Infection Flashcards
1
Q
Abx in appendicetomy, resection, biliary surgery?
A
Single dose 30 mins before surgery:
- Tazocin 4.5mg IV
- Gentamicin 1.5mg/kg and metronidazole 500mg IV
- Co-amoxiclav 1.2g
2
Q
Abx in oesophageal, gastric surgery?
A
- Tazocin 4.5mg IV
- Gentamicin 1.5mg/kg
- Co-amoxiclav 1.2g
3
Q
Abx in vascular surgery?
A
- Tazocin 4.5mg IV
- Flucloxicillin 1-2g + gentamicin 1.5mg
Add metronidazole if risk of anaerobes
- Amputations, gangrene, diabetes
4
Q
Abx in surgery at risk of MRSA?
A
For high risk patients add teicoplanin/vancomycin to normalregimens
5
Q
Pathophysiology/aetiology of infectious mono?
A
- Epstein-Barr Virus (human herpes virus 4)
- More commonly young adults, incubation 4-8 weeks.
- Virus targets B lymphocytes
- Lifelong latent infection
- Affects squamous epithelial cells of oropharynx
6
Q
Signs/symptoms of infectious mono?
A
Symptoms
- Usually asymptomatic infection in childhood
- Sore throat, fever, anorexia, fatigue, malaise
- Usually 2 week course, recurrence rare
Signs
- Lymphadenopathy (posterior triangle), palatal petichiae, hepatomegaly, splenomegaly, jaundice
7
Q
Complications of EBV/infectious mono?
A
Acute
- Splenic rupture, upper airway obstruction, anaemia, kidney disease, neurological (CN palsy, Guillain-Barré, meningitis)
Oncogenic
- Burkitts/Hodgkin’s lymphoma, B cell lymphoma if immunosuppressed, gastric/nasopharyngeal cancer
8
Q
Investigations in infectious mono?
A
Bloods
- Film - lymphocytosis, large irregular nuclei
- FBC - high lymphocytes
- LFTs - raised ALT
- Serology - IgM if acute, IgG if past infection
Monospot antibody test (present in 85% of infection) - false +ve = pregnancy, AI disease, blood cancers
9
Q
Management of infectious mono?
A
Supportive
- Don’t give amoxicillin –> rash
- Advice
- Avoid contact sports for 3 weeks due to risk of splenic rupture
- Avoid alcohol for duration
Usually self-limiting
10
Q
What is SIRS criteria? Definitions of sepsis?
A
SIRS
- HR >90
- RR >20 or PaCO2 <4.3
- Temp <36 or >38.3
- WCC <4 or >12
Sepsis = SIRS + evidence of infection
Severe sepsis = sepsis + organ failure
Septic shock = sepsis + hypotension despite adequate fluid resuscitation
11
Q
Markers of end-organ dysfunction in sepsis?
A
- Lactate >2
- Acute Resp failure requiring NIV or IV
- AKI stage 2 or above
- Platelets <100
- INR >1.5
- Hypotension/shock
12
Q
Definition and causes of HAP?
A
Infection with symptoms >48 hours after admission
Less than 4 days
- S.pneumonia, H.influenza, Moraxella catarrhalis
More than 4 days
- Gram -ve bacilli/anaerobes
- Pseudomonas - ITU/post srugery.
- Klebsiella - rare - elderly, diabetc, alcoholic - cavitation i n upper lobe.
- S.aureus
13
Q
Treatment of HAP?
A
Local guidelines
- Aminoglycoside (gent) IV + antipseudomonal penicillin IV
- or 3rd gen cephalosporin
Prevent by mobilisation of surgical patients and adequate pain relief to allow deep breathing and prevention of atelectasis.
14
Q
Pathophysiology of C.diff? Common causes?
A
Inhibition of C.diff overgrowth by other competing chronic flora lost due to antibiotic expsoure
Normal bacteria converts to a growth state, releases enterotoxins A and B –> colitis.
Spread by person to person contact or faecal oral route.
- Pencillins, clindamycin, 3rd gen cephalosporins
- IV higher risk than oral
15
Q
Risk factors for C.diff?
A
- Prolonged abx use
- Multiple abx course
- Increased age
- Co-morbiditiy
- Invasive GI procedure
- Presence of NG
- Long hospital stay
- Immunocompromised
16
Q
Complications of C.diff?
A
Ileus, toxic megacolon, dehydration, electrolyte disturbance, sepsis, perforation, death
17
Q
Investigations in C.diff?
A
Bloods
- FBC - raised WCC
- U+E - check kidney function
Diagnosis
- Stool sample for C.diff toxin
18
Q
Management of C.diff?
