Infection and Immunology Flashcards
What is an Abscess?
A collection of pus that has built up within the tissue of the body
Can develop anywhere in the body
Most commonly in the skin or inside the body, in an organ or in the spaces between organs
What is the aetiology of Abscesses?
Caused by bacterial infection, parasites, or foreign substances
Bacterial infection is the most common cause, most common causative pathogen is methicillin-resistant Staphylococcus aureus (MRSA)
What is the epidemiology of Abscess?
Common and have become more common in the last few years
What are the presenting symptoms of an Abscess?
Skin abscess: -Swollen, pus-filled lump under the surface of the skin -Symptoms of an infection, such as fever and chills Internal abscess: -Pain in the affected area -Fever -Malaise -Loss of appetite and weight loss
What are the signs of an Abscess on physical examination?
Skin abscess:
- Smooth swelling under skin
- Pain and tenderness
- Warmth and erythema
- White or yellow pus under the skin
Internal abscess:
- Fever
- Pain or swelling in the affected area
- Dependent on the affected area e.g. lung- cough, dyspnoea, liver- jaundice
What are the appropriate investigations for Abscess?
Bloods: -FBC: leukocytosis -CRP/ESR: inflammatory markers Blood culture: positive for organism CT/Ultrasound: visualisation of abscess
What is anaphylaxis?
Acute life-threatening multisystem hypersensivity syndrome caused by sudden release of mast cell- and basophil-derived mediators into the circulation
What is anaphylaxis characterised by?
Rapidly developing life-threatening airway and/or breathing and/or circulation problems
Usually associated with skin and mucosal changes
What is the aetiology of anaphylaxis?
Immunologic: IgE-mediated or immune complex/complement-mediated
Non-immunologic: mast cell or basophil degranulation without the involvement of antibodies (e.g. reactions caused by vancomycin, codeine, ACE inhibitors)
Inflammatory mediators such as histamine cause bronchospasm, increased capillary permeability and
reduced vascular tone, resulting in tissue oedema
What are the common allergens?
PILFERS
Peanuts Insect stings Latex Fish Egg Radiological contrast agents Shellfish
What is the epidemiology of anaphylaxis?
Relatively common
What are the presenting symptoms of anaphylaxis?
Acute onset of symptoms on exposure to allergen (SOB):
Skin (rash, pruritis)
Oedema (lips, face)
Breathing (short of breath, wheezing)
Biphasic reactions occur 1–72 h after the first reaction in up to 20% of patients
What are the signs of anaphylaxis on physical examination?
URTICARIA: Urticaria Reduced BP Tachypnoea Infected conjunctiva and swollen eyes Cyanosis Audible wheeze Rhinitis Increased heart rate Airway swelling
What are the appropriate investigations for anaphylaxis? Interpret the results
The diagnosis of anaphylaxis is made clinically.
1st line:
Serum (mast cell) tryptase (measured within 15 min–3 h after onset of symptoms)= elevated
Histamine levels (measured preferably within 30 min after symptom onset)
Urinary metabolites of histamine (which may remain elevated for several hours after symptom onset)
ABG: elevated lactate
ECG: Non-specific ST ECG changes are common post-adrenaline
What is the management plan for a patient with anaphylaxis?
Oxygen Can Help Anaphylaxis: Oxygen (100%) Chloropheniramine (10mg) Hydrocortisone (100mg) Adrenaline (IM)- 0.5 mL of 1:1,000, can be repeated every 10mins according to response of pulse and BP
Advice: Educate on use of adrenaline pen for IM administration. Provide Medicalert bracelet
What are the possible complications of anaphylaxis?
(RDS)
Respiratory failure
Death
Shock
What is the prognosis for patients with anaphylaxis?
Good if prompt treatment given
What is Behçet’s disease?
A rare disorder that causes blood vessel inflammation throughout the body (vasculitis)
What is the aetiology of Behçet’s disease?
Poorly understood but thought to be an autoimmune condition, may also be due to an infectious trigger
What are the risk factors for Behçet’s disease?
Age: Commonly affects men and women in their 20s and 30s (though can occur at any age)
People from countries in the Middle East and East Asia, including Turkey, Iran, Japan and China, are more likely to develop Behcet’s
Gender: The disease is usually more severe in men
Genes: genetic predisposition
What is the epidemiology of Behçet’s disease?
RARE disorder
Genetic link
Commonly affects men and women in 20-30 year group but is more severe in men
What are the presenting symptoms and signs of Behçet’s disease on physical examination?
