Bacteriuria in pregnancy

Obstetrical outcome in women with urinary tract infections in childhood

INTRODUCTION

Urinary tract infections (UTI) during childhood can result in permanent renal damage, with possible implications for future pregnancies. The aim of this prospective study was to investigate pregnancy outcomes in women followed after their first UTI in childhood.

MATERIAL AND METHODS

A cohort of 72 parous women was followed from their first UTI in childhood up to a median age of 41 years. Clinical data were obtained from antenatal and hospital records. Renal damage was evaluated by a (99m) Tc-dimercaptosuccinic acid scan. Pregnancy blood pressure (BP), complications and UTIs were compared between women with and without renal damage.

RESULTS

All women completed the investigations, 48 with and 24 without renal damage. No woman, irrespective of presence or absence of renal damage, was diagnosed with hypertension before the first pregnancy. Pregnancy-related hypertension was diagnosed in 10 of 151 pregnancies, all in women with renal damage. Preeclampsia occurred in four women. Women with renal damage had significantly higher systolic BP measured at the last antenatal visit of their first pregnancy, compared with women without renal damage (p = 0.005). During subsequent pregnancies both systolic and diastolic BP were significantly higher in women with than without renal damage (p = 0.02 and p = 0.03, respectively).

CONCLUSION

In this population-based follow-up study we found a large proportion of women with renal damage after UTI in childhood. Women with renal damage had significantly higher BP during pregnancy compared with women without renal damage. Pregnancy-related hypertension was recorded only in women with renal damage. However, pregnancy complications, including preeclampsia, were few.

Asymptomatic bacteriuria and symptomatic urinary tract infections in pregnancy

Symptomatic and asymptomatic bacteriuria is common in pregnant women. A history of previous urinary tract infections and low socioeconomic status are risk factors for bacteriuria in pregnancy. Escherichia coli is the most common aetiologic agent in both symptomatic and asymptomatic infection and quantitative culture is the gold standard for diagnosis. Treatment of asymptomatic bacteriuria has been shown to reduce the rate of pyelonephritis in pregnancy and therefore screening for and treatment of asymptomatic bacteriuria has become a standard of obstetrical care. Antibiotic treatment of asymptomatic bacteriuria is associated with a decrease in the incidence of low birth weight, but the methodological quality of the studies limits the strength of the conclusions that can be drawn. Debate exists in the literature as to whether treated pyelonephritis is associated with adverse fetal outcomes. There is no clear consensus in the literature on antibiotic choice or duration of therapy for infection. With increasing antibiotic resistance, consideration of local resistance rates is necessary when choosing therapy.

Urinary tract infections in pregnancy

Although pregnancy does not increase the prevalence of ASB in women, it does enhance the progression rate from asymptomatic to symptomatic disease. Furthermore, ASB is associated with preterm delivery. Given the fact that identification and eradication of ASB in pregnant women can lower the likelihood of pyelonephritis and prevent preterm delivery, every gravida should be systematically screened for ASB and appropriately treated. In the authors' opinion, a first-trimester urine culture remains the screening test of choice; reliance on symptoms to prompt screening is inadequate because the state of pregnancy can provoke frequency and nocturia. Multiple antibiotic regimens for ASB are safe during pregnancy and effective.

The diagnosis of bacteriuria during pregnancy

Three diagnostic tests, Nitur, Urobact, and Uricult, were evaluated in the detection of bacteriuria in 865 pregnant women. As reference method agar culture was performed. Heavy growth (greater than 10(5) CFU/ml) of urinary tract bacteria was considered a true positive result and demonstrated in 58 (6.7%) of the women, 14 of whom had gram-negative rods. The sensitivity of the nitrite test was extremely low (0.13). The test gave negative results in eight of 17 specimens yielding heavy growth of Escherichia coli or Proteus mirabilis. Although the Urobact test was highly sensitive as regards gram-negative infection, it had an unacceptably low (0.27) predictive value in positive tests. The sensitivity of the Uricult test was low (0.35) in this study. The predictive value (0.50) of a positive test result may be acceptable, since just over half of the false positive results were explainable by moderate growth of urinary tract pathogens (10(4)-10(5) CFU/ml). It is argued that semi-quantitative urine culture may be preferable to the rapid diagnostic methods studied for the screening of bacteriuria in pregnant women.

