Exam 1 Study - GPC Pathogenesis

Question 1

Streptococcus agalactiae
Prevention
• In an effort to prevent neonatal disease:

Answer 1

All pregnant women to be screened for colonization at 36 to 37
weeks of gestation
• Chemoprophylaxis should be used for all women who are either colonized or at high risk (previously given birth to an infant with disease; or risk factors for disease)
• Intrapartum temperature of at least 38⁰C
• Membrane rupture at least 18 hours before delivery
• Vaginal or rectal culture positive

Question 2

Streptococcus pneumoniae Virulence Factors

Answer 2

Protein adhesions:
• Ability to colonize oropharynx Pneumolysin:
• Creates pores in epithelial and phagocytic cells thus allowing for spread into normally sterile tissue
Capsule:
• Avoid phagocytes
• Loss of capsule makes the microbe avirulent

Question 3

Streptococcus pneumoniae Infection : Pneumonia

Answer 3

Causes 25-60% of all pneumonia cases
• Characterized by sudden onset of chills, fever, chest pain (pain on inspiration), and cough
• Pneumonia may be complicated by a pleural fluid effusion (empyema)
• Mortality rate of ~5%

Question 4

Streptococcus pneumoniae Infection : Otitis media

Answer 4

Inflammation of the middle ear
• 75% of children experience at least one episode of otitis media by their 3rd birthday
• Almost half of these children will have three or more ear infections during their first 3 years
• Estimated medical costs and lost wages because of otitis media:
$5 billion a year in the United States

Question 5

Streptococcus pneumoniae Illness prevention

Answer 5

Vaccine available
• PPSV23 = 23-valent pneumococcal capsular polysaccharide vaccine for children older than 2 years and adults
• Provides long-lived immunity
• Less effective in some high risk populations (e.g., immunosuppressed and elderly)
• PCV-13 = 13-valent conjugated pneumococcal vaccine for infants
younger than 2 years of age (adds an additional 6 more than PCV7)

Question 6

Genus that is best desctibed as a catalase-negative, gram-positive coccus that is a facultative anaerobe and that forms chains.

Answer 6

Streptococcus

Question 7

The most frequent agent of nosocomial bacteremia (related to a device) is:

Answer 7

coagulase-negative staphylococci

Question 8

Not only normal flora of humans and animals, this genus of bacteria contains agents of important diseases such as rheumatic fever, glomerulonephritis, and exudative pharyngitis.

Answer 8

Streptococcus

Question 9

The Staphylococcus that is more likely to cause uncomplicated urinary tract infections in non-hospitalized hosts, especially sexually active young women, is:

Answer 9

Staphylococcus saprophyticus

Question 10

What is the function of protein A in the cell wall of Staphylococcus aureus?

Answer 10

Bind the IgG and prevent phagocytosis

Question 11

This disease is an extensive exfoliative dermatitis caused by staphylococcal exfoliative toxin.

Answer 11

Scaled-skin syndrome

Question 12

Infections by this organism are predominantly hospital-acquired, and some predisposing factors include catheterization, medical implantation, and immunosuppressive therapy.

Answer 12

S. epidermidis

Question 13

A young man goes to his physician complaining of large, raised, suppurative abscesses on his neck. The man denies having a fever or the chills. What is the name of the lesions on his neck, and what organism causes this type of lesions?

Answer 13

S. aureus and carbuncles

Question 14

Streptococcus agalactiae is a significant cause of:

Answer 14

Invasive disease in newborns

Question 15

All of the following virulence factors are associated with Staphylococcus aureus EXCEPT:

Answer 15

Endotoxins

Question 16

What are the staphylococcal products that cause diarrhea and vomiting in humans?

Answer 16

Enterotoxins

Question 17

One major virulence factor for Streptococcus pneumoniae is:

Answer 17

Capsular polysaccharide

Question 18

Where are the viridans streptococci constituents of the normal flora?

Answer 18

Upper resp, female genitals, gastro

Question 19

A young, healthy woman was rushed to the hospital with a high fever, hypotension, and shock. She hadn’t been feeling well that day, but her condition progressively worsened throughout the day. She was feeling fine until a couple days after she started menstruating. What condition could this woman be exhibiting?

Answer 19

Toxic shock syndrome