Infectious Diseases Flashcards
What is candidiasis?
thrush
Features of candidiasis
- ‘Cottage cheese’, non-offensive discharge
- Vulvitis: superficial dyspareunia, dysuria
- Itch
- Vulval erythema
Investigations for vaginal candidiasis
a high vaginal swab is not routinely indicated if the clinical features are consistent with candidiasis
Management of vaginal candidiasis
1st line = single dose oral fluconazole
if contraindicated = intravaginal pessary clotrimazole
Vulval symptoms - topical imidazole with oral or intravaginal antifungal
What is cryptococcosis?
Opportunistic fungal infection
- Caused by environmental fungus found worldwide
- often found in soil contaminated with bird droppings
How does cryptococcosis infection present?
- Meningitis is the most frequently seen presentation
- Clinical manifestation can vary:
- Headache
- Lethargy
- Pyrexia
- Productive cough
- SOB
- personality changes will develop over 2-4 weeks (sometimes months)
Investigation for cryptococcosis
- Lumbar puncture will feature high opening pressure, lymphocytic CSF, high protein and low glucose
- CSF CrAg: Sensitivity 93 - 100%, Specificity 93 - 98%
- Gold standard diagnostic test is culture*
2. Serum Cryptococcal Antigen (CrAg) also used
3. India ink stain: round, encapsulated yeast
Gold standard diagnostic test for cryptococcosis
Culture!
Management of cryptococcosis
mild to moderate disease:
1st line = fluconazole (6-12 months)
Severe disease and CNS involvement:
Amphotericin B + Flucytosine followed by fluconazole
What is histoplasmosis?
Histoplasma capsulatum - another environmental fungus
- found worldwide
but most commonly America in soil with bird/bat droppings
How is histoplasmosis transmitted?
Via inhalation of microscopic spores, incubation 3-17d
Features of histoplasmosis
- Flu-like (fever/cough/lethargy/headache)
- Consider in patients with pneumonia and mediastinal LN, pulmonary nodule, pericarditis with LN, pulmonary manifestations with arthralgia
- Severity depends on host immunity and intensity of exposure
Investigations for histoplasmosis
1st line = CXR common findings for histoplasmosis pneumonia: - nodules - mediastinal or hilar lymphadenopathy - cavitary lesions - pleural effusions
Gold standard /Diagnostic:
Culture of pulmonary secretions
Other: Histoplasma antigen on serum or urine
Management of histoplasmosis
Asymptomatic, Mild + immunocompetent = observe
Mild + immunocompromised =
itraconazole (azole antifungals)
Severe (for acute pulmonary cases) = Amphotericin B followed by itraconazole
What is pneumocystis jiroveci pneurmonia also known as?
Pneumocystis carinii pneumonia (PCP)
- common opportunistic infection in AIDS
Featues of pneumocystis jiroveci
dyspnoea
dry cough
fever
very few chest signs
Investigations for pneumocystis jiroveci
- CXR:
- bilateral interstitial
pulmonary infiltrates
- lobar consolidation.
- May be normal - exercise-induced desaturation
- sputum often fails to show PCP
- bronchoalveolar lavage (BAL) = silver stain shows characteristic cysts
Most common complication of pneumocystis jiroveci
Pneumothorax
Management of pneumocystis jiroveci
- co-trimoxazole
- IV pentamidine in severe cases
- alternative: aerosolized pentamidine (less effective in pneumothorax) - steroids if hypoxic
What is Epstein-Barr virus?
Infectious mononucleosis (glandular fever)
EBV, also known as human herpesvirus 4, HHV-4
Features of EBV
Classic triad of :
- sore throat
- pyrexia
- lympadenopathy
- Symptoms typically resolve after 2-4 weeks
Diagnostic test for EBV
heterophil antibody test (Monospot test)
Management of EBV
- Management is supportive and includes:
o rest during the early stages, drink plenty of fluid, avoid alcohol
o simple analgesia for any aches or pains
o avoid playing contact sports for 8 weeks after having glandular fever to reduce the risk of splenic rupture
Types of herpes simplex virus
HSV-1 : oral lesions (cold sores)
HSV-2 for genital herpes
Features of HSV
- primary infection: may present with a severe gingivostomatitis
- cold sores
- painful genital ulceration
Management of HSV
- gingivostomatitis: oral aciclovir, chlorhexidine mouthwash
- cold sores: topical aciclovir
- genital herpes: oral aciclovir.
