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FLASHCARDS from MEDED lectures COPY > Infectious diseases > Flashcards

Infectious diseases Flashcards

1
Q

SBA 6

42 year old man

Previous pnemocystic pneumonia and oral ulcers

Presents with purple purpural lesion on nose

Which is the causative organism for this skin lesion?

A

E HHV8

Kaposi sarcoma

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2
Q

Herpes Simplex Virus

Definition

Types

Epidemiology - How common?

Aetiology and two phases

Presentation- symptoms and signs of HSV1

Presentation - symptoms and signs of HSV2

Investigations

Management

A

Herpes Simplex Virus

Definition

  • Infection of HSV 1 and 2. Infection can be dormant and re inflammation is triggered by physical/emotional stress or immunosuppression.

Epidemiology - How common?

Very common

90% adults seropositive for HSV1 by 30 years

Aetiology

- Primary infection occurs

  • Virus becomes dormant in trigeminal and sacral root ganglia
  • Reactivates if stress/immunosupression

Two phases

Latent phase: Dormant chronic infection, no infectious virions present= asymptomatic

Lytic phase: Active infections- viral replication and transport to skin

Presentation- symptoms and signs

of HSV1

  • Gingivostomatitis, cold sores [herpes labialis]
  • Herpetic whitlow [blister on finger]
  • Herpes simplex meningitis/encephalitis
  • Eczema herpeticum [emergency]
  • Keratoconjunctivitis
  • Systemic infection

HSV2

  • Genital herpes- chronic/life long
  • Flu-like prodrome
  • Vesicles/papules around genitals/anus
  • Urethral discharge
  • Shallow ulcers
  • Dysuria
  • Fever and malaise

Investigations

  • Clinical diagnosis
  • Viral culture/PCR

Management

  • Acyclovir [Topical, oral, IV]
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3
Q

SBA 1

Which organism is the most common cause for herpes labialis?

A

HSV-1

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4
Q

A 32 year old librarian presents to GP with a history of sharp tingling around his lips followed by a painful ulcer on the side of his mouth. O/E he has cervical lymphadenopathy and a blister on his finger. What is the pathogen?

A.Varicella Zoster Virus

B.Epstein-Barr Virus

C.Herpes Simplex Virus 1

D.Herpes Simplex Virus 2

Cytomegalovirus

A

C.Herpes Simplex Virus 1

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5
Q

SBA 4

50 year old man

Shingles rash

Which of following is not true?

A.This condition is Shingles

B.May occur due to stress

C.The rash may present bilaterally

D.Tingling in a dermatomal

distribution

E. The rash is painful

A

C The rash may present bilaterally

Shingles v unlikely to present bilaterally

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6
Q

How do heterophile antibodies form?

A

EBV can escape lymphatics, go to blood, infect B cells

Don’t contribute to symptoms

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7
Q

Methods of HIV transmission

A
    • placenta, birth, breastfeeding ^ doesn’t happen often anymore - - -
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8
Q

What are the four stages of an untreated HIV infection? Presentation - symptoms and signs of HIV

A
        • [below 200 CD4 T cells- illnesses] HIV only present due to complications/opportunistic infections due to low levels of CD4 T cells
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9
Q

Which disease characteristically causes ring enhancing lesions on CT head?

A

Toxoplasma gondi

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10
Q

What are the AIDS definining opportunitistic illnesses/pathogens?

A
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11
Q

What is seen on CXR in pneumocystic pneumonia?

A

Reticulonodular shadowing

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12
Q

SBA 7

47 y old HIV positive patient presents with:

Weakness of right leg

Headache

Fever

Confusion worsening over last few weeks

CT head shows multiple ring enhancing lesions

What organism is most likely to be causing this?

A.Plasmodium falciparum

B.Neisseria meningitidis

C.Toxoplasma gondii

D.Herpes Simplex Encephalitis

E.Pox virus

A

C Toxoplasma gondi

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13
Q

SBA 9

Most common causative agent for someone with a runny nose, sneezing and coughing?

A Rhinovirus

B Coronavirus

C Influenza

D Parainfluenza

E Respiratory syncytial virus

A

A Rhinovirus

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14
Q

SBA 10

37 y old

Lump posterior of neck= hot, erythematous and painful

Most likely causative agent?

