1. Urinary tract infection 尿路感染
方 炜
Renal Division, Renji Hospital
Shanghai Second Medical University

2. Introduction
Urinary tract infection (UTI) is the most common of all bacterial infections, affecting humans throughout their life span.
Not only is UTI common, but the range of clinical effects it can produce is exceptionally broad, from acute pyelonephritis with gram- negtive sepsis to asymtomatic bacteriuria.

3. Introduction UTI upper pelvic 肾盂 calyx 肾盏 ureter 输尿管 Female:male 10:1
lower bladder 膀胱 urethra 尿道
pyelonephritis cystitis urethritis
Female:male
10:1

4. Definition
UTI: a broad term that encompasses both asymptomatic microbial colonization of the urine and symptomatic infection with microbial invasion and inflammation of urinary tract structures.
Acute pyelonephritis (急性肾盂肾炎): a pyogenic, focal infection of the renal parenchyma accompanied by local and systemic symptoms of infection.
Chronic pyelonephritis（慢性肾盂肾炎）: the pathologic and radiologic findings of chronic cortical scarrings, tubulointerstitial damage, and deformity of the underlying calyx.

5. Pathogen Gram-negtive enterobacteria is most common 95%
E.coli大肠杆菌 %
Proteus mirabilis 变形杆菌
Klebsiella sp克雷伯杆菌
Pseudomonas sp 绿脓杆菌 (urinary tract instrumentation)
Serratia sp 沙雷杆菌
Gram-positive organisms 5-10%
Streptococcus faecalis 粪链球菌
Staphylococcus aureus 金黄色葡萄球菌
Staphylococcus albus 白色葡萄球菌
Fungi 真菌
Yeasts 原虫
Viruses 病毒

7. Possible routes of infection
Ascending infection
Most UTI are believed to occur by the ascending route.
urethra→bladder→ureter→pelvis→calyx →parenchyma
Hematogenous infection Relatively rare
Staphylococcal bacteremia 金葡菌血症
Intestine to kidney by way of lymphatics
盆腔器官炎症 阑尾炎 结肠炎
Direct infection
外伤 肾周器官感染

8. Ascending infection： urethra→bladder→ureter→pelvis→calyx →parenchyma
Hematogenous infection：
circulation → parenchyma →calyx →pelvis

9. The defence mechanism of urinary tract
Valve at the junction of ureter and bladder.
The dilution and removal of bacteria in urine which occurs with micturition.
The high concentration of urea and low pH in urine restrict the growth of bacteria.
Antibacterial ability of mucosa: secret IgA, IgG.
Prostatic fluid

10. Factors predisposing to infection
Obstruction to the flow of urine anywhere from the kidney to urethra is well recognized as the most important predisposing cause.
Congenital abnormalities such as polycystic kidney disease 多囊肾, vesicoureteral reflux 膀胱输尿管返流.
urinary tract instrumentation
Female urethra
Disturbence of immune capacity such as diabetes, anemia, chronic hepatic disease, chronic kidney disease, tumor and so on.
Inflammation of near area
Other factors

11. Pathology - Acute Phase
Macroscopic examination:
Mucosa is edematous and congestive, and contain a variable number of abscesses on the capsular surface and on cut sections of the cortex and medulla.
Occasionally, areas of inflammation extend from the cortex into the medulla in the shape of wedge.

12. Pathology - Acute Phase
Histologic changes:
Tubular epithelial cells are edematous, necrosis and detach from basement membrane.
Some tubules are damaged and others are destroyed, many tubules contain leukocytes.
Acute inflammation with polymorphonuclear leukocyte infiltraton may be found.
The glomeruli and blood vessels are relatively free of inflammatory changes.

13. Pathology - Chronic Phase
Macroscopic examination:
Parenchymal scarring and underlying caliceal deformity.
The kidneys are frequently irregular, and reduction in size is often unilateral or asymmetrical.
The kidney usually has flat-based or U-shaped scars.

14. Chronic pyenephritis. Note the irregularly scared kidney, dilated and blunted calices.

15. Chronic pyenephritis
broad scars in a patient with chronic VUR.

16. Pathology - Chronic Phase
Histologic changes:
increase in interstitial fibrous tissue
tubule atrophy and necrosis
periglomerular fibrosis

17. Clinical presentations
Acute pyelonephritis
Systemic symptoms: rigors and high fever, often with fatigue, nausea and vomiting, abdominal pain or diarrhea.
Local manifestations: Dysuria frequancy, and nocturia. Back and loin pain (with exquisite tenderness on percussion of the costovertebral angle).
Urine: Cloudy urine, pyuria.

