Urinary Tract Infections

Sirilak yimcharoen

Definition
n UTI involve only the lower urinary tract or

both the upper and lower tracts

n cystitis : dysuria, frequency, urgency, and

occasionally suprapubic tenderness n acute pyelonephritis : flank pain tenderness, fever n Uncomplicated UTI : infection in structurally and neurologically normal urinary tract

Definition
n Complicated UTI : infection with functional or

structural abnormalities, indwelling catheters ,calculi, men, pregnant, children, hospitalized or in health care

n Chronic UTI : persistence of the same organism for

months or years with relapses after treatment

n chronic pyelonephritis : pathologic changes in the

kidney caused by infection only

Pathologic Characteristics
n Acute pyelonephritis : n enlarged, yellowish, raised abscesses n histologic :suppurative necrosis or abscess formation in renal substance. n Chronic Pyelonephritis : n parenchyma shows interstitial fibrosis with inflammatory infiltrate of lymphocytes, plasma cells n papillary atrophy and blunting n dilatated tubules contain colloid casts

Pathogenesis of Urinary Tract Infection

n

UTIs occur as result of

n n n

bacterial virulence n Adhesins,fimbriae,hemolysin host biologic behavioral factors

Routes of the infection

- the ascending
- hematogenous - lymphatic pathways

Epidemiology of Urinary Tract Infection

Infection organisms n More than 95% of UTIs caused by a single bacterial n E. coli is the most frequent infecting organism in acute infection n In recurrent UTIs caused by
n n n n n n

Proteus Pseudomonas Klebsiella Enterobacter spp. enterococci staphylococci

Epidemiology of Urinary Tract Infection

Infection organisms n Anaerobic organisms rarely pathogens in the urinary tract n Fungi (Candida spp.) occur in patients indwelling catheters and receiving antimicrobial therapy n Adenoviruses (type 11) causative agents in hemorrhagic cystitis in allogenic hematopoietic stem cell transplant recipients

Bacteriuria in adults
n prevalence of asymptomatic bacteriuria

increases in the female n prevalence of bacteriuria in young nonpregnant women is about 1% to 3%. n risk factors for urinary infection in women
n Frequent

sexual intercourse n diaphragm use especially with a spermicide n lack of urination after intercourse n history of recurrent infections

Bacteriuria in older adult

n 10% of men ,20% of women older than 65 years

have asymptomatic bacteriuria n older than 65 years the ratio alters dramatically, with a progressive decrease in the female-to-male ratio n reasons for high frequency of UTIs in older
n n n n

obstructive uropathy from the prostate loss of bactericidal activity of prostatic secretions soiling of the perineum from fecal incontinence bladder catheter usage

Risk Factors for Urinary Tract Infection

Clinical Manifestations
SYMPTOMS n The lower tract symptoms
n frequent n painful

urination of small amounts of turbid

urine n suprapubic heaviness or pain n grossly bloody or bloody tinge at the end of micturition

Clinical Manifestations
SYMPTOMS n The upper tract symptoms
n fever

(sometimes with chills) n flank pain n frequently lower tract symptoms

n In older patient symptoms of UTI are often

atypical (e.g., abdominal pain, change in mental status)

Diagnosis
Presumptive diagnosis of UTI n pyuria :
n at

least 10 leukocytes/mm3 of midstream urine n symptomatic or asymptomatic bacteriuria have pyuria

n White cell casts
n presence

of an acute infectious process are strong evidence for pyelonephritis

Diagnosis
Presumptive diagnosis of UTI
n Proteinuria
n

less than 2 g of protein/24 hr

n Microscopic examination (bacterial count in urine

sample uncentrifuged centrifuged

unstained(x400) 106 105

Stained (x1000) 105 104

Diagnosis
Presumptive diagnosis of UTI Dipstick n leukocyte esterase test positive n detection of pyuria n urine nitrite positive n common gram-negative organisms contain enzymes reduce nitrate in urine to nitrite n some UTIs are caused by organisms that do not convert nitrate to nitrite (e.g., staphylococcus, streptococci) n False-negative test results are common, in detection of low count bacteriuria (102 to 103/mL) n negative leukocyte esterase test plus a negative nitrite test result are strongly predictive of the absence of UTI

Diagnosis
BY CULTURE n methods for urine collection
n n n

midstream clean catch catheterization suprapubic aspiration

n asymptomatic woman n 80% probability represents true bacteriuria when bacteria/mL in a clean-catch urine more than 105 n 95% of the time 104 to 105 bacteria/mL represents contamination

Diagnosis
BY CULTURE
n In men n 103 or more organisms/mL in one culture is suggestive of infection n 105/mL defines bacteriuria n patients with infection from Enterobacteriaceae.

