Micro Sem 2 Flashcards
2 most common causes of meningitis in neonates and premature births. give bacterial origins
E coli (gut) and Group B Strep (vagina).
2 most common viruses that cause meningitis
Enterovirus and HSV
in a case of suspected viral meningitis, if CSF was unavailable would the isolation of a virus from another specimen be significant?
The sample MUST be from CSF to confirm. Isolation from another specimen not necessarily associated with meningitis
what are the 3 main causes of bacterial meningitis? which can be prevented by vaccine
strep Pneumonia, Nisserium Meningitides & H. Influenzae type B.Strep and Hib have vaccine
how do you treat meningitis in premature birth?
give mother penicillin 4 hours before birth
how do you treat viral meningitis?
self limiting so supportive therapy
meningital symptoms with a petechial rash point to which causitive agent?
N. meningitidis
hallmark of CSF in bacterial menigitis
turbid CSF, low glucose high protein
why and in what circumstances would you want to innoculate CSF in a serum broth
to make any surviving bacteria grow in a case where anti-biotic was used before csf was taken
how should treat patients contacts in cases of meningitis
prophylactic antibiotics or vaccinate
why would you admit someone to hospital overnight in an allergic reaction (nut) despite improvement
due to a potential delayed inflammatory response by cytokines and eosinophils
why should one wait to perform an allergen test after someone’s first allergic reaction?
mast cells need to regenerate
what is impetigo? how is it transmitted and what is most likely cause?
‘school sores’ is a highly contagious bacterial skin infection usually caused by Staph. A. It is common amongst young children and people who play close contact sport
main symptoms for rheumatic fever and what causes it?
high fever, carditis (murmur) and polyarthritis. It occurs following a Strep P infection
describe the pathology of symptoms in rheumatic fever
auto-immune response damages the heart and joints. Type II hypersensitivity involving the M protein in heart (molecular mimicry)
what is the gold standard for diagnosing coeliac
jejunal biopsy
associated features with coeliac?
infertility, delayed puberty, anaemia, osteoporosis
butterfly rash on nose is typical of what
lupus
explain pathology of SLE
type III hypersensitivity. Immune complexes are systemic originally. Symptoms occur when they begin to deposit
what can cause onset of SLE
sunburn and cell death
what are some clinical manifestation of SLE
depends where the immune complexes deposit. Skin = Rash. Lungs = Pleurisy. Kidney = nephritis. CNS
patient comes in with polyarthritis. Says has infection 2 weeks ago. Doctor did ANA and rheumatoid factor test. What are these for?
ANA (for SLE) and Rheumatoid factor (for rheumatoid arthritis)
bacteria that can cause post infective arthritis?
salmonella, campylobacter, yersinia and STIs
how is yersinia infection acquired?
environmental organism - associated with farmed animals and milk
explain lifecycle of hookworm
walking barefoot >worm bites foot > enters blood > goes to respiratory tract > is swallowed then adults mature in gut
why may someone with hookworms be anaemic?
blood loss associated with the way the worms attach to the intestine
explain pathogensis and life cycle of roundworms
faecal-oral. Ingest eggs > hatch and invade intestinal mucosa > get into blood
PUO in a recently returned traveller?
malaria until prove otherwise. can be rapidly fatal
which is the dangerous form of malaria? why?
P. Falciparin. Can infect all stages of the RBC life cycle. Can have multiple parasties per RBC. RBCs get nodules so potential to clot
how does P Vivax infect?
mozzie bite > latent in liver
life cycle of strongoloides
Almost identical to hookworm.Larva enter through feet > blood > lungs > swallow > mature in gut > lay eggs > hatch rapidly so can find eggs in faeces
a patient who fought in Nam in 1970s was recently diagnosed with leukaemia. He also only now presents with parasitic symptoms. why?
immunosupressed. would have had parasite since the 70s
which bacteria causes typhoid fever? explain pathogenisis
salmonella typhi.Faecal-oral ingestion. Replicate in gut > carried by macrophages to lymphs > get into blood > sceptacaemia
itching coupled with white vaginal discharge that is clumped (cottage cheese) is a sign of what? what is responsible for infection? treatment?
candidiasis(thrush). Candida albicans. treat with candicidin or nystatin
in the context of STI’s gram negative diplococci ingested by cells is a sign of what?
clamydia
what 2 STIs are commonly found together? treatmemt?
Gonorrhea + clamydia. treat with ceftriaxone and azythromycin
mild fever, malaise, anorexia and nausea. yellow eyes and tender, enlarged liver. no IV drug use. new male-male sex partner. likely diagnosis
Hep B
what is hallmark in Hep B diagnostic and WHO definition
presence of surface antigen (HBs Ag) indicates current infection.
what do positice Anti HBs, HBe Ag, Anti HBe, Anti HBc IgM and Anti HBc IgG as refer to in regard to hepatitis testing? a
Anti HBs = cleared infection and have immunity.HBe Ag = active (replicating infection).Anti HBe = not active (not replicating).Anti HBc IgM = antibodies to core. have disease, likely recent.Anti HBc IgG = Antibodies to core, chronic infection
painful blisters on and around vagina. possible diagnosis?
HSV 2
how does one acquire HSV. where does it survive latently?