Mouth:
-Painful mouth sores (most common sign), begin as raised, round lesions in the mouth that quickly turn into painful ulcers, usually heal in 1-3 weeks, can reoccur
Skin:
Acne-like sores on bodies
-Red, raised and tender nodules on skin, especially on the lower legs
Genitals:
-Red, open sores can occur on the scrotum or the vulva
-Usually painful and can leave scars
Eyes:
-Inflammation in the eye (uveitis) causes redness, pain and blurred vision, typically in both eyes
Joints:
-Joint swelling and pain often affect the knees, ankles, elbows or wrists also might be involved
-Can resolve in 1-3 weeks
Blood vessels:
-Inflammation in veins and arteries can cause redness, pain, and swelling in the arms or legs when a blood clot results
-Inflammation in the large arteries can lead to complications, such as aneurysms and narrowing or blockage of the vessel
Digestive system:
-Abdominal pain
-Diarrhoea
-Bleeding
Brain:
-Headache
-Fever
-Disorientation
-Ataxia
-More severely: stroke
What are the appropriate investigations for Behçet’s disease?
*Pathergy testing:
-subcutaneous skin prick is performed
-formation of pustule within 48 hours
Bloods:
-CRP/ESR: inflammation
-Rheumatoid factor: exclude rheumatoid arthritis
-Anti-neutrophil antibodies: exclude other autoimmune conditions
-HLA-B51
Imaging:
-MR angiography: CNS involvement
-Colonoscopy: from GI symptoms, exclude other pathology, features on colonoscopy are usually distinct, single, deep ulcers
-Upper GI endoscopy
-CT chest/angiography: when haemoptysis occurs to evaluate for pulmonary aneurysm
-Pulmonary angiography
What is the management of Behçet’s disease?
Immunosuppression: corticosteroids
What is candidiasis?
A fungal infection due to any type of Candida (type of yeast)
What is the aetiology of candidiasis?
Candida normally lives on the skin and inside the body, in places such as the mouth, throat, gut, and vagina, without causing any problems. Candida can cause infections if it grows out of control or if it enters deep into the body (bloodstream or internal organs)
Although mucosal disease is common, invasive disease is not, and the primary reason is that Candida species in general are unable to enter intact epithelium
What are the risk factors for candidiasis infections?
Immunosuppressive agents e.g. systemic corticoid steroid use
Current or recent past use of brand spectrum antibiotics
Malabsorption/ malnutrition
HIV infection
Poor oral hygiene (oral candidiasis)
Endocrine disturbances (DM, pregnancy, hypoadrenalism) - reduce effectiveness of immune system
What are the presenting symptoms of candidiasis infections?
Oral: -creamy white/ yellow plaques adherent to oral mucosa -Cracks/ ulcers around the mouth -spotty red areas on the buccal mucosa -burning oral pain -loss of taste -pain while eating or swallowing Vaginal: -vaginal itching or soreness -pain during sexual intercourse -pain/ discomfort when urinating -abnormal vaginal discharge
What are the signs of a candidiasis infection on physical examination?
Rash
Erythema
Visible plaques/ulcers
What are the appropriate investigations for a candidiasis infection?
Superficial smear of the lesion for microscopy: test for candida
Biopsy
Blood culture
FBC: WCC elevated indicates infection
What is Cellulitis?
An acute spreading infection of the skin with visually indistinct borders that principally involves the dermis and subcutaneous tissue
What is Cellulitis usually characterised by?
Erythema Oedema Warmth Tenderness Commonly occurs in an extremity
What is Erysipelas?
A distinct form of superficial cellulitis with notable lymphatic involvement and is raised, sharply demarcating it from uninvolved skin
What is the aetiology of Cellulitis?
Cellulitis develops when micro-organisms gain entry to the dermal and subcutaneous tissues via disruptions in the cutaneous barrier
The most common causative agents are:
-Beta-haemolytic streptococci
-Staphylococcus aureus
What is the epidemiology of Cellulitis?
Cellulitis is a common condition Main risk factors are: -skin break -poor hygiene -poor vascularization of tissue (e.g. diabetes mellitus)
What are the presenting symptoms of Cellulitis?
There may be history of a cut, scratch or injury
Skin discomfort
Periorbital: Painful swollen red skin around eye
Orbital cellulitis: Painful or limited eye movements, visual impairment
What are the signs of Cellulitis on physical examination?
Lesion: -Erythema -Oedema -Warm tender indistinct margins *Pyrexia may signify systemic spread Exclude abscess: Test for fluid thrill or fluctuation- aspirate if pus suspected Periorbital: -Swollen eyelids -Conjunctival injection Orbital cellulitis: -Proptosis (protrusion of the eyeball) -Impaired acuity and eye movement Test for relative afferent pupillary defect, visual acuity and colour vision
What are the appropriate investigations for Cellulitis?
Bloods: WCC, blood culture
Discharge: Culture and sensitivity
Aspiration: As it is often non-purulent, it is not usually necessary
CT/MRI scan: When orbital cellulitis is suspected (to assess the posterior spread of infection)
What is the management of Cellulitis?
Medical:
-Oral penicillins (e.g. flucloxacillin, benzylpenicillin, coamoxiclav)
-Tetracyclines are effective in most community acquired cases
-In the hospital- intravenous use may be necessary
Surgical:
-Orbital decompression may be necessary in orbital cellulitis(emergency)
Abscess: Abscesses can be aspirated, incised and drained or excised completely
What are the complications of Cellulitis?
