Fastidious Gram-Negative Bacilli Flashcards
members of fastidious gram neg bacilli group (hacek)
- haemophilus spp
- aggregatibacter actinomycetemcomitans
- cardiobacterium hominis
- eikenella corrodens
-kingella spp
fastidious, non motile, capnophilic, and facultatively anaerobic bacteria
haemophilus
haemophilus cannot grow on ____
pure blood agars
haemophilus is both ____ and ____ positive
catalase and oxidase positive
haemophilus is both catalase and oxidase positive except for
haemophilus segnis
haemophilus growth factors
X and V factors, porphyrin
x factor include
hemin
V factors include
nicotinamide, adenine dinucleotide or NAD
Haemophilus spp. that are V factor dependent do not grow on ___
SBA
Clinical laboratories use __ for the recovery of Haemophilus
chocolate (CHOC) agar
A phenomenon that helps in the recognition of
Haemophilus spp. that require V factor is?
satellitism
a strictly human pathogen, is the causative agent
of chancroid, a highly communicable sexually transmitted genital ulcer disease (GUD).
H. Ducreyi
for h.ducreyi _____ should be used to collect
material from the base of the ulcer.
Swab premoistened with sterile phosphate buffered saline
___ on selective media at the bedside is preferred instead of using transport media.
Direct plating
Are susceptible to drying
Haemophilus spp.
.When attempting to isolate H. influenzae, CHOC agar is a commonly used medium incubated between __ and ___
33° and 37°
When attempting to isolate H. influenzae, CHOC agar is a commonly used medium in an atmosphere of
5% to 10% carbon dioxide (CO2)
It has been shown that CHOC agar supplemented with _____ is an excellent medium for the isolation of Haemophilus spp. from respiratory specimens.
Bacitracin (300mg/L)
for heamophilus spp growth on CHOC agar is usually seen after ___ of incubation
18 to 24hours
H. ducreyi also grows on enriched CHOC medium, or a ____ can be used.
Nairobi biplate
The use of ___ (most H. ducreyi are resistant) in the media helps reduce the growth of commensal biota from genital specimens and improves the detection of H. ducreyi.
Vancomycin
H. ducreyi grows best at
33° C.
H. influenzae on CHOC agar appear
Tannish
Haemophilus spp. sometimes grow on SBA plates around colonies of other bacterial species— a phenomenon known as
Satellitism
An organism is identified as haemophilus influenzae
Because it requires?
both X and V factors.
This organism requires V factor only and is identified as
Haemophilus parainfluenzae.
The ___ is an alternative method for differentiating the heme-producing species of Haemophilus
porphyrin test
has been associated with meningitis.
C. hominis
The organisms tend to form rosettes, swellings, long filaments, or sticklike structures in yeast extract.
Cardiobacterium hominis
Gram-stained smear of Cardiobacterium hominis showing typical ___
Rosettes
They tend to resist decolorization on Gram stain
Kingella
require increased CO, for growth and isolation from blood cultures.
Capnocytophaga spp.
Capnocytophaga spp. are thin and often - resembling
Fusiform ( pointed ends)
produce gliding motility on solid surfaces.
Capnocytophaga
On agar Capnocytophaga colonies are often adherent and produce a ___ pigment; they can resemble colonies of E. corrodens.
Yellow- orange pigment
. ferment sucrose, glucose, maltose, and lactose, although triple sugar iron agar (TSIA) may be negative without enrichment.
Capnocytophaga spp
are gram-negative, nonmotile, facultative anaerobic coccobacilli that appear ovoid, filamentous, or as bacilli.
pasteurella spp
safety pin appearance when the poles of the cells are more intensely stained
Pasteurella spp. bipolar staining
These bacteria are catalase and oxidase positive and ferment glucose with weak to moderate acid production without gas.
Pasteurella spp.
All Pasteurella spp. grow on __ and __ agar, producing gravish colonies
SBA and CHOC agar
does not support the growth of most Pasteurella spp.
MAC agar
small gram-negative, aerobic, nonmotile,
unencapsulated bacteria that may appear as coccobacilli or bacilli
Brucellae
Brucellae colonies
smooth raised, and translucent colonies
Brucellae are facultative intracellular pathogens that can reside within
mononuclear phagocytic cells.
can vary in their requirement for CO,. They grow on SBA and CHOC agar and can be isolated on MTM or Martin-Lewis media from contaminated specimens.
Brucella spp.
Brucellae are oxidase and catalase positive and are - urease positive within
2 hours
Because of the aerosol mode of transmission, Brucella spp should be handled under
biosafety level 3 conditions
small, nonmotile, gram-negative bacilli or coccoid bacteria and are strictly aerobic.
Francisella spp.
fastidious and require supplementation with cysteine, cystine, or thiosulfate for growth on successive passage.
Francisella spp.