Gram-positive organisms, fungi, and bacteria with fastidious

n n n

may not reach titers of 105/mL may be in the 104 to 105/mL often contain saprophytic skin organisms

Diagnosis
UTI with Low Numbers of Organisms
Exclude vaginitis and herpes genitalis(10%)

Urine culture

105 bacteria/ml(50%)

<105 bacteria/ml acute urethral syndrome (40%)

Bacterial lower urinary tract infection (18%)

Chlamydial (8%)

Unknown (14%)

Diagnosis
UTI with Low Numbers of Organisms n urethritis (chlamydial, gonococcal, or mycoplasmal)
n gradual

onset of milder dysuria n with or without frequency and urgency n vaginal discharge or bleeding may be present n pyuria
n herpes n usually lesions in the periurethral area

Management of Urinary Tract Infection

n All symptomatic UTI should be treated n asymptomatic bacteriuria

treatment no treatment - pregnancy - older patient - children - before transurethral resection of the prostate

Management of Urinary Tract Infection

NONSPECIFIC THERAPY n Hydration
n rapid

dilution of the bacteria and removal of infected urine n increased vesicoureteral reflux n larger urine output results in dilution of antibacterial and in lower urinary concentrations of antimicrobial agents n no evidence that forcing fluids improves the results of appropriate antimicrobial therapy

Management of Urinary Tract Infection

NONSPECIFIC THERAPY Urinary antibacterial activity of urine results mainly from
n high

urea concentration n high osmolality n lower pH

Response to Therapy
n

Bacteriologic Cure
n

negative urine cultures on chemotherapy and during the follow-up period, usually 1 to 2 weeks persistence of significant bacteriuria after48 hours of treatment persistence of the infecting organism in low numbers in urine after 48 hours Sites of persistence in the urinary tract are the renal parenchyma, calculi, and prostate.

Bacteriologic Persistence
1) 2) n

Response to Therapy
n Bacteriologic Relapse n occurs within 1 to 2 weeks after the cessation of chemotherapy n often associated with renal infection, structural abnormalities, chronic bacterial prostatitis n Relapses occurring within 1 week are usually true relapses n Delayed relapses (more than 1 to 2 weeks after stopping therapy) more likely to be result of chronic bacterial prostatitis

Response to Therapy
n Reinfection n occur during the administration of chemotherapy or at any time thereafter n change in bacterial species

Classification and antimicrobial therapy for different groups

Acute Pyelonephritis n gram-negative bacillus infection
n community-acquired
n

UTI

trimethoprim (100 mg twice daily) n trimethoprim-sulfamethoxazole (one doublestrength tablet twice daily) n fluoroquinolones (e.g., ciprofloxacin or levofloxacin)

Classification and antimicrobial therapy for different groups

Acute Pyelonephritis n gram-negative bacillus infection
n suspected
n

bacteremia, complicating pyelonephritis

empirical therapy
piperacillin-tazobactam, as 18 g of piperacillin/day ampicillin-sulbactam, as 12 g of ampicillin/day third-generation cephalosporins

Classification and antimicrobial therapy for different groups

Acute Pyelonephritis n gram-positive cocci infection
n

gram-positive cocci in chains n ampicillin n amoxicillin gram-positive cocci in cluster n vancomycin for inpatients n linezolid for outpatients n because of increasing frequency of infection with community-acquired methicillin-resistant staphylococci

Classification and antimicrobial therapy for different groups

Acute Pyelonephritis n If a bacteriologic response does not occur by 48 hours, there is no point in continuing the same regimen n The finding of continuing positive blood cultures or persistent high fever and toxicity past the first 3 days suggests the need for investigation to exclude urinary obstruction or intrarenal or perinephric abscess formation

Classification and antimicrobial therapy for different groups

Acute Pyelonephritis n uncomplicated pyelonephritis
n complete
n

course of 14 days of antimicrobial

pregnant n severely ill patients

n Follow-up

u/c should be obtained within 1 to 2 weeks of completion of therapy in pregnant women, recurrent symptomatic n use 7 days of therapy
n

mild to moderately ill nonpregnant

Classification and antimicrobial therapy for different groups

Lower Urinary Tract Infection n Conventional Therapy
n

superficial mucosal infection

n Short-Course Therapy n defined as 3 or fewer days of treatment n Single-dose therapy n high urinary concentrations that are prolonged for at least 12 to 24 hours and eliminates infection when presumably confined to the bladder n oral doses of 3 g of amoxicillin n one to two double-strength tablets of trimethoprimsulfamethoxazole

