In this video, I will go through buzzwords and associations having to do with microbiology. This will mostly be for bacteria more than any other type of pathogen. This video is not going to really contain in-depth explanations about pathophysiology or normal physiology. It's more so intended to be a

rapid review of high-yield buzzwords and associations that you really need to know. So let's get started with the normal flora by location. So on the skin, you want to think about *Staphylococcus epidermidis*. In the nose, both *Staphylococcus epidermidis* and *Staphylococcus aureus*. In

the oropharynx, *Streptococcus* in the colon, *Bacteroides fragilis* and *E. coli*, and in the vagina, *Lactobacillus*, Group B *Streptococcus*, and *E. coli*. Food-borne illnesses. So as you'll see in this table, there's lots of different types of meats and

associations with meats. So we'll we'll kind of talk about that at the end, but don't get too confused here. In reheated rice, be on the lookout for *Bacillus cereus*. Improperly canned foods, *Clostridium botulinum*. Reheated meat, *Clostridium perfringens*. 

Undercooked meat, *E. coli*, and specifically be on the lookout for the O157:H7 subtype. Deli meats and soft cheeses, *Listeria monocytogenes*. So basically, if whatever the meat is would appear on a charcuterie board, an appetizer plate, 

anything that you'd see at a dinner party, then you want to think *Listeria*. Poultry meat in general or eggs, think *Salmonella*. Now, I understand that this says meat and you're like, well what kind of meat is it? Undercooked, reheated filet mignon, T-bone, like I I know that there's

lots of different types of meat here so if the test writer wants you to go for salmonella they're going to give you other clues so don't rely just on the word meat but of all of these options deli meat is the one that's kind of most

pathogenic so if you see deli meat that's clearly the area but if you see meat in general the test writer has to give you other clues so try not to get too overwhelmed meat and mayo so that's going to be staphylococcus and usually the

test writer for staphylococcus will give you some type of food if they're going after a foodborne illness they'll give you some some type of food that has mayonnaise and that was left out at say a picnic or a barbecue or something to

say that this mayo containing food was left out in the heat so it could be potato salad macaroni salad anything that has mayo mixed into it so I know that we're not in culinary school but you do need to know your foods and lastly seafood think vibrio

vulnificus this table is going to talk about the comorbid history clues so in a lot of patients depending on what type of medical problem they have that medical problem predisposes them to getting a certain infection because the infection the pathogen most cases in this

table you're going to see uh bacteria takes advantage of somebody's lack of immunity in one way or another so if you see somebody who has alcoholism you want to think about klebsiella and this kind of goes hand in hand with the third

row that you see which says aspiration pneumonia so any type of disease or illness that makes somebody altered or more likely to aspirate you want to think about Klebsiella or you want to think about your anaerobic robes and that can

be alcoholism so if somebody's drunk they're more likely to aspirate that can be dementia if somebody sleeps on the couch at 3:00 p.m. with their head cocked all the way back they're more likely to aspirate that could be delirium if

somebody's in a hospital setting and they get hospital-acquired delirium they're more likely to aspirate so in all of the common denominator in all of these comorbid disease processes is that someone who's more likely to aspirate think your anaerobic robes IV drug abuse the

biggest association is Staph aureus so if you see somebody who on your test maybe the test writer will say in the vignette has a three-year history of intravenous drug abuse be mentally prepared for a question that sounds like it's being framed to test you on substance abuse

switching or transitioning into a third-order question where they want you to go after Staph aureus and either identify an associated finding the pathophysiology of Staph aureus the treatment etc. Cystic fibrosis the biggest association is Pseudomonas however you should also know

Burkholderia and Staph aureus but if you see cystic fibrosis and you have to pick just one answer pick Pseudomonas as your associated pathogen anybody who's immunocompromised you always want to think about Staph aureus and if you have any

health care experience, you know that the big, the big Healthcare-acquired infection that we worry about is MRSA and staff infections in general. So if somebody's immunocompromised in a health care setting, then obviously staph aureus is a big concern, but also nosocomial pneumonia.

That's a big one, Hospital-acquired infection, so kind of what I just talked about again, staph aureus, big one, but also nosocomial Pseudomonas. On the test, Pseudomonas tends to be the answer, in real life it's staph aureus, and then post-viral status. So on

your exam, if the test writer tells you in the vignette, um, patient has a past medical history of, for example, diabetes mellitus, hypertension, hypothyroidism, and a recent resolving infection over the past 7 days, what they're telling you in that

vignette is that the patient had some type of unknown viral illness. Maybe they'll tell you exactly what it was, maybe they won't. That really doesn't matter, but what they're hinting at is that they're getting over a virus and now they're more likely to have a

bacterial infection, and the biggest, most common one is Strep pneumonia causing a post-viral bacterial pneumonia. So if on your exam somebody had some type of viral illness and then the test writer gives you respiratory symptoms, the answer is Strep pneumonia. You can also

