Infectious Diseases Flashcards
Pneumonia + Alcoholic + Cavitation =
Pneumonia + Prior Flu =
Pneumonia + Chicken Pox Rash =
Pneumoniae Pneumonia + Hemolytic Anemia =
Pneumonia + Hyponatraemia + Travel History =
Pneumonia + Fleeting opacities =
Pneumonia + Fits/LOC =
Pneumonia + HSV oral lesion =
Pneumonia + parrot =
Pneumonia + farm animals =
Pneumonia + HIV =
Pneumonia + Cystic fibrosis =
Pneumonia + COPD or exac =
Pneumonia + Alcoholic + Cavitation = Klebsiella
Pneumonia + Prior Flu = Staph Pneumonia
Pneumonia + Chicken Pox Rash = Varicella
Pneumoniae Pneumonia + Hemolytic Anemia = Mycoplasma
Pneumonia + Hyponatraemia + Travel History = Legionella
Pneumonia + Fleeting opacities = Cryptogenic Pneumonia
Pneumonia + Fits/LOC = Aspiration Pneumonia
Pneumonia + HSV oral lesion = Strep Pneumonia
Pneumonia + parrot = Chlamydia psitatssi
Pneumonia + farm animals = Q fever (coxillea brunetii)
Pneumonia + HIV = think pcp but if straight forward case strep pneumonia is still most common
Pneumonia + Cystic fibrosis = consider pseudomonas/Burkholderia
Pneumonia + COPD or exac = c1::Haemophilus Influenza
Commonest cause of CAP =
Strep Pneumonia
What infections can cause caveatting lesions in the lungs? (4)
Staph aureus
Klebsiella
TB
Aspergillosa
What should you do if you have a needlestick from suspected/confirmed Hep B patient?
If responder to vaccine -> need a booster
If non-responder -> need Hep B immunoglobulins + vaccine
If only had one jab so far -> need Hep B immunoglobulins + vaccine
What should you do if you have a needlestick from suspected/confirmed Hep C patient?
monthly PCR - if seroconversion then protease inhibitors +/- ribavirin PO
What should you do if you have a needlestick from suspected/confirmed Hep A patient?
Human Normal Immunoglobulin (HNIG) or hepatitis A vaccine may be used
What should you do if you have a needlestick from suspected/confirmed HIV patient?
a combination of PO antiretrovirals (e.g. Tenofovir, emtricitabine, lopinavir and ritonavir) asap (i.e. within 1-2 hrs, but may be started up to 72 hrs) for 4 weeks
serological testing at 12 wks following completion of PEP
reduces risk of transmission by 80%
What should you do with pregnant women/IC if exposed to varicella zoster?
If pregnant – check Abs
- If <20wks + not immune, give VZIg
- If >20wks + not immune, give VZIg or aciclovir from day 7-14
- If develops chickenpox, give PO aciclovir if >20wks and 24hrs since onset of rash
- Consider the above if <20wks pregnant
How to treat human and animal bites?
Co-amox
if penicillin-allergic then doxycycline + metronidazole
What is the most common organism that may infected a patient following an animal bite?
Pasteurella multocida
What is the most common organism that may infected a patient following a human bite?
Human bites commonly cause multimicrobial infection
Which bacteria cause fish tank granulomas?
Mycobacterium marinum
Which HIV patients should receive prophylaxis for PCP?
all patients with a CD4 count < 200/mm³
What is a common complication of PCP?
Pneumonthorax
Name the gram positive rods?
ABCD-L
Actinomyces
Bacillus anthraces
Clostridioides spp
Diphtheria
Listeria
What are the five types of malaria?
Plasmodium vivax – most © non-falciparum
Plasmodium ovale – more © Africa
Plasmodium malariae – associated with nephrotic syndrome
Plasmodium falciparum ©-est! – often causes severe malaria
Plasmodium knowlesi
Protective conditions/genetics for malaria?
- SCA
- G6PD deficiency
- HLA-B53
Malaria host?
Female Anopheles mosquito
Features of severe malaria?
schizonts on a blood film
parasitaemia > 2%
hypoglycaemia
acidosis
temperature > 39 °C
severe anaemia
complications: cerebral malaria, renal failure, ARDS, DIC
STARCHS
What type of fever might you see with the non-falciparum malarias?
Plasmodium vivax/ovale: cyclical fever every 48 hours
Plasmodium malariae: cyclical fever every 72 hours
Knowlesi: every 24 hours
Which malaria prophylaxis to give pregnant women?
Chloroquine
Which malaria prophylaxis to give children?
DEET
Doxy if >12yo
Treatment of severe malaria?
