Common Bacterial Pathogens 2 Flashcards Preview

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Flashcards in Common Bacterial Pathogens 2 Deck (44):
1

Streptococci are _________.

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

2

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

staphylococcus; streptococcus

3

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

aureus; SSNA

4

Group A streptococci are ______.

streptococcus pyogenes

5

Group A typically cause __________.

throat infections, wound infections, and post-strep sequlae

6

What factors allow streptococcus pyogenes to cause pharyngitis?

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)

7

People recover from strep by ________.

developing antibodies against M proteins

8

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

damaging the heart valves and exposing sequestered antigens

9

The three most common causes of bacterial endocarditis are _________.

staphylococcus aureus, streptococcus viridans, and coagulase negative staphylococci

10

Gamma hemolysis is __________.

actually non-hemolytic

11

Beta-hemolysis is ____________.

complete clearance of RBCs

12

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

meningitis and septicemia; pneumonia, sinusitis, and bronchitis

13

Streptococcus pneumoniae can become pathogenic by __________.

developing anti-phagocytic capsules

14

In pneumococcal pneumonia, the alveolae will have _________.

exudates due to the inflammatory response

15

Predisposing factors to pneumococcal pneumonia include ___________.

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

16

Enterococcus faecium and faecalis are _____________.

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

17

Nosocomial infections are _____________.

infections acquired in hospitals

18

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

clostridium

19

Clostridia are _________.

strict anaerobes that form endospores

20

The genus clostridium includes _________.

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

21

Clostridium difficile causes ___________.

nosocomial diarrhea and (more rarely) pseudomembranous colitis

22

Suspect C. difficile when patients develop diarrhea _________.

after being admitted to the hospital and receiving antibiotics

23

Clostridium tetani often infect sites of local infection because _________.

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

24

C. tetani toxin blocks __________.

inhibitory neurons of the central nervous system

25

Clostridium botulinum is a __________.

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

26

The cause of gas gangrene is ____________.

clostridium perfringens

27

C. perfringens kills cells by __________.

secreting alpha toxin, which cleaves phospholipases that then induces apoptosis

28

Enterotoxins are not __________.

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

29

_________ and _________ are Gram-negative rods.

Eschericia coli; pseudomonas aeruginosa

30

ETECs are ____________.

enterotoxogenic bacteria

31

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

disrupt the electrolyte balance of the gut

32

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

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

33

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

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

34

Neisseria are _________.

Gram-negative diplococci

35

Neisseria gonorrhoeae can fight leukocytes by ________.

using their pili to interfere with neutrophil killing

36

Because neisseria gonorrhoeae infect mucosal surfaces, they __________.

induce an inflammatory response that creates exudate

37

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

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

38

Anaerobic niches include __________.

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

39

Anaerobic bacteria usually cause ______ infections.

mixed (with aerotolerant bacteria)

40

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

Bacteroides fragilis

41

Chlamydia trachomatis is an ____________.

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

42

Mycoplasmic bacteria lack __________.

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

43

Mycoplasma pneumoniae causes __________.

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

44

Walking pneumonias do not have _________.

product/phlegm

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