Sloughing (shedding) of overlying skin Localized tissue damage In orbital cellulitis, there may be permanent vision loss and spread to brain Abscess formation Meningitis Cavernous sinus thrombosis
What is the prognosis of Cellulitis?
Good with treatment
What is conjunctivitis?
Inflammation of the lining of the eyelids and eyeball
What is the aetiology of conjunctivitis?
Caused by: Bacteria Viruses Allergic or immunological reactions Mechanical irritation Medicines
Bacterial and viral conjunctivitis is highly contagious
What are the risk factors for conjunctivitis?
Exposure to infected person Infection in one eye Environmental irritants Allergen exposure Mechanical irritation Chronic contact lens useful Camps/ swimming pools
What are the presenting symptoms of conjunctivitis?
Watery discharge (viral) Ropy/ mucoid discharge, itching (allergic) Purulent discharge (bacterial) Eyelids stuck together in the morning (bacterial and viral)
What are the signs of conjunctivitis on physical examination?
Tender pre-auricular lymphadenopathy (more common in viral than bacterial infection)
Conjunctival follicles- round collections of lymphocytes
What are the appropriate investigations for conjunctivitis?
1st line:
Rapid adenovirus immunoassay- 2 visible lines equal positive
Others:
Cell culture/ Gram stain/ PCR- isolate viral or bacterial strains, amplify DNA
What is Encephalitis?
Inflammation of the brain parenchyma
What is the aetiology for Encephalitis?
In the majority of cases encephalitis is the result of a viral infection. Most common in the UK is HSV.
Other: bacteria (syphilis, staph A), immunocompromised (Cytomegalovirus, toxoplasmosis, Listeria)
What is the epidemiology of Encephalitis?
Annual UK incidence is 7.4 in 100,000
What are the presenting symptoms for Encephalitis?
Usually encephalitis is a mild self-limiting illness.
Subacute onset (hours to days) headache
Fever
Vomiting
Neck stiffness, photophobia, i.e. symptoms of meningism (meningoencephalitis) with behavioural changes
Drowsiness and confusion
There is often a history of seizures
Focal neurological symptoms (e.g. dysphasia and hemiplegia) may be present
It is important to obtain a detailed travel history
What are the signs of Encephalitis on physical examination?
Reduced level of consciousness with deteriorating GCS, seizures, pyrexia.
Signs of meningism: Neck stiffness, photophobia, Kernigs test positive.
Signs of raised intracranial pressure: hypertension, bradycardia, papilloedema.
Focal neurological signs.
Minimental examination may reveal cognitive or psychiatric disturbances.
What is Kernigs sign?
Positive when the thigh is flexed at the hip and knee at 90 degree angles, and subsequent extension in the knee is painful (leading to resistance)- indicating the presence of meningitis or subarachnoid haemorrhage
What are the appropriate investigations for Encephalitis?
Blood: FBC (raised lymphocytes), U&E (SIADH may occur), glucose (compare with CSF glucose), viral serology, ABG.
MRI/CT: Excludes mass lesion. HSV produces characteristic oedema of the temporal lobe on MRI.
Lumbar puncture: raised Lymphocytes,monocyte and protein, glucose usually normal. Viral PCR is first line.
EEG: May show epileptiform activity, e.g. spiking activity in temporal lobes
What is Epididymitis and Orchitis?
Epididymitis is characterized by acute unilateral scrotal pain and swelling of less than 6 weeks’ duration.
The pain usually begins at the epididymis and can spread to the entire testicle (epididymo-orchitis)
What is the aetiology of Epididymitis and Orchitis?
- Among sexually active men of all ages, STI pathogens including Chlamydia trachomatis and Neisseria gonorrhoeaeare common causes of epididymitis
- In older men (>35 years), infection may be due to non-sexually transmitted infection with common uropathogens, such as Escherichia coli and Enterococcus faecalis
What is the epidemiology of Epididymitis and Orchitis?
Epididymitis is the most common cause of scrotal pain in adults with an incidence of 25–65 cases per 10,000 adult males per year
Over half of men and boys with epididymitis also have orchitis.
-Isolated orchitis is rare: the commonest cause is mumps infection, although it can also be caused by other viral infections
What are the presenting symptoms of Epididymitis and Orchitis?
Gradual onset (unlike testicular torsion)
Unilateral scrotal pain and swelling
Other symptoms: fever, dysuria
What are the signs of Epididymitis and Orchitis on physical examination?
Diffuse enlargement of the testis
Erythema of the scrotal skin
Swelling for < 6 weeks: otherwise indicates chronic inflammation
What are the appropriate investigations for Epididymitis and Orchitis?
