Gram - Part B

Question 1

This organism was formerly called the Koch-Weeks bacillus and it is associated with highly communicable form of conjunctivitis (pinkeye) in children

Answer 1

HAEMOPHILUS AEGYPTIUS

Question 2

the causative agent of Brazilian purpuric fever

Answer 2

BIOTYPE III

Haemophilus aegyptius is closely related to H influenzae

Question 3

A disease of children characterized by fever, purpura, shock, and death

Answer 3

H influenzae biotype III

Question 4

Isolates are often encountered as causes of infective endocarditis and pneumonia

Answer 4

Aggregatibacter aphrophilus

Question 5

AGGREGATIBACTER APHROPHILUS

Answer 5

These organisms are present in the oral cavity as part of the normal
respiratory microbiota along with other members of the HACEK

Question 6

Causes chancroid (so chancre), a sexually transmitted disease

Answer 6

HAEMOPHILUS DUCREYI

Question 7

Consists of a ragged ulcer on the genitalia, with marked swelling and tenderness.

Answer 7

Chancroid

Question 8

Requires X factor but not V factor.

Answer 8

H ducreyi

Question 9

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.

Answer 9

H ducreyi

Question 10

Are more sensitive than culture in H ducreyi

Answer 10

Nucleic acid amplification methods

Question 11

1 g of azithromycin taken orally in H ducreyi infection

Answer 11

• 1 g of azithromycin taken orally
• intramuscular ceftriaxone,
• oral ciprofloxacin, or oral erythromycin; healing results in 2 weeks.

Question 12

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

Answer 12

H haemolyticus

Question 13

Resembles H influenzae and is a normal inhabitant of the human respiratory tract; it has been encountered occasionally in
infective endocarditis and in urethritis.

Answer 13

H parainfluenzae

Question 14

The organisms are minute, gram-negative coccobacilli resembling H influenzae. A capsule is present and is nonmotile

Answer 14

BORDETELLA PERTUSSIS

Question 15

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

Answer 15

BORDETELLA PERTUSSIS

Question 16

The small, faintly staining gram-negative rods of BORDETELLA PERTUSSIS are identified by

Answer 16

Immunofluorecence staining

Question 17

• strict aerobe
• oxidase and catalase positive
• nitrate, citrate, and urea negative
• does not require X and V factors on subculture

Answer 17

BORDETELLA PERTUSSIS

Question 18

Acts as a central regulator of virulence genes

Answer 18

One locus on the B pertussis chromosome. This locus has 2 Bordetella operons, bvgA and bvgS

Question 19

1. Responds to environmental signal

2. Is a transcriptional activator of the virulence genes.

Answer 19

1. BvgS

2. BvgA

Question 20

A large surface protein, and fimbriae

(surface appendages) mediate adhesion to ciliated epithelial cells and are essential for tracheal colonization

Answer 20

Filamentous hemagglutinin

Question 21

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

Answer 21

Pertussis toxin (a classic A/B structure toxin)

Question 22

Is an important virulence factor that inhibits phagocyte function

Answer 22

Adenylate cyclase toxin (ACT

Question 23

Not regulated by bvg and kills respiratory

epithelial cells in vitro.

Answer 23

tracheal cytotoxin

Question 24

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.

Answer 24

“catarrhal stage”

Question 25

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.

Answer 25

“paroxysmal” stage

Question 26

Is a common cause of prolonged (4–6 weeks) cough in adults with convalescence is slow

Answer 26

B pertussis

Question 27

Preferred specimen in indentification of B pertussis

Answer 27

Nasopharyngeal swabs or NP aspirates

Question 28

Swabs should be either_____ and not calcium alginate, as it inhibits the polymerase chain reaction (PCR), nor cotton, as cotton kills the organisms.

Answer 28

dacron or rayon tipped

Question 29

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.

Answer 29

Fluorescent antibody (FA) reagent

Question 30

Production of IgA, IgG, and IgM antibodies occurs after exposure to B pertussis and these antibodies can be detected

Answer 30

enzyme immunoassays

Question 31

Are of little diagnostic help acutely because a rise in agglutinating or precipitating antibodies does not occur until the third week of illness.

Answer 31

Serologic tests

Question 32

Administration of this drug during the catarrhal stage of disease promotes elimination of the organisms and may have prophylactic value.

Answer 32

erythromycin

Question 33

may prevent anoxic damage to the

brain during B pertussis infection

Answer 33

Oxygeb inhalation and sedation

Question 34

This organism may produce a disease similar to whooping cough, but it is generally less severe. The infection is often subclinical.

Answer 34

BORDETELLA PARAPERTUSSIS

Question 35

Grows more rapidly than typical B pertussis and produces larger colonies. It also grows on blood agar.

Answer 35

BORDETELLA PARAPERTUSSIS

Question 36

Is a small, gram-negative bacillus that inhabits the respiratory tracts of canines, in which it may cause “kennel cough”
and pneumonitis

Answer 36

BORDETELLA BRONCHISEPTICA

Question 37

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.

Answer 37

BORDETELLA BRONCHISEPTICA

Question 38

Has a silent copy of the pertussis toxin gene. This organism possesses a β-lactamase that renders it resistant to
penicillins and cephalosporins.

Answer 38

BORDETELLA BRONCHISEPTICA

Question 39

They are gram negative but often stain irregularly, and they are aerobic, nonmotile, and nonspore forming

Answer 39

Brucellae

Question 40

Small, convex, smooth colonies appear on enriched media in 2–5 days.

Answer 40

Brucellae

Question 41

Fresh specimens from animal or human sources are usually inoculated on
trypticase-soy agar or blood culture media.

Answer 41

Brucillae

Question 42

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.

Answer 42

Brucellae

Question 43

Are moderately sensitive to heat and acidity. They are killed in milk by pasteurization.

Answer 43

Brucellae

Question 44

Is a particularly common vehicle for Brucellae infection

Answer 44

Cheese made from unpasteurized goats’ milk

Question 45

Is a particularly common vehicle for Brucellae infection

Answer 45

Cheese made from unpasteurized goats’ milk

Question 46

Occasionally occurs in Brucellae infection

Answer 46

• Granulomatous nodules
• Osteomyelitis
• Meningitis
• cholecystitis

Question 47

The main histologic reaction in brucellosis

Answer 47

Proliferation of mononuclear cells, exudation of fibrin, coagulation necrosis, and fibrosis

Question 48

Specifically designed to culture Brucella species bacteria.

Answer 48

Brucella agar

Question 49

Treatment for Brucellae infection

Answer 49

tetracyclines, rifampin,
trimethoprim–sulfamethoxazole, aminoglycosides, and some
quinolones.

Question 50

Treatment In patients with endocarditis or evidence of neurological disease with Brucellosis

Answer 50

triple therapy with doxycycline, rifampin, and an aminoglycoside is
suggested