Evaluation of the impact ofShigellavirulence genes on the basis of clinical features observed in patients with shigellosis

AbstractShigellais still attributable to nearly 164,300 deaths annually, mostly in sub-Saharan Africa and South Asian young children, remaining as a major public health threat, especially in the developing countries. Our goal was to study the association betweenShigellavirulence genes and clinical features observed in shigellosis. Therefore, 61S. flexneristrains were investigated, isolated from patients from a tertiary level facility in Bangladesh between 2009 to 2013. Subsequently, the presence of 140 MDa large virulence plasmid (p140), virulence (ipaH, ial), toxin (set, sen) and T3SS related genes (virB, ipaBCD, ipgC, ipgB1, ipgA, icsB, ipgD, ipgE, ipgF, mxiH, mxiI, mxiK, mxiE, mxiC, spa15, spa47, spa32andspa24) were evaluated. p140 was found in 79% (n=48) cases.ipaBCDwas found in 90% (n=55) strains, while seven of them were missing p140. However,ialwas found in 89% isolates, andipgCandipgEin 85% cases. The prevalence of the rest of the genes was less than 85%. These findings were then compared against the clinical features of each of the corresponding pathogens, and several statistically significant correlations were observed (all p<0.05). Briefly, the enterotoxin genes (set, sen) and another virulence gene (ial) were found significantly associated with several clinical features of shigellosis, including bloody mucoid stool, rectal straining, fever, and abdominal pain. Our findings reiterate that the diarrheal disease severity is significantly associated with the enterotoxin producingShigellainfection, also suggesting that the T3SS related virulence genes might be translocated elsewhere other than the 140 MDa large virulence plasmid.