ID Flashcards
What are the two possibilities seen if a gram positive organism is looked at down the microscope
How are gram positive cocci further defined? How do they look under a microscope?
Bacilli
Cocci
Catalase test- staph- positive- clusters
Strep- negative- chains
What are 2 gram positive bacilli and how are they defined
Anaerobic- clostridium
Aerobic- listeria
What are the 2 ways strep are classified
Haemolysis- alpha is total, beta is partial and gamma is none
Lancfield- a,b,d and e
What is an example of
Group A strep
Group B strep
Group E&F strep
Partial haemolysis
Total haemolysis
No haemolysis
Pyogenes
Agalactiae
Viridans and pneumonia
Groups E and F
Groups A and B
Enterococcus
What is the most severe form of malaria
What are the most common other 2 forms called? What makes them be able to be latent?
Falciparum
Vivax and ovale- hypnosis tests unhook
What does chickungunya cause
Febrile convulsions
What causes Chagas’ disease
What does it cause
Trypansoma Cruzi
Myocarditis
What is seen on uss with Zika virus other than anencephaly
Subcortical calcifications
How does malaria normally present?
What indicates severe disease?
Fever, haemolytic anaemia, myalgia and malaise
Drowsiness headache and vomiting
Malaria- what is the difference between thick and thin films?
Thick films- counts how many rbc infected
Thin- what species is involved
How is malaria treated?
What is normal prophylaxis?
Why does prophylaxis differ in east Africa? What is used instead?
Chloroquine or artemisinin based therapies
Mefloquinine
Likely chloroquine resistance therefore give malarone
What causes typhoid
What protects against it?
What are two characteristic features?
Salmonella enteritica
CF
Salmon pink rash and diarrhoea
What type of virus causes dengue?
How does it present
How does haemorrhagic fever present?
Flavivirus
Biphasic breakback fever with rash and oedema of extremities
Shock with bleeding bruising and petechiae
What is the most likely bug to cause septic arthritis or osteomyelitis?
What is more likely in toddlers
Which bug is more likely in sickle cell
Where is the most common site
Staph aureus
Kingella
Salmonella
Lower limbs
Osteomyelitis
What might you see on X-ray
Fat pads, lytic lesions periosteal elevation
Osteomyelitis- length of treatment
Septic arthritis-“
Discitis-“
OM- 3-4
SA- 2-3
6 weeks
TB
What are the three phases and what will be seen in each
1) exposure- no symptoms and signs, all tests negative
2) primary infection- no symptoms and signs but chest X-ray may have Hohn focus or be normal and TST positive
3) disease- symptoms signs abnormal chest X-ray and tst positive
TB
What are the features in cxr
How does it differ from adults
Bilateral hilar lymphadenopathy
Atelectasis
Consolidation
Any lobe is involved
No calcification
What is miliary TB
What other infection might make it more common?
Disseminated disease involving multi organs. Lymphohaematogenous spread
HIV/AIDS
What is measured in the mantoux test?
How long after exposure does it become positive
What might give a false negative
Area of induration
3w to 3 months
Incorrect admin, reading it wrong, having a bcg previously, doing it too early
What are two benefits of quantiferon gold to TST?
Only need one visit
Won’t pick up vaccinated people
Mantoux test size, when is it positive
>5mm
>10mm
>15mm
Very high risk exposure or cxr changes
Young or other chronic disease, likely living in a high risk area
No other risk factors
TB
WHO recommended treatment
Recommendations for all exposed kids
6 months RI with PE in the first 2 months
3 months treatment then test. If negative give BCG. If positive complete course
Rifampicin
Side effects
What medications does it effect? How? Why?
Orange secretions
Hepatitis especially with isoniazid
P450 induced so reduces OCP
Isoniazid
Side effects
What might help?
Hepatitis
Peripheral neuropathy
Vitamin b6- pyrodoxine
Pyrazinamide
Side effects
GI upset
Hepatitis
Ethambutol
Side effects
Will they resolve when the meds are stopped?
Neuritis and colour vision reduction
Yes!
Can you give BCG to HIV positive individuals?
No!
CMV
what is the risk to baby if it is mums first infection
What stage of pregnancy is it worst to contract it?
What are the features
What is seen in ultrasound
50%
Worst in the first half of preg.
