infection SBAs Flashcards
Pyogenic liver abscesses (liver infection with walled off collection of pus fluid) are caused by pathogens such as…
E coli Klebsiella Enterococcus Strep Staph
60% due to biliary tract disease (gallstones, strictures, cysts)
Cellulitis may precede abscesses.
Presentation of general abscess
and specific liver abscess signs
Fever + sweats Malaise Nausea Anorexia Weight loss Fluid thrill or fluctuation (liver abscess - jaundice, hepatomegaly, RUQ pain)
Amoebic liver abscesses are caused by…
Entamoeba histolytica
Aspiration of fluid = thick necrotic cell fluid
Hydatid liver cyst is caused by
Tapeworm
High levels of eosinophils
Common in sheep-rearing countries
Tuberculosis in liver can lead to
abscess/cysts
- ask about foreign travel.
Risk factors for candidiasis
Diabetes mellitus
Central venous catheters
Drugs (broad-spec Abx, immunosuppressants, steroids)
Neutropenia (HIV, pregnancy, malignancy)
Cellulitis risk factors
Skin break
Poor hygiene
Poor vascularisation of tissue e.g. in diabetes mellitus
Cellulitis commonest organisms
Strep pyogenes Staph aureus (i.e. MRSA)
Periorbital cellulitis presentations
Painful swollen eyelids
Orbital cellulitis presentations
Painful or limited eye movements
Visual impairment
Proptosis
Test for RAPD, acuity, colour vision (i.e. optic nerve function)
Lesion cellulitis presentations
Erythematous
Warm tender
Oedema
Indistinct/poorly demarcated edges and margins
Abscess Rx
Antibiotics
Aspiration of pus
Incision and drainage
Complete excision
Cellulitis Rx
Medical: oral penicillins or tetracyclines in most community acquired
Surgical: decompression in orbital cellulitis
Abscess: aspirate, incise, drain, excise
HSV1 - primary infection is often asymptomatic. Usual symptoms include…
pharyngitis
gingiovostomatis (painful eating)
herpetic whitlow
recurrent infection/reactivation (cold sore)
HSV2 (genital herpes) signs and symptoms
Maculopapular rash Painful blisters, vesicles and ulcers In genital, perigenital and anal area Dysuria Fever, malaise Inguinal lymphadenopathy
HSV encephalitis is caused by…
HSV1
Presents with encephalitis signs i.e. meningism + seizures + confusion
HSV keratoconjunctivitis signs and symptoms
Epiphoria (watery eyes)
Photophobia
Dendritic ulcer (stain with 1% fluorescein)
HSV8
Kaposi’s sarcoma
HSV3
Varicella zoster virus
Giant multinuclear cells indicates
herpes simplex virus
3 phases of HIV
- seroconversion (4-8weeks post-infection)
- early/asymptomatic (18months to 15+ years)
- AIDS (syndrome of secondary diseases)
Seroconversion (self-limiting) phase of HIV symptoms
Fever Night sweats Generalised lymphadenopathy Sore throat Oral ulcers Rash Headache/encephalitis
Early/asymptomatic phase of HIV symptoms
Persistent lymphadenopathy
Progressive minor symptoms e.g. rash, oral thrush, wt loss, malaise
HIV signs in the eyes
cotton wool spots
Secondary infections due to HIV immunodeficiency
Bacterial - TB, salmonella, strep pneumoniae
Viral - CMV, VZV, HPV (warts), EBV (oral hairy leukoplakia on side of tongue)
Malignancies associated with HIV
Kaposi’s sarcoma (HHV8)
SCC (cervical or anal)
Non-hodgkin’s b-cell lymphoma
Hodgkin’s lymphoma
HIV investigations
HIV antibodies
PCR for viral RNA
CD4 count and viral load
CXR (ground glass appearance in pneumocystis jiroveci)
Brain CT/MRI (ring-enhancing lesions in toxoplamosis)
Infectious mononucleosis (primary EBV infection) blood test and blood film results will show
High WCC
Abnormal LFTs
Atypical lymphocytes and lymphocytosis
also do paul-bunnell monospot test and throat swab
Paul-Bunnell/Monospot test is used in…
EBV infection:
heterophile antibodies produced in response
Infectious mononucleosis Rx
Bed rest
Paracetamol or NSAIDs
Corticosteroids
No contact sports for 2 weeks due to increased risk of splenic rupture
Amoxicillin or ampicillin given to patient with infectious mononucleosis will induce
Widespread maculopapular rash
Infectious mononucleosis complications
Lethargy months post-infection Resp airway obstruction Haemolytic/aplastic anaemia Thrombocytopenia Splenomegaly CNS - GBS, encephalitis Malignancy - lymphoma
Cyclical symptoms of high fever, flu-like symptoms, fever, vomiting, diarrhoea, severe sweating and shivering cold/rigors
Travel 1-2weeks ago Hx
Malaria
P. faliprum (48hr)
P. malariae (72hr)
P. vivax and P. ovale (48hr fever)
N.b. they can have jaundice and a palpable liver
Malaria diagnostic test
Thick/thin blood film
using Field’s or Giemsa’s stain.
