This pregnant patient is suffering from acute cystitis and is appropriately treated with nitrofurantoin. In pregnant patients, if urinalysis is found to be positive, urine culture should be sent in addition to initiating antibiotics.
Urine culture is necessary in order to assess the sensitivity of the infecting organism to the prescribed antibiotics; this allows for antibiotic therapy to be adjusted to the most effective agent. Due to the physiologic changes associated with pregnancy, including urinary retention, ureteral dilation, and increased urinary tract volume, pregnant patients are at an increased risk of acquiring and developing severe complications from urinary tract infections. In pregnant patients, pyelonephritis requires hospital admission and intravenous antibiotic treatment. However, asymptomatic bacteriuria and cystitis may be managed with oral antibiotic therapy.
Colgan et al. discuss the treatment of asymptomatic bacteriuria in pregnant patients. All pregnant patients should be screened for asymptomatic bacteriuria in the first trimester. If the screening results are positive, potential antibiotic treatment options may include nitrofurantoin, amoxicillin, amoxicillin/clavulanate, ampicillin, cefuroxime, or cephalexin.
Unlo et al. review the most common urinary pathogens and most effective antimicrobial agents for pregnant patients suffering from urinary tract infections. They found that E. coli (82.2%) and Klebsiella (11.2%) were the most common pathogens found on urine culture. They recommend fosfomycin as a first-line treatment option, given the high sensitivity of E. coli (98-99%) and Klebsiella (88-89%) to this antibiotic.
Figure A is a urine microscopy showing numerous white blood cells as well as several bacilli bacteria. Illustration A shows potential antibiotic regimens for the treatment of urinary tract infections in pregnant patients.
Answer 1: TMP-SMX is a class C drug, whereas nitrofurantoin is a class B medication; switching to this new medication would not be warranted.
Answer 2: There is widespread resistance to penicillin; therefore, addition of this medication would not be beneficial.
Answer 3: Self-catheterization does not have a role in the treatment of uncomplicated cystitis in a pregnant patient; in fact, it may increase the risk of bacterial contamination of the urinary tract.
Answer 5: Although nitrofurantoin may be discontinued in favor of another medication after results of urine culture are returned, this antibiotic should be continued at this juncture, as it is the best empiric treatment for this patient's UTI.
Colgan R, Nicolle LE, McGlone A, Hooton TM. Asymptomatic bacteriuria in adults. Am Fam Physician. 2006 Sep 15;74(6):985-90.
PMID:17002033 (Link to Abstract)
Unlu BS, Yildiz Y, Keles I, Kaba M, Kara H, Tasin C, Erkilinc S, Yildirim G. Urinary tract infection in pregnant population, which empirical antimicrobial agent should be specified in each of the three trimesters? Ginekol Pol. 2014 May;85(5):371-6.
PMID:25011219 (Link to Abstract)