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what is the magnification of oil stained microscopy?
how to describe the ZN staining with TB?
- blue background
- pink staining - single and clumps
- acid fast bacilli
what is first line Rx for TB?
- 4 drugs for 2 months: RIPE
- 2 drugs for 4 months: RI
how do you define MDR TB?
resistance to at least rifampicin and isoniazid
can you explain open TB
- sputum smear positive is better term
- one of the infected alveoli has burst into major bronchus and he is now expectorating sputum with AFB in it - transmissible organisms to other people
when do you admit someone for TB?
- problems with drug compliance
- respiratory problems
- other medical problems
- not if fit and well as long as agree to take drugs and self isolate at home
if you admit a TB pt, what do u have to arrange?
- respiratory isolation facility
- negative pressure: is air is sucked into that room so other people on ward don't get the air he breathes out
what do you advise about self isolation?
- as it has insidious history - been coughing all over certain people
- don't need to lock him away
- but entire family need to attend clinic, investigated and given prophylaxis
how do you manage the patients family?
if had BCG: chest x-ray, if symptoms report them
how do you do a mantoux test?
- inject PPD - proteinacious antigen of M Tb intradermally then mark the area and check it 48 hours later
- look for cell mediated/delayed hypersensitivity reaction to a T cell mediated cellular reaction
- measure the induration in mm
how do you assess mantoux response?
- up to 10mm reaction to BCG
- >10-12 mm is graded
- >15mm hugely positive
what investigation would you do on the children of a patient with TB?
- may not do CXR as they have thymus there and radiation
- may do mantoux test
if mantoux is normal and significant contact with TB patient what to do?
- Isoniazid & Rifampicin for 3 months
- or Isoniazid alone for 6 months
pt comes to you and is really feeling better after 1 month of Rx what do you do?
- do not stop
- have to complete course
- primary drivers for resistance is incomplete or non-compliant
is TB vaccine still given in UK?
- not routinely
- only to high risk individuals
- at birth
- individuals who are recent migrants from endemic high risk areas
- eg whitechapel Bangladeshi
- or family history of contact with TB
what is the principle for INF gamma release assay (IGRA)?
- replacing or adjunct to mantoux
- principle: draw blood,
- seclude T cells from sample,
- challenge with TB antigens,
- T cells get excited and release more than baseline interferon
what is the big advantage of IGRA?
- isolated Ag that stimulates patients T cells as being different form the one used for BCG (ie wont cross react with BCG)!
- so mantoux is confounded by having had BCG, IGRA is not confounded
how protected is the BCG vaccine?
- certain areas of the world not protective against post-primary pulm TB
- eg Africa, india - but WHO says still give vaccine as some protection for serious TB eg TB meningitis
- 70% protection in UK
- reactions with other environmental mycobacteria, temperature of keeping BCG
what is the main aim of BCG vaccine?
protect from TB meningitis
how do you describe erysipelas?
- hard indurated lesion on face
- clearly demarcated
- raised edge
- peripheral fluid blistering formation
what organisms cause erysipelas?
- GAS - strep progenies (beta haemolytic - complete haemolysis on blood agar)
how is erysipelas different to cellulitis? in term of location and progression?
- more SUPERFICIAL infection
- affects: epidermis and dermis
- progression: more rapid than celulitis
name 2 toxin associated syndromes with this organism?
- scarlet fever - erythrogenic toxin
- toxic shock syndrome
why would people with erysipelas feel unwell and vomit?
what Ix do you do in suspected erysipelas?
- blood cultures
- ASOT = serology (anti streptolysin O titre)
- skin swabs unhelpful generally
what is Rx of erysipelas? how do you tailor to pt?
- oral if well
- if systemically unwell need iv benzyl penicllin
what is Rx of erysipelas if pen allergic?
- clindamycin or clarythromycin
- oral is ok
2 life threatening syndromes associated with GAS?
