Janibacter melonis bacteremia following autologous stem cell mobilization in lymphoma: a case report and literature review.

INTRODUCTION

Infection is a major cause of morbidity and mortality in patients with hematologic malignancies. Janibacter melonis is a rare opportunistic pathogen capable of causing bacteremia even in healthy individuals, yet reports in hematologic malignancy are limited. This case represents one of the few documented infections in this context, with details on diagnostic confirmation, antimicrobial susceptibility, and treatment outcomes.

CASE PRESENTATION: A 37-year-old female with refractory diffuse large B-cell lymphoma developed Janibacter melonis bacteremia following autologous stem cell mobilization. The patient was immunocompromised as a result of prior therapy with a CD20 monoclonal antibody and intensive chemotherapy. She presented with fever and elevated inflammatory markers after consuming possibly spoiled kiwi fruit. Blood cultures identified Janibacter melonis, confirmed by 16 S ribosomal RNA gene sequencing. Antimicrobial susceptibility testing showed relatively weak activity of penicillins, cephalosporins, erythromycin, and clindamycin against the Janibacter melonis strain, whereas fluoroquinolones, aminoglycosides, tetracycline, glycopeptides, carbapenems, sulfonamides, rifampin, linezolid, and daptomycin had lower MICs; nitrofurantoin was inactive. The patient was treated successfully with cefoperazone-sulbactam, resulting in resolution of fever and normalization of inflammatory markers.

CONCLUSIONS

This case highlights the importance of considering rare infections in immunocompromised patients, especially those with hematologic malignancies. Prompt microbiological and molecular diagnosis, combined with targeted therapy, is essential for good outcomes. This report also provides useful insights for managing Janibacter melonis infections.