Urinary Tract Infection in Children

CHAPTER 13. Urinary Tract Infection in Children. Andrew L. Freedman, MD. Director of Pediatric Urology. Minimally Invasive Urology Institute …

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Urinary Tract Infection in Children – Chapter 13
Urinary Tract Infection in Children
Andrew L. Freedman, MD
Director of Pediatric Urology Minimally Invasive Urology Institute Cedars-Sinai Medical Center Los Angeles, California

Urinary Tract Infection in Children
Andrew L. Freedman, MD

INTRODUCTION Urinary tract infection (UTI) affects 2.6% to 3.4% of children in the United States annually. Throughout childhood, the risk of UTI is 2% for boys and 8% for girls. UTIs are primarily managed in physicians\’ offices, where they account for more than 1 million visits (0.7% of all pediatric office visits) per year. The emergency room is also an important site of care, accounting for 5% to 14% of physician encounters for pediatric UTI. Inpatient hospitalization is required in 2% to 3% of cases, with UTI accounting for more than 36,000 admissions in 2000. More care is rendered to girls than to boys, at a ratio of 3-4 to 1. Hospitalization is more frequent for infants, but it is more expensive for adolescents. Overall costs for inpatient hospital care increased during the 1990s despite shorter lengths of stay. The cost of hospitalization for UTI amounts to more than $180 million annually. However, the true financial burden is probably much higher because it includes costs for outpatient services, imaging, other diagnostic evaluations, long-term complications, and management of associated conditions that increase the frequency and morbidity of UTI. The economic impact on the family due to parental work loss is largely unknown. Efforts to lessen the economic burden on patients, payers, and society include decreasing the length and frequency of inpatient hospitalizations, streamlining the post-UTI imaging evaluation, developing new antimicrobials to fight resistant organisms, and generating easy-to-implement nonantimicrobial strategies.

DEFINITION AND DIAGNOSIS Normally, the urinary tract proximal to the distal urethra is sterile, but it is constantly challenged by infectious pathogens fighting to gain access. A UTI, strictly speaking, occurs when an infectious agent is present within this sterile system; however, a more appropriate clinical definition is that UTI occurs when the infectious agent is not only present, but is also causing illness. This distinction underscores the inherent clinical difficulty of managing patients with UTI. In practice, a diagnosis of UTI is presumed when irritative urinary tract symptoms occur simultaneously with a positive test for infectious agents, such as bacteria, fungi, viruses, or parasites, in the urinary tract. Because other factors can cause similar symptoms, the presence of symptoms in the absence of a positive culture has historically been considered inadequate for diagnosis. Likewise, the presence of leukocytes in the urine is not proof of infection. Asymptomatic bacteriuria may represent colonization or contamination and should be differentiated from UTI. Thus, for clinical purposes, the definition of a UTI requires a combination of symptoms and laboratory findings. Both the infectious agent and the anatomic location typically define the UTI. The urinary tract is commonly divided into the upper tract (kidneys and ureters) and the lower tract (bladder and urethra). In the male, infections such as prostatitis, epididymitis, and orchitis are frequently included as UTIs but are more accurately considered genital infections; they have a separate epidemiology and natural history.

Urologic Diseases in America

Table 1. ICD-9 codes used in the diagnosis and management of pediatric urinary tract infection Individuals under 18 with any one of the following ICD-9 codes: Cystitis 112.2 120.9 595.9 595.1 595.0 595.3 595.89 595.2 Candidiasis of other urogenital sites Schistosomiasis, unspecified Cystitis, unspecified Chronic interstitial cystitis Acute cystitis Trigonitis Other specified types of cystitis Other chronic cystitis

Pyelonephritis 590.0 590.00 590.01 590.1 590.10 590.11 590.2 590.3 590.8 590.9 593.89 Orchitis 016.5 072.0 603.1 604.0 604.9 604.90 604.99 608.0 608.4 Other 597.89 599.0 607.1 607.2 646.5 Other urethritis Urinary tract infection, site not specified Balanoposthitis Other inflammatory disorders of penis Asymptomatic bacteriuria in pregnancy Tuberculosis of other male genital organs Mumps orchitis Infected hydrocele Orchitis epididymitis and epididymo-orchitis with abscess Other orchitis, epididymitis, and epididymo-orchitis, without mention of abscess Orchitis and epididymitis, unspecified Other orchitis epididymitis and epididymo-orchitis without abscess Seminal vesiculitis Other inflammatory disorders of male genital organs Chronic pyelonephritis Chronic pyelonephritis without lesion of renal medullary necrosis Chronic pyelonephritis with lesion of renal medullary necrosis Acute pyelonephritis Acute pyelonephritis without lesion of renal medullary necrosis Acute pyelonephritis with lesion of renal medullary necrosis Renal and perinephric abscess Pyeloureteritis cystica Other pyelonephritis or pyonephrosis, not specified as acute or chronic Infection of kidney, unspecified Other specified disorders of kidney and ureter

