Infectious Diseases Flashcards
Mycoplasma pneumoniae features?
- Prolonged and gradual onset
- Flu like symptoms precede a dry cough
- Bilateral consolidation on XR
- Often affects younger pts, epidemics every 4 years
- Atypical –> lacks peptidoglycan cell wall –> may not respond to penicillins or cephalosporins
Mycoplasma complications?
- Cold Agglutins (IgM) –> haemolytic anaemia, thrombocytopenia
- Erythema multiforme, erythema nodosum
- Heart = peri/myocarditis
- GI = hepatitis, pancreatitis
- Renal = acute glomerulonephritis
- Neuro = Meningoencephalitis, GBS
Mycoplasma Dx?
- Serology
- Positive cold agglutination test
Mycoplasma Rx?
Doxycycline or macrolide
Is HIV a notifiable disease?
No
Sepsis definition?
Life-threatening organ dysfunction caused by a dysregulated host response to infection
Septic shock definition?
A more severe form sepsis, technically defined as ‘in which circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone’
qSOFA score?
Adult patients outside of ICU with suspected infection are identified as being at heightened risk of mortality if score >=2 of:
1. RR > 22/min
2. SBP < 100
3. Altered mentation
Sepsis 6?
- IVF
- IV Abx
- O2
- UO
- Lactate
- Cultures
Giardiasis risk factors?
- Foreign travel
- Swimming/drinking water from river or lake
- Male-male sexual contact
Giardiasis features?
- Non-bloody diarrhoea = steatorrhoea
- Bloating, abdominal pain
- Lethargy, weight loss
- Flatulence
- Malabsorption and lactose intolerance can occur
Giardiasis Ix?
- Stool microscopy for trophozoite and cysts: sensitivity of around 65%
- Stool antigen detection assay: greater sensitivity and faster turn-around time than conventional stool microscopy methods
- PCR assays being developed
Giardiasis Rx?
Metronidazole
Parvovirus B19 infection causes?
- Erythema infectiosum
- Fifth disease
- Slapped cheek syndrome
Parvovirus exposure in early pregnancy?
If before 20 weeks, she should seek prompt advice from whoever is giving her antenatal care as maternal IgM and IgG will need to be checked.
Parvovirus B19 presentation?
- Slapped cheek in children
- Pancytopenia in immunosuppressed
- Aplastic crises in SCD
- Hydrops fetalis
Necrotising fasciitis causative organism
- Type 1 = Most common, mixed anaerobes and aerobes (often occurs post-surgery in diabetics)
- Type 2 = S. pyogenes
Necrotising fasciitis RFs?
- Skin factors = trauma, burns, soft tissue infections
- DM esp. SGLT2
- IVDU
- Immunosuppression
Necrotising fasciitis most common site?
Perineum (Fournier’s gangrene)
Necrotising fasciitis features?
- Acute onset
- Worsening cellulitis with pain out of keeping with physical features
- Extremely tender over infected tissue with hypoaesthesia to light touch
- Skin necrosis and crepitus/gas gangrene are late signs
- Fever and tachycardia may be absent or occur late in the presentation
Necrotising fasciitis Rx?
- Urgent surgical debridement
- IV Abx
Necrotising fasciitis prognosis?
Average mortality 20%
Cellulitis organisms?
S. aureus or S. pyogenes
Cellulitis diagnosis?
Clinical, no further Ix required in primary care
Cellulitis admission criteria classification system?
Eron classification (I-IV)
1. Ok and no comorbidities
2. Well/unwell and 1 comorbidity
3. Very unwell or limb threatening
4. Sepsis or Necrotising fasciitis
What cellulitis pts should be admitted for IV Abx?
- Eron Class III/IV
- Has severe or rapidly deteriorating cellulitis (for example extensive areas of skin)
- Is very young (under 1 year of age) or frail
- Immunocompromised
- Significant lymphoedema
- Facial cellulitis (unless very mild) or periorbital cellulitis
Cellulitis Rx?
