Asymptomatic bacteriuria

1. Dr.Esraa AL-Maini Asymptomatic bacteriuria

2. Asymptomatic bacteriuria (ASB) is defined as persistent bacterial colonisation of the urinary tract without urinary tract symptoms. Asymptomatic bacteriuria (ASB)during pregnancy

3. Incidence • USA: it occurs in 2–10% , with the higher incidence among women of lower socio-economic status. • UK : it occurs in 2–5% of pregnant women.

4. Risks during pregnancy • Increased risk of pyelonephritis among pregnant women with ASB ranges from a risk difference of 1.8% to 28% • Increased risk of preterm birth in women who have untreated ASB compared with women who do not have ASB. The risk difference 2.1% to 12.8%.

5. Diagnosis • Urine culture (midstream) has been used as the reference standard for diagnosis of ASB. • In studies of ASB, a growth of 105 organisms of a single uropathogen per millilitre in a single midstream sample of urine is considered significant(although some tests have used figures such as 104 and 108)

6. When urine culture is used in screening for ASB. • The drawbacks include the time lag: results are not usually available for at least 24 hours, and the cost. • Its advantages are in being able to identify causative organisms and determine antibiotic sensitivities.

7. A number of rapid tests have been evaluated against urine culture , These include: • 1-Reagent strip tests • 2-Microscopic urinalysis • 3-Gram stain with or without centrifugation • 4-Urinary interleukin • 5-Rapid enzymatic (detection of catalase activity) • 6-Bioluminescence assay.

8. Reagent strip tests which test for one or more of the following: • Nitrite, protein ,blood ,leucocyte esterase • Apositive test result is defined as a strip showingany of the following: • More than a trace of protein • More than a trace of blood • Any positive result for nitrite • Any positive result for leucocyte esterase.

9. This has the advantage of being rapid and inexpensive and requiring little technical expertise The sensitivity of reagent strip testing; • When all tests positive ,orWith either test positive the senstivity 50% At best, reagent strip testing will detect 50% of women with ASB.

10. Microscopic urinalysis • This test consists of microscopic analysis of urinary sediment and pyuria is deemed significant with ten cells per high-power field • A sensitivity of 25%, which means that 75% of women with ASB will be missed using this test

11. Gram stain with or without centrifugation • compared with urine culture. A specificity of 7% was reported when urine was centrifuged and considered positive if the same morphotype of bacteria was seen ˃ 6 of 12 high-power fields. In the other study specificity of 89%, urine was not centrifuged and a positive smear was defined as more than two organisms per high-power field. With the low specificity in the more rigorous estimation, more than 90% of women who do not have ASB will be incorrectly identified as cases.

12. Other tests The urinary interleukin-8 test The rapid enzymatic test (detection of catalase activity) both of which have a sensitivity of 70% and will potentially miss 30% of women with ASB. • A bioluminescence test has been described, with a sensitivity of 93% and a specificity of 78 %.

13. . There is controversy around whether to use a dipstick or a culture test for screening. • The culture test is relatively more expensive but has a higher sensitivity and specificity. • Regarded as the gold standard, is not cost beneficial when compared with the dipstick strategy, if preterm birth included its cost benifcial .

14. previous recommendation advising screening for bacteriuria in order to reduce the risk of preterm birth was no longer valid since an update ( no association between treating asymptomatic bacteriuria and reducing the incidence of preterm birth)

15. Out of pregnancy • Antibiotic treatment of ASB does not reduce frequency of symptomatic UTI • Treatment of ASB in diabetes does not reduce adverse outcomes, improve glucose control, or reduce symptomatic UTIs • It does lead to untreatable drug resistant bacteria • Only exceptions are pregnancy ,patients undergoing urologic procedures (such as prostate biopsy)

16. During pregnancy • Antibiotic treatment reduced persistent bacteriuria during pregnancy • Reduced risk of preterm delivery or low-birth weight babies • Reduced the risk of development of pyelonephritis by 30%

17. Treatment: • single-dose antibiotic treatment with a 4 to 7 day course of antibiotic treatment for asymptomatic bacteriuria showed no difference in the prevention of preterm birth pyelonephritis • Longer duration of treatment, however, was associated with increased reports of adverse effects

18. Follow up: Urin culture should be repeated 1 week after completion of therapy and at regular intervals 15-20%will have recurrent bacteriuria during the same pregnancy Recurrent infection by same organism so renal origin treat by 3 weeks coarse ,but different organism is likely to represent bladder infection and can usually be eradicated with short term therapy. Persistent AB despite 2-3 course of treatment 100mg nitrofurantoin daily usually prevent symptomatic infection

19. Take home message; • Women should be offered routine screening for asymptomatic bacteriuria by midstream urine culture early in pregnancy(16weeks). Identification and treatment of asymptomatic bacteriuria reduces the risk of pyelonephritis.

20. Thank you