Infections Flashcards
1
Q
A
C - Herpes Simplex Virus 1
- an intensely painful infective ulcer on the fingertips is herpetic whitlow
- tingling sensation tends to precede herpes
- this is common in dentists as they are in contact with a lot of mouths
2
Q
A
D - paracetamol & Calamine lotion
- treatment for chickenpox in children is aimed at symptomatic relief
- in adults, treatment is aimed at eradicating the virus
- oral acyclovir is given in adults
- oral valaciclovir is the treatment for shingles
3
Q
A
B - this rash can only present unilaterally
- this is shingles, which has a dermatomal distribution
- it is caused by reactivation of VZV
- there is tingling in a dermatomal distribution
- treatment is with valaciclovir
- it is caused by a DNA virus
4
Q
A
EBV
- it is NOT streptococcus pyogenes as strep throat presents with anterior cervical lymphadenopathy
- EBV presents with posterior cervical lymphadenopathy
5
Q
A
E - Human herpesvirus 8
- this man has HIV, which predisposes him to Kaposi’s sarcoma
- this is caused by HHV8
6
Q
What is the name of HHV-1?
How is it transmitted and what is the clinical presentation?
A
herpes simplex virus - 1 (HSV-1)
Transmission route:
- respiratory droplets / saliva
Clinical presentation:
- gingivostomatitis (mouth or gum swelling)
- keratoconjunctivitis (inflammation of cornea & conjunctiva)
- herpes labialis (cold sores)
- temporal lobe encephalitis
7
Q
What is the name of HHV-2?
How is it transmitted and what is the clinical presentation?
A
herpes simplex virus 2 (HSV-2)
Transmission route:
- sexual contact
- perinatal
Clinical presentation:
- genital herpes
- neonatal herpes
8
Q
What is the name of HHV-3?
How is it transmitted and what is the clinical presentation?
A
varicella zoster virus (VZV)
Transmission route:
- respiratory
Clinical presentation:
- chicken pox
- shingles
9
Q
What is the name of HHV-4?
How is it transmitted and what is the clinical presentation?
A
Epstein-Barr virus (EBV)
Transmission route:
- saliva - known as the “kissing disease”
Clinical presentation:
- mononucleosis - associated with lymphomas & nasopharyngeal carcinoma
10
Q
What is the name of HHV-5?
How is it transmitted and what is the clinical presentation?
A
cytomegalovirus (CMV)
Transmission route:
- congenital
- sexual
- saliva
Clinical presentation:
- mononucleosis in immunocompromised patients
11
Q
What is the name of HHV-6 and HHV-7?
How is it transmitted and what is the clinical presentation?
A
HHV-6 & HHV-7
Transmission route:
- saliva
Clinical presentation:
- roseola infantum (high fever followed by a rash in infants)
12
Q
What is the name of HHV-8?
How is it transmitted and what is the clinical presentation?
A
HHV-8
Transmission route:
- sexual contact
Clinical presentation:
- Kaposi’s sarcoma
13
Q
What is the definition of herpes simplex virus?
How common is it?
A
this describes disease resulting from HSV1 or HSV2 infection
it is very common with 90% of adults seropositive for HSV1 by 30 years
it can be asymptomatic
14
Q
What is the presentation of HSV-1 like?
A
herpes virus - think VESICULAR rash
- gingivostomatitis, cold sores (herpes labialis)
-
herpetic whitlow
- painful vesicular lesions on the hands / fingers
-
eczema herpeticum
- looks like eczema, but rash is vesicular
- herpes simplex meningitis, encephalitis
- systemic infection
- keratoconjunctivitis
15
Q
What is the presentation of HSV2 like?
A
this presents as genital herpes, which is chronic and life-long
- flu-like prodrome
- vesicles / papules around the genitals & anus
- shallow ulcers
- urethral discharge
- dysuria
- fever and malaise
16
Q
What is the aetiology for herpes simplex virus?
A
- the virus becomes dormant following primary infection
- it travels to the trigeminal / sacral root ganglia and stays there
- reactivation may occur in response to stress or immunosuppression (HIV)
17
Q
What are the 2 phases involved in herpes simplex virus infection?
A
Latent phase:
- chronic infection where infectious virions are not produced
- the virus is within the trigeminal/sacral root ganglion
- there are no symptoms
Lytic phase:
- there is viral replication and transport of the virus to the skin
- this is active infection that produces symptoms
18
Q
What investigations are carried out for herpes simplex virus?