What is mumps?
Mumps is a caused by RNA paramyxovirus and tends to occur in winter and spring
How do mumps spread?
- by droplets
- respiratory tract epithelial cells → parotid glands → other tissues
- infective 7 days before and 9 days after parotid swelling starts
- incubation period = 14-21 days
Symptoms of mumps
- fever
- malaise, muscular pain
- parotitis (‘earache’, ‘pain on eating’): unilateral initially then becomes bilateral
Investigations of mumps
- Serum mumps IgM – Positive igM confirms diagnosis.
- Negative IgM does not rule out mumps infection
- Serum Mumps IgG
- Viral culture (Saliva)
- Consider CT Head if there are focal neurological symptoms
Management of mumps
- Self-limiting - rest
- paracetamol for high fever/discomfort
- notifiable disease
What is roseola infantum?
AKA as exanthem subitum is a common disease of infancy caused by the human herpes virus 6 (HHV6).
Features of Roseola infantum
- high fever: lasting a few days, followed later by a
- maculopapular rash
- Nagayama spots: papular enanthem on the uvula and soft palate
- febrile convulsions
- diarrhoea and cough
How is Roseola infantum diagnosed?
Clinical diagnosis
Treatment of Roseola infantum
Self-limiting
What is rubella AKA and causative organism?
AKA German measles, is a viral infection caused by the togavirus.
When is rubella infectious?
infectious from 7 days before symptoms appear to 4 days after the onset of the rash
Features of rubella
- prodrome, e.g. low-grade fever
- rash: maculopapular, initially on the face before spreading to the whole body, usually fades by the 3-5 day
- lymphadenopathy: suboccipital and postauricular
Gold standard for rubella
Serological and/or polymerase chain reaction (PCR) testing is the gold standard.
Management of Rubella
Self-limiting
Causative organism of Measles
RNA paramyxovirus
Transmission of Measles
- spread by droplets
- infective from prodrome until 4 days after rash starts
- incubation period = 10-14 days
Features of Measles
- prodrome: irritable, conjunctivitis, fever
- Koplik spots (before rash): white spots (‘grain of salt’) on buccal mucosa
- rash: starts behind ears then to whole body, discrete maculopapular rash becoming blotchy & confluent
- diarrhoea
Investigation of Measles
IgM antibodies can be detected within a few days of rash onset
Management of Measles
- mainly supportive
- admission may be considered in immunosuppressed or pregnant patients
- notifiable disease → inform public health
Causative organism of Erythema Infectiosum
Parvovirus B19 is a DNA virus which causes a variety of clinical presentations.
Symptoms of Erythema Infectiosum
- ‘slapped cheek’ rash
- An erythematous maculopapular rash on the trunk, back, and limbs may develop a few days after the facial rash
- This then fades to produce a lace-like, reticular rash.
- low-grade fever
- Prodromal viral infection prior to onset of rash
Investigations of Erythema Infectiosum
Only done in pregnant/immunocompromised patients = serology
Management of Erythema Infectiosum
Self-limiting
Causative organism of rabies
Rhabdoviridae family
What is rabies?
viral disease that causes an acute encephalitis
Features of rabies
- Prodrome: headache, fever, agitation
- Hydrophobia
- hypersalivation
Investigations for rabies
- Clinical suspicion
2. immunofluorescence from saliva/CSF or anti- rabies antibodies
Treatment of rabies
- Contact PHE
- Late-stage Rx:
- Symptomatic Mx:
Quiet
private room
benzodiazepines
haloperidol
analgesia
anti-cholinergics - At risk countries:
- HRIG
Define Cytomegalovirus Infections
Cytomegalovirus is part of the Herpesvirus family
- Primary infection presentation = EBV
How CMV transmitted?
Sex/close contact (URT & Urine) / blood/transplant
Features of CMV
Manifest as colitis, hepatitis, encephalitis, pneumonitis, retinitis
Investigations for CMV
Serology (IgM & IgG), CMV DNA PCR, Histology (‘inclusions’)
Treatment of CMV
- Supportive in immunocompetent
2. Antiviral in immunocompromised (Cidofovir/Foscarnet/Ganciclovir)
What pathogen causes influenza?
RNA virus - orthomyxoviridae
What are the symptoms of influenza?
