Prevalence of urinary tract infection in febrile infants

Urinary tract infection (UTI), a relatively common cause of fever in infancy, usually consists of pyelonephritis and may cause permanent renal damage. This study assessed (1) the prevalence of UTI in febrile infants (temperature > or = 38.3 degrees C) with differing demographic and clinical characteristics and (2) the usefulness of urinalysis in diagnosing UTI. We diagnosed UTI in 50 (5.3%) of 945 febrile infants if we found > or = 10,000 colony-forming units of a single pathogen per milliliter in a urine specimen obtained by catheterization. Prevalences were similar in (1) infants aged < or = 2 months undergoing examination for sepsis (4.6%), (2) infants aged > 2 months in whom UTI was suspected, usually because no source of fever was apparent (5.9%), and (3) infants with no suspected UTI, most of whom had other illnesses (5.1%). Female and white infants had significantly more UTIs, respectively, than male and black infants. In all, 17% of white female infants with temperature > or = 39 degrees C had UTI, significantly more (p < 0.05) than any other grouping of infants by sex, race, and temperature. Febrile infants with no apparent source of fever were twice as likely to have UTI (7.5%) as those with a possible source of fever such as otitis media (3.5%) (p = 0.02). Only 1 (1.6%) of 62 subjects with an unequivocal source of fever, such as meningitis, had UTI. As indicators of UTI, pyuria and bacteriuria had sensitivities of 54% and 86% and specificities of 96% and 63%, respectively. In infants with fever, clinicians should consider UTI a potential source and consider a urine culture as part of the diagnostic evaluation.

A prospective study of asymptomatic bacteriuria in sexually active young women

BACKGROUND

Asymptomatic bacteriuria is common in young women, but little is known about its pathogenesis, natural history, risk factors, and temporal association with symptomatic urinary tract infection.

METHODS

We prospectively evaluated 796 sexually active, nonpregnant women from 18 through 40 years of age over a period of six months for the occurrence of asymptomatic bacteriuria (defined as at least 10(5) colony-forming units of urinary tract pathogens per milliliter). The women were patients at either a university student health center or a health maintenance organization. Periodic urine cultures were taken, daily diaries were kept, and regularly scheduled interviews were performed. Escherichia coli strains were tested for hemolysin, the papG genotype, and the ribosomal RNA type.

RESULTS

The prevalence of asymptomatic bacteriuria (the proportion of urine cultures with bacteriuria in asymptomatic women) was 5 percent (95 percent confidence interval, 4 percent to 6 percent) among women in the university group and 6 percent (95 percent confidence interval, 5 percent to 8 percent) among women in the health-maintenance-organization group. Persistent asymptomatic bacteriuria with the same E. coli strain was rare. Symptomatic urinary tract infection developed within one week after 8 percent of occasions on which a culture showed asymptomatic bacteriuria, as compared with 1 percent of occasions when asymptomatic bacteriuria was not found (P<0.001). Asymptomatic bacteriuria was associated with the same risk factors as for symptomatic urinary tract infection, particularly the use of a diaphragm plus spermicide and sexual intercourse.

CONCLUSIONS

Asymptomatic bacteriuria in young women is common but rarely persists. It is a strong predictor of subsequent symptomatic urinary tract infection.

Fever, bacteremia, and death as complications of bacteriuria in women with long-term urethral catheters

Numbers of nursing home beds now exceed hospital beds in the United States and are usually occupied by women. Urinary incontinence is very common and may be managed with long-term urethral catheters. Bacteriuria invariably results, yet its clinical consequences are not well known. We studied 47 catheterized and bacteriuric women for almost 25 patient-years. The incidence of febrile episodes of possible urinary origin was 1.1 episodes/100 patient-days. Because these were diagnoses of exclusion, even this low incidence may be an overestimate. Most of these episodes were of less than or equal to 38.3 C (101.0 F), lasted for less than one day, and resolved without antibiotic therapy. Six deaths, half the total from all causes, occurred during these episodes, an incidence 60 times that during afebrile periods. Deaths and bacteremias were significantly associated with episodes of greater than or equal to 38.8 C (102.0 F). In the individual patient, these risks should be weighed against benefits of patient comfort, family satisfaction, and prevention and management of decubitus ulcers.