A.Streptococcus pyogenes

B.Staphylococcus aureus

C.Mycobacterium Tuberculosis

D.Parasitic infection

E.Pseudomonas Aeruginosa

A

B Staphlococcus aurerus

[Strep pyogenes also can cause skin lumps but less likely]

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15
Q

What are tumours associated with HIV?

A
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16
Q

Investigations for HIV? First line Other tests

A

First lines - , - POC, less sensitive and specific - infants with HIV positive mothers, v sensitive, expensive - - Other tests - - - - -

17
Q

SBA 3

A 6-year old girl presents with a fever of 38.5, fatigue and a maculopapular rash on her face and trunk. Other children at school present with similar symptoms.

How should this patient be managed?

A.Hydration and NSAIDs.

B.Give oral acyclovir

C.Consider oral valaciclovir if within 24 h of rash onset

D.Paracetamol and Calamine lotion

E.Vaccinate with Varicella Immunoglobulin

A

A.Paracetamol and Calamine lotion

18
Q

How do you differentiate between viral and bacterial infection causing a sore throat?

A

Centor criteria??

19
Q

What is this rash?

A

Shingles

Varicella zoster

20
Q

Table of the eight human herpes viruses

A
21
Q

A wild medical student presents with sore throat and tonsillar exudates, posterior cervical lymphadenopathy and his basic observations are 38.9oC, HR is 90bpm and oxygen saturation on air is 99%. On examination there is splenomegaly.

His condition is most likely due to which of the following?

A.EBV

B.Streptococcus pyogenes

C.Adenovirus

D.Covid-19

E.Candida

A

A. EBV

22
Q

Varicella zoster

Definition

Epidemiology

Presentation

  • Chickenpox
  • Shingles

Investigations

Management:

  • Chickenpox
  • Shingles

Prevention

Complications

A

Varicella zoster

Definition

Infection of varicella zoster

Primary infection=chickenpox

Secondary reactivation in the dorsal root ganglion= shingles/zoster

Epidemiology

Chickenpox= 4-10 years

Shingles >50 years

90% of adults have antibodies

Presentation

  • Chickenpox
  • Prodromal malaise
  • Fever- mild
  • Maculopapular vesicular pruritic rash- face and trunk
  • Infectious for 48hrs before rash appears and until vesicles have crusted over- 7-10 days usually
  • Shingles
  • Tingling in a dermatomal distribution
  • Unilateral painful rash/skin lesions in dermatomal distribution
  • May occur due to stress
  • Recovery takes 10-14 days

Investigations

Clinical diagnosis

Consider viral serology and PCR, ELISA [but rare]

Management:

  • Chickenpox
  • Children
  • Paracetamol
  • Calamine lotion
  • Antihistamines
  • Adults
  • Acyclovir, valacyclovr, famacyclovir if within 24hr of rash onset
  • [There’s a person called val in the fam]
  • Shingles
  • First line: valacyclovr, famacyclovir
  • Second line: acyclovir
  • if within 72hr of rash onset
  • Give for 7 days

Prevention

Antibodies/vaccine available for:

Pregnant women

Immunocompromised

Complications

Chickenpox

Sepsis

Pneumonia

Encephalitis

Haemorrhagic complications

Shingles

Meningoencephalitis

Myelitis

Cranial nerve palsies

Vasculopathy

Gastrointestinal ulcers

Pancreatitis

Hepatitis

Sepsis

23
Q

Infectious mononucleosis

Definition

Aetiology

Presentation

Pathogenesis

Investigations

Management

Prognosis

EBV specific antibody

A

Infectious mononucleosis

Definition

Clinical condition resulting from primary infection with EBV virus

Also known as glandular fever

Aetiology

Transmission route: saliva/ resp droplets [eg. coughing, kissing]

Presentation

Fever

Lymphadenopathy- posterior cervical nodes

Pharyngitis + tonsilar exudate

HEPATOSPLENOMEGALY

Atypical lymphocytosis

Pathogenesis

EBV infects cells in throat- pharyngitis

Viral DNA incorporated into DNA of host cells

Virions enter lymphatic system

EBV enters B lymphocytes- some become latent and some have productive infection

Infected B lymphocytes produce random immunoglobulins eg heterophile antibodies

T cells destroy these lymphocytes

Latent infected B cells are not attacked by T cells- become immortal

Investigations

Temperature + basic obs

Full blood count - high WCC/lymphocytes- [highest in week two + three]

