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Bacteriology Lecture (Midterm- Finals) > MIDTERM: Aerobic Gram Positive Bacilli > Flashcards

MIDTERM: Aerobic Gram Positive Bacilli Flashcards

1
Q

Although several of these organisms are frequently isolated in the clinical laboratory, they are typically considered contaminants or commensals (e.g., Bacillus and Corynebacterium)

A

Aerobic Gram Positive Bacilli

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2
Q

Enumerate the spore formers bacteria

A

Bacillus anthracis
Bacillus cereus

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3
Q

Enumerate the non-spore formers bacteria

A

Corynebacterium
Listeria
Erysipelothrix
Gardnerella

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4
Q

Enumerate the Branching, non-spore-formers

A

Nocardia
Aerobic actenomycetes

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5
Q

This is also a part of the non spore formers bacteria and is formerly known as Corynebacterium equi which is an opportunistic pathogen that affects immunocompromised patients

A

Rhodococcus equi

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6
Q

Members of the genus Bacillus can be confused with
aerotolerant strains of the other primary endospore-forming genus, _______ as they are both gram positive

A

Clostridium

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7
Q

______ Is aerobic or facultative anaerobic while ______ is anaerobic

A

Bacillus spp., Clostridium, respectively

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8
Q

Enumerate at least two general characteristics of a Bacillus

A
  • Gram positive
  • Aerobic or facultative anaerobic bacilli
  • Endospores
  • Catalase positive
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9
Q

________ form endospores aerobically and anaerobically, whereas _________ form endospores anaerobically only

A

Bacillus
spp., Clostridium spp., respectively

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10
Q

What are the two groups of Bacillus spp.?

A

Bacillus anthracis &
Bacillus cereus

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11
Q

Bacillus spp. are divided into groups based on?

A

genetic identity and morphologic features

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12
Q

The causative agent of anthrax

A

Bacillus anthracis

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13
Q

Primarily a disease of wild and domestic animals including sheep, goats, horses, and cattle.

A

Anthrax

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14
Q

Humans acquire infections (anthrax) when inoculated with

A

endospores, either by traumatic introduction, injection, ingestion, or inhalation during exposure to contaminated animal products, such as hides

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15
Q

Enumerate the types of Anthrax

A
  • Cutaneous Anthrax
  • Gastrointestinal/Ingestion Anthrax
  • Inhalation Anthrax (wool sorter’s disease)
  • Injectional Anthrax
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16
Q

Accounts for most human infections and is associated with contact with infected animal products.

A

Cutaneous Anthrax

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17
Q

Infection results from close contact and inoculation of endospores through a break in the skin

A

Cutaneous Anthrax

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18
Q

This infection is typically effectively treated with antibiotics.

A

Cutaneous Anthrax

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19
Q

The typical presentation of the ulceration in cutaneous anthrax is a black, necrotic lesion known a

A

eschar

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20
Q

Incubation period of cutaneous anthrax

A

approximately 2 to 6 days

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21
Q

Mortality rate for untreated cutaneous anthrax

A

low, at approximately 1%

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21
Q

Fatalities may occur in cutaneous anthrax when the lesions form on

A

face or neck

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22
Q

These causes an obstructed airway after edema or progression to systemic disease

A

Face and neck lesions (Cutaneous anthrax)

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23
Q

Results from ingestion of endospores and presents in two forms: oral/oro-pharyngeal anthrax and gastrointestinal anthrax

A

Gastrointestinal/ Ingestion Anthrax

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24
Q

This anthrax causes lesion to appear in the buccal cavity or on the tongue, tonsils, or pharyngeal mucosa

A

oral or oro-pharyngeal anthrax (Gastrointestinal/ Ingestion Anthrax)

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24
Q

This anthrax causes lesion to develop in the mucosa of the terminal ileum or cecum

A

gastrointestinal anthrax (Gastrointestinal/ Ingestion Anthrax)

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25
Q

Its mortality rate is much higher than that of cutaneous anthrax and is usually attributed to toxemia and sepsis.

