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HCLD Micro > Fastidious Gram Neg Rods > Flashcards

Fastidious Gram Neg Rods Flashcards

1
Q

HACEK Organisms

A

-Haemophilus
-Aggregatibacter
-Cardiobacterium / Capnocytophage
-Eikenella
-Kingella

-Normal flora of oral cavity
-Need CO2 to grow
-Can be isolated from blood cultures
-Endocarditis

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2
Q

Haemophilus characteristics

A

-Small pleomorphic GNR
-Nonmotile
-Facultative anaerobe
-Ox+
-Cat+
-Comprise 10% of NRF
-Need X (hemin) and V (NAD) Factors
-Satellitism = growth around hemolytic Staph, Strep, or Neisseria colony bc these produce NAD

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3
Q

H. flu virulence factors

A

1) Capsule
2) IgA Protease
3) Fimbriae
4) LPS and OMP

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4
Q

H flu capsule

A

-Six serotypes (a, b, c, d, e, f) based on capsule polysaccharides
-Hib most invasive prior to vaccine
–b capsule consists of ribose, ribitol, PRP
–only subtype to NOT adhere to epis, which is why is goes systemic instead

-children have Ig from their mom until 6 months of age and then are susceptible to infection until ~ 6 years of age

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5
Q

H flu other antigens

A

-IgA protease that breaks down secretory IgA on mucosal surfaces of the resp tract
-Adherence (fimbriae) to epi cells
-LPS blocks sweeping motion or resp cillia

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6
Q

H flu invasive disease

A

-Caused by encapsulated strains
-Septicemia, meningitis, arthritis, epiglottitis, tracheitis, and pneumonia
-Post-vaccine, encapsulated c and f most likely to cause disease
1) Meningitis and bacteremia, mostly in < 6 years of age
–Inhalation->lymph nodes->bloodstream->meninges
2) Epiglottitis -> rapid onset, acute inflammation and edema -> tracheostomy needed to unobstruct airway
–Examination of the larynx can cause spasm that obstructs airway
3) Tracheitis after viral resp infection -> thick secretions after 2-7 days of mild symptoms
4) Septic arthritis - fever, pain, swelling
5) Sepsis - typically in children with no / nonfunctioning spleen

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7
Q

H flu noninvasive disease

A

-Nonencapsulated strains
-Spread via respiratory close proximity
-Conjunctivitis, sinusitis, otitis media
-Can cause pneumonia in older patients and meningitis in immunocompromised
-COPD patients prone to infection

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8
Q

H aegyptius

A

Similar to H flu but causes pinkeye

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9
Q

H influenzae aegyptius

A

Brazilian purpuric fever (BPF)
-conjunctivitis, high fever, vomiting, rash, septicemia, shock, death
-70% mortality rate w/in 48 hours

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10
Q

H flu invasive disease treatment

A

-AmpR due to plasmid
-3rd gen ceph (cefotaxime, ceftriaxone) treatment of choice
-Antibiotics cause the bacteria to lyse and secrete LPS
-“Violent immune response” that destroys neurons
-Give steroids after antibiotics

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11
Q

H ducreyi

A

-Strict human pathogen
-Chancroid Genital Ulcer Disease
-Infects mucosal epi, genital and nongential skin, regional lymph nodes
-“soft chancre”
-4-14 day incubation period then lesion with irregular edge, pus, and draining lymph nodes (buboes)
-treat w/ erythromycin, azithro, ceftriaxone, or cipro

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12
Q

H paraflu

A

Rare endocarditis 1 month after dental procedure

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13
Q

Haemophilus culture

A

1) Choc
2) Choc w/ bacitracin if resp specimen
3) Choc w/ IsoVitaleX if H aegyptius or H ducreyi
–add Vanc for H ducreyi bc resistant
–hold 4-7 days

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14
Q

Haemophilus ID

A

1) X/V factor requirements
–H flu / H haemo +/+
–H parai / H paraheamo =/+
–A. aphro =/=
–H ducreyi +/=

