AUTHOR=Akter Mahmuda , Brown Nathan , Clokie Martha , Yeasmin Mahmuda , Tareq Tokee M. , Baddam Ramani , Azad Muhammad A. K. , Ghosh Amar N. , Ahmed Niyaz , Talukder Kaisar A. 

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

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02461

DOI=10.3389/fmicb.2019.02461

ISSN=1664-302X

ABSTRACT=<p>Shigellosis, caused by <italic>Shigella boydii</italic> type 1, is understudied and underreported. For 3 years, GEMS study identified 5.4% of all <italic>Shigella</italic> as <italic>S. boydii</italic>. We showed the prevalent serotypes of <italic>S. boydii</italic> in Bangladesh and phage-based diagnosis of <italic>S. boydii</italic> type 1, a rapid and low-cost approach. Previously typed 793 clinical <italic>S. boydii</italic> strains were used for serotype distribution. Twenty-eight environmental water samples were collected for isolation of <italic>Shigella</italic> phages. Forty-eight serotypes of <italic>Shigella</italic> 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. <italic>S. boydii</italic> type 1 is the second most prevalent serotype among 20 serotypes of <italic>S. boydii</italic> in Bangladesh. We isolated a novel phage, MK-13, which specifically lyses <italic>S. boydii</italic> type 1, but doesn’t lyse other 47 serotypes of <italic>Shigella</italic> or other enteric bacteria tested. The phage belongs to the <italic>Myoviridae</italic> 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 <italic>S. boydii</italic> and other species of <italic>Shigella</italic> tested. To our knowledge, MK-13 is the first phage reported to be used as a diagnostic marker to detect <italic>S. boydii</italic> type 1, especially in remote settings with limited laboratory infrastructure.</p>