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medical microbiology test 2 > lecture 8 > Flashcards

lecture 8 Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

strict pathogens are organisms always associated with human disease and include

A

 Mycobacterium tuberculosis (tuberculosis)
 Neisseria gonorrhoeae (gonorrhea)
 Plasmodium spp. (malaria)
 Rabies virus

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2
Q

Opportunist pathogen

A

Do not produce disease in their normal setting but establish disease when they are introduced into unprotected sites such as blood, and tissues

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3
Q

Examples of opportunistic pathogen

A
  • Staphylococcus aureus
  • E. coli
  • Candida albicans
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4
Q

How do opportunistic pathogens take advantage of pre-existing conditions to grow and cause disease

A
  • Immunosuppression; If a patient’s immune system is defective, that patient is more susceptible to disease caused by opportunist pathogens.
  • Burn victims and the lungs of patients with cystic fibrosis are at higher risk to Pseudomonas aeruginosa infections
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5
Q

Colonization

A

These organism do not interfere with normal body functions rather they colonize the host for hours, days or permanently

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6
Q

Colonization resistance

A

The normal microbial flora try to crowd out the bad microbes

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7
Q

Disease

A

Occurs when the interaction between microbes and humans lead to a pathologic process characterized by damage to the host.
Results from the damage or loss of tissue or organ function due to infection or host inflammatory responses.

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8
Q

Virulence

A

measure of how pathogenic a bacterium is.

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9
Q

Pathogenicity

A

Refers to the capacity of a microbe to produce disease

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10
Q

Virulence factor or determinant

A

Gene products that allow a microorganism to establish itself within or on a host and enhance the potential to cause disease.

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11
Q

Clinical infection

A

Disease

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12
Q

Subclinical infection

A

carrier state

latent infection

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13
Q

Functions of Normal Flora

A
  • protects against pathogens
  • recycles host material
  • Detoxifies material
  • Produce vitamins and other growth factors
  • Aids in Digestion
  • Potential reservoir of infection
  • Contaminates in clinical sample
  • Stimulates development of immune system
  • Gnotobiotic animal
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14
Q

Lamina propria in GI tract

A

Development of immune system

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15
Q

Control of Normal flora

A
  • Environmental considerations in different regions
  • Diet, gender, environmental exposure
  • non specific host defense mechanisms
  • Host immune system
  • Competition and interactions with other organisms
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16
Q

Environment of Skin and hair

A

 Dry to moist
 Salts and fatty acids present
 Aerobic with anaerobic microenvironments
 Gram positive organisms are the most common found on the skin surface.

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17
Q

Normal flora of skin and hair

A
  • S. aureus
  • S. epidermidis
  • Micrococcus
  • P. acnes
  • Diptheroids
  • Yeasts
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18
Q

Environment of Conjunctivae

A

 Moist
 Lysozyme present
 Mechanical action of eyelids

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19
Q

Conjunctivae flora includes”

A
  • S. epidermis

* Diptheroids

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20
Q

Environment of Nasopharyngeal region

A

 Dry to moist
 Hairs for filtering
 Mucus traps organisms

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21
Q

Flora of Nasopharyngeal region

A
  • S. aureus
  • S. epidermis
  • Streptococcus sp.
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22
Q

Environment of Mouth

A 
	Moist
	Aerobic to anaerobic 
	Mechanical chewing
	Saliva 
	Mucus
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23
Q

Flora of mouth

A
  • Large variety
  • Streptococcus sp
  • Bacteroides
  • Veillonella
  • Porphyromonas
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24
Q

Stomach and small intestines environment

A

 Stomach pH thus the organisms present are the small number of acid-tolerant bacteria.
 Organisms live in mucus
 Intestines buffered by bicarbonate
 Presence of bile salts and digestive enzymes
 Mucus and epithelial turnover
 Anaerobic
 Unlike in the stomach the small intestines is colonized by many different organisms

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25
Q

If the stomach is obstructed…

A

such as abdominal surgery, then a condition called blind loop syndrome can occur

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26
Q

Flora of stomach and small intestines include:

A
  • H. pylori
  • Lactobacillus,
  • Streptococcus
  • Enterococcus
  • Yeasts
  • Veillonella
  • Enterobacteriaceae
27
Q

environment of the colon

A

 Anaerobic
 Similar to small intestines
 Higher populations

28
Q

Flora of colon includes

A

• Similar to small intestines with more diversity and numbers of organisms

29
Q

The Genitourinary tract is…

A

The Urinary system

  • Anterior urethra
  • bladder
  • Vagina
  • cervix
30
Q

Voiding of urine and uroepithelial cells does what?

A

clear out any colonizing bacteria in the bladder that should migrate upstream from the urethra, keeping the bladder sterile unless disease is present.

31
Q

Environment of Genitourinary tract

A 
	GAG layer 
	Epithelial turnover 
	Native flora in distal regions 
	sigA
	mucosa
32
Q

Genitourinary tract flora and its changes through life

A

Large variety of organisms at distal end including Lactobacillus sp.
• Present in urethra
• Also present in females at birth and predominate for ~ 6 months then after the levels of maternal estrogen has declined the vaginal flora changes to include more bacteria as well. Then at puberty, the microbial flora again changes to where Lactobacilli reemerges as predominant organism.

33
Q

In the Urethra fecal organisms such as Enterococcus, Enterobacteriaceae and candida can do what?

A

Invade the urinary tract, multiply in urine and lead to significant disease.

