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Alex's MRCP Cards > Infectious Disease > Flashcards

Infectious Disease Flashcards

1
Q

Gram positive cocci?

A

StaPhylococci

StrePtococci

(including enterococci)

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2
Q

Gram negative cocci?

A

N for negative

  • Neisseria meningitidis
  • Neisseria Gonorrhoeae
  • Also Maroxella
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3
Q

Gram +ve rods? (Bacilli)

A

ABCDL

  • Actinomyces
  • Bacillus antracis (anthrax)
  • Clostridium
  • Diphtheria
  • Listeria monocytogenes
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4
Q

Gram -ve rods?

A

Everything that is not the other three

  • Pseudomonas
  • E.coli
  • Enterobacter
  • Klebsiella
  • Salmonella
  • Shigella, Proteus
  • Bordatella pertussis
  • Haemophilus
  • H Pylori
  • Legionella
  • Camplyobacter
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5
Q

Miscellaneous/Poorly staining species?

A

Intracellular Bacteria

  • Chlamydia
  • Rickettsia
  • Borella

Poorly Staining

  • Mycoplasma
  • Legionella
  • Helicobacter

Acid Fast Strain

  • Mycobacteria
  • Nocardia
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6
Q

Antibiotics with anti-anaerobic activity?

A
  • Penicillins
  • Cephalosporins (except ceftazidime)
  • Erythromycin
  • Metronidazole
  • Tetracycline
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7
Q

Antibiotics with no anti-anaerobic activity?

A
  • Gentamicin
  • Ciprofloxacin
  • Ceftazidime
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8
Q

Incubation periods?

A

Less than 1 week

  • Scarlet fever
  • Influenza
  • Diphtheria
  • Meningococcus

1 - 2 weeks

  • Malaria
  • Measles
  • Dengue fever
  • Typhoid

2 - 3 weeks

  • Mumps
  • Rubella
  • Chickenpox

Longer than 3 weeks

  • Infectious mononucleosis
  • Cytomegalovirus
  • Viral hepatitis
  • HIV
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9
Q

Live vaccines?

A
  • BCG
  • measles, mumps, rubella (MMR)
  • oral polio
  • oral typhoid
  • yellow fever
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10
Q

Other vaccines (non-live)?

A

Whole killed organism/inactivated

  • Rabies
  • Influenza

Detoxified Exotoxins

  • Tetanus

Fragment/Extracts of Organism/Virus

  • Diphtheria
  • Pertussis
  • Hepatitis B
  • Meningococcus, Pneumococcus, Haemophilus

Other

  • Cholera - inactivated strains of vibrio cholerae along with recominant B-subunit of cholera toxin
  • Hep B - contains HBsAg absorbed onto aluminium hydroxide adjuvant, prepared from yeast cells
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11
Q

Post-exposure prophylaxis?

A

Hep A

  • Human normal immunoglobulin (HNIG) or hep A vaccine

Hep B

  • If from HBsAg +ve source
    • If exposed peron is a known responder to HBV vaccine then –> booster dose.
    • If in process of being vaccinaed or non-responder –> hep B immune globulin (HBIG) and the vaccine
  • If from unknown source
    • Consider booster dose of HBV vaccine. If non-responder give HBIG + vaccine
    • If in process of being vaccinated then accelerate course of HBV vaccine

Hep C

  • Monthly PCR - if seroconversion then interferon +/- ribavirin

HIV

  • PEP - Tenofovir, Emtricitabine, Lopinavir and Ritonavir - ASAP, up to 72 hours after, continue for 4 weeks
  • Serological testing at 12 weeks

Varicella Zoster

  • VZIG for IgG negative pregnant women/immunosuppressed
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12
Q

Tetanus vaccine?

A
  • Given at: 2 months, 3 months, 4 months, 3-5 years, 13-18 years
  • High risk wounds –> give IM human tetanus immunoglobulin (irrespective of whether 5 doses of vaccine given)
  • High risk wounds = compound fractures, delayed surgical intervention, significant degree of devitalised tissue
  • If vaccination Hx unknown or incomplete - dose of tetanus vaccine along with IM human tetanus Ig for high risk wounds
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13
Q

Tetanus?