A
Conservative (SIGHT)
- Suspect
- Isolate within 2 hours
- Gloves and aprons
- Hasnd wash with soap
- Test immediately (stool sample)
Medical
- Mild/moderate = metronidazole PO
- Severe = vancomycin PO or fidaxomicin (expensive)
- Non-responders = high dose vanc and IV metronidzole
- Recurrent = vanc/fidaxomicin +/- faecal transplant
19
Q
Prevention of C.diff?
A
- No benefit in prophylactic antibiotics
- Strict handwashing and rapid isolation of patients with diarrhoea
- Responsible abx prescribing (minimal types, oral if possible, not prolonged course)
20
Q
Definition of pyrexia of unknown origin?
A
Pyrexia >3 weeks with no identified cause, after evaluation in hospital for >3 days or >3 OP appointments.
(Pyrexia = >38.3)
21
Q
Investigations in pyrexia of unknown origin?
A
Bloods
- FBC, U+E, LFT, CRP, ESR
- HIV test
- CK, ANA, ANCA, RF, malaria, TB
MC+S
- Blood cultures (multiple)
- Urine, stool, CSF, sputum (including acid fast bacilli)
Imaging
- CXR, abdo/pelvis USS, venous doppler
Other
- Viral serology: hepatitis, CMV, EBV, toxoplasmosis, brucellosis
- Temporal artery biopsy if suspect GCA
22
Q
Differentials for pyrexia of unknown origin?
A
Infection/malignancy = 40%
- HIV
- Connective tissue disease, vasculitis, granulomatous disease
- Elderly: PMR and GCA
- Younger patients: adult onset Still’s disease
23
Q
Situations in which empirical treatment is advocated in pyrexia of unknown origin?
A
- Meet criteria for culture negative endocarditis
- Suggestive of disseminated TB or other granulomatous infection
- Temporal arteritis (with vision loss) suspected
24
Q
Spread, incubation period and types of influenza?
A
- Spread via aerosol droplets and contact
- Incubation period = 1-4 days
- Infective from 1 day prior to 7 days after symptoms
- Three subtypes = A (H1N1 and H3N1), B and C
25
High risk groups for flu?
* Chronic disease
* Immunosuppression
* Very young, elderly
* Pregnant
* BMI \>40
26
Investigations for flu?
* Viral PCR, rapid antigen testing
* Viral culture (throat, nose, naso-pharyngeal, sputum)
27
Management of flu?
**_Uncomplicated_**
* High risk = antivirals and symptomatic relief
* Low risk = symptomatic relief only
**_Complicated_** (LRTI, exacerbation of underlying condition, hospital admission)
* Oseltamavir (tamiflu) - 5/7 course. Not harmful in pregnancy.
* Supportive therapy alongside.
28
Who should get flu vaccine?
* High risk patients
* Children \>2 years
* Healthcare workers
29
Cause and spread of measles?
* Cause = morbillivirus (highly contagious)
* Airborne via respiratory droplets
* Incubation = 10-12 days
* Infective from 4 days before until 4 days after rash
30
Presentation of mealses?
**_Rash_**
* Morbilliform - maculopapular blanching rash - face --\> trunk --\> limbs
* Fades after 3-4 days in order of appearance
**_Fever_**
* With at least 1 of 3 Cs - **cough, coryza, conjunctivitis**.
**_Prodrome_**
* 2-4 days with fever, cough, runny nose, mild conjunctivitis and diarrhoea.
**_Kolpik's spots_**
* Small red spots with blue/white speck in centre - buccal mucosa.
31
Complications of measles?
**Common** = bronchopneumonia, otitis media
**Post-measles encephalitis** = drowsiness, vomiting, headahce, convulsions
**Subacute sclerosing pan encephalitis** = slow progressive neurological degeneration
**Death**
32
Investigations and management of mealses?
**_Investigations_**
* Salivary swab or serum sample for measles specific IgM taken within 6 weeks of onset
**_Management_**
* Often self-limiting: paracetamol, ibuprofen and plenty of fluids
* MMR vaccine within 72hrs of exposure if not had it
* If immunocompromised/pregnant immunoglobulin within 5 days of exposure
33
Spread of mumps?
* Respiratory droplet spread
* Incubation = 14-21 days
34
Presentation of mumps?
**_Symptoms_**
* Fever, myalgia, headahce
**_Signs_**
* Tender swelling of salivary glands
* Parotid \> submandibular
35
Complications of mumps?
* Meningoencephalitis
* Epididymo-orchitis if pubertal/post-pubertal --\> subfertility
* Oophoritis
* Pancreatitis
* Deafness
36
Investigations and management of mumps?
**_Investigations_**
* Mumps specific IgM/IgA
**_Management_**
* Supportive therapy
37
Cause and spread of rubella?
AKA german measles
* Respiratory droplet spread
* Incubation 14-21 days
* RNA virus of togaviridae family
38
Presentation of rubella?
