Section 1: Aerobic Gram Negative Coccobacili

Question 1

What are the characteristics of Haemophilus sp.

Answer 1

Small

Normal flora of the upper respiratory tract

Question 2

What are the growth requirements of Haemophilus

Answer 2

Heme, a building block of hemoglobin
X factor-component ofblood called hemin
V factor-either NAD or NADP
In lab Haemophilus is grown on chocolate blood agar

Question 3

What are the two groups Haemophilus influenzae is split into

Answer 3

1: Encapsulated or typeable strains
2: Non encapsulated or nontypeable strains

Question 4

What is the epidemiology of Haemophilus influenzae

Answer 4

Transmitted in respiratory secretions.
Usually non encapsulated strains are part of the normal flora
• However, a minority (3-7%) of healthy individuals harbor Hib in the upper respiratory tract

Question 5

What is the pathogenesis of Haemophilus influenzae

Answer 5

Meningitis
Epiglottitis
Pneumonia

Question 6

What is meningitis

Answer 6

Leading cause of acute meningitis in children (until widespread vaccination program began in 1985)
• Regional lymph nodes and meninges are infected • Bloodstream can be infected = bacteremia
• Serious neurologic sequelae (abnormal condition following or related to a previous disease) frequently develop and persist after recovery from meningitis

Question 7

What is epiglottitis

Answer 7

Infection of the epiglottis characterized by swelling
• Pediatric illness which can be life-threatening emergency
• Symptoms include, rapid progression, high fever, drooling, inspiratory strider, and difficulty breathing when supine
• Since the advent of the Hib vaccine the disease is seldom seen

Question 8

What is Pneumonia

Answer 8

Seen in adult debilitated, imrnunocompromised patients

Question 9

How is Haemophilus influenzae diagnosed

Answer 9

Microscopy
Serotyping
Culture on chocolate blood agar 
Agglutination testing 
Culture on blood agar with Staphylococcus aureus

Question 10

How is Haemophilus influenzae prevented

Answer 10

Until 6 mos. of age infant is protected by maternal antibodies
In 1985 first Hib conjugate vaccines licensed for use
• All children should have vaccine approved for infants at 2 mos o Children older than 60 mos. and adults do not need to be vaccinated

Question 11

What is Haemophilus ducreyi

Answer 11

Causative agent of the sexually transmitted infection (STI), chancroid
-After an incubation period of one day to two weeks, begins with a small bump on the genitalia that becomes an ulcer within a day of its appearance

Question 12

How is Haemophilus ducreyi diagnosed

Answer 12

Obtain smear from genital ulcers and culture on chocolate blood agar
Rule out other STis

Question 13

What is often seen in the inguinal regions of patients with Haemophilus ducreyi

Answer 13

Patients often have adenopathy (swollen lymph nodes) in the inguinal area

Question 14

What is the characteristic of the Haemophilus ducreyi ulcer

Answer 14

The ulcer characteristically:
• is painful
• has irregular or ragged borders
• is soft and has a base that is covered with a yellowish-grey material
Men typically have 1 ulcer, while females have multiple ulcers

Question 15

What is Haemophilus vaginalis

Answer 15

aka Gardnerella vaginalis
• Part of normal vaginal flora
• Sometimes causes mild infection

Question 16

How is Haemophilus vaginalis diagnosed

Answer 16

Gram stain reveals “clue cells”
• Identified as numerous stippled or granulated epithelial cells
• Characteristic of H. vaginalis infection

Question 17

What is Bordetella pertussis

Answer 17

Capsule

• Three serotype based on capsular antigens have been identified
• Nutritionally fastidious, cultivated on rich media supplemented with blood
• Do not require X and V factors
• Causative agent of pertussis (whooping cough)

Question 18

What are the virulence factors of Bordetella pertussis

Answer 18

Pertussis Toxin 
Filamentous Hemagglutinin
extracellular adenylate cyclase 
endotoxin
Strain reversion

Question 19

What does the buildup of cAMP from Bordetella pertussis lead to

Answer 19

Increased insulin production, resulting in hypoglycemia
• Increased sensitivity to histamine, resulting in increased capillary permeability, hypotension, and shock
• Inhibition of monocytes migrating into tissue

Question 20

What is Filamentous Hemagglutinin

Answer 20

Large protein that forms filamentous structures on the cell surface that bind to the ciliated host cells allowing colonization of host tissue

Question 21

What is extracellular adenylate cyclase (TOXIN)

Answer 21

B. Pertussis secretes invasive adenylate cyclase which enters host cell and acts locally to reduce phagocytic activity, particularly of neutrophils

Question 22

What is Strain reversion

Answer 22

Transposon mutagenesis can result in a virulent strain (phase I) becoming non-virulent (phase IV)
• Phase N strain can revert (lose the transposon) and become virulent

