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Microbiology > Chapter 18: Haemophilus and Other Fastidious Gram-Negative Bacilli > Flashcards

Chapter 18: Haemophilus and Other Fastidious Gram-Negative Bacilli Flashcards

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1
Q

Staining Characteristic of Haemophilus spp.

A

Gram Negative

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2
Q

Appearance of Haemophilus spp. (3)

A
  • Pleomorphic
  • Small coccobacili from direct smears of clinical samples
  • Long filaments from colony growth
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3
Q

Motility of Haemophilus spp

A

Non-motile

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4
Q

Mode of Respiration and Sugar for Haemophilus spp.

A

Facultative Anaerobic, Carbohydrate Fermenter

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5
Q

Kind of Parasite on the mucous membranes of Humans and Animals

A

Obligate Parasites

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6
Q

Kind of Parasite on the mucous membranes of Humans and Animals

A

Obligate Parasites

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7
Q

8 Species of Haemophilus species associated with humans

A 
Haemophilus influenzae - “Pfeiffer’s Bacillus”
 Haemophilus parainfluenzae	
 Haemophilus haemolyticus
 Haemophilus parahaemolyticus
 Haemophilus paraphrohaemolyticus
 Haemophilus pittmaniae 
 Haemophilus aegyptius - “Koch-Weeks Bacillus”
 Haemophilus ducreyi
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8
Q

Three Pathogenic Species of Haemophilus

A

Haemophilus influenzae - Meningitis, epiglottitis

Haemophilus aegyptius - Pink Eye Conjunctivitis

Haemophilus ducreyi - Chancroid / Soft Chancre

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9
Q

General Characteristics of Haemophilus spp.

A
  • Indigenous microbiota of the healthy upper respiratory tract
  • Non-encapsulated strains of Haemophilus influenzae in healthy children average 2% of the normal bacterial biota.
  • Approximately 10% of normal bacterial biota in adults consists of Haemophilus spp.
    • Haemophilus parainfluenzae
    • Non-encapsulated Haemophilus influenzae
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10
Q

Haemophilus is derived from the Greek words ____

A

“aima” and “philia”

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11
Q

X Factor

A

hemin or hematin (“X for unknown”)

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12
Q

V factor

A

nicotinamide adenine dinucleotide [NAD] = (“V for vitamin”)

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13
Q

Haemophilus spp. with the prefix para require only ______

A

V factor for growth.

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14
Q

Both X and V factors are found within red blood cells; however, only _____ is directly available.

A

X factor

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15
Q

Haemophilus spp. that are V factor dependent do not grow on SBA because the red blood cells are still intact, and the sheep red blood cells contain ______

A

Enzymes (NADases) that hydrolyze V factor

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16
Q

Clinical laboratories use _____ for the recovery of Haemophilus spp. from clinical specimens.

A

CHOC agar

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17
Q

The lysing of the red blood cells by heat in the preparation of CHOC agar releases both _______

A

the X factor and the V factor and inactivates NADases

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18
Q
  • Phenomenon that helps in the recognition of Haemophilus spp. that require V factor is satellitism
  • occurs when organisms, like Staphylococcus aureus, Streptococcus pneumoniae, or Neisseria spp., produces V factor as a by-product of metabolism
A

Satellitism

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19
Q

Pfeiffer’s Bacillus

A

Haemophilus influenzae

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20
Q

Most significant of all virulence factors in H. influenzae

A

Capsule

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21
Q

Most significant of all virulence factors in H. influenzae

A

Capsule

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22
Q

Capsular polysaccharide serve as a basis for serologic grouping

What are the 6 serotypes?

