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Gabe's Locomotor > Opportunistic Infections > Flashcards

Opportunistic Infections Flashcards

1
Q

When does a bacterium not need to be as virulent to cause infection?

A

When host resistance is reduced

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2
Q

What are the frequently encountered opportunistic pathogens?

A

E. coli

Staph. aureus

Klebsiella pneumoniae

Enterococcus spp.

Pseudomonas aeruginosa

Enterobacter spp.

Serratia spp.

Proteus spp.

Clostridium difficile

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3
Q

What kind of epidemic can many of the opportunistic pathogens cause?

A

Nosocomial epidemics

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4
Q

Which of the opportunistic pathogens can’t cause nosocomial epidemics?

A

E. coli

Proteus spp.

Clostridium difficile

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5
Q

What do opportunistic infections in a patient often indicate?

A

That there is something else wrong with the patient because the host must be altered in some way for pathogens to take hold.

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6
Q

Which local defects in a patient can lead to opportunistic infections?

A

Anatomical defects

Surgical and other wounds

Burns

Catheterisation

Foreign bodies in general

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7
Q

Why does a foreign body in the patient often lead to opportunistic infections?

A

Because the pathogen can find refuge in the foreign body

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8
Q

What type of anatomical defects can lead to opportunistic infections?

A

Short urethra in women can lead to UTIs

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9
Q

How can surgery lead to an opportunistic infection?

A

Breaking of the skin means it is more likely to become infected.

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10
Q

Which systemic defects in a patient can lead to opportunistic infections?

A

Extremes of age

Leukopaenia

Malignancy

Malnutrition

Diabetes

Liver disease

Immunocompromising infections

Antimicrobial treatment

Immunodeficiencies

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11
Q

What is candadiasis one of the first indications of?

A

Diabetes

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12
Q

Which infections can lead to an increased likelihood of opportunistic infections?

A

HIV

Measles

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13
Q

What are the different types of opportunistic infection?

A

Wound infection

UTI

Intra-abdominal infection

Septicemia (sepsis)

Meningitis

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14
Q

Which group of people are particularly susceptible to meningitis?

A

Neonates

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15
Q

What are the two sources of opportunistic infections?

A

Endogenous (own microbiota) and exogenous

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16
Q

What are the different types of specimens that can be cultured?

A

Wound swab

Pus

Urine

Sputum

Blood

CSF

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17
Q

What does treatment of opportunistic infections depend on?

A

Antibiotic susceptibility

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18
Q

True or false: nosocomial strains are often multi-resistant.

A

True

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19
Q

What is used to treat multi-resistant nosocomial strains of opportunistic pathogens?

A

More potent bactericidal agents

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20
Q

What are the 2 ways of preventing opportunistic nosomial pathogens?

A

Aseptic technique (esp. hand hygiene)

Education

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21
Q

Is pseudomonas G- or G+?

A

Gram negative

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22
Q

What morphology is pseudomonas?

A

Rod

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23
Q

Is pseudomonas motile?

A

Yes

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24
Q

What is pseudomonas’ relationship with oxygen?

A

It’s an aerobe or facultative anaerobe

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25
Q

Is pseudomonas fermenting or non-fermenting?

A

Non-fermenting

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26
Q

Is pseudomonas sporing or non-sporing?

A

Non-sporing

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27
Q

What would the results for catalase and oxidase be for pseudomonas?

A

Catalase and oxidase positive

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28
Q

What do some species of pseudomonas, e.g. pseud. aeruginosa, produce?

A

Pigments - e.g. pyocyanin in ps. aeruginosa.

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29
Q

Why can pseudomonas survive almost anywhere?

A

Because it has low nutritional requirements

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30
Q

How is pseudomonas divided into species?

A

According to biochemical tests

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31
Q

What is pseudomonas aeruginosa subtyped according to?

A

Serotype and biotype

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32
Q

How is pseudomonas aeruginosa subtyped in epidemiological studies?

A

Using RFLP or MLST (multilocus sequence typing)

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33
Q

In which patients is ps. aerugonisa an important opportunistic pathogen?

A

Patients with cystic fibrosis

34
Q

Which species of pseudomonas is a ubiquitous saprophyte?

A

Pseudomonas aeruginosa

35
Q

What are the 4 species of of pseudomonas that colonise the respiratory tract of patients with cystic fibrosis?

A

Ps. aeruginosa

Burkholderia cepacia

Stenotrophomonas maltophilia

Burkholderia pseudomallei

36
Q

Which species of genera of Burkholdia causes melioidosis?

A

Burkholderia pseudomallei

37
Q

What type of environments is ps. aeruginosa particularly found in?

A

Moist environments

38
Q

What does ps. aeruginosa transiently colonise?

A

Skin

Mucous membranes

GIT

39
Q

Which diseases is ps. aeruginosa mostly associated with as a nosocomial pathogen?

A

Pneumonia

UTI

Sepsis

40
Q

Where are most ps. aeruginosa infections acquired from?

A

Environment

41
Q

How are ps. aeruginosa inspections spread in hospitals?

