Urinary Tract Infection Flashcards
Name infection of kidney
Acute or chronic pyelonephritis
Name infection of the bladder
Cystitis
Name infection of the urethra
Urethritis
Name infection of prostate
Prostatitis
Name infection of the epididymis/Testis
Epididymo-orchitis
What are the two classifications of UTIs?
- Uncomplicated: normal renal structure + function
* Complicated: structural/functional abnormality of urinary tract
What are general predisposing factors which makes an individual more susceptible to UTI (or other infection)?
- Immunosuppression
- Steroids
- Malnutrition
- Diabetes
What are predisposing factors specific to the urinary tract?
- Female sex (short urethra)
- Sexual intercourse and poor voiding habits
- Congenital abnormalities e.g. duplex kidney, PUJ obstruction
- Stasis of urine e.g. due to poor bladder emptying
- Foreign bodies eg catheters, stones
- Oestrogen deficiency in postmenopausal women
- Fistula between bladder & bowel
- Renal cysts
- Pre-existing renal parenchymal damage (i.e. recurrent pyelonephritis)
What is acute pyelonephritis?
Infection of upper urinary tract involving the kidneys/renal pelvis
• Commonly women of child bearing age
What is chronic phyelonephritis?
Pathological condition with renal scarring and potentially loss of renal function. Infection may be a contributory cause but the term does not necessarily imply ongoing infection. Other factors which may contribute include diabetes, vesico-ureteric reflux and urinary obstruction
What are the common causative organisms?
Usually anaerobes and gram-negative bacteria from bowel and vaginal flora.
- E coli (commonest)
- Proteus
- Klebsiella
- Enterococcus
What is sterile pyuria?
Urine is negative on culture but significant numbers of pus cells are present.
Describe different routes for bacteria to enter the urinary tract (usually sterile)
Transurethral:
• Periurethral area contaminated (recurrent UTI, diaphragms)
• Urethra to bladder (intercourse, catheterisation)
• Bladder (and u ureters)
- Blood stream
- Lymphatics
What are general clinical features for UTIs in children?
Diarrhoea Excessive crying Fever Nausea and vomiting Not eating
What are general clinical features for UTIs in adults ?
Flank pain Dysuria Cloudy offensive urine Urgency Chills Strangury Confusion (very old people)
What is strangury?
Condition caused by blockage or irritation at the base of the bladder, resulting in severe pain and a strong desire to urinate.
What are the clinical features of acute pyelonephritis?
Pyrexia Poor localisation Loin tenderness (renal angle) Signs of dehydration Turbid urine (cloudy) Vomiting
In severe cases, bacteria spreads to blood stream -> bacteraemia causing sepsis:
• Rigors
• N+V
What are the clinical features of cystitis?
Frequency Dysuria Urgency Suprapubic pain Polyuria (large volume) Haematuria
What investigations are carried out for women?
• Mid-stream sample of urine.
• Dipstick: Blood, leucocytes, protein and
nitrites
Microbiology In lab:
• Microscopy and Gram staining
• Bacteruria >105 CFU /ml
• Culture and sensitivity
What is the typical presentation of acute cystitis or lower tract infection in adult women?
Variable combinations of: • Dysuria • Frequency • Urgency • Suprapubic • Polyuria • Haematuria
What is the management for a women with mild or only 2 symptoms?
MSU
What is the management for a women with >= 3 symptoms of cystitis and no vaginal discharge?
Treat empirically* with no further test, usually 3 days.
*Therapy begun on the basis of a clinical “educated guess”
What can contaminate MSU and how are samples made sterile?
Urine contaminated by urethral contents (from vaginal/labial organisms moving up)
- Take midstream sample
- Wash/swab with sterile saline in advance
What is tested for in dipstick urinalysis?
- Nitrate (metabolic product of bacteria)
- Protein (shouldn’t be in urine - inflammation and renal pathology indicated)
- Leucocytes (marker of inflammatory response)
Is cloudy urine indicative of UTI is women?
Makes it unlikely to be UTI
Describe dipstick results of a UTI
If all 3 are negative, it’s unlikely that Pt has UTI.
If all three positive -> empirical therapy
• Positive leucocytes esterase doesn’t diagnose of exclude, need to carry out urine culture. Same if protein just positive.
In men, why do UTIs increase with age?
Secondary to obstruction cause by prostatic hypertrophy
What condition is recurrent UTIs in men a presenting feature of?
Prostatitis
What is the causative bacteria of prostatitis in men?
- Coliform organisms in older patients
* In younger males, sexually transmitted organisms; chlamydia trachomatis and Neisseria gonorrhoea
What investigations should be carried out for children, men or frequent UTIs?
- USS or IVU
* Isotope studies to rule out reflux and scarring
What are the principles of management?
- Identify organisms and start treatment
2. Identify predisposing factors and treat if possible
What is the management of acute pyelonephritis?
- Urine culture
- Blood culture is systemically unwell
- Immediate antibiotic treatment, more aggressive over 7 days
- Recurrent episode investigated for calculi etc.
What is the management of catheter-related infection?