IUGR, blueberry muffin rash, chorioretinitis , SN hearing loss
Periventricular calcification
Zika
What type of virus is it
How does it present
What is different on head ultrasound
Flavivirus
Microcephalic, contractures, hypotonia and irritable
Subcritical calcification
Congenital syphillis
What is it associated with
How does it present in the newborn
If it is missed how might it present
Lacking antenatal care
Sniffles, peeling skin, pseudopariesis, jaundice and hepatosplenomegaly
Abnormal teeth and facial deformities. Blindness
Toxoplasmosis
When is it most likely to affect the baby?
How does it present?
3rd trimester
Asymptomatic or prolonged jaundice then blindness seizures and developmental delay
What is the most common cause of eosinophilic meningitis?
What is usually ingested?
What will you see on LP?
How is it managed?
Angiostrongylus
Snails
High opening pressure, high cell count, eosinophils >10%
Analgesia, therapeutic taps and steroids
What is the most common helminithic infection in humans
Ascariasis=roundworms
What is the other name for a pinworm infection
How do they present
How are they found
Enterobius vermicularis
Itchy bums
Cellotape test
Which helminithic infectionis seen in travellers
What rash do they commonly get?
Hookworm-ancylostoma
Itchy rash in the soles of the feet that moves around
Which helminithic infection is involved in sheep stations
Echinococcous
Viruses
How do dna and rna viruses differ in how they replicate
What enzyme do retroviruses use to replicate
DNA- use the cells nucleus
RNA- replicate within the cytoplasm
Herpes
Where to the 2 main types cause lesions
1- mouth
2-genitals
Where does the herpes virus lie dormant
What infection indicates reactivation
Sensory ganglion neurons
Cold sores
What are 3 skin manifestations of herpes?
Herpetic whitlow
Eczema herpeticum
Erythema multiforme
How does intrauterine herpes present
Microcephalic, vesicles and chorioretinitis
What does HHV 6 cause
How does it present?
Rosella
High fever
Blanching rash
What does HHV 8 cause?
Kaposis sarcoma
Varicella
What does primary infection cause
What is most likely to cause a secondary bacterial infection
What does involvement of the tip of the nose suggest
Chicken pox
Strep pyogenes
Hutchinsons sign- corneal involvement
Varicella-
Where is encephalitis likely to involve
What is the more likely CNS manifestation of varicella
Temporal lobes
Cerebellar ataxia
How does congenital varicella present
IUGR
Scarring
Limb shortening
Chorioretinitis
What percentage of people seroconvert to the varicella vaccine
97%
Poliovirus
What is the most common clinical manifestation?
What else can it cause
Slapped cheek (fifth disease) Acute aplastic crises
Adenoviruses
How do they most likely present
Resp infections
Enteroviruses
What family of viruses are they
What is the most likely presentation
RNA viruses
Non specific viral illnesses
Enteroviruses
What causes hand foot and mouth most commonly? What might give cns disease
What causes herpangina
Coxsackie A. Enterovirus 71
Coxsackie A
Enteroviruses
Give 4 CNS manifestations
What 3 types of enteroviruses might cause them
Polio, flaccid paralysis, aseptic meningitis, encephalitis
Polio, echo, coxsackie B
What type of enterovirus causes myocarditis
Who is most likely to get it?
Coxsackie B
Young adolescent males
CMV
What family of viruses does it belong to?
What four things is it the commonest cause of
Herpes
CP, SN hearing loss, Low IQ and congenital infections
CMV
How do the majority of primary infections present?
How else might they present?
If you are immunocompromised how might you present?
How might it affect transplants
Asymptomatic
Mono like but no sore throat
Unwell with fevers and joint pains. Pneumonitis and GI disease
Causes rejection.
CMV
How do perinatal and congenital infections differ?
What is seen on head uss
Perinatal- majority are still asymptomatic
Congenital- iugr, chorioretinitis, late onset hearing loss, jaundice and seizures
Periventricular calcification
How do CMV and HIV link?
CMV increases rate of HIV progression
More likely to get retinitis and cns side effects
Congenital CMV
Is there firm evidence for treatment? What might be used
No!
Ganciclovir
EBV
What type of virus is it?
What can reactivate it?
What malignancies is it associated with?
