UTI and Pyelonephritis Flashcards
What is UTI?
Urine is sterile
• Presence of inflammatory cells or
pathogens in urine indicate a UTI
• UTI is the most common bacterial
infection managed in general medical
practice (accounts for 1‐3% of consultations)
* Pathogens can travel up the ureters and reach the kidneys in a minority of cases, causing renal damage and kidney failure
Epidemiology
Urethra length in males and females?
Young, sexually active women 18–24 years of age have the highest incidence of UTIs.
• About 25% of these women have spontaneous resolution of symptoms.
• The prevalence of UTIs in men is significantly lower than in women, occurring primarily in men with urologic structural abnormalities and in older adult men due to prostatic hypertrophy may occur
Females: 18-20cm
Males: 4cm
How are UTIs are named according the area of infection?
Including the name of upper and lower UTI’s?
‐In the urethra = Urethritis
‐In the bladder = Cystitis
‐In the kidneys = Nephritis
‐In the prostate (men) = prostatitis
- Lower UTIs, also known as cystitis
• Upper UTIs, also known as pyelonephritis, develop when uropathogens ascend to the kidneys via the ureters
What is an Uncomplicated UTI?
• Lower urinary symptoms (dysuria, frequency, and urgency) in otherwise healthy non-pregnant women
What is a Complicated UTI?
• Pregnant women, men, obstruction, immunosuppression, renal failure, renal transplantation, urinary retention from neurologic disease, and individuals with risk factors that predispose to persistent or relapsing infection (e.g., calculi, indwelling catheters or other drainage devices)
• Health care associated
CA-UTI (catheter-associated UTI)
• Presence of indwelling urinary catheters with signs and symptoms of UTI and no other source of infection
• Presence of ≥ 10ª CFU/mL in a single catheter urine specimen or in a midstream urine, despite removal of urinary catheter in the previous 48 hr
How do we investigate for Asymptomatic bacteriuria?
• Women: Two consecutive voided urine specimens with isolation of the same bacteria at ≥ 10^5 CFU/mL
• Men: A single, clean-catch, voided urine specimen with 1 bacteria isolated 10^5 CFU/mL
• A single catheterized urine specimen with 1 bacteria isolated ≥ 10ª CFU/mL
What are the Risk Factors for UTI?
- For premenopausal women of any age:
Diabetes
Diaphragm use especially those with spermicide
History of UTI or UTI in childhood
Mother or female relatives with history of UTI
sexual intercourse - Postmenopausal and older adult women: estrogen deficiency
functional or mental impairment
history of UTI before menopause
Urinary catheterization
urinary incontinence - Men and women with structural abnormalities:
* extrarenal obstruction associated with congenital anomalies of the ureter, urethra calculi, extrinsic urethral compression, or benign prostate hypertrophy
- intrarenal, obstruction associates account synthesis, uric acid, nephropathy, polycystic, kidney disease, hypokalemic, or analgesic renal lesions from sickle cell disease
➢Female gender, especially postmenopausal women.
➢New sexual activity, particularly in young
women.
➢Indwelling urinary catheter or
instrumentation of the urinary tract.
➢Urinary tract stones.
➢ Urinary tract stasis (incomplete bladder
emptying).
➢Diabetes mellitus or immunosuppression.
➢Dementia.
Aetiology
• UTI is usually caused by bacteria from a patient’s own bowel flora
• As all portions of the urinary tract connect to each other, infection spreads easily
• More easily in women because of a shorter urethra, moist periurethral environment in women and absence of bacteriostatic prostatic secretions (as in men)
• Catheterisation may also introduce organisms into the bladder
• Rarely, infection may arise from the bloodstream or lymphatics, or by direct extension (e.g. from a vesicocolic fistula).
What are the Organisms causing UTI in practice?
Escherichia coli and other ‘coliforms’: 70
Proteus spp.: 12
Staphylococcus saprophyticus or epidermidisa: 10
Enterococcus faecalis: 6
Pseudomonas spp.: 5
Klebsiella spp.: 4
Uropathogens by Type of UTis
Pathogenesis
Urinary tract infections typically start with
periurethral contamination by a uropathogen residing in the gut,
• followed by colonization of the urethra and, finally, migration by the flagella and pili of the pathogen to the bladder or kidney.
• Bacterial adherence to the uroepithelium is key in the pathogenesis of UTI.
• Infections occur when bacterial virulence
mechanisms overcome efficient host defense mechanisms.
Innate host defence prevents UTI in
the following ways:
❖Neutrophils - Activation of neutrophils is essential for bacterial killing.
❖Urine osmolality and pH - Urinary osmolality >800 mOsm/kg and low or high pH reduce bacterial survival.
❖Complement - Complement activation with mucosal IgA production by Uroepithelium (acquired immunity)
plays a major role in defence against UTI.
❖Commensal organisms - Eradication of commensal organisms such as Lactobacilli, corynebacteria, streptococci and bacteroides by spermicidal jelly or antibiotics results in overgrowth of virulent organisms e.g E. coli
❖Urine flow - Good urine flow and normal
micturition wash out bacteria. Urine stasis promotes UTI
How do we characterize the clinical syndrome as?