A

Cause

  • Tetanospasmin endotoxin released by clostridium tetani
  • Teatnus spores in soil –> introduced by a wound
  • Prevents release of GABA

Features

  • Prodrome fever, lethargy, headache
  • Trismus (lockjaw)
  • Risus sardonicus
  • Opisthotonus (arched back, hyperextended neck)
  • Spasms (e.g. Dysphagia)

Management

  • Supportive therapy including ventilatory support and muscle relaxants
  • Intramuscular human tetanus Ig for high-risk wounds
  • Metronidazole cover
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14
Q

Features of HIV seroconversion?

A
  • Sore throat
  • Lymphadenopathy
  • Malaise, myalgia, arthralgia
  • Diarrhoea
  • Maculopapular rash
  • Mouth ulcers
  • Rarely meningoencephalitis

Man returns from trip abroad with maculopapular rash and flu-like illness - think HIV seroconversion

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15
Q

Immunological changes in progressive HIV?

A
  • Reduction in CD4 count
    • Increase B2-Microglobulin (IBM)
    • Decrease IL-2 production (DIL=DELL) –> IBM & DELL
  • Polyclonal B-cell activation
  • Decreased NK cell function
  • Decreased delayed hypersensitivity responses
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16
Q

Vaccines that can be used in HIV if CD4 >200, and contraindicated?

A

If CD4 >200

  • MMR
  • Varicella
  • Yellow fever

Contraindicated

  • Cholera (CVD103-HgR)
  • Influenza-intranasal
  • Poliomyelitis-oral (OPV)
  • Tuberculosis (BCG)

Everything else can be used in all HIV infections

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17
Q

Diarrhoea in HIV?

A

Can be due to the virus itself (HIV enteritis) or opportunistic infections

  • Cryptosporidium + other protozoa (most
    common)
  • Cytomegalovirus
  • Mycobacterium avium intracellulare - CD4 <50, deranged LFTs
  • Giardia

Cryptosporidium - incubation 7 days. Acid fast stain (Ziehl-Neelsen) may reveal characteristic red cysts.

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18
Q

Factors which reduce vertical HIV transmission?

A
  • Maternal antiretroviral therapy - should be commenced between 28-32 weeks and continue intrapartum
  • Mode of delivery (caesarean section) - zidovudine infusion commenced 4 hours prior to start of section
  • Neonatal antiretroviral therapy - zidovudine orally for 4-6 weeks
  • Infant feeding (bottle feeding)
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19
Q

Kaposi’s sarcoma?

A
  • Caused by HHV-8 (Human Herpes Virus 8)
  • Presents as purple papules or plaques on the skin or mucosa (e.g. Gastrointestinal and respiratory tract)
  • Skin lesions may later ulcerate
  • Respiratory involvement may cause massive hemoptysis and pleural effusion
  • Radiotherapy + resection
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20
Q

PCP pneumonia?

A
  • Pneumocystis jiroveci is an unicellular eukaryote, generally classified as a fungus but some authorities consider it a protozoa
  • PCP is the most common opportunistic infection in AIDS
  • All patients with a CD4 count < 200/mm³ should receive PCP prophylaxis

Features

  • Dyspnoea, dry cough, fever
  • Very few chest signs
  • Extrapulmonary (rare) - hepatosplenomegaly, lymphadenopathy, choroid lesions

Ix

  • CXR - bilateral interstitial pulmonary infiltrates, may be normal
  • Exercise-induced desaturation
  • Sputum often fails to show PCP - BAL often needed for silver stain

Mx

  • Septrin
  • IV pentamidine in severe cases
  • Steroids if hypoxic
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21
Q

Biliary disease and pancreatitis in HIV?

A

Biliary Disease

  • Sclerosing cholangitis due to CMV, cryptosporidium and microsporidia

Pancreatitis

  • Secondary to anti-retroviral tx (didanosine)
  • Opportunistic infections (CMV)
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22
Q

Meningitis CSF summary?

A
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23
Q

Summary of streptococci?

