Infectious diseases Flashcards
How is meningitis investigated?
- lumbar puncture if no signs of raised ICP (ZN stain, cytology, virology, glucose, protein, culture PCR)
- FBC, CRP, coag, culture, glucose, gases, U&E, lactate, meningococcal and pneumococcal PCR
- throat swabs
- sometimes a CT scan
How is meningitis without signs of shock, severe sepsis or signs suggesting brain shift managed?
- dexamethoasone 10mg IV
- ceftriaxone IV
- careful fluid restriction
- Follow SEPSIS6
What signs suggest raised ICP and so you should delay LP in meningitis?
- severe sepsis or rapidly evolving rash
- severe resp/ cardiac compromise
- focal neurological signs
- papillodema
- continuous or uncontrollable seizures
- GCS<13
List 5 potential complications of meningitis
septic shock, DIC, septic arthritis, haemolytic anaemia, pericardial effusion, subdural effusion, SIADH, seizures, hearing loss, cranial nerve dysfunction
How should suspected TB be investigated?
- CXR
- 3 sputum samples for MC&S and ZN stain (may need todo bronchial washing)
- biopsy and needle aspiration for non resp TB
- HIV, Hep B and C serology
- FBC, U&E, CRP, coag
- MRI for leptomeningeal involvement
How is TB screened for?
Mantoux test + interferon gamma test
How is active TB managed?
- 6 months isoniazid and rifampicin and 2 months of pyranzinamide and ethambutol
+ pyridoxine with the iso - check vision baseline with snellen chart
- Do LFTs and U&Es to check baseline before starting therapy
- neg pressure room and PPI
- notify public health
How is latent TB managed?
6 months isoniazid or 3 months rifampicin and isoniazid + pyridoxine
notify public health
Give at least 1 adverse effect for each TB drug?
R: hepatotoxic, GI upset, autoimmune reactions, orange urine
I: hepatotoxic, peripheral neuritis, psychotic changes and epilepsy
P: hepatotoxic, GI upset,
E: Optic neuritis, hyperuricemia, GI upset, colourblindness
All: allergic reactions
List 5 common/ important diseases which could cause fever in a returing traveller?
malaria, dengue, typhoid, amoeba, viral haemorrhagic fever,
How does malaria present?
- travel history to area of high humidity, rural location, cheap accom, outdoors at night roughly 2 weeks ago
- non specific symptoms: fever, chills, headaches, cough, myalgia, GI upset
- signs: hepatomegaly, jaundice, abdo tenderness
What are features of late/ severe malaria?
Impaired consciousness, SOB, bleeding, fits, hypovolaemia, hypoglycaemia, AKI, resp distress syndrome
What are the 3 causative organisms of malaria and what are their incubations?
Plasmodium falciparum: 7-14 days (most common in africa)
Plasmodium vivax: 12-17 days w/ relapses common due to dormant parasites in liver
Plasmodium ovale: 15-18 days, also relapsing
How should suspected malaria be investigated? (4)
- 3x thick and thin blood films with giemsa stain
- rapid antigen test
- FBC, U&E, LFT, G6PD activity (prior to giving primaquine), blood glucose, gases, clotting, lactate (if severe)
- head CT
- CXR
How is p. falciparum treated?
IV quinine initially (needs ECG monitoring) then oral quinine and doxy for 7 days when they can swallow.
Supportive treatment also
Artesunate may be used in fututre
How is p vivax and ovale malaria treated?
Cholorquine (3-4 days) and primaquine (14 days)
Supportive treatment also
How does dengue fever present?
- abrupt onset high fever, severe headache behind eyes, myalgia, N+V, abdo pain
- macropapular blanching trunchal rash
- signs of bleeding, organ failure, hypovolaemia in severe disease
What countries is dengue common in and how long is the incubation period?
africa/ thailand/ americas
4-10 day incubation
carried by day biting mosquito
How is dengue investigated?
- FBC (high PCV, low platelets, leukopenia), clotting studies (prolongs APTT and PT), U&Es, LFTs
- Serum IgM and IgG antibody detection by ELISA
- CXR if pleural effusion suspected
- blood cultures
- malaria films
How is dengue managed?
- All supportive:
- Fever control w/ paracetamol/ tepid sponge/ fans
- Iv fluid resus and fluid balance monitoring
- haemorrhage and shock require FFP, platelets and sometimes infusion
- severe dengue may need ITU
How does typhoid present? What is the relevance of their tongue?
Gradually increasing fever, malaise, headache, dry cough, abdo pain, diarrhoea, furred tongue with red edges and tip, bradycardia
What organism causes thyphoid, what is incubation period and how does it spread?
Salmonella typhi
Incubation period is 10-20 days for S typhi and 1-10 days for S paratyphi
Spreads through contaminated water and food
How is typhoid investigated?
- Blood cultures (gram neg bacillus)
- FBC, U&E, LFT
- blood films for malaria
How is typhoid managed? (4)
- IV ceftriaxone or azithromycin
- steroids in severe disease
- supportive
- side room, PPE, careful handwashing and faeces disposal
- surgery if bowl perforates
What organism causes amoeba and what country is it prevalent in?
entamoeba histolytica
south and central america, west africa, SE asia
How long is incubation period and how does amoeba present?
Incubation 7 days- 4 months
Usually presents as dysentery (severe diarrhoea with blood and mucus).