- necrotising fasciitis
- puerperal fever - post partum - single most important RF is c-section
if the Ix is electron microscopy what type of organism does it suggest?
what does rotavirus look like?
spokes of a wheel in outer rim of virus
what are classic symptoms of rotavirus
- age group
- no blood as non invasive
- these are classic triad of viral diarrhoea
if you do not treat rotavirus, what would happen?
- renal failure - acute tubular necrosis
what is commonest mode of transmission of rotavirus?
what is associated with outbreaks
creche, nursery, COTE homes - all suddenly incontinent of faeces
what is a carbuncle?
- abscess larger than a boil (collection of abscesses due to failure to control)
- usually has openings draining pus onto skin
who gets carbuncles?
- weak immunity
- diabetes, HIV
what is usual cause of carbuncle?
what is most common location of carbuncle?
name 3 toxin assoc conditions
- scalded skin syndrome - skin damage, blisters, skin sheds (more in infants <5)
- PVL - panton valentine leukocidin: cytotoxin destroy WBC, necrosis severe infection
- Toxic shock syndrome
- food poisoning - enterotoxin
what is Rx of carbuncle?
- clindamycin if pen allergic
- if very unwell: iv glycopeptide
if MRSA and doesn't tolerate glycopeptide what to give?
linezolid - very well orally absorbed
pt is about to have hip operation and has nose screen for MRSA. how to explain?
- common carriage sites for MRSA and easily accessible
- lots of people carry MRSA on skin and nose(10-20%)
- if having invasive at risk procedure - at risk of prosthesis and procedure becoming infected with MRSA
- we want to minimise risk before start operation
what to do if nose swab is MRSA+?
- suprression regimen
- chlorhexidine bath and shampoo for 5 days
- nasal ointment with mupirocin
once suppression regimen is done what to do?
- operation 2-3days after regimen
- don't need to rescreen
what other precautions take if nose MRSA+?
- prophylactic against MRSA peri-operatively iv glycopeptide
- done under laminar flow
- strict attention to skin asepsis
- check signs for infection: febrile unable to weight bear, high WBC, rising CRP
if prosthesis gets infected what to do?
deal with superficial infection so doesn't get deep seated
what are side effects of vancomycin and how monitor?
- measure levels as renally excreted
why would you use a MacConkey agar plate?
- G-ve organisms - UTI
- if go pink they are the fermenters
- if stay yellow - non fermenters
what is it called when a pregnant lady has >10x5 cfu of e coli in urine but she feels fine?
do you treat asymptomatic bacteria?
- yes in pregnancy
- risk of ascending infection
- causing pyelonephritis
- bladder urine is sterile
why do MSU?
- allow first part of stream to wash off normal flora
- catch middle stream which should be sterile
- transport to lab asap
why do we treat asymptomatic bacteuria in pregnancy?
- whenever stasis of urine - culture medium
- 1. in pregnancy get incomplete emptying of urine in bladder because of pressure of fetal head
- 2. back pressure of urine pushes urine up ureter into kidney
- 3. progesterone - musculature in valves is lax - so high risk up ureter and into renal pelvis - pyelonephritis
why is pyelonephritis such a worry in pregnancy?
- high fever can precipitate pre-term labour
- Low birth, maternal sepsis, pre term labour
name 2 antibiotics to Rx UTI in pregnancy?
- send urine for MC&S to make sure
2 abx to avoid in pregnancy for treating UTI and why?
- trimethroprim in early pregnant: folic acid inhibition (can give in early)
- ciprofloxacin (if have to - talk with obstetrician)
- nitrofurantoin: not in late pregnancy as causes neonatal haemolysis
what is risk with trimethoprim in pregnancy?
folic acid inhibition in early pregnancy
what is risk with nitrofurantoin in pregnancy?
neonatal haemolysis in late pregnancy
what is treatment of GE diarrhoea generally?
- shouldn't give abx unless systemically unwell
what is Rx for campylobacter infection?