IV artesunate (alternative = quinine) - If parasite count \>10%, consider exchange transfusion
Treatment of uncomplicated falciparum malaria?
artemisinin combination therapies (ACT) e.g. artemether-lumefantrine
Treatment of non-falciparum malaria?
chloroquine (P. vivax + ovale) + primaquine (to eradicate liver hypnozoites)
Investigations in malaria?
Thick blood smear – locates parasites in RBCs
Thin blood smear – directly identifies the plasmodium species
Bloods may show:
- Thrombocytopaenia
- Elevated LDH
- Normochromic, normocytic anaemia
- Normal WCC
Mechanism by which malaria affects the body?
Mosquito gets infected by gametocytes
Plasmodium resides in salivary glands -> injected into humans when bitten
Exoerythrocytic Phase - asymptomatic
Over 1-2 weeks undergoes asexual reproduction in the liver
May then go dormant for months/years (P. vivax/ovale)
Erythrocytic Phase
Released into blood -> invade RBCs
P. vivax only invades reticulocytes
P. malariae only invade old RBCs
Undergo more reproduction
RBC bursts and releases contents
This happens in waves in tune with reproductive cycles -> causes a ‘swinging fever’
Haemolytic anaemia happens as a results and is responsible for fatigue, headaches, jaundice, splenomegaly
What might you see in the CSF in Listeria?
CSF may reveal a pleocytosis, with ‘tumbling motility’ on wet mounts
How to treat listeria infection incl in the case of meningitis?
Listeria is sensitive to amoxicillin/ampicillin (cephalosporins usually inadequate)
Listeria meningitis should be treated with IV amoxicillin/ampicillin and gentamicin
What type of virus is hep C?
RNA flavivirus
What test to confirm exposure and then ongoing infection in Hep C?
HCV Abs confirms exposure
HCV-RNA PCR confirms ongoing infection/chronic
If HCV-PCR positive, what further investigation should you do?
Transient elastography to assess for liver damage
How to treat Hep C?
Avoid alcohol
Combination therapy: protease inhibitors +/- ribavirin PO
- Virus is cleared in 95% of patients
- Ribavirin = teratogenic, women should not become preg within 6m
Liver transplantation may be considered
Aim for undetectable viral load
Complications of Hep C?
- Arthralgia/arthritis
- Sjogren’s syndrome
- Cirrhosis/HCC
- Cryoglobulinaemia (type 2)
- Porphyria cutanea tarda
Features of campylobacter GI infection?
A flu-like prodrome usually followed by crampy abdo pains, fever + diarrhoea (may be bloody)
May mimic appendicitis
Management and complication of campylobacter?
Complications include GBS
Mx: clarithromycin
What to offer a chlamydia contact?
Offer Chlamydia testing and antibiotic treatment immediately without waiting for the results
What is the causative organism for Q fever?
Coxiella burnetii
How do you treat Q fever?
doxycycline
What type of people get Q fever?
Farmers
Typically caught from cattle/sheep or inhaled from infected dust
What type of virus is measles?
RNA paramyxovirus
What is the measles incubation period?
10-14 days
When is measles infective?
from prodrome -> 4/7 of rash
What are the features of measles?
Prodrome: fever, irritable, conjunctivitis
Koplik spots on buccal mucosa – before rash
Rash – starts behind ears, maculopapular -> blotchy
Diarrhoea in 10% of patients
Complications of measles?
Otitis media ©
Pneumonia – most © cause of death
Encephalitis – typically 1-2wks after illness onset
Subacute sclerosing panencephalitis – may occur 5-10yrs later
- Fatal within 1-3yrs
Febrile convulsions
Keratoconjunctivitis
Myocarditis/appendicitis
Most common causative organism of travellers diarrhoea?
E. coli
Cause of prolonged, non-bloody diarrhoea?
Giardiasis
Cause of profuse, watery diarrhoea + severe dehydration resulting in WL?
Cholera
Cause of bloody diarrhoea, vomiting and abdo pain?
Shigella
Symptoms of bacillus cereus infection?
Two types of illness are seen
• Vomiting within 6 hours (often d/t rice)
• Diarrhoeal illness occurring after 6hrs
Incubation periods for common gastro bugs?
- 1-6 hrs: Staphylococcus aureus, Bacillus cereus
- 12-48 hrs: Salmonella, E. coli
- 48-72 hrs: Shigella, Campylobacter
- >7 days: Giardiasis, Amoebiasis
How is giardiasis spread?
Faeco-oral route
Symptoms of giardiasis?