A

A, B, C, D, E, and F

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23
Q

Serotype b capsule is a unique polymer composed of ______

A

ribose, ribitol, and phosphate (polyribitol phosphate)

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24
Q

___________ of the type b capsule are important factors in virulence

A

antiphagocytic property and anticomplementary activity

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24
Q

___________ of the type b capsule are important factors in virulence

A

antiphagocytic property and anticomplementary activity

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25
Q

Most invasive infections were caused by encapsulated strains of H. influenzae belonging to _______

A

Serotype b (Hib)

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26
Q

In unvaccinated children, type b is a leading cause of ______

A

Meningitis

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27
Q

Not all strains of H. influenzae are encapsulated, referred to as _________

A

Non-typable H. influenzae (NTHi)

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28
Q

Haemophilus influenzae is the only member of the genus that produces ________

This enzyme has the ability to cleave secretory IgA

A

Immunoglobulin A Proteases

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29
Q

Adherence mechanisms of H. influenzae

A

Studies indicate that most NTHi strains are adherent to human epithelial cells; most encapsulated serotype b strains are not adherent

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30
Q

Antibody directed against these antigens may play a significant role in human immunity

Have a paralyzing effect on the sweeping motion of ciliated respiratory epithelium

A

Outer Membrane Proteins & Lipopolysaccharides

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31
Q

Infections by encapsulated, serotype B strains (Hib) : systemic

A 
Septicemia
Meningitis
Arthritis
Epiglottitis
Tracheitis 
Pneumonia
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32
Q

Infections by non-encapsulated, non-typable Haemophilus influenzae (NTHi) : localized

A

Conjunctivitis
Sinusitis
Otitis media with effusion / middle ear infections

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33
Q
  • Widespread before the use of Hib vaccine
  • were common among children between the ages of 3 months and 6 years
  • Bloodstream invasion and bacteremic spread follow colonization of this organism in the respiratory mucous membranes
A

Meningitis

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34
Q

Symptoms of Meningitis

A

mild respiratory disease
headache
stiff neck
other meningeal signs

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35
Q

Occurs in children between 2 and 4 years old
Rapid onset, acute inflammation, and intense edema of the epiglottis
complete airway obstruction

A

Epiglottitis

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36
Q
  • life-threatening disease in young children
  • arise after an acute, viral respiratory infection; mild to moderate illness for approximately 2 to 7 days progresses rapidly
  • thick secretions can occlude the trachea
A

Bacterial Tracheitis

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37
Q

Koch-Weeks Bacillus

A

Haemophilus aegyptius

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38
Q

Disease associated with Haemophilus aegyptius

A

“Pink Eye” = Acute Purulent Conjunctivitis

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39
Q

Historical Background of Haemophilus aegyptius

A

observed in conjunctivitis exudates from Egyptians by Koch in 1883

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40
Q
  • Non-encapsulated
  • caused a severe systemic disease known as Brazilian Purpuric Fever (BPF) in Brazil in 1984
  • Disease associated :
  • conjunctivitis, primarily in pediatric populations
  • Brazilian Purpuric Fever
A

Haemophilus influenzae biogroup aegyptius

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41
Q

Characterized by:

  • recurrent or concurrent conjunctivitis
  • High fever
  • Vomiting
  • Petechial / purpural rash
  • Septicemia, shock, and vascular collapse
  • Mortality Rate : 70% within 48 hours after onset
A

Brazilian Purpuric Fever (BPF)

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42
Q

Strict human pathogen
Not part of the normal microbiota
* Extremely fastidious
* Disease associated : Chancroid / “Soft Chancre”
highly communicable sexually transmitted genital ulcer disease (GUD)
facilitates the transmission of other STDs
Incubation Period : 4 – 14 days

A

Haemophilus ducreyi

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43
Q

Clinical Manifestations of Chancroid / “Soft Chancre”:

A
  1. nonindurated, painful lesion with irregular edge
  2. generally on the genitalia or perianal areas
  3. Buboes = suppurative (pus-forming), enlarged, draining, inguinal lymph nodes
  4. Men have symptoms related to the inguinal tenderness and genital lesions
  5. Most women are asymptomatic
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44
Q
  1. found in the oral cavity
  2. very low incidence of pathogenicity
    Disease associated : endocarditis
  3. Primary Site of Infection : mitral valve
    symptoms appear approximately 1 month after routine dental procedures
A

Haemophilus parainfluenzae

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45
Q
  • indigenous microbiota of the URT of adults

* Disease associated : pharyngitis

A

Haemophilus parahaemolyticus

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46
Q

Specimen Processing & Isolation

A

sources of specimen :