Socio-biological correlates of bacteriuria in Saudi pregnant women

Prevalence and socio-biological correlates of bacteriuria in Saudi pregnant women were investigated at King Fahd Hospital of the University, Al-Khobar, Saudi Arabia. Midstream sample specimens of urine were used for identification of significant bacteriuria (greater than or equal to 10.5 organisms of single species per milliliter of urine). The prevalence of bacteriuria was found to be 14.2%. It was more common in women below 20 years of age and among the parous as against the nullipara women. Bacteriuria was significantly associated with socio-economic conditions. It was higher in those with a low family income, of large family size (10+) and living in over-crowded conditions. Only one-fourth (25.8%) of bacteriuric women were symptomatic. Almost half (45.8%) had a past history of urinary tract infection. To identify the problem of urinary tract infection in a vulnerable group of women, as well as to reduce the load on laboratory facilities, it is suggested that routine antenatal screening for bacteriuria should be advocated on a selective basis, i.e. for the young teenage parous women, those coming from disadvantaged socio-economic conditions and in patients with a past history of urinary tract infection.

Total and specific immunoglobulin response to acute and chronic urinary tract infections in a rat model

Total and specific levels of immunoglobulins IgG, A and M were determined by an enzyme-linked immunosorbent assay (ELISA) in a rat model of urinary tract infections (cystitis) during the early and late phases of infection. The early response was characterized by rapid rise in IgM in serum and urine. This response decreased rapidly and was undetectable in urine after eight weeks. Correlation between total serum and urine levels of IgM was not found although a chronological relationship was observed. Total and specific serum and urine IgA responses were erratic. Concentrations of IgA were low and this antibody class was undetectable in urine until the infection had been established for six weeks. In contrast, total serum and urine IgG increased in concentration at five days post infection and reached total maximum by weeks four to eight, then declined, but remained detectable over 24 weeks. Specific IgG titers remained elevated in serum but declined in urine between four and 10 weeks. A correlation between total serum and total urine IgG was found. Also, bacteria generated a concomitant nonspecific response, a part of which was detected against a common antigen expressed on E. coli J5 strain that cross-reacts with a number of gram negative genera. The results show that IgM chronologically is the first antibody to appear in increased amounts in the serum and urine, followed by IgG. The data also suggests a relationship exists between total serum IgG and total urine IgG which may affect the host's ability to eliminate urinary infection.

Is screening for bacteriuria in pregnancy worth while?

A total of 4470 pregnant women were screened for bacteriuria by the dipslide method and significant growth found in 226 (5.1%). In 198 cases the urine was re-examined, in 119 by using suprapubic aspiration or catheterisation (62 (52%) samples contained bacteria) and in 79 by using midstream urine samples (26 (33%) samples contained greater than 10(8) colony forming units/1), showing the maximum prevalence of confirmed bacteriuria to be 2.6%. Overt urinary tract infection developed later in four of 80 patients with proved bacteriuria who had been given antibiotics, in one of eight untreated patients with bacteriuria, in one of 110 patients with unconfirmed bacteriuria, and in one of 226 non-bacteriuric controls. A history of urinary tract infection was given by 18% of controls and 42% of women with confirmed bacteriuria. Screening for bacteriuria and treatment with antibiotics to prevent later overt infection is expensive. Whether it is worth while and cost effective depends largely on the prevalence of bacteriuria in the local population and the proportion who develop overt infection. The screening and treatment programme reported here appeared to prevent only six cases of overt infection.

