Comparison of CRISPR typing and conventional molecular methods for distinguishing Laribacter hongkongensis isolates from fish, frogs and humans.

High-resolution and efficient typing for Laribacter hongkongensis (L. hongkongensis) is essential for epidemiological investigation of such emerging foodborne pathogens. Clustered regularly interspaced short palindromic repeats (CRISPR) typing is an innovative molecular method that shows great promise for L. hongkongensis typing. Here, we explored the CRISPR typing method by combining CRISPR1 and CRISPR2 loci to characterize a collection of 109 L. hongkongensis isolates from humans and animals and compared it to current molecular methods such as pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The results showed that all three methods have high discriminatory power (diversity index was 0.9902 for PFGE, 0.9663 for CRISPR and 0.9562 for MLST); strong congruence was observed between them (Rand index was 0.969 between CRISPR and PFGE, 0.953 between CRISPR and MLST, 0.958 between PFGE and MLST). CRISPR typing could well distinguish the isolates in the same STs or PFGE profiles, and the genetic information contained by the CRISPR array is useful for deep phylogenetic typing. We demonstrate that rapid CRISPR typing is a practical genetic fingerprinting tool with high resolution, comparable ease of use and lower cost, ability to track the source of various groups of L. hongkongensis strains and indication of genetic characteristics.