  • Blood
  • CSF (for suspected meningitis)
  • middle ear exudate (for suspected otitis media)
  • joint fluids
  • upper and lower respiratory tract specimens; bronchial washing (for culture)
  • swabs from conjunctiva (for suspected conjunctivitis)
  • vaginal swabs
  • abscess drainage
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47
Q

_________, nasal and nasopharyngeal swab specimens have no clinical value in evaluation for respiratory tract infections caused by Haemophilus influenzae

A

Except in the case of patients with cystic fibrosis

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48
Q

Haemophilus spp. are ______ in nature

A

Fastidious

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49
Q

Most conventional media ___________ the growth of Haemophilus spp.

A

Do not support

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49
Q

Haemophilus spp. do not grow on

A

MAC agar

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50
Q

Haemophilus spp. die __________

A

rapidly in clinical specimens; prompt transportation and processing are vital for their isolation

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51
Q
  • genital sites first should be cleaned with sterile gauze moistened with sterile saline
  • a swab, premoistened with sterile phosphate-buffered saline, should be used to collect material __________
A

from the base of the ulcer

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51
Q
  • genital sites first should be cleaned with sterile gauze moistened with sterile saline
  • a swab, premoistened with sterile phosphate-buffered saline, should be used to collect material __________
A

from the base of the ulcer

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52
Q

as an alternative, pus can be aspirated from _______

A

buboes if they are present

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53
Q

___________ is preferred instead of using transport media / specimen processing in the laboratory should occur soon after collection for maximum recovery

A

direct plating on selective media at the bedside

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54
Q

Haemophilus ducreyi Preferred culture media:

A

Enriched CHOC medium, Nairobi biplate

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55
Q

Haemophilus ducreyi Optimum growth temperature

A

33°C

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56
Q

Haemophilus ducreyi Duration of incubation

A

7 days

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57
Q

Nairobi biplate medium components

A

GC agar base
2% bovine hemoglobin + 5% fetal calf serum + Mueller Hinton agar on one side
5% chocolatized horse blood on the other
3 mg/L of vancomycin on both sides

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58
Q

Colony Morpholoy for H. ducreyi on CHOC agar

A 
Small
Flat
Smooth
Nonmucoid
transparent to opaque
tan or yellow
Individual colonies can be pushed intact using a loop across the agar plate surface
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59
Q

Haemophilus influenzae preferred culture media:

A

CHOC Agar, or Horse Blood Bacitracin Agar

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60
Q

H. influenzae Incubation Temperature

A

33° - 37°C

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61
Q

H. influenzae duration of incubation

A

18 - 24 hrs

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62
Q

H. influenzae incubation condition :

A

CAPNOPHILIC = 5% - 10% carbon dioxide

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63
Q

H. influenzae incubation condition :

A

CAPNOPHILIC = 5% - 10% carbon dioxide

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64
Q

CHOC agar supplemented with ______ is an excellent medium for the isolation of Haemophilus spp. from respiratory specimens

A

bacitracin (300 mg/L)

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65
Q

H. aegyptius Preferred Culture Media

A

enriched CHOC agar supplemented with 1% Iso-VitaleX

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66
Q

H. aegyptius Duration of Incubation

A

4 days

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67
Q

Colony Morphology of H. influenzae on CHOC agar

NOTE : the same colony morphology may be observed from Haemophilus influenzae biogroup aegyptius

A 
Non-hemolytic
Translucent
Tannish
Moist
Smooth
Convex
“mousy” or bleach-like odor
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68
Q

For Haemophilus influenzae, encapsulated strains grow ____________

A

larger and more mucoid than the NTHi strains

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69
Q

Haemophilus parainfluenzae Colony Morphology

A

tannish and drier

medium to large size compared with H. influenzae

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70
Q

Haemophilus parahaemolyticus Colony Morphology

A

resembles H. parainfluenzae

on horse or rabbit blood agar, it is β-hemolytic

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71
Q

Microscopic Morphology of Haemophilus spp.