A

Alpha Haemolytic Streptococci

  • Strep pneumoniae - pneumonia, meningitis, otitis media
  • Strep viridans - endocarditis

Beta Haemolytic Streptococci

  • Group A
    • Strep pyogenes - impetigo, cellulitis, nec fascitis, pharyngitis/tonsillitis
    • Immunological reactions can cause rheumatic fever or post-strep glomerulonephritis
    • Erythrogenic toxins cause scarlet fever
    • Penicillin is abx of choice
  • Group B
    • Strep agalactiae - nenonatal meningitis and septicaemia
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24
Q

Staphylococcal toxic shock syndrome?

A
  • Fever: temperature > 38.9ºc
  • Hypotension: systolic blood pressure < 90 mmHg
  • Diffuse erythematous rash
  • Desquamation of rash, especially of the palms and soles
  • Involvement of three or more organ systems: e.g. Gastrointestinal (diarrhoea and vomiting), mucous membrane erythema, renal failure, hepatitis, thrombocytopenia, CNS involvement (e.g. Confusion)

Severe systemic reaction to staphylococcal exotoxins

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25
Q

Necrotising Fasciitis?

A

Type 1 = caused by mixed anaesrobes and aerobes (often occurs post-surgery in diabetics)

Type 2 = caused by Strep pyogenes

Features

  • Acute onset
  • Painful, erythematous lesion develops (cellulitis like)
  • Extremely tender over infected tissue

Mx

  • Urgent surgical debridement
  • IV abx
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26
Q

Listeria monocytogenes?

A

Gram +ve bacillus

Spreads via contaminated food - unpasteurised dairy products

Can induce miscarriage

Features

  • Diarrhoea, flu-like illness
  • Pneumonia, meningoencephalitis
  • Ataxia and seizures
  • CSF may show pleocytosis, with ‘tumbling motility’ on wet mounts

Sensitive to amoxicillin/ampicillin

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27
Q

Anthrax?

A
  • Bacillus anthracis, a Gram positive rod
  • Spread by infected carcasses

Features

  • Painless black eschar (cutaneous ‘malignant pustule’, but no pus)
  • May cause marked oedema
  • Can cause GI bleeding

Treat with ciprofloxacin

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28
Q

Legionella?

A

Legionella Pneumophilia

Colonises water tanks - no person to person transmission

Features

  • Flu-like symptoms
  • Dry cough
  • Lymphopenia
  • Hyponatremia
  • Deranged LFTs

Diagnosed with urinary antigen

Treat with macrolides (erythromycin)

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29
Q

Leptospirosis (Weil’s disease)?

A

Questions refer to sewage works, farmers, vets or people who work in an abattoir

Leptospira interrogans (Spirochaete)

Spread classically by contact with infected rat urine

Features

  • Fever
  • Flu-like symptoms –> WITHOUT PRODUCTIVE COUGH
  • Renal failure (seen in 50% of patients)
  • Jaundice
  • Subconjunctival hemorrhage
  • Headache, may herald the onset of meningitis

Mx

  • LP to confirm meningeal involvement
  • High dose ben pen or doxy
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30
Q

Cause of epiglottitis?

A

Haemophilus influenzae type B

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31
Q

Lyme disease?

A

Borreliosis

Caused by 3x species of bacteria belonging to genus Borrelia

  • Borrelia burgdorefer - main cause in USA
  • Borrelia afzelii and Borrelia garinii - main cause in Europe

Features

  • Erythema chronicum migrans (small papule at site of tick bite –> develops into larger annular lesion with central clearing - bulls eye)
  • Systemic symptoms - malaise, fever, arthralgia

Later features

  • CVS - heart block, myocarditis
  • Neurological - cranial nerve palsies, meningitis
  • Polyarthritis
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32
Q

Mantoux test?

A
  • Immune mediated type IV hypersensitivity reaction
  • Ml of 1:1,000 purified protein derivative (PPD) injected intradermally
  • Result read 2-3 days later
  • Erythema & induration > 10mm = positive result - this implies previous exposure including BCG
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33
Q

Heaf test?

