternative name for enterococci?

A

Lactobacilli

126
Q

Are enterococci aerobic or anaerobic?

A

Facultative anaerobes

127
Q

What do enterococci intrinsically resist?

A

Cephalosporins

128
Q

3 examples of coliform bacteria?

A

Enterobacter
Klebsiella
Faecal coliforms e.g. E. coli

129
Q

3 examples of aminoglycosides?

A

Gentamicin
Streptomycin
Rifampicin

130
Q

3 examples of macrolides?

A

Clarithromycin
Erythromycin
Azithromycin

131
Q

How do macrolides work?

A

Protein synthesis inhibitors

132
Q

What type of bacteria are macrolides effective against?

A

Gram negatives e.g. Gonorrhoea

133
Q

What are the general side effects of aminoglycosides?

A

Ototoxicity

Nephrotoxicity

134
Q

How do vancomycin and teicoplanin work?

A

Inhibit cell wall synthesis via peptidoglycan formation

135
Q

General trend working through the generations of cephalosporins?

A

Better action vs gram negatives

136
Q

What are tetracyclines commonly used for?

A

Second line vs pneumonia (if penicillin allergy)

137
Q

What is metronidazole effective against?

A

Gram negatives, fungi and protozoa

138
Q

What is ciprofloxacin? Special relevance?

A

Fluoroquinolone

Good vs pseudomonas and used prophylactically vs bacterial meningitis

Revision Qs (28 decks)

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