*first catch urine sample
Urethral swab: highly sensitive and specific for documenting urethritis and the presence or absence of gonococcal infection (look for urethral discharge)
Urine dipstick test: positive leukocyte esterase test (urethritis and lower urinary tract infection)
Urine microscopy: WBC
Urine culture: isolate causative organism
Colour duplex ultrasound: done in patients with signs suggestive of abscess formation or possible testicular torsion and infarction; epididymis is enlarged and hyperaemic (increased blood flow)
Consider STI screen
What is the management for Epididymitis and Orchitis?
If <35yrs;
-Doxycycline 100mg/12h (covers chlamydia; treat sexual partners)
-If gonorrhoea suspected add ceftriaxone 500mg IM stat. If >35yrs (mostly non-STI) associated UTI is common:
-Ciprofloxacin 500mg/12h or ofloxacin 200mg/12h
*Antibiotics should be used for 2–4wks
Also: analgesia, scrotal support, drainage of any abscess.
What are the complications of Epididymitis and Orchitis?
(usually of chronic disease, more commonly associated with uropathogen enteric organisms than sexually transmitted organisms) include: Chronic pain Reactive hydrocele Abscess formation Infarction of the testicle Testicular atrophy Reduced fertility
What is the prognosis of Epididymitis and Orchitis?
In men with infectious acute epididymitis, symptoms usually resolve rapidly following the initiation of appropriate antibiotic therapy
RARE CASES: particularly in STIs-epididymal obstruction/testicular atrophy and subsequent infertility problems
What is Gastroenteritis?
Acute inflammation of the lining of the GI tract, manifested by nausea, vomiting, diarrhoea and abdominal discomfort
What is Infectious Colitis?
Inflammation of the colon due to a virus or bacteria
What is the aetiology of Gastroenteritis and Infectious Colitis?
Can be caused by viruses, bacteria, protozoa or toxins contained in contaminated food or water
What are the common causative organisms of Gastroenteritis and Infectious Colitis?
Viral: Rotavirus, adenovirus, astrovirus
Bacterial: Campylobacter jejuni, Escherichia coli, Salmonella, Shigella, Vibrio cholerae, Listeria, Yersinia enterocolitica
Protozoal: Entamoeba histolytica
Toxins: From Staphylococcus aureus, Clostridium botulinum, Bacillus cereus, mushrooms, heavy metals, seafood
Commonly contaminated foods: Improperly cooked meat (S. aureus, C. perfringens), old rice (B. cereus, S. aureus), eggs and poultry (Salmonella), milk and cheeses (Listeria,
Campylobacter), canned food (botulism)
What is the epidemiology of Gastroenteritis and Infectious Colitis?
Common, and often under-reported, a serious cause of morbidity and mortality in the developing world
What are the presenting symptoms of Gastroenteritis and Infectious Colitis?
Sudden onset nausea, vomiting, anorexia
Diarrhoea (bloody or watery)
Abdominal pain or discomfort
Fever and malaise
*Enquire about recent travel, antibiotic use and recent food intake (how cooked, source andwhether anyone else ill)
Time of onset:
-Toxins (early; 1–24 h)
-Bacterial/viral/protozoal (12 h or later)
Effect of toxin:
-Botulinum causes paralysis
-Mushrooms can cause fits, renal or liver failure
What are the signs of Gastroenteritis and Infectious Colitis on physical examination?
Diffuse abdominal tenderness Abdominal distension Bowel sounds are often increased If severe: -Pyrexia -Dehydration -Hypotension -Peripheral shutdown
What are the appropriate investigations for Gastroenteritis and Infectious Colitis?
Blood:
-FBC
-Blood culture (helps identification if bacteriaemia present)
-U&Es: dehydration
Stool:
-Faecal microscopy for polymorphs, parasites, oocysts, culture, electron microscopy (used to diagnose viral infections)
-Analysis for toxins, particularly for pseudomembranous
colitis (Clostridium difficile toxin)
AXR or ultrasound:
-To exclude other causes of abdominal pain
Sigmoidoscopy:
-Often unnecessary unless inflammatory bowel disease needs to be excluded
What is the management for Gastroenteritis and Infectious Colitis?
Bed rest
Fluid and electrolyte replacement with oral rehydration solution (containing glucose and salt)
IV rehydration may be necessary in those with severe vomiting
*Most infections are self-limiting
-Antibiotic treatment is only warranted if severe or the infective agent has been identified (e.g. ciprofloxacin against Salmonella, Shigella, Campylobacter)
Botulism: Botulinum antitoxin IM and manage in ITU.
Public health:
-Often a notifiable disease
-Educate on basic hygiene and cooking
What are the complications of Gastroenteritis and Infectious Colitis?
Dehydration
Electrolyte imbalance
Pre-renal failure
Secondary lactose intolerance (particularly in infants)
Sepsis and shock (particularly Salmonella and Shigella)
Haemolytic uraemic syndrome is associated with toxins from E. coli
Guillian–Barre syndrome may occur weeks after recovery from Campylobacter gastroenteritis
*Botulism: Respiratory muscle weakness or paralysis
What is the prognosis for Gastroenteritis and Infectious Colitis?
