Oxidase negative, Gram-Negative Bac Flashcards

1
Q

Characteristics of Enterobacterales

A

Oxidase negative, Gram-Negative Bacilli

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2
Q

Opportunistic pathogens except for overt/true pathogens

A

E. coli (Diarrheagenic), Salmonella, Shigella, Plesiomonas, and Yersinia

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3
Q

Non-motile members of Enterobacterales

A

Shigella, Klebsiella, Yersinia (motile at 25°C)

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4
Q

Oxidase positive exception in Enterobacterales

A

Plesiomonas

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5
Q

General biochemical reactions for Enterobacterales

A

Catalase (+), Nitrate reduction (+), Glucose fermenters

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6
Q

Rapid lactose fermenters (EEK)

A

E. coli, Enterobacter, Klebsiella

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7
Q

Late lactose fermenters (S.C.Se)

A

Serratia, Citrobacter, Salmonella enterica subsp. arizonae (TSI may be K/A to A/A)

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8
Q

Non-lactose fermenters (SalShiYE HafPMP)

A

Salmonella, Shigella, Yersinia, Hafnia, PMP group

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9
Q

Enzymes in rapid lactose fermenters

A

β-galactoside permease and β-galactosidase

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10
Q

Enzymes in late lactose fermenters

A

β-galactosidase only

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11
Q

Enzymes in non-lactose fermenters (NLF)

A

No β-galactosidase

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12
Q

Kauffman-White classification for somatic antigen (O antigen)

A

Located in cell wall, heat stable, useful for E. coli and Shigella serotyping

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13
Q

Kauffman-White classification for flagellar antigen (H antigen)

A

Located in flagella, heat labile, useful for Salmonella serotyping

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14
Q

Kauffman-White classification for capsular antigen (Vi/K antigen)

A

Located in capsule, heat labile, useful for detecting K1 antigen of E. coli and capsular antigen of S. typhi

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15
Q

1 cause of community-acquired and hospital-acquired UTI, most common gram-negative healthcare-associated infections, and gram-negative sepsis

A

E. coli

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16
Q

2 cause of neonatal meningitis (K1 antigen + E. coli)

A

E. coli

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17
Q

1 in Traveler’s diarrhea, Childhood diarrhea, Montezuma’s revenge, Profuse watery diarrhea (Cholera-like diarrhea)

A

ETEC - Enterotoxigenic E. coli

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18
Q

Virulence of ETEC

A

Pili; Heat-Stable (ST) and Heat-Labile (LT) toxin; Cholera-like toxin (water and electrolyte secretion)

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19
Q

Strains for ETEC

A

E. coli O4, O8, O25

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20
Q

Oversecretion of cyclic adenosine monoPO4 (cAMP)

A

ETEC

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21
Q

EPEC (Enteropathogenic E. coli - mucoidal) Virulence Factor

A

Pathogenicity island virulence factors: Bundle of pili, intimin, toxins; Loss of microvilli

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22
Q

Clinical Manifestations of EPEC

A

Infantile diarrhea, Mucoidal diarrhea, Can be in Infant formula

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23
Q

Strains for EPEC

A

E. coli O55, O111, O114

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24
Q

EPEC is commonly seen in

A

infants in low-income nations

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25
Q

Shigella-like E. coli

A

Enteroinvasive E. coli (EIEC)

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26
Q

Virulence of EIEC

A

Invades large intestine in a manner identical to Shigella; Invasin toxin; Large plasmid (Sereny test +)

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27
Q

Clinical Manifestations of EIEC

A

Dysentery (necrosis, inflammation, and ulceration of large intestine); Shigella-like manifestations

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28
Q

Strain for EIEC

A

E. coli O124, O143, O164

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29
Q

EIEC is commonly seen in

A

Young children in areas with poor sanitation

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30
Q

Shiga-like toxin, Verotoxin/Verocytotoxin

A

Enterohemorrhagic E. coli (EHEC, VTEC, STEC)

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31
Q

Disease caused by EHEC / VTEC / STEC

A

Bloody diarrhea, Hemolytic Uremic Syndrome (H.U.S.), Hemorrhagic colitis

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32
Q

Strains for EHEC / VTEC / STEC

A

E. coli O157:H7, O26

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33
Q

EHEC / VTEC / STEC is commonly seen in

A

Undercooked hamburger, unpasteurized dairy products, apple cider, bean sprouts, spinach, cookie dough

