Microbiology 10 - Urinary Tract Infections Flashcards
(30 cards)
What are squamous epithlial cells in a MSU indicative of?
Contamination as they are found at the end of urethra
(urethra is NOT sterile) but bladder is sterile
When is asymptomatic bacteriuria significant?
PREGNANCY
When is cystitis considered to be complicated?
functional or structural abnormalities (including indwelling catheters and calculi)
Men
Pregnant women
Children (not young girls)
Patients in a healthcare- or HC-associated settings
Which organism is the most common cause of UTI?
E coli
have adherance factors that prevent them from being flushed out by passage of urine
ex recurrent (increases NON ecoli)
What is the 2nd most common cause of UTI in younger women?
Staphylococcus saprophyticus (coagulase -ve staphylococcus)
Virulence factors (P-fimbriae) allow adherence to epithelium
Which organism is associated with kidney stones?
Proteus mirabilis
Which organism is associated with the presence of prosthesis e.g. procedures or long time indwelling catheters
Staphylococcus epidermidis
why are females more likely to get UTIs?
female urethra short and in proximity to vulvar and perianal areas → contamination likely
Massage of urethra and sexual intercourse can force bacterial → bladder
Why do renal tract abnormalities increase risk of UTIs?
Obstruction inhibits flow of urine → stasis → ↑ susceptibility to infection
What are some extrarenal causes of obstruction
Valves, stenosis or bands
Calculi
BPH
What are some intrarenal causes of obstruction
Nephrocalcinosis
Uric acid nephropathy
Analgesic nephropathy
PKD
Hypokalaemic nephropathy
Renal lesions of SCD
How may neurogenic malfunction result in kidney obstruction?
Poliomyelitis
Tabes dorsalis
Diabetic neuropathy
Spinal cord injuries
how does VUR perpetuate infection?
residual pool of infected urine in bladder after voiding
can result in scarring of kidneys
what does S aureus in the urine indicate?
Kidney frequent site of abscesses in patients with S. aureus bacteraemia or endocarditis
S. aureus does NOT have appropriate virulence factors to cause ascending infection
I.E. if you see S. aureus in the urine → not UTI, more likely to be abscess
what does gram negative organisms in the urine indicate?
rarely through haemotegenous - so likely UTI
What are the symptoms of UTI in babies?
Vomiting, failure to thrive, fever
What are the symptoms of pyelonephritis?
Fever, rigors, flank pain and urinary symptoms
What are the symptoms of UTI in older patients?
ast majority ASYMPTOMATIC
Diagnosis difficult as non-infected older patients often experience frequency, dysuria, hesitancy & incontinence
often atypical (e.g. abdominal pain, confusion)
Interpret the results of a urine dipstick in terms of leucocytes and nitrites
How would you manage UTI in older adults?
No diptick - more unrealiable with ↑ age
Abx not beneficial and may cause harm (e.g. C diff)
What do nitrites suggest in a urine dipstick?
E. coli (coliforms) produces lots of nitrites so suggestive of an E. coli UTI if found
If nitrite -ve and LE +ve, the cause may be a non-coliform bacterium (i.e. not E. coli)
Which microorganisms should you consider in a sexually active young man with a UTI ?
chlamydia trachomatis
Renal USS
IV urography
What does this urine microscopy suggest?
squamous epithelial cells look like fried eggs - failed MSU technique
What should you consider if there is a sterile pyuria (raised WCC but no growth on culture)
Prior treatment with antibiotics (MOST COMMON)
Calculi
Catheterisation
Bladder neoplasm
TB
STI (Chlamydia trachomatis)
