Infectious Diseases Flashcards
Hep A is an RNA virus, how is it spread? What is the incubation period?
Faecal - Oral spread or by shellfish
Incubation period is 2-6 weeks
Name four risk factors for Hepatitis
Personal contact
IVDU
MSM
Health workers
Give 5 symptoms of Hepatitis A
Nausea Malaise Arthralgia Jaundice Pale Stools/Dark Urine
What investigations would you do for Hepatitis A, and what would they show?
Immunoglobulins (raised IgG for acute infection)
LFTs (ALT raised, potential damage to synthetic function)
USS to exclude other diagnoses
How is Hepatitis A managed?
Supportive Avoid alcohol Vaccine available (works for one year or twenty with booster)
Hep B is a DNA virus, how is it spread? What is it’s incubation period?
Spread by blood products, sexual contact or vertically
Incubation is 1-6 months
Give 6 symptoms of Hep B
Nausea Malaise Arthralgia Urticaria Jaundice RUQ Ache
Describe the following Hep B Serology: HbsAg, HbeAg, Antibodies to core antigen, Antibodies to surface antigen
HbsAg - present 1-6 months after exposure (if persists past 6 months then it is chronic)
HbeAg - present 1.5-3 months after exposure (implies high infectivity)
Antibodies to core antigen imply past infection
Antibodies to surface antigen imply vaccination
Describe the management of Hep B
Supportive
Immunise sexual contacts
Any signs of chronic liver inflammation - 48/52 of retrovirals such as Peginterferon Alfa-2a
State two complications of Hep B
Cirrhosis
Hepatocellular Carcinoma
Hep C is a RNA virus, how is it spread? What is its incubation period?
Spread is via IVDU, Blood Transfusions and Sexual
Incubation is 6-9 weeks
How would acute Hep C present?
Often asymptomatic, may just be jaundiced
How would chronic Hep C present?
Over 80% of cases are chronic
Malaise, Weakness, Anorexia
Name three possible investigations for Hep C
LFTs
PCR of the virus to confirm ongoing infectivity
If PCR +ve then do a liver biopsy to assess damage
Describe the management of Hep C
Stop alcohol/smoking
Start anti-virals
NO VACCINE AVAILABLE
What is Hep D?
A co - infection for Hep B (as it is an incomplete RNA virus)
How would you investigate Hep D?
You would test for Anti Hep B antibody, and then if that was positive, proceed to do the Anti Hep D antibody
How would you manage Hep D?
Peginterferon Alfa-2a has limited success so a liver transplant may be required
Describe three features of Hep E’s pathophysiology/epidemiology
RNA virus similar to Hep A
Common in Indochina
Associated with pigs
Describe the pathophysiology of Meningitis
Inflammation of the leptomeninges (arachnoid and pia) by virus/bacteria/non infective causes
Give four risk factors for Meningitis
Young Age
Immunosupression
Crowding
Spinal Procedures
Name the causative organisms of bacterial meningitis in neonates
Group B Strep
E.Coli
Name the causative organisms of bacterial meningitis in adults
Haemophilus Influenza
Strep Pneumoniae
Neisseria Meningitidis
Name the causative organisms of bacterial meningitis in the elderly
Strep Pneumoniae
What is Aseptic Meningitis? Give 4 examples
When no bacteria can be cultured
Viral Infections, Fungal Infections, TB, Partially treated meningitis
Give 4 causes of non infective Meningitis
Malignant Cells (Leukaemias, Lymphomas)
Medication (NSAIDs, Trimethoprim)
Sarcoidosis
SLE
Give 5 symptoms of Meningitis
Fever Nausea Headache Nuchal Rigidity Photophobia
What are some differentials for Meningitis?
Intracranial Abscess
SAH
Encephalitis
What investigations should be performed if Meningitis is suspected?
Immediate Lumbar Puncture (pre abx) FBC, CRP Blood Culture ABG Coagulation Screen EEG (if seizing)
Describe the management of viral Meningitis
Supportive
IV Aciclovir if Herpes Simplex Virus is suspected
Describe the management of bacterial Meningitis
Supportive
IV Ceftriaxone AND Dexamethasone
Give 3 complications of Meningitis
Cerebral Oedema
SIADH
Waterhouse Friderichson Syndrome
What is Cellulitis?
Infection of the dermis and deep subcutaneous tissue with poorly demarcated borders
Likely due to Streptococcus Pyogenes or Staphylococcus Aureus
Give 4 risk factors for Cellulitis
Previous Cellulitis
Venous Insufficiency
Alcoholism
IVDU
How would Cellulitis present?