A

Classically involves injection of PPD equivalent to 100,000 units per ml to the skin over the flexor surface of the left forearm. It is then read 3-10 days later

  • Negative - no induration, 6 minute puncture scars
  • Grade 1 - 4-6 puncture sites indurated
  • Grade 2 - Confluent puncture sites form indurated ring
  • Grade 3 - Extensive induration to form disc (5-10mm)
  • Grade 4 - Severe induration >10mm with or without blistering

Grades 1-2 = previous BCG or avian tuberculosis

Grades 3-4 require CXR and follow up

34
Q

Causes of false negatives for Mantoux/Heaf test?

A
  • Miliary TB
  • Sarcoidosis
  • HIV
  • Lymphoma
  • Very young age (e.g. < 6 months)
35
Q

Treatment for active tuberculosis?

A

Initial Phase (2 months)

  • Rifampicin
  • Isoniazide
  • Pyrazinamide
  • Ethambutol

Continuation Phase (4 months)

  • Rifampicin
  • Isoniazid
36
Q

Mangement of latent TB/meningeal TB?

A

Latent

  • Isoniazid alone for 6 months

Meningeal

  • Prolonged period of treatment (12 months) with addition of steroids
37
Q

Side effects of TB treatment?

A

Rifampicin

  • Liver enzyme inducer
  • Hepatitis
  • Orange secretions
  • Flu like symptoms

Isoniazid

  • Peripheral neuropathy - prevent with vitamin B6
  • Optic neuritis (less common than ethambutol)
  • Hepatitis, agranulocytosis
  • Liver enzyme inhibitor

Pyrazinamide

  • Hyperuricaemia causing gout
  • Hepatitis

Ethambutol

  • Optic neuritis (visual acuity check before and during)
  • Dose adjustment in renal impairment

Streptomycin (resistant TB)

  • Vestibular damage –> vertigo and vomiting
  • Cochlear damage –> deafness
  • Anigioedema
  • Nephrotoxicosis
38
Q

Leprosy (Hansen’s Disease)?

A

Cause

  • Mycobacterium leprae
  • Mycobacterium lepromatosis

Features

  • Nodular skin lesions
  • Erythematous raised plaque like lesions in arms and legs

Can be progressive, causing permanent damange to skin, nerves, limbs and eyes

Mx

  • Skin biopsy and needle test
  • <5 lesions –> rifampicin and dapsone for 6 months
  • >5 lesions –> rifampicin, clofazimine and dapsone 12 months
39
Q

Features of severe malaria? Complications?

A

Severe Malaria

  • Schizonts on a blood film
  • Parasitemia > 2%
  • Hypoglycemia
  • Temperature > 39 °c
  • Severe anemia
  • Complications as below

Complications

  • Cerebral malaria: seizures, coma
  • ARF: blackwater fever, secondary to intravascular hemolysis, mechanism unknown
  • Acute respiratory distress syndrome (ARDS)
  • Hypoglycemia
  • Disseminated intravascular coagulation (DIC)
40
Q

Management of uncomplicated falciparum malaria?

A

Strains resistant to chloroquine are prevalent in certain areas of Asia and Africa

WHO 2010 guidelines: artemisinin-based combination therapies (ACTs) as first-line therapy

Examples

  • artemether plus lumefantrine
  • artesunate plus amodiaquine
  • artesunate plus mefloquine
  • artesunate plus sulfadoxine-pyrimethamine
  • dihydroartemisinin plus piperaquine
41
Q

Management of severe falciparum malaria?

A
  • A parasite counts >2% will usually need parenteral treatment irrespective of clinical state
  • IV artesunate is now recommended by WHO in preference to intravenous quinine (2010 guidelines)
  • If parasite count > 10% then exchange transfusion should be considered
  • Shock may indicate coexistent bacterial septicemia - malaria rarely causes hemodynamic collapse
42
Q

Most common causes of non-falciparum malaria?

A
  1. Plasmodium vivax - most common, Central America and Indian subcontinent
  2. Plasmodium ovale - Africa
  3. Plasmodium malariae

Almost always chloroquine sensitive

In vivax and ovale - use Primaquine to destory liver hypnozoites

43
Q

Leishmaniasis?

A

Caused by protozoa Leishmania, spread by sand flies.

Multiplies in monocyctes and macrophages

Incubation period can extend to 10 years

44
Q

3 types of Leishmaniasis?