- Flucloxacillin 1st line
- Clarithromycin/doxycycline/erythromycin (pregnancy) if pen allergic
- Severe –> Co-amoxiclav/cefuroxime/clindamycin/ceftriaxone
Traveller’s diarrhoea definition?
At least 3 loose to watery stools in 24 hours with or without one of more of abdominal cramps, fever, nausea, vomiting or blood in the stool. The most common cause is Escherichia coli.
Acute food poisoning definition?
Sudden onset of nausea, vomiting and diarrhoea after the ingestion of a toxin. Typically caused by Staphylococcus aureus, Bacillus cereus or Clostridium perfringens
E.coli diarrhoea history?
Traveller, watery stool, abdominal cramps and nausea
Giardia diarrhoea history?
Prolonged, non-bloody diarrhoea
Cholera diarrhoea history?
- Profuse, watery diarrhoea
- Severe dehydration resulting in weight loss
- Not common amongst travellers
Shigella diarrhoea history?
Bloody diarrhoea, vomiting, abdominal pain
S. aureus diarrhoea history?
Severe vomiting, short incubation period
Campylobacter diarrhoea history?
- Flu-like prodrome –> crampy abdominal pain, fever, diarrhoea
- May mimic appendicitis
- Complications incl. GBS
Bacillus cereus diarrhoea history?
- Vomiting within 6 hours stereotypically due to rice
- Diarrhoeal illness occurring after 6 hours
Amoebiasis diarrhoea history?
Gradual onset bloody diarrhoea, abdominal pain and tenderness which may last for several weeks
Diarrhoea 1-6 hour incubation period?
S. aures, B. cereus
Diarrhoea 12-48 hours incubation period?
Salmonella, E. coli
Diarrhoea 48-72 hours incubation period?
Shigella, campylobacter
Diarrhoea >7 day incubation period?
Giardia, Amoeba
Genital wart aka?
Condylomata accuminata
HPV types causing genital warts?
6 and 11
HPV types predisposing to cervical cancer?
16, 18, 33
Genital wart features?
- Small 2-5mm fleshy protuberances which are slightly pigmented
- May bleed or itch
Genital wart management?
- Topical podophyllum/cryotherapy 1st line
a. Multiple, non-keratinised warts –> topical podophyllum
b. Solitary, keratinised warts –> cryotherapy - Imiquimod 2nd line
Most common organism from animal bite?
Pasteurella multocida
Animal bite Rx?
- Cleanse wound. Don’t suture puncture wound unless cosmesis is at risk
- Co-amoxiclav
- If pen allergic then doxycycline + metronidazole
Human bite Rx?
Co-amoxiclav
Exacerbation of chronic bronchitis Rx?
Amoxicillin or tetracycline or clarithromycin
Uncomplicated CAP Rx?
Amoxicillin (Doxycycline or clarithromycin in penicillin allergic, add flucloxacillin if staphylococci suspected e.g. In influenza)
Possible atypical pneumonia Rx?
Clarithromycin
HAP Rx?
- Within 5d = Co-amoxiclav or cefuroxime
- > 5d = Tazocin or Quinolone (ciprofloxacin) or Broad-Spectrum Cephalosporin (Ceftazidime)
UTI Rx?
- Trimethoprim or nitrofurantoin
- Alternative = Amoxicillin or cephalosporin
Acute pyelonephritis Rx?
Broad-spectrum cephalosporin or quinolone
Acute prostatitis Rx?
Quinolone or trimethoprim
Impetigo Rx?
- Topical hydrogen peroxide
- Oral flucloxacillin or erythromycin if widespread
Cellulitis Rx?
Flucloxacillin
Cellulitis near eyes or nose Rx?
Co-amoxiclav
Erysipelas Rx?
Flucloxacillin
Mastitis during breast feeding Rx?
Flucloxacillin
Throat infection Rx?