A
  • small, gram-negative bacilli
  • pleomorphic : coccobacilli to long filaments
  • “halos” = capsules of Haemophilus influenzae may be observed in Gram-stained direct smears as clear, non-staining areas
  • other stains that may be used :
    Acridine orange
    Methylene blue
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72
Q

Microscopic Morphology of H. ducreyi

A

“railroad tracks” / “school of fish” = Haemophilus ducreyi appearing as pale staining gram-negative coccobacilli arranged singly or in groups

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73
Q

traditional approach : using impregnated strips

A

X & V Factor Requirement

74
Q

The Haemophilus Quad Plate contains four zones

A

media with X factor only
with V factor only
with X and V factors
with X and V factors with horse red blood cells

75
Q

X & V Factor Requirement: H. influenzae

A

X, V

76
Q

X & V Factor Requirement: H. aegyptius

A

X, V

77
Q

X & V Factor Requirement: H. influenzae biogroup aegyptius

A

X, V

78
Q

X & V Factor Requirement: H. ducreyi

A

X only

79
Q

X & V Factor Requirement: H. parahaemolyticus

A

V only

80
Q

X & V Factor Requirement: H. parainfluenzae

A

V only

81
Q

X & V Factor Requirement: H. haemolyticus

A

X, V

82
Q
  • method for differentiating the heme-producing species of Haemophilus
  • can be performed in agar, in broth, or on a disk
A

Porphyrin Test

83
Q

Principle of Porphyrin Test

A

ability of the organism to convert the substrate δ-aminolevulinic acid (ALA) into porphyrins or porphobilinogen (intermediates in synthesis of X factor)
incubation temperature : 35°C
duration of incubation : 4 hrs
porphobilinogen is detected by the addition of p-dimethylaminobenzaldehyde (Kovacs’ reagent)
red color forms if porphobilinogen is present
porphyrins can be detected using an ultraviolet light with a wavelength of about 360 nm (Wood’s lamp). Porphyrins fluoresce reddish orange under ultraviolet light.

84
Q

Species that are porphyrin negative __________

A

cannot synthesize heme and are X factor-positive (require hemin) when the impregnated strip is used

85
Q

Haemophilus spp. that can synthesize heme ________

A

are porphyrin-positive (X strip negative, do not require hemin)

86
Q

Haemophilus influenzae Drugs of choice

A

cefotaxime

ceftriaxone

87
Q

Haemophilus influenzae Alternative Drugs

A 
trimethoprim-sulfamethoxazole
 imipenem
 ciprofloxacin
 chloramphenicol
 ampicillin
88
Q

For non–life-threatening H. influenzae infection :

A

amoxicillin clavulanate
oral second-generation
third-generation cephalosporin
trimethoprim-sulfamethoxazole

89
Q

Treatment : Haemophilus ducreyi

A

azithromycin
ceftriaxone
ciprofloxacin
erythromycin

90
Q

Greek aphros and philia : “foam loving

does not require, but grow better in high concentrations of CO2

most prevalent species in the HACEK group involved in endocarditis

found in dental plaque and gingival scrapings

A

Aggregatibacter aphrophilus

91
Q

__________ have been reclassified into the single species Aggregatibacter aphrophilus

A

H. aphrophilus and H. paraphrophilus

92
Q

Clinical Manifestations Aggregatibacter aphrophilus

A

fever
heart murmur, congestive heart failure
embolism

93
Q

Colony Morphology Aggregatibacter aphrophilus

A 
convex
granular
yellow
opaque zone near the center
 can either be X factor-dependent or independent
94
Q

formerly in the genus Actinobacillus

normal oral microbiota in humans

General Characteristics :
small bacilli to coccoid
gram-negative
nonmotile

A

Aggregatibacter actinomycetemcomitans

95
Q

Disease associated :
periodontitis
subacute bacterial endocarditis

divided into six serotypes (a through f) based on a surface polysaccharides; most common serotypes : a, b, c

A

Aggregatibacter actinomycetemcomitans

96
Q

grow better with increased CO2 concentration

duration of incubation : 24 – 48 hrs

colony morphology : “star shape with four to six points”

