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Urinary tract infections


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Published in: Health & Medicine

Urinary tract infections

  2. 2. Introduction  Urinary tract infection (UTI) is a common and painful human illness that, fortunately, is rapidly responsive to modern antibiotic therapy.
  3. 3. Epidemiology and risk factors  Between 1 year and 50 years of age, UTI and recurrent UTI are predominantly diseases of females.  Risk factors  recent use of a diaphragm with spermicide  frequent sexual intercourse,  a new sexual partner,  a UTI in the previous 12 months  a maternal history of UTI  Diabetes  anatomic abnormalities affecting bladder emptying, such as cystoceles, prostatic hypertrophy, urinary incontinence, and residual urine  lack of circumcision  indwelling catheter
  4. 4. Etiology  In acute uncomplicated cystitis  E. coli accounts for 75–90% of isolates;  Staphylococcus saprophyticus for 5–15% (with particularly frequent isolation from younger women);  Klebsiella species, Proteus species, Enterococcus species, Citrobacter species, and other organisms for 5–10%  In complicated UTI  E. coli (predominant organism)  Other aerobic gram-negative rods (such as Klebsiella species, Proteus species, Citrobacter species, Acinetobacter species, Morganella species, and Pseudomonas aeruginosa)  Gram-positive bacteria (e.g., enterococci and Staphylococcus aureus)  yeasts
  5. 5. Pathogenesis  In the majority of UTIs, bacteria establish infection by ascending from the urethra to the bladder. Continuing ascent up the ureter to the kidney is the pathway for most renal parenchymal infections.  Any foreign body in the urinary tract, such as a urinary catheter or stone, provides an inert surface for bacterial colonization. Abnormal micturition and/or significant residual urine volume promotes true infection.  Hematogenous spread accounts for <2% of documented UTIs (caused by relatively virulent organisms, such as Salmonella and S. aureus.)
  6. 6. Pathogenesis of urinary tract infection. The relationship between specific host, pathogen, and environmental factors determines the clinical outcome
  7. 7. Clinical manifestations  Asymptomatic bacteriuria No local or systemic symptoms referable to urinary tract but bacteriuria found incidentally  Cystitis  Dysuria, urinary frequency, urgency  Also nocturia, hesitancy, suprapubic discomfort, gross hematuria may be present.  Unilateral flank or back pain indicates upper urinary tract involvement  Fever indicates involvement of kidney / prostate.
  8. 8. Clinical manifestations  Pyelonephritis High rise, spiking fever with rigor, nausea, vomiting, flank and/or loin pain [Low grade fever in mild cases ]  Rapid rise in creatinine may indicate papillary necrosis.  Intraparenchymal abscess to be suspected when patient has continued fever and/or bacteremia despite antibacterial therapy
  9. 9. Clinical manifestations Emphysematous pyelonephritis associated with production of gas in renal and perinephric tissues in diabetics. Xanthogranulomatous pyelonephritis suppurative destruction of renal tissue from chronic urinary obstruction [e.g. – by staghorn calculi] with chronic infection
  10. 10. Emphysematous pyelonephritis. Infection of the right kidney of a diabetic man by Escherichia coli, a gas-forming, facultative anaerobic uropathogen, has led to destruction of the renal parenchyma (arrow) and tracking of gas through the retroperitoneal space (arrowhead).
  11. 11. Xanthogranulomatous pyelonephritis.A. This photograph shows extensive destruction of renal parenchyma due to long-standing suppurative inflammation. The precipitating factor was obstruction by a staghorn calculus, which has been removed, leaving a depression (arrow). The mass effect of xanthogranulomatous pyelonephritis can mimic renal malignancy. B. A large staghorn calculus (arrow) is seen obstructing the renal pelvis and calyceal system. The lower pole of the kidney shows areas of hemorrhage and necrosis with collapse of cortical areas.