Asymptomatic bacteriuria: when to screen and when to treat

Asymptomatic bacteriuria is common. Populations with structural or functional abnormalities of the genitourinary tract may have an exceedingly high prevalence of bacteriuria, but even healthy individuals frequently have positive urine cultures. Asymptomatic bacteriuria is seldom associated with adverse outcomes. Pregnant women and individuals who are to undergo traumatic genitourinary interventions are at risk for complications of bacteriuria and benefit from screening and treatment programs. Although screening is recommended for renal transplant recipients, the benefits for these patients are less clear. For other populations, including most bacteriuric individuals, negative outcomes attributable to asymptomatic bacteriuria have not been described. Treatment of asymptomatic bacteriuria in these patients is not beneficial and, in fact, may be associated with harmful outcomes, such as increased short-term frequency of symptomatic infection, adverse drug effects, and reinfection with organisms of increased antimicrobial resistance. Screening for asymptomatic bacteriuria and treatment is recommended for only selected groups where benefit has been shown. Many research questions still need to be addressed. Different populations have unique risk factors, and the benefits and risks of different management approaches for asymptomatic bacteriuria must continue to be addressed systematically in appropriate clinical trials.

Bacteriuria and survival in old age

We studied the effect of asymptomatic bacteriuria on survival in 342 healthy residents of a home for the aged. At entry into the study 76 subjects (22 per cent) had bacteriuria on two consecutive urine cultures. There were no differences in age distribution, blood pressure, hematocrit, smoking habits, cholesterol, or myocardial changes between bacteriuric and nonbacteriuric subjects. Median survival was 53 and 75 months in nonbacteriuric men and women 70 to 79 years old, and 45 months in all nonbacteriuric subjects over 79; median survival of bacteriuric men and women aged 70 to 79 was 33 and 34 months, and that of those older was 31 and 29.5 months; the shorter survival of bacteriuric subjects was significant (P less than 0.003). These differences in mortality among subjects living under identical conditions and with equal prevalence of risk factors indicate that bacteriuria in old age is associated with a reduction in survival of 30 to 50 per cent.

Bacteriuria and mortality in an elderly population

Bacteriuria detected in the screening of adult and elderly populations has been associated with an increased mortality rate, but it is not clear whether the increase is a result of the bacteriuria itself or of differences in age, concomitant disease, or both. We screened a representative sample of the elderly population of Göteborg, Sweden (n = 1966), for bacteriuria. The mean (+/- SD) age at the time of screening was 70 years +/- 2 months. The five-year mortality among women with bacteriuria was 13.4 percent, whereas that among women without bacteriuria was 9.4 percent. The nine-year mortality in the two groups of women was 23.9 and 23.3 percent, respectively (P not significant). When the women with indwelling catheters were excluded from the analysis, the five-year mortality was 9.0 and 9.2 percent, respectively. Men with bacteriuria had an increased frequency of cancer (27.3 vs. 5.8 percent at age 70; P less than 0.002) and a higher five-year mortality than the other men; however, among the men with bacteriuria but not cancer the mortality was not increased. We conclude that fatal diseases associated with bacteriuria may account for the increase in mortality among elderly patients with bacteriuria.

Antimicrobial treatment in diabetic women with asymptomatic bacteriuria

BACKGROUND

Asymptomatic bacteriuria is common among women with diabetes, and the treatment of such infections has been recommended to prevent complications related to symptomatic urinary tract infection.

METHODS

We enrolled women (>16 years of age) with diabetes, bacteriuria (> or =105 colony-forming units of an organism per milliliter in cultures of two consecutive urine specimens), and no urinary symptoms; 50 were randomly assigned to receive placebo and 55 to receive antimicrobial therapy. For the first six weeks, which included the initial course of treatment, the study was placebo-controlled and double-blind. Subsequently, the women were screened for bacteriuria every three months for up to three years; antimicrobial therapy was provided to women in the antimicrobial-therapy group who had asymptomatic bacteriuria.