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34
Q

MUG Test - E. coli Positive

A

All E. coli shows electric blue fluorescence EXCEPT E. coli O157 (No fluorescence)

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35
Q

Growth on Sorbitol MAC

A

All E. coli ferments sorbitol (Pink) EXCEPT E. coli O157 (Colorless)

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36
Q

Detection of E. coli O157

A

Use O157 Anti-serum to type the bacteria

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37
Q

Virulence of EAEC (Enteroaggregative E. coli)

A

Clumped/aggregates in intestine through pili; Watery diarrhea, Stacked brick appearance

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38
Q

Virulence of DAEC (Diffusely-adherent E. coli)

A

Diffuse patterns on HeLa or Hep2 cells; Causes diarrhea mostly in children

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39
Q

1 Cause of Uncomplicated UTI

A

Uropathogenic E. coli (UPEC)

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40
Q

K1 Antigen Positive E. coli

A

Meningitis/sepsis-associated E. coli (MNEC)

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41
Q

Condition

A

Details

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42
Q

Source of Contamination

A

Ingestion of contaminated poultry products (milk, eggs, dairy)

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43
Q

Main species of Salmonella spp.

A

Salmonella enterica and Salmonella bongori (animals)

44
Q

Subspecies of S. enterica

A

S. enterica subsp. enterica (I): serotype Typhi, Enteritidis, Paratyphi A, B, C, Cholerasuis, Typhimurium

45
Q

Other subspecies of S. enterica

A

S. enterica subsp. salamae (II), arizonae (IIIa), diarizonae (IIIb), houtenae (IV), indica (VI)

46
Q

Non-motile Salmonella

A

Salmonella serotype Gallinarum and Typhi

47
Q

Salmonella not producing H2S

A

Salmonella serotype Paratyphi A

48
Q

Persistence of Typhi/Paratyphi

A

Gall bladder (gallstones)

49
Q

Treatment for chronic carriers with gallstones

A

Cholecystectomy

50
Q

Sampling for Salmonella (1st week)

A

Blood

51
Q

Sampling for Salmonella (2nd-3rd week)

A

Stool

52
Q

Sampling for Salmonella (3rd week)

A

Urine

53
Q

Enteric fever (Typhoid) source

A

Contaminated food from food handlers that are carriers (Typhoid Mary)

54
Q

Long-term carrier site for Typhoid

A

Gall bladder

55
Q

Common cause of Enteric fever

A

S. enterica subsp. enterica serotype Typhi

56
Q

Symptoms of Typhoid Fever

A

Malaise, anorexia, myalgia, severe frontal headache

57
Q

Complications of Typhoid Fever

A

Necrotizing cholecystitis

58
Q

Hallmark for Typhoid Fever

A

Rose spots during the second week of fever

59
Q

Stool characteristics in Typhoid Fever

A

Pea soup stool

60
Q

Source of Contamination

A

Ingestion of contaminated poultry products (milk, eggs, dairy)

61
Q

Main species of Salmonella spp.

A

Salmonella enterica and Salmonella bongori (animals)

62
Q

Subspecies of S. enterica

A

S. enterica subsp. enterica (I): serotype Typhi, Enteritidis, Paratyphi A, B, C, Cholerasuis, Typhimurium

63
Q

Other subspecies of S. enterica

A

S. enterica subsp. salamae (II), arizonae (IIIa), diarizonae (IIIb), houtenae (IV), indica (VI)

64
Q

Non-motile Salmonella

A

Salmonella serotype Gallinarum and Typhi

65
Q

Salmonella not producing H2S

A

Salmonella serotype Paratyphi A

66
Q

Persistence of Typhi/Paratyphi

A

Gall bladder (gallstones)

67
Q

Treatment for chronic carriers with gallstones

A

Cholecystectomy

68
Q

Sampling for Salmonella (1st week)

A

Blood

69
Q

Sampling for Salmonella (2nd-3rd week)

A

Stool

70
Q

Sampling for Salmonella (3rd week)

A

Urine

71
Q

Enteric fever (Typhoid) source

A

Contaminated food from food handlers that are carriers (Typhoid Mary)

