Derm - Infections Flashcards
Impetigo, Cellulitis, Ersipelas, Necrotising Fasciitis, Measles, and even more infections!!!!
1
Q
What is Impetigo?
A
Highly infectious superficial skin infection that typically affects children
2
Q
What are the two most common causative organisms of impetigo?
A
Staph. aureus ± Strep. pyogenes (Group A strep)
3
Q
Which age group is most commonly affected by impetigo?
A
Children
4
Q
Where does the infection occur in impetigo?
A
Immediately below the surface, in the stratum corneum
- outermost layer of the epidermis in the skin
5
Q
What allows bacteria to enter the skin in impetigo?
A
A small skin defect
6
Q
How does impetigo spread?
A
Highly contagious, spread via discharge and scratching
7
Q
Where do impetigo lesions commonly appear?
A
Face
8
Q
What classic description is used for impetigo lesions?
A
Golden crusty lesion with an erythematous base
9
Q
When would you send a bacterial swab for culture and sensitivity?
A
If the impetigo is
(1) severe
(2) recurrent
(3) unresponsive to treatment
(4) MRSA is suspected
10
Q
What is the first-line treatment for localised impetigo?
A
Topical fusidic acid for 7 days
11
Q
When are oral antibiotics required for impetigo, and why?
A
In severe impetigo or when streptococci are present
This is to avoid post-streptococcal glomerulonephritis
- Kidney Infection
12
Q
What is the treatment for extensive or severe impetigo?
A
- Oral flucloxacillin or clarithromycin (500mg QDS) + topical fusidic acid
13
Q
How is impetigo normally treated?
A
Tropical antibiotics
14
Q
A 6-year-old girl is brought into the general practice by her father. He is concerned about a new rash that has developed around his daughter’s mouth. Apart from this rash, she is well in herself. The rash can be seen below:
[ GOLD CRUSTY LESIONS]
Given the likely diagnosis, what advice can you give the father regarding his daughter returning to school?
A
She can return once all lesions have crusted over or after 48 hrs after starting antibiotic therapy as she is no longer contagious
15
Q
What is the first line treatment for mild impetigo?
A
Either fusidic acid or mupirocin.
The treatment duration is 5-7 days, after which flucloxacillin is given
15
Q
A 2-year-old boy is brought to the GP by his mother due to a three-day history of yellow crusting around his mouth. There is mild erythema around the mouth but it is very localised and has no vesicles. He has no known allergies. The GP prescribes topical fusidic acid 2%. One week later, the boy is brought back with worsening symptoms. The crusting is now more widespread across his face. However, he is afebrile and systemically well.
What is the next best management option? and why?
A
Oral flucloxacillin
= The first-line oral antibiotic is flucloxacillin if the patient still has it after 7 days.
For patients who are penicillin allergic, macrolides such as clarithromycin or erythromycin may be used
16
Q
When is Topical fusidic acid first line instead of Topical hydrogen peroxide?
A
If hydrogen peroxide is not suitable
(eg, broken skin, eczema, sensitivity).
If impetigo is more severe or widespread, or the patient is at risk of complications.
17
Q
A 4-year-old child presents to your GP clinic with multiple small bullae on the face and trunk, which have ruptured, leaving areas of honey-coloured crusting. He is allergic to penicillin. The lesions are not widespread. The child has no systemic symptoms, such as fever or malaise.
What is the most appropriate management for this child?
A
Oral clarithromycin
= bullous impetigo almost always requires oral antibiotics, even if it is not widespread
18
Q
Define Cellulitis
A
Invasion of the dermis and subcutaneous fat
= deeper skin infection
19
Q
What are the two most common causative organisms of cellulitis?
A
Strep. pyogenes ± Staph. aureus
20
Q
Which patient group is more prone to cellulitis?
A
Diabetics
21
Q
Which part of the body is most commonly affected by cellulitis?
A
Legs
22
Q
How does the skin appear in cellulitis?
A
- Macular
- Hot erythema with ill-defined margins
- Often spreading
23
Q
What systemic symptoms can occur in cellulitis?