RESULTS

Four weeks after the end of the initial course of therapy, 78 percent of placebo recipients had bacteriuria, as compared with 20 percent of women who received antimicrobial agents (P<0.001). During a mean follow-up of 27 months, 20 of 50 women in the placebo group (40 percent) and 23 of 55 women in the antimicrobial-therapy group (42 percent) had at least one episode of symptomatic urinary tract infection. The time to a first symptomatic episode was similar in the placebo group and the antimicrobial-therapy group (P=0.67 by the log-rank test), as were the (+/-SD) rates of any symptomatic urinary tract infection (1.10+/-0.17 and 0.93+/-0.14 per 1000 days of follow-up, respectively; relative risk, 1.19; 95 percent confidence interval, 0.28 to 1.81), pyelonephritis (0.28+/-0.08 and 0.13+/-0.05 per 1000 days of follow-up; relative risk, 2.13; 95 percent confidence interval, 0.81 to 5.62), and hospitalization for urinary tract infection (0.10+/-0.36 and 0.06+/-0.22 per 1000 days of follow-up; relative risk, 1.93; 95 percent confidence interval, 0.47 to 7.89). The women in the antimicrobial-therapy group had almost five times as many days of antibiotic use for urinary tract infection as did the women in the placebo group (158.2+/-1.7 vs. 33.7+/-0.91 per 1000 days of follow-up; relative risk, 0.21; 95 percent confidence interval, 0.20 to 0.22).

CONCLUSIONS

Treatment of asymptomatic bacteriuria in women with diabetes does not appear to reduce complications. Diabetes itself should not be an indication for screening for or treatment of asymptomatic bacteriuria.

Bacteriuria and primary biliary cirrhosis

Significant bacteriuria was found in 19% of 87 women with primary biliary cirrhosis, whereas in 89 women with other types of chronic liver disease bacteriuria was present in only 7%. In 74 women with rheumatoid arthritis 8% were bacteriuric. Midstream urine specimens obtained from 144 consecutive women with primary biliary cirrhosis attending hospital over a two year period showed that 50 (35%) developed bacteriuria during 12 months of follow up. Bacteriuria was unrelated to age, raised serum bilirubin, drug therapy or urinary pH but was more common in patients with late stage (fibrotic) disease as judged by histological criteria. Fifty seven per cent of bacteriuric primary biliary cirrhosis patients suffered more than one urinary infection. Fifty nine per cent of the 156 bacteriuric episodes were asymptomatic. The types of organism isolated, the antibiotic sensitivity patterns and cure rate were similar to those reported in bacteriuric women without other underlying disease. The reinfection rate (34%), however, was double that reported for bacteriuric episodes in 'problem' women with recurrent bacteriuria, indicating a special susceptibility to urinary infection. The most common isolates were E coli (70%), which did not show abnormal adhesiveness to uroepithelial or buccal cells of normal women, or to those of primary biliary cirrhosis patients. Patients with primary biliary cirrhosis have not been reported to be more susceptible to infection in general. Bacteriuria, however, was common throughout all clinical stages of primary biliary cirrhosis. Thus there may be a unique association between bacteriuria and primary biliary cirrhosis.

Lack of association between bacteriuria and symptoms in the elderly

In a study of bacteriuria in elderly (mean age 85 years, range 69 to 101), mostly middle- and upper-class Jewish subjects, attempts were made to determine if bacteriuria without dysuria is otherwise asymptomatic. Seventy-two subjects (59 women and 13 men) without dysuria were questioned about other urinary symptoms (incontinence, frequency, urgency, suprapubic pain, flank pain, fever) and symptoms indicating a lack of well-being (anorexia, difficulty in falling asleep, difficulty in staying asleep, fatigue, malaise, weakness) when they were with and without bacteriuria. Twenty-two subjects had bacteriuria that resolved spontaneously; bacteriuria subsequently developed in 24 nonbacteriuric subjects; and 26 subjects had bacteriuria that resolved with antimicrobial therapy. Subjects occasionally reported urinary symptoms (especially incontinence) and commonly reported symptoms indicating a lack of well-being when they were with and/or without bacteriuria. However, no differences in symptoms were found when bacteriuric subjects were compared with themselves when they were nonbacteriuric. Thus, bacteriuria without dysuria in the elderly appears to be asymptomatic.

Maternal and neonatal consequences of treated and untreated asymptomatic bacteriuria in pregnancy: a prospective cohort study with an embedded randomised controlled trial

BACKGROUND

Existing approaches for the screening and treatment of asymptomatic bacteriuria in pregnancy are based on trials that were done more than 30 years ago. In this study, we reassessed the consequences of treated and untreated asymptomatic bacteriuria in pregnancy.