DNA virus
Immunosuppression
Burkitts, Hodgkin lymphoma, NP carcinoma and gastric carcinoma
Infectious mono
How does it present
What signs might there be?
What can give a diffuse maculopapular rash
Fever sore throat and lethargy
Palatal petechiae, lymphadenopathy and hepatosplenomegaly
Amoxicillin
EBV
Give 4 complications of acute infection
Splenic rupture
Airway obstruction
Myocarditis
GBS
EBV
What things can have a severe disseminated reaction?
CVID/AT/CH/WA
X linked lymphoproliferative syndrome
HIV
EBV
What is seen on blood film
Atypical mononuclear cells
EBV
What antibodies are positive in acute and chronic infection
VCAs early
EBNAs later
HIV
What type of cells does it infect
What enzyme is important
CD4 cells
Reverse transcriptase
HIV
How might an acute infection present
What might be seen on bloods to show progress of hiv
What is most predictive of rate of progress
What is most predictive of complication risks
Lymphadenopathy, flu like illness
T cell depletion, increasing viral load
Viral load
CD 4 counts
What level of T cells causes AIDS
What are examples of aids defining illnesses (6)
What sign in children is unique to HIV
<200 Kaposis sarcoma PCP pneumonia Chronic oesophageal candidiasis Lymphocytic interstitial pneumonia CMV pneumonitis or retinitis Mycobacterium avium HIV encephalopathy
Chronic or recurrent parotitis
Why is combination treatment used in AIDS
What is the aim
To prevent resistance
To reduce and slow progression of disease
HIV
what 3 drug classes are most commonly used? Give examples
What other 2 drug classes might be used
Nucleoside reverse transcriptase inhibitors- lamudivine, zidovudine
Protease inhibitor nelfinar
Non nucleoside RTIs
Fusion inhibitors
What 2 large groups of conditions does a group A strep cause
What are the common complications
How are they treated
Are they resistant?
Pharyngitis and skin infections
HUS, rheumatic fever, PANDAS, reactive arthritis
Penicillin
Usually never!
What causes group A strep to turn into scarlet fever
How does scarlet fever present
Production of strep pyogenes erythrogenic exotoxin
Sore throat then strawberry tongue and sandpaper rash
Group B strep
What is it called
What is the most likely cause of infection?
What are the 2 different presentations and how do they present
How is it treated
How long is treatment- bacteraemia? Meningitis?
Agalactiae
Maternal colonisation
Early onset sepsis- very sick like RDS. Can be still born
Late sepsis- up to 3 months. Occult bacteraemia or meningitis
High dose amoxicillin or penicillin.
Bacteraemia-10 d Meningitis-14 d
Strep pneumoniae
How does it link to influenza
How is it treated
What does an intermediate mic to penicillin suggest? What is given instead?
Causes secondary bacterial pneumonias
Penicillin
Possible cephalosporin resistance- vanc instead
Listeria
In older children what might infection suggest
How does late and early disease differ
What is it resistant to
T cell issues Late- more likely meningitis Early- vague with maculopapular rash. Might have had a sick fluey mum Prem babies with MEC stained liquor Cephalosporins
Coagulase negative staph
Give 2 examples
What do they cause
Are they sensitive to penicillins?
Staph epidermidis and staph saphrophyticus
Line infections!
No!
Staph Aureus
Give two ways it can become a MRSA
How does it cause diseases like toxic shock syndromes
Altered penicillin binding proteins
Beta lactamase
Production of exotoxins
What antibiotic is pseudomonas intrinsically resistant to?
What colour of pus does it cause
Cefuroxime
Blue/green
What type of diarrhoea is seen in cryptosporidium
Secretory
What is seen on microscopy with giardia?
Multi flagellated organism
What is klebsiella an example of?
What is it therefore resistant to?
ESBL
Resistant to carbapenems
What is an example of a VRE
E faecum
What mnemonic helps remember resistant organisms
E-enterococcus (VRE) S-staph aureus (MRSA) K- klebsiella (ESBL) A- acinetobacter P-pseudomonas E- enterobacter
What might help differentiate strep from staph toxic shock?
Septicaemia
Measles
How well does it seroconvert after a vaccine? After 2?
Does infection provide life long immunity?
If you are exposed and your immunity is ok how should you be treated
If you’re exposed and you’re immunodeficient how should you be treated?