Generally good, as the majority of cases are self-limiting
What is Herpes Simplex Virus?
Disease resulting from HSV1 or HSV2 infection
What is the aetiology of Herpes Simplex Virus?
HSV is an alpha-herpes virus with double-stranded deoxyribonucleic acid (dsDNA)
Transmitted via close contact with an individual shedding the virus (e.g. kissing, sexual intercourse)
What is the epidemiology of Herpes Simplex Virus?
90% adults seropositive for HSV1 by 30 years
35% adults >60 years seropositive for HSV2
Over 1/3 world population has recurrent HSV infections
Most common cause of encephalitis
What are the presenting symptoms of Herpes Simplex Virus?
HSV1:
Primary infection often asymptomatic
Usual symptoms:
-Pharyngitis;
-Gingivostomatis, may make eating very painful
-Herpetic whitlow, inoculation of virus into a finger
Recurrent infection/reactivation (herpes labialis/cold sore):
- Prodrome (6 h) peri-oral tingling and burning
- Vesicles appear (48 h duration), ulcerate and crust over -Complete healing 8–10 days
HSV2:
Very painful blisters and rash in genital, perigenital and anal area
Dysuria
Fever and malaise
What are the signs of Herpes Simplex Virus on physical examination?
HSV1:
Primary infection:
-Tender cervical lymphadenopathy
-Erythematous, oedematous pharynx
-Oral ulcers filled with yellow slough (gingivostomatitis)
-Digital blisters/pustules (herpetic whitlow)
Herpes labialis: Perioral vesicles/ulcers/crusting
HSV2:
- Maculopapular rash
- Vesicles and ulcers (external genitalia, anal margin, upper thighs)
- Inguinal lymphadenopathy
- Pyrexia
What are the appropriate investigations for Herpes Simplex Virus?
Usually a clinical diagnosis
Vesicle fluid: Electron microscopy, PCR, direct immunofluorescence, growth of virus in tissue culture
What is Human immunodeficiency virus (HIV)?
A pandemic infectious disease whose impact on societies is without precedent
It is caused by a retrovirus that infects and replicates in human lymphocytes and macrophages, eroding the integrity of the human immune system over a number of years
This results in immune deficiency and a susceptibility to a series of opportunistic and other infections as well as the development of certain malignancies
What is the aetiology of Human immunodeficiency virus (HIV)?
HIV is retrovirus that infects and replicates primarily in human CD4+ T cells and macrophages
It can be transmitted via blood, blood products, sexual fluids, other fluids containing blood, and breast milk
Most individuals are infected with HIV through:
- Sexual contact (most common)
- Before birth or during delivery
- During breastfeeding
- When sharing contaminated needles and syringes (intravenous drug users)
What is the epidemiology of Human immunodeficiency virus (HIV)?
Globally, the HIV incidence rate is believed to have peaked in the late 1990s and to have stabilised subsequently
Transmission among heterosexuals was the largest single route of infection
>40,000,000 adults affected worldwide
What are the presenting symptoms of Human immunodeficiency virus (HIV)?
Three phases:
1. Seroconversion: (4–8 weeks post-infection)
Self-limiting
Fever, night sweats
Generalized lymphadenopathy
Sore throat
Oral ulcers
Rash
Myalgia
Headache
Encephalitis
Diarrhoea
2. Early/asymptomatic: (18 months to 15 +years)
Apparently well -some patients may have persistent lymphadenopathy (>1 cm nodes, at 2 + extrainguinal sites for >3 months)
Progressive minor symptoms, e.g. rash, oral thrush, weight loss, malaise
3. AIDS: Syndrome of secondary diseases reflecting severe immuno deficiency or direct effect
of HIV infection (CD4 cell count <200/mm3)
What are the direct effects of HIV?
Neurological: Polyneuropathy, myelopathy, dementia Lung: Lymphocytic interstitial pneumonitis
Heart: Cardiomyopathy, myocarditis
Haematological: Anaemia, thrombocytopenia
GI: Anorexia, HIV enteropathy (malabsorption and diarrhoea), severe wasting
Eyes: Cotton wool spots
What are the secondary infections arising from HIV immunodeficiency?
Bacterial: Mycobacteria (lungs, GI, skin), e.g. Mycobacterium tuberculosis, staphylococci (skin), Salmonella, capsulated organisms (Streptococcus pneumoniae, Haemophilus influenzae)
Viral: CMV (retinitis, oesophagitis, colitis, pneumonitis, adrenalitis, encephalitis), HSV (encephalitis), varicella zoster virus (VZV) (recurrent shingles), human papillomavirus (HPV) (warts), Epstein–Barr virus (EBV)
Fungal: Pneumocystis pneumonia (PCP), Cryptococcus (meningitis), Candida (oral, airway, genital, oesophageal), invasive aspergillosis
Protozoal: Toxoplasmosis (cerebral abscess, chorioretinitis, encephalitis)
What are the tumours that arise from HIV immunodeficiency?