METHODS

In this multicentre prospective cohort study with an embedded randomised controlled trial, we screened women (aged ≥18 years) at eight hospitals and five ultrasound centres in the Netherlands with a singleton pregnancy between 16 and 22 weeks' gestation for asymptomatic bacteriuria. Screening was done with a single dipslide and two culture media. Dipslides were judged positive when the colony concentration was at least 1×10(5) colony-forming units (CFU) per mL of a single microorganism or when two different colony types were present but one had a concentration of at least 1×10(5) CFU per mL. Asymptomatic bacteriuria-positive women were eligible to participate in the randomised controlled trial comparing nitrofurantoin with placebo treatment. In this trial, participants were randomly assigned 1:1 to receive either nitrofurantoin 100 mg or identical placebo tablets, and were instructed to self-administer these tablets twice daily for 5 consecutive days. Randomisation was done by a web-based application with a computer-generated list with random block sizes of two, four, or six participants rendered by an independent data manager. 1 week after the end of treatment, they provided us with a follow-up dipslide. Women, treating physicians, and researchers all remained unaware of the bacteriuria status and treatment allocation. Women who refused to participate in the randomised controlled trial did not receive any antibiotics, but their outcomes were collected for analysis in the cohort study. We compared untreated and placebo-treated asymptomatic bacteriuria-positive women with asymptomatic bacteriuria-negative women and nitrofurantoin-treated asymptomatic bacteriuria-positive women. The primary endpoint was a composite of pyelonephritis with or without preterm birth at less than 34 weeks, analysed by intention to treat at 6 weeks post-partum. This trial is registered with the Dutch Trial Registry, number NTR3068.

FINDINGS

Between Oct 11, 2011, and June 10, 2013, we enrolled 5621 women into our screening cohort, of whom 5132 were eligible for screening. After exclusions for contaminated dipslides and patients lost to follow-up, in our final cohort of 4283 women, 248 were asymptomatic bacteriuria positive, of whom 40 were randomly assigned to nitrofurantoin and 45 to placebo for the randomised controlled trial, whereas the other 163 asymptomatic bacteriuria-positive women were followed without treatment. The proportion of women with pyelonephritis, preterm birth, or both did not differ between untreated or placebo-treated asymptomatic bacteriuria-positive women and asymptomatic bacteriuria-negative women (6 [2·9%] of 208 vs 77 [1·9%] of 4035; adjusted odds ratio [OR] 1·5, 95% CI 0·6-3·5) nor between asymptomatic bacteriuria-positive women treated with nitrofurantoin versus those who were untreated or received placebo (1 [2·5%] of 40 vs 6 [2·9%] of 208; risk difference -0·4, 95% CI -3·6 to 9·4). Untreated or placebo-treated asymptomatic bacteriuria-positive women developed pyelonephritis in five [2·4%] of 208 cases, compared with 24 [0·6%] of 4035 asymptomatic bacteriuria-negative women (adjusted OR 3·9, 95% CI 1·4-11·4).

INTERPRETATION

In women with an uncomplicated singleton pregnancy, asymptomatic bacteriuria is not associated with preterm birth. Asymptomatic bacteriuria showed a significant association with pyelonephritis, but the absolute risk of pyelonephritis in untreated asymptomatic bacteriuria is low. These findings question a routine screen-treat-policy for asymptomatic bacteriuria in pregnancy.

FUNDING

ZonMw (the Netherlands Organisation for Health Research and Development).

Antibiotics for asymptomatic bacteriuria in pregnancy

BACKGROUND

Asymptomatic bacteriuria occurs in 2% to 10% of pregnancies and, if not treated, up to 30% of mothers will develop acute pyelonephritis. Asymptomatic bacteriuria has been associated with low birthweight and preterm delivery.

OBJECTIVES

To assess the effect of antibiotic treatment for asymptomatic bacteriuria on persistent bacteriuria during pregnancy, the development of pyelonephritis and the risk of low birthweight and preterm delivery.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2007).

SELECTION CRITERIA

Randomized trials comparing antibiotic treatment with placebo or no treatment in pregnant women with asymptomatic bacteriuria found on antenatal screening.

DATA COLLECTION AND ANALYSIS

We assessed trial quality.

MAIN RESULTS

Fourteen studies were included. Overall the study quality was poor. Antibiotic treatment compared to placebo or no treatment was effective in clearing asymptomatic bacteriuria (risk ratio (RR) 0.25, 95% confidence interval (CI) 0.14 to 0.48). The incidence of pyelonephritis was reduced (RR 0.23, 95% CI 0.13 to 0.41). Antibiotic treatment was also associated with a reduction in the incidence of low birthweight babies (RR 0.66, 95% CI 0.49 to 0.89) but a difference in preterm delivery was not seen.

