by Sean Elliott, MD

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    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.

    About the Lecture

    The lecture Haemophilus by Sean Elliott, MD is from the course Bacteria.

    Included Quiz Questions

    1. Staphylococcus aureus
    2. Streptococcus pyogenes
    3. Escherichia coli
    4. Neisseria gonorrhoeae
    5. Proteus mirabilis

    Author of lecture Haemophilus

     Sean Elliott, MD

    Sean Elliott, MD

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