Blood film- Atypical lymphocytosis [large nuclei]

Heterophile antibodies- Monospot test [doesn’t affect symptoms/disease progression]

EBV specific antibodies

Real time PCR- EBV DNA detection

Management

Supportive symptomatic treatment- Paracetamol/ibuprofen

Corticosteroids if severe: obstructive pharyngitis, severe tonsil swelling, haemolytic anaemia

Contraindicated: amoxicillin/ampicillin= causes widespread maculopapular rash

Prognosis

95% recover with no complications in 3-21 days

EBV specific antibody

Early stages: EBV VCA [viral capsule antigen] IgM

Late stages + acute primary infection: EBV VCA IgG

Past infection: EBNA IgG [Epstein Barr nuclear antigen]

[Remember IgG = gone, IgM= iMMediate]

24
Q

A 13-year-old female patient presents to A&E with difficulty speaking.

4 days ago she experienced a sore, painful throat, which progressively got worse. She has difficulty swallowing.

On examination there is bilateral tonsillar exudate. There are 3 tender swellings on the anterior border of the sternocleidomastoid muscle.

Her observations are: T 39.1, HR 90, BP 113/68, SpO2 97%.

What is the most likely diagnosis?

A.Infectious mononucleosis

B.Viral tonsillitis

C.Common cold

D.Bacterial tonsillitis

E.Chickenpox

A

D.Bacterial tonsillitis

Anterior lymph nodes - not posterior lymph nodes= so infectious mononucleosis

25
Q

HIV

Infection

Transmission

Stages of infection

Presentation

Investigations

Other tests

A

HIV

Infection process

Retrovirus

Envelope glycoprotein [gp120] binds to CD4 and CCR5

Reverse transcriptase makes viral DNA

Incorporated into viral genome

Viral proteins/virions replicate

T Cell death

Transmission

Sexual contact

Blood/organ transfusion

IV drugs

Pregnancy/childbirth/breast feeding

Occupational

Stages of infection

Seroconversion

4-8 weeks after infection

Fever, night sweats, lymphadenopathy, sore throat, rash, oral ulcers, myalgia, headache, encephalitis, diarrhoea

Early/asymptomatic

18 months to 15 years

Persistent lymphadenopathy + minor symptoms

AIDS

Secondary diseases reflecting severe immunodeficiency

CD4 cell count <200/mm3

Presentation

Opportunistic infections due to immunocompromisation:

Bacterial: Mycobateria, staphylococcus, salmonella, encapsulated organisms

Viral: HHV8/Kaposi Sarcoma, VZV- recurrent shingles, HSV, CMV, HPV- warts, EBV- oral hairy leukoplakia, papovavirus- leukoencephalopathy

Fungal - Cryptococcus, invasive aspergillus, pneumocystis pneumonia, candida

Protozoa- toxoplasma,cryptosporidia, microsporidia

[Ring lesions in CT brain- toxoplasma gondii

Pneumonia- causes CXR infiltrates]

Investigations

ELISA- Western blot

Serum HIV rapid test

Serum HIV DNA PCR [infants]

CD4 count- monitor immune status + staging

Serum viral load [HIV RNA]- millions of copies

FBC, U+E, LFT

Other tests

Drug resistance

Serum hep B and C serology

Syphilis screening

TB - tuberculin skin test

26
Q

Hairy Leukoplakia

Definition

Aetiology

A

Hairy Leukoplakia

Definition

Irregular white painless plaques on lateral tongue- cannot be scraped off

Aetiology

Caused by EBV

Happens in HIV patients or people immunosuppressed because of organ transplants

27
Q

Candidiasis

Definition

Epidemiology

Aetiology

Conditions/Types

Risk factors [for each type]

Symptoms [for each type]

Investigations

Other investigations to exclude differentials or risk factors

A

Candidiasis

Definition

Infection with candida species

Thrush

Epidemiology

V common

Oral candiasis- 40-70% of adults and children

Aetiology

Dimorphic fungus infection

Candida albicans - commonly causes thrush

Conditions/types of candida infection

Oral candidiasis/oesophageal trush

Vulvovaginitis/balanitis

Diaper rash

Infective endocarditis

Disseminated candiasis [in blood stream, multiple organs affected]

