Urinarytract Infection

Urinary Tract Infections Qiu bo

Anatomy 

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Lower urinary tract ( superficial ) Urethritis cystitis Upper urinary tract ( tissue invasion) Prostatitis Kidney : Acute Pyelonephritis, abscess

Urinary Tract Infection Defined Definition Women: Presence of at least 100,000 colonyforming units (cfu)/mL in a pure culture of voided clean-catch urine Men: Presence of just 1,000 cfu/mL indicates urinary tract infection *Some labs do not routinely identify & determine the sensitivity of organisms for specimens with <10,000 cfu/mL. May have to special request.

Prevalence of urinary tract infections (UTI) 

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almost half of all women will have at least one UTI in their lives. the risk of UTI in women increases after menopause after a UTI, 20 - 40 % will have a recurrence the recurring infections are usually reinfections. asymptomatic bacteriuria in women occurs in  2.7% of 15 - 24 year olds  9.3% of over 65 year olds and 

20 - 50% of over 80 year olds

Prevalence of UTIs 2  

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UTI is rare in young and middle-aged men UTI in men is often associated with catheterization or urological obtruction. bacteriuria in elderly men occurs in  about 10% of those living at home,  about 20% of those living in nursing homes  30% of those who are in-patients in hospitals urinary catheter increases the risk almost ten-fold in hospitalised patients and those in other care homes. pyelonephritis is common in patients who have been catheterised for over a month.

Epidemiology 

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Divide into two types: Catheter associated ( nosocomial) Non-catheter associated (community acquired) Complicated urinary tract infection Uncomplicated urinary tract infection Community acquired UTI is very common in young sexual active women Unusual in men under 50, common among women between 20 and 50 Asymptomatic bacteriuria is more common among elderly men and women ,with rate as high as 40%-50%

“Complicated” or “uncomplicated”? ‘Uncomplicated’ urinary tract infections are  occasional lower urinary tract infections in women with no predisposing factors to infections ‘Complicated’ infections are other UTIs including  pregnant women, men, children  urologic abnormalities, or calculi  catheter-induced infections The investigations and treatment of these patients entail special features

Where are the bugs coming from ????

Etiology/Microbiology 

Gram –negative rods 

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Escherichia coli cause 70% of acute uncomplicated UTI Staphylococcus and saprophyticus account for 10-15% of acute symptomatic UTI in young females Proteus, Klebsiella, enterococcus account for a smaller proportion of uncomplicated UTI

Etiology/Microbiology

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Seratia and pseudomonas play a major role in nosocomial, catheterassociated infections Chlamydia and simplex virus related to sexual activity

Community-Acquired UTI E.coli

S.epi & gm - enterics Enterococcus Proteus K.pneumoniae S.saprophyticus

Nosocomial UTI catheter associated Short Term

Long Term E.coli

Enterococcus

Enterobacter

E.coli

Proteus

Candida Proteus

Providencia Morganella

S.aureus Pseudomonas

Pseudomonas

Pathogenesis Protective mechanisms of urinary tract  Under normal circumstances, bacteria placed in the bladder are rapidly cleared.  Through the flushing and dilutional effects of voiding  The antibacterial properties of the urine and the bladder mucosa  High urea concentration and high osmolarity

Pathogenesis of UTIs 

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Urinary tract infection occurs when bacteria which colonise the anal area ascend through urethra to the bladder Risk factors include 

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reduced resistance offered by the mucous membranes (after menopause) sexual intercourse disturbances in ureteral functioning in children the re-entering of urine back into the ureters (vesicoureteral reflux), which predisposes them particularly to upper UTI’s

Pathogenesis of UTIs 2 Other risk factors:  

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benign prostatic hypertrophy any illness, such as diabetes, which affects the emptying of the bladder spinal injury (associated with disturbances in bladder emptying or urinary catheter) catheterization in hospital or residential care other urological abnormalities receiving immunosuppressive therapy Females with short urethra (4 cm), proximity of the urethra to the anus Use of spermicidal agents

Conditions affecting pathogenesis Gender and sexual activity 

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female prone to colonization with gramnegative bacili because of its proximity to the anus, its short length and its termination beneath the labia sexual intercourse cause the introduction of bacteria into the bladder In men <50 years old, without a history of heterosexual or homosexual rectal intercourse, UTI is uncommon, except for obstrution due to prostate hypertrophy

Acute Uncomplicated Cystitis 

Sexually active young women.