see this with staph aureus and H. influenza, but the big one is Strep pneumonia. Now let's do some health care-associated buzzwords. So recent antibiotic use, you want to pick C. diff. Again, the test writer will tell you in

the question and it's going to sound like a distractor, but it's there for a reason. The patient has a past medical history of A and C and recently was treated for blank, and they're not going to tell you that they were on an

antibiotic, but they're going to allude to it by saying recently was treated for blank. And when the test writer puts that in the vignette, red flags need to go off in your head, the alarm bells need to ring, and you want to be on the lookout

for GI symptoms and C. diff because when you take that antibiotic, you're also removing the normal flora in the gut, and when that happens, you're more likely to get C. diff. Altered mental status, again, we kind of already talked about this. Anybody who's altered and therefore

more likely to aspirate. You want to be on the lookout for the Anor robes ulcers, wounds, and surgical drains. The big concern again, it's kind of healthcare-related. Staff orius, intravascular catheters. Well, same thing, staff orius

however, specific to intravascular catheters. And what shows up a lot on exams is Staff epidermitis. So be able to differentiate the associated findings of Staff orius with the associated findings of Staff epidermus because if the test

writer tells you that the patient has an intravascular catheter in place, you're really picking between these two. And the ability to parse through that depends on looking through the rest of the vignette and saying what else did the test writer give me? Is it more consistent with

epidermidis or more consistent with oropharyngeal intubation or mechanical ventilation. So again, we're seeing a theme here: ventilation, intubation, things that make you more likely to aspirate or have the introduction of bacteria through the respiratory tree.

Klebsiella, however, you also need to be aware that Pseudomonas is a big concern here as well. Anybody who's on dialysis, you want to think Hepatitis B or Hepatitis C. Anybody who has a urinary catheter in place, big, big high-yield finding that's

associated with a urinary catheter is Proteus as well as E. coli, and those are fairly different in terms of what else the test writer would give you. So be able to differentiate Proteus versus E. coli for urinary catheters just like you should be able to differentiate

Staphylococcus aureus versus Staphylococcus epidermidis for intravascular catheters. And then lastly, anytime that water can become aerosolized, think Legionella. Historically, this shows up on tests with like HVAC-related things, so air conditioners or um, window unit, the

window units that are air conditioners, but it's really anything where water becomes aerosolized, so that's going to be associated with Legionella. All right. Now there are also zoonotic associations that will help you on your exam if you're able to associate either the animal or

the reservoir with the pathogen. So let's fly through these: Iodes tick associated with Anaplasma, cats with Bartonella, the Iodes tick again or deer or mice, and deer or mice in this case is the reservoir that's Babesia. B. burgdorferi is

associated with brucella rentis unpasteurized dairy kind of randomly in place here but that's associated with brucella because again that's zoonotic pet feces you want to associate that with campylobacter parrots with chlamydia psittaci

and cattle or sheep and specifically it's the amniotic fluid of the cattle or the sheep that's associated with coxiella burnetii the lone star tick that's associated with ehrlichia chaffeensis the rabbit or the deerfly that's associated with francisella

tularensis water um or water that has urine in it that's associated with leptospira so leptospirosis the arm D that's associated with mycobacterium leprae cat dog or animal bite that's associated with pasteurella

multocida the body louse that is associated with rickettsia prowazekii dermacentor that sounds so scary the dog tick dermacentor that's associated with rickettsia rickettsii fleas those are going to be associated with rickettsia typhi so

let me pause for a second you see that there are three different rickettsia body louse is prowazekii dog tick is rickettsii and fleas are typhi reptiles and poultry um associated with salmonella and then lastly prairie dogs

and fleas as well as rats which are the reservoir that's associated with Yersinia pestis or pestis excuse me and I think most of us are kind of familiar with that last one already because of rats lastly let's conclude by associating some disease findings with a

pathogen so osteomyelitis is associated with Staphylococcus aureus now specifically and I carved it out on its own uh row here because it's very important osteomyelitis specifically in a patient with sickle cell disease that's going to be Salmonella and this is really important

if you're taking Step 2 level two or Step 3 level three if they ask you which of the following is the most likely causative pathogen and the test the the patient in question has osteomyelitis if they don't tell you it's sickle cell disease the answer is