Collagenase as a virulence factor

A

Aggregatibacter actinomycetemcomitans

97
Q

toxic to polymorphonuclear cells & monocytes

A

Collagenase

98
Q

A HACEK microbe that can be isolated from

blood
lung tissue
abscesses of the mouth
brain
sinuses
A

Aggregatibacter actinomycetemcomitans

99
Q 
General characteristics :
 gram-negative bacillus
 pleomorphic
 nonmotile
 fastidious
A

Cardiobacterium hominis

100
Q 
normal microbiota of the : 
nose
mouth
throat
gastrointestinal tract
A

Cardiobacterium hominis

101
Q

Disease associated :
endocarditis, primary site of infection : aortic valve
meningitis

A

Cardiobacterium hominis

102
Q
  • grow slowly on SBA and CHOC; do not grow at all on MAC
  • Capnophilic = requires 5% CO2
  • Colony morphology :
    “pitting” may be produced on the agar
  • Microscopic morphology :
    form rosettes
    swellings
    long filaments or sticklike structures in yeast extract
A

Cardiobacterium hominis

102
Q
  • grow slowly on SBA and CHOC; do not grow at all on MAC
  • Capnophilic = requires 5% CO2
  • Colony morphology :
    “pitting” may be produced on the agar
  • Microscopic morphology :
    form rosettes
    swellings
    long filaments or sticklike structures in yeast extract
A

Cardiobacterium hominis

103
Q 
General Characteristics : 
fastidious
gram-negative
coccobacilli
grow best with increased CO2 and hemin
nonmotile
asaccharolytic
A

Eikenella corrodens

104
Q 
General Characteristics : 
fastidious
gram-negative
coccobacilli
grow best with increased CO2 and hemin
nonmotile
asaccharolytic
A

Eikenella corrodens

105
Q

_______ of the isolates of E. corrodens “pit” (make a depression) or corrode the surface of the agar

A

45%

106
Q

normal biota of the oral and bowel cavities

poor dental hygiene or oral surgery has also been associated with infections

Disease associated :
infection from human bites
“Clenched-fist Wounds”
endocarditis

A

Eikenella corrodens

107
Q 
for immunocompromised individuals :
periodontitis
meningitis
empyema
pneumonia
osteomyelitis
arthritis
postoperative tissue infections

for drug abusers :
cellulitis

A

Eikenella corrodens

108
Q

colonize the upper respiratory tract, especially the tonsils

viral infections can be a precursor to infections by these organisms

poor dental hygiene or oral surgery is associated with infection.

A

Kingella spp.

109
Q

can grow on Neisseria selective agar (e.g., modified Thayer-Martin medium) and can resemble Neisseria gonorrhoeae

A

Kingella spp.

110
Q

Four species of Kingella spp.

A

Kingella kingae
Kingella denitrificans
Kingella oralis
Kingella potus

111
Q

bacteremia, abscesses of Kingella spp

A

K. denitrificans

112
Q

predilection for bones and joints, endocarditis of Kingella spp

A

K. kingae

113
Q

Microscopic morphology Kingella spp.

A

resist decolorization in the Gram stain
coccobacillary to short bacilli
squared ends
in pairs or short chains

114
Q

family : Flavobacteriaceae

General characteristics :
fastidious, facultatively anaerobic, gram-negative bacilli
require increased CO2 for growth & isolation from blood cultures

Disease associated :
septicemia in patients with neutropenia
endocarditis (rarely)

A

Capnocytophaga spp.

115
Q

5 species are part of normal microbiota of the oral cavity of humans (Capnocytophaga spp.)

A 
C. ochracea
C. gingivalis
C. sputigena
C. haemolyticus
C. granulosa
116
Q

Capnocytophaga spp. Colony Morphology

A

Although flagella are usually absent, gliding motility can be seen on solid surfaces.

adherent and produce a yellow-orange pigment

resemble colonies of Eikenella corrodens

most are nonhemolytic except for Capnocytophaga haemolytica (β-hemolytic)

117
Q

Microscopic morphology Capnocytophaga spp.

A

thin and often fusiform (pointed ends) resembling Fusobacterium

coccoid, and curved filaments may be also seen

118
Q

General Characteristics of Pasteurella spp.