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Causes: anatomy and certain behavioral factors, including delays in micturition, sexual activity, and the use of diaphragms and spermicides tract.

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Aggressive diagnostic work-ups are unwarranted in young women presenting with an uncomplicated episode of cystitis.

Conditions affecting pathogrnesis Obstruction impediment to the free flow of urine such as tumor, structure abnormality, stone and prostatic hypertrophy can cause hydronephrosis and UTI may lead to rapid destruction of renal tissue

Conditions affecting pathogrnesis Pregnancy  about 2%-8% in pregnant women, part of women with asymptomatic will subsequently develop bacteriuria and pyelonephritis  reasons: results from decreased ureteral tone and decreased ureteral peristalsis, or temporary incompetence of the vesicoureteral valves

Conditions affecting pathogrnesis Neurogenic bladder dysfuction  Interference with bladder enervation as in spinal cord injury, multiple sclerosis, diabetes.  May be initiated by use of catheters and is favored by prolonged stasis of urine in the bladder

Conditions affecting pathogrnesis Vesicoureteral reflux  Defined as reflux of urine from the bladder into the ureters and sometimes into the renal pelvis, occurs during vioding or with elevation of pressure in the bladder.  Is common among children with anatomic abnormalitis of the

Anatomic Structure of The kidney •Retroperitoneally on the posterior of the abdomen •11cm long 6cm wide 4cm thick

Conditions affecting pathogrnesis Bacterial virulence factors  Markedly influence the likelihood of infection  Most E. coli cause symptomatic UTI include a small number of specific O,k,and H serogroups  Fimbriae mediate the attachment of bacteria to specific receptors on epithelial cells  E. coli strains usually ptoduce hemolysin and aerobactin and resistant to the bactericidal action of human serum

Fimbriated Bacterial Cell

F = Flagellum Note: All other appendages are fimbriae (a.k.a., pili)

Conditions affecting pathogrnesis Genetic factors  Increasing evidence suggests that host genetic factors influence susceptibility to UTI  A materal history of UTI is more often than among controls  The number and type of receptors on uroepicelial cells to which bacteria may attach are least in part genetically determined the urinary infection

Urinary tract infection

Clincal symptoms

Acute Uncomplicated Cystitis 

Clinical Features: dysuria, frequency, urgency, suprapubic pain, hematuria. 

Fever >38C, flank pain, costovertebral angle tenderness, and nausea or vomiting suggest

Acute Uncomplicated Cystitis 

The microbiology is limited to a few pathogens.

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70%- 85% are caused by Escherichia coli

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5-20%are caused by coagulase-negative Staphylococcus saprophyticus

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5-12% are caused by other Enterobacteriaceae such as Klebsiella and

Clinical presentation Acute pyelonephritis  Symptoms:generally develop rapidly over a few hours or a day,including fever,shaking chills,nausea,vomiting,diarrhea,tachycardia,m uscle tenderness  Physical examination:reveals tenderness on deep pressure in one or both costovertebral angles (between spinal column and the twelfth rib); or on deep abdominal palpation  Urine examination: leukocytosis and bacteria in urine, leukocyte casts, hematuria

Clinical presentation Urethritis  30% of women with acute dysuria,frequency,and pyuria have urine culture that show no significant bacterial growth  Sexually transmitted pathogen, such as C.trachomatis,gonorrhoeae,or herpes simplex virus  History of recent sex-partner change,especially if the partner has recently developed chlamydial urethritis