Staphylococcus aureus and I want to take this one step further because this is very high yield even if they ask the question which of the following is the most likely causative pathogen from an epidemiological standpoint it is still more common for a patient with Salmonella

with for a patient with sickle cell who has osteomyelitis to get it from Staphylococcus aureus so I want to be really clear if they tell you that it is a patient with sickle cell who has osteomyelitis chances are on Step 1

level one they're going after Salmonella but on Step 2 level two or Beyond if they tell you that the patient has sickle cell and has osteomyelitis and asks you point blank with all else being equal without any other associations to Salmonella which is the most likely or

most common causative pathogen even though they have sickle cell it is still more likely for them to get osteomyelitis from Staphylococcus aureus and that is a very high yield fact for Step 2 level two and Beyond so I hope my explanation there was clear again still

more likely for osteomyelitis to be caused from *Staphylococcus aureus* even if the patient has sickle cell disease. However, if the patient has sickle cell disease and has osteomyelitis, chances are they could go after *Salmonella*. Now, osteomyelitis in intravenous drug abuse

that's likely going to be caused from *Pseudomonas*. However, same thing, even if the patient is an IV drug abuser and even if they have osteomyelitis, if the question asks you what the most likely causative pathogen is, it's still *Staphylococcus aureus*. 

So *Staphylococcus aureus* equals osteomyelitis, that's the most common cause, but in sickle cell disease think *Salmonella*, and in IV drug abuse think *Pseudomonas* because on Step 1 level 1, that's where they're going to go. Myocarditis is *Coxsackie B*. Kidney

stones you want to think of *Klebsiella*. Bacterial meningitis in adults think *Streptococcus pneumoniae*, but bacterial meningitis in newborns think Group B strep. Now, same deal here just like we talked about with osteomyelitis. If they ask you which of

the following is the most likely or most common causative pathogen from an epidemiological standpoint, *Streptococcus pneumoniae* is the answer. It doesn't matter if they're an adult or if they're a newborn. If the question is simply asking you about epidemiology, pick *Streptococcus pneumoniae*. 

So be able to differentiate that. If you're at the Step 2 level 2 or Step 3 level 3 point in your career, urinary tract infection, *E. coli*, and temporal lobe encephalitis, HSV-1. Now, that does it for this video.

again sort of a rapid review just to put some associations in your brain this might help you if you're nearing the end of your studying period or if you're in the beginning of your studying period and you're trying to assess your readiness or how prepared you are to

Microbiology Buzzwords & Associations

Dirty Medicine

Normal Flora by Location and Foodborne Illnesses

Skin: Staphylococcus epidermidis; Nose: S. epidermidis and S. aureus; Oropharynx: Streptococcus; Colon: Bacteroides fragilis and E. coli; Vagina: Lactobacillus, Group B Streptococcus, and E. coli.

Reheated rice: Bacillus cereus; Improperly canned foods: Clostridium botulinum; Reheated meat: Clostridium perfringens; Undercooked meat: E. coli O157:H7.

Deli meats and soft cheeses: Listeria monocytogenes; Poultry/eggs: Salmonella.

Meat and mayonnaise: Staphylococcus; Seafood: Vibrio vulnificus.

Comorbid History Clues and Associated Pathogens

Alcoholism: Klebsiella (aspiration pneumonia); Dementia, delirium: Anaerobic bacteria (aspiration pneumonia).

IV drug abuse: Staphylococcus aureus; Cystic fibrosis: Pseudomonas, Burkholderia, Staphylococcus aureus.

Immunocompromised: Staphylococcus aureus, nosocomial pneumonia, Pseudomonas; Post-viral status: Streptococcus pneumoniae.

Healthcare-Associated Buzzwords and Pathogens

Recent antibiotic use: Clostridium difficile; Altered mental status: Anaerobic bacteria (aspiration pneumonia).

Ulcers, wounds, surgical drains: Staphylococcus aureus; Intravascular catheters: Staphylococcus aureus, Staphylococcus epidermidis.

Dialysis: Hepatitis B or C; Urinary catheter: Proteus, E. coli; Aerosolized water: Legionella.

Ixodes tick: Anaplasma, Babesia; Cats: Bartonella; Unpasteurized dairy: Brucella.

Pet feces: Campylobacter; Parrots: Chlamydia psittaci; Cattle/sheep amniotic fluid: Coxiella burnetii.

Lone star tick: Ehrlichia chaffeensis; Rabbit/deerfly: Francisella tularensis; Water with urine: Leptospira.

Armadillo: Mycobacterium leprae; Cat/dog bite: Pasteurella multocida; Body louse: Rickettsia prowazekii.

Dog tick: Rickettsia rickettsii; Fleas: Rickettsia typhi; Reptiles/poultry: Salmonella.

Disease Findings and Associated Pathogens

Osteomyelitis: Staphylococcus aureus (most common); Osteomyelitis in sickle cell disease: Salmonella; Osteomyelitis in IV drug abuse: Pseudomonas.

Myocarditis: Coxsackie B; Kidney stones: Klebsiella; Bacterial meningitis in adults: Streptococcus pneumoniae.

Bacterial meningitis in newborns: Group B Streptococcus; Urinary tract infection: E. coli; Temporal lobe encephalitis: HSV-1.