A

On hands and fomites

42
Q

What are all pseudomonas strains inherently resistant to?

A

Many antibiotics and weak disinfectants

43
Q

Which 2 areas can ps. aeruginosa cause superficial infections?

A

Skin and eye

44
Q

Which superficial infections of the skin can ps. aeruginosa cause?

A

Wound infection

Otitis externa

Folliculitis

45
Q

Which superficial infections of the eye can ps. aeruginosa cause?

A

Keratitis

Corneal ulcer

46
Q

Which two types of deep and systemic infections can ps. aeruginosa cause?

A

Pulmonary

Other

47
Q

Which pulmonary deep infections can ps. aeruginosa cause?

A

Nosocomial pneuomina

Chronic infections in patients with cystic fibrosis

48
Q

Which other deep and systemic infections can ps. aeruginosa cause?

A

UTI

Endocarditis

Osteomyelitis

Septicaemia

In immunocompromised patients

49
Q

When will ps. aeruginosa invade the skin?

A

When in very high numbers

50
Q

What does ps. aeruginosa adhere to weakly?

A

Intact epithelium

51
Q

What does ps. aeruginosa use to adhere to the intact epithelium?

A

Flagella
Pili
LPS

52
Q

What components of ps. aeruginosa bind to toll-like receptors?

A

LPS and flagellin

53
Q

What effect does binding to toll-like receptors have?

A

Cytokine production

54
Q

What does the LPS core of ps. aeruginosa bind to?

A

CFTR

CF transmembrane conductance region

55
Q

What does ps. aeruginosa do once it has adhered?

A

Produces a biofilm

56
Q

What assists adherence and biofilm formation?

A

Capsule

57
Q

What are the properties of ps. aeruginosa biofilms that are different to individual ps. aeruginosa?

A

More capsule material - mucoid phenotype

More adherent

Less invasive

Shorter LPS (no O-antigen)

Slowed growth

Increased resistance to antibiotics

58
Q

What is the advantage of the ps. aeruginosa biofilm?

A

Increased resistance to antibiotics

59
Q

What are many of the biofilm properties of ps. aeruginosa due to?

A

Activation of genes that are regulated by quorum sensing

60
Q

What is quorum sensing?

A

Regulatory cell process of signalling between bacteria that ensures there is sufficient cell density before a gene product is made, allowing bacteria to increase in numbers before secreting a product, e.g. virulence protein.

61
Q

What facilitates ps. aeruginosa’s spread through body tissues?

A

Reduced PMNs

Flagella

Exoenzymes

Exotoxins

LPS-CFTR-mediated invasion

62
Q

Which exoenzymes does ps. aeruginosa use to spread through body tissues?

A

Proteases

Haemolysins

Phospholipases

Elastase

63
Q

Which exotoxins does ps. aeruginosa use to spread through body tissues?

A

Exotoxin A

Exoenzymes S and U

These inhibit phagocytosis

64
Q

What effect does LPS-CFTR-mediated invasion by ps. aeruginosa have?

A

Aggravates corneal damage

65
Q

What happens in patients with a defect in CFTR?

A

Abnormal ion transport
Thickened mucus
Impaired mucociliary function

66
Q

Are pseudomonas and staph. inhibited by high salt concentrations?

A

No

67
Q

What do bacteria in biofilms resist?

A

Mechanical removal

68
Q

Are bacteria in biofilms more or less visible to the innate immune system?

A

Less

69
Q

What happens when DNA is secreted from the bacteria and dying cells in a biofilm?

A

Leads to thickened mucous

70
Q

Which bacterial variants will persist?

A

Those with reduced virulence

71
Q

What effect do the type III secreted proteins from ps. aeruginosa have?

A

Exoenzymes S, T, U and Y (=ExoS, ExoT, ExoU, ExoY) act on host cell targets to interfere with phagocytosis and enhance cytokine production

72
Q

What does exotoxin A released from ps. aeruginosa do?

A

Blocks protein synthesis (same as diphtheria toxin)

73
Q

What do LasA and LasB proteases released from ps. aeruginosa do?

A

Act together as elastase

74
Q

What do phospholipases released from ps. aeruginosa do?

A

Damages cell membranes

Degrades surfactant

75
Q

Can pseudomonas be eradicated from the environment?

A

No

76
Q

How can ps. aeruginosa be controlled?

A

Reduce risk of susceptible patients by suitable management of burns, neutropenia, catheters, ventilators

Be on alert for infection and treat early

Practice high levels of hand hygiene

Use contact lenses and solutions appropriately

Lifelong monitoring and treatment of CF patients

77
Q

What allows ps. aeruginosa to occupy many different environments?

A

Its low nutritional requirements and genetic versatility

78
Q

What is the leading cause of hospital-acquired infections?

A

Ps. aeruginosa

79
Q

What does ps. aeruginosa have a preference for in humans?

A

Situations where innate immunity is reduced

80
Q

What is the key to controlling pseudomonas infections?

A

Prevention

Gabe's Locomotor (9 decks)

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