Infectious Diseases Flashcards
You are the F1 in AMU and are phoned by a GP about a 23 year old lady with the a twelve hour
history with rapid onset of severe headache, vomiting, neck stiffness, photophobia and fever
She took paracetamol with no effect and the family are concerned as she is becoming drowsy. On
examination the GP reports a GCS of 13/15 and Mrs. Ill has a rash developing on her abdomen.
1. What is the likely diagnosis?
2. What is your immediate advice to the GP?
3. If the patient has a penicillin allergy what further advice would you give?
1 - Menigococcal septicaemia (Sepsis as has a rash)
2 - IM benPen 1.2g
-Send to A&E blue light
3 - meropenem IV (borad spec abx) 2g tds,
You are the F1 in AMU and are phoned by a GP about a 23 year old lady with the a twelve hour
history with rapid onset of severe headache, vomiting, neck stiffness, photophobia and fever
She took paracetamol with no effect and the family are concerned as she is becoming drowsy. On
examination the GP reports a GCS of 13/15 and Mrs. Ill has a rash developing on her abdomen.
On arrival the patient is localising to pain, is opening her eyes in response to speech and has
confused conversation. She is pyrexial at 38.7, HR is 98 and BP is 100/60. There is an obvious
rash on her abdomen, arms and legs.
4. What immediate investigations and treatment are necessary? Why are you doing these investigations?
5. Describe the rash you would expect to see?
6. What was the patient’s GCS on admission? If the patient had been alert and orientated on
admission, with a headache, fever and neck stiffness but no rash, what other investigation
would you do?
7. How can you determine if it is safe to do this procedure?
8. Which investigations should be performed on specimens collected during this procedure?
9. Describe the results you would expect from the procedure carried out in question 8 for A.
a viral cause and B. a bacterial cause?
10. Name two organisms likely to cause this disease in adults?
11. What is the treatment if the cause is viral?
12. Which institution needs to be informed of anyone diagnosed with a bacterial form of this
infection and what treatment may be advised for close contacts of the patient?
4- ABCDE, BUFALO
Ix - FBC (WCC, platelets / clotting (DIC), U+E (Pre-renal renal failure) / Lactate, LFT, ABG (Acidosis), Glucose (hypo common in sepsis)
- Peripheral blood for meningococcal / pneumococcal PCR
- throat swab for neisseria, blood cultures
- urinary culture - pneumococcal
IV dexamethasone before the first dose of IV Ceftriaxone 2g
5 - Non blanching purpuric
6 - 12. LP (delay it if you have signs of septicaemia - because you can get the result from blood if they have bacteraemia - don’t need to put them at risk of LP complications)
7 - MUST DO FUNDOSCOPY AND MAYBE CT Signs of ICP (Fundoscopy - Papilloedema, Cushing’s reflex (Bradycardia + hypertension), CT head
8 - Protein, glucose, PCR, culture and sensitivities, neutrophils (viral -> lymphocytes), lactate, gram stain, colour
9 - bacterial = turgid, low glucose, raise protein, neutrophils
viral = clear, normal glucose, slightly raised protein, lymphocytes
10 -
VIRUSES = HSV (high dose IV acyclovir 10mg/kg but think about kidneys before), enterovirus
BACTERIA = Strep. P, N. Meningitides, group B strep (babies)
11 - Supportive if purely meningitis, when it becomes encephalitis they need to treat it with acyclovir (VZV, HSV)
12 - Public health England - proper officer, Rifampicin or ciprofloxacin
A 24 year-old medical student presents with a febrile illness one day after returning from her
elective period in Kenya. She complains of fevers, headaches and myalgia. She was “fully
vaccinated” prior to her trip and took Chloroquine and Proguanil anti-malaria prophylaxis.
Medical examination is unremarkable except for a fever of 39.5
1. What is your differential diagnosis?
2. What investigations do you wish to perform?
3. The haematologists report she has Plasmodium falciparum with a parasitaemia of 3%.
- What action is required now? Prescribe any treatment on the drug chart.
- How would you monitor her response to treatment?
-Why is monitoring LFTs important? - What are the complications of severe malaria?
- What anti-malarial drugs can be used for a) prophylaxis b) treatment?
1- Malaria / dengue / hepatitis / meningitis
2- Blood + films,
FBC (Anaemia, thrombocytopenia, platelets - low in active malaria)
HIV test
Blood cultures
PCR for dengue, yellow fever, zika
CXR
Xray of liver and spleen
Thick = screening film so can if see the plasmodium species are there (sensitivity)
Thin = find the species (identification)
3- 2-5% is parasitaemia severe.
4- ABCDE, IV Artesunate
5- Obs (HR, BP, Temp, Urine)
- glucose (if on quinine), platelets, HB, LFTs (haemolysis in malaria can cause Increased bilirubin and pre-hepatic jaundice)
- daily blood films - parasite count
- IV monitoring
6- parasite >2%, hypoglycaemia (quinine rather than malaria), DIC, haematuria, renal impairment, ARDS, normocytic anaemia, liver dysfunction, cerebral malaria –> Reduced GCS + seizures.
