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Medical Sciences > Lecture 5-Exam 2 > Flashcards

Lecture 5-Exam 2 Flashcards

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USMLE® Step 1 flashcards
1
Q

What are the gram positive bacili? (5)

A
  • Corynebacterium
  • Bacillus
  • Clostridium
  • Bacteroides
  • Lactobacillus
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2
Q

Corynebacterium:
* What is the morphology?
* Recognized as what type of disease? Who is it seen in?

A
  • Gram positive rods, aerobic, or facultatively anaerobic
  • Recognized as causing opportunistic disease in patients who are immunocompromised, have prosthetic devices, or have been in hospitals/nursing homes
  • Causes other diseases within sheep, goats, and other animals
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3
Q

What is C. Diphtheriae?

A

Primary cause of diphtheria – a disease which has essentially disappeared from developed countries after implementation of universal vaccination that targets the diphtheria toxin

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4
Q

What is this?

A

CORYNEBACTERIUM

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5
Q

Bacillus:
* What is the morphology?
* What type of bacteria, postive in what?

A
  • Gram positive, spore forming rod with motile flagella
  • Aerobic or facultative, catalase positive
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6
Q
  • What is special about bacillus anthracis?
  • What is a fun fact about bacillus?
A
  • is the only obligate bacillus pathogen in vertebrates-> Other species affect specific groups of insects
  • Fun fact: the 5th and 6th plagues of Egypt described in exodus are widely believed to have been anthrax
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7
Q

Bacillus species are used in what? What do they produce?

A
  • Bacillus species are used in many medical, pharmaceutical, agricultural, and industrial processes
  • Produce the antibiotics bacitracin and polymyxin (in neosporin)
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8
Q

What are the different bacillus bacteria we need to know and what do they cause? (3)

A
  • B. cereus: food poisoning (sitting in food warmers)
  • B. anthracis: anthrax. (cutaneous 95% of cases, intestinal anthrax aka ingesting spores, pulmonary anthrax aka inhaling spores)
  • B. thuringiensis and B. sphaericus: used as insecticide.
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9
Q

Clostridium:
* Responsible for many cases of waht?
* Have developed unique mechanisms for what?
* What do they cause?

A

Responsible for many cases of food spoilage.

Have developed unique mechanisms for survival linked to their protein toxins and spores
* Gas gangrene
* Food poisoning
* Pseudomembranous colitis

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9
Q

Clostridium:
* What is the morphology?
* Commonly found where?
* How many species?

A
  • Gram positive rods, anaerobic, endospore forming
  • Commonly found in soil, water, and gastrointestinal tract of insects, animals, and humans
  • Clostridium is largest genus with over 150 species.
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10
Q

What does C. botulinum, What does C. tetani and C. perfringens cause?

A

C. botulinum.
* Food spoilage (especially canned foods); botulism toxin.

C. tetani.
* Causes tetanus; tetanus toxin.

C. perfringens.
* Causes gas gangrene or food poisoning; variety of protein toxins

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11
Q

What is this?

A

Clostridium

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11
Q

What is this?

A
  • Right: B. cereus
  • Left: B. anthracis
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12
Q

What is this?

A

Clostridium botulinus

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12
Q

Bacteroides/lactobacillus:
* What is the morphology?
* What does it maintain? What happens when the bacteria escapes the enivironment?

A
  • Gram negative rods, anaerobic, non spore forming
  • Maintain a complex and generally beneficial relationship when retained in the gut, but when they escape this environment they can cause bacteremia and abscess formation
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13
Q
  • What area in the body has the largest population of bacteria?
  • What bacteria is 25% of bacteria?
A

Human colon has the largest population of bacteria in the body and approximately 25% are species of bacteroides

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14
Q

BACTEROIDES/LACTOBACILLUS:
* Is the morphologically simple or diverse?
* Usually what?
* What is the purpose of the bacteria?

A
  • Morphologically diverse.
  • Usually nonmotile.
  • Ferment sugars for energy.
15
Q

Bacteroides fragilis does what? What does it cause?