A

gastrointestinal anthrax

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26
Q

The most fatal type of anthrax

A

Inhalation Anthrax (wool sorter’s disease)

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27
Q

Inhalation Anthrax is previously referred to as

A

pulmonary anthrax, Wool sorters’ disease and ragpickers’ disease

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28
Q

In Inhalation Anthrax , the endospores are ingested by?

A

macrophages in the lungs

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29
Q

Terms used to describe respiratory infections that result from exposure to endospores during the handling of animal hides, hair, fibers, and other animal products.

A

Wool sorters’ disease and ragpickers’ disease

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30
Q

The initial, mild form of the Wool sorters’ disease or ragpickers’ disease lasts for?

A

2-3 days

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30
Q

The severe phase of this disease has a
high mortality rate

A

Wool sorters’ disease or ragpickers’ disease

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31
Q

The course of the severe phase (onset of respiratory symptoms to death) of Wool sorters’ disease or ragpickers’ disease may last only for?

A

24 hours

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32
Q

This has been considered a candidate for biological terrorism and warfare.

A

Anthrax

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33
Q

Patients can develop meningitis within 6 days after exposure to this

A

Anthrax

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34
Q

Virulence in B. anthracis is attributed to the production of?

A

plasmid-borne anthrax toxins: lethal toxin (LT), and edema toxin (ET)

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35
Q

What are the two proteins that consist Lethal toxin and edema toxin?

A

protective antigen (PA) and the functional
enzyme, lethal factor (LF) and edema factor (EF)

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36
Q

Considered opportunistic pathogens and often associated with food borne illness

A

B. cereus group

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37
Q

These are often associated with infections in immunocompromised patients who have debilitating
disease such as cancer or diabetes

A

B. cereus group

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38
Q

Associated with the ingestion of a wide variety of foods including meats, vegetables, desserts, sauces, and milk

A

B. cereus group “food poisoning”

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39
Q

A higher incidence of B. cereus is seen after the ingestion of?

A

Rice dishes

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40
Q

One of the two types of symptoms patient present after ingestion of foods infected with B. cereus

A

diarrhea and emetic (vomiting)

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41
Q

The most common type of non gastrointestinal infection caused by B. cereus

A

eye infections (Endophthalmitis)

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42
Q

Enumerate the virulence factors of B. cereus

A
  • hemolysin BL (HBL)
  • Nonhemolytic enterotoxin (Nhe)
  • cytotoxin K (Cytk) (hemolysin IV)
  • Cereulide
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43
Q

These three toxins of B. cereus are believed to act synergistically

A
  • hemolysin BL (HBL)
  • Nonhemolytic enterotoxin (Nhe)
  • cytotoxin K (Cytk) (hemolysin IV)
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44
Q

Toxin responsible for the major symptoms in the diarrheal presentation of B. cereus infection

A

Nonhemolytic enterotoxin (Nhe)

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45
Q

The _________ of illness is associated with a heat-stable, proteolysis, and acid-resistant toxin

A

emetic form

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46
Q

Heat-stable, proteolysis, and acid-resistant toxin which is produced in food

A

cereulide

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47
Q

Specimen processing:
Heat
62°C to 65°C for ____
70°C for ____
80°C for _____

A
  • 15-20 minutes (B. anthracis only)
  • 30 minutes
  • 10 minutes
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47
Q

This removes contaminating organisms, and only the spore-forming bacilli survive

A

pretreatment (alcohol shock)

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48
Q

This technique is considered an enrichment and selection procedure designed to increase the chance for laboratory isolation of the organisms.

A

Alcohol shock

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49
Q

The only clinically relevant aerobic organisms capable of producing endospores in the presence of oxygen

A

Bacillus spp.

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50
Q

Sporulation is inhibited by high concentrations of?

A

CO2 (carbon dioxide)

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51
Q

The production of spores may be induced by growth in

A

triple sugar iron (TSI), urea, or nutrient agar containing 5mg/L manganese sulfate

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52
Q

What is the special stain required to visualize endospores?

A

malachite green

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53
Q

What counterstain follows the primary stain in gram staining endospores?

