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Haemophilus and Other Fastidious Flashcards

(61 cards)

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1
Q

Pasteurellaceae (Pasteurella and Haemophilus)

A
  • gram-negative coccobacilli
  • non-motile, aerobic to facultative
  • reduce nitrate to nitrite
  • oxidase + and catalase +
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2
Q
  • obligate parasites of mucous membranes
  • require X and V factor
  • grow on chocolate agar
  • part of normal flora of upper respiratory tract
A

Haemophilus

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3
Q

Haemophilus means _______

A

blood loving

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4
Q

X factor

A

hemin (hematin)

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5
Q

V factor

A

nicotinamide-adenine dinucleotide (NAD)

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6
Q

only require V factor

A

para- Haemophilus species

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7
Q

Hemolysis on 5% horse or rabbit blood agar

A
  • H. hemolyticus and H. ducreyi

- can’t use SBA because it doesn’t have V factor

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8
Q

Growth patterns

A
  • satellitism around S. aureus (and species that release V factor)
  • exceptions: H. aphrophilus and H. ducreyi
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9
Q

H. influenzae

A
  • often a secondary infection (was in a pandemic)

- can test for beta-lactamase

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10
Q

H. influenzae (virulence factors)

A
  • capsule (A-F types)
  • IgA protease
  • outer membrane proteins and lipopolysaccharide (LPS)
  • adherence (pili)
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11
Q

H. influenzae capsule

A
  • antiphagocytic molecules (ribose, ribitol, and phosphate)

- nontypable strains cause localized infections (pneumonia, otitis media, sinusitis)

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12
Q

Haemophilus influenzae serotype b (Hib)

A
  • primarily in children
  • bacteremia can spread to tissues
  • # 1 cause of meningitis in unvaccinated children
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13
Q

Clinical disease of Hib

A
  • meningitis (children under 6)
  • epiglottitis (can cause airway obstruction)
  • bacterial tracheitis
  • cellulitis, pharyngitis, pneumonia
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14
Q

Non-encapsulated H. influenzae (diseases)

A

otitis media, bronchitis, sinusitis, pneumonia

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15
Q

H. aegyptius is the causative agent of _________

A

pinkeye (conjunctivitis)

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16
Q

H. aegyptius (clinical infections)

A
  • conjunctivitis

- Brazilian purpuric fever (BPF): has a high mortality rate

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17
Q

H. ducreyi

A
  • sexually transmitted infection
  • chancroid (soft chancre)
  • incubation up to 14 days
  • painful legion, enlarged lymph nodes, buboes
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18
Q

H. parainfluenzae (clinical infections)

A

endocarditis

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19
Q

H. aphrophilus/Aggregatibacter aphrophilus (clinical infections)

A

bite wound infections, endocarditis

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20
Q

Culturing Haemophilus

A
  • must plate immediately, they die rapidly
  • BAP for those that don’t require V factor
  • DON’T GROW ON MAC
  • transluscent, moist, smooth colonies
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21
Q

Culturing H. influenzae

A

chocolate agar with bacitracin (to inhibit other respiratory flora)

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22
Q

Culturing H. ducreyi

A
  • extremely fastidious (7 days to grow)

- “school of fish” morphology on gram stain

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23
Q

Lab ID of Haemophilus

A
  • place colonies in nutrient broth, then streak Mueller-Hinton agar plate, use X and V strips and incubate
  • Quad plate to ID factors needed (X, V, X & V, horse blood)
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24
Q