Long-term catheters mean bacteria will be present, does not mean they have a UTI, so no indication for urine culture or treatment if no symptoms or signs of UTI
Culture and antibiotics if Pt symptomatic and has signs of infection, and catheter should be changed prior to any treatment.
Do you treat asymptomatic bacteria?
No
Unless they’re pregnant or undergoing urological surgery or surgery involving implantation of artificial prosthesis
What is the effect of asymptomatic bacteria in pregnancy?
Increases risk of pyelonephritis and premature delivery
So common to screen with MSU culture and treating those wit significant bacteria
What are causes of sterile pyuria?
- Renal tuberculosis
- Chlamydia trachomatis in the sexually active
- Non-infective; stone, interstitial cystitis, malignancy, chronic prostatitis etc (causes recurrent sterile pyuria)
What is the investigation of suspicion of renal tuberculosis (cause of sterile pyuria)?
Three early morning urine samples for a ZN stain and TB culture
Why is it important to identify children with vesicle-ureteric reflux?
Can lead to renal scarring in later life
• So need to follow up and treat UTI in children
What is the clinical presentation of chronic pyelonephritis?
- Vague abdominal discomfort
- Hypertension
- Sterile urine, but contains pus cells
- IVP changes; clubbing of calyces with scarring or cordial parenchyma
- If ureters dilated -> carry out micturating cystogram to detect VU reflux
What are the features of uncomplicated UTIs?
- Health, sexually active young women
- E coli or skin commensals (staph. aprophyticus)
- No extra investigations
What are the features of complicated UTIs?
• Any UTI in children, men, patients with abnormal renal tract (PUJ obstruction), immunosuppression, foreign body in renal tract (catheter), bladder tumour, chronic urinary retention and abnormal bladder outflow tract (urethral stricture)
Investigations including:
• USS or CT of upper renal tract
• Cystoscopy and post-vois bladder scan
• Urinary flow studies
In what circumstances should cultures be undertaken?
- Women < 2 symptoms
- Men
- Suspected acute pyelonephritis
- Pregnancy or screening
- Failed antibiotic treatment or persistency
- Recurrent UTI (> 2 with 6 months or 3 in a year)
- Children
Where should catheter specimens be taken from?
Sampling port, not collection bag
What is an alternative method to MSU if there is a delay in specimens reach lab?
Dipslide:
Plastic holder coated in agar which is dipped into urine immediately after collection. Organisms in urine are inoculated on agar and will grow in quantities proportional to their collections.
How are MSU samples stored before delivery to labs?
?Refrigerated or collected in containers with boric acid to prevent bacterial overgrowth
How are urine samples collected in children?
Clean catch sample
• If not possible, use urine collection pads
• If non-invasive methods not possible, use a catheter smoke or suprapubic aspiration
What is the process of urine cultures?
Measured amount of urine plated out and number of colonies which grow is proportional to number of organisms in the original sample (organisms/ml)
What are the causative organisms of UTIs?
Ecoli Proteus Enterococcus faecalis Klebsiella Pseudomonas Staph. Saprophyticus
Describe E coli
Most common cause of UTI and strain have specialised projections call P fimbriae which are adherent to eruepithelium (more likely to cause upper urinary infection (pyelonephritis))
Describe Staph. Saprophyticus
Coagulase negative staph which causes UTI particularly in sexually active women
Describe proteus
Produces enzyme urease which splits urea to release ammonia, making urine alkaline and encouraging stone formation
Describe Enterococcus faecalis, Klebsiella and Pseudomonas spp.
Often found in hospital patients, associated with catheters or instrumentation of urinary tract.
More antibiotic resistant (pseud.) and associated with stone formation (proteus or kleb.) so should always investigation upper renal tract imaging
What is the use of microscopy for investigations?
Determine whether or not there are cells, casts or organisms present
• >10 WBC/mm3 in uncentrifuged urine -> significant pyuria
What is the treatment for lower UTI in non-pregnant women (simple cystitis)?
Use antibiotics not used for treatment of other serious infections (prevent resistant bacteria)
• Trimethoprim 3 days
• Nitrofurantoin
What is the treatment for lower UTI in men?
Longer antibiotic cours; 14 days quinolone (i.e. ciprofloxacin) to cover possibility to prostatitis
7 days of nitro. or trimethoprim is infection appears uncomplicated.
What is the treatment for acute pyelonephritis?
7 days ciprofloxacin
Reviewed after results of urine cultures and sensitivity tests known
Resolution checked by urine sample 1-2 weeks after cessation of antibiotic therapy
What treatment should be used in pregnant women?
Nitrofurantoin safe but can cause neonatal haemolysis if used at term
Cephalexin safe but should be guided by sensitivities
What is the management of recurrent infections?
- Drink plenty fluids
- Empty bladder after sexual intercourse
- Personal hygiene
- Gynaecological exam and IVP
- Long term prophylaxis: one tablet of trimethoprim or nitro. per night up to 1 year
- For recurrent uncomplicated UTI, prophylactic antibiotic immediately after intercourse