Clinical presentation Catheter-associated UTI  10%-15% of hospitalized patients with catheters develop bacteriuria  Pathogen:E.coli, proteus,pseudomonas,klebsiella,serratia,staphylococci,e nterococci,and candida  Display markedly antimicrobial resistance than community-acquired UTI  Risk factors:female,prolonged catheterization,severe underlying illness  Cause minimal symptoms and no fever and often resolved after withdraw of the catheter  Treatment should be provided when symptomatic infections arised, but treatment of asymptomatic bacteriuria in such patients has no apparent benefit

diagnosis Diagnostic testing 

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Determination of the number and type of bacteria in the urine is important In symptomatic patients: bacteria counts >105/ml In asymptomatic patients: > 105/ml should be demonstrable in both two consecutive urine specimens or any degree in suprapubic puncture and or >102/ml obtained by catheterization, usually indicates infection

Collecting a sample

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in adults and older children a mid stream urine (MSU) sample usually reliably represents the urine in the bladder. samples collected from urinary bags or bedpans should not be used to diagnose UTI as they invariably will be contaminated the most reliable sample is obtained via a suprapubic puncture urine in bladder >4 hours (any shorter time will increase the risk of false negative findings)

Diagnosis of UTIs 1

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No need to do any urinalysis, urinalysis if a female patient, who does not belong to any of the risk groups, clearly has occasional cystitis based on her symptoms

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Urine microscopy is not necessary to diagnose cystitis

usually

Diagnosis routine Symptomatic patient

Uncomplicated cystitis in a woman, no risk factors not a relapse

Yes

No Bacterial culture, "on the spot" testing to confirm diagnosis

No

Typical symptoms, < 2 infections / year, patient familiar with her illness

Yes

Start treatment based on results

Antibiotic therapy

Diagnosis of UTIs 2

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Bacterial culture of urine should be carried out in all cases, except in uncomplicated cystitis, even though the results will not be available when medication is commenced (B)

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In early pregnancy bacterial culture should be carried out in all pregnant women if only to diagnose asymptomatic bacteriuria (A)

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In adult febrile infections with generalised symptoms, and in children’s infections, C-reactive protein (CRP) CRP concentration above 40 mg/l is suggestive of a kidney infection (C)

diagnosis Diagnostic testing  Microscopy of urine from symptomatic patients can be great diagnostic value  Pyuria is a highly sensitive indicator of UTI in symptomatic patients  Pyuria in the absence of bacteriuria may indicate infection with unusual agents such as trachomatis,mycobacterium,or with fungi  Or in noninfectious urologic conditions such as calculi ,anatomic abnormality, vesicoureteral reflux, interstitial nephritis, or polycystic disease

diagnosis Urologic evaluation  Cystoscopy and intravenous pyelograpy should be taken in women with relapsing infection, a history of childhood infections, stone or painless hematuria, or recurrent pyelonephritis  Most males should be considered to have complicated infection and thus should be evaluated urologically

diagnosis Localization of infection  Unfortunately, currently available methods of distinguishing renal parenchymal infection from cystitis are neither reliable nor convenient enough  Fever or an elevated level of creactive protein often accompanies acute pyelonephritis

Treatment principle 1.Except in acute uncomplicated cystitis in women, a quantitative urine culture or a comparable alternative diagnostic test should be performed before empirical treatment is begun 2.When culture results become available, antimicrobial sensitivity testing should be used to further

Treatment principle 3.Factors predisposing to infection ,such as obstruction and calculi, should be identified and corrected if possible 4.Relief of clinical symptoms does not always indicate infections cured 5.Each course of treatment should be classified after its completion as a failure or a cure 6.In general, uncomplicated infections confined to the lower urinary tract respond to short courses of therapy, while upper tract infection require longer treatment.