What is involved in the management?
A
Investigations:
- usually a clinical diagnosis
- may consider viral culture / HSV PCR (not usually done)
Management:
- topical, oral or IV acyclovir depending on severity of presentation
19
Q
What is the definition of varicella zoster infection?
A
- the primary infection is varicella (chickenpox)
- reactivation of the dormant virus in the dorsal root ganglia causes zoster (shingles)
this usually occurs due to stress and presents in a dermatomal distribution
20
Q
What is the epidemiology of varicella zoster virus like?
A
- chickenpox has a peak incidence between 4 to 10 years
- shingles has a peak inidence of > 50 years
- around 90% of adults are VZV IgG positive
21
Q
What is the presentation of chickenpox like?
A
- prodromal malaise
- mild pyrexia
- generalised pruritic vesicular rash
- this predominantly affects the face and trunk
- contagious from 48 hours before the rash and until all the vesicles have crusted over (within 7 - 10 days)
22
Q
What is the presentation of shingles like?
A
- may occur due to stress
- there is tingling in a dermatomal distribution
- this is followed by painful skin lesions
- it is unilateral due to a dermatomal distribution (only in one of the trigeminal nerves)
- it can affect any dermatome, but is usually on the trunk
- recovery within 10 - 14 days
23
Q
What are the investigations for varicella zoster virus?
How is the treatment different for chickenpox in adults and children?
A
- no investigations are performed - it is a clinical diagnosis
Children:
- supportive treatment to relieve the symptoms
- Calamine lotion to treat itching
- analgesia
- antihistamines
Adults:
- treatment is aimed at treating the virus, rather than the symptoms
- consider aciclovir, valaciclovir or famciclovir if within 24 hours of rash onset
- no treatment is given if the patient presents after 24 hours
24
Q
What is the treatment for shingles?
A
- 1st line treatment involves valaciclovir or famciclovir
- 2nd line treatment involves aciclovir
if within 72 hours of appearance of the rash, given for 7 days
25
What is involved in the prevention of varicella zoster?
**VZIG** may be indicated in:
* **_immunosuppressed_** individuals
* **_pregnant women_** exposed to varicella zoster
* this virus can have teratogenic effects
chickenpox vaccine is licensed in the UK, but no guidelines are available for appropriate use
26
What can shingles lead to in 15% of elderly patients?
**_postherpetic neuralgia_**
this is **neuropathic (nerve) pain** that occurs due to damage to a peripheral nerve caused by reactivation of VZV
nerve pain tends to be confined to a **single dermatome**
27
What are the acute complications of chickenpox?
* bacterial sepsis
* pneumonia
* encephalitis
* haemorrhagic complications
complications are rare in healthy children
28
What are some of the acute complications of shingles?
* meningoencephalitis
* myelitis
* cranial nerve palsies
* vasculopathy
* gastrointestinal ulcers
* pancreatitis
* hepatitis
complications can also occur without the rash
29
What are the main clinical features of infectious mononucleosis?
* **pharyngitis**
* **lymphadenopathy** (swollen lymph nodes)
* **splenomegaly** (enlarged spleen)
* there may also be hepatitis
* **_atypical lymphocytes_** will be seen
30
In what types of infections are neutrophils and lymphocytes most commonly seen?
* **_neutrophils_** are mostly seen in **_bacterial infections_**
* **_lymphocytes_** are mostly seen in **_viral infections_**
31
What is the definition of infectious mononucleosis and how common is it?
How is it spread?
it is a **clinical syndrome** caused by **_primary EBV infection_**
## Footnote
* (also known as glandular fever)*
* it affects **90-95%** of people at some point in their lives
* EBV is spread by **_saliva / respiratory droplets_**
* it infects **_B lymphocytes_** and there is incorporation of viral DNA into host DNA
32
What is the presentation of infectious mononucleosis like?
* **fever**
* **_jaundice_** due to **hepatosplenomegaly**
* **_tonsillar exudates_** due to **pharyngitis**
* **lymphadenopathy** affecting the **_posterior cervical nodes_**
33
What "triangle" is used to diagnose infectious mononucleosis?
* there should be fever, pharyngitis and lymphadenopathy on a background of atypical lymphocytosis
34
What investigations are done for infectious mononucleosis?
