Infection Flashcards
Abx in appendicetomy, resection, biliary surgery?
Single dose 30 mins before surgery:
- Tazocin 4.5mg IV
- Gentamicin 1.5mg/kg and metronidazole 500mg IV
- Co-amoxiclav 1.2g
Abx in oesophageal, gastric surgery?
- Tazocin 4.5mg IV
- Gentamicin 1.5mg/kg
- Co-amoxiclav 1.2g
Abx in vascular surgery?
- Tazocin 4.5mg IV
- Flucloxicillin 1-2g + gentamicin 1.5mg
Add metronidazole if risk of anaerobes
- Amputations, gangrene, diabetes
Abx in surgery at risk of MRSA?
For high risk patients add teicoplanin/vancomycin to normalregimens
Pathophysiology/aetiology of infectious mono?
- 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
Signs/symptoms of infectious mono?
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
Complications of EBV/infectious mono?
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
Investigations in infectious mono?
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
Management of infectious mono?
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
What is SIRS criteria? Definitions of sepsis?
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
Markers of end-organ dysfunction in sepsis?
- Lactate >2
- Acute Resp failure requiring NIV or IV
- AKI stage 2 or above
- Platelets <100
- INR >1.5
- Hypotension/shock
Definition and causes of HAP?
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
Treatment of HAP?
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.
Pathophysiology of C.diff? Common causes?
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
Risk factors for C.diff?
- Prolonged abx use
- Multiple abx course
- Increased age
- Co-morbiditiy
- Invasive GI procedure
- Presence of NG
- Long hospital stay
- Immunocompromised
Complications of C.diff?
Ileus, toxic megacolon, dehydration, electrolyte disturbance, sepsis, perforation, death
Investigations in C.diff?
Bloods
- FBC - raised WCC
- U+E - check kidney function
Diagnosis
- Stool sample for C.diff toxin
Management of C.diff?
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
Prevention of C.diff?
- 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)
Definition of pyrexia of unknown origin?
Pyrexia >3 weeks with no identified cause, after evaluation in hospital for >3 days or >3 OP appointments.
(Pyrexia = >38.3)
Investigations in pyrexia of unknown origin?
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
Differentials for pyrexia of unknown origin?
Infection/malignancy = 40%
- HIV
- Connective tissue disease, vasculitis, granulomatous disease
- Elderly: PMR and GCA
- Younger patients: adult onset Still’s disease
Situations in which empirical treatment is advocated in pyrexia of unknown origin?
- Meet criteria for culture negative endocarditis
- Suggestive of disseminated TB or other granulomatous infection
- Temporal arteritis (with vision loss) suspected
Spread, incubation period and types of influenza?
- 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
High risk groups for flu?
- Chronic disease
- Immunosuppression
- Very young, elderly
- Pregnant
- BMI >40
Investigations for flu?
- Viral PCR, rapid antigen testing
- Viral culture (throat, nose, naso-pharyngeal, sputum)
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.
Who should get flu vaccine?
- High risk patients
- Children >2 years
- Healthcare workers
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
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.
Complications of measles?
Common = bronchopneumonia, otitis media
Post-measles encephalitis = drowsiness, vomiting, headahce, convulsions
Subacute sclerosing pan encephalitis = slow progressive neurological degeneration
Death
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
Spread of mumps?
- Respiratory droplet spread
- Incubation = 14-21 days
Presentation of mumps?
Symptoms
- Fever, myalgia, headahce
Signs
- Tender swelling of salivary glands
- Parotid > submandibular
Complications of mumps?
- Meningoencephalitis
- Epididymo-orchitis if pubertal/post-pubertal –> subfertility
- Oophoritis
- Pancreatitis
- Deafness
Investigations and management of mumps?
Investigations
- Mumps specific IgM/IgA
Management
- Supportive therapy
Cause and spread of rubella?
AKA german measles
- Respiratory droplet spread
- Incubation 14-21 days
- RNA virus of togaviridae family
Presentation of rubella?
Lymphadenopathy
- Occipitral, cervical, post-auricular
Maculopapular rash
- H+N –> trunk and extremities over 3-5 days
Complications of rubella?
Childhood
- Neuritis and arthritis
Congenital
- 90% risk of foetal malformation in 1st trimester
- Congenital heart defects, learning difficulties, sensorineural deafness, cataracts
What is TORCH syndrome?
- Toxoplasmosis
- Other: syphilis, parvovirus, VSV
- Rubella
- CMV
- Herpes simplex
Features = hepatosplenomegaly, fever, lethargy, difficult feeding, anaemia, petechiae, purpura, jaundice
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)
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)
High risk groups for chicken pox?
- Pregnant Women
- Immunocompromised
- Systemic disease
- Patients on high dose steroids
- Neonates
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
Complications of chicken pox?
- Scarring
- Secondary bacterial infections: Necrotising fasciitis, toxic shock syndrome
- Encephalitis: Cerebellar signs with ataxia
- In pregnancy: fetal varicella syndrome
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
5 causes of infective gastroenteritis (without blood)?
- Norovirus
- Rotavirus
- Enterotoxigenic E.coli
- Clostridium Perfringens (A)
- Vibrio cholerae (cholera)
What is commonest cause of traveller’s diarrhoea?
Enterotoxigenic E.coli
Management of cholera
- Rapid dipstick and culture confirmation
- ORS with safe water - NG/IV if low intake
What are you looking for in the stool to diagnose norovirus?
Reverse transcriptase
Advice for travellers to avoid enterotoxigenic e.coli?
- Boil water
- Avoid ice/shellfish/salads
- Handwashing
5 causes of dysentery?
- Shigella
- E.coli 0157
- Campylobacter
- Salmonella
- Yersinia
Transmission of the dysentery organisms?
- Shigella - faecal-oral
- E.coli 0157 - raw beef
- Campylobacter - raw meat/poultry, contaminated H2O
- Salmonella - meat, eggs, poultry, milk
- Yersinia - uncooked pork
Complication of E.coli 0157?
HUS
- Anaemia (haemolytic)
- AKI (uraemia)
- Thrombocytopenia
Avoid abx with this bacteria as it increases risk of HUS
Investigations in dysentery?
Stool culture
PCR immunoassay (shiga toxin, etc)
What to avoid in dysentery?
Avoid antidiarrhoeals - risk of toxic dilatation
Abx in dysentery?
If septic/severe/immunosuppressed
- Cipro/azithro
Usually just supportive management
Cause and spread of whooping cough?
Bordatella pertussis (gram +ve)
- Droplet spread
- RFs = unvaccinated/immunocompromised
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
When does whooping cough stop being infectious?
3-4 weeks after paroxysms (household contacts)
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
In whom should you consider malaria?
Anyone with a fever who has previously visited an area with prevalence, regardless of prophylaxis
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)
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.
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.
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
What confers resistance to malaria?
- Sickle cell anaemia
- G6PD deficiency
- Thalassaemia
Lack of Duffy antigen on RBCs
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
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.
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.
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
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.
Febrile traveller differentials?
(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.