- Phenoxymethylpenicillin
- Erythromycin alone if penicillin-allergic
Sinusitis Rx?
Phenoxymethylpenicillin
Otitis media Rx?
Amoxicillin (erythromycin if penicillin-allergic)
Otitis externa Rx?
Flucloxacillin (erythromycin if penicillin-allergic)
Periapical or periodontal abscess Rx?
Amoxicillin
Gingivitis: acute necrotising ulcerative Rx?
Metronidazole
Gonorrhoea Rx?
IM Ceftriaxone
Chlamydia Rx?
Doxycyline or Azithromycin
PID Rx?
- Oral ofloxacin + Oral metronidazole OR
- IM Ceftriaxone + Oral Doxycycline + Oral metronidazole
Syphilis Rx?
Benzathine benzylpenicillin or doxycycline or erythromycin
Bacterial Vaginosis Rx?
Oral/topical metronidazole or topical clindamycin
C. diff Rx?
- 1st episode = oral vancomycin
- 2nd episode = Oral fidoxamicin
Campylobacter enteritis Rx?
Clarithromycin
Salmonella (non-typhoid) Rx?
Ciprofloxacin
Shigella Rx?
Ciprofloxacin
Gonorrhoea features?
- Male = urethral discharge, dysuria
- Female = cervicitis e.g. leading to vaginal discharge
- Rectal and pharyngeal infection usually asymptomatic
Gonorrhoea local complications?
- Urethral strictures and epididymitis
- Salpingitis –> may lead to infertility
Gonorrhoea systemic complications?
- DGI = Disseminated gonococcal infection
- Gonococcal arthritis
Tenosynovitis, migratory polyarthritis and dermatitis (lesions can be maculopapular or vesicular)?
Disseminated gonococcal infection
Aspergilloma definition?
A mycetoma (mass-like fungus ball) which often colonises an existing lung cavity (e.g. secondary to tuberculosis, lung cancer or cystic fibrosis).
Aspergilloma features?
Cough and haemoptysis
Aspergilloma Ix?
- CXR containing a rounded opacity, crescent sign may be present
- High titres of Aspergillus precipitins
Spinal epidural abscess definition?
A collection of pus that is superficial to the dura mater (of the meninges) that covers the spinal cord
Spinal epidural abscess most common organism?
S. Aureus
Spinal epidural abscess pathophysiology?
- Contiguous spread = discitis
- Haematogenous spread = IVDU
- Direct infection = spinal surgery
Spinal epidural abscess presentation?
- Fever
- Back pain
- Focal neurological deficit
Spinal epidural abscess Ix?
- Bloods = incl. HIV, Hep B, Hep C
- Blood cultures
- MRI whole spine (since skip lesions may be present)
Lyme disease cause?
Borrelia burgdorferi
Lyme disease feature classification?
- Early (within 30 days) = erythema migrans, systemic features
- Late (after 30 days) = cardio, neuro
Lyme disease early features?
- Erythema migrans = bulls eye rash, 1-4 weeks after bite, painless, >5cm in diameter and slowly increases in size, present in 80% pts
- Systemic features = headache, lethargy, fever, arthralgia
Lyme disease later features?
- Cardio = heart block, peri/myocarditis
- Neuro = facial nerve palsy, radicular pain, meningitis
Lyme disease Ix?
- Clinically if erythema migrans is present –> Abx can be started
- 1st line = ELISA to borrelia burgdorferi = if negative and Lyme disease is still suspected in people tested within 4 weeks from symptom onset, repeat the ELISA 4-6 weeks after the first ELISA test. If still suspected in people who have had symptoms for 12 weeks or more then an immunoblot test should be done, if positive or equivocal then an immunoblot test for Lyme disease should be done
Rx of asymptomatic tick bites?
Remove tick with fine tipped tweezers, wash area, routine Abx not recommended
Suspected/confirmed Lyme disease Rx?