A

normal flora of respiratory tract and oral cavity of birds and mammals
fastidious
gram-negative
nonmotile
facultative anaerobic
coccobacilli that appear ovoid, filamentous, or as bacilli
Bipolar staining / “safety pin” appearance = when the poles of the cells are more intensely stained is frequently observed

119
Q

Most common isolate in Pasteurella spp.

A

Pasteurella multocida

120
Q

5 serogroups of Pasteurella spp

A

A, B, D, E, and F

121
Q

3 Subspecies of Pasteurella spp.

A

multocida
septica
gallicida

122
Q

4 other clinical species of Pasteurella

A

Pasteurella canis
Pasteurella stomatis
Pasteurella dagmatis
Pasteurella bettyae

123
Q 
Disease associated :
* Pasteurellosis = zoonotic disease; acquired from exposure to infected animals or products made from infected animals
* most common : cutaneous infection
* systemic infections :
Septicemia
Arthritis
Endocarditis
Osteomyelitis
Meningitis
A

Pasteurella spp.

124
Q

Biochemical Test Results Pasteurella spp.

A 
catalase positive
oxidase positive
indole positive
glucose fermenter 
fructose fermenter
weak to moderate acid production
non-gas producer
125
Q

Colony morphology Pasteurella spp.:

on CHOC & SBA

A

grayish colonies

126
Q

Pasteurella spp. on SBA only

A

optimum temperature : 37°C

mucoid after 24 hrs

production of a narrow green to brown halo around the colony after 48 hrs

127
Q

“Bang’s Bacillus”

A

Brucella

128
Q

considered potential bioterrorism agent / category B select biological agents by the CDC

normal flora of respiratory tract and oral cavity of birds and mammals

A

Brucella spp.

129
Q

populations at risk :
people handling animals & animal products
laboratory workers

Disease associated :
zoonotic disease that is found throughout the world
Undulant Fever / “Malta Fever”

A

Brucella spp.

130
Q

Brucella spp. Modes of Transmission

A

aerosol
percutaneous
oral routes

131
Q

Rare documented modes of transmission (Brucella spp.)

A

sexual contact

breast feeding

132
Q

three clinical stages of Brucella spp:

A

acute
subchronic
chronic

133
Q

Identify the Disease Phase:

1 – 4 weeks after exposure 
fever
malaise
headache
anorexia
myalgia
A

Acute Phase of Brucella spp

134
Q

Identify the Disease Phase:

within a year
undulating fevers = normal temperatures in the morning followed by high temperatures in the afternoon / evening
arthritis
epididymoorchitis

A

Subchronic / Undulant Form of Brucella spp

135
Q

Identify the Disease Phase:

1 year after exposure
depression
arthritis
chronic fatigue syndrome

A

Chronic Phase of Brucella spp

136
Q

four species associated with humans (Brucella spp.)

A

Brucella melitensis
Brucella abortus
Brucella suis
Brucella canis

137
Q

two additional species isolated from marine animals (Brucella spp)

A

Brucella ovis

Brucella neotomae

138
Q

General characteristics of Brucella spp:

A 
small 
 gram-negative
 aerobic
 nonmotile
 unencapsulated
 non-spore former
 appear as coccobacilli or bacilli
 facultative intracellular pathogens; can reside within phagocytic cells
must be handled under biosafety level 3 conditions
139
Q

Sources of specimen of Brucella spp

A

blood

bone marrow

140
Q

Appropriate culture media for Brucella spp

A

SBA
CHOC
Modified Thayer-Martin
Martin-Lewis

141
Q

duration of incubation for Brucella:

A

18 hrs

142
Q

plates should be kept for _______ before reporting as negative (Brucella spp)

A

4 days

143
Q

Biochemical Test Results for Brucella spp:

A

oxidase positive
catalase positive
urease positive

144
Q

Three subspecies of Francisella tularensis

A

subsp. tularensis (type A)
subsp. holarctica (type B)
subsp. mediasiatica

145
Q

Disease associated with Francisella tularensis

A

Tularemia
zoonotic disease
rabbit fever
deerfly fever / lemming fever / water rat trappers’ disease

