Asymptomatic bacteruia

1. URINARY TRACT INFECTION &
ASYMPTOMATIC BACTERIURIA IN
PREGNANCY
Dr Menuba ifeanyi.c.e
OBGYN
22nd august 2019

2. Learning Objectives
• Concept of UTI in pregnancy
• Types of UTI
• Diagnosis of UTI and ASB
• Management of UTI and ASB
• Complications/Differential diagnosis

3. Introduction
• Pregnancy predisposes to UTI through
increased urinary stasis:
• as a result of progesterone effect which
reduces smooth muscle tone in the ureters
• Mechanical effect of uterine pressure on the
ureters at the pelvic brim
• It is the commonest indication for antibiotic
therapy in pregnancy

4. Types of Urinary Tract Infections (UTI)
• Asymptomatic Bacteriuria
• Acute Cystitis
• Acute pyelonephritis
• Chronic pyelonephritis

5. Epidemiology of UTI
• Overall, UTIs are 14x more frequent in women
than men
• The following factors are responsible for this
difference:
• Urethra shorter in women
• Lower third of urethra is continuously
contaminated with pathogens from the vagina
and rectum

6. Epidemiology of UTI
• The female urogenital system is exposed to
bacteria during sexual intercourse
• Prevalence of ASB in pregnancy is 2.5-11% as
opposed to 3-8% in non-pregnant women
• 40% of these cases progress to symptomatic
UTI or pyelonephritis.

7. Risk factors of Bacteriuria in Pregnancy
• Indigent patients have a 5-fold increased
incidence
• Doubled risk in women with sickle cell trait
• Diabetes mellitus
• Neurogenic bladder retention
• Previous renal transplant, previous UTI

8. Asymptomatic Bacteriuria
• Asymptomatic bacteriuria is commonly defined
as the presence of more than 100,000 colony
forming units (cfu)/mL of urine in the absence of
symptoms of UTI.
• It is seen in 5-7% of pregnancies
• Untreated asymptomatic bacteriuria is a risk
factor for acute cystitis (40%) and pyelonephritis
(25-30%) in pregnancy.

9. Complications and Effects of ASB on
Pregnancy
• Maternal anaemia
• Premature Labour
• Intrauterine growth retardation
• Recurrent bacteriuria

10. Urine specimen collection
• In all pregnant women, a urine specimen
should be carefully collected for urinalysis and
culture during the prenatal visit.
• The tests will help to identify patients with
ASB as well as other findings such as
glucosuria

11. Urine specimen collection
• For urine collection, a midstream catch is
adequate, provided the patient is given careful
instructions
• Technique is as follows:
• With one hand, spread the labia
• With the other hand, use a towelette to wipe
the urethral meatus downwards towards the
rectum, then discard the towelette

12. Urine specimen collection
• Void the initial portion of the bladder content
into the toilet
• Catch the middle portion of the bladder
content in the sterile collection container,
while keeping the labia spread with the first
hand
• It has however been shown that the cleaning
process does not completely prevent
contamination

13. Urine specimen collection
• If the patient is unable to void, too ill,
extremely obese, or bedridden, a catheterized
specimen should be collected
• Routine catheterization is not recommended
because of the risk of introducing bacteria into
the urinary tract.

14. Urine specimen collection
• Presence of more than one organism in a
culture usually indicates a contaminated
specimen
• Specimen should be sent for evaluation as
soon as possible
• Specimens allowed to sit at room temperature
may have falsely elevated colony counts
• Refrigerate the specimen at 4 degrees
centigrade if it cannot be transported

15. Urinalysis and culture
• Positive results for nitrites, leukocyte esterase,
WBCs, red blood cells (RBCs), and protein
suggest UTI.
• Bacteria found in the specimen can help with
the diagnosis.
• Urinalysis has a specificity of 97-100%, but it
has a sensitivity of only 25-67% when
compared with culture in the diagnosis of
asymptomatic bacteriuria.

16. Urinalysis and culture
• nitrite dipstick testing may be a reasonable
and cost-effective screening strategy for
women who otherwise may not undergo
screening for bacteriuria, as is often the case
in developing countries.
• Counts lower than 100,000 CFU/ml, with 2 or
more organisms, usually indicate specimen
contamination rather than infection

17. Treatment of ASB in Pregnancy
• Depends on culture and sensitivity report
• Empirical antibiotic should target the commonest
organism, commonly Escherichia coli
• Treatment course is usually 10-14 days
• If bacteriuria persists after 2 courses of Rx and for
recurrent positive cultures, continuous ampicillin
500mg, amoxycillin 500mg or cephalexin 500mg
once a day is given throughout prgnancy

18. Acute cystitis
• Acute cystitis involves only the lower urinary
tract;
• It is characterized by inflammation of the
bladder as a result of bacterial or nonbacterial
causes (eg, radiation or viral infection).
• Acute cystitis develops in approximately 1%
of pregnant patients.

