0:02 welcome to section 8 of bacteria this is
0:04 our bacteria overview figure in this
0:05 video we'll be discussing
0:08 carinibacterium diphtheriae which you
0:09 can see right here quranibacterium
0:12 diphtheriae sounds kind of like corn so
0:14 we thought a haunted corn maze scene
0:15 would work well to help you remember
0:17 this organism as you can see from the
0:18 image this corn maze is getting shut
0:21 down but why by the end of the video it
0:23 will all make sense before we go any
0:24 further pay attention to the background
0:26 that's right there's a purple looking
0:28 sunset just like in our other videos
0:29 this should help you remember that
0:31 quranic bacterium diphtheriae is gram
0:34 positive this is an actual gram stain of
0:36 qurani bacterium diphtheriae notice that
0:38 the organism appears purple hence the
0:40 gram positive classification but it's
0:42 also rod shaped which is why it's a
0:45 bacillus the shape is a bit unique
0:47 because it looks kind of like a club you
0:49 can see this pretty obviously right here
0:51 notice that there's a prominent end on
0:53 the organism right here okay with this
0:55 in mind let's return to the story the
0:56 corn maze is being shut down because
0:59 this poor kid has lice all over his head
1:00 which he contracted while he was in the
1:02 corn maze his mother wasn't too happy
1:04 about this so she's on the phone
1:05 complaining about how this terrible
1:07 business needs to be shut down we've
1:09 shown lice on this kid's head because it
1:11 sounds kind of like lysogenic this part
1:12 of the scene should help you remember
1:14 that carinibacterium diphtheriae must
1:17 first be lysogenized by a bacteriophage
1:19 before it produces a virulent exotoxin
1:21 simply put this just means that a virus
1:24 which codes for the diphtheria exotoxin
1:26 must integrate its nucleic acid into the
1:28 bacterium's genome in order for the
1:30 bacterium to become dangerous so again
1:33 lys for lysogenized also notice that the
1:35 mom is extremely distressed about this
1:37 whole situation that's why she's using
1:39 her asthma inhaler to get more oxygen
1:41 and attempt to calm her down we've used
1:43 the inhaler in other videos to represent
1:45 aerobic organisms but let me refresh
1:47 your memory inhalers are commonly used
1:50 by asthmatics to facilitate oxygen
1:52 delivery to the lungs so it can be
1:53 thought of as a symbol for aerobic
1:55 organisms which are bugs that grow well
1:57 in the presence of a lot of oxygen so
1:59 the asthma inhaler in this image should
2:01 help you remember that crinobacterium
2:04 diphtheriae is an aerobic organism
2:06 finally notice that she's using her
2:09 telephone to tell the agency about how
2:10 her son got lice in this filthy corn
2:13 maze telephone and tell sound kind of
2:16 like telluride agar so these two ideas
2:17 should help you remember that the
2:20 organism can be grown on telluride agar
2:22 this is an image of cystine telluride
2:24 agar telluride is just a mineral that is
2:26 used in the agar notice that there are
2:28 black colonies that can be seen in the
2:31 image this is most apparent right here
2:33 okay moving on notice that we've added a
2:35 guy in an alien costume next to the corn
2:37 maze this shouldn't be too surprising
2:39 this is a haunted corn maze after all so
2:41 a scary looking alien guy seems pretty
2:43 fitting anyways we've included this
2:44 alien guy in the image to help you
2:46 remember that aniline dyes are used to
2:49 stain metachromatic granules red and the
2:51 rest of the cell blue metachromatic
2:53 granules are inclusions seen within the
2:55 organism that can be used during atp
2:58 synthesis so again alien for aniline
3:00 dyes if you look towards the back of the
3:02 image you can see that there is mist
3:03 near the corn maze we'll be using mist
3:05 to represent that an organism is
3:06 transmitted through aerosolized
3:08 respiratory droplets because mist
3:10 carries water molecules just like
3:12 respiratory droplets carry pathogens
3:14 okay now let's talk about the guy in the
3:16 booth notice that he's pulling on his
3:17 tie from all of the stress of his
3:19 business being shut down the tie wraps
3:21 around the neck and the fact that he's
