UTI's Flashcards
General findings
Una UTI in gravidanza richiede sempre analisi delle urine ed esame colturale!🧨
Urinary tract infections (UTIs) are classified based on location as upper or lower UTIs, and based on presentation as complicated or uncomplicated. In particular, infection of the bladder is known as cystitis. UTIs are most commonly caused by Enterobacteriaceae, especially Escherichia coli. Women are at high risk of contracting UTIs due to a shorter urethra and the proximity of the anal and genital regions. Other risk factors include sexual intercourse, indwelling urinary catheters, pregnancy, and abnormalities of the urinary tract. Patients present with suprapubic pain, dysuria, urinary urgency and frequency. In typical presentations, clinical diagnosis is often possible and can be supported with findings of pyuria on urinalysis or positive leukocyte esterase and nitrites on a urine dipstick test. Further evaluation with urine culture and/or imaging may be required for patients with complicated cystitis. First-line empiric treatment options for uncomplicated cystitis include trimethoprim-sulfamethoxazole, nitrofurantoin, and fosfomycin. Pregnant women with cystitis should be screened and treated for asymptomatic bacteriuria.
Etiology
Bacteria: usually caused by an ascending bacterial infection from the urethra
Enterobacteriaceae (gram-negative rods)
Escherichia coli: in ∼ 80% of UTIs
Proteus mirabilis: urease-producing → causes alkaline urine with an ammonia smell
Klebsiella pneumoniae
Uncomplicated UTI
Immunocompetent, premenopausal women that are neither pregnant nor have any condition that predisposes them to an increased risk of infection or failed therapy
Complicated UTI
SEMPRE urinocoltura!
Il fallimento della terapia antibiotica, anche se in una iniziale cistite non complicata, è indicazione, dopo la seconda linea di farmaci a esecuzione di URINOCOLTURA!
Tutto ciò che non rientra nelle caratteristiche di cui sopra
Male patient
Pregnant women
Children or postmenopausal women
Presence of any significant functional or anatomical abnormalities (e.g., BPH, obstruction, stricture)
History of urological pathologies (e.g., neurogenic bladder, kidney cysts, stones)
History of impaired renal function or renal transplantation
Diabetes mellitus
Immunocompromise (e.g., transplant recipients, HIV/AIDS)
Recent history of any instrumentation (e.g., cystoscopy)
Recent placement of any medical devices (e.g., urinary catheter, nephrostomy tubes, or stents)
🧨Infection with a resistant uropathogen or recent antibiotic use
UTI that spreads beyond the bladder (sepsis, pyelonephritis, prostatitis)
Recurrent UTI (profilassi mediante somministrazione di bactrim)
≥ 3 infections/year (o maggiore/uguale a 2 ogni 6 mesi)
Clinica
NB Fever is usually absent in lower UTIs; therefore, fever and flank pain should be taken as a sign of more serious infection, such as pyelonephritis.💥
- Dysuria, frequency, urgency
- Suprapubic pain
- Gross hematuria may be present! attenzione
Diagnosi
ATTENZIONE: The presence of WBC is the most important indicator of UTI. The presence of bacteria without pyuria may indicate contamination, rather than a true UTI👓
- Clinical diagnosis in healthy women with a typical presentation
- In patients with an atypical presentation, urinalysis is the most important diagnostic test for cystitis (perchè ci permette di visualizzare eventualmente leucociti. Ricorda infatti che l’elemento cruciale per la diagnosi sono i leucociti e non i betteri).👓
Dipstick urine test
se negativo non esclude la diagnosi
!Best initial test
Findings indicative of UTI:
1.Positive leukocyte esterase (Indicates the presence of WBCs in the urine)
2.Positive nitrites (Gram-negative bacteria, such as enterobacteriaceae, convert nitrates to nitrites, and thus have positive results. False-positive results may occur if the patient has ingested chemical dyes or foods that turn the urine red. False-negative results may occur in cases with a low numbers of pathogens and a low-nitrate diet. If the UTI is caused by Gram-positive bacteria, nitrites are negative.)
3.Urine pH may be > 7 (alkaline) in Proteus mirabilis
infections🧨
Urinalysis with microscopy
In contrast to a urine dipstick, normal findings on urine microscopy can rule out a urinary tract infection Questo significa che in forte sospetto di UTI con dipstick negativo non si può escludere l’infezione!!!🧨 (anche se con il forte sospetto di cistite e analisi urine negativa si procede con urinocoltura).