7- Propylaxis - Cloraquine, doxycycline, Malarone
Treat - Artesunate, quinine, Malarone
It is your first day on call as a house officer in AMU and you are called to see Mr Smith, a 35
year old male who gives the following history;
Increasing SOB over 10/7
Fever, rigors, headache and myalgia for 7/7
Cough with dirty green sputum 7/7
Saw GP 2/7 ago, who gave a course of amoxicillin with no improvement
Patient returned from a holiday in Tenerife 10/7 ago where he stayed in a hotel
PMH Asthma since childhood
SH Lifelong smoker 15 pack years
O/E Pt appears unwell- SOB with minimal exertion
HR 110, BP 110/80, RR 30, SpO2 92% on air, Temp 38.5
Signs of left lower lobe consolidation
Labs WCC 12.2, Hb 13.1, Na 128, K 4.1, Urea 7.8, Creatinine 110, AST 84, ALT 66, Bil 12
[Think of this in terms of CAP as well]
- What is your most likely clinical diagnosis?
- What investigations would you like to do?
- Name 5 markers of clinical severity associated with an increased risk of death
- Which organism is the commonest cause of this disease? Which organism would you
suspect in this patient and why? - What are the potential complications of this disease?
- What is your management plan for this patient?
1- Community aquired pneumonia
- Leigonnaires disease (Holiday, timeline 10days, fever, headache, myalgia)
2- Antigen test for legionella in urine
->Sputum culture (to genotype it)
3- CURB65
-confusion, urea >7, RR>25, BP<90, >65
(She scores 3)
4- CAP - strep. pneumonia, h. Influenza, staph aureus
Atypical types - Chlamydia pneumonia, mycoplasma, legionella
Investigations - CXR, sputum culture
5- Respiratory failure, AKI, septic shock, encepalopathy, pericarditis, abscess, Pleural effusion / empyema (Differentiating these 2 important)
6- CAP +CURB65 >3 -> Amox and clarynthromycin until you know that it is legionella!
Legionella -> IV Chlarythromycin for severe disease or a quinolone
A 50-year-old man, who works as a fishmonger, presents with a 3-day history of diarrhoea and
vomiting. Diarrhoea approx. 10x per day no blood no mucous, vomiting approx every hour.
Ate “shellfish for starters followed by turkey” the day before he became unwell. Rest of family
all well. Patient has never travelled outside of Yorkshire.
On questioning, he reports feeling dizzy on standing, weak and thirsty.
PMH gastritis diagnosed approx 2 years – refused endoscopy, Type II diabetic
DH Lansoprazole, Metformin
SH Non-smoker, drinks “social amounts” alcohol, no pets
What in this Hx increases risk of gastroenteritis?
1. What is the differential diagnosis?
2. What organisms are likely pathogens in this case?
3. What investigations would you do?
4. Outline your treatment plan. Prescribe appropriate treatment on the drug chart. In
what circumstances would you give antibiotic therapy?
5. What are the Public Health issues relating to this case?
Lansoprazole - Alters pH -> increased risk gastroenteritis
1- Viral hepatitis
-campylobacter, salmonella, shigella, E. coli (0157, 0404)
Rotavirus, norovirus
3- 3x Stool MC+S + Norovirus PCR (can also do on vom), Hep A serology, U+E as dehydrated, LFT, Clotting (as ?hepatitis)
4- ABCDE
Fluid resus if needed
If severe = erythromycin for campylobacter
If severe = cipro for salmonella/shigella
5- notifiable, works in food handling - if you work in the food industry can’t go back to work for a week after the last vomit/shit
A 20-year-old plumber was admitted with a three day history of painful swelling of his left leg
and groin and feeling generally unwell with episodes of fever with rigors. He was a known
insulin-dependent diabetic and his diabetes was normally well controlled although his blood
sugar had been quite erratic over the last 48 hours.
On examination he had a temperature of 38oC, pulse was 108/min and his blood pressure
was120/80. He had a marked area of swelling and erythema over his left shin spreading towards
the ankle and knee. This area was warm and tender to touch. He also had tender lymph nodes,
which were palpable in his groin. There were no obvious breaks in the skin of his leg or his feet.
Investigations showed a WCC of 26x10 /l with a neutrophilia of 23x10/l. His blood sugar was
22mmol/l and his CRP was 259mg/l.
1. What is the diagnosis?
2. What predisposing factor has he to this type of infection?
3. What further investigations are needed?
4. What are the most likely pathogens?
5. How would you manage this patient? Prescribe any treatment on the drug chart.
6. What other potentially dangerous condition should be considered in your differential
diagnosis?
1 - Cellulitis
2- Diabetic
3- Swabs between the toes, blood cultures, Sepsis 6
-Temp, U+E, LFT, FBC
4- Staph aureus, Group A strep
5-ABCDE sepsis 6
IV Abx (as systemically unwell, diabetic, WCC 26)
Fluclox (staph) and BenPen (strep)
6- Necrotising fasciitis (diabetes + unwell + if BP drops)
-this until proven otherwise
A 24-year HIV positive man presents with a 12 day history of increasing shortness of breath and
a non-productive cough. He was diagnosed with HIV 3 years ago but had not been started on
anti-retroviral therapy because of his chaotic lifestyle and failure to attend clinics. His CD4
count on diagnosis was 300.
