Common Infections/UTI/Cellulitis Flashcards
What are the features of inflammation?
inflammation
- pain = dolor
- redness = rubor
- swelling = tumor
- heat = calor
- loss of function
What are the types of UTI?
uncomplicated UTI - infection in a structurally and/or functionally normal urinary tract in non-pregnant women
complicated UTI - infection in a structurally and/or functionally abnormal urinary tract, post urological surgery, pyelonephritis, children, pregnancy
catheter associated UTI - have similar symptoms to complicated/uncomplicated UTIs but different causes therefore different treatment
recurrent UTI - defined as two separate culture proven episodes of acute UTIs and associated symptoms within 6 months or >3 UTIs in 12 months
Where are lower and upper UTIs located?
UTI can affect anywhere in the urinary tract
- upper UTIs are more severe than lower UTIs
urethra - urethritis = lower UTI
bladder - cystitis = lower UTI
ureter - urethritis = upper UTI
kidneys - pyelonephritis = upper UTI
What are the causative pathogens of UTIs? Which are the most common causes?
gram negative (most found in the GIT)
- E.coli = most common cause
- proteus spp
- klebsiella sp
- pseudomonas aeruginosa (most common cause in catheter associated UTIs)
gram positive (most found on the surface of the body/skin)
- enterococci spp
- staph saprophyticus
anaerobes
gram negative > gram positive
What are the risk factors for UTIs?
menopause - due to reduced levels of oestrogen
sexual activity
catheters - are a route of entry for bacteria
blockage of urinary tract - allows residual volume of urine to accumulate and act as a bacterial reservoir
weakened immune system
diabetes - more prone due to poor circulation, high glucose level, poor bladder emptying
pregnancy - due to changes in urinary tract
elderly - due to weakened bladder
What are the signs and symptoms of UTI?
cloudy urine
dysuria - pain upon urination
urinary urge or frequency
haematuria - blood in urine
polyuria
malaise
fever
confusion or agitation = especially in older people
foul/strong smelling urine
pelvic pain
What are the symptoms of pyelonephritis?
fever - temperature > 37.9 and rigours (shaking/chills)
flank pain - pain in the back, over the kidneys
nausea and/or vomiting
How can patients be tested for UTIs?
urine dip stick
- detect presence of bacteria
- changes colour if urine contains the following substances above normal range
= leukocytes (bacterial infection, sign of WBCs), nitrites (gram negative bacteria), haemoglobin (blood in urine)
- can check the pH of unrine
visual look
- cloudy or smelly urine
mid stream urine sample
- detect presence of bacteria
- allows urine to flush out ureteral contaminant
- preferably done in the mornings when bacterial count is higher
ultrasound, computerised tomography (CT) scan or magnetic resonance imaging (MRI)
- for recurrent UTIs suggesting urinary tract abnormality
urine culture
- detect cause of bacterial infection
When should a urine dipstick not be performed?
urine dipsticks should not be performed on people aged >65 years old
- due to increased vulnerability
What is the treatment for uncomplicated UTIs?
women
uncomplicated UTIs
- non-pregnant women = 3 day treatment
first line
- nitrofurantoin MR 100mg twice a day
= avoid if eGFR < 45ml/min
= avoid if close to birth/at term = increased risk of miscarriage
- trimethoprim 200 mg twice a day
= if risk of resistance is low
second line
- pivmecillinam 400mg initial dose then 200mg three times a day
What is the treatment for uncomplicated UTIs?
men
uncomplicated UTIs
- men = 7 days
first line
- trimethoprim 200mg twice a day
- nitrofurantoin MR 100mg twice a day
= avoid if eGFR < 45ml/min
What is the treatment for complicated UTI?
pregnant women
complicated UTIs
- pregnant women = 7 days
first line
- nitrofurantoin MR 100mg twice a day
= avoid if eGFR < 45ml/min
= avoid if close to birth/at term = increased risk of miscarriage
second line
- amoxicillin 500 mg three times a day
= only if culture results are available and susceptible
- cefalexin 500 mg twice a day
What UTI treatment should be avoided in pregnant women and why?
trimethoprim should be avoided
- has teratogenic risk
= is a folate antagonist
Why should pregnant women always be treated for UTIs even if asymptomatic?
due to risk of
- premature labour
- pyelonephritis
- developmental delay in foetus
- foetal death
What is cellulitis?
What is the difference between cellulitis, erysipelas and abscess?
acute infection of the skin and subcutaneous tissue
- develops suddenly and spreads quickly
cellulitis - affect deeper dermis and subcutaneous fat
erysipelas - affects epidermis/upper dermis
abscess - affects dermis and subcutaneous space/tissue, is a collection of pus
What are the causative pathogens of cellulitis?
gram positive (most found on the skin surface and are the most common cause)
- staphylococcus aureus
- beta haemolytic: streptococcus (Groups A, C and G)
gram negative (rarely cause)
- pseudomonas aeruginosa
diabetics or vascular insufficiency
- gram positive
- anaerobes = Clostridium sp
What are the risk factors for cellulitis?
poor circulation
oedema
peripheral vascular disease
diabetes
fungal skin infection
recent vaccination
obesity
immunosuppression
What are the signs and symptoms of cellulitis? How can it be diagnosed?
acute inflammation
- swelling, pain, redness, heat, loss of function
spreading erythema (redness)
systemic symptoms
- fever, tachycardia, hypotension
diagnosis
- skin swabs (if skin is broken), blood cultures (if systemic symptoms are present), draw around the edge of the raised area (monitor spread)
What is the treatment for cellulitis?
first line
- flucloxacillin 500mg-1g four times a day for 5-7 days
first line - penicillin allergy
- clarithromycin 500mg twice a day
- erythromycin 500mg four times a day (used in pregnancy)
- doxycycline 200mg on the first day then 100mg daily
severe infection
- cefuroxime 750mg-1.5g three or four times a day IV
- co-amoxiclav 500/125mg three times a day
What antibiotics should be added if MRSA infection is present alongside cellulitis?
vancomycin 15-20mg/kg two or three times a day IV
teicoplanin initially 6mg/kg every 12 hours for three doses then 6mg/kg once a day IV
What antibiotics should be avoided in cellulitis and why?
penicillins
- staphylococcus secretes penicillinase/beta lactamase which breaks down the beta lactam ring in penicillins resulting in loss of function
= cannot use benzylpenicillin, ampicillin. amoxicillin
- flucloxacillin can be used as its too large to be affected by beta lactamase