72
Q

Long-term carrier site for Typhoid

A

Gall bladder

73
Q

Common cause of Enteric fever

A

S. enterica subsp. enterica serotype Typhi

74
Q

Symptoms of Typhoid Fever

A

Malaise, anorexia, myalgia, severe frontal headache

75
Q

Complications of Typhoid Fever

A

Necrotizing cholecystitis

76
Q

Hallmark for Typhoid Fever

A

Rose spots during the second week of fever

77
Q

Stool characteristics in Typhoid Fever

A

Pea soup stool

78
Q

Acute gastroenteritis (food poisoning) cause

A

S. enterica subsp. enterica

79
Q

Outbreak of Salmonella Typhimurium

A

Contaminated peanut butter, crackers, and cereals

80
Q

Signs and symptoms of acute gastroenteritis

A

Nausea, vomiting, fever, chills, watery diarrhea, abdominal pain

81
Q

Biochemically inert bacteria closely related to E. coli

A

Shigella spp.

82
Q

Mode of contamination for Shigella spp.

A

Four F’s (Flies, Fingers, Food, Fecal)

83
Q

Most virulent Shigella spp. and virulence factor

A

S. dysenteriae (subgroup A); Shiga toxin

84
Q

Disease caused by S. dysenteriae (group A)

A

Bacillary dysentery

85
Q

Biochemical reactions for S. dysenteriae

A

Negative for ONPG, Ornithine Decarboxylase, Mannitol fermentation

86
Q

Common pathogenic isolate and virulence factor

A

S. flexneri; Pathogenic

87
Q

Association with Gay bowel syndrome

A

S. flexneri

88
Q

Biochemical reactions for S. flexneri and S. boydii

A

Positive for Mannitol fermentation, Negative for Ornithine Decarboxylase and ONPG

89
Q

Virulence of Shigella boydii

A

Pathogenic, less incidence

90
Q

Dysentery-causing Shigella spp.

A

S. boydii, S. sonnei

91
Q

Biochemical reactions for S. sonnei

A

Positive for ONPG, Ornithine Decarboxylase, Mannitol fermentation

92
Q

Handling encapsulated Shigella isolates

A

Capsule weakens agglutination. Suspend in saline, heat at 100°C for 15-30 mins, cool, and retype with antisera

93
Q

Class A bioterrorism agent, Vector: Oriental rat flea, Reservoir: Rats (Non-motile, Urease negative)

A

Yersinia pestis

94
Q

Most common form of Yersinia pestis - formation of buboes in the axilla or groin

A

Bubonic/Glandular plaque

95
Q

Pulmonary plaque: pleural thickening with a holly leaf appearance, causative agent

A

Yersinia pestis

96
Q

Infection through undercooked pork, pork intestine, vacuum-packed meat and chicken, dairy products like milk and chocolate, and handling pets

A

Yersinia enterocolitica subsp. enterocolitica

97
Q

Motile at 25°C, Urease positive, Ornithine and Sucrose positive

A

Yersinia enterocolitica subsp. enterocolitica

98
Q

Causative agent of Waterborne Enterocolitis (gastroenteritis), Appendicitis-like syndrome (Pseudoappendicitis)

A

Yersinia enterocolitica subsp. enterocolitica

99
Q

Agent of rodents, Reservoir: Birds, Motile at room temperature, Urease positive, Ornithine and Sucrose negative

A

Yersinia pseudotuberculosis

100
Q

Human infection involves septicemia with lymphadenitis

A

Yersinia pseudotuberculosis

101
Q

Pathogenic ingestion of contaminated seafood, oysters, shrimps, water; entry through skin cuts

A

Plesiomonas shigelloides

102
Q

Plesiomonas shigelloides cross-reacts with

A

Shigella antigen (similar to E. coli)

103
Q

Diarrhea, inflammatory bowel syndrome in HIV patients, neonatal meningitis, septicemia

A

Plesiomonas shigelloides

104
Q

The only oxidase-positive member of Enterobacteriaceae

A

Plesiomonas shigelloides

105
Q

IMViC reaction of Plesiomonas shigelloides is similar to

A

E. coli (IMViC: +, +, -, -; TSI: K/A H2S(-))