• asymptomatic bacteriuria (asymptomatic bacteriuria refers to the presence of bacteria in the urine (urine culture) but patient does not have local or systemic symptoms referable to the urinary tract)
• uncomplicated cystitis,
• pyelonephritis,
• prostatitis, or c
• complicated UTI.
What are the Clinical features of asymptomatic bacteriuria?
What are the typical features of lower UTI (uncomplicated cystitis)?
Asymptomatic bacteriuria refers to the
presence of bacteria in the urine (urine
culture) but patient does not have local or
systemic symptoms referable to the urinary tract
o Frequency of micturition by day and night
o Dysuria (Scalding pain in the urethra during micturition)
o Suprapubic pain during and after voiding
o Urgency (Intense desire to pass more urine after micturition due to spasm of inflamed bladder)
o Cloudy and smelly urine
o Haematuria
Complicated UTI Presents as a symptomatic episode of cystitis or pyelonephritis in a man or woman with;
- Anatomic predisposition to
infection, - Foreign body in the urinary tract, or
- Factors predisposing to a delayed
response to therapy
Systemic symptoms suggestive of pyelonephritis:
• ‐Fever above 38.3°C with chills and rigor, nausea and vomiting
• ‐Loin pain and tenderness
• ‐may be indication for hospitalisation
• UTI can also present with few or no symptoms (particularly in the immunocompromised), or even with abdominal pain, fever or haematuria in the absence of frequency or dysuria.
• In the elderly, new confusion may be the only symptom of UTI.
Prostatitis presents as…
Prostatitis presents as dysuria,frequency,
and pain in the prostatic, pelvic, or
perineal area.
• Fever and chills are usually present, and
symptoms of bladder outlet obstruction
are common.
• Men who present with recurrent cystitis
should be evaluated for a prostatic focus.
What indicates a 95% probability of infection in symptomatic UTIs?
Most symptomatic UTIs have 10^5 CFU/mL or greater, indicating a 95% probability of infection
How to diagnosis investigations
Urinalysis is often used to detect UTIs, and a clean- catch dipstick leukocyte esterase test is a rapid screening test for detecting pyuria, with a high sensitivity and specificity for detecting more than 10 WBC/mm3 in urine
• Collect a clean voided midstream sample
• Urine dipstick tests
• Presence of nitrite and/or leucocyte esterase.
• Gram stain of urine sample (microscopy) - one
bacterium per oil‐immersion field indicates
infection
• Culture of midsteam urine sample (MSU) or urine
from suprapubic aspiration
• Blood culture if fever, rigors or evidence of septic
shock
• Complete blood count
• Definitive diagnosis rests on combination of typical
clinical features with findings in the urine
What does pyuria and Bacteriuria indicate? Why are nitrites a marker of UTI’s?
• Note that presence of pyuria is nonspecific and does not always indicate clinical UTI
• Bacteriuria alone is not a disease and usually does not necessitate treatment
• For symptomatic UTIs, most patients have more than 10 leukocytes/mm3;
• Organisms like E. coli, Klebsiella spp., Enterobacter spp., Proteus spp., Staphylococcus spp., and Pseudomonas spp. reduce nitrate to nitrite in the
urine, and the presence of nitrite on a urinalysis is of another marker of UTIs
General Treatment Considerations
The first step in treating UTIs is to classify the type of infection, such as
• Acute uncomplicated cystitis or
pyelonephritis,
• Acute complicated cystitis or pyelonephritis,
• CA-UTI, asymptomatic bacteriuria (ASB), or
• Prostatitis
Treatment
• Antibiotics are recommended in all proven cases of UTI
• Treatment is best guided by antimicrobial susceptibility tests
• However, empirical treatment must commence while waiting for results
• The most appropriate antibiotic choices are trimethoprim– sulfamethoxazole (160/800 mg twice daily for 5–7 days) or
nitrofurantoin (100 mg twice daily for 5–7 days).
• Fluoroquinolones and oral cephalosporin are also useful
• A high (2 L daily) fluid intake should be
encouraged during treatment and for some
subsequent weeks.
• If the patient is acutely ill with high fever, loin pain and tenderness (acute pyelonephritis), antibiotics are given intravenously, e.g. aztreonam, cefuroxime, ciprofloxacin or gentamicin, switching to a further 7 days’ treatment with oral therapy as symptoms improve.
• Intravenous fluids may be required to achieve a good urine output
UTI in Elderly
• Prevalence of UTI rises with age (40% in women)
• Contributing factors include increased prevalence of underlying structural abnormalities, post‐menopausal oestrogen deficiency in women, prostatic hypertrophy in men, amongst others.
• The urinary tract is the most frequent source of bacteraemia in older patients admitted to hospital
• Symptoms may not follow classic patterns seen in younger adults
• Agitation, change in mental state or other
behavioural changes maybe the only sign
of UTI in elderly
• Left untreated, UTI can lead to delirium or
even death in an elderly