A
Fever, rigors, nausea
24
How is cellulitis usually diagnosed?
Clinically
25
When would you consider cultures (eg, blood, wound swabs, blister fluid) for those with cellutis?
If the presentation is atypical, the patient is very unwell, or not responding to treatment
26
What non-pharmacological treatments help cellulitis?
Rest, elevation, analgesia, splint
27
What is the first-line oral antibiotic for cellulitis?
Flucloxacillin 0.5–1g QDS for 7 days
28
What is an alternative oral antibiotic for penicillin-allergic patients?
Doxycycline 100mg BD for 7 days
29
What antibiotic is used for severe cellulitis?
IV flucloxacillin (or vancomycin if allergic)
30
Which layers of the skin are usually involved in cellulitis?
Dermis and subcutaneous fat
31
When initiating treatment for cellulitis, which measure should be undertaken to monitor its progress?
Draw a line around the affected area to look for whether the area grows in size or is improving with therapy
32
What is the Eron classification used for?
Assessing cellulitis severity
33
What defines Class I cellulitis?
No systemic toxicity, no uncontrolled comorbidities
34
What defines Class II cellulitis?
Systemically unwell or has comorbidities
35
What defines Class III cellulitis?
Significant systemic upset or limb-threatening infection
36
What defines Class IV cellulitis?
Sepsis or life-threatening infection
37
NICE guidelines recommend that any immunocompromised patient with cellulitis should be managed with what?
in hospital with intravenous antibiotics
38
A 32-year-old woman who is 26 weeks pregnant presents to the GP with a red right calf. This has come on over the past 2 days and has become more warm and red. She has no past medical history and is allergic to penicillin. She is usually mobile and does yoga daily. On examination, there are diffuse, poorly demarcated, erythematous skin changes over the right calf.
What is the most appropriate management, and why isn't it flucloxacillin?
Prescribe erythromycin
= Flucloxacillin is the first-line antibiotic for cellulitis in non-pregnant patients without penicillin allergy
39
Define Erysipelas
Superficial form of cellulitis localised to dermis and lymphatic system
40
Where is Erysipelas most commonly found?
Face
41
How does Erysipelas appear on the skin?
Spreading, well-demarcated erythematous plaque
42
What is the causative organism for erysipelas?
Strep. pyogenes
43
What associated symptoms are common in erysipelas?
Fever and systemic upset
44
What is the first-line treatment for erysipelas?
Flucloxacillin (oral)
45
What is used if the patient is unable to take oral medication or is severely unwell?
IV flucloxacillin
46
What are the clinical features of erysipelas?
(1) Borders are sharply defined and affected skin is raised, swollen, firm, erythematous and pruritic
(2) Commonly affects the lower limbs. If the face is involved can have 'butterfly' distribution over the cheeks and the bridge of the nose
47
What is the commonest cause of erysipelas?
Group A beta-hemolytic streptococcus
48
An 87-year-old woman has had a red, hot, swollen left foot for 5 days. You review her on a home visit and diagnose cellulitis. She has a past medical history of recurrent cellulitis, T2DM and HTN. She has a penicillin allergy, having had an anaphylactic reaction 3 years ago. She is on metformin, amlodipine and atorvastatin.
Which is the most appropriate antibiotic to prescribe?
Clindamycin
49
Define Necrotising Fasciitis
A rapidly progressive infection resulting in extensive necrosis of superficial fascia and overlying subcutaneous fat that can develop into a life-threatening condition within hours
50
How does the infection typically enter the body?
Through a break in the skin, such as a cut or burn
50
Which conditions increase the risk of necrotising fasciitis?
(1) Poor immune function
(2) Obesity
(3) PWIDs (people who inject drugs)
(4) Peripheral arterial disease
51
What systemic symptoms are associated with necrotising fasciitis?
Fever, chills, altered mental status
52
What is the initial skin presentation of necrotising fasciitis?
Diffuse erythema, often resembling cellulitis that doesn't respond to antibiotics
53
What type of pain is common in necrotising fasciitis?