A
  1. Cutaneous Leishmaniasis
    • Caused by Leishmania tropica or Leishmania mexicana
    • Crusted lesion at site of bite
    • May be underlying ulcer
  2. Mucocutaneous Leishmaniasis
    • Caused by Leishmania brasiliensis
    • Skin lesions may spread to involve mucosae of nose, pharynx
  3. Visceral Leishmaniasis
    • Mostly caused by Leishmania donovani
    • Occurs in Mediterranean, Asia, South America, Africa
    • Fever (typically twice in 24hours), sweats, rigors
    • Massive splenomegaly, hepatomegaly
    • Pancytopenia secondary to hypersplenism
    • Poor appetite*, weight loss
    • Grey skin - ‘kala-azar’ means black sickness or black fever
45
Q

Trypanosomiasis?

A
  • Protozoal disease
  • Two main forms
    • American Trypanosomiasis (Chagas’ disease)
    • African Trypanosomiasis (Sleeping sickness)
      • Trypanosoma gambinese - West Africa
      • Trypanosoma rhodesiense - East Africa
        • Both spread by the tsetse fly
46
Q

Trypanosoma rhodesiense?

A

Acute clinical course

  • Trypanosoma chancre - tender subcutaneous nodule at site of infection
  • Enlargement of posterior cervical lymph nodes
  • Later: central nervous system involvement e.g. Meningoencephalitis

Management

  • Early disease: IV pentamidine or suramin
  • Later disease or central nervous system involvement: IV melarsoprol
47
Q

Chagas’ disease?

A

Caused by Trypanosoma cruzi

  • 95% asymptomatic in aucte phase
  • Chagoma (erythematous nodule at site of infection) and periorbital oedema sometimes seen
  • Chronic chagas’ –> affects heart and GI tract

Complications

  • Myocarditis –> HF and arrhythmias
  • GI –> megaoesophagus and megacolon –> dysphagia and constipation

Management

  • Treatment is most effective in the acute phase using azole or nitroderivatives such as benznidazole or nifurtimox
  • Chronic disease management involves treating the complications e.g. heart failure
48
Q

Schistosomiasis?

A

Parasitic flatworm infection

  • Schistosoma mansoni and Schistosoma intercalatum: intestinal schistosomiasis
  • Schistosoma Hematobium: urinary schistosomiasis
    • Typically presents as a ‘swimmer’s itch’ in patients who have recently returned from Africa.
    • Frequency, haematuria and bladder calcification
    • Schistosoma Hematobium is a risk factor for squamous cell bladder cancer
    • Mx = single dose of oral praziquantel
49
Q

Rabies?

A

Features

  • Prodrome: headache, fever, agitation
  • Hydrophobia: water-provoking muscle spasms
  • Hypersalivation

Following animal bite in at risk countries

  • If an individual is already immunised then 2 further doses of vaccine should be given
  • If not previously immunised then human rabies immunoglobulin (HRIG) should be given along
    with a full course of vaccination
50
Q

Animal bite choice of abx if pen allergic?

A

Doxy and metronidazole

51
Q

Cat scratch disease?

A

Caused by gram -ve rod Bartonella henselae

  • fever
  • history of a cat scratch
  • regional lymphadenopathy
  • headache, malaise
52
Q

Chickenpox general stuff?

A
  • Infectivity = 4 days before rash, until 5 days after the rash first appeared
  • Incubation period = 11-21 days
  • School exclusion - 5 days from start of skin eruption
    • Immunocompromised/newborns with peripartum exposure –> varicella zoster immunoglobulin (VZIG)
    • If chickenpox develops then IV aciclovir
53
Q

Complications of chickenpox?

A

Secondary bacterial infection of the lesions

  • Pneumonia: varicella pneumonia is the most common and serious complication of chickenpox infection in adults. Auscultation of the chest is often unremarkable –> IV acyclovir
  • Encephalitis (cerebellar involvement may be seen)
  • Disseminated hemorrhagic chickenpox
  • Arthritis, nephritis and pancreatitis may very rarely be seen
54
Q

Foetal varicella syndrome?