Kaposis sarcoma (cutaneous or conjunctival vascular tumour caused by human herpesvirus)
Squamous cell carcinoma (particularly cervical or anal)
Non- Hodgkins B-cell lymphoma (brain, GI)
Hodgkins lymphoma
What are the appropriate investigations for Human immunodeficiency virus (HIV)?
HIV testing (after discussion and consent):
-e.g. Serum HIV enzyme linked immunosorbent assay: positive/Serum HIV rapid test
-HIV antibodies (usually positive by 12 weeks after exposure)
-PCR for viral RNA or incorporated proviral DNA
Monitor CD4+ count and viral load
Others: (as appropriate)
-For PCP (Pneumocystis pneumonia):CXR bilateral perihilar/ground glass shadowing, bronchoalveolar lavage -Cryptococcal meningitis: Brain CT or MRI, lumbar puncture – cerebrospinal fluid (CSF) microscopy (India ink staining), culture, ELISA for antigen
CMV (colitis): Colonoscopy and biopsy (cytomegalic cells with inclusions)
Toxoplasmosis: Brain CT or MRI shows ring-enhancing lesions
Cryptosporidia/microsporidia: Stool microscopy
What is Incision and drainage of an abscess?
A treatment for abscesses to relieve pain and speed healing
What are the indications for Incision and drainage of an abscess?
The treatment typically used to clear an abscess of pus and start the healing process
Smaller abscesses may not need to be drained to disappear
What are the possible complications of Incision and drainage of an abscess?
Damage to adjacent structures
Bacteremic complications
Spread of infection owing to inadequate drainage (dissemination)
What is infectious mononucleosis?
A clinical syndrome most commonly caused by Epstein Barr virus (EBV) infection, also known as glandular fever
What is the aetiology of infectious mononucleosis?
Epstein Barr virus (EBV), also known as human herpes virus 4, is the aetiological agent in approximately 80% to 90% of cases
Other causes: Herpes virus 6, cytomegalovirus and HSV-1
What are the risk factors for infectious mononucleosis?
Close contact e.g. kissing, sharing eating utensils, sexual behaviour
What is the epidemiology of infectious mononucleosis?
Common (UK annual incidence 1 in 1000)
Has two peaks:
1. 1–6 years (usually asymptomatic)
2. 14–20 years
What are the presenting symptoms of infectious mononucleosis?
Incubation period: 4–8 weeks
May have abrupt onset: sore throat, fever, fatigue, headache, malaise, anorexia, sweating, abdominal pain
What are the signs of infectious mononucleosis on physical examination?
Pyrexia
Oedema and erythema of pharynx, fauces and soft palate, with white/creamy exudate on the tonsils which becomes confluent within 1–2 days, palatal petechiae. Cervical/generalized lymphadenopathy
Splenomegaly (50–60%), hepatomegaly (10–20%).
Jaundice (5–10%)
What are the appropriate investigations for infectious mononucleosis?
1st line:
- Bloods: FBC (leukocytosis), LFT (raised aminotransferases)
- Blood film: Lymphocytosis (>20% atypical lymphocytes)
- Heterophile antibodies: produced in response to EBV infection
- EBV specific antibodies
- Throat swab: exclude streptococcal tonsilitis
Consider: CT of abdomen (splenic rupture)
What is Infective Endocarditis?
Infection involving the endocardial surface of the heart, including the valvular structures, the chordae tendineae, sites of septal defects, or the mural endocardium
What is the aetiology of Infective Endocarditis?
The endocardium can be colonized by virtually any organism, but the most common are:
- Streptococci (40%): Mainly a-haemolytic
- Staphylococci(35%):Staphylococcusaureus
- Enterococci (20%)
Historical sources of bacteraemia should be considered, such as indwelling vascular catheters, recent dental work, and intravenous drug use
RF: prosthetic heart valves, congenial heart disease, valvular disease, IV drug use
What is the epidemiology of Infective Endocarditis?
Incidence 16–22 per million per year, around 50% are over 60 years old
Incidence increases with age
What are the presenting symptoms of Infective Endocarditis?
Fever with sweats/chills/rigors (may be relapsing and remitting) Malaise Fatigue Weight loss Headache Arthralgia Myalgia Dyspnoea Confusion (particularly in elderly) Skin lesions
What are the signs of Infective Endocarditis on physical examination?
Pyrexia, tachycardia, signs of anaemia
Clubbing (if long-standing)
New regurgitant murmur or muffled heart sounds:
Frequency: Mitral > aortic > tricuspid > pulmonary
Splenomegaly
Vasculitic lesions:
-Petechiae particularly on retinae (Roths spots)
-Pharyngeal and conjunctival mucosa
-Janeway lesions (painless palmar macules, which blanch on pressure)
-Oslers nodes (tender nodules on finger/toe pads)
-Splinter haemorrhages (nail-bed haemorrhages)
What are the appropriate investigations for Infective Endocarditis?