Group B streptococci at delivery: high count in urine increases risk for neonatal colonization

Of 858 pregnant women studied in matched rectal, urethral and urine cultured specimens, 186 (22%) were found to be colonized by group B streptococci (GBS). GBS were detected significantly more often in rectal specimens (159) than in urethral specimens (108) or in urine specimens (64). This is supporting evidence for the gastrointestinal tract as the main habitat of GBS. Of 1786 women whose urine was sampled at delivery, GBS were isolated from 128 (7%), in 22 of whom (1% of the total) GBS were present in quantities greater than or equal to 10(4) colony forming units (cfu)/ml urine. Neonates born to women with greater than or equal to 10(4) cfu GBS/ml urine were apparently at greater risk for neonatal infection, as they were more commonly and more heavily colonized than were the newborns of women with lower quantities of GBS in urine, or if positive urethral or rectal specimens were considered. The incidence of preterm delivery or obstetric infection was not higher among women in whom GBS were isolated in specimens from any of the 3 sites; foetal distress was more common among their children, but not neonatal respiratory or infectious diseases of which the incidence was low and difficult to assess statistically.

Asymptomatic bacteriuria during pregnancy with special reference to group B streptococci

The relationship between significant bacteriuria (SB), i.e. 2 subsequent voided urine specimens with greater than or equal to 10(5) colony forming units (CFU)/ml, and the occurrence of bacteria in the urinary bladder detected by bladder punction, was investigated in asymptomatic pregnant women. From 30 (70%) of the 43 women with SB studied, bacteria were isolated from the urinary bladder. The same bacteria were found in the bladders of all 21 women with Escherichia coli, the one with Klebsiella pneumoniae, and the one with Staphylococcus saprophyticus in midstream urine. Six of 10 patients with group B streptococci (GBS), 1 of 4 patients with Streptococcus faecalis, and none of 5 patients with Staphylococcus epidermidis in voided specimens had bacteria in the aspirated urine. Serotype III was isolated from 8/10 patients with SB caused by GBS. One child born to a woman with GBS SB but no bacteria in the urinary bladder, got early onset septicaemia. The poor predictive value of SB with GBS, S. faecalis and S. epidermidis necessitates the increased use of bladder puncture for diagnosis of true asymptomatic bacteriuria (AB), i.e. AB with bacteria in the urinary bladder. SB with GBS even without bacteria in the urinary bladder, may constitute a threat to the baby's health.

Single-dose amoxycillin in the treatment of bacteriuria in pregnancy and the puerperium--a controlled clinical trial

Ninety obstetric patients with significant bacteriuria were treated randomly with either a single dose of 3 g amoxycillin or with a conventional course of ampicillin over 7 days. Treatment groups were comparable in terms of age, gravidity and socioeconomic status, and the outcome of pregnancy in the two groups did not differ significantly. Cure rates, assessed at 1 week and 6 weeks after treatment, were not significantly different: 88% for single-dose treatment and 84% for conventional treatment. It is concluded that a single dose of 3 g amoxycillin is a safe, effective and acceptable treatment for bacteriuria in pregnancy and the puerperium.

Bacteriuria in pregnancy treated with a single dose of cephalexin

Of 87 women in whom bacteriuria was diagnosed on dip slides at between 9 and 22 weeks gestation only 51 (59%) had true bacteriuria in urine obtained by suprapubic aspiration. A single oral dose of cephalexin (3 g) was given to 37 of these patients, 10 were Indian and none of them had recurrence of infection after treatment, whereas 11 of the 27 (41%) 'indigenous' women again had bacteriuria within 2 weeks of treatment. None of the other 26 patients had recurrent bacteriuria in the pregnancy studied. Success of treatment was not related to renal concentrating ability nor, apart from ethnic group, were there other significant differences between successes and failures. Although single-dose treatment seems to be less effective in pregnancy than in the non-pregnant patients, it is an acceptable method of treatment provided that all treated patients are followed closely to detect those who do not respond and require further therapy.