Question 23

What is the epidemiology of Bordetella pertussis

Answer 23

Found worldwide
-Primarily infects children under 6 mos.
• Droplet transmission
• Incubation period is 7-10 days
-Pertussis once the most common disease of childhood
-Often fatal, particularly in infants

Question 24

What are the pathological stages of Bordetella pertussis

Answer 24

Catarrhal stage

Paroxysmal stage

Question 25

What occurs during the Catarrhal stage of Bordetella pertussis infection

Answer 25

Colonization of the upper respiratory system • Characterized by fever, malaise and coughing • B. pertussis is recovered in large numbers from pharyngeal cultures • If diagnosed in this stage the severity and duration of the disease can be reduced by antimicrobial treatment

Question 26

What occurs during the Paroxysmal stage of Bordetella pertussis infection

Answer 26

-Follows relatively nonspecific symptoms of catarrhal stage | • Begins gradually with prolonged and paroxysmal coughing that ends in a characteristic inspiratory gasp

Question 27

How is Bordetella pertussis diagnosed

Answer 27

Swab nostrils • Culture on selective media (Bordet-Gengou) • Serum agglutination • Fluorescent antibody testing

Question 28

How is Bordetella pertussis prevented

Answer 28

Whole cell vaccine | Acellular vaccin -fewer side effects

Question 29

How are Brucella species named

Answer 29

for the animal they infect

Question 30

What is the epidemiology of Brucella

Answer 30

Human brucellosis is a true zoonosis in that all infections are acquired from animals. - Brucella penetrates the skin and mucosa o In animals the microbe typically affects the reproductive organs and is contracted by humans via contaminated milk - Brucellosis is rare in the United States, 100 to 200 cases occur each year. - Brucellosis can be very common in countries where animal disease control programs have not reduced the amount of disease among animals

Question 31

What is the pathogenesis of Brucella

Answer 31

- Microbes spread via lymphatic system and multiply in phagocytes (obligate intracellular) - Cause lesions in various organs including: liver, spleen, bone marrow, kidney

Question 32

What are the symptoms of Brucella

Answer 32

fever, unusually severe limb and back pain, marked fatigue

Question 33

How is Brucella diagnosed

Answer 33

Primarily Dependent on cllinical findings | -Grows poorly in culture and may need to be incubated for up to 4 weeks

Question 34

How is Brucella controlled

Answer 34

Immunize cattle sheep and goats. - Live attenuated vaccines have reduced brucellosis in domestic animals - Pasteurization of milk - Protective clothing for those occupationally exposed

Question 35

What are the characteristics of Francisella tularensis

Answer 35

- small - Gram negative - Pleomorphic= rod, coccobacilli, filament-like - Non-motile - Very thin capsule composed of lipids - Pathogenic strains possess capsule, loss of or lack of capsule is associated with decreased virulence - Causative agent of tularemia (aka-glandular fever, rabbit fever, tick fever, and deer fly fever) •

Question 36

What are the 2 strains of Francisella tu/arensis

Answer 36

Type A strain= Francisella tularensis var tularensis causes tick-borne tularemia in rabbits, and produces classic disease in human beings -Type B strain = found predominantly in Europe and Asia, rarely leads to fatal disease

Question 37

What is the epidemiology of Francisella tu/arensis

Answer 37

-Disease of mammals, fish, birds, and invertebrates -Primary vector is infected ticks, sometimes deer flies -Humans are infected by • Direct contact with animal (hunters) • Bite from infected tick or fly • Contaminated food or water

Question 38

What is the pathology of Francisella tu/arensis

Answer 38

- Initial symptoms oftularemia develop after 3-5 day incubation period - Fever, chills, malaise, fatigue

Question 39

How many microbes can cause Francisella tu/arensis

Answer 39

Highly infectious, as few as 10-50 microbes can cause disease

Question 40

What are the subtypes of Tularemia

Answer 40

Ulceroglandular tularemia Pneumonic tularemia Oculoglandular tularemia Typhoidal tularemia

Question 41

How is Francisella tu/arensis diagnosed

Answer 41

- Clinical history - Isolation in culture-must be grown on chocolate agar (sometimes blood agar). Requires incubation times of 1-2 weeks - Agglutination tests - Fluorescent antibody test

Question 42

How is Francisella tu/arensis prevented

Answer 42

-Avoid reservoirs and vectors of infection (rabbits, ticks, flies) -Wear gloves when processing animals -Prompt removal of ticks-F. tularensis present in feces, not saliva. Tick must feed for prolonged period to transmit infection - Live attenuated vaccine is available • Treatment • Not completely effective in preventing disease, but can lessen severity of the disease • Recommended for people at a significantly increased risk of exposure