Urinary Tract Infection in Children

In this chapter, genital infections are excluded from the definition of UTI, and non-sexually transmitted orchitis is discussed separately. UTIs are also categorized as complicated or uncomplicated. Complicated UTIs are infections in which there is a comorbidity that predisposes a child either to infection or to greater morbidity due to the infection. Comorbidities include the presence of stones, neurological impairment affecting urinary tract functioning, and anatomic abnormalities such as obstruction, reflux, or enterovesical fistula. UTI is a frequent complication of medical care, especially hospitalization. Unfortunately, the datasets analyzed for this chapter preclude distinguishing nosocomial from community-acquired infections. In this compendium, children are defined as persons less than 18 years of age. Where possible, they are further subdivided into infants (under 3 years of age), older children (3 to 10), and adolescents (11 to 17). Most of the datasets analyzed for this chapter do not distinguish the site of the UTI, with the notable exception of data from the Healthcare Cost and Utilization Project (HCUP) and MarketScan, in which pyelonephritis and orchitis, respectively, are distinguished from UTIs in other sites. The method by which the site of UTI is determined in these datasets is based on diagnostic coding and likely varies across the population. The vast majority of UTIs are caused by bacterial agents, the most important of which are the Enterobacteriaciae, a family of gram-negative bacilli. Escherichia coli accounts for more than 80% of acute UTIs in children. The rest of the cases are distributed primarily among Proteus mirabilis, Klebsiella pneumonia, and Pseudomonsa aeruginosa. Less common infectious agents include gram-positive cocci, such as Enterococcus and Staphylococcus. Fungal infections, particularly Candida, are usually seen in nosocomial infections, complicated UTIs, or catheter-associated UTIs. Viral infections are under-recognized because of difficulties with culture and identification, but they have clearly been associated with infectious bladder symptoms. Cytomegalovirus is frequently seen in immunocompromised patients, particularly following organ transplantation. Analyses for this chapter are based on the ICD-9 codes defining UTI listed in Table 1.

The clinical diagnosis of UTI is usually based on a combination of symptoms, physical and radiographic findings, and laboratory results. Diagnostic methods vary markedly and depend on presentation, clinical suspicion, medical history, and local practice patterns. Children pose a unique challenge in the diagnosis of UTI, because they often are unable to provide an accurate history or description of symptoms. Obtaining adequate specimens may also be difficult, and clinical signs such as fever and leukocytosis may be unreliable in the very young. A lower tract infection is typically suspected in the presence of dysuria, urgency, frequency, and, less commonly, suprapubic pain. Upper tract involvement is typically heralded by fever, flank pain, nausea, vomiting, and lethargy. In the young child, there can be significant overlap in the clinical presentations of upper and lower tract infections. Symptoms may not be verbalized, and the diaper may conceal the voiding pattern. Fever is frequently the presenting sign, although lethargy may be the sole indicator of significant infection in infants. Parents\’ perception of an odor is an unreliable sign of infection (1). Hence, the clinician must have a high index of suspicion to make an accurate diagnosis of UTI. Diagnosis is further hindered by the difficulty of obtaining adequate samples for laboratory testing. Urinalysis, the standard initial screening test for UTI, ideally requires a midstream, clean catch of urine, but this may be impossible in the very young. Alternatively, urine can be obtained by sterile catheterization or suprapubic needle aspiration. However, both of these techniques are invasive and frequently met with parental disapproval. Urine may be obtained by the adherence of a sterile collection bag to the perineum, but this method has a high rate of contamination, limiting its reliability. Once obtained, urine is examined with a reagent dipstick for the presence of nitrates and leukocyte esterase. A finding that the urine is crystal clear to visual inspection has a 97% negative predictive value for UTI (2). The urine can also be microscopically examined after gramstain, as well as cultured for the presence of bacteria or fungi. Other adjunctive laboratory tests include serum white blood cell count and C-reactive protein level (3). Imaging studies can assist in diagnosis, but they play a more prominent role in elucidating underlying

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