Often asymptomatic
Lethargy, bloating, abdo pain
Flatulence
Non-bloody greasy chronic diarrhoea -> due to malabsorption
Investigation in giardiasis?
duodenal fluid aspirates or ‘string tests’ (fluid absorbed onto swallowed string) are sometimes needed
Stool tests are often negative
Treatment of giardiasis?
Metronidazole
Which vaccines are CI in HIV positive patients?
Cholera intranasal
Poliomyelitis-oral
Tuberculosis (BCG)
TCP
Which vaccines are not given if CD4 <200?
MMR
Varicella
Yellow fever
What type of virus is Orf?
Parapox virus
What are the features of Orf?
Affects hands/arms
Small raised red-blue papules -> 2-3cm flat-topped + haemorrhagic
Features of hand, foot and mouth disease?
Sore throat/fever
Oral ulcers
Followed by vesicles on the palms and soles of the feet
How to treat cerebral toxoplasmosis in IC pts?
pyrimethamine + sulphadiazine for 6wks
Nothing in patients without immunocompromise
What are the two different types of trypanosomiasis?
African trypanosomiasis (sleeping sickness) American trypanosomiasis (Chagas' disease)
What are the two different types of african trypanosomiasis?
Trypanosoma gambiense (West Africa) Trypanosoma rhodesiense (East Africa) - the Gambia is in West Africa
How is trypanosomiasis spread?
Tsetse fly
Features of African trypanosomiasis?
Trypanosoma chancre – at site of infection
Intermittent fever
Posterior cervical lymphadenopathy
Later: CNS involvement – headache, mood changes, meningoencephalitis
Management of African trypanosomiasis?
early disease: IV pentamidine or suramin
later disease or CNS involvement: IV melarsoprol
Features of Chagas disease?
95% are asymptomatic
chagoma (an erythematous nodule at site of infection) and periorbital oedema are sometimes seen
Chronic infection with Chagas Disease complications?
Myocarditis -> dilated cardiomyopathy and arrythmias
GI features -> megaoesophagus/megacolon causing dysphagia + constipation
Management of Chagas Disease?
Acute phase - benznidazole or nifurtimox
Chronic phase – treating the complications
Investigations of PCP?
CXR – bilateral pulmonary infiltrates Bronchoalveolar lavage (BAL) often needed to demonstrate PCP – use silver stain
Management of PCP?
Co-trimoxazole
IV pentamidine for severe cases
Steroids if hypoxic
Common complication of PCP?
Pneumothorax
What bug causes Lyme disease?
Caused by Borrelia burgdorferi
Presentation of Lyme disease?
Early – erythema chronicum migrans (target) rash (seen in 80%), headache, fever, arthralgia
CVS – heart block, myocarditis
Neuro – facial nerve palsy, meningitis
Investigations for Lyme disease?
Clinical Dx
ELISA for Abs (IgG + IgM)
- If negative, can repeated 4-6wks after the first
If +ve (or -ve but high suspicion), then immunoblot test (western blot) should be done
Management of Lyme disease?
Doxycycline if early disease
If CI, give Amoxicillin (e.g. pregnancy)
Ceftriaxone if disseminated disease
What is the Jarisch-Herxheimer reaction?
sometimes seen after initiating therapy in Lyme disease/syphilis
- Reaction produced from the death of microorganisms on starting abx (endotoxin-like)
- Fever, rash, tachycardia
- No treatment needed
In addition to 12-13yo girls (and now boys), who else should be given the HPV vaccine?
HPV vaccination should also be offered to men who have sex with men under the age of 45 to protect against anal, throat and penile cancers
Which HPV strains are you protected against with the vaccine?
6, 11, 16 and 18
Which bacteria are gram negative cocci?
Neisseria meningitidis + Neisseria gonorrhoeae, also Moraxella catarrhalis
Which bacteria are gram positive cocci?
staphylococci + streptococci (including enterococci)
What percentage of hep C will turn chronic?
55-85%
Other than usual pneumonia symptoms, what symptoms might you get in legionella pneumonia?
relative bradycardia
confusion
hyponatraemia
deranged LFTs
pleural effusion: seen in around 30% of patients
How to investigate legionella?
Urinary antigen
Management of legionella?
erythromycin/clarithromycin
What class of bacteria is H. influenzae in?
gram negative coccobacilus
Staph, coagulase negative vs positive example?
Coag -ve: S. epidermidis
Coag +ve: S. aureus
What to do if <20 weeks pregnant and exposed to varicella with no previous infection?
Give immunoglobulins
What is Lemierre’s syndrome?
an infectious thrombophlebitis of the internal jugular vein
What causes Lemierre’s syndrome?
occurs secondary to a bacterial sore throat caused by Fusobacterium necrophorum leading to a peritonsillar abscess. A combination of spread of the infection laterally from the abscess and compression lead to thrombosis of the IJV.
