Gram - Part B Flashcards
This organism was formerly called the Koch-Weeks bacillus and it is associated with highly communicable form of conjunctivitis (pinkeye) in children
HAEMOPHILUS AEGYPTIUS
the causative agent of Brazilian purpuric fever
BIOTYPE III
Haemophilus aegyptius is closely related to H influenzae
A disease of children characterized by fever, purpura, shock, and death
H influenzae biotype III
Isolates are often encountered as causes of infective endocarditis and pneumonia
Aggregatibacter aphrophilus
AGGREGATIBACTER APHROPHILUS
These organisms are present in the oral cavity as part of the normal
respiratory microbiota along with other members of the HACEK
Causes chancroid (so chancre), a sexually transmitted disease
HAEMOPHILUS DUCREYI
Consists of a ragged ulcer on the genitalia, with marked swelling and tenderness.
Chancroid
Requires X factor but not V factor.
H ducreyi
It is grown best from scrapings of the ulcer base that are inoculated onto
chocolate agar containing 1% IsoVitaleX and vancomycin, 3 μg/mL; the agar is
incubated in 10% CO2 at 33°C.
H ducreyi
Are more sensitive than culture in H ducreyi
Nucleic acid amplification methods
1 g of azithromycin taken orally in H ducreyi infection
- 1 g of azithromycin taken orally
- intramuscular ceftriaxone,
- oral ciprofloxacin, or oral erythromycin; healing results in 2 weeks.
Most markedly hemolytic organism of the group in vitro; it occurs both in the normal nasopharynx and in association with rare upper respiratory tract infections of moderate severity in childhood
H haemolyticus
Resembles H influenzae and is a normal inhabitant of the human respiratory tract; it has been encountered occasionally in
infective endocarditis and in urethritis.
H parainfluenzae
The organisms are minute, gram-negative coccobacilli resembling H influenzae. A capsule is present and is nonmotile
BORDETELLA PERTUSSIS
A charcoal-containing medium supplemented with horse blood, cephalexin, and amphotericin B (Regan-Lowe) is preferable because of the longer shelf life culture is used for
BORDETELLA PERTUSSIS
The small, faintly staining gram-negative rods of BORDETELLA PERTUSSIS are identified by
Immunofluorecence staining
- strict aerobe
- oxidase and catalase positive
- nitrate, citrate, and urea negative
- does not require X and V factors on subculture
BORDETELLA PERTUSSIS
Acts as a central regulator of virulence genes
One locus on the B pertussis chromosome. This locus has 2 Bordetella operons, bvgA and bvgS
- Responds to environmental signal
2. Is a transcriptional activator of the virulence genes.
- BvgS
2. BvgA
A large surface protein, and fimbriae
(surface appendages) mediate adhesion to ciliated epithelial cells and are essential for tracheal colonization
Filamentous hemagglutinin
Promotes lymphocytosis, sensitization to histamine, and enhanced insulin secretion by means of adenosine diphosphate–ribosylating activity
that disrupts function of signal transduction in many cell types
Pertussis toxin (a classic A/B structure toxin)
Is an important virulence factor that inhibits phagocyte function
Adenylate cyclase toxin (ACT
Not regulated by bvg and kills respiratory
epithelial cells in vitro.
tracheal cytotoxin
After an incubation period of about 2 weeks, the _______ develops, with mild coughing and sneezing in B. pertussis. During this stage, large numbers of organisms are sprayed in drop- lets, and
the patient is highly infectious but not very ill.
“catarrhal stage”
During this stage , the cough develops its explosive character and the characteristic “whoop” upon inhalation. This leads to rapid exhaustion and may be associated with vomiting, cyanosis, and convulsions.
“paroxysmal” stage
Is a common cause of prolonged (4–6 weeks) cough in adults with convalescence is slow
B pertussis
Preferred specimen in indentification of B pertussis
Nasopharyngeal swabs or NP aspirates
Swabs should be either_____ and not calcium alginate, as it inhibits the polymerase chain reaction (PCR), nor cotton, as cotton kills the organisms.
dacron or rayon tipped
Can be used to examine nasopharyngeal swab specimens. However, false-positive and false-negative results may occur. But is most useful in identifying B pertussis after culture on solid media.
Fluorescent antibody (FA) reagent
Production of IgA, IgG, and IgM antibodies occurs after exposure to B pertussis and these antibodies can be detected
enzyme immunoassays
Are of little diagnostic help acutely because a rise in agglutinating or precipitating antibodies does not occur until the third week of illness.
Serologic tests
Administration of this drug during the catarrhal stage of disease promotes elimination of the organisms and may have prophylactic value.
erythromycin
may prevent anoxic damage to the
brain during B pertussis infection
Oxygeb inhalation and sedation
This organism may produce a disease similar to whooping cough, but it is generally less severe. The infection is often subclinical.
BORDETELLA PARAPERTUSSIS
Grows more rapidly than typical B pertussis and produces larger colonies. It also grows on blood agar.
BORDETELLA PARAPERTUSSIS
Is a small, gram-negative bacillus that inhabits the respiratory tracts of canines, in which it may cause “kennel cough”
and pneumonitis
BORDETELLA BRONCHISEPTICA
It causes snuffles in rabbits and atrophic rhinitis in swine. It is infrequently responsible for chronic respiratory tract infections in humans, primarily in individuals with underlying diseases.
BORDETELLA BRONCHISEPTICA
Has a silent copy of the pertussis toxin gene. This organism possesses a β-lactamase that renders it resistant to
penicillins and cephalosporins.
BORDETELLA BRONCHISEPTICA
They are gram negative but often stain irregularly, and they are aerobic, nonmotile, and nonspore forming
Brucellae
Small, convex, smooth colonies appear on enriched media in 2–5 days.
Brucellae
Fresh specimens from animal or human sources are usually inoculated on
trypticase-soy agar or blood culture media.
Brucillae
Use carbohydrates but produce neither acid nor gas in amounts sufficient for classiffication.
• Catalase and oxidase are produced by the four species that infect humans.
• Hydrogen sulfide is produced by many strains, and nitrates are reduced to nitrites.
Brucellae
Are moderately sensitive to heat and acidity. They are killed in milk by pasteurization.
Brucellae
Is a particularly common vehicle for Brucellae infection
Cheese made from unpasteurized goats’ milk
Is a particularly common vehicle for Brucellae infection
Cheese made from unpasteurized goats’ milk
Occasionally occurs in Brucellae infection
- Granulomatous nodules
- Osteomyelitis
- Meningitis
- cholecystitis
The main histologic reaction in brucellosis
Proliferation of mononuclear cells, exudation of fibrin, coagulation necrosis, and fibrosis
Specifically designed to culture Brucella species bacteria.
Brucella agar
Treatment for Brucellae infection
tetracyclines, rifampin,
trimethoprim–sulfamethoxazole, aminoglycosides, and some
quinolones.
Treatment In patients with endocarditis or evidence of neurological disease with Brucellosis
triple therapy with doxycycline, rifampin, and an aminoglycoside is
suggested
