Common Bacterial Pathogens 2

Question 1

Streptococci are _________.

Answer 1

Gram-positive cocci, usually in chains or pairs, that are catalase negative

Question 2

Gram-positive cocci are usually either ______ (catalase +) or __________ (catalase-).

Answer 2

staphylococcus; streptococcus

Question 3

Staphylococci are usually either _______ (coagulase+) or ________ (coagulase-).

Answer 3

aureus; SSNA

Question 4

Group A streptococci are ______.

Answer 4

streptococcus pyogenes

Question 5

Group A typically cause __________.

Answer 5

throat infections, wound infections, and post-strep sequlae

Question 6

What factors allow streptococcus pyogenes to cause pharyngitis?

Answer 6

Adherence proteins (especially M-protein); invasion proteins (such as streptolysin S); anti-phagocytic proteins (M-protein again, because it reduces C3b’s ability to bind by binding to Factor H, a natural anti-opsonin)

Question 7

People recover from strep by ________.

Answer 7

developing antibodies against M proteins

Question 8

Streptolysin O might play a role in rheumatic fever by ________.

Answer 8

damaging the heart valves and exposing sequestered antigens

Question 9

The three most common causes of bacterial endocarditis are _________.

Answer 9

staphylococcus aureus, streptococcus viridans, and coagulase negative staphylococci

Question 10

Gamma hemolysis is __________.

Answer 10

actually non-hemolytic

Question 11

Beta-hemolysis is ____________.

Answer 11

complete clearance of RBCs

Question 12

There are both invasive (___________) and non-invasive (____________) forms of streptococcal infections.

Answer 12

meningitis and septicemia; pneumonia, sinusitis, and bronchitis

Question 13

Streptococcus pneumoniae can become pathogenic by __________.

Answer 13

developing anti-phagocytic capsules

Question 14

In pneumococcal pneumonia, the alveolae will have _________.

Answer 14

exudates due to the inflammatory response

Question 15

Predisposing factors to pneumococcal pneumonia include ___________.

Answer 15

alcoholism, viral infection, and being very young or very old

Question 16

Enterococcus faecium and faecalis are _____________.

Answer 16

normal flora that cause UTIs and GI infections (upon breaching the GI epithelium)

Question 17

Nosocomial infections are _____________.

Answer 17

infections acquired in hospitals

Question 18

Of the Gram-positive rods, the ones that are most associated with human disease are _________.

Answer 18

clostridium

Question 19

Clostridia are _________.

Answer 19

strict anaerobes that form endospores

Question 20

The genus clostridium includes _________.

Answer 20

the agents that cause C. difficile, tetanus, botulism, and gangrene

Question 21

Clostridium difficile causes ___________.

Answer 21

nosocomial diarrhea and (more rarely) pseudomembranous colitis

Question 22

Suspect C. difficile when patients develop diarrhea _________.

Answer 22

after being admitted to the hospital and receiving antibiotics

Question 23

Clostridium tetani often infect sites of local infection because _________.

Answer 23

they need anaerobic sites to grow, and the inflammatory response to an injury can produce such a walled-off site

Question 24

C. tetani toxin blocks __________.

Answer 24

inhibitory neurons of the central nervous system

Question 25

Clostridium botulinum is a __________.

Answer 25

Gram-positive rod that is found in soil and on animals; it can survive the canning process--uncooked food can be lethal, because the toxin blocks the acetylcholine receptor and results in flaccid paralysis

Question 26

The cause of gas gangrene is ____________.

Answer 26

clostridium perfringens

Question 27

C. perfringens kills cells by __________.

Answer 27

secreting alpha toxin, which cleaves phospholipases that then induces apoptosis

Question 28

Enterotoxins are not __________.

Answer 28

endotoxins--they are substances secreted by the cell that damage the host

Question 29

_________ and _________ are Gram-negative rods.

Answer 29

Eschericia coli; pseudomonas aeruginosa

Question 30

ETECs are ____________.

Answer 30

enterotoxogenic bacteria

Question 31

Toxic E. coli do not kill cells, rather, they _________.

Answer 31

disrupt the electrolyte balance of the gut

Question 32

Pseudomonas aeruginosa are everywhere; they typically only become a problem in ____________.

Answer 32

wounds (like traumas, burns, or surgeries) and those with cystic fibrosis

Question 33

Those with cystic fibrosis are usually infected with ______ early in life and _______ later in life.

Answer 33

staphylococcus aureus; pseudomonas aeruginosa, possibly because of P. aeruginosa's resistance to anti-staph antibiotics

Question 34

Neisseria are _________.

Answer 34

Gram-negative diplococci

Question 35

Neisseria gonorrhoeae can fight leukocytes by ________.

Answer 35

using their pili to interfere with neutrophil killing

Question 36

Because neisseria gonorrhoeae infect mucosal surfaces, they __________.

Answer 36

induce an inflammatory response that creates exudate

Question 37

In males, N. gonorrhoeae usually leads to just ________, while in females, _________ often occur.

Answer 37

urethritis (if any symptoms arise); inflammation of the vagina, cervix, and fallopian tubes, with resultant fibrosis producing infertility

Question 38

Anaerobic niches include __________.

Answer 38

the colon, mouth, skin ("down in the pores"), and female genital tract

Question 39

Anaerobic bacteria usually cause ______ infections.

Answer 39

mixed (with aerotolerant bacteria)

Question 40

__________ is rather aerotolerant anaerobe that is found in many abscesses below the diaphragm.

Answer 40

Bacteroides fragilis

Question 41

Chlamydia trachomatis is an ____________.

Answer 41

obligate intracellular bacteria; it causes trachoma (a chronic infection of the conjunctivae that leads to scarring), sexually transmitted urethritis, neonatal conjunctivitis, and neonatal pneumonia

Question 42

Mycoplasmic bacteria lack __________.

Answer 42

cell walls, thus they are resistant to drugs that attack bacterial cell walls

Question 43

Mycoplasma pneumoniae causes __________.

Answer 43

community-acquired pneumonia ("walking pneumonia," that is, a milder pneumonia); it adheres to respiratory epithelia and destroys host cells by producing hydrogen peroxide and superoxide

Question 44

Walking pneumonias do not have _________.

Answer 44

product/phlegm