A

safranin

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54
Q

The _____ stain green, and the ______ will appear pink from the secondary stain, safranin

A

endospores and vegetative cells, respectively

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55
Q

This is attributed by the fact that the endospores may appear as intracellular or extracellular clear oval structures upon Gram staining.

A

Box car or bamboo rod appearance

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56
Q

All Bacillus and related genera grow well on

A
  • 5% sheep blood agar
  • chocolate agar
  • routine blood culture media
  • nutrient broths
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57
Q

Isolates susceptible to nalidixic acid will not grow on

A

Columbia agar with nalidixic acid and colistin (CNA)

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58
Q

An additional selective agar for gram-positive organisms. Also useful for the removal of contaminating organisms and the isolation of Bacillus spp.

A

Phenylethyl alcohol agar (PEA)

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59
Q

This can be used for selection and isolation from contaminated specimens (fecal)

A

Polymyxin-lysozyme-EDTA-thallous acetate (PLET)

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60
Q

Used to induce B. anthracis capsule formation, providing a means for presumptive morphologic identification

A

Bicarbonate agar

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61
Q

The current CDC level A testing protocol for the presumptive
identification of anthrax recommends using _____ for
stools suspected to contain B. anthracis, in addition to SBA
and other commonly used media.

A

PEA agar

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62
Q

Because B. anthracis would typically be isolated from normally sterile sites, such as

A

blood, lung tissue, and CSF

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63
Q

This should be incubated
in increase carbon dioxide environment

A

Bicarbonate agar

64
Q

TRUE OR FALSE:
Increase CO2 promotes spore formation.

A

FALSE. It does not promote spore formation

65
Q

On sheep blood agar (SBA), colonies of B. anthracis appear?

A

nonhemolytic,
large (2 to 5 mm), gray, and flat with an irregular margin

66
Q

Term used to describe the colony morphology of B. anthracis.

A

Medusa head

67
Q

These have a tenacious consistency, holding tightly to the agar surface, and when the edges are lifted with a loop, they stand upright without support.

A

B. anthracis colonies

68
Q

This has been described as having the appearance or characteristic of beaten egg whites.

A

B. anthracis colonies

69
Q

This organism ferments glucose but does not ferment mannitol, arabinose or xylose

A

B. anthracis

70
Q

This produces lecithinase, grows in 7% NaCl and pH < 6 and is susceptible to penicillin (10 U/mL)

A

B. anthracis

71
Q

B. anthracis grow on?

A

Egg Yolk Agar

72
Q

Opaque zone around colonies

A

Lecithinase

73
Q

In Gelatin hydrolysis test, the hydrolyzed tube remain liquid even after freezing at?

A

4°C

73
Q

Oily sheen

A

Lipase

74
Q

This can be tested by either wet mount preparation or inoculation into motility test medium

A

Motility

75
Q

Capsule production by B. anthracis can be detected by ____________ on blood or CSF specimens or on cells isolated in media supplemented with ____________

A

India ink staining and sodium bicarbonate, respectively

75
Q

Identify:
- Susceptible to penicillin
- Positive for Lecithinase
- Negative for motility
- No hemolysis on BAP
- Negative for Gelatin hydrolysis
- Negative for growth in PEA

A

B. anthracis

76
Q

Serodiagnosis of B. anthracis is typically available for the detection of

A

PA antigen or toxin protein, LF, and EF

77
Q

Immunochromatographic test that presumptively identifies B. anthracis from blood agar within 15 minutes

A

Red Line Alert Test

78
Q

Identify:
- Resistant to penicillin
- Positive for Lecithinase
- Positive for motility
- Shows beta hemolysis on BAP
- Positive for Gelatin hydrolysis
- Positive for growth in PEA

A

B. cereus

79
Q

This test is a presumptive test and should not be used independently for the diagnosis of anthrax.

A

Red Line Alert Test

80
Q

Most rapid detection method and differentiation of B. anthracis

A

PCR

81
Q

Give the expected results in Penicillin susceptibility for:
- B. anthracis
- B. cereus

A

B. anthracis- susceptible
B. cereus- resistant

82
Q

Prevention and treatment of Anthrax

A
  • Vaccine
  • Ciprofloxacin (or doxycycline)
83
Q

Give the expected results in Growth in Phenylethyl Alc. agar for:
- B. anthracis
- B. cereus

A

B. anthracis- negative
B. cereus- positive

84
Q

Give the expected results in Lecithinase for:
- B. anthracis
- B. cereus

A

B. anthracis- positive
B. cereus- positive

85
Q

Cell-free inactivated vaccine are given in what doses and how many boosters?