Risk factors

Oral candidiasis/oesophageal thrush-> immunocompromised/steroid inhalers

Vulvovaginitis/balanitis-> diabetes, antibiotic use

Infective endocarditis-> IV drug use

Disseminated candiasis-> immunocompromise/neutropenia

Symptoms

Oral candidiasis/oesophageal thrush- dysphagia

Vulvovaginitis/balanitis- itching, soreness, redness, thick cottage cheese discharfe

Diaper rash

Infective endocarditis

Disseminated candiasis- fever, hypotension, leucocytosis

Investigations

Clinical diagnosis

Basic obsevations + examinations

Swabs useless- b/c commensal in a lot of people anyway

Other investigations to exclude differentials or risk factors

Urinalysis- UTI

Random/fasting blood glucose + glucose tolerance test- diabetes

HIV antibodies

Vaginal pH- STIs

Management

Antifungal [-azole]

Microconazole oral gel

Nystatin suspension

For vulvovaginal- intravaginal cream/pessary or oral antifungal

For oesophageal/systemic- amphotericin B

28
Q

HIV associated tumours

A

Kaposi’s sarcoma

  • may present as a pink or violaceous [purple] patch on the skin or in the mouth
  • AIDS defining condition
  • Caused by HHV8

Squamous cell carcinoma

[particularly cervical or anal due to HPV]

Lymphoma

29
Q

Tonsilitis

Definition

Epidemiology

Aetiology

- viral

- bacterial

Signs

Symptoms

Investigations

How to distinguish between viral and bacterial?

A

Tonsilitis

Definition

Acute inflammation of the parenchyma of the palatine tonsils

Epidemiology

V common

More common in children- five to fifteen y/o

Aetiology

- viral: rhinovirus, coronavirus, adenovirus [associated with infectious mononucleus infection too]

- bacterial: group A streptococcus, mycoplasma pneumoniae, neisseria gonorhhae

Symptoms and signs

Pain on swallowing

Tonsilar exudate

Tonsilar swelling/enlargment and erythema

Sudden onset sore throat

Fever >38C

Anterior cervical lymphadenopathy

Investigations

Clinical diagnosis- history, exam, basic obs

How to distinguish between viral and bacterial?

Centor criteria

Fever>38C

Tonsilar exudate

Anterior cervical lymphadenopathy/lymphadenitis- painful

No cough

30
Q

Common cold

Definition

Epidemiology

Aetiology

Investigations

Signs

Symptoms

Management

A

Common cold

Definition

Mild, self limiting, viral upper resp tract infection

Epidemiology

V common

Aetiology

Viral infection

In order of most to least common viruses:

Rhinovirus [50%]

Coronavirus

Influenza

Parainfluenza

Respiratory syncitial virus

Signs and Symptoms

Runny nose

Sneezing

Cough

Sore throat

Fever

Headache

Malaise

Investigations

Clinical diagnosis

FBC, throat swab, sputum culture, CRP, CXR- consider but rare

Management

Symptomatic supportive:

Analgesia

Antipyretic

Hydration

Decongestant [oxymetazozline nasal, ipratropium nasal]

Sometimes: anti tussive, antihistamine

31
Q

Abscess

Definition

Aetiology

Types

Table of presentations

Investigation

Management

Complications

A

Abscess

Definition

Collection of pus in a tissue, organ or cavity created by fibrosis

Aetiology

Usually bacteria

  • External [on skin]= Staph aureus

Rarely - parasites, foreign objects

Types

External- Skin

  • Cutaneous
  • Subcutaneous

Internal

  • Lung
  • Brain
  • Kidneys
  • Perianal [diabetes, IBD]
  • Tonsils
  • Teeth
  • Incisional

Signs and symptoms

- External

Erythema

Hot

Painful

Oedema/swelling

Loss of function

  • aka dolor, calor, rubor, tumor, functio laetia

- Internal

Systemic signs

Fever

Pain

Investigation

Clinical diagnosis- history, exam, obs

Ultrasound can help

Management

External/uncomplicated:

Aspiration

Incision and drainage

Severe/multiple infection sites/cellulitis/sepsis/rapid progression:

Antibiotics

Incision and drainage

Excision if severe

FLASHCARDS from MEDED lectures COPY (35 decks)

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