Urinary Tract Infections

1. Urinary Tract Infections  Ahmed Al-Sayyad MD,FRCSC

2. Definitions UTI is an inflammatory response of the urothelium to bacterial invasion that is usually associated with bacteriuria and pyuria. Bacteriuria is the presence of bacteria in the urine, which is normally free of bacteria, and implies that these bacteria are from the urinary tract and are not contaminants Pyuria is the presence of white blood cells (WBCs) in the urine and is generally indicative of an inflammatory response of the urothelium to bacterial invasion

3. Definitions Acute pyelonephritis is a clinical syndrome of chills, fever, and flank pain that is accompanied by bacteriuria and pyuria, a combination that is reasonably specific for an acute bacterial infection of the kidney Chronic pyelonephritis describes a shrunken, scarred kidney, diagnosed by morphologic, radiologic, or functional evidence of renal disease that may be postinfectious but is frequently not associated with UTI

4. Definitions Cystitis is inflammation of the bladder, whether used as a histologic, bacteriologic, or cystoscopic description, or a clinical syndrome that is usually accompanied by an abrupt onset of dysuria, increased frequency, urgency, and suprapubic pain. Bacterial cystitis, as opposed to nonbacterial cystitis (e.g., radiation or interstitial), is a useful term.

5. Definitions Uncomplicated UTI is used to describe an infection in a healthy patient with a structurally and functionally normal urinary tract Complicated UTI describes an infection in a patient who is compromised and/or has a urinary tract with a structural or functional abnormality

6. Definitions Recurrent infections are due to either reinfection or bacterial persistence Reinfection is recurrent infection with different bacteria from outside the urinary tract Bacterial persistence refers to a recurrent UTI caused by the same bacteria from a focus within the urinary tract, such as an infection stone or the prostate

7. Definitions Prophylactic antimicrobial therapy is the prevention of reinfections of the urinary tract by the administration of antimicrobial drugs Suppressive antimicrobial therapy is the suppression of a focus of bacterial persistence that cannot be eradicated

8. Classification isolated infections unresolved infections recurrent UTIs that are reinfections recurrent infections resulting from bacterial persistence.

9. Isolated infections First infection or the one isolated from previous infections by at least 6 months occurs in 25% to 30% of women between the ages of 30 and 40 years occurs infrequently in men with a normal urinary tract

10. Unresolved Bacteriuria during Therapy indicates that the initial therapy has been inadequate which could be due to: Resistant to the antimicrobial agent selected to treat the infection Development of resistance in a previously susceptible bacteria during the course of treatment Presence of a second unsuspected species that is resistant to the antimicrobial agent selected

11. Unresolved Bacteriuria during Therapy Rapid reinfection with a new, resistant species before the completion of therapy for the original infecting organism Azotemia, in which diseased kidney cannot achieve adequate concentrations of the antimicrobial agent Giant staghorn calculi who have a huge mass of bacteria that exceeds the antimicrobial activity of the urine

12. Recurrent Urinary Tract Infections The term recurrent urinary tract infection applies either to reinfection from outside the urinary tract or to bacterial persistence in a focus within the urinary tract More than 95% of all recurrent infections in females are reinfections of the urinary tract Reinfections in men are uncommon unless associated with an underlying abnormality of the urinary tract

13. Bacterial Persistence

14. Incidence and Epidemiology UTIs are more common in women than in men except in the neonatal period Symptomatic UTI affects 30% of women between the ages of 20 and 40 years, a prevalence that is 30 times more than in men The overall prevalence of bacteriuria has been estimated at 3.5%(treat in pregnancy)

15. Incidence and Epidemiology Bacteriuria is present in about 1% of schoolgirls (aged 5 to 14 years) With increasing age, the ratio of women to men with bacteriuria progressively decreases At least 20% of women and 10% of men older than 65 years have bacteriuria Prevalence of bacteriuria also increases with institutionalization or hospitalization and concurrent disease

16. Routes of Infection Routes of Infection:Most bacteria enter the urinary tract from the fecal reservoir via ascent through the urethra into the bladder Hematogenous Route:uncommon in normal individuals but occasionally kidneys get secondarily infected in patients with Staphylococcus aureus bacteremia from oral sites or with Candida fungemia Lymphatic Route:Direct extension of bacteria from the adjacent organs via lymphatics may occur in unusual circumstances such as a severe bowel infection or retroperitoneal abscesses