Liver amoebiasis presents later w/ pyrexia, sweating, RUQ pain and abdo tenderness, hepatomegaly, weight loss, cough
How do you diagnose amoeba?
History+Specific stool E. histolytica testing (culture, antigen testing or PCR- 4-6 samples may be needed before a positive result)
USS or CT looking for liver abscesses
What is uses to treat dysentery and liver amoeba?
both PO metronidazole
Give 3 causes of viral haemorrhagic fever (VHF)?
All subtypes of RNA virus eg ebola, zika, dengue, yellow fever, crimean congo etc
How does VHF present?
- incubation of 2-21 days
- flushing, conjunctival injection, fever, malaise, flu like illness, petechial haemorrhages
- later mucous membrane haemorrhage, hypovolaemia, hypotension, shock, circulatory collapse
How should VHF be investigated?
- clotting studies
- FBC: leukopenia and thrombocytopenia
- LFTs, U&Es, LFTs (raised)
- D Dimers often high
- antibody test to identify virus
How should VHF be managed?
- notify public health
- barrier nursing, side rooms, visitor restriction (v contagious)
- supportive management (keep FFP on standby)
- monitor and support major organs
- no specific management
Give 4 common bacterial causes of pyrexia with unknown origin
- TB where dissemination has occurred there may be no localising signs and normal CXR
- Endocarditis (can be culture negative)
- Abcesses can have no localising symptoms, but may be from previous surgery, trauma, perinephric abcesses can have normal urinalysis
- hepatobillary infections
- osteomyelitis (usually causes pain)
- discitis
Give 3 viral causes of pyrexia of unknown origin
- CMV
- EBV
- HIV
Can all cause prolonged febrile illness with no prominent organ manifestation esp in elderly
State 2 factors that predispose you to disseminate fungal infections
immunosurpression, broad spectrum abx, IV devices and paraenteral nutrition
Which cancers are most associated with pyrexia of unknown origin?
- lymphoma
- leukaemia
- renal cell carcinoma
- mets from breast, liver, colon, pancreas
Name 2 drugs which could cause a pyrexia
B lactam abx
procainamide
isoniazid
phenytoin
Which autoimmune diseases could cause pyrexia of unknown origin?
- RA
- crohns and sarcoidosis (granulomatoid diseases)
- vasculitis (GCA, PMR)
Give 2 non infective, non neoplastic, non autoimmune causes of pyrexia of unknown origin?
- hyperthyroidism
- peripheral pulmonary emboli
- thrombophlebitis
- kikuchis disease (necrotising lymphadenitis- self limiting)
What specific investigations could be done to investigate pyrexia of unknown origin?
- Labelled white cell scan
- blood, urine, sputum, stool, CSF cultures
- hybrid PET CT
- skin biopsies or rashes
- lymph node aspirations or biopsies
What are the 3 principles of antimicrobial stewardship? give an eg of each
- persuasive (education, consensus, opinion leaders)
- restrictive (formulary restriction, prior authorisation, automatic stop orders)
- structural (computerised records, rapid lab tests, quality monitoring, expert systems)
Define pyrexia of unknown origin
temp of >38 on multiple occasions for 3 weeks with no identified cause despite 1 week in patient investigations
How should suspected HIV be investigated?
- HIV test (antigen and antibody testing, positive a few weeks after infection and get results on same day)
- CD4 count
- HIV viral load (PCR)
- HIV resistance profile
- syphillis and hep abc serology
- routine bloods
- taxoplasma, measles, varicella and rubellla IgG
- TB cultures often
Name 4 conditions and infections associated with severe HIV infection?
- kaposi sarcome
- TB
- PCP (pneumocystis jiroveci pneumonia)
- taxoplasmosis
- CMV
- lymphoma
- herpes
- candida
- cryptococcal meningitis
How is HIV managed?
Nucleoside receptor transcriptase inhibitor x2 (tenofovir, lamivudine)
+
non NRTI
or
protease inhibitor
or
integrase inihbitor
or
CCR5 (entry) inhibitor
AND hep B, pneumococcal and flu vaccines AND co trimoxazole for PCP prophylaxis if your CD4 is <200 AND opthalmology assesment for CMV retinitis if your CD4 count is <50
Also education about condoms etc is important
What extra is needed to treat TB if there is pericardial, meningeal or spinal involvement?
Steroids- the start of the anti TB meds will cause bacteria death and inflammation which will be bad in these places
Describe the pathogenesis of TB
- inhaled infectious droplets
- engulfed by alveolar macrophages and primary ghon focus forms
- some may get taken around body and to lymph nodes where t mediated immunity will contain the infection
- 5% will progress to active primary disease soon after
- latent infection then heals or self cures or lays dormant until reactivation due to immunocompromise causing post primary TB
Describe the differences between active and latent TB
active- cxr abnormal, sputum samples positive, symptoms (cough, fever, weightloss, nightsweats), infectious, mantoux and IFN gamma positive
latent- mantoux and IFN gamma positive, cxr usually normal, sputum cultured negative, no symptoms, not infectious
How is meningitis with signs of raised ICP, severe sepsis or a rapidly evolving rash managed?
- critical care input
- secure airway
- bloods and culutres
- fluid resus
- dexamethasone and ceftriaxone IV
- neuro imaging when stable
- delay LP
- catheter
- blood gasses
- source isolation until ceftriaxone for 24 hrs
- notify microbio and public health