18. Clinical presentations
Chronic pyelonephritis
Asymptomatic bacteriuria, dysuria and frequency, vague complaints of flank or abdominal discomfort, and intermittent low-grade fevers.
May be divided into the following five types: Recurrent type; Low-grade fever type; Hematuria type; Insidious type; Hypertension type

19. Recurrence clinical characteristic of pyelonephritis Relapse:
If bacteriuria recurs with the same pathogen within a short time following cessation of therapy, the recurrence is defined as a relapse.
Reinfection:
infection with new organism.

20. Complications Papillary necrosis Perinephric abscess Septicemia
Renal stone and obstruction

21. Complications- Papillary necrosis
An uncommon complication in pyenephritis.
Occurs more often in diabetic patients.
Patients sometimes have renal colic with hematuria due to passage of papillae down the ureter.
The IVP may show loss of papillae.

22. Complications- Perinephric abscess
rare complication of pyelonephritis, often associated with obstruction to urine flow or DM .
Symptoms and signs: loin pain accentuated by movement, chills and fever, urinary frequency and dysuria.
Ultra-sound, radiation examination help to diagnosis.

25. Laboratory examinations
Urinary routine
White cells are frequently observed.
Detection of leukocyte casts is also an indication of involvement of the kidney.
hematuira
Proteinuria, < 2g/d, low molecular protein.
Low gravity, high pH, when the tubular dysfunction occurs.

26. Laboratory examinations
Gram’s stain
The simplest method for detecting significant bacteriuria is to examine the urine under the microscope, using Gram’s stain.
If bacteria are found using the oil immersion objective, there are likely to be more than 105 bacteria/ml of urine.

27. Laboratory examinations
clean mid-stream urine culture
The most widely used method of collecting urine for culture and is the method of choice.
If the bacterial counts > /ml, can be defined significant result.
When bacterial count < 10000/ml, can be regard as contaminated.
Coccus count reaches 1000~10000/ml also can be defined significant result.

28. Clean mid-stream urine culture, notice:
the procedure should be done before antibiotic therapy or 5 days after cessation antibiotic therapy.
the first uriation is preferred for the bacteria can grow more.
strict attention to asepsis is necessary.

29. Other examinations Blood routine test: WBC，ESR  ，CRP 
Antibody-coated bacteria: help to distinguish pyelonephritis from the lower UTI
Renal function tests: defect in urinary concentrating, acidification capacity as well as glomerular filtration function.
Radiologic evaluations

30. Radiologic evaluations
objective: delineate abnormalities that would lead to changes in the medical or surgical mangement of the patient.
Indication: recurrence; complicated UTI; clinical presentation of pyelonephritis; rare pathogen infection; persistent infection; male
Notice: should be avoided during acute phase

32. Diagnosis Acute pyelonephritis
The diagnosis can be established according to the systemic, local symptoms and signs as well as the urine test.

33. Diagnosis History exceed half year, companied with:
IVP show the deformity and stricture of pelvis and calices
The kidneys are irregular, often asymmetrical
Decreased tubular ability.

34. Differential diagnosis
Lower UTI: Antibody-coated bacteria(-)
urine culture after bladder sterilized
absence of systemic symptom
Urethral syndrome: urine culture(-)
Renal TB: dysuria, frequency and nocturia persistent
and obvious
urine TB culture(+)
serous anti-TB antibody(+)
X-ray

35. distinguished from chronic glomerulonephritis
Chronic glomerulonephritis
Chronic pyelonephritis
History
Edema, hypertension
Usually no edema
Proteinuria
Middle and large molecular protein, usually > 2g
Low molecular protein, usually < 2g
Renal function
Defect of glomerular function
Defect of tubular function
Radiological examination
Sizes of kidneys are similar, no deformity and stricture of pelvis and calices
Sizes of kidneys are different, with deformity and stricture of pelvis and calices

36. Treatment Acute pyelonephritis
General treatment: rest in bed, increase fruid intake and so on.
Antibiotic treatment: should start antibiotic therapy immediately after urine collection. Serious patient should be given combined 2 antibiotic drugs and the drug should be given through intravenous route. The antibiotic course usually is 10~14 days.

37. Treatment Chronic pyelonephritis General treatment:
the most important effort should be made to correct the underlying complicating factors such as urinary tract obstruction, congenital abnormality and so on.
Rest, fruid intake to increase urine volume is also needed.

38. Treatment Chronic pyelonephritis
Principles of antibiotic treatment including:
combined antibiotic therapy is usually need.
treatment course: 2~4 weeks.
correct the underlying complicating factors.
the treatment of acute phase is similar to acute pyelonephritis

39. Thank you