(n.b. QBC and ICT tests)
Chicken pox VZV signs and symptoms
Macular papular rash in a dermatomal distribution (face and trunk mostly)
Crops of vesicles with weeping and crusting
Skin excoriation
Prodromal malaise
Mild pyrexia
Shingles presentation
Post-stress period
Tingling/hyperasthesia in a dermatomal distribution
Followed by vesicular macular papular rash in same distribution
Chicken pox (primary VZV infection) Rx
Children - treat symptoms (calamine lotion, analgesia, antihistamines)
Adults - aciclovir if within 24hr of rash
Shingles (reactivation of VZV) Rx
Aciclovir if within 72hr of appearance of rash if elderly, immunocompromised or opthalmic involvement
± low-dose amitriptyline
analgesia e.g. paracetamol
Post-herpetic neuralgia and ocular disease are common complications in
Shingles (VZV reactivation)
A 20 year old girl presents with 1 week Hx of have fever, sore throat, weight loss, pyrexia/high fever, lymphadenopathy, inflamed tonsils, and palatal petechiae in the mouth. What is the most likely diagnosis?
Infectious mononucleosis
severe glandular fever will also have splenomegaly, severe faitgue, hepatitis, atypical meningitis, enceptalitis, GBS
Pneumocystitis pneumonia (yeast-like fungus) causes…
pneumonia in immunocompromised patients i.e. HIV. Cough is usually non-productive.
CXR = reticular interstitial shadowing infiltrates
CT = ground glass
Profuse diarrhoea due to vibrio cholerae Rx
IV fluids for rehydration
Commonest cause of travellers’ diarrhoea
E coli
Important cause of diarrhoea outbreaks in children
Rotavirus
Cytomegalovirus causes an opportunistic infection in immunocompromised hosts that may resemble…
infectious mononucleosis
Non-blanching petechial rash is specific to which bacterial meningitis pathogen
Neisseria meningitis
Cerebral abscess can result from local infection. How would you treat:
- strep and anaerobic infections
- staph infections (commoner)
- IV cefuroxime and metronidazole
2. IV cefuroxime and flucloxacillin
High Ca2+ High ACE Lymphadenopathy Erythema nodosum Lupus pernio BHL Discolouration of face
Sarcoidosis
Transbronchial biopsy of sarcoidosis shows
Non-caseating granulomas
A 22 year old man presented with a two week history of fever and drenching night sweats. He had experienced severe itching during this time. Examination was normal except for swollen supraclavicular lymph nodes. CXR showed a mediastinal mass. what is the diagnosis?
Lymphoma
mediastinal involvement is common.
LNs commonly involved are cervical ±supraclavicular
pruritis is found in ~10%
50% associated with EBV infection
Salmonella is what type bacteria
Gram -ve bacilli
Lumbar puncture: gram -ve diplococci
Neisseria meningititis
40 year old social worker, lived in India & the Far East for the last 2 years. He came back with an intermittent fever of 2 months duration. On examination the GP noted tenderness & swelling of the right hypochondrium. He was sent to the hospital where on ultrasound a liver abscess was found. What is the diagnosis?