A

Risk of VFS following exposure if 1% if before 20 weeks

Very small chance 20-28 weeks, no chance after 28 weeks

Features

  • Skin scarring, eye defects (microphthalmia), limb hypoplasia,
    microcephaly and learning disabilities

Management of Exposure

  • If there is any doubt about the mother previously having chickenpox maternal blood should be
    checked for varicella antibodies
  • If the pregnant woman is not immune to varicella she should be given varicella zoster immunoglobulin (VZIG) as soon as possible. RCOG and Greenbook guidelines suggest VZIG
    is effective up to 10 days post exposure
  • Consensus guidelines suggest oral aciclovir should be given if pregnant women with chickenpox present within 24 hours of onset of the rash
55
Q

Measles?

A
  • RNA paramyxovirus
  • Spread by droplets
  • Infective from prodrome until 5 days after rash starts
  • Incubation period = 10-14 days

Complications

  • Encephalitis: typically occurs 1-2 weeks after the onset of the illness.
  • Subacute sclerosing panencephalitis: very rare, may present 5-10 years following the illness
  • Febrile convulsions
  • Pneumonia, tracheitis
  • Keratoconjunctivitis, corneal ulceration
  • Diarrhoea
  • Increased incidence of appendicitis
  • Myocarditis
56
Q

Gonorrhoea complications?

A

Local

  • urethral strictures
  • epididymitis and salpingitis (hence may lead to infertility)

Disseminated Gonococcal Infection

  • Haematogenous spread from mucosal infection
  • Triad = tenosynovitis, migratory polyarthritis and dermatitis.
  • Later complications = septic arthritis, endocarditis and
    perihepatitis (Fitz-Hugh-Curtis syndrome)
57
Q

Genital warts?

A

HPV 6 and 11 (16, 18 and 33 predispose to cervical cancer)

Management

  • Podophyllum or cryotherapy
    • Multiple, non-keratinised warts are generally best treated with topical agents whereas solitary, keratinised warts respond better to cryotherapy
  • Imiquimod = topical cream, 2nd line
  • Often resistant to treatment, recurrence common - most infections clear within 1-2 years
58
Q

Genital herpes?

A

HSV 2 (cold sores are HSV 1)

  • Primary attacks often severe, associated with fever; subsequent attacks generally less severe and localised to one site
  • Features –> severe gingivostomatitis, cold sores, painful genital ulceration
  • Management
    • Gingivostomatitis: oral aciclovir, chlorhexidine mouthwash
    • Cold sores: topical aciclovir although the evidence base for this is modest
      Genital herpes: oral aciclovir. Some patients with frequent exacerbations may benefit from longer term aciclovir
59
Q

Syphilis?

A

Spirochaete - Treponema pallidum

Primary

  • Chancre - painless ulcer at site of sexual contact
  • Often not seen in women

Secondary (4-10 weeks after initial infection)

  • Systemic symptoms: fevers, lymphadenopathy
  • Rash on trunk, palms and soles
  • Buccal ‘snail track’ ulcers (30%)
  • Condylomata lata

Latent period

Tertiary

  • Gummas
  • Aortic aneurysms
  • General paralysis of the insane
  • Tabes dorsalis (slow degeneration of the sensory neurons. The degenerating nerves are in the dorsal column; proprioception, vibration, and fine touch).
60
Q

Diagnosis of syphilis?

A

Serological tests divided into

  1. Cardiolipin tests
    • Syphilis infection leads to the production of non-specific antibodies that react to cardiolipin
    • Examples include VDRL (venereal disease research laboratory) & RPR (rapid plasma reagin)
    • Insensitive in late syphilis
    • Becomes negative after treatment
    • Causes of false positives = pregnancy, SLE, antiphospholipid, TB, leprosy, malaria, HIV
  2. Treponemal specific antibody tests
    • Example: TPHA (Treponema pallidum hemagglutination test)
    • Remains positive after treatment
61
Q

Lymphogranuloma venereum?

A

Chlamydia trachomatis

Three stages

  1. Small painless pustule which later forms an ulcer
  2. Painful inguinal lymphadenopathy
  3. Proctocolitis
62
Q

Cause of BV? Criteria for diagnosis? Pregnancy?