  12. 12. Clinical manifestations  Prostatitis Acute bacterial prostatitis presents with dysuria, frequency, pain in the prostatic, pelvic or perineal area,fever with chill and features of bladder outlet obstruction Chronic bacterial prostatitis presents with recurrent episodes of cystitis
  13. 13. Clinical manifestations  „Complicated’ UTI Symptomatic cystitis or pyelonephritis in a man or a pregnant woman or a non-pregnant woman with an anatomic predisposition to infection, with a foreign body in the urinary tract, or with factors predisposing to a delayed response to therapy.
  14. 14. Diagnosis  In otherwise healthy non-pregnant women diagnosis of cystitis and pyelonephritis can be done on the basis of clinical presentation only!  Otherwise suggestive investigation findings are  positive dipstick test [detects nitrite]  positive leukocyte esterase test  pyuria in routine urine examination  hematuria (in 30% cases)
  15. 15. Diagnosis  Urine culture is the diagnostic "gold standard" for UTI  Identifying specific organism(s) can require time  A colony count threshold of >102 bacteria/mL is very much sensitive (95%) and specific (85%) for the diagnosis of acute cystitis in women.  In men, the minimal level indicating infection appears to be 103/mL.  To diagnose asymptomatic bacteriuria the cutoff is usually 105 bacterial cfu/mL, except in catheter- associated disease, in which case 102 cfu/mL is the cutoff.  Mixed bacterial growth may be due to (i)contamination, (ii) long-term catheterization, (iii) chronic urinary retention, or (iv) the presence of a fistula between urinary tract and gastrointestinal/ genital tract.
  16. 16. Treatment  Uncomplicated cystitis in women The theme is to treat the infection with minimal collateral damage [i.e. adverse ecologic effects of antimicrobial therapy, including killing of the normal flora and selection of drug-resistant organisms.]  Antibiotics that can be used are-  Nitrofurantoin  Trimethoprim-sulfamethoxazole (TMP-SMX)  Fosfomycin  Pivmecillinam  Fluoroquinolones [eg- ofloxacin, ciprofloxacin, levofloxacin etc]  Beta-Lactams
  17. 17. Treatment  Other drugs that may be added  urinary analgesics eg- phenazopyridine  Combination analgesics containing urinary antiseptics (methenamine, methylene blue)  urine-acidifying agent (sodium phosphate),  antispasmodic agent (hyoscyamine)
  18. 18. Treatment  Pyelonephritis  Oral ciprofloxacin 500 mg twice daily for 7 days, (with or without an initial IV 400-mg dose)  Oral TMP-SMX one double-strength tablet twice daily for 14 days (with an initial IV 1-g dose of ceftriaxone if susceptibility unkown)  Combinations of a beta-lactam and a beta-lactamase inhibitor (e.g., ampicillin-sulbactam, ticarcillin-clavulanate and piperacillin-tazobactam) or imipenem-cilastatin in complicated cases.
  19. 19. Treatment  UTI in pregnancy Ampicillin, cephalosporins and nitrofurantoin are considered relatively safe.  UTI in men 7- to 14-day course of a fluoroquinolone or TMP-SMX is recommended. In chronic prostatitis, often warrant a 12-week course of treatment.
  20. 20. Treatment  Complicated UTI Therapy to be individualised according to culture result  Xanthogranulomatous pyelonephritis nephrectomy.  Emphysematous pyelonephritis Early percutaneous drainage and later elective nephrectomy as needed
  21. 21. Treatment  Asymptomatic bacteriuria to be treated in  pregnant women  persons undergoing urologic surgery  neutropenic patients  renal transplant recipients.
  22. 22. Treatment  Catheter associated UTI (CAUTI)  7 to 14 days of antibiotic according to culture report  along with removal/ change of the catheter  “Avoidance is better than cure”  Candiduria  Removal of catheter if any  Drugs that may be used are oral fluconazole (200–400 mg/d for 14 days) oral flucytosine and/or parenteral amphotericin B