**_Lymphadenopathy_**
* Occipitral, cervical, post-auricular
**_Maculopapular rash_**
* H+N --\> trunk and extremities over 3-5 days
39
Complications of rubella?
**_Childhood_**
* Neuritis and arthritis
**_Congenital_**
* 90% risk of foetal malformation in 1st trimester
* Congenital heart defects, learning difficulties, sensorineural deafness, cataracts
40
What is TORCH syndrome?
* Toxoplasmosis
* Other: syphilis, parvovirus, VSV
* Rubella
* CMV
* Herpes simplex
**Features** = hepatosplenomegaly, fever, lethargy, difficult feeding, anaemia, petechiae, purpura, jaundice
41
Investigations and management of rubella?
**_Investigations_**
* Offer IgM/IgG testing
* Rubella PCR from oral fluid sample
**Management**
* Notifiable disease
* Usually self-limiting (5-7 days)
* Supportive therapy unless immunocompromise (specialist advice)
42
Cause and spread of chicken pox?
Varicella zoster virus
* Incubation period = 7-14 days
* Infectivity is from a few days before the onset of lesions until the crust falls off.
Reactivation of dormant virus -\> shingles (dermatomal)
43
High risk groups for chicken pox?
* **Pregnant Women**
* Immunocompromised
* Systemic disease
* Patients on high dose steroids
* Neonates
44
Presentation of chicken pox?
**_Symptoms_**
* Headache, malaise, abdominal pain
* Crops of vesicles over 3-5 days
* Lesions very itchy
**_Signs_**
* Pyrexia
* Rash - *papule* --\> *vesicle* --\> *pustule* --\> *crust*
* Excoriations from scratching
45
Complications of chicken pox?
* Scarring
* Secondary bacterial infections: Necrotising fasciitis, toxic shock syndrome
* Encephalitis: Cerebellar signs with ataxia
* In pregnancy: fetal varicella syndrome
46
Management of chicken pox?
**_Low Risk_**
* Fluids, minimise scratching, PCM for fever and pain relief
* Calamine lotion/antihistamines for scratching
* Avoid contact with high risk groups
**_High Risk_**
* Check for varicella antibodies
* If not immune --\> immunoglobulin (\<10 days post-exposure)
* Oral aciclovir if they present \<24 hours post-onset of rash
47
5 causes of infective gastroenteritis (without blood)?
1. Norovirus
2. Rotavirus
3. Enterotoxigenic E.coli
4. Clostridium Perfringens (A)
5. Vibrio cholerae (cholera)
48
What is commonest cause of traveller's diarrhoea?
Enterotoxigenic E.coli
49
Management of cholera
* Rapid dipstick and culture confirmation
* ORS with safe water - NG/IV if low intake
50
What are you looking for in the stool to diagnose norovirus?
Reverse transcriptase
51
Advice for travellers to avoid enterotoxigenic e.coli?
* Boil water
* Avoid ice/shellfish/salads
* Handwashing
52
5 causes of dysentery?
1. Shigella
2. E.coli 0157
3. Campylobacter
4. Salmonella
5. Yersinia
53
Transmission of the dysentery organisms?
1. Shigella - faecal-oral
2. E.coli 0157 - raw beef
3. Campylobacter - raw meat/poultry, contaminated H2O
4. Salmonella - meat, eggs, poultry, milk
5. Yersinia - uncooked pork
54
Complication of E.coli 0157?
**_HUS_**
* Anaemia (haemolytic)
* AKI (uraemia)
* Thrombocytopenia
Avoid abx with this bacteria as it increases risk of HUS
55
Investigations in dysentery?
Stool culture
PCR immunoassay (shiga toxin, etc)
56
What to avoid in dysentery?
Avoid antidiarrhoeals - risk of toxic dilatation
57
Abx in dysentery?
If septic/severe/immunosuppressed
* Cipro/azithro
Usually just supportive management
58
Cause and spread of whooping cough?
Bordatella pertussis (gram +ve)
* Droplet spread
* RFs = unvaccinated/immunocompromised
59
Presentation of whooping cough?
**_Catarrhal Period (1-2 weeks)_**
* Insidious onset, low grade pyrexia, cough, coryzal symptoms
**_Paroxysmal (1-6 weeks)_**
* Paroxysms of coughing - worse at night
* Inspiratory whoop at end of coughing
* Fever; vomiting after paroxysm
**_Convalescent_**
* Decreased intensity of cough, gradual recovery
60
When does whooping cough stop being infectious?
3-4 weeks after paroxysms (household contacts)
61
Management of whooping cough?
**_Investigations_**
* PCR nasal/throat swab
**_Management_**
* Macrolides (erythro, clarithro, azithro) - reduces infectivity
* Exclude from nursery/school for 3-5 days after commencing treatment
62
In whom should you consider malaria?