A

Overgrowth of anaerobes such as Gardnerella vaginalis

Fall in lactic acid producing aerobic lacobacilli resulting in raised vaginal pH

3 of the 4 following for diagnosis

  • Thin, white homogenous discharge
  • Clue cells on microscopy
  • Vaginal pH > 4.5
  • Positive whiff test (addition of potassium hydroxide results
    in fishy odour)

Managmenet = 5-7 days oral metronidazole

Pregnancy - increased risk of preterm labour, LBW, late miscarriage - oral metronidazole can be used throughout pregnancy

63
Q

Potential complications of chlamydia?

A
  • Epididymitis
  • Pelvic inflammatory disease
  • Endometritis
  • Increased incidence of ectopic pregnancies
  • Infertility
  • Reactive arthritis
  • Perihepatitis (Fitz-Hugh-Curtis syndrome)
64
Q

Chlamydia psittaci?

A
  • Parrot disease, parrot fever
  • Characterized by malaise, fever, myalgias and pneumonia
  • Exposure to an ill bird and a rash (Horder’s spots) are pathognomonic.
  • Erythromycin or tetracyclines are the drugs of choice.
65
Q

Congenital infections?

A

Most common = CMV

66
Q

Toxoplasma Gondii?

A
  • Protozoa which infects the body via the GI tract, lung or broken skin
  • Its oocysts release trophozoites which migrate widely around the body including to the eye, brain and muscle.
  • The usual animal reservoir is the cat, although other animals such as rats carry the disease.
  • Most infections asymptomatic - if symptomatic normally self-limiting infection, features resembling infectious mono –> less commonly meningoencephalitis and myocarditis
67
Q

Gastroenteritis organisms?

A
68
Q

Cholera?

A

Vibro cholerae (gram -ve)

Features

  • Profuse ‘rice water’ diarrhoea
  • Dehydration
  • Hypoglycemia

Management

  • Oral rehydration therapy
  • Antibiotics: doxycycline, ciprofloxacin
69
Q

Giardiasis?

A

Causes by flagellate protozoan Giardia lamblia

Faecal oral route

Features

  • Often asymptomatic
  • Lethargy, bloating, abdominal pain
  • Non-bloody diarrhoea
  • Chronic/prolonged diarrhoea, malabsorption and lactose intolerance can occur
  • Stool microscopy for trophozoite and cysts are classically negative, therefore duodenal fluid aspirates or ‘string tests’ (fluid absorbed onto swallowed string) are sometimes needed
70
Q

Salmonella?

A

Aerobic gram -ve rods (not normally present in gut)

Features

  • Initially systemic upset as above
  • Relative bradycardia
  • Abdominal pain, distension
  • Constipation: although Salmonella is a recognised cause of diarrhoea, constipation is more common in typhoid
  • Rose spots: present on the trunk in 40% of patients, and are more common in paratyphoid

Possible Complications

  • Osteomyelitis (especially in sickle cell disease where Salmonella is one of the most common pathogens)
  • GI bleed/perforation
  • Meningitis
  • Cholecystitis
  • Chronic carriage (1%, more likely if adult females)
71
Q

Shigella?

A
  • Causes bloody diarrhoea, abdo pain
  • Severity depends on type: S sonnei (e.g. from UK) may be mild, S flexneri or S dysenteriae from abroad may cause severe disease
  • Treat with ciprofloxacin
72
Q

African tick typhus?

A

Caused by Rickettsiae

  • Black sopits on thigh
  • Hx of tick bites
  • Low grade fever
  • Faint macular rash
73
Q

Rocky mountain spotted fever?

A

Spread by ticks, common in the USA

  • Fever
  • Rash on hands, feet which later –> desequamte (peel)
  • Tachycardia with no hypotension (unlike Staphylococcal Toxic Shock Syndrome)

Treat with doxycycline

74
Q

Mediterranean spotted fever?

A

Caused by the Rickettsia conorii and transmitted by the dog tick Rhipicephalus sanguineus

  • Incubation period: 7 days.
  • Abrupt onset - chills, high fevers, myalgia and joints pain, severe headache, photophobia and diarrhea.
  • The location of the bite forms a black spots or ulcerous crust (tache noire).
  • Around the fourth day of the illness exanthem appears, first macular and then maculopapular and sometimes petechial

Treat with Doxycycline

75
Q

Dengue fever?