A

Three primary doses followed by two boosters thereafter (0 weeks, 1month, 6 months, 12 months, and 18 months)

86
Q

Give the expected results for Fermentation of salicin:
- B. anthracis
- B. cereus

A

B. anthracis- negative
B. cereus- positive/ negative

86
Q

Recommended after aerosol exposure to B. anthracis, such as in a bioterrorist event.

A

Chemoprophylaxis with ciprofloxacin (or doxycycline)

87
Q

These are available for immunizing high-risk adults (i.e., public health laboratory workers, workers handling potentially contaminated industrial raw materials, and military personnel) against anthrax

A

Cell-free inactivated vaccine (BioThrax, Emergent Biode fense Operations, Lansing, MI)

88
Q

This organism is gram positive “club-shape” coryneform /
diptheroid, nonlipophilic, lipophilic, catalase +, and nonmotile

A

Corynebacterium (non-spore formers)

88
Q

On Gram stain, these are slightly curved, gram- positive rods with nonparallel sides and slightly wider ends, producing the described “club shape”.

A

corynebacteria

89
Q

A form of Diptheria that is often considered fastidious and grow slowly on standard culture
media

A

Lipophilic corynebacteria

89
Q

Disease caused by C. diphtheriae is referred to as

A

diphtheria

90
Q

The bacteria are carried in the upper respiratory tract and spread by droplet or hand-to-mouth contact.

A

Respiratory Diptheria

91
Q

The most common site of infection in Respiratory Diptheria

A

tonsils or the pharynx

92
Q

Some C. diptheriae cannot cause diptheria but only those who that have been infected by ________

A

bacteriophage

93
Q

Cause tissue necrosis and exudate formation triggering an inflammatory reaction

A

Diptheria

94
Q

Combination of cell necrosis and exudate forms a tough gray-to white ___________, which attaches to the tissue

A

pseudomembrane

95
Q

A form of Diptheria that consists of nonhealing ulcers with a dirty gray membrane

A

Cutaneous Diptheria

95
Q

This toxin is produced by strains of C. diphtheriae infected with a lysogenic β-phage (carrier of gene tox)

A

Diphtheria toxin

95
Q

The major virulence factor associated with C. diphtheriae

A

Diphtheria toxin

96
Q

One of the Corynebacterium species most frequently recovered from human specimens

A

C. Amycolatum

97
Q

Often been misidentified by clinical laboratories as C. striatum, C. xerosis, and C. minutissimum

A

C. Amycolatum

98
Q

Named after Johnson and Kaye. Most common cause of Corynebacterium- associated prosthetic valve endocarditis in
adults

A

C. Jeikeium

99
Q

Infections are typically limited to patients who are immunocompromised, have undergone invasive procedures, or have central line catheters or prosthetic devices

A

C. Jeikeium

100
Q

Primarily a veterinary pathogen. Human infections typically have been associated with contact with sheep and are rare

A

C. pseudotuberculosis

101
Q

The organism produces a dermonecrotic toxin that causes death of various cell types, and it can produce diphtheria toxin.

A

C. pseudotuberculosis

102
Q

Most commonly associated with UTIs, Up and incoming cause of cystitis

A

C.urealyticum

103
Q

Has been isolated from humans with diphtheria-like illness, and a significant number of isolates produce the diphtheria toxin

A

C. ulcerans

104
Q

As a veterinary pathogen, it causes mastitis in cattle and
other domestic and wild animals. Human infections are
usually acquired through contact with animals or by
ingestion of unpasteurized dairy products

A

C. ulcerans

105
Q

These are highly pleomorphic (many shapes) gram- positive bacillus that appears in palisades (cells lie in parallel rows, picket-fence, chine letter arrangement) or as
individual cells lying at sharp angles to another in “V” and “L” formations

A

C. diphtheriae

106
Q

These organisms often stain irregularly, especially when stained with methylene blue, giving them a beaded appearance.