Presentation of Lemierre’s syndrome?
history of bacterial sore throat followed by neck pain, stiffness and tenderness (may be mistaken for meningitis) and systemic involvement (fevers, rigors, etc)
Complication of Lemierre’s syndrome?
Septic pulmonary emboli
What type of bug causes schistosomiasis?
Parasitic flatworm
What are the acute symptoms of schistosomiasis?
• Swimmers itch
• Acute schistosomiasis syndrome (Katayama fever)
o Fever
o Urticaria
o Arthralgia
o Cough
o Diarrhoea
o Eosinophilia
What does schistosoma haematobium do and what complications can it lead to?
Deposit eggs clusters in the bladder -> inflammation + calcification
- causes frequency/haematuria
o Can cause obstructive uropathy/kidney damage
o Risk of bladder SCC
What does Schistosoma mansoni + Schistosoma japonicum do?
Mature in liver - travel through portal system to distal colon
o Can cause progressive hepatomegaly + splenomegaly due to portal vein congestion
o Can also cause liver cirrhosis, variceal disease + cor pulmonale
How do you manage schistosomiasis?
Praziquantel
What to do if IC individual e.g. on Mtx, is exposed to varicella?
Check Abs
Give VZIg if -ve
Don’t delay giving VZIg past 7/7 whilst waiting for Abs
What type of virus is Rabies?
RNA rhabdovirus
What are the symptom of Rabies?
Headache, fever, agitation
Hydrophobia
Hypersalivation
What is seen on microscopy in Rabies?
Negri bodies: cytoplasmic inclusion bodies found in infected neurons
How to treat Rabies?
Wash wound
Two further doses of vaccine required
If not previous immunised, human rabies immunoglobulin should be given alongside full course of vaccination
How do strongyloides travel through the body?
Worm enters through the skin -> travels to the lungs -> trachea -> pharynx -> is swallowed to the small intestine and lays eggs in the mucus
What are the features of strongyloidiasis and what is the name of the skin condition?
Diarrhoea
Abdo pain/bloating
Papulovesicular lesions where larvae have penetrated e.g. soles/buttocks
Larvae currens – the path of the worm below the skin, disappears
How to treat strongyloidiasis?
Ivermectin
Albendazole
Which organism are usually responsible for PID?
Chlamydia trachomatis
Neisseria gonnorrhoeae
Mycoplasma genitalium
Mycoplasma hominis
Features of PID?
Abdo pain
Fever
Deep dyspareunia
Dysuria + menstrual irregularities
Vaginal or cervical discharge
Cervical excitation
Investigations in PID?
Preg test to exclude an ectopic
High vaginal swab
Screen for Chlamydia/Gonorrhoea
Management of PID?
Low threshold for treatment
PO oflaxacin + PO metronidazole
Or IM ceftriaxone + PO doxycycline + PO metronidazole
Consider removal of IUD
Complications in PID?
Perihepatitis (Fitz-Hugh Curtis Syndrome)
- Occurs in 10% of cases
- RUQ pain
Infertility
Chronic pelvic pain
Ectopic pregnancy
Incubation period for chickenpox?
10-21 days
Infective period for chickenpox?
4/7 before rash -> 5/7 after rash
Management of chickenpox?
Calamine lotion
School exclusion – until lesions have crusted
IC patients/newborns should receive VZIg if Ab negative
Consider IV aciclovir
Complications of chickenpox?
Secondary bacterial infection
- NSAIDs may increase risk
- Risk: group A strep soft tissue infection -> nec fasc
Pneumonia – most © complication, ausculatation often unremarkable
Encephalitis
A little similar to measles
What bacteria causes chlamydia?
Chlamydia trachomatis
What are the symptoms of chlamydia if any?
Urethritis and vaginal discharge
Ix for chlamydia?
NAAT testing
Women - high vaginal swab
Men - urine
Management of chlamydia? What if pregnant?
Doxycycline - 1st line
Azithromycin
Preg - azithro/erythro/amoxicillin
Complications of chlamydia?
Reactive arthritis
PID
What bacteria causes thrush?
Candida albicans
What are the RFs for thrush?
Pregnancy
Diabetes
Antibiotics
What are the symptoms of thrush?
Cottage cheese discharge
Vulval irritation + itching
May also have sup dyspyrunia + dysuria + inflamed/red vagina or vulva
Ix for thrush?
High vaginal swab
Management of thrush?
Clotrimazole/PO fluconazole
What is the main organism to cause BV?
Gardnerella vaginalis
What are the symptoms of BV?
Grey-white discharge
Fishy odour
NOT itchy/red