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Bacte LEC > Haemophilus, HACEK, Legionella & Other Fastidious Gram-Negative Bacilli > Flashcards

Haemophilus, HACEK, Legionella & Other Fastidious Gram-Negative Bacilli Flashcards

1
Q

(members of the family Pasteurellaceae)

A

Haemophilus
Actinobacillus
Pasteurella
Aggregatibacter

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2
Q

• Now dominant etiologies of infective endocarditis

A

Haemophilus, Actinobacillus, Pasteurella & Aggregatibacter

(members of the family Pasteurellaceae)

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3
Q

, an emerging cause of brain abscesses

A

Aggregatibacter aphrophilus

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4
Q

• Reside in the human oral cavity and nasopharynx;

some with enhanced capacity to cause ENDOCARDITIS.

A

HACEK - Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, & Kingella

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5
Q

• 5 species inhabit human oral cavity,

2 species in oral cavities of dogs & cats

A

• Capnocytophaga

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6
Q

• cause zoonoses

A

Pasteurella
Brucella
Francisella

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7
Q

• GN pleomorphic, small coccobacilli in direct smears of clinical material to long filaments in stained smears of colony growth

  • Nonmotile, facultatively anaerobe, carbohydrate fermenters, generally oxidase+, generally catalase+, nitrate reducers

• Obligate parasites of the mucous membranes (URT) of humans & animals

A

Haemophilus species

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8
Q

Haemophilus species

8 species:

A

H. influenzae
H. parainfluenzae
H. haemolyticus
H. paraphrohaemolyticus
H. pittmaniae
H. aegyptius
H. ducreyi
H. segnis (now renamed to Aggregatibacter segnis)

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9
Q

2 former members,_____ were moved into the genus Aggregatibacter & combined in a single species - Aggregatibacter aphrophilus.

A

H. aphrophilus & H. paraphrophilus

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10
Q

Greek word “Blood lover”

Require both or either growth factors present in the blood:

A

Haemophilus

• Hemin or hematin = X factor
• Nicotinamide adenine dinucleotide (NAD) = V factor

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11
Q

Do not grow in pure culture on SBA

A

Haemophilus

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12
Q

СНОС agar - lysing RBCs by heat releases X & V factors & inactivates NADases in sheep blood

A

Haemophilus

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13
Q

Satellitism
a recognized phenomenon by…

A

H. influenzae

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14
Q

• On SBA plates, tiny colonies of Haemophilus appears when mixed with Staphylococcus aureus/ Streptococcus pneumoniae/ Neisseria spp.

(exogenous sources of the V factor as by-product of metabolism & obtains X factor from the sheep blood).

A

Satellitism

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15
Q

Haemophilus influenzae aka

A

Pfeiffer’s bacillus

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16
Q

Haemophilus

• The major pathogen within the genus with wide pathogenic potential.

A

Haemophilus influenzae (Pfeiffer’s bacillus)

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17
Q

Haemophilus influenzae (Pfeiffer’s bacillus)

Virulence factors:

A

• Capsule - most significant; antigenic types a, b, c, d, e, f
• IgA proteases
• Adherence (fimbriae, other structures)
• Outer membrane proteins & LPS

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18
Q

H. influenzae

Capsule - most significant; antigenic types a, b, c, d, e, f
>__________ - most invasive infections in children before the widespread use of vaccines; now occasionally seen in over age 65 years
>________ - leading cause of meningitis among unvaccinated children

> ________ - composed of polyribitol phosphate
Not all strains are encapsulated -_______

A

H. influenzae serotype b (Hib)

Hib

Hib capsule

nontypable H. influenzae (NTHi)

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19
Q

H. influenzae

Encapsulated Strains

A

Septicemia
Septic arthritis
Pericarditis
Pneumonia
Cellulitis

Meningitis
Osteomyelitis

Epiglottitis
Tracheitis

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20
Q

H. influenzae

Non-encapsulated Strains

A

Otitis media with effusion
Conjunctivitis
Sinusitis
Bacteremia
Pneumonia

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21
Q

Infections Associated with Other Haemophilus Spp.

