Chapter 101: Neonatal Urinary Tract Infections

INTRODUCTION

Urinary tract infections (UTI) in the neonate pose a number of difficulties for the clinician. Symptoms are vague and overlap with a variety of other conditions. Accurate diagnosis requires testing of urine, which necessitates invasive techniques in the newborn child. The development of a UTI may be associated with the presence of other factors that increase the likelihood of pyelonephritis and subsequent renal scarring. In addition, significant ambiguity exists within the medical community about when further testing is necessary, which tests to obtain, and the appropriate timing of such testing. With these issues in mind, we address the basic workup and treatment of UTI in the neonate and briefly discuss some current controversies.

DIAGNOSIS

Urinary tract infection occurs in 0.1%–0.4% of infant girls, 0.702% of uncircumcised infant boys, and 0.188% of circumcised infant boys.¹ UTI is more common in premature (2.9%) and very low birth weight (4%–25%) infants in comparison to full-term infants (0.7%).² One of the most difficult aspects of UTI in neonates is the lack of any visible signs early in the process. Although adults and older children may experience symptoms such as frequency, urgency, and dysuria at the beginning of a UTI, neonates typically present with a fever or general irritability. The history may include malodorous urine or general fussiness or may consist only of fever. The presence of a fever without an identified focus in a neonate prompts workup, including a full physical examination and obtaining samples of urine, blood, and cerebrospinal fluid for analysis and culture.³ Admission to the hospital and initiation of intravenous antibiotics are routine. As in older children, bacteria of enteric origin cause most UTIs, with Escherichia coli the most common.⁴ Table 101-1 lists some of the most common bacteria causing UTIs in children.

Physical examination in the neonate with a UTI is unlikely to provide any additional information, although the external genitalia should certainly be assessed. The presence of an intact foreskin and degree of physiologic phimosis should be noted in boys, as well as the presence of labial adhesions in girls. These anatomic considerations may complicate the accuracy of urine samples, as well as be potential areas of intervention for prevention of future infections. In addition, evaluation of the lower spine for a sacral dimple should be performed, with ultrasonography of the spine if a deep lesion is identified.

Accurate sampling of urine in neonates requires a sample to be obtained prior to antibiotic administration using either suprapubic aspiration (SPA) or catheterization of the urethra. SPA presents ...