Chap 16: Aerobic gram-pos bacilli

Question 1

positive aerobic bacilli spore-forming genus

Answer 1

bacillus

Question 2

non-spore-forming bacteria include genera

Answer 2

corynebacterium, arcanobacterium, rhodococcus, listeria, erysipelothrix, gardnerella

Question 3

branching, non-spore-forming aerobic actinomycetes

Answer 3

nocardia

Question 4

non-spore-forming, nonbranching catalase-pos bacilli

Answer 4

corynebacterium

Question 5

based on 16S rRNA, corynebacteria are closely related to

Answer 5

mycobacteria and nocardiae

Question 6

corynebacteria can be divided into

Answer 6

nonlipophilic and lipophilic

Question 7

type of corynebacteria that are often considered fastidious and grow slowly on standard culture media; culture must be incubated at least 48 hrs before growth is detected

Answer 7

lipophilic corynebacteria

Question 8

on gram stain, corynebacteria are

Answer 8

slightly curved, gram-pos rods with unparallel sides and sligtly wider ends, producing the described “club-shaped”

Question 9

most significant pathogen of the group

Answer 9

C. diphtheriae; which causes diphtheria

Question 10

nondiphtheria corynebacterium spp. that produce disease in humans include, but are not limited to

Answer 10

corynebacterium amycolatum, corynebacterium pseudodiphtheriticum, corynebacterium pseudotuberculosis, corynebacterium jeikeium, corynebacterium striatum, corynebacterium ulcerans, corynebacterium urealyticum

Question 11

major virulence factor of C. diphtheriae

Answer 11

diphtheria toxin

Question 12

this toxin is produced by strains of C.diphtheriae infected with

Answer 12

lysogenic B-phage, which carries the tox gene for diphtheria toxin

Question 13

diphtheria toxin is exceedingly potent and is lethal for humans in amounts of

Answer 13

130 ng/kg of body weight

Question 14

toxicity is due to the

Answer 14

ability of diphtheria toxin to block protein synthesis in eukaryotic cells

Question 15

toxin is secreted by the bacterial cell and nontoxic until

Answer 15

exposed to trypsin

Question 16

trypsinization cleaves the toxin into

Answer 16

two fragments

Question 17

this fragment is responsible for the cytotoxicity

Answer 17

fragment A

Question 18

fragment that binds to receptors on the eukaryotic cells and mediates the entry of fragment A into the cytoplasm

Answer 18

fragment B

Question 19

enzyme required for elongation of polypeptide chains on ribosomes

Answer 19

adenosine diphosphoribose (ADPR)

Question 20

production of the toxin in vitro depends on environmental conditions

Answer 20

alkaline pH (7.8 tp 8.0), oxygen, iron concentration

Question 21

C. diphtheriae causes two diff. forms of disease in humans

Answer 21

respiratory and cutaneous diphtheria

Question 22

humans are the only natural hosts for c. diphtheriae

Answer 22

individuals vaccinated as children who have not revaccinated as adults are susceptible to infection

Question 23

c.diphtheriae is carried in the upper respiratory tract and spread by droplet infection or hand-to-mouth contact

Answer 23

incubation period averages 2 to 5 days

Question 24

illness begins gradually and characterized by

Answer 24

low-grade fever, malaise, and mild sore throat

Question 25

most common site of infection

Answer 25

tonsils or pharynx

Question 26

combination of cell necrosis and exudate forms a

Answer 26

tough gray-to-white pseudomembrane, which attaches to the tissues

Question 27

there's a potential for suffocation

Answer 27

if the membrane blocks the air passage or if it is dislodged, perhaps as the result of sampling for a throat culture

Question 28

toxin is also absorbed and can produce various systemic effects involving the

Answer 28

kidneys, heart, and nervous system, altho all tissues possess the receptor for the toxin and may be affected

Question 29

another effect of the toxin is

Answer 29

demyelinating peripheral neuritis, which can result in paralysis following the acute illness