From another person (kissing, sex). can be latent for years or decades in dorsal root ganglion.
what factors can exacerbate HSV (4)?
cold, stress, UV light, immunosupression
consequences of infection with HSV?
can be symptomatic or asymptomatic. Can be transmitted during pregnancy which is a problem
treatment of HSV?
acyclovir - wont remove virus but will suppress symptoms
diffuse erythematous maculopapular rash. possible infections (2)?
ruebella, parvo-virus.
if checking for a specific virus why would you measure both IgM and IgG
to distinguish b/w recent or past infection.
limitations in testing for specific antibodies of IgM?
if positive dont know how long IgM has been around for
outcomes for parvo-virus in pregancy?
will normally terminate the pregnancy
other name for parvo-virus
erythrovirus
outcomes for rubella during pregnancy?
depends on age of infection. the earlier the infection the worse the outcome.1/3 live normally, 1/3 live with parents, 1/3 institutionalised
clinical signs of ruebella?
maculopapular rash, lymphadenopathy, low grade fever, polyarthritis
Congenital rubella syndrome classic presentation
Ear (deafness), eye (cataracts or retinopathy) and cardio (patent ductus arteriosis or pulmonary artery stenosis)
FBE showed significant leucocytosis (49% lymphocytes). some atypical mononuclear cells were seen. lab thought it was virus. Give 3 potential infectious agents.
CMV, EBV, HIV
what is the normal proportion of lymphocytes witihn leukocytes?
20%
what do atypical mononuulear cells mean?
activated CD8 T cells
What does EBV do to immune system? how do we test for it?
make B cells spit out whatever antibody they are programmed to. This includes the AB for sheep’s blood which is what we test for (Monodpot test).
what is possible outcomes of infections with CMV.
commonly acquired by late adulthood (60s). Most will never know they have it and will be asymptomaatic
possible outcomes of CMV when pregnant?
10% of babies that get CMV will have long term sequalae
what should be the management of a pregant person with CMV
nothing in utero. monitor baby when born and try to control it spreading the virus
apart from endocarditis where else can Staph E. commonly cause infection?
intravenous catheters and on medical prostheses
which organism associated with water?
P. Aeroginosa
what type of bacteria is P. Aeroginosa? what color does it grow on MAC?
GNR. grows green
centrimide agar is selective for what?
pseudomonas
would the presence of P. Aeroginosa on supposedly sterile endoscopes pose a threat?
depends on what doing with endoscope. If using in a sterile site (eg brain) is a problem.In a non sterile site(eg colonoscopy) not too much of a problem
what is the susceptibility of P. Aeroginosa to antibiotics?
extremely resistant
what 4 pieces of information are needed to design an appropriate sterilisation process for a particular instrument?
- type and amount of contamination2. Death rate of organism3. Level of sterility assurance required4. will the instrument survive the process
Three days after undergoing coronary artery by-pass surgery, S.J., a 58-year-old man, developed a fever (38.5°C).Clinical examination was normal except for mild tachycardia and the finding that the operation scar showed some surrounding redness and a discharge of some blood stained fluid.The patient was treated with fiucloxacillin and his operation site was cleaned. His symptoms settled, and he was discharged after 10 days.During the next three weeks at home, however, he lost weight and developed a fever and malaise so that he was readmitted to hospital 21 days after his original discharge. On examination his surgical wound appeared normal and had healed well. A soft diastolic murmur was heard on auscultation. Diagnosis?
sub-acute endocarditis as progressed slowly over weeks.
Mrs. EW, a 67-year-old woman with rheumatic heart disease was admitted to hospital for mitral valve replacement together with a coronary artery bypass graft. Three days after her operation, she was found to have a fever (39.8°C), and her respiratory rate was 36/min. she was diagnosed with lobar pneumonia. She was commenced on cefotaxime, however, 48 hours later, when the results of the laboratory investigations suggested that the cause of her infection was Klebsiella pneumoniae, a decision was made to change to IV gentamicin. The patient’s fever dropped and her respiratory symptoms slowly improved over the next few days. 5 days after the onset of pneumonia, Mrs. EW awoke with a low grade fever. She complained of cramping abdominal pain, and passed several watery, foul-smelling stools.Diagnosis and what has caused this?
C. Difficile - it is part of normal microbiota but the antibiotics killed the many of the regular microbiota and resulting in overgrowth
in the C. Difficile case what pathogens wouldve been screened for in routine faeces sample (5)
EHEC, camplyobacter, salmonella, yersinia, shigella
what type of condition does C difficile need?
strict anaerobe
how is C difficile transmitted?
fecal-oral route. the organism forms spores that are not killed by alcohol-based hand cleansers or routine surface cleaning.
most common virus transmitted in solid organ transplant
CMV
how can CMV infection be prevent in organ transplant?
prophylactic antivirals (gangcyclovir)
how should CMV be treat if infectious? result?
anti-viral (gangcyclovir) will suppress disease but not cure
what questions should a GP ask if patient comes positive for hep C? (3)
IV drug use, blood contacts, past surgeries
consequences of not treating hep c?
70-80% likelihood of becoming chronic carrier
how can Hep C be treated (name the drug types). results?
RNA polymerase inhibitors and protease inhibitors. No side effects and will clear virus
type of bacteria is chlamydia? where (cellularly) does it reside? what is significant about staining?
gram neg with no cell wall, obligate intracelullar parasite so cant see on staining
2 forms of chlamydia? whats the dif? which can be treated?
i) elementary body (EB, 0.2 μm) - infectious, nonreplicating, hardy. ii) reticulate body (RB, 0.8 μm) – intracellular,replicating form.Can treat the RB with antibiotics.