A

C. diphtheriae

107
Q

These produce much larger colonies when cultured on 5%sheepbloodagarsupplemented with 1% Tween 80

A

lipophilic (lipid loving) species (e.g.,C. jeikeium, C. urealyticum, C. afermentans subsp. lipophi lum, C. accolens, and C. macginleyi)

107
Q

The metachromatic areas of the cell, which stainmore intensely than other parts, are called

A

Babès-Ernst granules or Volutin granules

108
Q

They represent accumulation of polymerized polyphosphates. Their presence indicates the accumulation of nutrient reserves and differs with the type of medium and the metabolic state of the individual cells

A

Babès-Ernst granules

109
Q

Demonstrate better growth in broths supplemented with rabbit serum (Corynebacterium are facultatively anarobe)

A

Lipophilic coryneform bacteria

110
Q

Can promote production of metachromatic granules because it contains egg yolk

A

Loeffler medium

110
Q

Produces brown-black colonies with a gray-brown halo

A

Tinsdale medium

111
Q

A modification of Tinsdale medium, contains
sheep red blood cells, bovine serum, cystine, and
potassium tellurite. This is also both a selective medium and a differential medium

A

Cystine-tellurite blood agar (CTBA)

111
Q

Useful for differentiating
corynebacteria because only C. diphtheriae, C. ulcerans, and C. pseudotuberculosis form a brown halo as a result of cystinase activity.

A

Cystine-tellurite blood agar (CTBA)

112
Q

All medically important corynebacteria are

A

catalase positive and nonmotile

112
Q

Inhibits many noncoryneform bacteria. When grown on CTBA

A

potassium tellurite

113
Q

Due to reduction of tellurite, corynebacteria form?

A

black or brownish colonies

114
Q

Indicators of clinical relevance include:

A

(1) isolation from normally sterile sites or multiple blood
culture bottles;

(2) isolation in pure culture or as the predominant organism from symptomatic patients who have not yielded any other known etiologic agent; and

(3) isolation from urine if present as a pure culture at
greater than 10,000 colony-forming units per milliliter
(CFU/mL) or the predominant organism at greater than 100,000 CFU/mL.

114
Q

Distinguished from the other two species by
its lack of urease production. It ferments
glucose and maltose, producing acid, but not gas, and reduces nitrate to nitrite.

A

C. diptheriae

115
Q

Colonies of this bacteria are flat and dry, have a matte or waxy appearance, and are nonlipophilic. It does not produce any halo in Tinsdale medium; negative for urease; is only able to produce acid from glucose

A

C. amycolatum

115
Q

This organism is lipophilic and a strict aerobe that is nonhemolytic, does not produce urease, and is nitrate reduction negative

A

C. jeikeium

116
Q

Produces urease and on SBA, forms small and yellowish-white colonies.

A

C. pseudotuberculosis

116
Q

Produce acid from starch and is gelatin hydrolysis positive. It does not reduce nitrate, differentiating it from C. diphtheriae, and it is urease positive

A

C. ulcerans

117
Q

Identify:
Pinpoint, nonhemolytic, white colonies have characteristic coryneform microscopic morphology. Is nitrate negative, catalase positive, and urease positive within minutes after inoculation on a Christensen urea slant

A

C. urealyticum

117
Q

For toxigenicity test, a patient may be infected with several strains at once, so testing is performed using a pooled inoculum of at least ________ is necessary

A

10 colonies

118
Q

Used to ascertain whether diphtheria antitoxin neutralizes the lethal effect of a cell-free suspension of the suspect organism

A

Guinea pig lethality test

119
Q

Utilizes the principle of immunodiffusion. A filter
paper strip impregnated with diphtheria antitoxin is buried just beneath the surface of a special agar plate before the agar hardens

A

ELEK test

120
Q

In ELEK test, after 24 hours of incubation at 37°C, the plates are examined with transmitted light for the
presence of ________________ at a 45-degree angle to the streak

A

fine precipitin lines

121
Q

A preparation of antibodies capable of toxin neutralization before its entry into the patient’s cells.