* **FBC** will show **_lymphocytosis_** which is highest in **week 2-3**
* **blood film** will show **_atypical lymphocytosis_**
* **_Monospot test_** is performed to look for **heterophile antibodies**
* **EBV specific antibodies**
35
What is involved in the management for infectious mononucleosis?
* management involves **supportive care** with **_paracetamol or ibuprofen_** (anti-inflammatory + analgesics)
* **_corticosteroids_** may be indicated for **severe cases**
* e.g. haemolytic anaemia, severe tonisillar swelling, obstructive pharyngitis
36
What is contraindicated in infectious mononucleosis and why?
antibiotics should not be given, especially **_amoxicillin_** or **_ampicillin_**
these cause a **widespread maculopapular rash**
37
What are the 3 components of the EBV specific antibody test?
* EBV viral capsid antigen (VCA) **_IgM_**
* indicates **current infection**
* EBV VCA **_IgG_**
* indicates **past infection**
* Epstein-Barr nuclear antigen **_(EBNA)_**
* appears **6 - 12 weeks after** onset of symptoms
38
How can the levels of VCA IgM, VCA IgG and EBNA IgG determine whether someone has had EBV or not?
* in an **_early_ primary infection**, there will only be **_VCA IgM_**
* in an **_acute_ primary infection**, there will be **_VCA IgM & IgG_**
* if someone has **had EBV in the _past_**, they will have **_VCA IgG & EBNA_**
39
How does HIV replicate?
* it attaches to the cell and uses **reverse transcriptase** and **integrase** to become part of the nuclear genome
* it can then produce **viral proteins** and replicate
40
What are the ways in which HIV can be transmitted?
* through **sexual contact**
* during **pregnancy**, **childbirth** & **breastfeeding**
* **injection drug use**
* **occupational** exposure
* **blood transfusion** or **organ transplant**
41
What are the 4 stages of untreated HIV infection (4Fs)?
***_1 - Flu-like:_***
* presents with **fever, myalgia, fatigue** & flu-like symptoms after intial infection
***_2 - Feeling fine:_***
* the virus is **slowly replicating** and during this time there are **no symptoms**
***_3 - Falling count:_***
* virus starts **destroying CD4 cells** and their numbers dwindle
***_4 - Final crisis:_***
* CD4 cells are so low that they **cannot fight other infections**
* this is an **immunocompromised patient** with **AIDS**
42
What is the reason for the presentation of HIV?
What are 3 common presentations of diseases that occur in someone with HIV?
HIV presentation is due to complications arising from having **_low levels of CD4+ T cells_**
* **toxoplasmosis** infection presents with **ring-enhancing lesions** on CT-head
* **CMV retinitis i**s caused by herpes virus
* **diffuse patchy pneumonia** caused by **pneumocystitis (PCP)**
43
What is hairy leukoplakia?
What causes it and who is affected?
* **_irregular, white, painless plaques_** on the **_lateral tongue_** that **cannot be scraped off**
* mediated by **_EBV_**
* occurs in **HIV-positive patients** and **organ transplant recipients**
44
What is the definition of candidiasis?
Who tends to be affected and what causes it?
it is a **fungal infection** caused by **_Candida species_ (*Candida albicans*)** = **_thrush_**
* oral colonisation ranges from 40-70% of healthy adults and children
* higher rates of infection are seen in children with carious teeth and adults with dentures
* it is caused by a **dimorphic fungus**
45
What are the symptoms of candidiasis and who tends to be affected by them?
* **_oral candidiasis_** and **_oesophageal thrush_** affects **immunocompromised** patients
* this presents with a white exudate that can be scraped off
* **_vulvovagintis_** affects **diabetics** and people who have used **antibiotics** recently
* diaper rash
* **_infective endocarditis_** affects **IV drug users**
* **_disseminated candidiasis_** is most common in **neutropenic patients**
46
What are the signs and symptoms of candidiasis?
* **oral candidiasis** and **oesophageal thrush**
* presents with **_dysphagia_**
* **vulvovaginitis / balanitis**
* presents with **_thick discharge,_** **_itching, redness, soreness_**
* **disseminated candidiasis**
* presents with **_fever, hypotension +/- leucocytosis_**
47
What are the investigations for candidiasis?
it is usually a **_clinical diagnosis_** and swabs are not routinely recommended
other investigations may be performed to **exclude differentials or risk factors:**
* urinalysis (UTI)
* random or fasting blood glucose (diabetes)
* glucose tolerance test (diabetes)
* HIV antibody test
* vaginal pH test (to exclude STIs)
48
What is Kaposi's sarcoma and how does it present?