Bloods:
-FBC (leukocytosis, normocytic anaemia)
-Raised ESR and CRP
-U&Es: mildly elevated urea
-Rheumatoid factors: may be positive (minor criteria for diagnosis)
-Complement levels: decreased
Blood culture: At least three sets 1h apart: bacteraemia or fungaemia
ECG: progression of the infection may lead to conduction system disease
Imaging:
Echocardiography: Should be performed in all cases of suspected IE, detection of vegetations and valve abscess, diagnosis of prosthetic valve endocarditis and assessment of embolic risk
CT/CXR: valvular abnormalities and vegetations, septic pul- monary emboli: focal lung infiltrates
What is Dukes’ classification of Infective Endocarditis?
Major criteria:
Positive blood culture in two separate sample
-Positive echocardiogram (vegetation, abscess, prosthetic valve dehiscence, new valve regurgitation)
Minor criteria:
- High-grade pyrexia (temperature >38C)
- Risk factors (abnormal valves, IV drug use, dental surgery)
- Positive blood culture, but not major criteria
- Positive echocardiogram, but not major criteria
- Vascular signs
What is the management for Infective Endocarditis?
ABC approach
1. Broad-spectrum antimicrobial therapy is required empirically on clinical suspicion:
-Benzylpenicillin + gentamicin (empirical treatment)
2. Streptococci: Continue as above (alternatives – ceftriaxone, vancomycin)
3. Staphylococci: Flucloxacillin/vancomycin + gentamicin (for prosthetic valves: vancomycin + gentamicin + rifampin)
Enterococci: Ampicillin + gentamicin
Surgery: If poor response or deterioration, urgent valve replacement is indicated.
*Antibiotic prophylaxis for patients with a PMH of infective endocarditis undergoing high risk procedures
What are the complications of Infective Endocarditis?
Valve incompetence Intracardiac fistulae or abscesses Aneurysm formation Heart failure Renal failure Glomerulonephritis Arterial emboli from the vegetations (brain, kidneys, lungs, spleen)
What is the prognosis for Infective Endocarditis?
Fatal if untreated
Even when treated, 15–30% mortality (mortality is greater in older patients)
What is Malaria?
A parasitic infection caused by protozoa of the genus Plasmodium.
Five species are known to infect humans; Plasmodium falciparum is the most life-threatening
What is the aetiology of Malaria?
It is naturally transmitted to humans through a bite by an infected female Anopheles mosquito but may potentially be transmitted by blood transfusion or organ transplantation
What is the epidemiology of Malaria?
It is widely distributed throughout tropical and subtropical regions, and the main burden of disease falls on these areas (93% of all malaria deaths occurred in the African region)
Travellers account for the majority of disease in Western countries
*Pregnant women and children aged under 5 years remain the most susceptible to disease in endemic areas
What are the presenting symptoms of Malaria?
*High degree of clinical suspicion in any feverish traveller (incubation up to 1 year, but usually 1–2 weeks)
*Cyclical symptoms of high fever, flulike symptoms, severe sweating and shivering cold/rigors
Peak temperature may coincide with rupture of the intra-erythrocytic schizonts:
-every 48 h for P. falciprum (malignant tertian)
-every 72 h for P. malariae (benign quartan)
-every 48 h for P. vivax and P. ovale (benign tertian)
What are the signs of Malaria on physical examination?
Pyrexia/rigors
Anaemia
Hepatosplenomegaly
What are the appropriate investigations for Malaria?
Thick/thin blood film (using Fields or Giemsas stain):
- -Test of choice to identify parasite
- Detection of asexual or sexual forms of the parasites inside erythrocytes
- Measure daily for detection and quantitative count of level of intracellular ring forms.
- Has to be negative for 3 days to exclude malaria
- > 2% in P. falciparum malaria is severe
Rapid diagnostic test: immunochromatographic tests detect the presence of malaria antigen or enzyme and typically give a visible band after 15 minutes if positive
Bloods:
- FBC (anaemia, prothrombin time may be moderately prolonged)
- U&Es: usually normal or mildly impaired; renal failure may be present in severe infection
- LFTs: may show elevated bilirubin or elevated aminotransferases
- ABG: In severe malaria, tissue hypoxia due to microvascular obstruction, impaired red cell deformability, anaemia, hypovolaemia, and hypotension can lead to lactic acidosis, which may contribute to impaired level of consciousness
Urinalysis: In severe Plasmodium falciparum infections, massive haemolysis combined with acute tubular necrosis produce acute renal failure with haemoglobinuria and proteinuria
What is mastitis?
Inflammation of the breast with or without infection
What are breast abscesses?
A breast abscess is a localised area of infection with a walled-off collection of pus
It may or may not be associated with mastitis (as a complication)
What are the two types of mastitis with infection?
Lactational
Non-lactational
What is the aetiology for mastitis/ breast abscesses?
