Urinary tract infection with an Enterococcus faecalis isolate that requires vancomycin for growth

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Enterococcus faecalis is a common cause of urinary tract infections.
• Vancomycin is a critical antibiotic for treating infections caused by Gram-positive bacteria, including enterococci.
• Antimicrobial resistance is a growing global health concern.

Observation:

• A unique E. faecalis strain (TJ310) was repeatedly isolated from a patient undergoing long-term vancomycin therapy.
• This strain exhibited an unusual growth requirement, necessitating the presence of vancomycin for cultivation.
• The isolate was found to be vancomycin-dependent, a phenomenon not previously reported in clinical bacterial isolates.

Findings:

• Molecular analysis indicated that strain TJ310 is closely related to vancomycin-resistant, non-dependent E. faecalis strains from the same patient.
• The vanB genotype was identified, suggesting a mechanism for vancomycin resistance.
• The findings suggest that vancomycin dependence evolved in vivo due to continuous exposure to high vancomycin concentrations.

Implications:

• This case represents the first documented instance of a clinical bacterial isolate requiring an antimicrobial agent for growth.
• Understanding the mechanisms of vancomycin dependence can inform strategies for managing complex enterococcal infections.
• The study highlights the adaptability of bacteria and the potential for novel resistance and dependence mechanisms to emerge under selective pressure.