AUTHORS' CONCLUSIONS

Antibiotic treatment is effective in reducing the risk of pyelonephritis in pregnancy. A reduction in low birthweight is consistent with current theories about the role of infection in adverse pregnancy outcomes, but this association should be interpreted with caution given the poor quality of the included studies.

The relationship between pyuria and infection in patients with indwelling urinary catheters: a prospective study of 761 patients

BACKGROUND

Pyuria is universally considered as essential for identifying urinary tract infections in noncatheterized patients. The utility of pyuria in the catheterized patient, to identify catheter-associated urinary tract infection (CAUTI), has not been adequately defined.

METHODS

We prospectively studied 761 newly catheterized patients in a university hospital; 82 (10.8%) developed nosocomial CAUTI (> 10(3) colony-forming units per milliliter). While catheterized, each patient was seen daily, a quantitative urine culture was obtained, and the urine white blood cell concentration was measured quantitatively using a hemocytometer.

RESULTS

The mean urine leukocyte count in patients with CAUTI was significantly higher than in patients without infections (71 vs 4 per microliter; P= .006). Pyuria was most strongly associated with CAUTI caused by gram-negative bacilli (white blood cell count, 121 vs 4 per microliter; P = .03); infection with coagulase-negative staphylococci and enterococci (white blood cell count, 39 vs 4 per microliter; P = .25) or yeasts (white blood cell count, 25 vs 4 per microliter; P = .15) produced much less pyuria. Pyuria with a white blood cell count greater than 10 per microliter (>5 per high-power field in a conventional urinalysis) had a specificity of 90% for predicting CAUTI with greater than 10(5) colony-forming units per milliliter but a sensitivity of only 37%.

CONCLUSIONS

In patients with short-term indwelling urinary catheters, pyuria is less strongly correlated with CAUTI than in noncatheterized patients with urinary tract infection. The strongest association is with CAUTI caused by gram-negative bacilli; the association is far weaker for infections caused by gram-positive cocci or yeasts. Most patients with CAUTI are asymptomatic and do not have associated fever. Pyuria should not be used as the sole criterion to obtain a urine culture in a patient with a catheter.

Urinary tract infections during pregnancy

Urinary tract infections are relatively common in pregnancy and may result in significant morbidity for the pregnant woman and fetus. The authors recommend that all pregnant women be screened for the presence of bacteriuria at their first prenatal visit. Failure to treat bacteriuria during pregnancy may result in as many as 25% of women experiencing acute pyelonephritis. Women with acute pyelonephritis may sustain significant complications, such as preterm labor, transient renal failure, ARDS, sepsis and shock, and hematologic abnormalities. Pregnant women with urinary tract infections should be followed up closely after treatment because as many as one third will experience a recurrence.

The detection of pyelonephritic scarring in children by radioisotope imaging

Radioisotope scintigraphy of the kidney and intravenous urography have been compared in 79 children with bacteriologically proven urinary tract infections, followed up over a period of between one and four years. Both techniques were in agreement as to the presence or absence of an abnormality, and the extent of any abnormality present, in 93.5% of the kidneys studied. There was a discrepancy in ten kidneys. Excretion urography has a sensitivity of 0.86 and a specificity of 0.92 in the detection of pyelonephritic scarring in children. Radioisotope scintigraphy has a sensitivity of 0.96 and a specificity of 0.98. It is therefore concluded that radioisotope scintigraphy is the preferred technique.

Urinary tract infections in children

Urinary tract infections (UTIs) in children are among the most common bacterial infections in childhood. They are equally common in boys and girls during the first year of life and become more common in girls after the first year of life. Dividing UTIs into three categories; febrile upper UTI (acute pyelonephritis), lower UTI (cystitis), and asymptomatic bacteriuria, is useful for numerous reasons, mainly because it helps to understand the pathophysiology of the infection. A single episode of febrile UTI is often caused by a virulent Escherichia coli strain, whereas recurrent infections and asymptomatic bacteriuria commonly result from urinary tract malformations or bladder disturbances. Treatment of an upper UTI needs to be broad and last for 10 days, a lower UTI only needs to be treated for 3 days, often with a narrow-spectrum antibiotic, and asymptomatic bacteriuria is best left untreated. Investigations of atypical and recurrent episodes of febrile UTI should focus on urinary tract abnormalities, whereas in cases of cystitis and asymptomatic bacteriuria the focus should be on bladder function.