A
  • Disruption of tissue barriers and the spread of intestinal flora into adjacent tissue causes polymicrobial infection
  • Why b. fragilis is seldom the solitary organism of infection
16
Q

Bacteroides species cause what to be released? What does this cause?

A

Bacteroides species cause the release of significant levels of bradykinin in human plasma, a mechanism that will provide the bacteria with an opportunity to spread by inhibition of clot formation

17
Q

LACTOBACILLUS:
* What is the morphology?
* Consititute a significant component of what?
* What does it form?
* Among the most common of?

A
  • Gram positive, anaerobic, rod-shape, non spore forming
  • Lactobacillus species constitute a significant component of the human microbiota in the digestive system and female genital system
  • Form a biofilm which allows them to survive in harsh environments
  • Among the most common probiotic (L. acidophilus) found in food such as yogurt
18
Q

AFB-Mycobacterium
* What is AFB?

A

acid-fast bacillus – type of bacteria that causes tuberculosis

19
Q

AFB - MYCOBACTERIUM

  • AFB tests are looking for what?
  • What is AFB smear and culture?
A

AFB tests are looking for the presence of AFB bacteria in your sputum
* AFB smear – provide results in 1-2 days , but only shows a possible or likely infection, but no definitive diagnosis
* AFB culture – provides results in 6-8 weeks, can positively confirm a diagnosis of TB or other infection

20
Q

Mycobacterium:
* Morphology?
* What is their cells well components?
* How many species?
* Found where?
* Fast or slow on culture media?

A
  • Gram positive, aerobic, acid fast rods that sometimes branch and form filaments
  • Have mycolic acid as component of their cell walls
    - Cells walls are very hydrophobic, impenetrable by antibiotics
  • More than 100 species
  • Found in soil and water
  • Slow growing on culture media
21
Q

M.tuberculosis:
* What is it considered?
* Associated with what? What is this due to?

A
  • One of the most common human infectious diseases,
    causing 3 million deaths a year worldwide
  • Associated with impoverished conditions,TB is on the rise in industrialized nations
  • Due to immigration, emergence of drug-resistant strains, and AIDS
22
Q

What is the difference between latent TB and Active TB?

A
23
Q
  • What does M.laprae cause?
  • What is seen in immunocompromised patients?
A

M.laprae
* Leprosy

M. avium complex(MAC)
* Seen in immunocompromised patients

24
Q

What are the gram negative bacili we need to know?

A
  • E-coli
  • Klebsiella
  • Salmonella
  • Shigella
  • Yersinia

KESSY

25
Q

E. Coli:
* What is the morphology?
* Live where but what can they cause?
* How can you contract e-coli?

A
  • Gram negative, anaerobe, non spore forming, rod shaped
  • Large and diverse group of bacteria, most are harmless and live in the intestines and help you digest the food you eat, but others can cause diarrhea, UTI, respiratory illness and pneumonia
  • Can contract E-coli by eating foods containing the bacteria
26
Q

There are 6 strains of E. coli are known to cause diarrhea, name two of them

A
  • Shiga toxin-producing E-coli- most common for food contamination. Produces a toxin (Shiga) that damages the lining of your small intestines and causes diarrhea
  • Enterotoxigenic E. coli – this strain is commonly known to cause travelers diarrhea
27
Q

Klebsiella:
* What is the morphology?
* What is prominent and what does it account for?
* Found where?
* The majority of human klebsiella infections are caused by what?

A
  • Gram negative, rod-shaped, aerobic, non motile,
    with a prominent polysaccharide capsule
  • The capsule encases the entire cell surface and
    accounts for the large appearance of the organism
  • Found in the human intestines and in human stool, they are an opportunistic pathogen
  • Significant cause of healthcare associated infections
  • The majority of human klebsiella infections are caused:
    * K. pneumoniae
    * K. aerogenes
28
Q

KLEBSIELLA PNEUMONIAE:
* Associated with that?
* Typically colonizes where?
* Once the bacterium enters the body, it can display what?
* What is produced and what is that called?
* What does it cause?