Quantitative definition of bacteriuria

Quantitative criteria distinguish bacterial infection (or colonization) of the urine from contamination. These criteria depend on the fact that the density of bacteria in infected urine is usually several orders of magnitude higher than the density of bacteria in contaminated urine. Most research on quantitative definitions of infection has concerned Gram-negative rod infections in women. For asymptomatic bacteriuria, the most prevalent urinary tract infection, and for pyelonephritis, a criterion of 1 X 10(5) cfu/ml provides optimal separation of infection from contamination of voided urine. For acute dysuria and frequency, recent evidence supports the use of a colony count of 1 X 10(2) cfu/ml bacteria as the most useful criterion. For the diagnosis of catheter-associated urinary tract infection, the criterion of 1 X 10(5) cfu/ml has been used most commonly, although a lower threshold may be appropriate. Additional investigation is required to determine the most appropriate quantitative definition of infection in this and several other circumstances.

The in vitro activity of ampicillin, amoxicillin, cephalexin, nitrofurantoin, sulphadiazine and trimethoprim against Streptococcus agalactiae isolated from urinary and other infections

The minimum inhibitory concentrations (MIC) for 100 strains of Streptococcus agalactiae varied as follows: ampicillin 0.1 to greater than 1 mg/l, amoxicillin 0.03 to 0.5 mg/l, cephalexin 2 to greater than 16 mg/l, nitrofurantoin 8 to greater than 64 mg/l, sulphadiazine all greater than 500 mg/l and trimethoprim less than 3.9 to greater than 250 mg/l. The MICs of the beta-lactams were not affected by inoculum density. Amoxicillin was 2.5 times as active as ampicillin. Sulphadiazine and trimethoprim acted synergistically, and the average factor of potentiation exceeded 5.9. The growth curves and drug susceptibilities of 19 strains isolated from urine were similar to those of the 81 strains isolated from other sources.

Renal infection and pregnancy outcome

To evaluate the impact of renal infection on pregnancy outcome, we studied a group of pregnant women with asymptomatic renal bacteriuria and another group who had acute pyelonephritis. In 248 women with asymptomatic bacteriuria, infection was localized by the antibody-coated bacteria method. These women were prospectively matched with abacteriuric control subjects and we found no adverse effects of treated renal or bladder infection. Specifically, the number of women with hypertension and anemia in each group was similar, and infants born to these women were comparable regarding perinatal mortality, mean gestational age, and birth weight, as well as indices of maturity. A total of 487 women with acute pyelonephritis were evaluated in a case-control study and observations of the correlation of maternal anemia and pyelonephritis were confirmed. Women with antepartum infection had no increased adverse perinatal outcome; however, in some women with intrapartum infection, pyelonephritis appeared to have initiated premature labor. We concluded that treated renal infection, whether symptomatic or asymptomatic, does not significantly modify pregnancy outcome.

Unconventional bacteria in urinary tract disease: Ureaplasma urealyticum

Bladder-aspirate urine samples (N = 428) were cultured for the presence of fastidious microorganisms. These samples were obtained from 190 patients with urinary tract disease or symptoms suggesting infection of the urinary tract in whom standard bacteriologic investigation had failed to indicate bacterial infection. Ureaplasma urealyticum was recovered alone or in association with other microorganisms from the bladder urine of 75% of patients with reflux scarring and abnormal renal function. Ureaplasma organisms were localized to the upper urinary tract in 80% of patients with bladder counts greater than 10(3) colony-forming units per ml. The results indicate that microorganisms not conventionally associated with urinary tract infection are recoverable from the bladder urine of a high percentage of patients with so-called "sterile pyelonephritis," in which group of patients these microorganisms may contribute to progressive renal disease.

Bacterial endotoxin and impaired fetal development

Small doses of E. coli endotoxin given to pregnant mice on the 13th day of pregnancy caused only a mild maternal illness but induced resorption of approximately half the number of fetuses in each mouse. The remaining live fetuses developed normally and showed no evidence of retarded growth or malformations. The weights of their placentas and maternal spleens increased significantly. Endotoxin given on the 6th day of pregnancy caused a small reduction in fetal weights.