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M1 Micro Quiz 2 > Gram-Negative Opportunistic Infections > Flashcards

Gram-Negative Opportunistic Infections Flashcards

1
Q

What is an opportunistic pathogen?

A

Pathogen only capable of causing disease in immunocompromised people

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2
Q

What are biofilms?

A

Dense microbial communities surrounded by an extracellular matrix; associated with most opportunistic infections

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3
Q

What is the most common opportunistic pathogen?

A

E. coli

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4
Q

What are the 4 types of clinical syndromes E. coli can cause?

A
  1. Gastrointestinal
  2. Urinary tract infections
  3. Bacteremia
  4. Meningitis
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5
Q

A bacteriurial infection is an infection in which at least ___ bacteria/ml are present in the urine.

A

100,000

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6
Q

what are the clinical features of Cystitis syndrome?

A

involves dysuria, increased urinary frequency and urgency, and suprapubic tenderness. Usually lower UTI

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7
Q

what are the clinical features of acute pylenophritis syndrome?

A

results from disseminated UTI; involves flank pain, tenderness, and fever; dysuria and increased frequency and urgency

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8
Q

What are the clinical syndromes caused by Uropathogenic E. coli (UPEC)?

A

Generally UTI

Can be cystitis or acute pylenophritis

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9
Q

describe the pathogenicity of Uropathogenic E. coli (UPEC). how does it cause disease in cells? in what types of cells?

A

Almost always ascending
involves various adhesins
not all strains are equivalent
forms “pods” or biofilm-like structures within epithelial cells of urinary tract, can replicate within cells

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10
Q

describe the virulence factors of Uropathogenic E. coli (UPEC)

A

Adhesins, LPS, capsule, motility, exotoxins including hemolysin

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11
Q

All of the Uropathogenic adhesins are mannose-resistant except one. It is ______ and causes _____ syndrome (cyctitis/pyelonephrotis).

A

Type 1 pili; cystitis

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12
Q

What are the uropathogenic E. coli (UPEC) adhesins associated with pyelonephritis?

A

P pili and F adhesin

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13
Q

What is mannose-resistant adhesion?

A

Many UTI bacteria are capable of binding mannosides of uroepithelial cells. If binding is not blocked by mannose the pilus is referred to as mannose-resistant.

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14
Q

How is adherence of E. coli measured?

A

Hemagglutination

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15
Q

______ _______ is a critical trait of bacteremic E. coli and is correlated with production of _____ capsule.

A

Serum resistance; K1

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16
Q

What is the hallmark of gram-negative bacteremia?

A

systemic reaction to endotoxin or LPS

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17
Q

Which E. coli strain is associated with neonatal meningitis?

What is its major pathogenic determinant?

A

E. coli K1
The K1 polysialic acid capsule allows the organism to escape phagocytosis. Siderophores contribute to its ability to cause disease.

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18
Q

Which opportunistic pathogen generally occurs in the lung and is associated with CF and COPD?

A

Pseudomonas aeruginosa

19
Q

what is Pyocyanin? what species of bacteria makes it?

A

A blue pigment secreted by P. aeruginosa that is also a virulence factor that generates ROS

20
Q

What toxins does P. aeruginosa secrete that contribute to its pathogenicity?

A 
Endotoxin
Exotoxins
Proteases (elastases) - lung connective tissue breakdown
Phospholipases - surfactant breakdown
21
Q

what are the physical properties of P. aeruginosa? (G+/-?, metabolic type?)

A

Gram-negative

obligate aerobe in laboratory

22
Q

While P. aeruginosa is considered an obligate aerobe, it can use _____ as an electron acceptor or ferment _______.

A

Nitrate; arginine

23
Q

Gram-negative opportunistic pathogens (7)

A
  1. Escherichia coli
  2. Pseudomonas aeruginosa
  3. Klebsiella pneumonia
  4. Enterobacter cloacae
  5. Serratia marcesens
  6. Proteus vulgaris/mirabilis
  7. Acinetobacter baumanii
24
Q

what are the clinical features of Klebsiella pneumoniae clinical syndrome?

A
  • primary pneumonia when underlying medical problems are present “red current jelly” sputum
  • urinary tract and wound infections
  • bacteremia and meningitis
  • diarrhea
25
Q

Word association: “red current jelly” sputum

A

Klebsiella pneumoniae

26
Q

What is Klebsiella pneumoniae’s main virulence factor? why this factor?

A

the capsule due to reduced phagocytosis and reduced complement susceptibility

27
Q

Capsule production can help identify K. pneumoniae based on _____ ______ _______.

A

mucoid colony morphology

28
Q

What types of infections are associated with Enterobacter cloacae?

A

burns, wounds, respiratory and urinary infections

29
Q

In what setting do Enterobacter cloacae infections occur?

A

In the hospital secondary to antibiotic therapy

30
Q

How does Enterobacter cloacae differ from Klebsiella?

A

E. cloacae is motile and less heavily encapsulated

31
Q

what are the virulence factors of Serratia marcesens?

A

MS-fimbrae, proteases, siderophores, swarming motility

32
Q

In what settings are Serratia marcesens infections likely to be seen?

A

Often nocosomial secondary to broad spectrum antibiotic therapy or instrumentation such as tracheostomy, indwelling catheters, dialysis, respirators

33
Q

What are the non-nocosomial or out-patient settings associated with Serratia marcesens?

A

heroin addicts; septic arthritis

34
Q

Prodigiosins

A

produced by Serratia and give rise to a characteristic red color

35
Q

Which gram-negative opportunistic pathogen is common in the environment?

A

Serratia marcesens

36
Q

What are the 2 characteristics of Proteus vulgaris/mirabilis that contribute to pathogenicity?

A
  1. Flagella mediate swarming motility

2. Urease synthesis leads to salt crystalization and stone formation

37
Q

What type of infection does Proteus vulgaris/mirabilis cause?

A

Urinary tract infection

38
Q

What are the physical properties of Acinetobacter baumanii?

A

oxidase negative non-fermenter, short rod

39
Q

In what setting do infections with Acinetobacter baumanii infections usually occur and what complicates their treatment?

A

Nocosomial, often associated with indwelling medical devices

Reservoirs in hospitals may exist and multi-drug resistant strains exist

40
Q

what virulence factors does Acinetobacter baumanii produce?

A

capsular polysaccharides, protein adhesins, proteolytic and lipolytic enzymes, LPS

41
Q

What types of infections does Provindencia cause?

A

Nocosomial infections of urinary tract, blood, respiratory tract, and wounds

42
Q

Which gram-negative pathogen causes neonatal meningitis and brain abscesses?

A

Citrobacter diversus

43
Q

Which gram-negative opportunistic pathogens ferment lactose? (The others don’t)

A

E. coli
K. pneumonia
E. cloacae

44
Q

Most gram-negative opportunistic pathogens are faculative anaerobes. Which gram-negative opportunistic pathogen is a non-fermenter?

A

Acinetobacter baumanii

M1 Micro Quiz 2 (12 decks)

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