2) Porphyrin rxn
–convert ALA into porphyrins
–add Kovacs
–red / UV light = +

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15
Q

Aggregatibacter aphrophilus

A

-endocarditits
-found in dental plaque
-fever, heart murmur, CHF, embolism
-convex, granular colonies, yellow, opaque at center

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16
Q

Aggregatibacter actinomycetomcomitans

A

-Infection through animal bites (cattle, sheep, pig, horse)
-six serotypes
-peridontitis
–destruction of alveolar bone
-collagenase & leukotoxin
-colonies are star shaped after 48 hours
-X/V =/=
-Urease =
-3rd gen ceph, quinolones, chloram, tet

17
Q

Cardiobacterium hominis

A

-pleomorphic, nonmotile, fastidious, GNR
-normal flora of mouth, nose, throat, GI tract
-Endocarditis after dental procedures
-large vegetations and no fever
-most likely to infect aortic valve
-gram stain looks like rosettes
-colonies pit agar

18
Q

Eikenella corrodens

A

-mouth and gut flora
-Infectious due to trauma like bites or hitting someone in the mouth
-opportunistic
-meningitis, empyema, pneumonia, osteomyelitis, arthritis, postop tissue infection, IV drug user cellulitis (licking needle before use)
-ox+, nonmotile, cat=, yellow
-Pit agar fuzzy zone around them
-smells like bleach

19
Q

Kingella

A

-GVCB w/ squared ends in pairs and chains (resist decolorization)
-nonmotile, ox+, cat=
-Colonize upper resp tract - tonsils
-Can grow on MTM -> use cat to differentiate between Kingella and Neisseria
-K. kingea spready corroding colony OR smooth convex B-hemo colony
-Osteoarthritis in children < 3
-Endocarditis in older children / adults

20
Q

Capnocytophaga

A

-Normal oral flora
-Septicemia in neutropenic patients, endocarditis, juevenile periodontitis
-Fastidous, facultative anaerobe, thin fusiform GNR
-Gliding motility
-Yellow adherent colonies with moist spreading

_C canimorsus / C cyodegmi -> life threatening after dog or cat bite

-Resistant to aminoglycosides

21
Q

Pasteurella

A

-Zoonotic -> animal bites especially cats
–do not close wound
-Cutaneous infection can become systemic
–spread to joints, bones
-GNCB w/ bipolar staining, nonmotile, facultative anaerobic
-Cat+ / ox+
-Colonies become mucoid (capsule) w/ brown/green halo
-NOT facultative intracellular
-treat with pen or doxy

22
Q

Brucella

A

-cat B select agent
-Undulant Fever
-High risk - vets, hunters, lab workers, meat packers
-Acquired through aerosol, percutaneous, or oral route
–no lesion
–spreads to mphages, invades blood and organs
–direct contact with animals or milk products
-Rare sex or breast feeding transmission

23
Q

Brucella stages

A

1) Acute
–fever, malaise, headache, myalgia, back pain
–w/in 8 weeks of exposure
2) Subchronic
–undulating fevers (normal in morning, high at night), arthritis, testes inflammation
–< 1 year after exposure
3) Chronic
–> 1 year after exposure
–depression, arthritis, chronic fatigue

24
Q

Brucella characteristics

A

-small GNR
-aerobic
-nonmotile
-unencapsulated
-smooth, raised, translucent colonies on BAP
-obligate/facultative intracellular
-Ox+ / cat+ / urease +
- H2S+ using lead acetate
-BSL3!!!!!!
-2% of cases are from lab (most common lab acquired infection)

25
Q

Brucella differentiation

A

CO2/H2S/Growth in Thionin/Growth in Basic Fuchsin

B. melitensis: =/=/+/+
B. abortus: +/+/=/+
B. canis: =/=/+/=
B. suis: =/=/+/=

26
Q

Francisella tularensis

A

-Four subtypes
-Opportunistic
-Zoonotic
-Rabbit Fever (also Lemming Fever, Water Rat Trappers’ Disease)
-Ingestion, inhalation, tick/fly bite, contact w/ infected tissue
-only need 10!!!! organisms to cause disease
–many labs won’t culture it intentionally