Treatment principle 7.After therapy, early recurrences due to the same strain, may result from an unresolved upper tract infection, recurrences>2weeks after the cessation of therapy always represent reinfection with a new strain or with the previously infecting strain that has persisted in the vaginal and rectal area 8.Despite increasing resistance, community acquired infections, especially initial infections are usually due to more antibiotic-sensitive strains

Treatment principle 

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Many have advocated single-dose treatment for acute cystitis,but often be recurrent quickly, and single dose therapy does not eradicate vaginal colonization with E.coli A 3-days course of therapy with (TMP-SMX, norfloxacin, ciprofloxacin, or ofloxacin) are prefered for acute cystitis. If TMP-SMX resistance exceeds 20%, fluoroquinolone and nitrofurantoin can be used Pyelonephritis , urologic abnormalities, stones or previous infection due to antibiotic-resistant organisms, a 7-14 days course of therapy is needed

Treatment principle 

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Acute uncomplicated pyelonephritis, a 7-14 days course of a fluoroquinolone, an aminoglycoside, or a third generation cephalosporin is usually adequate. Complicated UTI,usually due to hospital acquired bacteria, such as E.coli, klebsiella, proteus, serratia, pseudomonas, enterococci, and staphylococci, many of the strains are antibiotic resistant, empirical antibiotic therapy should provide broad spectrum coverage against these pathogens

Antimicrobial therapy in UTIs 1 Acute uncomplicated cystitis: 

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patient with typical symptoms, not belonging to any of the risk groups, is treated without laboratory investigations if the symptoms are atypical, a strip test urinalysis may be carried out to support diagnosis if the strip test is negative, the urine should be cultured and other reasons for the symptoms should be considered

First choices:  trimethoprim for 3-5 days  nitrofurantoin for 5-7 days

Antimicrobial therapy in UTIs 2 Reserve drugs:  Quinolones (norfloxacin, ofloxacin or ciprofloxacin) for 3 days  if first choice drugs are not suitable or  if the infection has not responded to first choice drugs or  recurrent infection within 4 weeks  if there is a relapse, urine must be cultured and the treatment should be continued for 7 days  In special cases:  cefalexin or cefadroxil for 5 days (if the above are contraindicated)  sulphatrimethoprim for 3 days (particularly if the level of infection is unclear)  amoxicillin for 5 days (particularly in enterococcal infections)

Single-dose therapy 

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single-dose therapy is slightly less effective than conventional therapy effective in infections caused by E. coli, coli but less effective in S. saprophyticus infections Preparations:  phosphomycin 3 g  norfloxacin 800 mg  ciprofloxacin 500 - 750 mg  ofloxacin 200 mg as a single dose

Treatment of pyelonephritis

Uncomplicated pyelonephritis: 

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A pyelonephritis patient who is not unduly ill can be looked after at home (C) Treatment with either a fluoroquinolone or sulphatrimethoprim orally for 10-14 days

Treatment of pyelonephritis 2 An unwell pyelonephritis patient with or without high temperature should be admitted to hospital 

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in hospital the treatment is commenced with cefuroxime i.v. 0.75-1.5g every 8 hours or with an fluoroquinolone orally third-generation cephalosporins are usually not recommended for the treatment of uncomplicated pyelonephritis, but ceftriaxone may be chosen as the initial therapy, if either once a day or intramuscular administration are considered beneficial aminoglycosides have shown no additional benefits over other forms of treatment

Treatment during pregnancy Bacteriuria during pregnancy is associated with increased risk of premature labour and pyelonephritis 

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asymptomatic bacteriuria and cystitis are treated in the same way single-dose treatment is not recommended drugs of choice  beta-lactamase (mecillinam, amoxicillin or first-generation cephalosporins) for 5 – 7 days. due to foetal risk fluoroquinolones should be avoided during the whole of pregnancy and sulphatrimethoprim during the latter part of pregnancy