Porphyrin test

A
  • differentiates species that require X factor
  • Positive: organism converts delta-aminolevulinic acid to porphyrin (intermediate of X factor)
  • positive result means organism doesn’t need X factor
  • positive result on Wood lamp fluoresces
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25
H. influenzae negative identification
- from respiratory or CSF specimen - gram-neg. bacilli that have colonies >1mm on chocolate - no growth on SBA, except satellitism - negative porphyrin
26
Haemophilus that require both X and V factors
H. influenzae, H. ageyptius, H. hemolyticus
27
Haemophilus that requires only X factor
H. ducreyi
28
HACEK
- Haemophilus (Aggregatibacter aphrophilus) - Actinobacillus/Aggregatibacter actinomycetemcomitans - Cardiobacterium hominis - Eikenella corrodens - Kingella species
29
HACEK (general characteristics)
- none grow on Mac - requires CO2 for growth - usual flora of oral cavity (human bite wounds) - significant cause of endocarditis
30
- requires V factor | - associated with dental plaque
A. aphrophilus
31
- animal pathogen usually; gram-negative coccobacilli - distinctive star in center of colony - normal oral flora (causes peridontitis) - catalase +, oxidase variable - urease, indole, esculin, citrate -
Aggregatibacter actinomycetemcomitans
32
- non-motile, sometimes gram variable - "rosette" morphology - normal flora of nose, mouth and throat - may cause pitting on agar plates
Cardiobacterium hominis
33
Cardiobacterium hominis
- infects aortic valve | - causes endocarditis
34
- capnophilic, requires X factor - bleach-like odor - pitting in the agar - no growth on Mac or EMB
Eikenella corrodens
35
Eikenella (clinical infections)
- "clenched fist" bacteria (human bite/fight wounds) - pneumonia, meningitis, osteomyelitis, arthritis - cellulitis (when needles are licked clean - drug users) - endocarditis (least of HACEK group)
36
- non-motile, but may twitch - oxidase +, catalase - - found in upper respiratory tract
Kingella species
37
Kingella kingae
- grows on MTM, resembles gonhorrea - may pit on agar - catalase -, oxidase - - affects bones and joints of children
38
Kingella dentrificans
- catalase -, superoxol - | - differentiates it from Neisseria
39
Capnocytophaga
- resemble HACEK - gram-negative, fusiform, capnophilic - have gliding motility - dental problems, septicemia (if gets into blood)
40
Pasteurella multocida
- five serogroups (A-F) - bipolar staining (safety-pin appearance) - grow on BAP and Chocolate, no growth on MAC - zoonosis (dog or cat bites/scratches) - non-motile, catalase +, oxidase + - weak acid production
41
Brucella
- strict aerobes, non-spore forming, non-encapsulated - fine sand morphology (Brucella melitensis) - oxidase +, catalase +, H2S production, UREASE + - blood and bone marrow specimens typically
42
Brucella (clinical infections)
- Brucellosis and UNDULANT FEVER (long infection) - systemic infection with multi-organ involvement - zoonotic (animal contact, animal products) - infection via penetration of ocular or oral mucosa - lab-acquired infection
43
undulant fever
fever recurring at regular intervals
44
Francisella
- require CYSTEINE for growth, grow on CAP, MTM, BCYE - strict aerobes, don't grow on MAC, SBA - zoonotic infections - category A select agent
45
organism that cause zoonotic infection
Pasteurella multocida, Brucella, Francisella
46
F. tularensis
- type A - transmitted by rabbits, sheep, ticks - rabbit fever - tularemia
47
Other Francisella species
F. holarctica (type B), F. mediasiatica, F. novocida
48
Legionella
- acquired through inhalation (not zoonotic) - isolation on special media, identified by serologic testing - community-acquried pneumonia, nosocomial infections - environmental water sources, air conditioning systems
49
L. pneumophilia
- primary Legionella pathogen (16 serogroups) - virulence: ability to invade and survive in macrophages - results from inhalation of aerosols (not person-to-person) - Legionnaires' disease - Pontiac fever
50
Legionnaires' disease
- epidemic outbreaks usually from air conditioners - nosocomial infections (respiratory equipment and aerosol) - community-acquired pneumonia - cough, fever, headache, myalgia, dissemination via circulatory system - can have high mortality rate; hard to ID
51
Pontiac fever
- inhalation of Legionella - no pulmonary involvement - mild form of Legionnaires disease
52
Legionella sources
- aquatic sources - air conditioning systems - survive at large range of temps - adherence to pipes, rubber, plastics - can live intracellularly in protozoa
53
Legionella specimens
predominantly respiratory specimens
54
Legionella (characteristics)
- difficult to ID - thin, weakly staining gram-negative rods; small colonies - blue-green colonies, ground-glass look - found within macrophages and neutrophils - aerobic, require Cysteine for growth - grow well on BCYE
55
Bordetella (major pathogens)
Bordetella pertussis and Bordetella parapertussis
56
Bordetella (minor pathogen)
Bordetella bronchiseptica - opportunistic, pneumonia and wound infections
57
Bordetella (virulence)
Pertussis toxin - interferes with signal transduction
58
Bordetella (infection)
- acquired from breathing in aerosols (adheres to cells) - highly contagious, vaccine available - causes Whooping cough
59
Whooping cough
- presents with flu-like symptoms - highly contagious - severe repetitious coughing - can be followed by vomitting - serious in young children - causes hypoxia
60
Culturing Bordetella
- specimens from nasopharynx - MUST USE calcium alginate or Dacron swab - use Regan-Lowe transport medium or Bordet-Gengou potato infusion agar - incubates for 7 days
61
Bordetella (characteristics)
- gram-negative rod - obligate aerobe - smooth silver pinpoint colonies resembling mercury droplets

Microbiology (26 decks)

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