Usually unilateral and in lower limb
May have an area of damaged skin
Localised Erythema/Pain/Swelling
May have systemic symptoms
State 4 investigations you could do for suspected Cellulitis
Skin Swab
CRP
Fine Needle Aspirate
Culture
Give 3 features of a Cellulitis Management plan
Supportive (Rest, Elevation, Analgesia)
Flucloxacillin 500mg QTS (or Erythromycin if pen allergic)
Emollient to keep skin hydrated
Describe the pathophysiology of Malaria
Parasite infection from Plasmodium species of Mosquito (female only)
Most common is Falciparum followed by Vivax and Ovale
Sporozoites travel to the liver and become Merozoites
Give 4 clinical presentations of Malaria
High Fevers
Malaise
Headache
Myalgia
Name 2 signs OE of Malaria
Jaundice
Hepatosplenomegaly
Give three diagnostic techniques for Malaria
Microscopy
Rapid Diagnostic Test of Parasite Antigen
LFTS
How would you treat Malaria (P.Vivax and P.Ovale)?
Chloroquine
Primaquine (prevention of relapse - test for G6PDH first)
How would you treat Malaria (P.Falciparum)?
Oral Quinine Sulphate and Doxycycline
Give 3 risk factors for Gastroenteritis
Poor Personal Hygiene
Immunocompromised
Achlorhydria
What are the incubation periods of different Gastroenteritis infectants?
Viral - a day
Bacteria - Few hours to 4 days
Parasites - 7-10 days
Diagnosis of Gastroenteritis is normally clinical, but what investigations could you do?
Stool - Microscopy, Culture and Staining
Blood Tests
Imaging (if bowel distension)
What is the management of Gastroenteritis?
Supportive
Anti- Motility if required (eg Loperamide)
What is Osteomyelitis?
Infection of the bone marrow which can affect the cortex and periosteum (necrosis) via spread through Haversian Canals.
What are the most common pathogens causing Osteomyelitis?
Staphylococcus Aureus (most common)
Haemophilus Influenza
Escherichia Coli
Give four risk factors for Osteomyelitis
Trauma, Diabetes, IVDU, Peripheral Arterial Disease
How would Osteomyelitis of a long bone present?
Acutely febrile, Painful immobile limb
How would Osteomyelitis of vertebrae present?
Back pain worse at rest
Localised Oedema
Localised tenderness
What is Potts Disease? How would it present?
Osteomyelitis of the vertebrae, specifically as a result of TB
Causes vertebral body collapse, and abscess formation
What investigations would you do for suspected Osteomyelitis? What would they show?
FBC - Elevated white cells and inflammatory markers
Blood culture/bone culture
MRI - Bone marrow oedema
How would you manage acute osteomyelitis?
Extensive surgical cleaning
Flucloxacillin for 4-6 weeks
How would you manage chronic osteomyelitis?
Extensive surgical cleaning
Antibiotics for 3-6 months
Describe the pathophysiology of Infective Endocarditis in 3 steps
1) Turbulent flow damages endothelium
2) Platelets and fibrin adhere to give non bacterial thrombotic endocarditis
3) Circulating bacteria adhere to vegetation on the valves
What are the common causative organisms of Infective Endocarditis
Usually Strep Viridans
Staph Aureus in IVDU
May be fungal in immunocompromised/IVDU
Give three risk factors for Infective Endocarditis
Skin Breaches
Immunocompromised
Valvular Disease
Give 3 symptoms of Infective Endocarditis
Fevers
Rigors
Night Sweats
Give 3 signs of Infective Endocarditis
Splinter Haemorrhages
Janeway Lesions
New/Modified Cardiac Murmurs (usually Aortic Regurg)
A common complication of Infective Endocarditis is the formation of an Aortic Root Abscess, how would this present?
Prolonged PR Interval
AV block
Left Ventricular Failure
What investigations would you do for suspected Infective Endocarditis?
Trans-Oesophageal Echocardiography
Blood Cultures
ECG
CXR
How would you manage Infective Endocardtis?
Initial empirical treatment with Amoxicillin and Gentamicin while awaiting sensitivity results
Surgery indicated if heart failure or valvular obstruction
How is Typhoid fever transmitted? What is it’s incubation period?
