Scrutinising the Efficacy of Enterococcus faecalis CRISPR Typing in Malaysian Isolates

This study asserts that a combined CRISPR locus analysis offers a cost-effective alternative to established genotyping methods, yet the sample size remains a significant constraint. The investigation focused on 26 Enterococcus faecalis isolates collected from diverse settings in Segamat, Malaysia. The core objective involved developing specific primers to target the CRISPR1-cas loci.

While three major loci exist in this species, the team specifically assessed Enterococcus faecalis CRISPR typing protocols on the CRISPR1 and CRISPR2 arrays. Of the collected samples, 50% harboured the CRISPR1-cas9 locus. Amplification proved successful in 12 of the 13 isolates containing the cas9 gene, demonstrating technical feasibility within this limited cohort.

Characterisation revealed that while CRISPR1-cas shares array length and repeat sequences with CRISPR2, spacer identities and terminal repeat (TR) sequences differ markedly. Most spacers encoded for chromosomal DNA rather than foreign genetic elements. Interestingly, genotypes based on ancestral spacers (AS) showed distinct lineage patterns; isolates sharing a CRISPR1-AS genotype did not necessarily align with the same CRISPR2-AS genotype. This divergence highlights the complexity of relying on a single locus for strain differentiation.

Validating Enterococcus faecalis CRISPR typing against MLST

The authors propose that combining CRISPR1-cas and CRISPR2 typing provides discriminatory power comparable to Multilocus Sequence Typing (MLST). If validated in larger cohorts, this approach could facilitate short-term epidemiological surveillance with lower sequencing costs. However, the study currently serves primarily as a genetic reference for Southeast Asia. The claim of equivalence to MLST requires rigorous testing against a broader global dataset before it can replace current gold standards.