- Doxycycline if early disease (amoxicillin in pregnancy)
- Ceftriaxone if disseminated disease
- Jarisch-Herxheimer reaction is sometimes seen after initiating therapy: fever, rash, tachycardia after first dose of antibiotic (more commonly seen in syphilis, another spirochaetal disease
URTI symptoms + amoxicillin –> rash?
Likely glandular fever
Glandular fever causes?
EBV, CMV, HHV6
Glandular fever presentation?
- Sore throat
- Pyrexia
- Lymphadenopathy
Glandular fever features?
- Malaise, anorexia, headache
- Palatal petehiae
- Splenomegaly (50%)
- Hepatitis, transient rise in ALT
- Lymphocytosis = presence of 50% lymphocytes and at least 10% atypical lymphocytes
- Haemolytic anaemia secondary to cold agglutins (IgM)
- A maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis
Glandular fever Dx?
Heterophil antibody test (Monospot test) - NICE guidelines suggest FBC and Monospot in the 2nd week of the illness to confirm a diagnosis of glandular fever.
Glandular fever Rx?
- Supportive, avoid alcohol
- Avoid contact spots for 4 weeks to reduce risk of splenic rupture
Leptospirosis aetiology?
The spirochaete Leptospira interrogans (serogroup L. icterohaemorrhagiae), classically being spread by contact with infected rat urine.
Leptospirosis epidemiology?
- Sewage workers, farmers, vets, abattoir
- Returning traveller
Weil’s disease?
Hepatorenal failure associated with Leptospirosis
Leptospirosis features?
- Early = fever, flu-like symptoms, subconjunctival haemorrhage
- Late = AKI, Hepatitis, aseptic meningitis
Leptospirosis Ix?
- Serology = Abs to leptospira develop after about 7 days
- PCR
- Culture = may take several weeks so limits usefulness in Dx, blood and CSF samples are generally positive for the first 10 days, urine cultures become positive during the second week of illness
Leptospirosis Rx?
High dose benzylpenicillin or doxycycline
Differentiating erysipelas from other skin infections?
Lack of involvement of subcutaneous tissue
Main cause of erysipelas?
Streptococcus pyogenes, a beta-haemolytic group A streptococci and the rash is caused by an endotoxin rather than the bacteria itself
Most common STI in UK?
Chlamydia, around 1 in 10 young women have it
Chlamydia features?
Asymptomatic in 70% women and 50% men
1. Women = cervicitis (discharge, bleeding), dysuria
2. Men = urethral discharge, dysuria
Chlamydia Ix?
NAAT = vulvovaginal swab in women, urine test in men (should be carried out 2 weeks after a possible exposure)
Chlamydia screening?
Open to all 15-24 years
Chlamydia Rx?
- Doxycycline 7d 1st line
- If doxy C/I then Azithromycin 1g OD one day then 500mg OD two days
- If pregnancy = azithromycin/erythromycin/amoxicillin
Chlamydia contact tracing?
- Men with urethral symptoms = all contact since, and in the four weeks prior to, the onset of symptoms
- Women and asymptomatic men = all partners from the last six months or the most recent sexual partner should be contacted
- Contacts should have treat then test
When is test of cure for chlamydia in pregnant women?
6 weeks post infection
Is Test of Cure required in uncomplicated chlamydia infection in men and non- pregnant women?
No
Clue cells?
Bacterial vaginosis
BV definition?
Describes an overgrowth of predominately anaerobic organisms such as Gardnerella vaginalis. This leads to a consequent fall in lactic acid producing aerobic lactobacilli resulting in a raised vaginal pH.
BV features?
- Vaginal discharge = fishy, offensive
- Asymptomatic in 50%
Amsel’s criteria for BV?
3 out of 4 should be present
1. Thin, white homogeneous discharge
2. Clue cells on microscopy: stippled vaginal epithelial cells
3. Vaginal pH > 4.5
4. Positive whiff test (addition of KOH results in fish odour)
BV Rx?