Cytokine secretion is impaired in women with diabetes mellitus

BACKGROUND

As women with diabetes mellitus (DM) have an increased prevalence of asymptomatic bacteriuria (ASB) and it is known that a correlation exists between the increased prevalence of genitourinary tract infection and impaired cytokine production in women infected with Human Immunodeficiency Virus (HIV), we studied urinary cytokine excretion in diabetic women and compared it with that of nondiabetic controls.

MATERIALS AND METHODS

To evaluate the cytokine secretion capacity of women with DM, both whole blood and isolated monocytes of women with and without DM were stimulated in vitro with lipopolysaccharide (LPS).

RESULTS

Lower urinary interleukin-8 (IL-8) and interleukin-6 (IL-6) concentrations (P = 0.1 and P < 0.001, respectively) were found in diabetic women than in nondiabetic controls. A lower urinary leukocyte cell count correlated with lower urinary IL-8 and IL-6 concentrations (P < 0.05). Lower tumour necrosis factor-alpha (TNF-alpha) and IL-6, but comparable interleukin-10 (IL-10) concentrations were found in whole blood (P < 0.04) and isolated monocytes (P = 0.03) of women with DM type 1 compared to women without DM.

CONCLUSIONS

Diabetic women with ASB have lower urinary IL-6 concentrations than nondiabetic bacteriuric controls. In addition, monocytes of women with DM type 1 secrete lower pro-inflammatory cytokines after stimulation with LPS than monocytes of women without DM. This is not due to an inhibitory effect of the anti-inflammatory cytokine IL-10. This can have important consequences for both host defense, endothelial cell functioning and atherogenesis.

Causes of the excessive rates of perinatal mortality and prematurity in pregnancies complicated by maternal urinary-tract infections

The study was undertaken to determine the causes of the more frequent pre-term deliveries, fetal and neonatal deaths associated with maternal urinary-tract infections during pregnancy. The combined perinatal mortality rate for eight common placental and fetal disorders was 42 per thousand births in the infected vs. 21 per thousand in the noninfected, owing to a greater mortality from noninfectious placental and fetal disorders in the gestations with the urinary-tract infections (P less than 0.001). All the mortality excess took place when the urinary-tract infections occurred within 15 days of delivery. Death rates were highest when the urinary-tract infections coexisted with maternal hypertension and acetonuria.Hydramnios, amniotic-fluid bacterial infections and abruptio placentae were responsible for two thirds of the more frequent preterm deliveries in the pregnancies complicated by urinary-tract infections.

Randomized, double-blind trial of Lithostat (acetohydroxamic acid) in the palliative treatment of infection-induced urinary calculi

In a prospective, double-blind, placebo-controlled study, the efficacy and safety of acetohydroxamic acid (AHA) in preventing urinary calculogenesis was evaluated in 94 patients with chronic urinary infection. Stone growth occurred in 17% of the AHA group and in 46% of the placebo group (p less than 0.005). Completely reversible side effects consisting predominantly of psychoneurologic and musculo-integumentary symptoms were more prevalent in the AHA group (p less than 0.01). Side effects which were judged 'intolerable' were experienced by 10 (22.2%) of patients in the AHA group and 2 (4.1%) in the placebo group. It is concluded that AHA treatment is effective, relatively safe, and clinically useful in preventing infection-induced urinary calculogenesis.

Covert bacteriuria of childhood. A clinical and epidemiological study

A 4-year screening programme for covert bacteriuria in Dundee primary schoolgirl entrants showed a prevalence of 1·6% and an annual incidence of 0·9%. Among 109 children with bacteriuria, 70% had symptoms of lower urinary tract infection, 35% had vesicoureteric reflux, and 23% radiological evidence of pyelonephritis. Both pyuria and a past history of urinary infection were related to radiological evidence of reflux or pyelonephritis. Covert bacteriuria was found more frequently in children from social classes IV and V; and their housing, home circumstances, and home care were worse than a control group, even when allowance was made for their social class differences. The children appeared generally healthy but were smaller than a control group. The data suggest that the great majority of these children are not seriously at risk and that there is at present not sufficient evidence to warrant prescriptive screening.

