<p><b><span style="color: #000000">[[Haemophilus influenzae]],</span></b><span style="color: #000000"><b>influenzae]]</b>, &nbsp;formerly called <b>Pfeiffer's bacillus</b> or <i><b>Bacillus influenzae</b></i>, is a non-motile Gram-negative rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the <i>Pasteurellaceae</i> family, it is generally aerobic, but can grow as a facultative anaerobe.<sup id="cite_ref-KuhnertChristensen_0-0" class="reference"><font size="2">[1]</font></sup> <i>H. influenzae</i> was mistakenly considered to be the cause of influenza until 1933, when the viral etiology of the flu became apparent. Still, <i>H. influenzae</i> is responsible for a wide range of clinical diseases.</span></p>