UTI Flashcards
Which group of patients are at risk of urinary tract infection?
- child <3 yr old (underlying abnormalities eg spina bifida, vesicourethral reflux)
- yg female
- elderly
- catheterised pt (hosp/stroke)
- underlying abnormalities
What are the predisposing factors for urinary tract infections?
- reflux - vesicourethral angle not acute
- calculi
- prostatism
- congenital
- catheter
- neurological
- pathogen factors (attachment, type 1, P fimbriae)
What are the 2 sites of UTI?
- Upper UTI (pyelonephritis)
- Lower UTI (cystitis)
- bacteraemia = upper tract infection
What are the likely pathogens?
- E coli
2. Staphylococcus saprophyticus
In pt w structural anomalies/ catheter, what kinds of UTI pathogens are common?
- Proteus
- Pseudomona aeruginosa
- Enterococcus
- candida
Where should you collect urine specimen?
- catheterised pt: collect from port and not from bag
2. clean catch urine
What should you do when collecting urine specimen?
- Clean adequately
- Collect before antibiotics
- Transport immediately to lab
What is a screening tool for UTI?
Urine dipstick
- rbc (haem),
- wbc (leukocyte esterase),
- nitrates (E coli metabolites)
- note but err on oversensitivity so need microscopy
What are the possible findings of urine microscopy?
- Hematuria: RBC > 100/uL + WBC > 100/uL
2. Pyuria: WBC > 100/uL + RBC <10/uL
If WBC count is low, does it mean patient does not have UTI?
No, as
- dilution effect
- WBC degraded on storage
Diagnosis of UTI using urine culture
- Single colony + >100,000 cfu/mL : significant
- 1000-100,000 cfu/mL + single colony: may also be significant
- mainly gram -ve
How do you know if urine culture is inaccurate?
- Mixed growth
- Overgrowth if > 90min storage & transport –> false positives
- Non pathogenic species eg coagulase-negative staph
so need to take into account Bacterial count Mixed / single organism Presence or absence of catheter Patient’s age and background
What’s needed to diagnose UTI?
Any 2 of 3
- Symptoms
- Urine WBC ++ pyuria
- Culture ++ growth
How long do you treat uncomplicated UTI?
3 days
How long do you treat upper tract infection?
at least 2 weeks
- look for underlying abnormalities
What are the empiric antibiotics for UTI?
- Cotrimoxazole
- Amoxy-clavulanic acid
- Cephalosporins
- Aminoglycosides
- Fluoroquinolones
What are the antibiotics ONLY used for lower tract UTI?
- Nitrofurantoin
2. nalidixic acid
What are the antibiotics used for uncomplicated UTI?
Oral cephalosporins
Antibiotics not for X urinary infection
Erythromycin &
Clindamycin
Special cases
Pyelonephritis Recurrent UTI Paediatric UTI Catheter-associated UTI Asymptomatic bacteriuria
Sexually-transmitted diseases
Ulcer
Syphilis *
Haemophilus ducreyi
Herpes simplex virus
Discharge
Neisseria gonorrhoeae *
Chlamydia trachomatis *
Warts
Human papillomavirus
Systemic
HIV, hepatitis B
Others
lymphogranuloma venerum
What are the tests for syphilis?
Treponema:
- TPHA
- EIA
Non-treponema:
1. VDLR
Rapid plasmid reagin:
RPR
Which would be the syphilis screening test recommended?
TPHA/EIA as life long positives
What must you take note of if TPHA/EIA used to screen for syphilis?
Cross-reactivity with non-syphilis treponema infection
eg yaws
Why not use VDLR or RPR to screen for syphilis?
- biological false positives
- false negatives due to pro-zone
- more used to monitor disease activity
How do you screen for Neisseria gonorrhea?
Lab tests:
1. Culture on Thayer-Martin agar
(use Amies transport media +/- charcoal)
2. PCR, usually w chlamydia PCR - replace culture but no info on susceptibility
Treatment of N gonorrhea
high prevalence of penicillin resistance (penicillinase + PBP)
- ceftriaxone (emerging resistance)
- alt: azithromycin
- X ciprofloxacin
- concurrent chlamydia: doxycycline
How do you screen for chlamydia?
screen sex active women – 25 yr old
- CT PCR (cyclic threshold-CT)
- endocervical, vagina, urine specimens
Treatment of chlamydia
doxycycline
azithromycin
What are the causes of vaginal discharge?
- candida
- bacterial vaginosis (gram stain, VP3 DNA probe test)
- trichomonas vaginalis (wet mount, PCR)
Reasons for a negative culture but with UTI symptoms and pyuria
- Started on antibiotics
- “acute urethral syndrome”
- Due to chlamydia, other organisms
- With symptoms, may respond to treatment - Others e.g. TB
What measures can be taken to overcome the problem of prolonged transport time for urine?
Keep in fridge 4 deg C – send within 24 h
Boric acid in container (supplied by lab)
Urine dipslide