- Coryzal symptoms
- Fever
- Headache
- Non-productive cough
- Sore throat
How is influenza diagnosed?
Clinical diagnosis
- viral culture - PCR
Management of influenza and indication for medication
Antivirals:
Selective use of antivirals : oral oseltamivir and inhaled zanamivir
Indication:
1) if able to start treatment within 48 hours of symptoms onset
2) Known circulation of virus in community
3) High-risk : pregnant, obese, > 65 + < 6 y.o, immunocompromised, comorbidities
Conservative:
- analgesia
- increase fluid intake
- rest
What is varicella-zoster infection?
Chickenpox
- shingles is reactivation of VZV (herpes zoster)
Symptoms of shingles
prodromal period
1. burning pain over the affected dermatome for 2-3 days
- fever, headache, lethargy
rash
1. initially erythematous, macular rash over the affected dermatome
- quickly becomes vesicular
- does not cross the midline.
Management of shingles
- Anti-viral if you are seeing the patient within 72 hours of the onset of the rash
- Acyclovir 800 mg po 5 times per day x 7d
- Pain control
- Opiates
- Anticonvulsants
- Tramadol
- ? steroids
Facts about salmonellosis
Leading cause of foodborne illness
(poultry, eggs, milk products)
- Incubation period 8-72h post exposure (ingestion of contaminated food/water)
Features of salmonellosis
- Diarrhoea
- Nausea
- Vomiting
- Fever
- abdo cramps
Investigation for salmonellosis
Stool Microscopy, Culture & Sensitivities (MCS)
Management of salmonellosis
- Often self-limiting, 4-10d. <5% develop bacteraemia
- Supportive (hydration
- if severe – Ciprofloxacin/Azithromycin
- Isolate until 48 hours after the last episode of diarrhoea or vomiting
- Notifiable disease
What is shigellosis?
Shigella species cause a diarrhoeal illness
Transmission of shigellosis
Faeco-oral transmission, can be sexually acquired
Features of shigellosis
- Diarrhoea (often bloody)
- fever
- abdominal pain
Investigation for shigellosis
Stool MCS
Management of shigellosis
- Cipro/Azithro if unwell
2. Hand hygiene, Notify
Causative organism of tetanus
tetanospasmin exotoxin released from Clostridium tetani
How does tetanus affect the body?
Prevents release of GABA
How is tetanus transmitted?
Spores of the bacteria enter the body through a wound
Features of tetanus
- painful muscle contractions esp Masseter and neck muscles
- prodrome: fever, lethargy, headache
- trismus (lockjaw)
- risus sardonicus (distorted grin)
- opisthotonus (arched back, hyperextended neck)
- spasms (e.g. dysphagia)
Management of tetanus
- Supportive: ventilatory support, muscle relaxants
- wound debridement
- Metronidazole
- NB Tetanus does not confer immunity post infection, re-vaccinate every 10 years
Diagnosis of tetanus
clinical
What is cholera?
Acute diarrhoeal illness caused by toxin-producing strains of gram negative Vibrio cholerae.
How is cholera transmitted?
ingesting contaminated food or water
Features of cholera
- Diarrhoea - profuse ‘Rice water stool’
- Dehydration
- hypoglycaemia
Management of cholera
- Aggressive volume repletion (oral or IV)
- adequate nutrition
- antibiotics for severe cases = doxycycline, ciprofloxacin
Investigation for cholera
- Largely clinical
2. Stool MCS
Causative organism for diphtheria
Gram-positive bacillus Corynebacterium diphtheriae
Features of diphtheria
- sore throat –> with diphtheric membrane’ : grey pseudomembrane on the posterior pharyngeal wall
- bulk cervical lymphadenopathy –> ‘bull neck’
- low-grade fever
Investigation for diphtheria
Culture of throat swab: uses tellurite agar or Loeffler’s media
Management of diphtheria
- intramuscular penicillin
- Erythromycin - diphtheria antitoxin
- Notify
- Contact trace + prophylaxis
What is botulism?
Rare, but potentially life-threatening neuroparalytic syndrome caused by a neurotoxin of Clostridium botulinum
Features of botulism
Acute onset bilateral cranial neuropathies with symmetric descending weakness
- patient usually fully conscious with no sensory disturbance
- flaccid paralysis
- diplopia
- ataxia
- bulbar palsy
Investigation for botulism
Clinical suspicion, anaerobic culture
Management of botulism
Botulism antitoxin and supportive care
- antitoxin is only effective if given early - once toxin has bound its actions cannot be reversed
What is Atypical Mycobacterial Disease?