- Oral metronidazole 5-7 days
- 70-80% initial cure rate
- Relapse rate > 50% within 3m
- Topical metronidazole/topical clindamycin are alternatives
Strawberry cervix?
Trichomonas vaginalis
BV in pregnancy mushkies?
- Results in an increased risk of preterm labour, low birth weight and chorioamnionitis, late miscarriage
- Treat with oral metronidazole as normal
Hep B needlestick transmission risk?
20-30%
Hep C needlestick transmission risk?
0.5-2%
HIV needlestick transmission risk?
0.3%
Hepatitis A PEP?
Human Normal Immunoglobulin (HNIG) or hepatitis A vaccine may be used depending on the clinical situation
Hepatitis B PEP HBsAg positive source?
- If the person exposed is a known responder to the HBV vaccine then a booster dose should be given
- If they are a non-responder (anti-HBs < 10mIU/ml 1-2 months post-immunisation) they need to have hepatitis B immune globulin (HBIG) and a booster vaccine
Hepatitis B PEP unknown source?
- For known responders the HBV vaccine the Green Book advises considering a booster dose of HBV vaccine
- For known non-responders HBIG + vaccine should be given whilst those in the process of being vaccinated should have an accelerated course of HBV vaccine
Hepatitis C PEP?
- Monthly PCR - if seroconversion then interferon +/- ribavarin
HIV PEP?
- The risk of HIV transmission depends heavily on the incident (e.g. needle stick, type of sexual intercourse, human bite etc) and the current viral load of the patient
- A combination of oral antiretrovirals (e.g. Tenofovir, emtricitabine, lopinavir and ritonavir) as soon as possible (i.e. Within 1-2 hours, but may be started up to 72 hours following exposure) for 4 weeks
- Serological testing at 12 weeks following completion of post-exposure prophylaxis
- Reduces risk of transmission by 80%
Varicella zoster PEP?
VZIG for IgG negative pregnant women/immunosuppressed
Listeria monocytogenes mushkies?
A Gram-positive bacillus which has the unusual ability to multiply at low temperatures. It is typically spread via contaminated food, typically unpasteurised dairy products. Infection is particularly dangerous to the unborn child where it can lead to miscarriage
Listeria features?
- Diarrhoea, flu-like illness
- Pneumonia, meningoencephalitis
- Ataxia and seizures
Listeria Ix?
- Blood cultures
- CSF may reveal a pleocytosis with ‘tumbling motility’ on wet mounts
Listeria Rx?
- Amoxicillin/ampicillin
- Listeria meningitis should be treated with IV amoxicillin/ampicillin and gentamicin
Listeria in pregnant women mushkies?
- 20 times more likely to develop listeriosis compared with the rest of the population due to changes in the immune system
- Fetal/neonatal infection can occur both transplacentally and vertically during child birth
- Complications include miscarriage, premature labour, stillbirth and chorioamnionitis
- Diagnosis can only be made from blood cultures
- Rx = amoxicillin
Enteric fever (typhoid/paratyphoid) organism?
Salmonella typhi and Salmonella paratyphi (types A, B & C) respectively. They are often termed enteric fevers, producing systemic symptoms such as headache, fever, arthralgia.
Salmonella gram stain?
Gram negative rod
Enteric fever transmission?
Faeco-oral route
Enteric fever features?
- Relative bradycardia
- Constipation more common in typhoid
- Rose spots in 40%, more common in paratyphoid
Enteric fever complications?
- Osteomyelitis (esp. in sickle cell)
- GI bleed/perforation
- Meningitis
- Cholecystitis
- Chronic carriage (1%, more likely if adult females)
Pre-hospital setting Meningitis Rx?
IM Benzylpenicillin
Meningitis < 3m Rx?
IV Cefotaxime + amoxicililn/ampicillin
Meningitis 3m - 50 y/o Rx?
- IV Cefotaxime/Ceftriaxone