95% 99%
Yes
Give vaccine within 72 hrs
Give IVIG within 1 week
What is the most common cause of bacterial tracheitis
Staph aureus
Which antibacterial agents disrupt cell membrane function
Anti fungals
Which 3 groups of antibiotics inhibit cell wall synthesis
How do they do this
What 3 days can resistance occur- give examples of bugs
Are they bacteriostatic or bacteriocidal?
Penicillins, cephalosporins and carbapenems
Insert a beta lactam ring into the cell membrane
Staph aureus- makes a beta lactamase
MRSA and pneumococcus- alter penicillin binding proteins
Pseudomonas- reduces cell wall permeability
Bacteriocidal
Which 2 antibiotics inhibit folate synthesis
What is a way to remember this
Co trimoxazole
Trimethoprim
Both used for UTIs- think pregnancy and folate!
Which antibiotic inhibits DNA gyrase
Ciprofloxacin (quinolones)
How does vancomycin work
What pharmacokinetic parameters are most important
What part of the dosing is most important
Acts directly on the cell wall
AUC/MIC
Peak concentration
Beta lactatams
Which pharmacokinetic parameter is most important
What about the dosing therefore is most important
Time above MIC
Dosing interval
Give 2 examples of antibiotics that act on the 30s subunit
Gentamicin
Doxycycline
Give 3 examples of antibiotics that act on the 50s subunit
Macrolides
Clindamycin
Chloramphenicol
What pharmacokinetic parameter is most important in amino glycosides
What therefore in dosing is most important
Cmax/MIC
Peak concentration
What pharmacokinetic profile suggests resistance
MBC >4x MIC
Cephalosporins Give examples of the 5 generations What do generation 1-3 treat well What is good about generation 3 What dose generation 4 treat What does generation 5 treat
1- cephalexin 2- cefuroxime 3- cefotaxime and cefreiaxone 4- cefepime 5- ceftaroline
1-3 improving gram negative cover, gradually lose gram positive
3- blood brain barrier cover
4- pseudomonas
5- MRSA
What do cephalosporins not cover?
Listeria
Atypical (mycoplasma and chlamydia)
MRSA (unless 5th gen)
Enterococcus
What organisms rarely can be resistant to carbapenems
What antibiotics have to be used instead
Klebsiella and E. coli (new deli metallo beta lactams)
Coloistin or fosfamycin
What does vancymicin cover well
Gram positives and MRSA
If vanc does not work well for MRSA what is another good option
Linezolid
What do aminoglycosides cover well?
What is an example of a bug it won’t cover well
Gram negatives
Enterococcus
What do macrolides cover well- give 2 examples
Atypical
Mycoplasma and gonorrhoea
Why are macrolides useful in CF
Modulate airway inflammation
How effective is the pertussis vaccine if three doses are given
95%
Can pertussis cause retinal haemorrhages?
No!! (New evidence)
Pneumococcus
What type of organism is it
To use penicillin what is needed. If not what is used to treat
Encapsulated
High MIC needed- <0.6. Otherwise 3rd gen cephalosporins
How are staph further characterised?
Coagulase- positive- epi negative- aureus
What are enterococcus
How are they normally treated. What are they normally resistant to?
How is e cloacae treated
How is VRE treated? Is it bacteriocidal or bacteriostatic? What will this not be useful for?
HOW IS CPE treated
Strep with no haemolysis Amoxicillin Cephalosporins Meropenem Linezolid. Cloacae Tigecycline
How long before and after the rash are the following infectious?
Measles
Chicken pox
Measles- 3D before 5-6 after
Chicken pox- 24-48 hrs before, 3-7days after
What is aspergillosis usually resistant to?
What is It therefore treated with
What are most species of candida sensitive to
Fluconazole
Voriconazole
Amphotericin B
What are three vaccines that can’t be frozen
Hep A and B
DTAp
Tetanus
How does rubella normally present
When is it infectious
What can happen especially in girls
What is it otherwise known as
Painful lymphadenopathy with rash
5 days before and after rash
Arthritis
3 day measles
What are 2 examples of an inactivated vaccine Attenuated Toxoid Subunit Conjugate
Influenza and polio MMR and TB Diphtheria and tetanus HPV and hep B Hib
What can adenovirus cause
Haemorrhaging cystitis
