General ID AB Flashcards
What is the incubation period of P. falciparum?
7-28 days
What are the features on blood film of P falciparum?
Multiple infected RBC
No enlargement of RBC
Crescent-shaped gametocytes
Ring-forms (chromatin)
What are the features on blood film of P vivax?
Few infected RBC
Swollen infected RBC
Fine eosinophilic dots (Schuffner’s dotsS)
Round/oval gametocytes
Give an example of the genetic basis of drug resistance in malaria.
Mefloquine & lumefantrine
- Pfmdr1 gene
Chloroquine
- Pfmdr1 gene
- Pfctr transporter
- K76T
Antifolate drugs
- point mutations in DHFR and DHTS
Give two common effects of malaria in pregnancy
Spontaneous abortions
IUGR
What are the severe manifestations of malaria?
Unable to tolerate oral intake Altered consciousness >5% parasitaemia Jaundice Oligura Hypoglycaemia Severe anaemia Acidosis ARDS
How long from illness onset does severe disease manifest?
3-7 days after illness onset
What is the mortality rate of severe malaria?
15-25%
What findings may you see on CBE in malaria?
Haemolytic anaemia
WCC normal/low
- No eosinophilia
Thrombocytopaenia (95%)
What is the management of severe P. falciparum?
IV Artesunate
IV quinine second line
What are some adverse drug reactions of IV Artesunate?
Cerebellar ataxia
Abdominal pain
Diarrhoea
ALT elevation
What comorbidity do you need to exclude prior to commencing quinine therapy?
G6PD deficiency (haemolysis)
How do you treat uncomplicated P falciparum?
First line: Artemether-Lumefantrine (Riamet)
- >95% cure rate in P falciparum
Second line: atovaquone-proguanil (Malarone)
- Slower parasite clearance
Third line: quinine + doxy/clindamycin
How do you treat P vivax/malariae/ovale?
Chloroquine
What are the options for chemoprophylaxis in malaria?
Chloroquine
- 1 week prior to 4 weeks after
Atovaquone + proguanil (malarone)
- 1-2 days prior, 7 days after
Doxycycline
- 2 days prior to 4 weeks after
- Can use in Mefloquine-resistant malaria (SEA)
What are the contraindications for Mefloquine?
Neuropsychiatric disorders
Epilepsy
Cardiac conduction defects
How do you treat Amoebiasis?
Metronidazole
Paromomycin or diloxanide fuorate (prevents continued luminal infection)
What family of viruses does Ebola belong to?
Filovirus family
Zaire - current outbreak
What is Ebola’s incubation period?
11 days (6-12)
How to you test for Ebola?
Viral PCR
- positive 1 day prior to symptoms
What is the pathophysiology of ebola?
- Binds to surface receptors
- Internalised by macropinocytosis
- Moved to Endosomal compartments
- Viral GP2 interacts with NPC1
- Fusion of viral and endosomal membrane
- Viral nucleocapsid released into cytoplasm
- Genome is replicated
What is the incubation period of Influenza?
1-3 days
Antigenic shift - what does this cause in a population?
Pandemic
Antigenic drift - what does this cause in a population?
Annual epidemic
What are some extra-pulmonary sequelae of influenza?
Myositis GBS Encephalitis Reye syndrome - mostly influenza B + aspirin
Meningococcal meningitis - what is the treatment?
IV Benpen 1.8g 4 hourly (short course)
Cipro if type 1 penicillin hypersensitivity
Meningococcal meningitis - what is the mortality?
7% (on treatment)
N meningitidis - what is the microbiology?
Gram negative diplococci
neiserria = negative
Meningococcal meningitis - what is the incubation period?
2-10 days
Pneumococcal meningitis - what is the treatment?
Empiric - Ceph + Vanc
L monocytogenes meningitis - what is the incubation?
Long - up to 6 weeks
L monocytogenes meningitis - what is the treatment?
