Week 6- Urinary tract infections Flashcards
where do infections most commonly ascend from in UTIs
urethra
what mechanisms are in place to avoid UTIs
- diluting and flushing action of urine
- valve between bladder and ureter prevents reflux
- extreme low pH, high osmolarity, IgA secretion, high urea concentration
- proteins that prevent attachment
which proteins prevent attachement to avoid UTIs
- Tamm Horsfall protein (uromodulin) produced by kidney, coats epithelium binds E.coli
- GP51 protein secreted by bladder epithelial cells binds many bacteria preventing adhesion
- Manno-oligosaccharide in urine- binds E.coli
what are risk factors of UTIs
- catheterisation -CAUTI
- obstruction
- vesicoureteric reflux
- pregnancy
- diabetes
- autonomic neuropathy leads to incomplete emptying of the bladder
what obstructions can cause UTIs
enlarged prostate, urinary stones, congenital malformations
what is Vesicoureteric reflux caused by
abnormal valve development
how can pregnancy cause UTIs
impaired urine flow due to hormonal changes (may cause dilution of ureters) and pressure on the UT
what are the community associated UTIs
- staphylococcus saprophytic- common in sexually active women
- ESBL- producing E.coli are seen in community patients who have had no contact with the health care system
what is hospital associated UTI
pathogens are often resistant to antimicrobial
what is Candida albicans
unicellular yeast which divides by budding
what is Candida albicans commensal on
skin, GIT, female genitalia
what is Candida albicans associated with
urinary catheters
slide 10
what is cystitis
inflammation of the bladder caused by E.coli. accounts for 95% of lower UTIs
what are symptoms of cystitis
dysuria frequency, suprapubic pain (pain in the lower abdomen)
what is acute pyelonephritis
infection of the kidney which is most commonly caused by E.coli
what are symptoms of acute pyelonephritis
flank pain, fever, nausea, vomiting, rigors
what is chronic pyelonephritis
chronic inflammation of the kidneys
what is chronic pyelonephritis associated with
- obstruction of the urinary tract
- vesicoureteric reflux in children
when is a short term Foley catheter used
during operations
what is short term foley catheter made up from
latex
when is a long term Foley catheter used
prostate problems, physical disability
what is long term foley catheter made up from
silicone, PVC, teflon, silver coated
what kind of pathogens can be sources from CAUTI
- endogenous (metal, rectal, or vaginal colonisation)
- exogenous: usually via contaminated hands or manipulation of the collecting system
what are the leading pathogens of CAUTI
e.coli, pseudomonas, klebsiella, serratia, staphylococci, enterococci and candida
how do biofilms form
bacterial growth on the surface, urinary proteins, urinary salts
how are symptoms from CAUTI resolved
removal of catheter
what is mid-stream urine (MSU)
accounts for majority of samples. first urine passed is discarded - contaminated with organism colonising the distal region of the urethra. Mid-stream urine collected in a sterile pot
what is catheter stream urine (CSU)
samples taken through a port aseptically
how are urine samples collected from very young children
- pad urine
- bag urine
- clean-catch urine
- suprapubic aspirate
what is pad urine
absorbents pad placed in nappy and checked regularly
what is bag urine
bag collects the sample
what is clean-catch urine
sample caught into a sterile container (equivalent to MSU)
what is suprapubic aspirate
a needle through the skin aspirates urone directly from the bladder (collected if alternatives have failed)
why should samples be transported quickly at lower temperatures
to avoid false positive results
what should be done if there are delays with transporting a sample
- Refrigerate at 4°C for max. of 24 h
- add boric acid to preserve
- use a dip-slide. commercially available agar coated slide dipped int freshly voided urine
what information can help confirm an infection from a sample
- detection of a single bacterial pathogen associated with UTI-bacteriuria
- elevated number of white blood cells (WBC) in the sample- pyuria
- observation of fungi or parasites in the sample
how is microscopy used in sample processing
slide 27
what does direct microscopy show
- epithelial cells- indicates skin contamination
- bacterial cells, fungi and parasites- visible bacteria is not diagnostic; fungi or parasites is diagnostic
- casts- proteinaceous structures produced by the kidneys. may occur due to different pathologies