146
Q

modes of transmission for Francisella tularensis

A 
ingestion
inhalation
arthropod bite
contact with infected tissues
person-to-person
147
Q

most common form of tularemia

A

Ulceroglandular
ulcer forms at the site of inoculation
enlargement of the regional lymph nodes

148
Q

other forms of tularemia

A 
pulmonary
glandular
oropharyngeal
oculoglandular
typhoidal forms
149
Q

Francisella tularensis is a CDC ________

A

category A select biological agent

150
Q

General Characteristics Francisella tularensis

A 
small
 nonmotile
 non–sporeforming
 gram-negative
 bacilli or coccoid 
 strict aerobes 
 fastidious; requires the following supplements :
 cysteine
 cystine
 thiosulfate
151
Q

appropriate culture media Francisella tularensis

A 
CHOC
 Modified Thayer-Martin
 Buffered Charcoal Yeast Extract (BCYE)
 Mueller-Hinton
 Tryptic Soy Broth (TSB)

NOTE : MAC and EMB agars do not support Francisella tularensis growth

152
Q

Francisella tularensis Colony Conditions and Colony Morphology

A

optimum temperature : 37°C
duration of incubation : 48 hrs
Plates should be checked daily for 14 days.

Colony Morphology :
gray-white
smooth
raised

153
Q

Virulence factor of Legionella pneumophila

A

ability to enter, survive, and multiply within the host’s cells, especially bronchoalveolar macrophages
production of proteolytic enzymes

154
Q

Disease associated with Legionella pneumophila

A

Legionnaires’ Disease = febrile disease + pneumonia

Pontiac Fever = febrile disease only, no pulmonary involvement

155
Q

Legionnaires’ Disease / Legionellosis

A 
incubation period : 2 – 10 days
 predominant manifestation : pneumonia
 “atypical pneumonia”
 most cases are brought by serogroup 1
 also implicated in human infections :
 Legionella pneumophila serogroups 4 and 6
 Legionella longbeachae
 Legionella micdadei
156
Q

Clinical Manifestations Legionella pneumophila:

A 
nonproductive cough
fever
headache
myalgia
pulmonary infiltrates develop
bloody sputum
 dissemination via the circulatory system = extrapulmonary infections
157
Q

Clinical Manifestations Legionella pneumophila:

A 
nonproductive cough
fever
headache
myalgia
pulmonary infiltrates develop
bloody sputum
 dissemination via the circulatory system = extrapulmonary infections
158
Q

incubation period : 2 days
flu-like symptoms : fever, headache, myalgia
last 2 to 5 days
subside without medical intervention

A

Pontiac Fever

159
Q

factors that allow Legionella spp. to colonize water supplies:

A

can tolerate chlorine concentrations of 3 mg/L
can multiply over the temperature range of 20° C to 43° C
can survive for varying periods at 40° C to 60° C
can adhere to pipes, rubber, plastics, and sediment
persists in piped water systems even when flushed
ability to survive and multiply within free-living protozoa and in the presence of commensal bacteria and algae

160
Q

Specimen Collection & Handling for Legionella

A 
sources of specimen :
 sputum
 bronchoalveolar lavage
 bronchial washings 
 environmental sources

When delays of more than 2 hours between collection and processing are unavoidable, specimens should be refrigerated.

if delays take several days : freeze @ −70° C

161
Q

Microscopic Examination of Legionella

A

pleomorphic, weakly staining, gram-negative bacilli

162
Q

Isolation & Identification of Legionella

A

Acid treatment must first be done on specimens contaminated by other bacteria = enhances isolation of Legionella spp.
aliquot of the specimen is first diluted 1 : 10 with 0.2 N KCl-HCl
allowed to stand for 5 minutes
proceed with inoculation to culture media

optimum incubation temperature : 35° C to 37° C

duration of incubation : at least 7 days;

colonies usually visible in 3 - 5 days

fastidious, aerobic, do not grow on SBA

require L-cysteine; most preferred culture media : Buffered Charcoal Yeast Extract (BCYE) with L-cycteine