- erythromycin not cipro
- as cipro is used in chickenfeed so campylo is resistant to it
what does campylobacter look like on gram stain?
- gram -ve
- seagull shaped/curved
how do you investigate suspected C-diff diarrhoea?
stool sample for C-diff toxin and routine culture in case other cause
how to treat c-diff diarrhoea? and what is overall management?
- stop antibiotic
- start metronidazole oral
- or oral vancomycin
- if nil by mouth which abx iv metronidazole (not vanc as poorly absorbed into gut where we need it)
- source isolate in a side room
- attention to hand washing
- gloves and aprons to deal with pt
- take off gloves and aprons inside room and wash hands with soap and water not alcohol gel
if patient has renal problems and suspect c-diff would you be worried about giving vancomycin and why?
- not worried
- oral vancomycin
- not systemically absorbed so not worried about renal failure
- don't need to measure levels
OSCE how did i get this infection in my heart?
- organism enter bloodstream from poor dentition or other lesion
- siting on damaged heart valve (rheumatic fever)
- causeing IE
how ascertain IE?
echo visualise lesion
Rx of IE?
ben pen and gentamicin
how long stay in hospital
- MIC of organism
- how susceptible organism is to penicillin and we will work out regimen
- be prepared at least 4 weeks of iv treatment
gentamicin toxic drug
- reassure: make sure levels in safe therapeutic margin by titrating dose appropriately according to levels
if allergic to penicillin which drug in IE?
vancomycin or teicoplanin
what are indications of vancomycin in IE?
- allergic to penicliln
- MRSA IE
- CNS endocarditis in prosthetic valve
need prophylaxis for dental procedures if had past IE?
completely perfect set of teeth don't need to prophylaxis
what is most common cause of UTI?
what does e coli look like on gram stain?
what would you detect on urine dipstick of UTI?
- leucocyte esterase - shows there are leucocytes there
- nitrites - e coli reduces nitrates to nitrites
how to treat community UTI?
trimethroprim or nitrofurantoin 3 days
if you see organism was cultured in McCoy cell line and has inclusion bodies on culture what organism likely?
chlamydia as intracellular
how to treat chlamydia conjunctivitis in 10day baby?
- erythromycin or azithromycin iv as risk of pneumonia in baby
- wash eye with sterile saline
- not tetracycline as cant give to children - yellow/grey staining of teeth
what could you mistake G+ve cocci on gram stain for? how differentiate?
- see budding of yeast cells - daughter cell bud from mother
what are risk factors of candida infection?
- broad spectrum antibiotic
how do you treat candida pyelonephritis? how long?
- iv fluconazole 2 weeks at least
- repeat urinalysis
- monitor with US too
OSCE chickenpox: pregnant mother with other child with chickenpox. can i take child to ANC?
- no as other women there susceptible
- have you had chickenpox?
- child had 4days of illness, can mother go today?
- can if today as not infectious yet - can go up to day 8
- cannot go if > 8 days until 21 days from start of illness
what is the incubation period of VZV?
what is the infectious period of VZV?
2 days before rash until it is fully scabbed over
what is main cause of osteomyelitis?
what is empirical treatment of osteomyelitis?
- 2 weeks iv flucloxacillin
- 4 weeks oral flucloxacillin
- oral fusidic acid 6 weeks
what would you see on XR of osteomyelitis?
periosteal elevation of affected bone
name 4 organisms causing nosocomial pneumonia in ventilated patients?
what is likely source of ventilator assoc pneum organisms?
endogenous - gut
name 4 anti psuedomonal traetment?
- ciprofloxacin (but not good for lung)
what is empirical Rx for 1 yr old boy who has fever and vomiting and positive urine culture?
- ceftriaxone iv
- to cover UTI and meningitis
what can happen if recurrent UTI in children is not treated?
reflux - acute pyelonephritis and scarring
which abx use for pseudomonas UTI?
- only oral anti pseudomonal