27
Q

Francisella disease

A

1) Ulceroglandular
–ulcer w/ black base at site of inoculation -> painful swelling of regional lymph nodes (can drain pus)
2) Pneumonic
3) Glandular
4) Oropharyngeal
5) Occuloglandular
6) Typhoidal

28
Q

Francisella characteristics

A

-nonmotile
-GNR/GNCB
-Strict aerobe
-Facultative intracellular
-Initial growth on BAP but needs supplementation after passage (cysteine, cystine, thiosulfate)
-Can grow on Choc, MTM, BCYE
-48 hours before colonies seen
-gray-white, smooth, raised colonies
-Ox= / ur= / X/V =/-
-BSL3!!!!!

29
Q

Bordetella characteristics

A

-Nonmotile
-GNCB
-Hemolytic
-Obligate aerobic
-Nonfermenters
-Cat+
-Urease= (except for B. parapertussis)

30
Q

B. pertussis culture

A

-Very fastidious -> requires special media
-DO NOT collect on cotton swab
-Transport to Amies w/ charcoal (24 hour stability) or Regen-Lowe 1/2 strength (48 hour stability at 35C)
-Bordet-Gengou potato infusion agar w/ glycerol & horse or sheep blood
-Regan-Lowe: charcoal agar w/ 10% horse blood & 40mg/L cephalexin
-Incubate 35C in AMBIENT air for >7 days
-Smooth, glistening silver droplet colonies
-DFA stain of specimen

31
Q

B pertussis virulence

A

1) Filamentous hemaglutinin (FHA) outer membrane protein
–attachment pili
2) Pertussis toxin (PT)
–Exotoxin increases cAMP
–modification of host proteins by ADP-ribosyl transferase
–stops signal transduction
–increased sensitivity to histamine
–increased insulin resistance
–increased number of lymphocytes in blood
3) Adenylate cyclase toxin
–increases cAMP
–inhibits immune cells by weakening them
4) Tracheal cytotoxin
–inhibits DNA synthesis
–ciliostasis
–kills ciliated epi cells
5) Capsule
6) Beta-lactamase

32
Q

B pertussis disease

A

Whooping cough
1) Catarrhal phase
–1-2 weeks
–cold symptoms - runny nose, sneezing, cough, low-grade fever
2) Paroxysmal phase
–Bursts of nonproductive cough
–can last > 1 month
3) Convalescent stage

33
Q

B bronchiseptica

A

-Kennel cough in dogs
-Bronchitis in humans

34
Q

Bordetella diagnositics

A

Growth on BAP / Urease / Motility / Oxidase
B. pertussis: =/=/=/+
B. bronchioseptica: +/+/+/=
B. parapertussis: +/+/=/+

35
Q

Legionella

A

1) Legionnaire’s Disease
-High fever and severe pneumonia
-2% of all CA-pneumonia
-low heart rate
-rhabdomyolysis
-elevated liver enzyme
2) Pontiac Fever
-headache, muscle aches, fatigue, fever, chills
-duration of one week then self-resolves

36
Q

Legionella characeristics

A

-slow-growing GNR
-facultative intracellular
-NG on BAP, MAC
-Needs hemin supplements (L-cysteine)
-Treat specimen with KCl-HCl before inoculation
-Feeley-Gorman iron cysteine agar
–brown pigment, incubate in 2.5% CO2
-BCYE w/ alpha-ketoglutarate
–use a combo of nonselective and semiselective BCYE
–semiselective if polymyxin B, anisomycin, and Van or Cefamandole
-Incubate 3-5 days 35C in ambient air
–incubate aerobically
-grey/white or blue/green convex glistening colonies
–center is “ground glass”
-confirm with DFA
-Urine antigen test must be confirmed with culture

37
Q

Legionella treatment

A

Macrolides
Quinolones

HCLD Micro (13 decks)

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