Transmission is faecal-oral
Incubation is 6-30 days
Give 4 symptoms of Typhoid Fever
Fever
Malaise
Anorexia
Dry cough
Give 3 signs characteristic of Typhoid Fever
Faget’s Sign (Bradycardia and Fever)
Rose Spots
Hepatosplenomegaly
Give 3 investigations for Typhoid Fever
FBC
Blood Culture
Stool Culture
How would you manage Typhoid Fever?
Avoid Abx until diagnosis is confirmed
Azithromycine (1g PO on the first day, then 500mg daily after)
Define Pyrexia of Unknown Origin
Temperature more than 38 degrees on more than one occasion
Illness>3 weeks duration
No diagnosis despite 1 weeks worth of inpatient
Categories of causes of PUO include Infective/Autoimmune/Neoplastic and Other. Give 2 examples of each.
Infective - TB, Brucellosis (slow growing)
Autoimmune - Temporal Arteritis, Wegener’s Granulomatosis
Neoplastic - Leukaemia, Lymphoma
Other - Thromboembolism, Hyperthyroidism
What percentage of the population does C.Diff harmlessly colonate?
2-5%
What investigations would you do for C.Diff?
Stool tests (PCR for C.Diff proteins, ELISA for C.Diff toxins)
How would you manage mild and severe C.Diff respectively?
Stop causative antibiotic if possible
Mild - 400mg Metronidazole every 8 hours
Severe - 500mg Vancomycin every 6 hours (ideally PR due to better enteral penetration)
Give two complications of C.Diff
Toxic Megacolon (requiring urgent colectomy) Multi System Organ Failure
What is MRSA resistant to?
Beta Lactams
What percentage of the population is nasally colonised with MRSA?
20-30%
What investigation is carried out for suspected MRSA?
PCR for mecA gene
What is the management of an MRSA skin/soft tissue infection?
Incision and drainage
Tetracycline + Rifampicin OR Clindamycin
What is the management of a resp MRSA infection?
Tetracycline or Clindamycin
What is conjunctival suffusion? What is it caused by?
Reddening of the conjunctiva
Leptospirosis
Give 5 causes of splenomegaly
Malaria Leishmaniasis Typhoid Brucellosis EBV
Describe the pathophysiology of HIV in four steps
1) HIV binds to CD4 receptors on T cells
2) HIV uses reverse transcriptase to bind to host DNA
3) DNA replication
4) Causes inflammation and spreads to other tissues
How is HIV transmitted
Via bodily fluids
Give 5 symptoms of primary HIV
Flu like Maculopapular Rash Myalgia Lymphadenopathy Weight Loss
Describe the 5 stages of HIV in terms of CD4
Primary - Normal CD4 Stage 1 - >500 CD4 Stage 2 - <500 CD4 Stage 3 - <350 CD4 Stage 4 - <200 CD4 (AIDs Defining)
Give 3 investigations for HIV
ELISA for HIV antigen and antibody
Rapid Immuno- Assay Kit
Nucleic Acid Testing (for viral RNA)
State 5 Opportunistic diseases seen in HIV
PCP Pneumonia Candidiasis Cryptococcus Neoformans causing Meningitis Kaposi's Sarcoma Lymphoma
Name the four targets of HIV anti retrovirals
Inhibiting viral entry Inhibiting reverse transcriptase Inhibiting viral integration Inhibiting protease (viral maturation)
How is TB spread?
Aerosol inhalation causing pulmonary infection and subsequent haematogenous spread
What is the Quantiferon test?
Assesses the amount of interferon gamma released from T cells when exposed to mycobacterium
CANNOT differentiate between active and latent
What is the T Spot test?
Same principle as Quantiferon test but tests an individual T lymphocyte (good for immunosupressed patients)
How is latent TB treated?
Not treated if over 35 usually (high risk of hepatotoxicity)
3 months Rifampicin and Isoniazid OR 6 months Isoniazis
Give 4 symptoms of active TB
Non resolving cough
Weight loss
Night sweats
Haemoptysis
Describe 3 features seen on a TB XRay
Mediastinal lymphadenopathy
Cavitating Pneumonia
Pleural Effusion
What would be seen on a CT scan of TB?
Lymphadenopathy (often with central necrosis)
How would you aim to take a biopsy from a suspected pulmonary TB patient?
FIrst try a sputum sample
If the sputum sample is negative then proceed to bronchoscopy/EBUS to take sample from pulmonary lymph nodes (caseating granulomatous inflammation)
What would you see on the lumbar puncture of meningeal TB?
Inreased lymphocytes
HIGH protein
Low glucose
What is the paradoxical reaction in TB?