Disproportionate pain
54
What physical signs are seen in necrotising fasciitis?
1. Crepitus
2. Purple skin discolouration
55
What is the first-line treatment for necrotising fasciitis?
Surgical debridement + antibiotics/ washout
56
An 87-year-old gentleman from a nursing home is admitted with sudden deterioration. His past medical history includes an open appendicectomy, T2DM and Alzheimer's disease. His nursing staff report he has been drowsy for the past few hours and is complaining of intense generalised pain. They have noted that his urine output has decreased over the past night.
The patient is hypotensive, tachypneic and tachycardic. A thorough examination of the patient is performed after initial resuscitation. He is found to have an indwelling catheter. Significant erythema is noted around the sacrum and perineum. A small patch of black skin is noted in the perineum, and his nursing staff deny having seen it before.
What is the most appropriate management?
Immediate surgical debridement
57
When would Clostridium perfringens be first line for necrotising fasciitis?
(1) Presence of gas formation (crepitus) or gas gangrene
(2) Rapid progression of infection
(3) Trauma or injury involving contaminated wounds, especially in situations like deep puncture wounds, burns, or surgical sites
58
What type of virus causes measles?
Paramyxovirus
58
What is the characteristic rash in measles?
Maculopapular rash with Koplik spots on the inside of the cheek
59
What is the classic triad of symptoms for measles?
Conjunctivitis, cough, rash
60
What is the first step in managing measles?
Supportive care only
61
What are some common complications of measles?
Otitis media, diarrhoea, pneumonia
62
What are severe complications of measles?
(1) Corneal ulceration
(2) Acute renal failure
(3) Encephalitis - MAJOR
(4) Otitis media
(5) Pneumonia
(6) Febrile seizures
63
What complications can measles cause in pregnancy?
Premature labour, fetal loss
64
What are the white spots found on the inside of a child's mouth with measles known as?
Koplik spots
65
How is the measles infection spread?
Droplets of saliva
65
A 3-year-old boy was brought to the GP by his mother after two days of a fever and sore eyes. The GP looked inside the child’s mouth and noticed some white spots on the inside of his cheeks. The child had not been vaccinated.
What is the mode of transmission for this infection?
Respiratory droplets
66
When would IgM and IgG serology or RNA detection by PCR be used when the patient presents with measles?
serology - when the onset of the rash occurred over 3 days ago
PCR - between 24 and 72 hours following the onset of the rash
67
How does measles present?
(1) Measles presents with a classic triad of cough, coryza and conjunctivitis, along with high fever.
(2) An erythematous maculopapular rash develops a few days later, which starts from behind the ears and spreads down to the trunk and limbs.
(3) This is in contrast to the fine macular rash of rubella, which classically spares the limbs.
(4) There may be small white spots (koplik spots) visible in the buccal mucosa preceding the rash
68
What are the symptoms of measles infection?
1. Fever typically over 40 degrees
2. Conjunctivitis
3. Coryzal symptoms
4. Koplik spots (grey spots)
69
His mother reports a 4-day history of non-productive cough, runny nose, and red eyes, followed by a red blotchy rash on his head, face, chest, and arms. She also noticed white spots in his mouth a few days ago. He is normally healthy, takes no medications, and has not had vaccinations due to his parents' concerns about their safety.
On examination, the boy appears unhappy but well.
Vital signs: SpO2 99%, RR 20, HR 82, capillary refill 2 seconds, temp 39.5°C.
He has an erythematous maculopapular rash on his head, neck, torso, and limbs.
What kind of vaccine would have prevented this child's infection?
Live attenuated vaccine
MMR vaccine
70
A 15-year-old girl is brought to the general practice by her father. She has been unwell for the last 3 days with a high fever, cough, runny nose and red eyes.
Today she has developed a red bumpy rash on her face and behind the ears.
Her father explains that she was not vaccinated as a child due to parental choice.
Given the likely diagnosis, how long should they be excluded from school for?
4 days from the start of the rash
71
What virus causes rubella?
