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Pathogens > Bacteria > Flashcards

Bacteria Flashcards

1
Q

How is DNA stored in bacteria?

A

Bacteria have no nucleus but instead have a single circular hoop of chromosomal DNA and may also have a plasmid in addition to this.

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2
Q

How do bacteria reproduce?

A

By binary fission

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3
Q

What are the differences between a gram positive and gram negative bacteria?

A

Gram positive - thick peotidoglycan cell wall, highly polar cell wall

Gram negative - thin peptidoglycan cell wall, additional outer membrane surround

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4
Q

Pathogenic bacteria are heterotrophic. What does this mean?

A

They derive all of their nutritional requirements from complex organic substances

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5
Q

What is the name of the tightly coiled region of DNA in bacteria?

A

Nucleoid

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6
Q

The genome of a bacteria only consists of exons. T/F?

A

True - bacteria have no introns

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7
Q

Bacteria have a cytoskeleton. T/F?

A

False

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8
Q

Where in the bacteria would ‘extra’ genes be stored?

A

Plasmids

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9
Q

What advantage do R-plasmids provide bacteria with?

A

Antibiotic resistance

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10
Q

Many of the functions which are performed by membrane-bound organelles in eukoryotes are carried out by what structure in bacteria?

A

Cell membrane

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11
Q

Bacterial cells contain no organelles in their cytoplasm other than…?

A

Ribosomes

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12
Q

What proteins compose the flagellum of bacteria?

A

Flagellins

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13
Q

Give an example of a bacteria which can be classified as ‘gram stain unreliable’.

A

M.tuberculosis

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14
Q

What colour will gram negative and gram positive bacteria appear under the gram stain.?

A

Gram positive - purple

Gram negative - pink

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15
Q

Name an alternative method of staining which can be used for gram stain unreliable bacteria?

A

Ziehl-neelson method

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16
Q

What are the two types of pilli in bacteria amd what are their functions?

A

Common pilli - responsible for attachment and adhesion

Sex pilli - associated with conjugation where genes are transferred between bacteria

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17
Q

Some bacteria have capsules. What are the function of these capsules?

A

To protect the bacteria from phagocytosis

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18
Q

What is the outer membrane of gram negative bacteria anchored to?

A

It is anchored to lipoprotein molecules in the peptidoglycan layer.

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19
Q

What are the main constituents of the outer membrane of gram negative bacteria?

A

Lipopolysaccharides

Lipoprotein

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20
Q

How do hydrophilic molecules enter a gram-negative bacteria?

A

Through channels or pores from from proteins called porins

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21
Q

What is the name of the gel like layer which exists between the two membranes kf gram negative bacteria?

A

Periplasm

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22
Q

What are the three main shapes of bacteria?

A

Cocci (spherical)
Bacillus (rod shaped)
Spirilla (helical)

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23
Q

What is the shape of a bacteria determined by?

A

Its cell wall

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24
Q

Give two examples of gram positive cocci.

A

Staphylococcus aureus

Streptococcus pneumoniae

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25
Q

Give two examples of gram negative cocci.

A

Neisseria meningiditis

Neisseria gonorrhoeae

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26
Q

Give two example of gram positive bacilli

A

Listeria monocytogenes

Corynebacterium diptheriae

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27
Q

Give two examples of gram negative bacilli.

A

Escherichia coli

Salmonella species

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28
Q

What is the name of coccus bacteria which divide in two planes?

A

Tetrad

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29
Q

Which cocci bacteria can result from division in one plane?

A

Diplococcus (bacteria arranged in pairs)

Streptococcus (bacteria arranged in chains)

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30
Q

Coccus which divide in three planes produce…?

A

Sarcina arrangement

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31
Q

How is a staphylococcus arrangement produced?

A

By the division of a coccus bacteria in random planes

32
Q

Bacilli all divide in one plane only. What is the difference between a bacillus, streptobaccilus and coccobacillus?

A

Bacillus - bacteria exists singularly
Streptobacillus - bacilli arranged in chains
Coccobacillus - bacilli exist singularly in oval shapes which resemble cocci

33
Q

What are the three forms of spiral bacteria?

A

Vibrio - comma shaped rod
Spirillum - thick rigid spiral
Spirochete - thin flexible spiral

34
Q

What is the minimum inhibitory concentration?

A

The minimum concentration of an antibacterial agent required to inhibit visible growth of a bacteria

35
Q

What is the minimum bactericidal concentration?

A

The minimum concentration of an antibacterial agent required to kill a bacterium.

36
Q

What is the name for bacteria which are capable of growing and reproducing at cold temperatures?

A

Psychrophilic bacteria

37
Q

Some bacteria can be describes as facultative anaerobes - what does this mean?

A

The bacteria normally undergoes aerobic respiration but can undergo anaerobic respiration when oxygen is not available.

38
Q

Thermophilic bacteria are bacteria that…?

A

Can grow and reproduce at high temperatures

39
Q

What are mesophilic bacteria?

A

Bacteria which can grow and reproduce at moderate temperatures

40
Q

What are spores?

A

Vegetative forms that some bacteria can become to enable viability under adverse conditions

41
Q

What do endospores consist of?

