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

## TL;DR

A rare case of Janibacter melonis bacteremia in a lymphoma patient after stem cell mobilization is reported, emphasizing the need for prompt diagnosis and targeted treatment.

## Contribution

This report adds a rare clinical case of Janibacter melonis infection in a hematologic malignancy patient, with detailed diagnostic and treatment insights.

## Key findings

- Janibacter melonis bacteremia occurred in a 37-year-old immunocompromised lymphoma patient after stem cell mobilization.
- Antimicrobial susceptibility testing revealed variable responses, with cefoperazone–sulbactam successfully treating the infection.
- Prompt microbiological and molecular diagnosis led to resolution of symptoms and normalization of inflammatory markers.

## Abstract

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.

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.

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.