Genomic Analysis and Resistance Mechanisms in Shigella flexneri 2a Strain 301

Area of Science:

• Microbiology and Genetics
• Genomics and Bioinformatics
• Infectious Diseases

Background:

• Shigella flexneri causes shigellosis, a significant disease in developing nations.
• Antibiotic resistance, particularly multidrug resistance (MDR), poses a major global health challenge.
• Molecular mechanisms underlying bacterial MDR remain incompletely understood.

Purpose of the Study:

• To investigate the genomic basis and evolution of antibiotic resistance in Shigella flexneri.
• To identify specific genetic mutations conferring resistance to ciprofloxacin (CIP), ceftriaxone (CRO), and tetracycline.
• To understand the molecular mechanisms driving MDR in this pathogen.

Main Methods:

• Whole-genome sequencing of Shigella flexneri populations under sequential antibiotic selection.
• Identification and analysis of chromosomal antibiotic resistance genes.
• Detection of single nucleotide polymorphisms (SNPs) associated with MDR and single-drug resistance.

Main Results:

• 82 chromosomal antibiotic resistance genes were identified.
• 40 SNPs in 8 genes and 3 intergenic regions, including mutations in metG, were consistently found under all three antibiotic pressures.
• Nonsynonymous mutations in gyrB, ydgA, rob, and narX were observed under CIP or CRO selection.

Conclusions:

• Genomic analysis successfully identified key mutations contributing to antibiotic resistance in Shigella flexneri.
• Specific SNPs in genes like metG, gyrB, and rob are crucial for developing MDR.
• Judicious selection and use of antimicrobial agents are essential for effective shigellosis treatment and combating resistance.