A

Type of viral haemorrhagic fever (yellow fever, Lassa fever, Ebola)

Low platelet count and raised transaminase level is typical

  • Transmitted by the Aedes aegyti mosquito
  • Incubation period of 7 days
  • Africa, Central and South America, the Caribbean, the Eastern Mediterranean, South and Southeast Asia, and Oceania.
  • Form of DIC called dengue haemorrhagic fever (DHF) may develop –> Dengue shock syndrome (DSS)

Features

  • Causes headache (often retro-orbital)
  • Myalgia
  • Pleuritic pain
  • Facial flushing (dengue)
  • Maculopapular rash
  • Pyrexia

Treatment is symptomatic - fluid resus, transfusions etc.

76
Q

Infectious mononucleosis?

A

Caused by EBV

  • Sore throat
  • Lymphadenopathy
  • Pyrexia
  • Malaise, anorexia, headache
  • Palatal petechiae
  • Splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
  • Hepatitis
  • Presence of 50% lymphocytes with at least 10% atypical lymphocytes
  • Hemolytic anaemia

Management - rest, fluids, simple anaglesia. No contact sport for 8 weeks.

77
Q

Malignancies associated with EBV infection?

A
  • Burkitt’s lymphoma
  • Hodgkin’s lymphoma
  • Nasopharyngeal carcinoma
  • HIV-associated central nervous system lymphomas

Hairy leukoplakia also associated with it (non-malignant)

78
Q

Hepatitis E?

A
  • RNA virus
  • Spread by the faecal-oral route, incubation period = 3-8 weeks
  • Common in Central and South-East Asia, North and West Africa, and in Mexico
  • Causes a similar disease to hepatitis A, but carries a significant mortality (about 20%) during pregnancy
  • Does not cause chronic disease
79
Q

Parvovirus B19?

A

Erythema infectiosum (also known as fifth disease or ‘slapped-cheek syndrome’)

  • Systemic symptoms: lethargy, fever, headache
  • ‘slapped-cheek’ rash spreading to proximal arms and extensor surfaces

Other presentations

  • Asymptomatic
  • Pancytopenia in immunosuppressed patients
  • Aplastic crises e.g. in sickle-cell disease (parvovirus B19 suppresses erythropoiesis for about a week so aplastic anemia is rare unless there is a chronic hemolytic anemia)
80
Q

Orf?

A
  • Condition found in sheep and goats although it can be transmitted to humans.
  • Caused by the parapox virus.

In humans

  • Generally affects the hands and arms
  • Initially small, raised, red-blue papules
  • Later may increase in size to 2-3 cm and become flat-topped and hemorrhagic

In animals

  • Scabby leisons around mouth and nose
81
Q

Nematodes?

A
  1. Ancylostoma braziliense
    • Most common cause of cutaneous larva migrans
    • Common in Central and Southern America
  2. Strongyloides stercoralis
    • Acquired percutaneously (e.g. Walking barefoot)
    • Causes pruritus and larva currens - this has a similar appearance to cutaneous larva migrans but moves through the skin at a far greater rate
    • Abdo pain, diarrhoea, pneumonitis
    • May cause gram negative septicemia due to carrying of bacteria into bloodstream
    • Eosinophilia sometimes seen
    • Management: thiabendazole, albendazole. Ivermectin also used, particularly in chronic infections
  3. Toxocara canis
    • Commonly acquired by ingesting eggs from soil contaminated by dog faeces
    • Commonest cause of visceral larva migrans
    • Other features: eye granulomas, liver/lung involvement
82
Q

Tape worms?

A

Cysticercosis

  • Caused by Taenia solium (from pork) and Taenia saginata (from beef)
  • Management: niclosamide

Hyatid disease

  • Caused by the dog tapeworm Echinococcus
    granulosus
  • Life-cycle involves dogs ingesting hydatid cysts from sheep liver
  • Often seen in farmers
  • May cause liver cysts
  • Management: albendazole

Alex's MRCP Cards (13 decks)

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