17. Urinary Pathogens E. coli is by far the most common cause of UTI, accounting for 85% of community-acquired and 50% of hospital-acquired infections Other gram-negative Enterobacteriaceae including Proteus and Klebsiella, and gram-positive E. faecalis and Staphylococcus saprophyticus are responsible for the remainder of most community-acquired infections

18. Urinary Pathogens Complicated or nosocomial infections are frequently caused by E. coli and E. faecalis as well as by Klebsiella, Enterobacter, Citrobacter, Serratia, Pseudomonas aeruginosa, Providencia, and S. epidermidis Patients with diabetes are more likely to have urinary tract infections caused by Klebsiella, group B streptococci and non� albicans Candida S. saprophyticus is now recognized as causing approximately 10% of symptomatic lower UTIs in young, sexually active females whereas it rarely causes infection in males and elderly individuals

19. Diagnosis Urine can be collected by the following: suprapubic aspiration,catheterization,voided urine and bagged urine Indirect dipstick tests for bacteriuria (nitrite) or pyuria (leukocyte esterase) are informative but are less sensitive than microscopic examination of the urine When suspected urinalysis for bacteriuria, pyuria, and hematuria should be performed

20. Urine Culture Urine must be refrigerated immediately on collection and should be cultured within 24 hours of refrigeration. Most people agrees that bacterial cfu count of 105/ml is considered positive but this number is fraught with two limitations 20% to 40% of women with symptomatic UTIs present with bacteria counts of 102 to 104 cfu/ml of urine

21. Urine Culture Thus, in dysuric patients, an appropriate threshold value for defining significant bacteriuria is 102 cfu/ml of a known pathogen The second limitation of the 105 cutoff is overdiagnosis. Women susceptible to infection often carry large numbers of pathogenic bacteria on the perineum that contaminate otherwise sterile bladder urine

25. Uncomplicated Cystitis 25% to 30% of women between the ages of 20 and 40 years have had cystitis In women with acute cystitis;causing organisms are E. coli in 80%, and S. saprophyticus in 5% to 15% . Other organisms less commonly involved include Klebsiella species, P. mirabilis, or enterococci. In men, E. coli and other Enterobacteriaceae are the organisms most commonly identified.

26. Uncomplicated Cystitis Clinical symptoms include dysuria, frequency, urgency, voiding of small urine volumes, and suprapubic or lower abdominal pain Hematuria or foul-smelling urine may develop. On examination, suprapubic tenderness may be present

27. Laboratory Diagnosis The presumptive laboratory diagnosis of acute cystitis is based on microscopic urinalysis that indicates bacteriuria, pyuria, and hematuria Urine culture remains the definitive test, and, in symptomatic patients, the presence of 102 or more cfu/ml of urine usually indicates infection

28. Laboratory Diagnosis In women with symptoms and signs of cystitis, no complicating factors are present and got positive urinalysis, urine culture may be omitted A urine culture should be obtained, however, for women in whom symptoms and urine examination findings leave the diagnosis of cystitis in doubt,in women with recent antimicrobial therapy, UTI symptoms for greater than 7 days, age older than 65 years, diabetes, pregnancy and in all men.

29. Management TMP-SMX and TMP are the optimal choices for empirical 3-day therapy for uncomplicated cystitis in young women when TMP resistance to these drugs is less than 20% In women with uncomplicated cystitis, fluoroquinolones should be used primarily for treatment failures, allergies to other drugs, recurrent infections, and infections caused by strains known to be resistant to other antimicrobials,when TMP resistance is 20% or greater Young healthy men should be treated with a 7-day regimen of TMP-SMX, TMP, or a fluoroquinolone

32. Acute Pyelonephritis Although defined as inflammation of the kidney and renal pelvis, the diagnosis is clinical classic presentation is an abrupt onset of chills, fever, and unilateral or bilateral costovertebral angle tenderness These so-called upper tract signs are often accompanied by dysuria, increased urinary frequency, and urgency

33. Acute Pyelonephritis It may also simulate gastrointestinal tract abnormalities with abdominal pain, nausea, vomiting, and diarrhea On physical examination, there is frequently tenderness to deep palpation in the costovertebral angle Blood tests may show leukocytosis, increased ESR, elevated C-reactive protein, positive blood cultures Urine analysis usually shows increased WBCs, WBC casts, and red blood cells Urine cultures are positive, but about 20% of patients have urine cultures with fewer than 105 cfu/ml