  • “pinkeye disease,” an acute, contagious conjunctivitis
A

• H. aegyptius (Koch-Weeks bacillus)

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22
Q

Infections Associated with Other Haemophilus Spp.

  • conjunctivitis in pediatric populations and Brazilian purpuric fever
A

• H. influenzae biogroup aegyptius

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23
Q

Infections Associated with Other
Haemophilus Spp.

  • strictly human pathogen, agent of chancroid (soft chancre), a highly communicable sexually transmitted genital ulcer disease (GUD) [should test also for HIV, syphilis & herpesvirus]
A

• H. ducreyi

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24
Q

Infections Associated with Other Haemophilus Spp.

  • otitis media, acute sinusitis, rarely endocarditis
A

• H. parainfluenzae

25
Q

Infections Associated with Other Haemophilus Spp.

  • pharyngitis
A

• H. parahaemolyticus

26
Q

(Koch-Weeks bacillus)

A

H. aegyptius

27
Q

Haemophilus: Laboratory Diagnosis
Specimen processing & Isolation

• Specimens:

A

blood
CSF
middle ear exudate
joint fluids
upper/lower respiratory tract specimens
bronchial washings
swabs from conjunctivae
vaginal swabs
abscess drainage

28
Q

(2) , die rapidly.

Prompt transportation and processing are vital.

A

• Haemophilus spp., H. ducreyi

29
Q

Haemophilus: Laboratory Diagnosis
Specimen processing & Isolation

Primary medium: (agar, temperature, CO2);

for respiratory specimens, supplement with______

A

CHOC agar, 33-37°C, 5%-10% CO2

bacitracin (300mg/L)

30
Q

Haemophilus: Laboratory Diagnosis
Specimen processing & Isolation

  • enriched CHOC medium or Nairobi biplate (half plate: GC agar base with 2% bovine hemoglobin and 5% fetal calf serum; the other half: MHA with 5% chocolatized horse blood; both contains 3mg/L vancomycin); 33°C for 7 days
A

• H. ducreyi

31
Q

Haemophilus: Laboratory Diagnosis
Specimen processing & Isolation

  • require special media enriched CHOC agar with 1% Iso VitaleX or Vitox; at least 4 days incubation.
A

• H. aegyptius

32
Q

half plate: GC agar base with 2% bovine hemoglobin and 5% fetal calf serum;

the other half: MHA with 5% chocolatized horse blood; both contains 3mg/L vancomycin

A

Nairobi biplate

33
Q

Haemophilus: Laboratory Diagnosis
Colony Morphology

TRANSLUCENT, TANNISH, MOIST, SMOOTH, CONVEX, with a distinct “MOUSY” or BLEACHLIKE odor.

Encapsulated strains larger, more mucoid than NTHi strains.

A

H. influenzae (and H. aegyptius) on CHOC:

34
Q

Haemophilus: Laboratory Diagnosis
Colony Morphology

: tannish, drier, medium to large size; are non-hemolytic

A

• H. parainfluenzae

35
Q

Haemophilus: Laboratory Diagnosis
Colony Morphology

: similar to H. parainfluenzae but beta hemolytic on horse or rabbit blood agar

A

• H. parahaemolyticus

36
Q

Haemophilus: Laboratory Diagnosis
Colony Morphology

: tan or yellow, small, flat, smooth, transparent to opaque colonies

A

• H. ducreyi

37
Q

Haemophilus: Laboratory Diagnosis
Colony Morphology

distinct “MOUSY” or BLEACHLIKE odor.

A

H influenczae

38
Q

Haemophilus: Laboratory Diagnosis
Microscopic Morphology

• Often stains faint pink, with Gram stain: small, gram-negative coccobacilli in clinical specimens to long filaments in colonies
• Capsules of_______ - clear, nonstaining halos in purulent secretions
• (2) stains may help detect Haemophilus.

A

H. influenzae

Acridine orange or methylene blue

39
Q

Haemophilus: Laboratory Diagnosis
Microscopic Morphology

  • Gram stain: school of fish or railroad tracks, fingerprints, pale-staining, small GN coccobacilli in chains
A

H. ducreyi

40
Q

Haemophilus: Laboratory Diagnosis
Laboratory Identification

FIRST CLUE:

A

pleomorphic GN coccobacilli on CHOC, NO GROWTH ON SBA & MAC in pure culture.