34
Q

Other organisms in the Genitourinary tract like N. gonorrhea and C. trachomatis are common causes of what?

A

urethritis and can persist as asymptomatic colonizers of the urethra.

35
Q

Environment of Circulatory system

A
  • Flow

- Constant exposure to immune system

36
Q

Flora of the circulatory system includes:

A

-Naturally sterile

except for brief periods of transient bacteremia.

37
Q

Nervous system environment

A
  • Histiocytes
  • Tissue barrier against pathogen entry
  • infections of CNS are always serious
38
Q

Normal flora of Nervous system

A

non; sterile

39
Q

Human Microbiome project (HMB)

A

 Initiate to characterize comprehensively the human microbiota and analyze its role in human health and disease. Tests how changes in the human microbiome are associated with human health or disease.
 5 year project launched in 2008 with a total budget of $115 million

40
Q

Microbial Forensics

A

 Forensic identification using skin bacterial communities
 Sequence based information to see if computer users could be identified on basis of skin flora left on computer keys.
 The UniFrac algorithm uses the degree of phylogenetic overlap between any pair of communities with points that are close together representing samples with similar bacterial communities.

41
Q

answering question What types of microbes are present?

A

 PCR amplification using primers that binds to 16S rRNA
 Sequence and look at DNA
 Limitations: Some species are missed, not quantitative.

42
Q

answering question What is the clonal relationship among different isolates of the same species

A

 Done using restriction enzyme profiling

 Limitations: Does not provide taxonomic identification of community members.

43
Q

answering question What are the physiological potential of members of microbial population?

A 
	Done using Metagenomic analysis 
	Isolates DNA, shear/digest into small fragments. Clone and sequence then use the data base for comparison 
	Strategy for metageonomics 
•	Sampling from habitat 
•	Filtering particles, typically by size
•	 DNA extraction and lysis
•	cloning and library 
•	 sequence the clones
•	sequence assembly.
	Limitations include: 
•	Major sequencing capacity is required 
•	Many are genes of unknown function 
•	Difficult to associate a particular gene with a particular microbe.
44
Q

What are the three forensic microbial methods

A
  • PCR amplification
  • restriction enzyme profiling
  • Metagenomic analysis
45
Q

Risk factors if Reservoirs of opportunistic infections (can cause disease under special circumstances)

A

 Alteration in numbers of normal flora
 Translocation of normal flora
 Weakened host defense due to trauma, stress or disease.
 Circumvention of host defenses (ex: catheterization)

46
Q

Gastric ulcers suspected to be caused by

A

H. pylori

47
Q

Gastric cancer in some cases is expected to be caused by

A

H. pylori

48
Q

Peridontal disease is suspected to be caused by

A

1) Porphymones gingivalis and (2) other agents

49
Q

Athersclerosis is suspected to be caused by

A

Chlamydophilia pneumoniae

50
Q

Low birth weight and preterm babies are suspected to be caused by

A

(1)Bacterial vaginosis and (2) Microbiota shifts

51
Q

Cerebral palsy is suspected to be caused by

A

placental infection

52
Q

Rheumatoid arthritis is suspected to be caused by

A

Intestinal anaerobic bacteria, B. burgdorferi (Lyme Disease)

53
Q

Crohn’s Disease is suspected to be caused by

A

Mycobacterium avium paratuberculosis or shift of intestinal bacterial population.

54
Q

C. difficile associated diarrhea has relapse rate of

A

20%

55
Q

C. difficile associated diarrhea often caused by

A

 Antibiotics such as Clindamycin wipes out normal flora and C. Difficile takes over
 The loss of controlling bacteria with broad spectrum antibiotic treatment often allows the outgrowth of C. difficile.

56
Q

C. difficile associated diarrhea often treated with

A
  • Metronidazole and Vancomycin

- can also be treated by restoration of normal flora by fecal implant

57
Q

Oxalobacter and kidney stones is related how?

A

CaoX stones formation in absence of O. formignes
• The absence of O. formigenes could lead to increased colonic absorption of oxalate, and the subsequent increase in urinary oxalate could favor the development of stones.

58
Q

Oxalobacter does what

A

a Gram-negative, anaerobic bacterium that metabolizes oxalate in the intestinal tract and is present in a large proportion of the normal adult population.

59
Q

Gut microbe that stops food allergies

A

 Clostridia keeps peanut allergies away
 Commensal bacteria protect against food allergen sensitization. Reintroduction of a Clostridia-containing microbiota to Antibiotic treated mice blocks sensitization to a food allergen.

60
Q

Clostridia colonization induces IL-22 in the intestinal lamina propria (LP) and does what

A

that this cytokine acts to reduce uptake of orally administered dietary antigen into the systemic circulation, contributing, in part, to protection against sensitization.

61
Q

A big nerve known as the vagus nerve, which runs all the way from …

A

the brain to the abdomen

62
Q

Why was the vagus nerve suspected of being responsible for the gut feeling

A

 When researchers in Ireland cut the vagus nerve in mice, they no longer saw the brain respond to changes in the gut. The presence of certain bacteria can produce signals altering the brain and behavior.

63
Q

Antibiotic in healthy people

A

 Healthy people’s normal flora seems to recover quite well when treated with a mild course of antibiotics

64
Q

Antibiotics in sick people

A

 However in sick and weakened people a side effect of antibiotics can be infected with a germ called C. difficile (clostridium difficile) which cause hundreds of thousands of deaths worldwide.
 One solution to destruction of normal flora by antibiotics is probiotics

medical microbiology test 2 (2 decks)

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