Prevalence of in Bangladesh: Isolation and Characterization of a Rare Phage MK-13 That Can Robustly Identify Shigellosis Caused by Type 1

Shigellosis, caused by type 1, is understudied and underreported. For 3 years, GEMS study identified 5.4% of all as . We showed the prevalent serotypes of in Bangladesh and phage-based diagnosis of type 1, a rapid and low-cost approach. Previously typed 793 clinical strains were used for serotype distribution. Twenty-eight environmental water samples were collected for isolation of phages. Forty-eight serotypes of and other enteric bacteria were used for testing the susceptibility to phage MK-13. Electron microscopy, restriction enzyme analysis, whole genome sequencing (WGS), and annotation were performed for extensive characterization. type 1 is the second most prevalent serotype among 20 serotypes of in Bangladesh. We isolated a novel phage, MK-13, which specifically lyses type 1, but doesn't lyse other 47 serotypes of or other enteric bacteria tested. The phage belongs to the family and distinct from other phages indicated by electron microscopy and restriction enzyme analysis, respectively. MK-13 genome consists of 158 kbp of circularly permuted double-stranded DNA with G + C content of 49.45%, and encodes 211 open reading frames including four tRNA-coding regions. The genome has 98% identity with previously reported phage, ΦSboM-AG3, reported to have a broader host range infecting most of the and other species of tested. To our knowledge, MK-13 is the first phage reported to be used as a diagnostic marker to detect type 1, especially in remote settings with limited laboratory infrastructure.