A

Nucleic acid, cytoplasm and a tough outer coat

42
Q

What are commensal organisms?

A

The natural flora which ordinarily live on our bodies

43
Q

When are natural flora acquired and what benefits do they provide?

A

They are acquired soon after birth and provide many benefits including inhibiting the establishment of infection by competition and natural by-products, producing vitamins in the gut as a metabolic end-product and stimulating the immune system.

44
Q

What are the sterile body sites?

A

These are body sites without commensal organism colonisation, including: blood, tissues, organ systems (other than colon and ,large intestine), CNS, lower respiratory tract, sinuses, inner and middle ear, renal system (down to posterior urethra, female reproductive tract (down to cervix) and the eye (other than the exposed conjunctivae).

45
Q

What is an opportunistic infection?

A

An infection that would not normally cause infection in a healthy human hist but can cause infection when the human host is immuno-compromised.

46
Q

What is a nosocomial infection?

A

An infection acquired in hospital

47
Q

What does the term ‘carrier state’ mean?

A

A host whose symptoms are no longer present but still ‘carries’ the microorganism in a dormant state

48
Q

What is the concept of the infectious dose?

A

This is the concept that a host must be exposed to a certain number of a particular microorganism for an infection to be present.

49
Q

What are endotoxins?

A

Lipopolysaccharides in the outer membrane of gram-negative bacteria which can elicit a strong immune response from the hist and make the patient appear septic.

50
Q

What are exotoxins?

A

These are produced by gram-positive bacteria and are produced intracellular,y and then released during infection. These induce a non-specific immune stimulation.

51
Q

List some of the host and environmental factors which can influence infection.

A

Hist age, gender, ethnicity, personal hygiene and nutrition
Medical conditions, prescription drugs
Immunocompromise
Presence of foreign objects (infection with commensals more likely)
Vaccination history
Crowding, seasonal variations, sanitation

52
Q

List some microbiological emergencies.

A

Infection of a normally sterile site
Meningitis/CNS infection/cerebral abscess
Septic arthritis
Deep ocular or periorbital infections
Infections involving a breach of the GI tract
Outbreak scenario or public health risk
Infection where the patient is septic

53
Q

What is sepsis?

A

A physiological response to severe infection involving cytokine cascades, free radical production and vasoactive mediators.
In severe sepsis there is organ hypoperfusion (inadequate blood supply),.
In septic shock there is hypotension (low blood pressure) despite resuscitation

54
Q

What is a vector?

A

An organism which carried a disease or parasite from one organism to another.

55
Q

What is a formite?

A

An object in the environment which is contaminated.

56
Q

What is disinfection as opposed to sterilisation?

A

Disinfection - removal of most but not all viable microorganisms to safe levels
Sterilisation - killing or removing all microorganisms including transmissible agents

57
Q

Where does replication of the bacterial genome begin?

A

The origin of replication

58
Q

What are the four phases of bacterial growth and replication?

A

Lag phase
Log phase
Stationary phase
Death phase

59
Q

What is the meaning of the term generation time?

A

The time it takes for the bacteria population to double

60
Q

What is. Transposition?

A

The movement off transposons between bacterial plasmids or between plasmid. And chromosome

61
Q

How do bacteria reproduce?

A

Asexually by binary fission

62
Q

Why does bacterial growth change from the log phase to the stationary phase?

A

Due too the depletion of nutrients and build up of toxic waste products

63
Q

What is a parasite?

A

An organism which gains benefit from the host at the expense of the host

64
Q

What are the benefits which commensal organisms provide?

A

Competition and natural by products of commensal organisms inhibit the establishment of infection
Vitamins in the gut produce metabolic end products
Immune stimulation

65
Q

What are some of the commensal organisms which reside in the nose?

A

Staphylococcus aureus
Staphylococcus epidermidis
Cornyebactrium species

66
Q

What are some of the commensal organisms which reside in the mouth?

A

Streptococcus species
Fusobactrium species
Actinomyces species

67
Q

What are some of the commensal bacteria which reside on the skin?

A

Staphylococcus epidermidis
Propionibacterium acnes
Pityrosporum ovale

68
Q

What are some of the commensal organisms in the throat?

A

Streptococcus species
Corynebacterium species
Neisseria species
Mycoplasma species

69
Q

What are some of the commensal organisms in the large intestine?

A 
Escherichia coli
Lactobaccilus sledies
Streptococcus species
Clostridium species
Candida albicans
70
Q

Where in the body do the majority of commensal organisms reside?

A

Large intestine

71
Q

What are some of the common bacteria to infect the respiratory system?

A

Streptococcus pneumoniae
Streptococcus pyogenes
Haemophillus influenza

72
Q

What are some of the common bacteria to infect the gastrointestinal system?

A

Camplyobacter

Salmonella

73
Q

What are some of the common bacteria to infect the musculoskeletal system?

A

Staphylococcus aureus

74
Q

What are some of the common bacteria to infect the central nervous system system?

A

Neisseria meningiditis
Streptococcus pneumoniae
Haemophilus influenzae

75
Q

What are some of the common bacteria to infect the renal system?

A

E.coli

Pathogens (3 decks)

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