3:23 pulling on it should help you remember
3:25 that karani bacterium diphtheriae causes
3:27 pharyngitis now you can see why he's so
3:29 stressed out this guy with a bureau
3:31 shirt on is handcuffing him must be a
3:33 pretty serious crime to have your
3:35 business infested with lice this part of
3:36 the scene should help you remember
3:38 details about the diphtheria toxin this
3:41 toxin has two subunits an a subunit and
3:44 a b subunit the letter b in bureau on
3:46 this guy's shirt is here to help you
3:48 remember that this part of the scene is
3:50 about the b subunit of the toxin the b
3:53 subunit binds to host cell receptors and
3:56 induces endocytosis of the toxin to help
3:57 you remember the function of the b
3:59 subunit we've shown the bureau guy
4:01 handcuffing the business owner just like
4:03 b subunit binds to the host cell this
4:05 bureau guy is binding the business owner
4:07 with handcuffs okay now let's discuss
4:09 the a subunit of the toxin to help you
4:11 remember this we've shown another guy in
4:14 a shirt that says agency the a in agency
4:15 should help you remember that this part
4:17 of the scene is about the a subunit the
4:20 a subunit inhibits host cell protein
4:22 synthesis by inhibiting elongation
4:25 factor 2 or ef2 during elongation of
4:26 protein synthesis to help you remember
4:29 this we've shown the agency guy using an
4:31 extendable baton to silence this group
4:34 of protesters so extendable baton for
4:36 inhibits elongation factor two also
4:38 notice that for your entertainment we've
4:40 shown this cowardly man running away
4:42 from the scary alien right here he
4:43 doesn't really mean anything
4:45 specifically but hopefully he'll help
4:46 you remember the alien in the image
4:48 which is ultimately here to help you
4:49 remember that aniline dyes are used to
4:52 stain metachromatic granules red and the
4:54 rest of the cell blue as we discussed
4:55 earlier now we've added some heat lamps
4:57 to the scene businesses commonly use
4:59 these outdoors to help keep their
5:01 customers warm so it seems pretty
5:03 fitting the heat lamps generate heat
5:05 just like someone with a fever generates
5:07 a lot of heat so we've included these to
5:08 help you remember that a fever may be
5:11 seen in infected patients next notice
5:12 that we've included some tires in the
5:14 background just like we did in our c
5:16 diff image the tires are circular and
5:18 resemble the cell membrane i guess you
5:19 could say they're kind of like a
5:21 membrane but not quite so
5:23 pseudomembranes these should help you
5:24 remember that a pseudo-membrane is
5:26 classically seen in the pharynx on
5:28 physical examination this is an image of
5:30 what the pseudomembrane looks like as
5:32 you can see it's a grayish white
5:33 substance that has adhered to the
5:35 posterior pharynx right here
5:37 okay now let's turn our attention to the
5:38 other agency guy in the back of the
5:40 scene who's closing off the corn maze
5:42 with a rope if you look closely at the
5:43 rope you can see that it looks kind of
5:45 like sausage links this resembles the
5:48 myelin sheath around an axon so we've
5:49 shown it in this image to help you
5:51 remember that crying bacterium
5:53 diphtheriae is neurotoxic all of these
5:55 agents didn't walk here they came here
5:56 in their car which you can see on the
5:58 left side of the image the car should
6:00 help you remember that the organism is
6:02 also cardiotoxic this may be manifested
6:05 as myocarditis heart block and
6:08 arrhythmias so car for cardiotoxic we've
6:10 also shown this elk in the background
6:11 who's looking for some food looks like
6:13 he's found a big field of corn that's
6:15 ready to be eaten elk sounds kind of
6:17 like elic so we've included it in this
6:19 image to help you remember that an elic
6:22 test can be used to identify toxogenic
6:24 from non-toxigenic strains of qurani
6:26 bacterium diphtheriae next notice that
6:28 this guy is laughing laughing sounds
6:31 like loffler's media so we've included
6:32 him to help you remember that carine
6:35 bacterium diphtheriae can be cultured in
6:37 lofler's medium where the metachromatic
6:39 granules may be seen more easily okay so
6:41 why was this guy laughing in the first