163
Q

Colony Morphology of Legionella

A 
grayish white or blue-green
 convex
 glistening
 approx. 2 to 4 mm in diameter
 “ground-glass” appearance
164
Q

Identification Methods for Legionella

A

L-cysteine requirement
Gram stain
Direct Fluorescence Antibody (DFA)

165
Q

two species implicated in human infections in Bordetella spp

A

Bordetella pertussis

Bordetella parapertussis

166
Q

six other species of Bordetella spp

A

Bordetella bronchiseptica
opportunistic pathogen

Bordetella avium
wild & domesticated animal pathogen

Bordetella hinzii
avian commensal

Bordetella holmesii immunocompromised bacteremia

Bordetella petrii

Bordetella trematum
wound & ear infections

167
Q

General Characteristics of Bordetella spp.

A

small gram-negative bacilli or coccobacilli
obligate aerobic bacteria
optimum growth temperature : 35° C to 37° C
non-carbohydrate fermenter
oxidize amino acids
catalase producer (variable for Bordetella pertussis)
relatively inactive in biochemical test systems

168
Q

inhibited by fatty acids, metal ions, sulfides, and peroxides, constituents found in many media

require protective substances; charcoal, blood, starch

A

Bordetella pertussis

169
Q

Virulence Factors of Bordetella pertussis

A

Filamentous hemagglutinin (FHA) and pertactin

Pertussis toxin (PT)

Adenylate cyclase toxin

Tracheal cytotoxin

170
Q

facilitate attachment to ciliated epithelial cells

A

Filamentous hemagglutinin (FHA) and pertactin

171
Q

protein exotoxin; modifies host proteins by adenosine diphosphate–ribosyl transferase

A

Pertussis toxin (PT)

172
Q

inhibits host epithelial & immune effector cells by inducing supraphysiologic concentrations of cyclic adenosine monophosphate

A

Adenylate cyclase toxin

173
Q

causing ciliostasis, inhibiting DNA synthesis, and promoting cell death

A

Tracheal cytotoxin

174
Q

incubation period : 7 – 10 days or 1 – 3 weeks

three phases : catarrhal, paroxysmal, convalescent

A

Pertussis / “Whooping Cough”

175
Q

sneezing, mild cough, runny nose, conjunctivitis; apnea & respiratory distress for infants; highly infectious stage

A

Catarrhal

176
Q

severe, repetitive coughing + characteristic “whoop” sound at the end due to rapid gasping for air. Young children might experience apnea, pneumonia, or both and require aid in maintaining a patent airway.

A

Paroxysmal

177
Q

within 4 weeks of onset with a decrease in frequency and severity of the coughing spells

A

Convalescent

178
Q

contain the structural gene for PT but do not express the complete operon.

generally causes a similar disease as pertussis with milder symptoms.

A

Bordetella parapertussis

179
Q

Specimen Collection & Handling for Bordetella

A

sources of specimen : nasopharyngeal aspirate / swabs

acceptable swab material : calcium alginate or Dacron polyester + flexible wire shaft

two swabs are collected, one through each of the external nares; the swabs should be inserted as far back as possible into the nasopharynx, rotated, held a few seconds, and then gently withdrawn

180
Q

Methods for Bordetella

A

culture
DFA
PCR

181
Q

Staining Procedure for Bordetella

A

two-minute safranin or 0.2% basic fuchsin as counterstain enhances visibility

DFA staining may also be used:
should be used only along with culture because the lack of sensitivity diminishes the clinical utility of a negative result, and false-positive results can occur
DFA should not be used as a replacement for culture

182
Q

preferred culture media for Bordetella spp

A

Bordet-Gengou Potato Infusion Agar with glycerol and horse or sheep blood

Regan-Lowe selective agar with charcoal agar supplemented with 10% horse blood and 40 mg/L cephalexin

183
Q

optimum incubation temperature for Bordetella spp

A

35° C

184
Q

duration of incubation for Bordetella spp

A

7 days; B. pertussis colonies are detected in 3 – 5 days; B. parapertussis colonies are detected in 1 day or sooner

185
Q

Colony Morphology of Bordetella spp.

A

small & shiny

“mercury droplets”

Microbiology (2 decks)

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