Persistent bacteremia caused by Ralstonia pickettii and Microbacterium: a case report

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Clinical Bacteriology

Background:

• Ralstonia pickettii, a Gram-negative bacillus, rarely causes human infections but can lead to bacteremia.
• Microbacterium species, Gram-positive coryneforms, are often contaminants in blood cultures, particularly with prolonged time to positivity (>48h).
• Both R. pickettii and Microbacterium are emerging opportunistic pathogens capable of causing severe, life-threatening infections.

Observation:

• A patient presented with bacteremia caused by concurrent infection with R. pickettii and Microbacterium.
• The patient experienced septic shock, a critical condition requiring immediate medical intervention.

Findings:

• The two rare pathogens exhibited opposing drug sensitivity results to imipenem.
• Rapid antibiotic susceptibility testing revealed differential resistance and susceptibility patterns.

Implications:

• This case underscores the importance of prompt antimicrobial susceptibility testing for polymicrobial infections involving rare pathogens.
• Effective antibiotic management, guided by susceptibility results, is paramount for successful treatment outcomes in severe infections.
• Clinicians should consider these bacteria as potential pathogens in severe infections, even if they are typically considered contaminants or low-virulence organisms.