Urinary tract infections in childhood: an update

Cotrimoxazole and neonatal kernicterus: a review

Sulfamethoxazole (SMX) and trimethoprim (TMP) individually and a combination known as cotrimoxazole (SMX-TMP) are widely used for the treatment of protozoan and bacterial infections. SMX-TMP is also one of the widely used antibiotics administered orally in neonates, along with gentamicin injection, for treating pneumonia and sepsis by home-based healthcare providers in Asian countries. Although the use of this drug has successfully reduced neonate mortality, there is a concern for it causing neurotoxicity. Previous clinical studies with sulfisoxazole have demonstrated occurrence of kernicterus in neonates. This sulfonamide is thought to displace bilirubin from its albumin-binding sites in plasma leading to an elevation of plasma bilirubin, which crosses the blood-brain barrier, reaches central neurons to cause kernicterus. We performed an extensive review of clinical and animal studies with cotrimoxazole, which showed no reported incidences of kernicterus with SMX-TMP use in neonates. EndNote, BasicBiosis, Embase, PubMed and Toxline database searches were conducted using specific keywords yielding 74 full-length articles relevant to the review. This review has taken into account various factors, including the disease itself, direct effects of the drug and its metabolism through conjugation and acetylation through a thorough review of the literature to examine the potentials of SMX-TMP to cause kernicterus in neonates. SMX-TMP in oral doses administered to neonates for 7-10 days is unlikely to cause kernicterus. Also, this review recommends warranting the need of future studies using animal models and clinical studies in humans to address SMX-TMP toxicity.

Urinary tract infection in children associated with idiopathic hypercalciuria

OBJECTIVE

The aim of this study was to evaluate the association of symptomatic non-calculous idiopathic hypercalciuria (IH) with urinary tract infection (UTI) in children.

MATERIAL AND METHODS

This was a retrospective case review of children who had urinary calcium excretion greater than 2 mg/kg/day or random urine calcium-creatinine ratio (UCa/UCr) greater than 0.18 mg/mg.

RESULTS

One hundred and twenty-four consecutive children with clinical complaints and elevated urine calcium excretion were reviewed. Fifty children (40%) had UTI of which 39 (78%) had recurrent UTI. There was no difference in age between children with UTI and those without UTI. Twenty-four-hour urine calcium and random UCa/UCr were also not different. Only 4 children (8%) had renal stones whereas hematuria, abdominal pain and urine incontinence were frequent associated findings. Six of the children with recurrent UTI (15%) had an anatomical urinary tract abnormality. Therapy in all children consisted of increased fluid intake and reduction in diet sodium and oxalate; however, 14 of the 39 children with recurrent UTI (36%) required therapy with a thiazide diuretic. Recurrent UTI was abolished in 24 children, one child had a single recurrence and 4 children had no response to treatment.

CONCLUSIONS

We propose that non-calculous IH may be an important contributing factor to recurrent UTI in children.

[Current definition of urinary tract infection in the child]

Urinary tract infections (UTI) encompass a spectrum of clinical and pathological conditions involving various parts of the urinary tract. Differentiating the syndromes associated with UTI has important implications for treatment and prognosis. To effectively communicate information on the subject, terminology should be standardized and precise--a challenge as it is difficult to strictly adapt the terms into French and subsequently apply them to practice.

[Urinary tract infection in the newborn infant]

Urinary tract infection in the first month of life may be revealed by isolated fever, poor weight gain or severe sepsis. It is more frequent in male infants. Escherichia coli is the most common infecting agent. A urinary tract malformation is found in approximately 30% of the cases. In most cases intravenous treatment with an association of cephalosporin and aminoside is efficient. However, because of the possible involvement of an enterococcus, amoxicillin must be added until the result of the urine culture is available. Prophylaxis with oral administration of antibiotics is recommended in case of urinary tract malformation.

Scintigraphic evaluation of pediatric urinary tract infection

Scintigraphic evaluation of urinary tract infection, pyelonephritis, and renal scarring represents a significant portion of a clinical pediatric nuclear medicine practice. Renal scarring from recurring infection remains an important cause of end-stage renal disease and hypertension in the pediatric population. However, the clinical presentation in infants and young children is often elusive, and clinical diagnosis of upper tract involvement is frequently unreliable. As a result, diagnostic imaging has a critical role to play in the localization of infection to the lower or upper urinary tract. Radionuclide cystography and renal cortical imaging have become mainstays of this evaluation. Direct radionuclide cystography is the preferred cystographic screening technique, because it has lower radiation exposure and greater sensitivity for the detection of vesicoureteral reflux than either indirect radionuclide cystography or fluoroscopic contrast cystography. Renal cortical scintigraphy has become the standard for the detection of pyelonephritis and renal scarring. Correlation with histopathology has demonstrated a high degree of diagnostic accuracy. Acute pyelonephritis has been shown to be the necessary etiologic factor for the development of subsequent renal scarring, and the mechanism of renal injury in pyelonephritis has been extensively studied in experimental models. The ability of prompt and appropriate antibiotic therapy to dramatically reduce the incidence of subsequent scarring also has been conclusively demonstrated both clinically and in the experimental model. Vesicoureteral reflux was once thought to be a necessary prerequisite for the development of renal scarring. Although it is clear that the intrarenal reflux of infected urine will create pyelonephritis in the experimental model, the high incidence of pyelonephritis and subsequent scarring in the absence of demonstrable vesicoureteral reflux leaves the role of reflux in question. Although the role of vesicoureteral reflux is incompletely understood, its detection nevertheless remains a standard part of the patient's evaluation.