Lower UTIs in children 

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treatment principles are the same as for adults little evidence to support short term treatment in children (C) drugs of choice   

nitrofurantoin 5 mg/kg/day or trimethoprim 8 mg/kg/day treatment to continue for 5 days (C)

UTIs in men 

a UTI in men can be associated with either acute or chronic bacterial prostatitis

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prostatitis or epididymitis may play a part particularly in febrile UTI

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it is advisable to palpate both the prostate and scrotum chronic bacterial prostatitis, or at least the retention of bacteria in the prostatic ducts, should be suspected in relapses with the same causative bacteria

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UTIs in men 2

Afebrile lower urinary tract infection in men: men 

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if the infection is not associated with urinary stricture or prostatitis,it is treated with the same drugs as cystitis in women, but the treatment should continue for 7 10 days nitrofurantoin should not be used in men as adequate prostatic concentrations are not achieved (D)

Febrile urinary tract infection in men is treated with 

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a long course of antibiotics with good prostatic and epididymal penetration first choice: a fluoroquinolone for 2 weeks

UTIs in men 3 UTI in men associated with acute bacterial prostatitis 

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treatment for 4 - 6 weeks (depending how quickly patient responds to treatment) to be followed up with low dose prophylaxis with e.g. trimethoprim or nitrofurantoin

Chronic bacterial prostatitis   

recurrent UTI’s and calcifications in prostate oral quinolones for 2 – 3 months (D) to be followed up with prophylactic medication

Treatment of UTI in diabetics Cystitis in diabetics 

drugs of choice for initial treatment are same as for uncomplicated UTI

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antibiotic treatment must

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treatment to continue for 7 days

always be based on the results of urine culture

Acute pyelonephritis in diabetics 

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treatment is the same as for uncomplicated pyelonephritis consider urological imaging earlier than normal, if there is no response to appropriately chosen medication the causative agents of recurrent UTI’s in diabetics are often unusual, resistant microbes (species of

Antimicrobial therapy in association with a urinary catheter 1 

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the treatment of UTI in a catheterized patient should always be based on the identity and sensitivity of the causative microbe the catheter should always be removed, at least for the duration of treatment, as otherwise the bacteria will not be eradicated if this is not feasible, the recommendation is to continue

Antimicrobial therapy in association with a urinary catheter 3 Fungal bladder infection in a catheterised patient: 

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systemic fluconazole is slightly more effective than topical amphotericin B removal of the catheter will improve the eradication of the microbe during therapy

Suprapubic catheter: 

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its use is associated with a lower incidence of bacteriuria in postoperative care any infections are treated as any other infections associated with urinary

treatment 

Asymptomatic bacteriuria

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In noncatheterized patients is common, especially among elderly patients, but has not been linked to adverse outcomes in most circumstances, thus antimirobial therapy is unnecessary. But patients with high-risk patients with neutropenia, renal transplants, obstruction, or other complicating conditions may require treatment

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Complications  

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Papillary necrosis Risk factors: vascular diseases of the kidney, urinary tract obstruction, diabetes, chronic alcoholism Manifestations: hematuria, pain in the flank or abdomen, chills and fever, acute renal failure, Diagnosis: necrotic tissue pass in the urine, or a “ring shadow” on pyelography

prognosis 

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Uncomplicated cystitis or pyelonephritis, results in complete resolution Cytitis may result in upper tract infection or in bacteremia, but seldom develop renal impairment Repeated upper tract infection will lead to renal dysfunction, a search for renal calculi or urologic abnormality should be taken

prevention 

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Women experience frequent symptomatic UTI (>3 thrice/year), longterm administration of low-dose antibiotics should be given to prevent recurrences Daily or thrice/week administration of a single dose of TMP-SMX, or nitrofurantoin has been particulary effective Women should be advised to avoid spermicide use, and to void soon after sexual intercourse After voiding, wipe from front to back