Benpen (resistant to Ceph)
Resistant: TMP/SMX
Cryptococcal meningitis - what is the treatment?
Induction: Amphoterecin B + Flucytosine
Consolidation: Fluconazole
Minimum 10 weeks therapy
Hib meningitis - what is the treatment?
Ceftriaxone for 7 days
+ Benpen for 7 days if susceptible
Steroids - what is the proven efficacy in meningitis?
Hib - hearing loss in children
S pneumo - mortality benefit
No benefit in meningococcal.
Diffuse erythematous rash - what are some infective causes?
Scarlet fever (strep) Toxic shock syndrome (staph or strep) Staph scalded skin syndrome Dengue Enterovirus
Purpuric rash - what are some infective causes?
Meningococcus Gonococcus Staph sepsis Dengue HBV Enterovirus Rickettsial infection
Cellulitis - what are the associated exposures with:
- Dog/cat bite
- Fresh water
- Sea water
- Immunocompromised
- Shell fish
- Other water exposure
- Dog/cat bite - pasturella
- Fresh water - aeromonas (esp males with cirrosis/cancer)
- Sea water - vibrio
- Immunocompromised - clostridia
- Shell fish - erisepelothrix
- Other water exposure - mycobacterium marinum
Necrotising fasciitis - what is empiric therapy?
Meropenem
Penicillin
Clindamycin
Hyposplenism - name some causes
Haematologic disorders - CLL, sickle cell, lymphoma Splenic irradiation high dose steroids Coeliac disease Bone marrow transplant - Especially if GvHD
Name 4 encapsulated organisms
St pneumoniae
N meningitidis
H influenzae
Capnocytophaga carimorus
Toxoplasmosis - what is the treatment?
Pyrimethamine/folinic acid and sulfadiazine or clindamycinc
Zygomycosis - what is the treatment?
Debridement and amphotericin (lipid formulations)
Varicella - what is the incubation period?
10-21 days
Schistosomiasis - which organism infects the urinary tract?
S haematobium
Schistosomiasis - which organisms infect the bowel?
S masonii, S japonicum, S intercalatum
Schistosomiasis - what is the typical clinical picture?
Days: pruritic rash
Weeks later: febrile illness
Months/years later: fibrotic response in urinary tract or gut
Chronic infection: colitis, portal HT, urolithiasis, SCC bladder
Schistosomiasis - what is the management?
Praziquantel
Ascariasis - what sort of organism?
Helminthic (most common human)
Ascariasis - what is the management?
Mebendazole, pyrantel pamoate
Melioidosis - what is the organism?
Burkholderia pseudomallei
Melioidosis - what are the risk factors for infection?
DM
EtOH
Melioidosis - what are the clinical manifestations?
Pneumonia Abscesses (spleen, prostate) Osteomyelitis, septic arthritis Skin and soft tissue infection High mortality if sepsis
Melioidosis - what is the management?
Ceftazadime, Carbapenem
GCSF in sepsis
H pylori and gastric adenocarcinoma - which molecules/genes are involved?
CagA gene Vacuolating cytotoxin (vacA)
HPV - which strains are most likely to cause cervical cancer?
16 and 18
EBV and Burkitt’s lymphoma - which chromosome is affected?
Chromosome 8 translocation - deregulation of c-MYC oncogene
EBV - what are the associated malignancies?
Burkitt’s lymphoma
Hodgkin’s lymphoma
NHL in immunocompromised
Nasopharyngeal carcinoma
HHV-8 - what are the associated malignancies?
Kaposi sarcoma
Primary effusion lymphoma
Multi-centric Castleman’s disease
Schistosomiasis - what is the associated malignancy?
SCC of the bladder
What is the Jarish-Herxheimer reaction?
Fever and transient exacerbation of constitutional symptoms from sudden release of bacterial products from injured or killed bacteria
Seen with tertiary syphilis, brucellosis, enteric fever, schistosomiasis.