19. Acute cystitis
• Signs and symptoms include haematuria,
dysuria, supra-pubic discomfort, frequency,
urgency and nocturia
• These symptoms are often difficult to
distinguish from those due to pregnancy itself
• Acute cystitis is complicated by upper urinary
tract disease ( ie, pyelonephritis) in 15-50% of
cases

20. Acute pyelonephritis
• This is the infection of the upper urinary tract
involving both renal pelvis and renal
parenchyma
• Occurs in 1-2% of pregnant women
• It can be reduced to 0.5% by Rx of ASB
• Commonly caused by E. coli. (80-90% of cases)
• It originates from fecal flora colonizing the
periurethral area, causing an ascending
infection

21. Other organisms causing UTI
• Klebsiella pneumoniae (5%)
• Proteus mirabilis (5%)
• Enterobacter species (3%)
• Staphylococcus saprophyticus (2%)
• Group B beta-hemolytic Streptococcus (GBS;
1%)
• Proteus species (2%) etc

22. Clinical Presentation of Acute
pyelonephritis
• Onset is usually acute, occurring most
commonly in the second and third trimester
• Symptoms include fever (>38.5oC)
• malaise
• loin pain radiating to the groin
• Anorexia, nausea and vomiting
• Dysuria and frequency of micturition

23. Clinical Presentation of Acute
pyelonephritis
• Signs include acute ill-looking, dehydration,
and febrile
• Tachycardia,
• Costovertebral or renal angle tenderness
• Turbid or bloody urine

24. Investigations in Acute Pyelonephritis
• Urinalysis: high specific gravity, proteinuria
• Urine microscopy: leucocytes, red cells, white cell
casts and bacteria
• Bacteriological studies: culture and sensitivity
• Full blood count: may reveal anaemia and
leukocytosis
• Serum biochemistry: may reveal elevated urea
and creatinine and abnormal creatinine clearance
depending on degree of renal parenchymal
damage

25. Differential Diagnosis of Acute
pyelonephritis
• Premature labour
• Placental abruption
• Appendicitis
• Cholecystitis

26. Complications of Acute pyelonephritis
• Endo-toxic shock
• Adult respiratory distress syndrome
• Chronic renal infection
• Effects on pregnancy: Abortions, intrauterine
growth retardation, intrauterine fetal death
and premature labour

27. Treatment of Acute Pyelonephritis
• Admission to hospital
• IV fluids to correct dehydration, and high fluid
intake encouraged
• Close monitoring of pulse, BP, temperature,
uterine contractions and fetal monitoring
• Calories in the form of easily digestible diet
• Analgesics as appropriate
• Broad spectrum parenteral antibiotic

28. Treatment of Acute pyelonephritis
• Cephalexin or the amoxycillin based drugs
may be given while awaiting culture results
• Once patient is afebrile for 24-48 hours, oral
antibiotics are to be started and given for 10-
14 days
• Urine is rechecked to see if it is negative on
culture

29. Treatment of Acute Pyelonephritis
• Three weekly consecutive positive culture
demands antibiotic therapy for the rest of the
pregnancy
• Patients with history of pyelonephritis should
provide midstream specimens of urine for
culture at every subsequent attendance
• Repeated infections require renal tract
investigation three months after delivery

30. Chronic Pyelonephritis
• A chronic process characterized by severe
scarring of the kidneys resulting from
persistent recurrent infections
• Occurs most commonly in patients with
vesico-ureteral reflux
• Antibiotic prophylaxis is given
• Ampicillin 500mg or tab nitro-furantoin
100mg or cephalexin 500mg at night
throughout pregnancy

31. Complications of chronic
pyelonephritis during pregnancy
• Chronic microcytic anaemia refractory to iron
therapy
• Chronic hypertension
• Super-imposed pre-eclampsia
• Hyponatremia if on diuretic therapy

32. Other Differential Diagnosis of UTI
• Cervicitis
• Non-bacterial cystitis
• Ectopic Pregnancy
• Nephrolithiasis
• Vaginitis

33. Prognosis
• In most cases of bacteriuria and urinary tract
infection (UTI) in pregnancy, the prognosis is
excellent. The majority of long-term sequelae
are due to complications associated with
septic shock, respiratory failure etc

34. Prognosis
• Maternal UTI has few direct fetal sequelae
because fetal bloodstream infection is rare;
however, uterine hypoperfusion due to maternal
dehydration, maternal anemia, and direct
bacterial endotoxin damage to the placental
vasculature may cause fetal cerebral
hypoperfusion.
• Untreated upper UTIs are associated with low
birth weight, prematurity, premature labor,
hypertension, preeclampsia and maternal anemia

35. Conclusion
• Asymptomatic bacteriuria (ASB) occurs in 2-15% of
pregnant women, and
• 20-40% of pregnant women with ASB will eventually
develop pyelonephritis later in pregnancy, compared
with 1-2% of women without bacteriuria.
• Pyelonephritis, and possibly ASB alone, can lead to
maternal and perinatal complications during
pregnancy.
• Eradication of ASB with antimicrobials reduces this risk
which has led to recommendations for routine
screening and treatment of ASB in pregnancy.