P2.L226: Haemophilus parainfluenzae urinary tract infection and bacteremia in 38-day-old male with structural ureteral abnormality

Introduction: Haemophilus parainfluenzae is a gram-negative coccobacillus found commensally in the upper respiratory, gastrointestinal, and anogenital tracts. Rarely, it is implicated in pediatric urinary tract infections (UTIs) with prevalence estimated at 0.02%. Current UTI diagnostic recommendations for catheter collected urine culture in children is 50,000 colony forming units (CFUs), but recent literature has suggested broadening this cutoff to 10,000 CFUs for ages 1-36 months. Current guidelines advise renal bladder ultrasound (RBUS) to evaluate for urinary tract anomalies.

Case Description: A term 38-day-old male presented with 1 day of fever and fussiness. Blood culture and urine culture via straight catheterization were obtained. Urinalysis demonstrated proteinuria, pyuria, nitrites, moderate leukocyte esterase, and 3+ bacteria. Additional labs showed leukocytosis and elevated procalcitonin and CRP. Cerebrospinal fluid studies were normal. The patient was admitted and started on ceftriaxone with a working diagnosis of urosepsis. Urine culture grew 10-14,000 CFUs H. parainfluenzae and blood culture grew H. parainfluenzae. Following sensitivity results, the patient transitioned to ampicillin for 7 days. Renal ultrasound demonstrated duplex left kidney with mild upper pole hydronephrosis, moderate lower pole hydronephrosis, and mild bladder wall thickening. The patient was discharged with 7 days of high dose amoxicillin followed by low dose prophylactic amoxicillin.

At one-month urology follow-up, voiding cystourethrogram showed left-sided grade 4 vesicoureteral reflux into both the upper and lower poles and bifid left collecting system. Urology recommended continued amoxicillin prophylaxis and a renal flow scan due to the significant anatomical abnormality. At 7 months, a nuclear medicine renal flow scan showed a dilated, non-obstructed left kidney with good drainage of both poles, equal function of the right and left kidneys, good function in both poles of the left kidney, and no evidence of ureteropelvic junction obstruction.

Discussion: H. parainfluenzae is a rare uropathogen and cause of neonatal sepsis. This patient’s urine culture grew 10-14,000 CFUs which is not typically considered diagnostic for UTI on catheterized specimens. However, given the patient’s otherwise unexplained fever and concurrent bacteremia, this culture result is highly suggestive of UTI. This is supported by a recent study supporting a cutoff of 10,000 CFUs for this age. When H. influenza and H. parainfluenza UTI have been reported in pediatric studies, most have been associated with a renal structural abnormality. One study looked at 36 children with either of these infections and found only one patient (2.7%) with normal renal anatomy, 7 (19.4%) with duplex kidneys, 12 (33.3%) with vesicoureteral reflux, and 4 (11.1%) with both duplex kidney and reflux as in our patient.

Conclusion: In neonatal sepsis patients with suspected UTI caused by H. parainfluenzae or other atypical uropathogens, prompt evaluation for renal structural abnormalities is recommended. In febrile infants, liberalized UTI diagnostic criteria to 10,000 CFUs should be considered.