F. tularensis are negative in what test
oxidase, urease, and satellite or X and V test
F. Tularensis is weakly positive for
Catalase and beta-lactamase
A presumptive identification for brucella can be made by a positive test result in any one of the following assays:
- Direct fluorescent antibody (DNA)
- Immunohistologic staining with monoclonal antibody
- PCR
- Slide agglutination
- Single serology test
fastidious, aerobic, motile, and non-carbohydrate fermenters legionnaires disease and pontiac ferer
Legionella
Specimens for culture and direct examination for Legionella spp commonly include
sputum, bronchoalveolar lavage, and bronchial washings
It is recommended to freeze Legionella spp. specimens at ___ if processing will be delayed for several days.
-70° C
are pleomorphic, weakly staining, gram-negative bacilli that are approximatelv 1 to 2um × 0.5um in size
Legionella spp
Extending the safranin counterstaining time to at least _ can enhance the staining intensity of the organisms
10 minutes
agar that is best for Legionella isolation.
BCYE with 0.1% a-ketoglutaric acid (BCYEo)
BCYEa agar, colonies appear as
rainbow/ grayish white or blue-green, convex, and glistening
Characteristic “ground-glass” colony morphology
Legionella
Legionella has a slow growth which takes
3-5 days
Legionella Requires ___ for primary isolation
L-cysteine
The ___ assay is the most common method employed for serologic diagnosis of legionellosis
indirect fluorescent antibody (IFA) assay
small, gram-negative bacilli or coccobacilli, All are obligate aerobic bacteria, do not grow on ferment carbohydrates
Bordetella
Bordetella grow best at _____
35 -37°C
Bordetella are non motile except for
B. bronchiseptica
constitute the specimen of choice for culture and PCR testing for Bordetella.
Nasopharyngeal aspirates or swabs of Dacron polyester with a nonwire shaft
Transport media that can preserve viability of bordetella for up to 48 hours
casamino acid (1% casein hydrolysate) or amies with charcoal
Isolation methods for bordetella
Bordet-Gengou potato infusion agar
On Bordet-Gengou agar, colonies of B. pertussis and B. parapertussis
Hemolytic
Transport system of B. Pertussis
• Casamino acid (1% casein hydrolysate)
• Amies transport medium with charcoal
• Regan-Lowe transport medium
Most vibrio possess - flagella when grown in broth
Monotrichous or multitrichous flagella
They have been described typically as curved or comma-shaped gram-negative rods, in gram stain
Vibrio
The vibrios are facultatively anaerobic, are catalase and oxidase positive and able to reduce nitrate to nitrite, except for
V. metschnikovii,
All species of vibrios, except for V. cholerae and V. mimicus are ___ or salt-loving
halophilic
stool specimens suspected of containing Vibrio spp. should be collected and transported in
Cary-Blair medium
is not acceptable, because glycerol is toxic to vibrios.
Buftered glycerol saline
for specimens suspected of containing Vibrio spp. Feces is preferable, but rectal swabs are acceptable during the ___ of diarrheal illness.
acute phase of diarrheal illness.
V. cholerae toxin can be detected in stool using an
enzyme-linked immunosorbent assay (ELISA) or a commercially available latex agglutination test
When stool specimens from patients with cholera are examined using dark-field microscopy, the bacilli exhibit characteristic __\
rapid darting or shooting-star motility.
on ___ or ___ vibrios produce medium to large colonies that appear smooth, opaque, and iridescent with a greenish hue.
SBA or (CHOC) agar,
should also be examined for the presence of a- or -hemolysis for vibrio spp
SBA plate
On this agar, the pathogenic vibrios usually grow as nonlactose fermenters (except for __)
MAC agar, (except for V. vulnificus )
Vibrio isolate general susceptibility to the ___ (150mg) and ___,distinguishes them from Aeromonas.
vibriostatic agent 0/129 (150mg) and positive string test
SUCROSE FERMENTERS
(YELLOW COLONIES)
V. CHOLERAE
V. ALGINOLYTICUS
V. METSCHNIKOVII
NON-SUCROSE
FERMENTERS (GREEN
COLONIES)
V. MIMICUS
V. VULNIFICUS
V. PARAHEAMOLYTICUS
V. DAMSELA
vibrio motility test: broth
polar sheated flagella
vibrio motility test: Solid media
peritrichous, unsheathed flagella
VIBRIO CHOLERAE is positive in what test
(+) oxidase, indole, lysine and ornithine
decarboxylase
Stool cultures for Vibrio spp. are plated on the selective medium __ agar
thiosulfate citrate bile salts sucrose (TCBS) agar.
2 biogroups of vibrio cholerae
Classical, el tor
VP Test (Voges-Proskauer): for vibrio cholerae biogroup
• Classical: Negative (-)
• El Tor: Positive (+)
Chicken RBC Agglutination: biotypes of Vibrio cholerae
• Classical: Negative (-)
• El Tor: Positive (+)
Polymyxin B Sensitivity: biotypes of Vibrio cholerae
• Classical: Sensitive (S)
• El Tor: Resistant (R)
It differentiates sucrose-fermenting ( yellow) from the nonsucrose-fermenting- (green)
Thiosulfate Citrate Bite Salts Sucrose Agar (TCBS)
