documentclass[a4paper,11pt]{book}
usepackage{fancyhdr}
pagestyle{fancy}
fancyhead{}
fancyfoot{}
fancyhead[L]{textsl{leftmark}}
fancyfoot[L]{textsl{rightmark}}
usepackage{lipsum}
begin{document}
chapter{Chapter name with capital text and Escherichia coli }
lipsum[2-4]
section{Section name with  Escherichia coli}
lipsum[2-4]
end{document}