6:43 place as you can see he's not a fan of
6:45 the feds so he's laughing while his
6:48 friend pops the fed's tires if you look
6:49 closely you can see that this guy in the
6:51 green shirt is using a syringe to pop
6:53 the tires just like in other videos a
6:55 syringe is our symbol for a vaccine so
6:57 this part of the scene should help you
6:59 remember that there is a toxoid vaccine
7:01 which can prevent diphtheria you'll
7:03 often hear tdap or dtap which is a
7:06 combination of multiple vaccines and
7:07 this is how the vaccine is usually given
7:09 so again guy popping car tires with a
7:12 syringe for vaccine finally we've shown
7:14 the car suspended by little y-shaped
7:16 suspension tools that look kind of like
7:17 immunoglobulins this is to help you
7:19 remember that if an unimmunized
7:21 individual becomes infected then
7:23 pre-formed antibody can be administered
7:25 to help prevent systemic complications
7:27 okay now that we've covered the image
7:28 let's review with a question a 12 year
7:30 old boy who recently moved to the united
7:32 states from nepal is brought to the
7:34 emergency department due to fever
7:36 pharyngitis and heart palpitations his
7:38 temperature is 38.5 degrees celsius but
7:40 other vital signs are normal physical
7:42 examination is significant for a great
7:45 exudate on the posterior pharynx a swab
7:47 of the exudate is obtained on microscopy
7:49 there are gram-positive rods with
7:51 granules that stain deeply with aniline
7:53 dyes he is admitted to the hospital
7:55 which of the following should be done
7:57 immediately to prevent additional
8:00 complications a careful monitoring of
8:03 neurological status b intubation c
8:05 serial electrocardiograms
8:08 d pre-formed anti-toxin administration
8:10 or e vaccine administration okay
8:11 hopefully from the question stem you
8:13 notice that this boy's presentation is
8:15 consistent with chronic bacterium
8:16 diphtheriae a few points from the
8:18 question stem that are suggestive of
8:20 this diagnosis include a recent move
8:23 from nepal which suggests a lack of
8:25 immunization a great exudate on the
8:28 posterior pharynx and gram positive rods
8:30 with granules that stain deeply with
8:33 aniline dyes the exudate is describing
8:34 the pseudomembrane we talked about
8:37 earlier this is a pretty important point
8:39 questions on the actual step one test
8:41 we'll commonly avoid buzzwords like
8:42 pseudomembranes and instead we'll
8:45 describe the pseudomembrane so for
8:47 example a gray exudate on the posterior
8:49 pharynx okay with this in mind we're
8:51 asked what should be done immediately to
8:53 prevent additional complications the
8:55 correct answer is d pre-formed
8:58 anti-toxin administration the anti-toxin
9:00 contains neutralizing antibodies that
9:03 inactivate the diphtheria toxin however
9:05 the anti-toxin is only useful before
9:07 toxin enters the cell so it must be
9:10 administered immediately a is a good
9:11 idea and should eventually be done
9:14 because diphtheria is neurotoxic however
9:16 administration of pre-formed antitoxin
9:19 is more important because any delay may
9:20 allow more of the toxin to enter the
9:23 cells b is unnecessary at this point
9:25 because the boy's respiratory rate is
9:28 normal so he doesn't appear to be in any
9:30 respiratory distress however careful
9:32 airway management is important because
9:34 the pseudomembrane may cause airway
9:37 obstruction so b is incorrect c is also
9:39 a good idea because diphtheria is
9:41 cardiotoxic but just like a
9:43 administration of the antitoxin is more
9:45 important so c is incorrect e should
9:47 also be done but the immune response to
9:49 vaccination is slow therefore the
9:51 antitoxin should be given first in
9:53 someone who is acutely ill and then
9:55 vaccine administration can be given
9:58 later so e is also incorrect
10:00 from the image recall that the little y
10:02 shaped suspension tools under the car
10:04 that look kind of like immunoglobulins
10:07 represent the pre-formed antibody or
10:09 anti-toxin which should be administered
10:11 to prevent systemic complications in
10:13 acutely ill patients and with that we've
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