Acute Focal Bacterial Nephritis in an Infant Referred with Apnea Caused by Mixed Infection with <i>Enterococcus raffinosus</i> and <i>Escherichia coli</i>

A 38-day-old infant was referred to our hospital for evaluation of apnea, fever, and pyuria. Invasive bacterial infection, including meningitis, was suspected because of the presence of apnea. A contrast-enhanced CT scan revealed acute localized bacterial nephritis, and meningitis was ruled out. Gram-positive cocci and Gram-negative rods, ie, Enterococcus raffinosus and Escherichia coli, were isolated from a urine culture at the referring hospital. This case report describes the youngest case of E. raffinosus infection. Apnea was the main complaint, but the origin of fever was infant acute focal bacterial nephritis (AFBN) with mixed infection. In infants, bacterial infections, especially invasive bacterial infections, can result in poor outcomes and require careful evaluation and treatment. Furthermore, the possibility of AFBN should not be overlooked, because bacteriuria or leukocyturia may be absent and can flare up if antimicrobials are not administered for an adequate duration. Although ampicillin-susceptible E. raffinosus infection in our patient responded well to treatment, there have been reports of vancomycin-resistant enterococci, which highlights the importance of proper use of antimicrobial agents to avoid producing drug-resistant bacteria.