A

diphtheria antitoxin (DAT)

121
Q

Why is it critical that DAT be administered as soon as a presumptive clinical diagnosis is completed?

A

Because of hypersensitivity reactions to antibodies (proteins) produced in horses

121
Q

This is the only bacteria considered as an important human pathogen

A

Listeria monocytogenes

122
Q

Clinically significant in specific populations of immunocompromised patients as well as being associated with foodborne infections in healthy individuals.

A

Listeria monocytogenes

123
Q

Identify:
- facultative anaerobe
- catalase-positive
- nonbranching,
- oxidase-negative
- gram-positive rod

A

Listeria

124
Q

Enumerate the toxin detection methods available

A
  • Guinea pig lethality test
  • Immunodiffusion (ELEK TEST
  • Tissue culture cell test
  • ΕΙΑ
  • Detection of tox gene (PCR)
124
Q

In ELEK test, the precipitin lines indicates that the
strain produced toxin that reacted with the homologous
antitoxin. With that, state the uses of Lines 1, 2, 3, and 4

A

Line 1: the negative control

Line 2: the positive control

Line 3: an unknown organism that is a nontoxigenic strain

Line 4: an unknown organism that is a toxigenic strain

125
Q

The only effective control of diphtheria is through

A

Immunization with a multidose diphtheria toxoid prepared by inactivation of the toxin with formaldehyde

126
Q

The colonies are small, round, smooth, and translucent. They
are surrounded by a narrow zone of β-hemolysis, which may be visualized only if the colony is removed. The colonies and hemolysis resemble those seen with S. agalactiae

A

L. monocytogenes colonies

126
Q

Short, gram-positive rod that may occur singly or in
short chains, resembling streptococci

A

Listeria

127
Q

The optimal growth temperature for L. monocytogenes is ___ to ___ but growth occurs over a wide range (0.5°to45° C).

A

30° and 35° C, respectively

128
Q

Because of this, L. monocytogenes may be used to isolate from polymicrobial clinical specimens

A

cold enrichment technique (4° C)

128
Q

In CAMP test, L.monocytogenes exhibit a

A

narrow zone formation but more of a block-type of hemolysis

128
Q

Identify what listeria:
- Motile
- Ferments salicin
- Hydrolyzes esculin

A

L. monocytogenes

128
Q

This organism is also called a refrigerator bacilli

A

L. monocytogenes

129
Q

In wet mount, it exhibits tumbling motility (end-over-end motility)

A

L. monocytogenes

129
Q

“umbrella” pattern is seen when the organism is incubated at room temperature(22° to25°C)but not at 35° C

A

L. monocytogenes

130
Q

Widely distributed in nature and occasionally colonizes the human gastrointestinal tract. Many foods are contaminated with this, including milk, raw vegetables, cheese, and meats.

A

L. monocytogenes

130
Q

Outbreaks have occurred as a result of eating contaminated cheese, coleslaw, and chicken. Contaminated ice cream, hotdogs, and luncheon meats have served as vehicles for this food borne disease as well.

A

Listeriosis

131
Q

Major virulence factor. It is a pore forming toxin that reduces T-cell responsiveness.

A

Listeriolysin O

132
Q

Organism produces a bacterial surface protein, _________, that induces host cell actin polymerization

A

Act A

133
Q

Are found worldwide in a variety of vertebrate and invertebrate animals, including mammals, birds, and fish

A

Erysipelothrix rhusiopathiae

134
Q

Identify:
- gram-positive
- catalase-negative
- non–spore-forming, pleomorphic rod that has
a tendency to form long filaments

A

Erysipelothrix rhusiopathiae

135
Q

Associated with individuals
employed in occupations such as fish handlers, farmers, slaughterhouse workers, food preparation workers, and
veterinarians

A

Erysipelothrix infections

136
Q

Specimen used for Erysipelothrix

A

Tissue biopsy of the skin lesion

136
Q

The most common infection caused by E. rhusiopathiae in humans

A

Erysipeloid

Bacteriology Lecture (Midterm- Finals) (9 decks)

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