Effect of glucose and pH on uropathogenic and non-uropathogenic Escherichia coli: studies with urine from diabetic and non-diabetic individuals

It is generally assumed that one of the reasons why diabetics are more susceptible to urinary tract infections than non-diabetics is their 'sweet urine'. However, very little information is available on this subject. Therefore, the growth rates of different Escherichia coli strains were studied in human urine with and without added glucose and with and without a constant pH, and compared with their growth rates in Mueller-Hinton broth (MHB). Eight isolates were used (three from blood cultures from urosepsis patients, two urinary isolates, two faecal isolates and one laboratory strain K12). All isolates grew better in MHB than in urine, but with the exception of the laboratory strain, they had the same growth rate in urine. No significant difference was found between the growth rate in urine from diabetics without glucosuria and that in urine from non-diabetics. The addition of glucose (up to a concentration of 1000 mg/dl) to urine and MHB enhanced the growth rate of all isolates. However, very high concentrations of glucose (up to 10000 mg/dl) in urine and MHB caused a decrease in bacterial growth rate when the urinary pH was not kept constant. The stationary phase was reached later and the final bacterial yield was greater when the urine was made less acidic. As the uropathogenic strains did not grow better in urine than the other isolates, it may be concluded that better growth in urine is not one of the causes of the greater virulence of these strains.

Toll-like receptor 4 promoter polymorphisms: common TLR4 variants may protect against severe urinary tract infection

Background

Polymorphisms affecting Toll-like receptor (TLR) structure appear to be rare, as would be expected due to their essential coordinator role in innate immunity. Here, we assess variation in TLR4 expression, rather than structure, as a mechanism to diversify innate immune responses.

Methodology/Principal Findings

We sequenced the TLR4 promoter (4,3 kb) in Swedish blood donors. Since TLR4 plays a vital role in susceptibility to urinary tract infection (UTI), promoter sequences were obtained from children with mild or severe disease. We performed a case-control study of pediatric patients with asymptomatic bacteriuria (ABU) or those prone to recurrent acute pyelonephritis (APN). Promoter activity of the single SNPs or multiple allelic changes corresponding to the genotype patterns (GPs) was tested. We then conducted a replication study in an independent cohort of adult patients with a history of childhood APN. Last, in vivo effects of the different GPs were examined after therapeutic intravesical inoculation of 19 patients with Escherichia coli 83972. We identified in total eight TLR4 promoter sequence variants in the Swedish control population, forming 19 haplotypes and 29 genotype patterns, some with effects on promoter activity. Compared to symptomatic patients and healthy controls, ABU patients had fewer genotype patterns, and their promoter sequence variants reduced TLR4 expression in response to infection. The ABU associated GPs also reduced innate immune responses in patients who were subjected to therapeutic urinary E. coli tract inoculation.

Conclusions

The results suggest that genetic variation in the TLR4 promoter may be an essential, largely overlooked mechanism to influence TLR4 expression and UTI susceptibility.

Antibiotics for asymptomatic bacteriuria in pregnancy

BACKGROUND

Up to 30% of mothers develop acute pyelonephritis if asymptomatic bacteriuria is untreated. Asymptomatic bacteriuria may have a role in preterm birth, or it may be a marker for low socioeconomic status and thus, low birth weight.

OBJECTIVES

The objective of this review was to assess the effect of antibiotic treatment for asymptomatic bacteriuria on persistent bacteriuria during pregnancy, the risk of preterm delivery and the development of pyelonephritis after delivery.

SEARCH STRATEGY

I searched the Cochrane Pregnancy and Childbirth Group trials register.

SELECTION CRITERIA

Randomised trials comparing antibiotic treatment with placebo or no treatment in pregnant women with asymptomatic bacteriuria found on antenatal screening.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed.

MAIN RESULTS

Thirteen studies were included. Overall the study quality was not strong. Antibiotic treatment compared to placebo or no treatment was effective in clearing asymptomatic bacteriuria (odds ratio 0.07, 95% confidence interval 0.05 to 0.10). The incidence of pyelonephritis was reduced (odds ratio 0.25, 95% confidence interval 0.19 to 0.32). Antibiotic treatment was also associated with a reduction in the incidence of preterm delivery or low birth weight babies (odds ratio 0.60, 95% confidence interval 0.45 to 0.80).

REVIEWER'S CONCLUSIONS

Antibiotic treatment appears to be effective in reducing the risk of pyelonephritis in pregnancy. An apparent reduction in preterm delivery is consistent with current theories about the role of infection in preterm birth, but this association should be interpreted with caution.