Amoebiasis - amoebic abscess. Caused by E. histolytica 50% report weight loss Hepatic infection (jaundice) Travel Hx Diagnosis from stool culture detects Ag.
Amoebic liver abscess Rx
- Nitroimdazole
- Paromomycin
- Incision, drainage of abscess
Night sweats, fever, malaise, cough, haemoptysis and erythema nodosum are all suggestive of…
TB
TB accounts for >90% erythema nodosum
First line tests to order for TB
CXR and sputum cultures
A 2 month old child has had a fever and cough for 3 days. He is tachypnoeic with grunting and has nasal flaring. What is the likely diagnosis?
Pneumonia
Displaying signs of respiratory distress.
Most sensitive and specific test here will be CXR, which shows infiltrate, consolidation, effusions or cavitations
Rx: antibiotics (amoxicillin 1st choice in children).
A 3 year old has a high fever and sore throat for 2 days. This evening he had a generalised convulsion lasting 2 minutes. He is now drowsy but rousable with no localising signs. What is the likely diagnosis?
Septicaemia secondary to a throat infection caused by group A b-haemolytic streptococcus (Strep pyogenes)
Rapid Ag test and throat swab
Rx: antibiotics
Best investigation for presumed infectious diarrhoea
Stool culture
A 35 year old homosexual man with HIV presents to his GP having recently noticed painless purple skin plaques on his lower legs and some generalised rubbery lumps over his body. O/E: purple coloured mass on his hard palate. What is the diagnosis?
Kaposi sarcoma - a low-grade neoplasm caused HHV8. It is associated with HIV immunodeficiency. Oral KS affects hard palate, gums and dorsum of tongue. Cutaneous lesions are purple, painless and non-pruritic. Histopathology of these lesions show atypical spindle-shape cells.
A sexually active female presents having noticed pearly umbilicated papules on her thigh which feel smooth to the touch. They are itchy. O/E: local erythema around these lesions. What is the diagnosis?
Molluscum contagiosum
Adults with STIs
Lesions = umbilicated pearly and smooth papules
1/3 have local redness, swelling or pruritis symptoms
A 35 year old woman who loves birds presents with a 10 day history of a low grade fever and a recent 2 day cough which is non-productive. O/E: diffuse crackles and mild hepatomegaly which is tender on palpation. What is the diagnosis?
Chlamydia psittaci causes a community-acquired atypical pneumonia
Hepatomegaly can occur here with pain but is uncommon
Rx: tetracyclines
A 3 year old girl presents with a week Hx of abdominal pain and watery diarrhoea which became bloody after 8 hours. 3 days before, she consumed an undercooked burger. Investigations show mild anaemia and thrombocytopenia with blood smear = multiple schistocytes. Creatinine is raised. What is the diagnosis?
Haemolytic uraemic syndrome secondary to E.coli gastroenteritis infection
HUS = MAHA, thrombocytopenia, AKI
Schistocytes = thrombotic microangiopathy
Plasmodium falciparum malaria bacteria causes ‘blackwater fever’ as a complication. Definition….
Haemolysis which releases Hb into the bloodstream and urine - presence of haemoglobinuria (dark red/black urine). Can lead to renal failure
Herpes labialis
Perioral vesicles / ulcers / crusting
Plasmodium falciparum malaria presentations
Fever spikes (48hr) Anaemia, jaundice, hepatosplenomegaly, thrombocytopenia
NO RASH OR LYMPHADENOPATHY
A 36 year old man who has sex with men comes to the GP with ulceration, bleeding and discomfort around his anus. He is trying alternative therapies to treat his HIV. What infection is the likely diagnosis?
Human Papillomavirus
Spread through sexual contact and causes genital warts. Also some with bleeding, pain, change in bowel habit, pruritis ani, masses. Immunosuppression increases inflammation ± development of cancer (cervical and anal).
