Limited clinical utility of blood and urine cultures in the treatment of acute pyelonephritis during pregnancy.

OBJECTIVE: The purpose of this study was to determine the utility of urine and blood cultures in the clinical management of pregnant women with acute pyelonephritis. STUDY DESIGN: Data were pooled from three randomized controlled trials that were conducted at two university-based tertiary care centers and included 391 pregnant women with pyelonephritis. The results of urine and blood cultures were correlated with clinical management decisions, outcome, length of hospital stay, and cost. RESULTS: Results of 98% of urine cultures (382/391) and 99% of blood cultures (388/391) were available for analysis. The most common pathogen isolated was Escherichia coli, which was found in 79% of the urine cultures (300/382) and in 77% of the blood cultures (27/35). Susceptibility testing revealed 46% resistance to ampicillin; 7%, 2%, and 0% resistances to first-, second-, and third-generation cephalosporins, respectively; and 1% resistance to gentamicin. Six percent of the participants (25/391) required changes in antibiotic therapy, most commonly for persistent fever (6/25, 25%). Positive blood culture results directly influenced management by prolonging the duration of hospitalization, with means of 4.6 +/- 2.6 hospital days for women with bacteremia and 2.6 +/- 1.5 hospital days for women without bacteremia (P <.001) despite similar durations of symptoms. CONCLUSION: Urine and blood cultures with sensitivity testing had limited utility in the clinical management of pregnant women with pyelonephritis. Decisions to change antibiotic treatment were affected more by clinical course than by culture results. We suggest that elimination of blood and urine cultures might simplify management and result in significant cost savings without compromising patient care.

Rapid enzymatic urine screening test to detect bacteriuria in pregnancy.

OBJECTIVE: To determine the sensitivity, specificity, and positive and negative predictive values of an enzymatic urine screening test for diagnosing bacteriuria in pregnancy. METHODS: Clean-catch midstream urine samples were collected from 383 women who had routine prenatal screening for bacteriuria. Sensitivity, specificity, and positive and negative predictive values for each screening test (enzyme activity, nitrites or leukocytes on dipstick, and bacteria or pyuria on microscopic examination) were estimated using urine culture as the criterion standard. Urine cultures were considered positive if they grew 10(4) colony-forming units of a single uropathogen. Standard deviations used to calculate 95% confidence intervals were based on binomial distribution. A sample of 30 urine specimens was selected to evaluate interrater agreement using Cohen's kappa statistic. RESULTS: Five of 383 samples were contaminated, leaving 378 samples for evaluation. Thirty of 43 specimens with positive urine culture had positive enzyme activity. Of 335 samples with no growth, 150 had negative enzyme activity. Sensitivity, specificity, and positive and negative predictive values for the Uriscreen enzymatic screening test (Bard Patient Care Division, Murray Hill, NJ) were 70%, 45%, 14%, and 92%, respectively. Sensitivity of the Uriscreen was lower than that of bacteria alone. Interrater agreement for Uriscreen testing was high among the three testers (kappa =.86). CONCLUSION: The Uriscreen enzymatic screening test had inadequate sensitivity for rapid screening for bacteriuria in pregnancy.

Fetal membrane distention: determination of the intrauterine surface area and distention of the fetal membranes preterm and at term.

OBJECTIVE: This study was undertaken to obtain an accurate measurement of the intrauterine surface area and the degree of distention of the apposed fetal membranes preterm and at term. STUDY DESIGN: Serial longitudinal images of the uterus in 23 women between 25 and 41 weeks' gestation were obtained by ultrasonography. A Mathematica (Wolfram Research, Inc, Champaign, Ill) program assembled a 3-dimensional image and calculated the intrauterine surface area for each patient. The surface areas of the placental amnion and membranes were measured in vitro after delivery. From these measurements the degree of distention of each fetal membrane in vivo was calculated. RESULTS: The mean calculated intrauterine surface areas were as follows: 1037 +/- 70 cm(2) (25-29 weeks' gestation, n = 4), 1376 +/- 121 cm(2) (30-34 weeks' gestation, n = 4), and 1876 +/- 307 cm(2) (37-41 weeks' gestation, n = 15, P =.0021 by Wilcoxon rank sum test). The surface areas of the expelled membranes at 25 to 29, 30 to 34, and 37 to 41 weeks' gestation were 737 +/- 61 cm(2), 855 +/- 77 cm(2), and 1115 +/- 149 cm(2), respectively. The ratios of intrauterine surface area to the area of the expelled membrane and hence a measure of the degree of distention in vivo were 1.4 +/- 0.05 at 25 to 29 weeks' gestation (n = 4), 1.6 +/- 0.2 at 30 to 34 weeks' gestation (n = 4), and 1.7 +/- 0.3 at term (n = 15). CONCLUSION: The intrauterine surface area in vivo increases during gestation. The surface area of the fetal membranes as measured in vitro increases to a lesser extent. The fetal membranes are therefore distended in vivo.

Outpatient treatment of acute pyelonephritis in pregnancy after 24 weeks.