34. Acute Pyelonephritis E. coli, accounts for 80% of cases Klebsiella, Proteus, Enterobacter, Pseudomonas, Serratia, and Citrobacter, are also cultured from the urine Of the gram-positive organisms, only E. faecalis and, less commonly, S. aureus and S. epidermidis are important causes of pyelonephritis

36. Imaging IVP may show Focal or generalized renal enlargement,occasionalley delayed contrast excretion,cortical striations and pelvicaleceal dilations if there is an obstruction Renal ultrasonography is useful to show renal size and collecting system obstruction CT is not indicated unless the diagnosis cannot be established or if the patient does not respond after 72 hours of therapy

42. Treatment Infection in patients with acute pyelonephritis can be subdivided into: Uncomplicated infection that does not warrant hospitalization Uncomplicated infection in patients with normal urinary tracts who are ill enough to warrant hospitalization for parenteral therapy Complicated infection associated with hospitalization, catheterization, urologic surgery, or urinary tract abnormalities

43. Treatment The duration of therapy for acute uncomplicated pyelonephritis generally should be 7-10 days for a fluoroquinolone or 14 days for TMP-SMX Patients with complicated pyelonephritis and positive blood cultures should be treated for 7 days with parenteral therapy(aminoglycoside with or without ampicillin, Fluoroquinolones or third-generation cephalosporins are also effective)

44. Treatment If blood cultures are negative, 2- to 3-day parenteral therapy is sufficient then oral therapy should be continued for an additional 7 to 14 days Repeat urine cultures should be performed 5 to 7 days after initiation of therapy and 4 to 6 weeks after discontinuation of antimicrobial therapy to ensure that the urinary tract remains free of infection.

45. Treatment If symptoms persist beyond 72 hours,the possibility of perinephric or intrarenal abscesses, urinary tract abnormalities, or obstruction should be considered and radiologic investigation with ultrasonography or CT performed

48. TB of the urinary tract WHO estimates that one third of the world's population is infected with Mycobacterium tuberculosis and there are 8 to 10 million new active cases of TB each year GU TB accounts for only 7% of extrapulmonary cases in the United States 15% to 20% of TB patients in the developing countries are found with M. tuberculosis in the urine

49. TB of the urinary tract Almost all M . tuberculosis infections are acquired by the inhalation of aerosolized droplet nuclei which reach the pulmonary alveoli Genitourinary TB is usually caused by metastatic spread of organisms through the blood stream during the initial infection Later, active disease results from the reactivation of that initial infection, probably owing to failure of the local immune response.

50. Pathology TB may affect any organ in the GU tract Caseating granulomas develop and consist of Langhans giant cells surrounded by lymphocytes and fibroblasts The healing process results in fibrous tissue and calcium salts being deposited, producing the classic calcified lesion The fibrous tissue may cause strictures anywhere in the collecting system

51. Pathology Tuberculous ureteritis is always an extension of the disease from the kidney. The site most commonly affected is the ureterovesical junction Bladder lesions are without exception secondary to renal TB(bulbous granulations,ulcer,fibrous contracture) TB of the testis is almost always secondary to infection of the epididymis and may lead to orchitis and atrophy

52. Pathology TB of the prostate is rare, and in many cases it is diagnosed by the pathologist or is found incidentally after a transurethral resection. Transmission of genital TB from male to female is very rare TB of the penis and urethra are very rare

53. Clinical Features Genitourinary TB is considered in patients presenting with vague, long-standing urinary symptoms for which there is no obvious cause Males predominats over females 2:1 Most patients are aged 20 to 40 years Genitourinary TB is very uncommon in children

54. Clinical Features Patients usually complain of frequent painless micturition,gross hematuria in 10% of patients and microscopic in 50% Hematospermia is a rare presenting symptom Recurrent cystitis is also a warning sign In a few patients, the only presenting symptom is a painful testicular swelling

55. Diagnosis Tuberculin Test Sterile pyuria" is the classic urinary finding on routine urinalysis At least three, but preferably five, consecutive early morning specimens of urine should be cultured Radiography

56. Diagnosis Plain x-ray may show calcification in the renal areas and in the lower genitourinary tract IVP may show distortion of a calyx, severe calyceal and parenchymal destruction, dilatation above a ureterovesical stricture or, if the disease is more advanced, by a rigid fibrotic ureter with multiple strictures, small and contracted bladder