Opportunistic infection
E.g. Mycobacterium avium and Mycobacterium kansasii
- context of HIV, CD4 <50 are at higher risk of disseminated disease
- environmental organism
Transmission of Atypical Mycobacterial Disease
Transmission occurs via the respiratory or GI tract
Features of Atypical Mycobacterial Disease
- fever, night sweats, weight loss, lymphadenopathy, hepatomegaly
- Anaemia, leucopenia, hypoalbuminaemia
Investigation for Atypical Mycobacterial Disease
Mycobacterial cultures (blood/bone marrow/lymph node/ sputum/stool)
Management of Atypical Mycobacterial Disease
Clari-/Azithromycin) + Ethambutol + Rifabutin for > 3mo
Causative organis of threadworks
Infestation with threadworms (Enterobius vermicularis, sometimes called pinworms) is extremely common amongst children in the UK.
Transmission of threadworms
Infestation occurs after swallowing egg
Features of threadworms
Usually asymptomatic
- perianal itching, particularly at night
- girls may have vulval symptoms
How do you diagnose threadworms?
Cellophane test/ Clinical suspicion
Treatment for threadworms
1st line = Mebendazole with repeat dose in 2/52
- Treat entire family, hygiene measures
What is hookworm?
Hookworm (Ancylostoma duodenale and Necator americanus) as well as Ascaris (up to 35mm) and Trichuris (whipworm) are all soil-transmitted helminths account for the majority of infection
Transmission of hookworm
Mainly acquired through walking barefoot in contaminated soil
Features of hookworm
- Majority asymptomatic
- Some GI symptoms
- anaemia
- mild cough
- serum eosinophilia
Investigation for hookworm
Stool Ova, Cysts and Parasites
Treatment of hookworm
Albendazole or Mebendazole
Causative organism of amoebiasis
Entamoeba histolytica
Transmission of amoebiasis
Spread by the faecal-oral route
Symptoms of amoebiasis
- Infection can be asymptomatic
- cause mild diarrhoea
- severe amoebic dysentery
Sx, Ix & Mx of amoebic dysentery
- profuse, bloody diarrhoea
Ix: stool microscopy may show trophozoites if examined within 15 minutes or kept warm (known as a ‘hot stool’)
Mx: metronidazole
Causative organism of malaria
Mosquito-borne infection caused by Plasmodium protozoa
Four kinds of malaria parasite: Plasmodium falciparum, P. vivax, P. ovale and P. malariae
Features of malaria
- Fever, arthralgia, headache, nausea, abdominal pain (often non-specific symptoms)
- Signs: Tachycardia, tachypnoea, fever, anaemia, thrombocytopenia, transaminitis, splenomegaly
Management of malaria
Urgent prompt IV therapy, inform senior, if DGH consider referral to Tertiary referral centre, inform ITU
Depends on severity of falciparum malaria
(CHECK NOTES)
Management of falciparum malaria
1st line = artemisinin-based combination therapies (ACTs)
Severe:
IV artersunate
? bacterial septicaemia if haemodynamic collapse
Management of non- falciparum malaria
1st line = artemisinin-based combination therapy (ACT) or chloroquine
Give Primaquine following acute treatment with chloroquine to destroy liver hypnozoites and prevent relapse.
Causative organism of toxoplasmosis
Infection with a worldwide distribution caused by Toxoplasma gondii
Transmission of toxoplasmosis
- Ingestion of infectious oocysts from soil/water
- Ingestion of tissue cysts in the meat of an infected animal
- Vertical transmission
- Transmission from organ transplantation from an infected donor
Features of toxoplasmosis
- Immunocompetent person: primary infection usually asymptomatic
- If symptomatic: fever, sweats, headache, myalgia, hepatosplenomegaly
- Most common manifestation is bilateral, symmetrical non-tender cervical lymphadenopathy
- Labs: Lymphocytosis, raised LFTs, moderate increase in CRP
Investigations of toxoplasmosis
Serology
Management of toxoplasmosis
no treatment unless severe infection or immunosuppressed
Tx: pyrimethamine and sulfadiazine
Advice: avoid raw/undercooked meat, avoid changing cat litter
