Characterization of Salmonella enterica isolates causing bacteremia in Lima, Peru, using multiple typing methods

Area of Science:

• Microbiology
• Infectious Diseases
• Molecular Epidemiology

Background:

• Salmonella enterica is a significant cause of bloodstream infections globally.
• Characterizing bacterial isolates is crucial for understanding transmission and guiding treatment.
• Molecular typing methods offer high discriminatory power for bacterial strain identification.

Purpose of the Study:

• To molecularly characterize Salmonella enterica blood isolates from Lima, Peru.
• To compare the effectiveness of various molecular typing tools.
• To assess antimicrobial resistance and virulence factors in the isolates.

Main Methods:

• Multiplex PCR serotyping
• Multilocus Sequence Typing (MLST) at two and seven loci
• IS200 amplification
• Random Amplified Polymorphic DNA (RAPD) fingerprinting
• Antimicrobial susceptibility testing
• Detection of antimicrobial resistance integrons and Salmonella virulence plasmid (pSV)

Main Results:

• Eight Salmonella serovars were identified, with Enteritidis, Typhimurium, and Typhi being most prevalent.
• Most isolates (74%) were susceptible to common antimicrobial drugs, but 37% showed intermediate susceptibility to ciprofloxacin.
• Antimicrobial resistance integrons were found in one Dublin and two Infantis isolates.
• The Salmonella virulence plasmid (pSV) was detected in all Enteritidis, Typhimurium, Choleraesuis, and Dublin isolates.

Conclusions:

• Multiplex PCR serotyping can effectively replace classic serotyping.
• MLST, particularly sequencing of one or two loci, is a valuable confirmatory tool.
• Molecular typing provides essential insights into Salmonella epidemiology and antimicrobial resistance in Peru.