OBJECTIVE: To compare outpatient to inpatient management of acute pyelonephritis in pregnancy beyond 24 weeks' gestation. METHODS: Ninety-two gravidas past 24 weeks' gestation, randomized to outpatient or inpatient therapy, received two 1-g doses of intramuscular ceftriaxone at 24-hour intervals while hospitalized, then were discharged and reevaluated within 48-72 hours or remained hospitalized until afebrile for 48 hours. Subjects received oral cephalexin after initial treatment. Urine cultures were done on admission and 5-14 days after therapy. Surveillance continued until delivery. We anticipated that 15% of outpatients and 0.01% of inpatients would require changes in antibiotic therapy. RESULTS: Twenty-one percent of women evaluated were excluded. Thirteen of 46 (28%) outpatients' hospitalization exceeded 24 hours. Six outpatients (13.0%) and one inpatient did not respond to initial therapy and were treatment failures (relative risk [RR] 1.82, 95% confidence interval [CI] 1.00, 3.31). Within 2 weeks of initial therapy, seven of 81 (8.6%) subjects had positive urine cultures, four outpatients versus three inpatients (P > .999). Eleven of 84 (13.1%) deliveries for which birth data were available occurred preterm (six of 41 outpatients versus five of 43 inpatients) (RR 1.14, 95% CI 0.61, 2.11). CONCLUSION: There were no significant differences in clinical responses or birth outcomes of inpatients or outpatients treated for acute pyelonephritis after 24 weeks' gestation if they completed their assigned protocols. Thirty percent of outpatients were unable to, and most women with acute pyelonephritis in the third trimester were not candidates for outpatient therapy.

A relaxin-mediated pathway to preterm premature rupture of the fetal membranes that is independent of infection.

OBJECTIVE: This study was designed to show whether the overexpression of relaxin in the decidua of patients with preterm premature rupture of the membranes is independent of or a consequence of chorioamnionitis. STUDY DESIGN: Two experiments were conducted. In the first experiment fetal membranes and decidua were collected from patients with preterm premature rupture of the membranes (n = 17) or preterm labor (n = 17) and were divided according to their degree of histologic infection. Messenger ribonucleic acid was isolated from the tissues and quantitative, sequential Northern analyses were carried out for the expression of human relaxin, interleukin-1beta, interleukin-6, and interleukin-8. The second experiment was aimed at increasing the numbers of messenger ribonucleic acid preparations in the two extreme categories, uninfected and severely infected tissues, with preterm premature rupture of the membranes and preterm labor. Some samples of messenger ribonucleic acid from the first experiment were rerun with the Northern analyses in the second experiment. These repeat samples showed no statistical differences in the results run at different times. Therefore the data from the respective groups of patients in both experiments were pooled for statistical analysis. RESULTS: In both the first experiment and in the pooled data of the two experiments the expression of the relaxin genes was significantly greater (P < .005) in the tissues from patients with preterm premature rupture of the membranes compared with those with preterm labor, in the absence of infection. No effect of the level of infection on the expression of relaxin was noted. In contrast, interleukin-6 gene expression was significantly increased (P < .05) in severely infected tissues, which was independent of whether the delivery was from preterm premature rupture of the membranes or preterm labor. The expression of the interleukin-1beta and interleukin-8 genes were only marginally increased even in severe infection. Marked patient variability in expression of the interleukin genes, especially in severe infection, was noted. CONCLUSION: A relaxin-mediated pathway that leads to preterm premature rupture of the membranes may exist independent of infection.

A randomized trial of three antibiotic regimens for the treatment of pyelonephritis in pregnancy.

OBJECTIVE: To compare the effectiveness of three antibiotic regimens for the treatment of acute pyelonephritis in pregnancy. METHODS: One hundred seventy-nine pregnant women earlier than 24 weeks' gestation who had acute pyelonephritis were randomized to 1) intravenous (i.v.) ampicillin and gentamicin, 2) i.v. cefazolin, or 3) intramuscular ceftriaxone. All participants then completed 10-day courses of oral cephalexin after primary treatment. A urine culture was performed on admission and 5-14 days after completion of therapy. Surveillance for persistent or recurrent infection and obstetric complications continued until delivery. On the basis of a two-sided hypothesis test and with alpha = .025, 60 subjects were needed in each group for statistical power greater than 80% to detect a difference between ceftriaxone and other antibiotics if hospital length of stay differed by 1 or more days. RESULTS: The treatment groups were similar in age, parity, temperature, gestational age, and initial white blood cell count. There were no statistically significant differences in length of hospitalization, hours until becoming afebrile, days until resolution of costovertebral angle tenderness, or infecting organism. There were no statistically significant differences in birth outcomes between the three groups. The average (standard deviation) age at delivery was 38.8 +/- 3.6 weeks. The average birth weight was 3274 +/- 523 g. Eleven (6.9%) of 159 subjects delivered prematurely. Escherichia coli was the most common uropathogen isolated (137 of 179, 76.5%). Blood cultures were positive for organisms in 15 cases (8.4%). At follow-up examination within 2 weeks of initial therapy, eight (5.0%) of 159 subjects had urine cultures positive for organisms. Ten women (6.3%) had cultures positive for organisms later in their antepartum course, and 10 other participants (6.3%) developed recurrent pyelonephritis. CONCLUSION: There are no significant differences in clinical response to antimicrobial therapy or birth outcomes among subjects treated with ampicillin and gentamicin, cefazolin, or ceftriaxone for acute pyelonephritis in pregnancy before 24 weeks' gestation.