Rubella virus (Togaviridae family)
72
What is the characteristic rash in rubella?
Pink-red maculopapular rash
(similar distribution to measles, but less serious and shorter duration)
73
What virus causes chickenpox (Varicella)?
Varicella-zoster virus (VZV) (Herpesviridae family)
73
How is rubella prevented?
MMR vaccine
(measles, mumps, rubella)
74
How is chickenpox different in adults compared to children?
It is severe in adults and mild in children
75
When is chickenpox infectious and can chickenpox lead to shingles?
The patient is infectious until all lesions have crusted over and yes, shingles is a reactivation of previous chickenpox infection
76
What is the treatment for chickenpox (Varicella)?
Aciclovir (not used in immunocompromised patients)
77
What is Ramsey Hunt Syndrome?
Herpes zoster oticus — a complication of shingles affecting the V2 facial nerve
78
What is the treatment for Herpes Simplex Virus infections?
Aciclovir
79
[Picture of melanoma]
What is the treatment?
Incision biopsy
80
What is an exanthema?
A rash associated with systemic features (eg, headache, fever, malaise)
81
What is exanthema often associated with?
Upper respiratory tract infections (URTI)
82
How should delivery be managed if a woman contracts primary herpes simplex from week 34?
Offer a Caesarian section
83
If primary herpes is contracted in early pregnancy, what is the recommendation for management?
Aciclovir from 36 weeks gestation onwards through to delivery
84
An 80-year-old male presents to the emergency department with a one-day history of blurred vision in his right eye. He also finds eye movements painful. Swelling and erythema are noted in the upper eyelid, and the sclera is red. In addition, there are several painful red vesicles on the right side of his face. His pupils are equal and reactive to light.
His observations are normal.
What treatment is indicated?
Aciclovir
= herpes zoster ophthalmicus
trigeminal nerve
85
A 27-year-old female rings her GP practice since she is 29 weeks pregnant and yesterday had a visit from a friend and her 3-year-old child. Today, the child developed a vesicular itchy rash consistent with chicken pox. The patient thinks she previously had chicken pox but can't remember. The GP organises varicella zoster antibody testing which comes back positive.
What is the next step for managing this patient?
Reassure that no further action is required
= This woman has evidence of immunity against chicken pox in the form of varicella-zoster antibodies
86
What is the triad of congenital rubella syndrome?
(1) Sensorineural deafness
(2) Eye problems - cataracts, retinopathy
(3) Congenital heart defects - PDA, pulmonary artery stenosis
87
Although rubella infection is generally mild, infection in nonimmune pregnant women puts the fetus at risk for congenital rubella syndrome, which is characterised by what?
cataracts, brain damage and deafness
88
A 3.2kg baby boy was born yesterday at 38 weeks without complications during delivery to a 28-year-old mother of South-East Asian descent. The midwife was worried about a number of non-blanching nodules, which are purple in colour, and a number of visible petechiae, so has called for an urgent paediatric review. On examination, hepatosplenomegaly and a heart murmur best auscultated in the left infraclavicular area are noted. A cataract is also noted in the left eye. The baby's mother admits she doesn't know about her vaccination history as she moved to the UK when she was 22 and hasn't attended much of her antenatal care during the pregnancy.
What is the most likely cause of this newborn's presentation?
Rubella virus
89
A 5-year-old girl presents with a rash that started on her face and spread to her trunk. She also has a low-grade fever and swollen lymph nodes behind her ears.
Which of the following viruses is most likely causing her symptoms?
Rubella virus
90
A new mother has just given birth to a baby boy. The child has a low birth weight and a petechial rash. Upon review, the boy is found to have cataracts and sensorineural hearing loss. The mother mentions contracting an illness during her first trimester, in which she had a mild fever, and a rash which started on the face and then spread to the whole body. This rash disappeared after 5 days.
A positive result of which immunoglobulin in a blood sample from the baby will confirm the likely diagnosis?
