Mechanisms of fosfomycin resistance in carbapenem-resistant Enterobacter sp

Area of Science:

• Microbiology
• Antimicrobial Resistance
• Clinical Infectious Diseases

Background:

• Carbapenemase-producing Enterobacteriaceae (CPE) are a significant global health threat.
• Enterobacter species are common causes of hospital-acquired infections.
• Fosfomycin is a valuable antibiotic for treating infections caused by multidrug-resistant Gram-negative bacteria.

Purpose of the Study:

• To investigate fosfomycin susceptibility among clinical isolates of bla_KPC-positive Enterobacter species.
• To identify the prevalence of specific fosfomycin resistance genes (fosA, FosA3, FosC2) in these strains.
• To determine the correlation between fosA gene presence and fosfomycin susceptibility.

Main Methods:

• Phenotypic susceptibility testing to fosfomycin was performed on 19 clinical isolates of bla_KPC-positive Enterobacter species.
• Molecular methods (PCR) were used to detect the presence of fosfomycin resistance genes: fosA, FosA3, and FosC2.
• Statistical analysis was conducted to assess the correlation between genotype (fosA presence) and phenotype (fosfomycin susceptibility).

Main Results:

• Out of 19 bla_KPC-positive Enterobacter strains, 14 (74%) exhibited susceptibility to fosfomycin.
• The fosA gene was detected in 8 strains (42%), while FosA3 and FosC2 genes were not found in any of the tested isolates.
• No significant correlation was observed between the presence of the fosA gene and fosfomycin susceptibility.

Conclusions:

• A high proportion of clinical bla_KPC-positive Enterobacter strains remain susceptible to fosfomycin, suggesting its potential utility in treating infections caused by these pathogens.
• The fosA gene, a common mechanism of fosfomycin resistance, was prevalent but did not reliably predict susceptibility in this cohort.
• Further research is warranted to elucidate other resistance mechanisms and optimize the use of fosfomycin against KPC-producing Enterobacter species.