On examination, he is febrile, his oxygen saturations at rest on air are 87% falling to 72% with
exertion. Chest examination is unremarkable. A CXR reveals bilateral fine peri-hilar infiltrates
1. What is the most likely diagnosis in this case? why?
2. What do you think his CD4 count is now?
3. List another important HIV associated lung conditions?
4. 3 investigations would you do?
5. Prescribe the treatment for his lung condition ?
6. What prophylaxis is used to prevent which infections in HIV infected patients?
PCP (pneumocystitis pneumonia) Caused by Pneumocystis jiroveci - no treatment, dry cough (other pneumonias normally productive), reduced sats on exertion, cxr findings (bat wing)
2- probably decreased to below 200 as infection / no treatment. Don’t usually get PCP unless CD4 >200
3- AIDS defining - PCP, bacterial pneumonia (pneumococcal), TB
-Lung Ca, Pulm artery HTN, COPD, MAI
4- PaO2 to assess severity, ABG, LDH
- Viral load, CD4 count
- PCR of induced sputum for PCP (deep sputum)
- you would do a sputum culture to check for spree. pneumoniae
5-Co-trimoxazole IV for PCP +HIV treatment
6- Co-trimoxazole oral - PCP
Azithromycin - MAI if CD4<50
Isosanazid + rifimpamycin - TB
What is issue with co-trimoxazole
Bone marrow suppression
Nephrotoxic
Target CD4 / vial load in hiv
CD4 > 400 cells/mm3
Viral load - <40 (Want 0)
What does HIV do
destroys CD4 cells - these are T helper lymphocytes which carry CD4 on their surfaces
What is reverse transcription
viral RNA -> DNA
How does HIV enter cell?
through binding of viral envelope glycoprotein (GP120
What is meant by window period in HIV testing
Immediately post infection (2-3 weeks) no antibody response mounted therefore false negative
What Ix for Dx of HIV
Serum (or salivary) HIV ELISA
Western blot - expensive tho
serum p24 antigen - detectable <4weeks
What other Ix bar diagnosis in HIV
Serum cd4 and viral load - used as markers to assess advance of disease
Hep B /c
Tuberculin skin test - because TB is an AIDs defining condition
CXR - look for PCP, TB, COPD etc
Preg - vertical transmission
Can you disclose a positive HIV result to partner without consent ?
Yes
Can be criminally liable if know status and transmit infection
CD4 for AIDS
<200
What is being described here?
Short illness soon after infection - highest infectivity. Antibody becomes detectable in blood, antigen becomes undetectable
Fever lasting >4d
Aching limbs
Blotchy red rash
Headache
Diarrhoea
Mouth ulcers
Seroconversion / primary HIV
AIDS defining conditions?
PCP, CMV, TB, Oral hairy leukoplakia,
sentinel tumours - Kaposi’s sarcoma or lymphoma
Mx of CD4 <200
Prophylaxis is recommended until CD4 count increases under HAART to prevent opportunistic infections:
Co-trimoxazole - PCP, toxoplasmosis and bacterial infection. SE: rash and BM suppression
Azithromycin - used to protect against MAI in patients with a CD4 count of <50
Ganciclovir - treatment and secondary prophylaxis for active CMV disease
Isoniazid (6M) +/- rifampicin (3M) for LTB if +ve quantiferon
Name 2 mx of candidiasis
Clotrimazole - canestan
Fluconazole
Nystatin
Methods of preventing HIV …NAME 3
Circumcision
Microbicidal gel (with tenofovir)
Reduce vertical transmission
Post exposure prophylaxis
Screen blood products, needle exchange
Behavioural - appropriate sex-education, condoms
HAART = highly active anti-retroviral therapy
How many drugs do you use for MX of HIV ?
3
2 x NRTI + 1 x NNRTI
or 2 x NRTI + 1 x PI
What are NRTIs ? eg?
Nucleoside reverse transcriptase inhibitors
Lamivudine, zidovudine (AZT), tenofovir (TDF), emtricitabine (FTC)
What are NNRTI? EG?
Non-nucleoside reverse transcriptase inhibitors
Nevirapine
what are PIs? eg?
protease inhibitors
Lopinavir
Name 2 barriers to compliance of HIV meds
SE
Social support
Stigma of HIV
Ix in viral haemorrhagic fever?
FBC: leukopenia and thrombocytopenia
LFT: elevated transaminases
Coagulation screen: PTT, INR and clotting times prolonged
[DIC
PCR]
Mx of Viral haem fevers
Notify public health and proper officer (local communicable disease consultant)
Seek advice on prevention transmission
Barrier nursing and visitor restriction
Supportive management: blood volume, clotting, care of major organs
Antivirals (ribavirin) - no use for Ebola or Marburg
Cause of amoebiasis
Ingestion of cysts in faecally contaminated food and water