IgM
91
A 22 year old male presents to his GP. He is concerned as he went to a party yesterday and was in contact with his nephew, who he has now discovered has chickenpox. He has never had chickenpox before and has not been vaccinated. He suffers from severe asthma and is taking long term oral corticosteroids as he awaits specialist review for consideration of biologic therapies.
What is the next step in the management of this patient?
Oral aciclovir in one week, for 7 days
92
A 67 year old male on the vascular ward is reviewed. They have longstanding poorly controlled type 2 diabetes, obesity, foot ulcers, hypertension and hypercholesterolaemia.
They complain of pain in their 3rd toe, where they recently had an ulcer. On examination, there is acute tenderness and crepitus on palpation and spreading erythema. The patient is febrile, other observations are normal.
What is the most likely causative organism?
Clostridium perfringens infection
93
An 18-year-old boy is brought to the hospital by his mother. He has been unwell with itchy eyes and fevers over the last three days. Today, his mother became concerned when she noticed a rash behind his ears which began to spread over his entire body. She is unsure if he is up to date with his immunisations, and his GP surgery is closed.
On examination, he has white spots on his buccal mucosa and a discrete maculopapular rash.
By what route is this illness spread?
droplets - aroseol
94
What are the key features of Ramsay Hunt syndrome?
(1) Ipsilateral facial palsy
(2) Ear pain
(3) Vesicular eruption around the ear canal
= It affects all regions of one side of the face, including the forehead
95
Erythema infectiosum ('slapped-cheek syndrome') is caused by what?
parvovirus B19
96
A 62-year-old gentleman presents to the emergency department with a new onset left-sided facial palsy. He describes having a painful rash around the ear on the same side as the facial palsy for the past five days. You suspect Ramsay Hunt syndrome. This is a condition caused by which virus?
Varicella zoster virus
97
A patient has grouped vesicles on an erythematous base around the lips. What’s the most likely cause?
HSV-1 (Herpes Simplex Virus) = causes cold sores
98
What viral illness causes a widespread itchy rash that starts on the trunk, with lesions in different stages (papules, vesicles, crusts)?
Chickenpox
99
In what condition would you see velvety, hyperpigmented plaques in skin folds, often linked with insulin resistance?
Acanthosis nigricans
100
A 36-year-old male comes into your clinic with an 8-hour history of a red painful leg. He was jogging in the park when he cut himself on a branch. On examination, his left leg is tender and warm. You diagnose cellulitis and ask the patient if he has any allergies. He responds that he developed a widespread rash to amoxicillin when younger.
What antibiotic do you prescribe?
Clarithromycin
101
Severe cellulitis should be treated with what?
co-amoxiclav, cefuroxime, clindamycin or ceftriaxone
102
A 72-year-old woman presents with a vesicular rash around her left eye. The left eye is red and there is a degree of photophobia. A presumptive diagnosis of herpes zoster ophthalmicus is made and an urgent referral to ophthalmology is made.
What treatment is she most likely to be given?
Oral aciclovir
103
A 28-year-old pregnant woman wishes to receive the measles, mumps and rubella (MMR) vaccination. She has never received any MMR vaccination and is worried that her baby may be infected as a result. She is currently 12 weeks pregnant and there are no sick contacts around her. Do you give it?
Refrain from giving her any MMR vaccination now and at any stage of her pregnancy
104
A 70-year-old female presents to her general practitioner with a vesicular rash affecting the right side of her face and the tip of her nose. She is diagnosed with herpes zoster ophthalmicus (HZO)
What are the likely complications?
conjunctivitis, keratitis, episcleritis, anterior uveitis
105
A 33-year-old patient presents to your general practice with a red, hot, swollen, and painful left shin. He has no significant past medical or medication history. He says it started off as a small red patch 5 days ago but increased in size to cover the whole anterior left shin. On examination, the patient is able to mobilise and weight bear on his left leg.
What is the next most appropriate investigation?
The diagnosis of cellulitis is clinical. No further investigations are required in primary care
= Ultrasound can be done if you suspect necrotizing fasciitis
106
Zoster immunoglobulin is offered to pregnant women exposed to chickenpox when?
the first 20 weeks of their pregnancy