As bacteria die there is an increase in inflammation causing worsening symptoms
Steroids are initiated if this is in a place where an increase in inflammation would not be tolerable (eg CNS)
Describe the treatment plan for Active TB
2 months of Rifampicin/Isoniazid/Pyrazinamide/Ethabutol along with Pyridoxine
4 months of Rifampicin/Isoniazid plus Pyridoxine
Name 2 side effects of Rifampicin
Orange Urine
Drug induced hepatitis
Name 3 side effects of Isoniazid
Peripheral Neuropathy (vit B deficiency)
Colour Blindness
Drug induced hepatitis
Name a side effect of Pyrazinamide
Drug induced hepatitis
Name a side effect of Ethambutol
Reduced visual acuity
Give three features of infection control in TB
Contact tracing
Nursed in a side room until they’ve had atleast two weeks of treatment
Wear a mask if giving aerosol treatment such as nebuliser
What subtypes of Human Herpes Viruses are involved in Herpes Simplex Virus?
Human Herpes 1 & 2
Describe the pathophysiology of Herpes Simplex Virus
Viruses multiply in epithelial cells on skins surface producing vesicles/ulcers
Can enter sensory neurones and remain latent
Describe how primary Herpes Simplex VIrus would present
May have a prodrome of tingling along the sensory nerve
Vesicles/Shallows ulcers (healing in 8-12d)
Fever
Malaise
Lymphadenopathy
How would reactivation of Herpes Simplex Virus present?
Usually less severe than primary infection
What is Gingivostomatitis? How would it present?
Herpes infection of oral mucosa and gums
Fever, Sore throat, Tender oropharyngeal vesicles
How is active Herpes Simplex Virus treated?
Aciclovir (IV route if encephalitis)
How is VZV (HHV 3) transmitted? What is its incubation period?
Respiratory droplet infection
14-21d
Describe the pathophysiology of VZV
Infects respiratory mucosa
Multiplies in lymph nodes
Disseminates via mononuclear cells to skin epithelia
Can lay dormant in root of sensory nerve
How might chickenpox present?
May have a prodrome of fever/malaise/headache
Pruritic rash with vesicles that crust in 48h
What is the infectious period of chickenpox?
Infectious 1-2 days before lesions appear, and 5d after lesions have scabbed over
How would Shingles present?
Painful hyperaesthetic area
Vesicular rash in dermatomal region
Name two complications of Shingles
Post Herpetetic Neuralgia
Ramsey Hunt Syndrome
You only investigate VZV if the patient is immunocompromsied, what technique would you use?
Viral PCR
VZV is only treated in adults, how would you manage it?
Adults - Oral Aciclovir/Valaciclovir within 48h of rash
Immunocompromised/Pregnant - IV Aciclovir
What is a VZV vaccination?
Vaccination against Shingles given to over 70s
Describe the pathophysiology of EBV (HHV4)
Virus targetting circulating B lymphocytes and squamous epithelia of oropharynx
There are two ways in which EBV can present, describe them
Asymptomatic (normally in childhood)
Infectious Mononucleosis
What are the signs/symptoms of Infectious Mononucleosis?
Sore Throat Fever Anorexia Lymphadenopathy (especially in post.triangle) Hepatosplenomegaly Jaundice
What would a blood film of EBV show?
Lymphocytosis
Apart from a blood film, what other diagnostic tests could you do for EBV?
Viral PCR
Monospot (Heterophile antibodies produced by immune cells when exposed to EBV)
Name 4 cancers associated with EBV
Burkitts Lymphoma
Hodgekin’s Lymphoma
B Cell Lymphoma
Gastric Cancer
How do immunocompetent people infected with CMV (HHV5) present?
Often asymptomatic
May present as hepatitis
May present like Infectious Mononucleosis
How would immunocompromised people present with CMV?
Pneumonia - Fever, SOB
Who is at risk of congenital CMV?
When mothers do not have pre-existing immunity
How would congenital CMV present?
May appear healthy in utero
Sensorineural hearing loss
Mental Retardation
Cerebral Palsy
What situation puts patients at risk of CMV?
Organ Transplant (can even occur if patient is seropositive due to different strains)
Only immunodeficient and congenital patients are treated for CMV, what are they treated with?
Ganciclovir
How can CMV be prevented in transplantation?
both seronegative - leukodepleted blood and products
recipient serongeative - prophylaxis with Ganciclovir
What are the symptoms of Neisseria Gonorrhoea infections in men and women respectively?
Men - Urethral discharge/Dysuria
Women - Discharge/Dysuria/Lower abdo pain/Altered menstrual bleeding
How would you investigate suspected Gonorrhoea?
