Lecture 12: Normal Microbiota and the Host Flashcards Preview

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Flashcards in Lecture 12: Normal Microbiota and the Host Deck (47):
1

Normal Microbiota _____ colonize the host

permanently 

2

Transient microbiota may present in host for 

days, weeks, or months

3

The relationship between nomral microbiota and the host

symbiosis 

4

An association of two or more different species of organisms 

symbiosis

5

Physical contact between dissimilar organisms

Symbiont

6

What is commensalism

An association between two organisms in which one benefits and the other is unaffected

7

What is mutualism

both organisms benefit

8

What is parasitism

One organism benefits at the expense of the other 

9

Microbial antagonism is a ____ between microbes

competition 

10

Normal microbiota protect the host by: 

  • Occupying niches that pathogens might occupy
  • Producing acids
  • Producing bacteriocins

11

What is a Microbiome

  • All the genes of the host and the microbiota

12

Superorganisms

  • Emerge when the gene-encoded metabolic processes of the host become integrated with those of the microbe 
  • a blend of host and microbial traits where host and microbial cells cometabolize various substrates, resulting in unique products 

13

Germfree animals can be used 

  • can be used to study effects of microbes on animal health by
    • comparing gerfree animals to normal animals
    • introducing a single microbe to the germfree animal and observing effects
  • Can be coupled with genomic studies for maximum benefits

14

What are Germfree animals produced

  • Cesarean section, raised in sterility 

15

What is the Human Microbiome Project

  • Attempt to define 'normal' populations of microbes in and on human beings

16

as of 2012 the human microbiome project had genome reference collection for ___ microorganisms (out of an anticipated 900) obtained 

178

17

What are the reasons to study Normal Human Microbiota

  • To gain insight into possible infections resulting from injury 
  • To understand causes and consequences of overgrowth of microbes normally absent from a body site
  • To increase awareness of role played by indigenous microbe in stimulating immune responses 

18

Bifidobacteria is found in 

  • breast fed babies 

19

What is Protrophic

  • can synthesize all amino acids and growth factors from simple carbohydrates 

20

Normal microbiota protect the host by 

  • competing with pathogens or altering the environment
    • occupying niches that pathogens might occupy
    • Producing acids
    • Producing bacteriocins

21

Probiotics 

  • Live microbes applied to or ingested into the body, intended to exert a beneficial effect 

22

Members of normal microbiota that produce disease under certain circumstances

Opportunistic pathogens 

 

23

Debiliated host with lowered resistance to infection 

Compromised host 

24

Normal Microbiota of the skin

  • Mechanically strong barrier
  • Inhospitable environment
    • slightly acidic pH 
    • high concentration of NaCl
    • many areas low in moisture
  • Inhibitory substances (e.g., lysozyme)
  • mostly Gram-positive, salt tolerant bacteria
    • Staphylococci  (ex. S. epidermis)
    • Micrococci (ex. M. luteus)
    • Diphtheroids
      • Aerobes on surface 
        • Corynebacterium xerosis
      • Anaerobes in hair follicles 
        • Propionibacterium acnes
  • a few gram-negative organisms (ex. Acinetobacter) 
  • grow on oils 
    • yeast
      • ex. Malassezia furfur 

25

Anaerobes in hair follicles 

Propionibacterium acnes 

26

is the bacteria on the skin gram positive or gram negative 

mostly gram positive with a few gram-negative organisms (ex. Acinetobacter) 

27

Acne Vulgaris 

  • Caused in part by activities of Propionibacterium acnes
  • Sebum
    • fluid secreted by oil glands
    • accumulates, providing hospitable environment for P. acnes
  • Comedo
    • plug of sebum and keratin in duct of oil gland
    • results from inflammatory response to sebum accumulation 

28

29

Normal Microbiota of the eye 

  • From birth throughout a human life, small numbers of bacterial commensals are found on the conjunctiva of the eye
  • The predominant bacterium is Staphylococcus epidermis 

30

Normal microbiota of the external ear 

similar to skin flora as well as fungi 

31

Normal Microbiota are responsible for dental caries examples: 

  • S. mutans
  • Lactobacillus

32

Normal Microbiota of the Mouth

  • Contains organisms that survive mechanical removal by adhering to gums and teeth
    • Contribute to formation of dental plaque, dental caries, gingivitis, and periodontal disease 
  • Within hours of birth, the oral cavity is colonized by microorganisms from the surrounding environment 
  • Oral bacteria are responsible for dental caries (ex. S. mutans and Lactobacillus)
  • Suppress pathogens by competitive inhibition in upper respiratory system 

33

What two bacteria are found inside the nostrils 

  • Staphylococcus aureus
  • S. epidermis

34

The Pharynx and trachea contina Gram____ bacteria: 

  • gram positive bacteria
  • Staphylococci (ex. S. epidermis)
  • Micrococci (ex. M. luteus)
  • Diphtheroids
  • Streptococci (both alpha and beta-hemolytic

35

Nasopharynx may contian low numbers of potentially pathogenic microbes such as 

  • Streptococcus pneumoniae
  • Neisseria meningitidis 
  • haemophilus influenza
  • Mycoplasmas

36

Does the lower respiratory tract have a normal microbiota 

  • No 
  • Microbes moved by: 
    • Continuous stream of mucous generated by ciliated epithelial cells
      • cilliary escalator
    • Phagocytic action of alveolar macrophages
    • lysozyme in mucus 

37

Most microbes of the stomach are 

  • killed by acidic conditions 
    • some survive if pass through stomach very quickly 
    • Some can survive if ingested in food particles

38

Which part of the small intestine has the most microbes

  • The ileum 
    • flora present becoming similar to that in colon
    • pH becomes more alkaline 

 

39

What has the largest microbial population in the body

The large intestine (colon)

40

The microbial population of the large intestine (Colon) is eliminated from body by _____ but replaced rapidly by 

  • peristalsis, desquamation, and movement of mucus 
  • High reproductive rate

41

most of the microbes in the large intestine (colon) are 

anaerobes 

42

Microbes in the large intestine (colon)

  • E.coli
  • Bacteroides
  • Fusobacterium
  • Lactobacillus
  • Enterococcus
  • Bifidobacterium
  • Enterobacter
  • Citrobacter
  • Proteus 
  • Klebsiella
  • Candida (fungus)

43

What parts of the genitourinary tract is normally free of microbes

Kidneys, ureter, and bladder

44

Why is the female genital tract's microbiota in a complex state of flux due to ______ with ______ predominating 

  • menstrual cycle 
  • Acid-tolerant lactobacilli

45

_______ microbiota are predominant in the vagina

  • Lactobacilli 
    • produce H2O2
    • Grow on glycogen secretions 

 

46

Urinary infection is indicated by

  • > 10,000 bacteria/mL
  • 100 coliforms/mL
  • Positive urine leukocyte esterase (LE) test

47

The "extinction" of H. pylori is linked to several immune and metabolic disorders such as 

Asthma, allergies, celiac disease, even acid reflux disease