Stenotrophomonas maltophilia External Ventricular Drain Infections: A Case Series.

Abstract

To the Editors: Stenotrophomonas maltophilia is a Gram-negative rod that causes nosocomial infections. Stenotrophomonas is known for biofilm formation, which supports persistent colonization of plastic medical devices.1,2 This organism possesses intrinsic resistance to multiple classes of antibiotics, including many β-lactams. It is therefore frequently not covered by empiric treatment regimens.1,2 We present 3 cases of patients (Table 1) treated at our pediatric hospital who developed Stenotrophomonas external ventricular drain (EVD) infection to highlight difficulties associated with recognition and treatment of this organism. TABLE 1. - Patient Characteristics Case 1 2 3 Gender Female Female Male Age (yr) 13 24 12 Past medical history None Medulloblastoma, ovarian sclerosing stromal tumor Global developmental delay, hydrocephalus requiring VP shunt, seizures, cortical blindness, obstructive sleep apnea, G6PD deficiency CSF results Gram stain No cells, no organisms seen Rare mononuclear cells, rare Gram-negative rods Moderate polys, moderate cells question of type, no organisms seen Protein (mg/dL) 4.2 42.8 191.2 Glucose (mg/dL) 78 75 37 WBC (per mm3) 2 7 35 RBC (per mm3) 64 406 1750 Initial culture Stenotrophomonas maltophilia susceptible to TMP-SMX, ceftazidime, and minocycline S. maltophilia susceptible to TMP-SMX, minocycline, and levofloxacin; resistant to ceftazidime S. maltophilia susceptible to minocycline and levofloxacin; resistant to ceftazidime (TMP-SMX susceptibility testing not requested given his known G6PD deficiency) Days to CSF clearance 12 (on lumbar puncture 1 wk after EVD removal) Not documented (follow-up CSF sampling recommended but performed due to improved clinical status) 1 d Ultimate treatment regimen 21 d TMP-SMX 21 d TMP-SMX 16 d levofloxacin and 12 d minocycline Long-term outcome Transferred to a rehabilitation center for further care, and when she returned to our hospital for routine follow-up a year later, she had returned to her neurologic baseline No recrudescence of Stenotrophomonas and no neurologic deficits attributed to this infection at 2-yr follow-up Following completion of therapy, VP shunt was reinternalized, and the patient had no recrudescent Stenotrophomonas infection in the multiple years since G6PD indicates glucose-6-phosphate dehydrogenase; RBCs, red blood cells; VP, ventriculoperitoneal; WBCs, white blood cells.Note: Levofloxacin use in this setting not approved by the U.S. Food and Drug Administration. CASE 1 A previously healthy 13-year-old required emergent EVD placement after arteriovenous malformation rupture. Fourteen days later, cerebrospinal fluid (CSF) cultures were sent due to fever, and intravenous (IV) vancomycin and cefepime were empirically started. CSF culture grew S. maltophilia. Following identification, antibiotics were transitioned to IV trimethoprim-sulfamethoxazole (TMP-SMX) and ceftazidime; EVD removal was not immediately possible due to continued intracranial pressure elevation. Serial CSF cultures from the EVD persistently grew S. maltophilia until its successful removal 1 week after the initial positive culture. Lumbar puncture performed 1 week after EVD removal yielded negative cultures; she completed a total 21-day course of IV TMP-SMX from first negative culture. CASE 2 A 24-year-old with distant history of medulloblastoma required emergent EVD placement following biopsy of a new skull base osteosarcoma. She was started on chemotherapy with doxorubicin and ifosfamide and developed a fever 5 days after EVD placement; at that point, CSF cultures were negative and nonmeningitically dosed ceftriaxone was started. This was broadened to cefepime the next day when she became neutropenic. Two days later, the height of her fever increased. Antimicrobials were broadened to IV vancomycin and meropenem, then IV ciprofloxacin and TMP-SMX were added given concern for a meropenem-resistant organism. CSF cultures grew S. maltophilia, and EVD was promptly removed. Antibacterials were ultimately narrowed to IV TMP-SMX to complete a total 21-day course. CASE 3 A 12-year-old boy with complex history presented with ventriculoperitoneal shunt malfunction requiring removal and EVD placement. During the prolonged hospitalization, he required multiple EVD replacements. Following a failed removal and emergent replacement, he developed a fever. He was empirically started on meningitically dosed IV vancomycin and ceftriaxone. CSF cultures grew S. maltophilia; IV levofloxacin was added, and he underwent another EVD replacement. IV minocycline was added 4 days later given concerns that resistance could develop on monotherapy. While all 3 patients had good clinical outcomes, these cases present learning opportunities. In all patients, Stenotrophomonas was not initially considered on the differential. The Infectious Diseases Society of America Clinical Practice Guidelines for Healthcare-Associated Ventriculitis and Meningitis do not include Stenotrophomonas coverage in recommended empiric therapy; rather, they appropriately suggest an anti-Pseudomonal β-lactam and vancomycin.3 However, it is important consider empiric therapy for this organism in the appropriate clinical setting. As with any biofilm-forming organism, removal of indwelling foreign material is an essential part of management.3 By maintaining a high index of suspicion and pursing appropriate treatment when necessary, pediatric infectious disease providers can play an important role in optimizing outcomes following Stenotrophomonas infections.