41
Q

• X and V growth factor test, porphyrin, oxidase, catalase, biochemicals, hemolysis
• CSF detection for capsular antigens (type b capsular Ag, i.e., Directigen Meningitis Combo Test Kit); also test for beta lactamase
• Automated commercial systems, ie, Haemophilus biotyping within 4 hours & HACEK identification by MALDI-TOF MS (matrix-assisted laser desorption/ionization-time-of-flight mass spectrophotometry

A

Haemophilus: Laboratory Diagnosis
Laboratory Identification

42
Q

Haemophilus: Laboratory Diagnosis
Laboratory Identification

X Factor and V Factor Requirements
• Use of impregnated strips or disks

• Care not to use X-factor containing medium to prevent erroneous results
• H. influenzae may be mistaken for______
• H. influenzae do not require_____ when grown anaerobically but still require_____

A

H. parainfluenzae

heme; NAD

43
Q

Haemophilus: Laboratory Diagnosis
X Factor and V Factor Requirements

• Isolates identified based on the factors required for growth & presence of____
• Use of______ or _____ media, ______ and ______impregnated strips/disks. Incubate at_____ with CO2 for_____. Check for growth.

A

hemolysis

MHA or TSA

X and V

35C

24H

44
Q

•__________ ATCC 35056 grows around XV-disk only.
•__________ ATCC 7901 grows around V-disk and XV-disk.
• __________ATCC 33940 grows around X-disk and XV-disk.

A

Haemophilus influenzae

Haemophilus parainfluenzae

Haemophilus ducreyi

45
Q

Haemophilus: Laboratory Diagnosis

: XV no hemolysis
: V no hemolysis
: XV with hemolysis
: V with hemolysis
: X only no hemolysis

A

Hi

Hpi

Hh

Hph

Hd

46
Q

Haemophilus: Laboratory Diagnosis
Laboratory Identification

• Alternative method for heme-producing species

A

Porphyrin Test

47
Q

Haemophilus: Laboratory Diagnosis
Laboratory Identification
Porphyrin Test

• Principle: Inoculate isolates on medium with_________ → incubate 35°C, 4 hours → organisms are able to convert ALA into_____________ (intermediates of X factor) → add _______________→ check under UV lignt (Wood lamp, 360nm) for__________color

A

S-aminolevulinic acid (ALA)

porphyrins or porphobilinogen

Kovac reagent (p-dimethylaminobenzaldehyde)

reddish orange color

48
Q

Positive porphyrin reaction

A

reddish orange color

49
Q

CLSI abbreviated test guidelines for ID of commonly isolated bacteria.

  1. GNB, coccobacilli from RT specimens
  2. CS with larger than 1 mm colonies on CHOC
  3. No growth or satellitism on SBA
  4. NEGATIVE PORPHYRIN test
    → identified as
A

H. influenzae

50
Q

Factor X +, V +, Porphyrin-

A

H. influenzae
H. haemolyticus

51
Q

Factor X-, V +, Porphyrin +

A

H. parainfluenzae
H. parahaemolyticus
H. paraphrohaemolyticus
A. segnis

52
Q

Factor X +, V-, Porphyrin-

A

H. ducreyi

53
Q

Factor X-, V-, Porphyrin +

A

A. aphrophilus

54
Q

Factor X +, V +, Porphyrin-

HEMOLYSIS (Horse/ Rabbit)

A

H. influenzae (-)
H. haemolyticus (+)

55
Q

Factor X-, V +, Porphyrin +

Hemolysis (Horse/ Rabbit)

A

H. parainfluenzae
H. parahaemolyticus (+)
H. paraphrohaemolyticus (+)
A. segnis

56
Q

Factor X +, V-, Porphyrin-

Hemolysis

A

H. ducreyi (+/-)

57
Q

Factor X-, V-, Porphyrin +

Hemolysis

A

A. aphrophilus (-)

58
Q

Haemophilus influenzae type b (Hib) vaccination recommended for…

A

children younger than 5 years old

Bacte LEC (51 decks)

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