AFAIK, there is no such option with minted. But with listings it is easy. you can use
escapechar=!, %% use any character as you wish
or
moredelim=[is][\bfseries\color{magenta}]{`}{`}, %% same as above
Or
escapeinside={*@}{@*} %% Use as *@ \bfseries class @*
etc.
Here is some sample:
\documentclass[a4paper,11pt]{article}
\usepackage{xcolor}
\usepackage{courier}
\usepackage{listings} % for code snippets
\definecolor{dkgreen}{rgb}{0,0.6,0}
\definecolor{gray}{rgb}{0.5,0.5,0.5}
\definecolor{mauve}{rgb}{0.58,0,0.82}
\lstset{frame=single,
framerule=0pt,
backgroundcolor=\color{olive!10},
language=Java,
aboveskip=3mm,
belowskip=3mm,
showstringspaces=false,
columns=fullflexible,
basicstyle={\footnotesize\ttfamily},
numbers=left,
numbersep=10pt,
numberstyle=\scriptsize\color{gray},
keywordstyle=\color{blue},
commentstyle=\color{dkgreen},
stringstyle=\color{mauve},
escapechar=!,
moredelim=[is][\bfseries\color{magenta}]{`}{`},
breaklines=true,
breakatwhitespace=true,
tabsize=2
}
\begin{document}
\begin{lstlisting}[escapechar=!,]
!\bfseries\color{blue} class! Test
{
public static void main(String args[])
{
System.out.println("Hello World");
}
}
`class`
\end{lstlisting}
\end{document}

minted, which delegates the job to Pygmentize and its lexers. A Python forum would be better, I guess. – egreg Jun 01 '14 at 07:36classis already printed boldface; try adding\usepackage[lighttt]{lmodern}to realize it. The fact is that the usual Computer Modern Typewriter fonts don't have a boldface variant. – egreg Jun 01 '14 at 08:49