* it is an **AIDS-defining condition** that is caused by **_HHV-8_**
* it presents as a **_pink or violaceous (purple) patch_** on the **skin** or in the **mouth**
49
What are other HIV-associated tumours?
* **_squamous cell carcinoma_**
* this is particularly **cervical** or **anal** and due to **HPV**
50
What are the first line investigations for HIV?
* **_ELISA_** - confirmed with Western blot
* serum HIV rapid test
* serum HIV DNA PCR in infants
* **CD4 count**
* this indicates immune status and assists the staging process
51
What is the definition of tonsillitis?
How common is it?
***acute infection of the _parenchyma_ of the _palatine tonsils_***
it may occur **in isolation** or as part of **generalised pharyngitis**
it is **_very common_** and is more common in children **aged between 5 and 15**
52
What are the common bacterial and viral causes of tonsilitis?
***_Viral:_***
* most common are **rhinovirus**, **coronavirus** & **adenovirus**
* associated with **IM infection**
***_Bacterial:_***
* Group A streptococci
* *Mycoplasma pneumoniae*
* *Neisseria gonorrhoea*
53
What are the signs and symptoms of tonsillitis?
* **pain on swallowing**
* fever **\> 38**
* **_tonsillar exudate_**
* **sudden onset** of a **sore throat**
* tonsillar **erythema** and **enlargement**
* **_anterior_ cervical lymphadenopathy**
54
What are the Centor criteria for tonsillitis and how do they determine what investigations should be done?
* **_tonsillar exudates_** present
* **_fever_** \> 38
* **_anterior cervical lymphadenopathy_**
* **_absence_ of a cough**
* if score is **2 or less**, then the cause is likely to be viral and **no investigations** are performed
* if the score is **_3 or more_** then a **_rapid streptococcal antigen test_** is performed
55
What is the definition of the common cold?
How common is it?
**mild, self-limiting,** **_viral_**, **_upper_ respiratory tract infection** characterised by **_nasal stuffiness_** and **_discharge_**, **sneezing, sore throat** and **cough**
it is very common and adults experience around **2-3 each year**
56
What are the most common causes of the common cold?
* rhinoviruses (50%)
* coronavirus (10-15%)
* influenza (5-15%)
* parainfluenza (5%)
* respiratory syncytial virus (5%)
57
What are the investigations for the common cold?
What is involved in the management?
* usually it is a **clinical diagnosis** and no investigations are done
* consider FBC, throat swab, sputum culture, CRP, CXR
* management is with **_supportive care_**
* hydration
* analgesics
* antipyretics
* decongestant (oxymetazozline nasal, ipratropium nasal)
* +/- antihistamine, antitussive
58
What are the signs and symptoms of a common cold?
* runny / blocked nose
* sneezing
* sore throat
* cough
* headache
* malaise and fever
* symptoms usually clear within **7 to 10 days**
59
What is the definition of an abscess?
What usually causes it?
a **_collection of pus_** that has built up within a **_tissue_, _organ**_ or _**confined space_ walled off by fibrosis**
it is usually caused by **_bacterial infection_**
rarely, it can be caused by **parasites** (developing world) or **foreign substances**
60
What is an external abscess and what usually causes it?
an abscess on the **_skin surface_** that is either **cutaneous** or **subcutaenous**
it is usually caused by ***Staphylococcus aureus***
61
What are the signs and symptoms of an external abscess?
* erythema
* hot
* oedema
* pain
* loss of function
62
Where do internal abscesses tend to be found?
* lungs
* brain
* teeth
* kidneys
* tonsils
* perianal abscesses (common in IBD and diabetes)
* incisional abscesses
63
What are the signs and symptoms of an internal abscess?
the patient is often **_systemically unwell_** with **pain** and **fever**
64
What are the investigations performed for an abscess?
* history
* examination
* observations
* it is usually a **clinical diagnosis**, however **USS** can be used to help with diagnosis
65
What is involved in the management for an uncomplicated abscess?
for uncomplicated skin or soft tissue abscesses:
* **aspiration**
* **incision and drainage**
there is no need for antibiotics
66
What is involved in the management for severe abscesses?
for severe abscesses, multiple sites of infection, rapid disease progression, cellulitis & sepsis:
* **antibiotics**
* **incision and drainage**
* **excision** in severe cases
67