Management of urinary tract infections in children

Urinary tract infection is common in children. The presentation varies with age. Younger children exhibit protean signs. Diagnosis is dependent on the demonstration of significant bacteriuria in a properly collected and handled urine sample. The approach to treatment depends on the degree of illness at presentation, the presence of structural urinary tract abnormalities, and the age of the patient. Pathophysiology of urinary tract infection is dependent on interactive factors of the host and of the invading microorganism. Urinary tract abnormalities have significant impact on the management of children with urinary tract infections, both medically and surgically. Of particular importance is the observation that renal damage usually occurs within the first 5 years of life, and treatment delay in some young patients may have significant consequences. The overall prognosis in children with urinary tract infection is favorable.

Epidemiology and natural history of urinary tract infections in children

Recent retrospective surveys have supported previous investigations in demonstrating the incidence of UTI during infancy; 0.3% to 1.2% of infants develop symptomatic UTI during the first year of life. Boys are more commonly infected during the first 3 months of life. After the first year, symptomatic UTI is much more frequent among girls. Similarly, asymptomatic bacteriuria is more frequently detected in boys than in girls during the first 12 months of life. Thereafter, the incidence decreases markedly in boys but increases in girls. Recent investigations indicate that lack of circumcision is a risk factor for UTI among male infants. Recurrent UTI is common and frequently asymptomatic. The most important microbiologic factor that is associated with E. coli causing acute pyelonephritis is adherence mediated by P fimbriae. Other factors, such as capsule, lipopolysaccharide, aerobactin production, and serum resistance, also determine the invasiveness of E. coli. Vesicoureteral reflux appears to be an important host factor predisposing to UTI. Microbiologic and host factors that are determinants of renal scarring are under investigation.

Microbiology of airway disease in patients with cystic fibrosis

Individuals with cystic fibrosis have abbreviated life spans primarily due to chronic airway infection. A limited number of types of organisms are responsible for these infections, with Staphylococcus aureus and Pseudomonas aeruginosa being of primary importance. In the pre-antibiotic era, greater than 90% of deaths due to infection were caused by S. aureus and death usually occurred in the first 2 years of life. With the advent of effective antistaphylococcal therapy, life spans increased and P. aeruginosa became the pathogen of primary importance. P. aeruginosa isolates recovered from patients with cystic fibrosis have a unique phenotypic characteristic referred to as "mucoid." The mucoid phenotype is due to the production of a mucoid exopolysaccharide. A mucoid exopolysaccharide is believed to play a central role in the establishment of chronic pseudomonal lung infection in these patients. A third organism, Pseudomonas cepacia, has recently been detected in the airways of older patients with cystic fibrosis and is associated with increased mortality. The virulence of P. cepacia is not understood, but the organism is extremely refractory to antimicrobial therapy. Other bacteria, including Haemophilus influenzae and members of the family Enterobacteriaceae, appear to play a secondary role in airway infection. Aspergillus fumigatus is the most important fungal agent causing allergic bronchopulmonary disease. The role of viruses has only recently been examined. At least in some patients with cystic fibrosis, respiratory syncytial virus may be important in predisposing to subsequent bacterial infections.

Home collection of urine specimens--boric acid bottles or Dipslides?

Sterile mid stream specimens of urine (MSSU) were obtained from 84 children in a hospital outpatient department. All 84 children collected urine at home by one of two Dipslide methods and by collection into boric acid within 24 hours of the hospital collected MSSU. The samples collected at home were posted to the hospital. Thirty six of the Dipslides (43%) and nine of the boric acid samples (10%) were not sterile but none had a pure growth of a single organism of greater than 10(5) organisms/ml. In addition, 17 of the Dipslides (20%) were returned with one or both media detached and therefore could not be relied upon to exclude urinary tract infection. In a second part to the study, 95 urines which showed a significant growth in primary culture were also cultured after storage in boric acid. Inhibition was noted in nine samples after storage in boric acid, seven of which were in underfilled bottles. Transport of specimens in boric acid produced less contamination than Dipslides but may inhibit growth in a small number of specimens. Technical failures with Dipslides were disappointingly high.

Single dose trimethoprim for urinary tract infection

A randomised clinical trial of single dose trimethoprim against a seven day course of co-trimoxazole (trimethoprim/sulphamethoxazole) for the treatment of uncomplicated urinary tract infection was carried out in 106 children aged between 2 and 16 years. Of the 50 children with confirmed urinary tract infections who were followed up 48 hours after treatment with a single dose of trimethoprim all were free of infection, whereas two of the 56 who received the course of co-trimoxazole (4%) had persisting infections. At follow up after 10 days, however, significantly more of the group treated with trimethoprim had evidence of recurrent urinary tract infection compared with those who had received co-trimoxazole (10 of 44, 23%, compared with one of 46, 2%). Of the recurrences in the trimethoprim group, six were asymptomatic. We conclude that single dose trimethoprim is effective in clearing the urine of bacteria, but the risk of asymptomatic bacteriuria soon after treatment is high.

Five-year survey of changing patterns of susceptibility of bacterial uropathogens to trimethoprim-sulfamethoxazole and other antimicrobial agents

We analyzed the antibiotic susceptibility of 5,348 urinary isolates of Escherichia coli, "Klebsiella aerogenes," and Proteus mirabilis grown in three laboratories from 1980 to 1985. A continuous rise in resistance to trimethoprim-sulfamethoxazole was observed; 63% of the strains from inpatients in 1984 and 51% of those from outpatients in 1985 were resistant to this drug. Isolates from outpatients in 1985 were mostly susceptible to nitrofurantoin (mean susceptibility, 92%) and to oral cephalosporins (mean susceptibility, 84%). As for isolates from inpatients, none of the antimicrobial agents now used was satisfactory for initial chemotherapy, indicating a need for new antibacterial strategies.