!Confirmatory test
- Required in children and adolescents💥
- Clean-catch midstream specimen is necessary to avoid contamination with vaginal or skin flora. Straight catheterization of the bladder or suprapubic aspiration can also be performed if a clean catch cannot be obtained without contamination (e.g., in children who are not toilet trained.)
Diagnostic criteria for UTI (al microscopio)
1.Pyuria: ≥5-10 WBC/high power field
2.Bacteriuria: presence of bacteria on Gram stain (most commonly, gram-negative rods)
3.Leukocyte casts should be absent in lower UTIs.
Leukocyte casts are indicative of pyelonephritis!!
Urine culture
Diagnostic criteria for UTI
- Significant bacteriuria defined as ≥ 10/5 colony forming units (CFU)/mL serves to confirm a UTI. (If patients present with the following symptoms (e.g., dysuria, frequency, and urgency), urine cultures with ≥ 10/3 CFU/mL suffice to diagnose a UTI.)
- Any bacteriuria (qualsiasi CFU) in urine from a suprapubic aspiration of the bladder is abnormal.
Urine culture is not always required, but only in the special cases listed below.💥
- Patients with complicated UTI
- Age older than 65 years
- Use of a diaphragm
- Recent use of antibiotics
Suspected cystitis with the following characteristics:
- Duration of symptoms greater than 7 days
- High suspicion of cystitis with a non-diagnostic urinalysis
- Recurrent UTIs
- Suspicion of pyelonephritis or urosepsis
Diagnostic imaging
utile per indagare anomalie strutturali o eventuali ritenzioni urinarie
👓Indication: complicated cystitis, suspicion of structural abnormalities
1.Ultrasound: allows urinary retention to be ruled out (idronefrosi) ; may also show signs of pyelonephritis
!Children <24 months with a urinary tract infection should undergo renal ultrasound in case there is a kidney or urinary tract abnormality
- Cystoscopy: evaluates for unusual findings on urinalysis, stones, reflux, urinary obstruction, polyps or malignancies, and interstitial cystitis
- CT: investigates possible urinary tract pathologies, such as stones, obstruction, tumors, cysts, and trauma
- Intravenous pyelogram (IVP): to look for structural abnormalities, mainly obstructions
Differential diagnoses
Interstitial cystitis
Rare, chronic, noninfectious cystitis with an unknown etiology that causes suprapubic pain and scarring of the bladder wall
- Urgency and frequency
- Symptoms for at least 6 weeks
- Relieved by voiding and worsened by bladder filling (most common feature)
Diagnosi
- Clinical diagnosis after exclusion of other diagnoses
- Urinalysis with microscopy: required to exclude other diagnoses
Trattamento
- Behavior modification (first-line): avoid triggers, fluid management based on symptoms, bladder training
- Oral medications (second-line): Amitriptyline is most commonly used and works as an analgesic and antidepressant.
- Invasive procedures in the bladder (third-line)
Other differential diagnoses
- Vaginitis : presents with dysuria without urinary frequency or urgency but is often accompanied by other symptoms, such as odor, discharge, or pruritus.
- PID : pelvic pain may be mistaken for suprapubic pain, but urinary symptoms are usually absent.
- Urethritis with sexually transmitted infections (Neisseria gonorrhoeae, Chlamydia trachomatis, etc.), Candida, or irritants. Suspect urethritis in a sexually active patients with sterile pyuria.
Principles of therapy
- Empiric treatment can be given for uncomplicated cystitis; local resistance patterns should guide the choice of empiric therapy.
- Persistent symptoms after 48–72 hours of antibiotic therapy suggest possible complicated cystitis or necessitate that empiric therapy be changed.
- Phenazopyridine, a urinary analgesic, can be used for dysuria for 1–3 days.
First-line treatment for acute uncomplicated cystitis in nonpregnant women
- Trimethoprim-sulfamethoxazole (TMP-SMX)
- Nitrofurantoin: avoid if patient has renal insufficiency or if pyelonephritis is suspected
- Fosfomycin: avoid in suspected pyelonephritis