Classification and antimicrobial therapy for different groups

n Short-Course Therapy n Multiple reviews concluded that 3 days of therapy are superior to single-dose therapy n standard doses for treatment of uncomplicated lower tract infection in women : use 3 days of therapy n Short-course therapy is not appropriate for
n n n

women who have a history of previous urinary infection caused by antibiotic-resistant organisms more than 7 days of symptoms in males (7 to 10 days of therapy)

Classification and antimicrobial therapy for different groups

Asymptomatic Bacteriuria

Classification and antimicrobial therapy for different groups

Asymptomatic Bacteriuria n Screening for and treatment of asymptomatic bacteriuria is recommended
n Pregnant
n

women (A-I)

duration of antimicrobial therapy should be37 days (A-II)

n before

(A-I) n before other urologic procedures for which mucosal bleeding is anticipated (A-III)

transurethral resection of the prostate

Classification and antimicrobial therapy for different groups

Asymptomatic Bacteriuria n Screening or treatment of asymptomatic bacteriuria is not recommended
n n n n n n

Premenopausal, nonpregnant women (A-I) Diabetic women (A-I) Older persons living in the community (A-II) Elderly, institutionalized subjects (A-I) Persons with spinal cord injury (A-II) Catheterized patients while the catheter remains

in situ (A-I)

Classification and antimicrobial therapy for different groups

Relapsing Urinary Tract Infection n Cause of relapse
(1) (2) (3)

renal involvement a structural abnormality of the urinary tract (e.g.,calculi) chronic bacterial prostatitis

Patients who relapse after a short course or 7 to 10 days of therapy and absence of structural abnormalities should be considered for a 2-week course

Classification and antimicrobial therapy for different groups

Reinfection of the Urinary Tract n divided into two groups
(1)

(2)

those who have relatively infrequent reinfections, perhaps only once every 2 or 3 years to several times a year those who develop frequent reinfections

Women with reinfections associated with lower tract symptoms can be managed with short-course therapy

Classification and antimicrobial therapy for different groups

Reinfection of the Urinary Tract n In women
n Voiding

immediately after intercourse prevent reinfection n single-dose prophylactic chemotherapy taken after sexual intercourse
ciprofloxacin 125 mg n a single-strength trimethoprim-sulfamethoxazole tablet
n

Classification and antimicrobial therapy for different groups

Reinfection of the Urinary Tract n Long-term chemoprophylaxis
n

n n n

considere for n asymptomatic patients who reinfect frequently and are at risk of developing renal parenchymal damage n all renal transplantation patients to prevent infection of the graft not decreased risk of UTI increased risk of resistant infections Trimethoprim-sulfamethoxazole, nitrofurantoin, or trimethoprim

Classification and antimicrobial therapy for different groups

Fungal Infections n Candida urinary tract infections occur in patients with indwelling catheters n treatment
n Continuous

amphotericin B bladder irrigation n oral fluconazole, 200 to 400 mg/day for 7 days n removing (if possible) or replacing the catheter n no benefit in treatment of asymptomatic infection, except patient undergo elective urinary tract surgery

Urinary tract infection in pregnancy

Management of Bacteriuria of Pregnancy n all women should be screened in the first and third trimesters of pregnancy n ATB for 7 days (e.g., a sulfonamide, amoxicillin, amoxicillin-clavulanate, cephalexin, nitrofurantoin) n Urine cultures should be obtained 1 to 2 weeks after discontinuing therapy

complication of UTI
Perinephric Abscess n uncommon complication n secondary to obstruction of an infected kidney or calyx or occasionally secondary to bacteremia n symptoms
n n n n n

syndrome suggestive of acute pyelonephritis fever abdominal and flank pain palpable mass may or may not be present 50% of patients have an abnormal plain film of the abdomen

complication of UTI
Intrarenal Abscess n consequence of bacteremia n often caused by coagulase-positive staphylococci n clinical setting
n n n n

acute pyelonephritis high fever severe flank pain, and tenderness, no or very slow response to appropriate antimicrobial therapy.

complication of UTI
Intrarenal Abscess
n CT

n intense

parenchymatous inflammation and edema in a lobe of the kidney n termed acute lobar nephronia or acute focal bacterial nephritis

complication of UTI
Diagnosis complication of UTI n urinalysis
n 70%

of patients with a corticomedullary abscess urinalysis abnormal n usually normal in perinephric abscess
n Confirmation of the diagnosis requires renal

ultrasonography or CT scans

complication of UTI
Therapy n perinephric abscess
n n n

percutaneous drainage Surgical antimicrobial therapy

n intrarenal abscesses n diameter 3 cm antibiotic therapy alone n diameter 3 to 5 cm percutaneous or open surgical drainage n diameter>5 cm percutaneous or open surgical drainage

Summary of treatment approaches

The end