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URINARY TRACT INFECTIONS IN PREGNANCY

Table 2. Common antibiotic choices for UTI in pregnancy¹

Antibiotic	Recommended dosage	Pregnancy Risk category
Nitrofurantoin	50 to 100mg 6 hourly	B
Cephalexin	250mg 6 hourly	B
Ampicillin	250mg 6 hourly	B
Amoxycillin-	250mg 6 hourly	B
clavulanic acid Amoxycillin	500mg 8 hourly	B
Trimethoprim-sulfamethoxazole	160mg 12 hourly	C

Category B: Animal studies do not demonstrate foetal risk but no controlled study in humans.  Category C: No controlled study in humans available, animals' study revealed adverse foetal effects.

For acute pyelonephritis in pregnancy, hospitalisation is often indicated even though it is not mandatory. It is easier to monitor for complications if the mother is treated as an in-patient. Indications for admissions include severe distress, dehydration, poor oral food tolerance, maternal and foetal complications and where intravenous antibiotic is necessary. Urine culture and sensitivity is mandatory in the management of acute pyelonephritis, and this should be obtained before starting antibiotics. Empirical treatment with parenteral antibiotics should begin as soon as possible. The clinical condition must be closely monitored for any complications. Antibiotic of choice is based on common aetiology and resistance pattern in the community. When results of the culture and sensitivity are available, the treatment regime can be altered accordingly. E. coli is the major causative agent in acute pyelonephritis. With good hydration and antibiotic treatment, most patients respond within 24-48 hours. If patient's symptoms persist despite appropriate antibiotics, further investigations are needed to evaluate the possibility of underlying predisposing factors such as renal calculi and renal tract abnormalities or a perinephric abscess formation. The latter needs surgical drainage. Septicaemia is present in about 15% of patient with acute pyelonephritis. Blood culture and sensitivity should be obtained if the patient does not respond to antibiotic treatment.3  Intravenous antibiotic therapy should be continued for a further 24-48 hours after initial  response,  evidenced by subsiding fever, disappearance of lumbar pain and improvement in patient's general physical appearance. Oral antibiotics are preferably continued for further 1-2 weeks.3

Group B streptococcal (GBS) vaginal colonisation is proven to be associated with pre-term premature rupture of membranes, neonatal sepsis and congenital pneumonia. This organism also contributes to 5% of UTI. Studies have shown that pregnant mothers who received penicillin treatment for GBS bacteriuria have significantly lower incidence of pre-term delivery and premature rupture of membranes. It therefore make sense that mothers with GBS bacteriuria should be treated with antibiotics.

UTI recur in 4-5% of pregnancies especially when the inital infection is adequately treated. Pregnant mothers with urinary tract calculi, diabetes mellitus and a past history of UTI are more prone to recurrence. Prophylactic antibiotics with cephalexin and nitrofurantoin are effective treatment. Further evaluation of urinary tract abnormalities with radiological imaging is recommended at 3 months postpartum after anatomical and physiological changes of pregnancy have resolved.3

CONCLUSION

UTI  in pregnancy is associated with significant morbidity for both mother and baby. All pregnant mothers should be screened for UTI. Untreated UTI will lead to pre-term premature rupture of membrane, maternal chorioamnionitis, intrauterine growth retardation and low birth weight baby.  Early treatment with antibiotics has significantly reduced the above complications. Urine culture and sensitivity remain the gold standard in diagnosing UTI. If patients' condition are not improving despite adequate and appropriate use of antimicrobials, further investigations for underlying predisposing factors are necessary. Prophylactic antibiotic is indicated for recurrent UTI.

References

1. Delzell JE, Lefevre ML. Urinary tract infections during pregnancy. Am Fam Physician. 2000;61(3):713-21 [PubMed] [Full text]
2. Orenstein R, Wong ES. Urinary tract infections in adults. Am Fam Physician. 1999;59(5):1225-37 [PubMed] [Full text]
3. Gabbe. Infection of the urinary tract. Chapter 40 in Gabbe: Obstetrics-Normal and problem pregnancies. 4th ed. Churchill Livingstone. 2002:1067-70
4. Vazquez JC, Villar J. Treatments for symptomatic urinary tract infections during pregnancy. Cochrane Database Syst Rev. 2003;(4):CD002256. [PubMed]
5. Fitzgerald MA. Urinary tract infection: providing the best care. Medscape, 2002. http://www.medscape.com/viewarticle/436592 [Full text]
6. O'Donnell JA, Gelone SP, Abrutyn E. Selecting drug regimens for urinary tract infections: Current recommendations. Infections in Medicine. 2002;19(1):14-22 [Abstract]
7. Romero R, Oyarzun E, Mazor M, et al. Meta-analysis of the relationship between asymptomatic bacteriuria and pre-term delivery/low birth weight. Obstet Gynecol. 1989;73(4):576-82 [PubMed]
8. Bachman JW, Heise RH, Naessens JM, et al. A study of various tests to detect asymptomatic urinary tract infections in an obstetric population. JAMA. 1993;270(16):1971-4 [PubMed]
9. McGladdery SL, Aparicio S, Verrier-Jones K, Roberts R. Outcome of pregnancy in an Oxford-Cardiff cohort of women with previous bacteriuria. QJM. 1992;83(303):533-9 [PubMed]
10. Uncu Y, Uncu G, Esmer A, Bilgel N. Should asymptomatic bacteriuria be screened in pregnancy? Clin Exp Obstet Gynecol. 2002;29(4):281-5 [PubMed]