Anyone with a fever who has previously visited an area with prevalence, regardless of prophylaxis
63
Aetiology of malaria?
Transmission through bite by female anopheles mosquito - sub-saharan Africa has 90% of cases.
Malaria belt = tropical and subtropical areas.
***Plamodium Falciparum***
* Most prominent in africa, most deaths worldwide
**Others**
* Vivax (Asia, Americas, Africa, Middle East)
* Malariae (Africa, Americas, SE asia)
* Ovale (Africa)
* Knowlesi (SE asia)
64
Presentation of Malaria?
3 months after visiting area
**_Signs_**
* Fever
* Late - jaundice, confusion, seizures, splenomegaly
**_Symptoms_**
* Non-specific
* Fever, extreme fatigue, headache, malaise, myalgia, diarrhoea, cough
* Fevers
* Paroxysms - relate to rupture of RBCs and release of inflammatory cytokines.
* Variable for falciparium, every 2 days for vivax, ovale.
65
Complications of severe malaria?
**_Cerebral Malaria_**
* Low GCS, seizures, coma
**_Bilious Malaria_**
* Diarrhoea, jaundice, liver failure
**_Lungs, Kidneys Spleen_**
* AKI, spontaneous bleeding, pulmonary oedema/ARDS, acidosis
***Overall, a sepsis-like picture that can lead to death - complicated malaria.***
66
Why is falciparium the worst malaria?
* Because it causes cytoadherence (clumping of RBCs)
* Stops blood flow to spleen so spleen can't clear infected cells
* Also causes ischaemic damage
* Ischaemic damage + haemolytic anaemia = organ failure
67
What confers resistance to malaria?
* Sickle cell anaemia
* G6PD deficiency
* Thalassaemia
Lack of Duffy antigen on RBCs
68
Investigations in malaria?
**_Thick and Thin Blood Film_**
* Thick = view parasites in RBCs, Thin = identifies plasmoidum species
* \>5% RBCs affected --\> worse outcomes
* If negative film, repeat at 12 and then 24 hours - malaria unlikely with 3 negative smears.
**_Others_**
* FBC, U+E, LFTs, clotting, glucose
* Low plts, high LDH (haemolysis), normochromic normocytic anaemia
* ABG
* Urinalysis
69
Prevention of malaria?
**_Vector Control_**
* Reduction of breeding sites (stagnant water)
* Insecticidal nets
* Indoor residual spraying
**_Bite Prevention_**
* Mosquito repellent (50% DEET) - apply after sunscreen.
**_Chemoprophylaxis_**
* Kills sporozoites before they infect hepatocytes.
70
Management of active malaria infection?
**_Uncomplicated_**
* Artemisinin combination therapy (ACT) to clear parasites
* Atovaquone proguanil/Oral quinine sulphate if not available
**_Severe_**
* Urgent parenteral treatment
* Artesunate IV, then full dose ACT
* Quinine regime IV
* Manage in high dependency setting - monitor BMs, Hb, clotting, U+E, daily parasite levels.
71
Malaria chemoprophylaxis?
**_Chloroquine_**
* 1 week before, 4 weeks after.
* GI disturbance, headahce. CI in epilepsy.
**_Proguanil_**
* Diarrhoea, antifolate (care if possibly prego)
**_Mefloquine_**
* 2-3 weeks prior, 4 weeks after.
* Neuropsychiatric SEs, dizziness
**_Doxycycline_**
* 1-2 days prior, 4 weeks after
* Hepatic impairment, photosensitivity, teratogenic
72
Things to ask in febrile traveller history?
Exclude malaria and HIV in all travelers. Don't forget normal differentials for fever.
**_Geography of Travel_**
* Urban, rural
**_Symptoms_**
* Onset, duration
**_Activities_**
* Bites, diet, fresh water exposure (schisto, leptospirosis), sexual activity, dust exposure, game parks, farms, caves, unwell contacts.
73
Febrile traveller differentials?
## Footnote
(Undifferentiated, rash, jaundice, hepato/splenomegaly, GI symptoms, respiratory symptoms, CNS symptoms)
**Undifferentiated fever**: Malaria, amoebic liver abscess, chikungunya, dengue, enteric fever, leptospirosis, schistosomiasis
**Fever with rash**: Dengue, VHF, schistosomiasis
**Fever with jaundice**: leptospirosis, viral hepatitis, VHF, yellow fever
**Fever with hepato/splenomegaly**: malaria, amoebic liver abscess, brucellosis, leptospirosis, trypanosomiasis, leishmaniasis
**Fever with gastrointestinal symptoms**: E. coli, Campylobacter, Salmonella, Shigella
**Fever with respiratory symptoms**: influenza, Streptococci, H. influenzae, TB
**Fever with CNS symptoms**: malaria, meningococcal, Japanese encephalitis, rabies, African trypanosomiasis.