NAAT on first catch urine (men) or endocervical swab (women)
How would you manage Gonorrhoea pharmacologically?
500mg Ceftriaxone IM
1g Azithromycin PO
Give two complications of Gonorrhoea each for men and women
Men - Prostatitis, Epididymitis
Women - Salpingitis, Ectopic Pregnancy
How would Chlamydia present in a woman?
Dysparenuria
Dysuria
Post Coital Bleeding
Increased Discharge
What is an atypical presentation of Chlamydia?
Reiter’s Syndrome (Urethritis, Arthritis, Conjunctivitis)
How is Chlamydia managed pharmacologically?
100mg Doxycycline BD for one week
Name four ways Syphilis can be transmitted
Sexual contact with infectious lesions
Vertical transmission in utero
Blood transfusions
Break in skin
How does primary syphilis present?
Develops at site of infection less than 3 months after
Progresses from macule - papule - chancre
Enlarged regional lymph nodes
What is a chancre?
Painless ulcer with central sloughing and rolled edges
How does secondary syphilis present?
Occurs roughly 6 weeks after primary infection
Night time headaches
Malaise
Slight fever
Polymorphic rash affecting palms, soles of feet and face
Name the three categories of tertiary syphilis
Neurological (may be asymptomatic or may have sensory ataxia, dementia etc)
Cardiovascular (Aortitis)
Gummata (Inflammatory nodules/plaques in any organ which may be locally destructive)
How can you investigate Syphilis?
Treponemal Enzyme Immunoassay for IgM (early) or IgG
How would you treat Primary, Secondary and early latent Syphilis?
Benzathine Penacillin 2.4 mega units IM
How would you treat late latent Syphilis?
Benzathine Penicillin weekly for 3 weeks
Name two complications of Syphilis or its treatment
Miscarriage/Stillbirth
Jarisch Herxheimer Reaction (to treatment, febrile, headache, myalgia, chills)
What strains of HPV cause genital warts?
HPV6 and HPV11
How might Genital Warts present?
Painless lesions that may cause itching/bleeding/dysparenuria
How would you educate a patient with Genital Warts?
The virus has a long latent period
Recurrence of warts does not mean reinfection with virus/infidelity
Condom use until lesions have resolved
How would you treat Genital Warts?
May choose no treatment, will regress spontaneously in 6m
Non Keratinised - Podophyllotoxin cream
Keratinised - Imiquimod Cream
What is Trichomonas Vaginalis
A protozoal infection spread almost exclusively by sexual intercourse
What is ‘Strawberry Cervix’
Cervicitis caused by Trichomonas Vaginalis causing a strawberry appearance
How is Bacterial Vaginosis caused?
When Gardnerella Vaginalis outgrow the lactobacilli which normal inhabit the vagina, increasing the pH
Name 3 protective factors of Bacterial Vaginosis
COCP
Condom Use
Circumcised Partner
How is Bacterial Vaginosis managed?
Oral Metronidazole 400-500mg BD for 5-7 days
What is Schistosomiasis?
Fluke infection transmitted by contaminated water
How would acute Schistosomiasis present?
Swimmer's Rash Katayama Syndrome (Fever, Urticaria, Diarrhoea)
How would chronic Schistosomiasis present?
Intestinal Disease (pain,bloody stools) Urogenital Disease (Dysuria, CKD, Bladder Cancer) Lung Disease (Pulmonary Htn)
How is Schistosomiasis diagnosed?
Ova in urine/faeces
Abdo Xray - Bladder Calcification
USS - Hydronephrosis and thickened bladder wall
How is Schistosomiasis treated?
Praziquental
Steroids for Katayama Fever
Describe the pathophysiology of Tetanus
Caused by anaeobic Clostrodium Tetani spores in soil
Enters small wounds and produces neurotoxin (Tetanospasmin)
Neurotoxin disseminates via blood and lymphatics causing unopposed muscle contraction and spasm
Incubation of 3d to 3w
How would generalised Tetanus present?
Prodrome (fever,malaise,headache) Trismus (lock jaw) Neck Stiffness Swallowing Difficulties Muscular Spasms
How is Tetanus managed?
In ITU
IV Tetanus IG
Metronidazole
Benzodiazepines for spasms
Describe two screening methods for Latent TB
Mantoux
IGRA (Quantiferon or T Spot)
What do the results of the Mantoux test mean?
Negative: <6mm induration
Positive: >6mm induration
Strongly Positive: >15mm induration