Infectious mastitis and breast abscesses are usually caused by bacteria colonising the skin. Cases due to Staphylococcus aureus are by far the most common.
Non-infectious mastitis may result from underlying duct ectasia and infrequently foreign material (e.g. nipple piercing, breast implant)
What is the epidemiology for mastitis/breast abscesses?
The global prevalence of mastitis in lactating women is approximately 1% to 10% but may be higher
Breast abscess develops in 3% to 11% of women with mastitis
What are the presenting symptoms for mastitis/breast abscesses?
Fever
Decreased milk outflow (if lactational)
Breast warmth/ tenderness/ swelling/ redness (erythema)
Flu like symptoms- malaise and myalgia
What are the signs of mastitis/breast abscesses on physical examination?
Breast erythema
UNCOMMON: Breast mass, fistula, nipple inversion/retraction, nipple discharge, lymphadenopathy, extra-mammary lesions
What are the appropriate investigations for mastitis/breast abscesses?
1st line:
-Breast ultrasound-hypoechoic lesion (abscess), may be well circumscribed, irregular, or ill defined
-Diagnostic needle aspiration- purulent fluid indicates a breast abscess
-CMS of nipple discharge or needle aspirate- indicate infection/malignancy
(CMS- cytology, microscopy and sensitivity)
Others: pregnancy test, mammogram, blood culture
What is the management for mastitis/breast abscesses?
The goal of treatment for mastitis is to provide prompt and appropriate management to prevent complications such as a breast abscess. Lactational: -Effective milk removal -Antibiotic therapy -Warm compresses -Symptomatic relief
Non-lactational:
- Antimicrobial therapy (observational period)
- Supportive measures should include analgesia, if necessary.
- For granulomatous mastitis (idiopathic granulomatous inflammation)- glucocorticosteroids
What are the complications of mastitis/breast abscesses?
Breast abscesses (less than 10% of patients with mastitis)
Cessation of breastfeeding (most patients can continue to breastfeed)
Sepsis
Scarring (recurrent infections)
Functional mastectomy (breast that is unable to effectively lactate as a complication of prior tissue destruction from infection or treatment)
What is the prognosis for mastitis/breast abscesses?
When treated promptly and appropriately, most breast infections, including abscess, will resolve without serious complications.
Resolution of mastitis after 2-3 days of appropriate antibiotic therapy is expected among most patients.
Lactational abscesses tend to be easier to treat than non-lactational abscesses- these are multi-factorial and have a greater risk of becoming chronic
What is Meningitis?
Inflammation of the meninges (pia mater and arachnoid) (coverings of the brain) most commonly caused by infection
What is the aetiology of Meningitis?
Infection:
Bacterial:
-Neonates: Group B streptococci, Escherichia coli, Listeria monocytogenes
-Children: Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae
-Adults: *Neisseria meningitidis (meningococcus), Streptococcus pneumoniae, TB
-Elderly: Streptococcus pneumoniae, Listeria monocytogenes
Viral: Enteroviruses, mumps, Herpes simplex V, HIV
Fungal: Cryptococcus (associated with HIV infection)
What are the risk factors for Meningitis?
Close communities (e.g. dormitories) Basal skull fractures Mastoiditis Sinusitis Inner ear infections Alcoholism Immunodeficiency Splenectomy Sickle cell anaemia CSF shunts Intracranial surgery
What is the epidemiology of Meningitis?
Variation according to geography, age, social conditions
Viral meningitis is one of the most common infections of the CNS
What are the presenting symptoms of Meningitis?
ASK ABOUT TRAVEL HISTORY *Severe headache *Photophobia *Neck stiffness or backache Irritability Drowsiness Vomiting Fever Clouding of consciousness High-pitched crying or fits (common in children)
What are the signs of Meningitis on physical examination?
Signs of meningism: -Photophobia -Neck stiffness Signs of infection: -Fever -Tachycardia -Hypotension -Skin rash (petechiae with meningococcal septicaemia) -Altered mental state
What are the appropriate investigations for Meningitis?
Blood: Two sets of blood cultures (do not delay antibiotics)
Imaging:
-CT scan to exclude a mass lesion or increased intracranial pressure before LP, (may lead to cerebral herniation during subsequent CSF removal)
*A CT scan of the head must be done before LP in patients with:
-Immunodeficiency
-History of CNS disease
-Reduced consciousness
-Fit
-Focal neurologic deficit
-Papilloedema
Lumbar puncture: Send CSF for MCS and Gram staining (Streptococcus pneumoniae: Gram-positive diplococcic, Neisseria Meningitidis: gram-negative diplococcic)
Bacterial: Cloudy CSF, raised neutrophils, raised protein, reduced glucose (CSF: serum glucose ratio of <0.5)
Viral: raised Lymphocytes, raised protein BUT normal glucose
*TB: Fibrinous CSF, raised lymphocytes, raised protein, reduced glucose
