Haemophilus

00:01 Haemophilus, a bacteria.

00:04 The Haemophilus are small, gram-negative, pleomorphic, coccobacilli.

00:09 The Haemophilus grow aerobically or occasionally facultatively anaerobically, but they also are known to be obligate parasites of mucous membranes.

00:18 That's where they live, that's where they colonize, that's where they can actually be acquired from to create infection.

00:25 Importantly, the Haemophilus require either hemin factor X or factor V for growth. .

00:33 This factor is present in chocolate agar which is the most typical way of growing Haemophilus influenzae.

00:41 However, to grow Haemophilus on blood agar, one also has to grow staphylococcus aureus.

00:47 Haemophilus influenzae cultures most readily on chocolate agar, which is essentially a blood agar with lysed red blood cells. The reason for this is that standard blood agar lacks the NAD required to culture h flu.

01:01 Interestingly, however, you can co culture staph aureus and h flu together on routine blood agar because the staff organism actually produces NAD as a metabolic byproduct and the h flu can then grow as satellite colonies in that space created by the staph aureus.

01:19 This is demonstrated by the picture on the right side of the slide where staph aureus is streaked out that that line across the middle of the blood agar.

01:27 And you can see Haemophilus influenza as point satellite colonies growing right close to it.

01:32 The medically relevant species we will talk about with Haemophilus are Haemophilus influenzae and Haemophilus ducreyi.

01:40 Now, Haemophilus influenzae sure sounds a lot like influenza, the virus which we know about causing the flu.

01:48 And in fact for the longest time historically, the illness which we know as influenza was thought to be caused by a bacteria which was the Haemophilus.

01:59 Hence, it took its name from the historical disease association.

02:03 We now know that of course bacterial disease caused by Haemophilus influenzae does not cause the flu at all, but it can cause secondary sinopulmonary infections.