A
29
Q

Salmonella:
* What is the morphology?
* Common cause of what?
* How do you get it? What does it cause?

A
  • Gram negative, flagellated, facultatively anaerobic bacilli
  • Common cause of self limited food poisoning, Est 2 million Americans each year
  • Infected food survives passage through the gastric acid barrier and invades the mucosa of the small and large intestines and produces toxins. The acute inflammation causes diarrhea
30
Q

Shigella:
* What is the morphology?
* Causes what?
* Is a threat to who?
* Pathogenic mechanism?
* Similar to what? What makes it different?

A
  • Gram negative, non motile, anaerobic, non spore forming rods
  • Causes dysentery
  • Is a threat to travelers from developed countries when visiting in endemic areas, and sporadic food or water borne outbreaks
  • Pathogenic mechanism of shigella is complex- invasion of shigella into the colonic epithelium, causing colitis and ulceration
  • Similar to e.coli, but pathogenicity/virulence phenotype is a distinguishing feature
31
Q

Yersenia:
* What is the morphology?
* Causes what?
* Humans acquire Yersinia after what?
* What is the key feature of the disease?

A
  • Gram negative bacillus shaped bacterium that causes zoonotic disease called yersinosis
  • Causes acute diarrhea, mesenteric adenitis, terminal ileitis
  • Humans acquire Yersinia after consumption of contaminated food (raw or uncooked pork products) or a blood transfusion
  • Key feature of the disease is that the person sheds the organism in feces for nearly 3 months after symptoms have subsided-> Detection in stool
32
Q

Helicobacter pylori:
* Morphology?
* Often found where and when?

A
  • Gram negative, spiral shaped, microaerophilic bacterium that affects up to 50% of the population worldwide
  • Often found in the stomach of affected individuals, usually acquired in early childhood and persists in the
    absence of treatment
33
Q

Helicobacter pylori:
* For formation of clinical disease, what are the 4 important components?

A
  1. urease activity plays an important role in countering the acidic environment of the stomach
  2. Flagella-mediated motility helps the bacterium move towards the host gastric epithelial cells
  3. Bacterial adhesins interacting with the host cell receptors – leads to successful colonization
  4. Effector proteins/toxins are released and lead to host tissue damage
34
Q

HELICOBACTER PYLORI

  • Both acute and chronic inflammation is seen in H. pylori gastritis as what?
  • What does the gastric epithelial layer secrete? what does this cause?
  • What stain do you use?
A
  • Both acute and chronic inflammation is seen in H. pylori gastritis as eosinophils, neutrophils, mast cells, and dendritic cells are stimulated.[9] The gastric epithelial layer also secretes chemokines to initiate innate immunity and activates neutrophils that further damages the host tissue leading to the formation of gastritis and ulcer
  • Utilize Hematoxylin and eosin staining (H&E) – can visualize the bacteria with a sensitivity and specificity up to 90
35
Q

Vibrio:
* What is the morphology?
* Resident of what?
* V.Vulnificus takes up residence where?
* The bacilli then infect human hosts by what? What can this result in?

A
36
Q
A
37
Q

Haemophilus:
* What is the morphology?
* Colonizes where?
* Prior to vaccination, H. influenzae was the most common cause of what?
* Haemophilus influenzae can cause what?
* Nontypable H influenzae can cause what?

A
  • Gram negative coccobacilli (very short rods)
  • Colonizes the nasopharynx
  • Prior to vaccination, H. influenzae was the most common cause of meningitis in children between ages 6months-2 years
  • Haemophilus influenzae can cause meningitis, epiglottitis, bacteremia, and cellulitis.
  • Nontypable H influenzae can cause otitis media, sinusitis, tracheobronchitis, and pneumonia
38
Q

What is this?

A

Haemophilus

Medical Sciences (11 decks)

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