Question 30

cutaneous diphtheria consists of

Answer 30

nonhealing ulcers with a dirty gray membrane

Question 31

commercial diphtheria antitoxin is producedin

Answer 31

horses

Question 32

drug of choice is

Answer 32

penicillin; erythromycin is used for penicillin-sensitive individuals

Question 33

c. diphtheriae is highly pleomorphic (many shapes) gram-pos bacillus that appears in palisades (cells lie in paraller rows) or as individual cells lying at sharp angles to another "V" and "L" formations

Answer 33

microscopy

Question 34

organisms often stain irregularly, especially when stained with methylene blue,

Answer 34

giving them a beaded appearance

Question 35

the metachromatic areas of the cell, which stain more intensely that other parts, are called

Answer 35

Babes-Ernst granules

Question 36

c.diphtheriae is a facultative anaerobe

Answer 36

grows best under aerobic conditions and has an optimal growth temp of 37 degrees, altho multiplication occurs within the range of 15 to 40 degrees C

Question 37

c. diphtheriae grows on nutrient agar, better growth is usually obtained on medium containing blood or serum, such as

Answer 37

loeffler serum or pai agars

Question 38

the organism can have a very small zone of B-hemolysis in this media

Answer 38

SBA

Question 39

a modification of Tinsdale medium, contains sheep blood rbs, bovine serum, cystine, and potassium tellurite

Answer 39

cystine-tellurite blood agar

Question 40

cbta is both

Answer 40

selective and differential medium

Question 41

when grown on cbta, corynebacteria form

Answer 41

black or brownish colonies from the reduction of tellurite

Question 42

useful in differentiating feature of C.diphtheriae, c.ulcerans, c.pseudotuberculosis

Answer 42

brown halo surrounding the colony on CBTA, owing to cystinase activity

Question 43

all medically important corynebacteria are

Answer 43

catalase-positive and nonmotile

Question 44

the addition of iron too iron-starved cultures

Answer 44

inhibits production very quickly

Question 45

in vivo toxin testing is rarely done because the in vitro methods are

Answer 45

reliable, less expensive, and free from animal use

Question 46

the in vitro diphtheria toxin detection procedure is an immunodiffusion test first described by

Answer 46

elek

Question 47

elek test requires that reagents and antisera be carefully

Answer 47

controlled and titrated

Question 48

also available for detecting of the diphtheria toxin

Answer 48

rapid enzyme-linked immunosorbent assays and immunochromatographic strip assays

Question 49

is the most frequently recovered corynebacterium species from human clinical material

Answer 49

c.amycolatum

Question 50

part if the normal skin microbiota and has previously been misidentifies by clinical lab as

Answer 50

c.striatum, c.xerosis, c.minutissimum

Question 51

often associated with prosthetic joint infection and has been reported to cause blood-stream infection and endocarditis

Answer 51

c.amycolatum

Question 52

colonies of c.amycolatum are

Answer 52

flat, dry, have a matte or waxy appearance, and are nonlipophilic

Question 53

most strains have been reported to be resistant to wide range of antimicrobials, including

Answer 53

B-lactams, fluoroquinolines, macrolides, clindamycin, aminoglycosides

Question 54

named after johnson and kaye, who first linked this organism with human infections, appear to be part of the normal skin microbiota

Answer 54

c.jeikeium

Question 55

also the most common cause of corynebacterium-associated prosthetic valve endocarditis in adults; causes septicemia, meningitis, prosthetic joint infections, skin complications such as rash and subcutaneous nodules

Answer 55

c.jeikeium

Question 56

jeikeium resistant to wide range of antimicrobials, including

Answer 56

penicillins, cephalosporins, macrolides, aminoglycosides

Question 57

drug of choice for jeikeium is

Answer 57

vancomycin

Question 58

part of normal microbiota of human nasopharynx; an infrequent cause of infection

Answer 58

c. pseudodiphtheriticum

Question 59

c.pseudodiphtheriticum has been reported to cause

Answer 59

endocarditis uti cutaneous wound infections

Question 60

primarily a veterinary pathogen; infections are associated with contact with sheep and are rare

Answer 60

c. pseudotuberculosis

Question 61

often considered a commensal or skin contaminant

Answer 61

c.striatum

Question 62

most commonly associated with device-related infection; reported incases of endocarditis, septic arthritis, meningitis, pneumonia

Answer 62

c. striatum

Question 63

also a veterinary pathogen, causing mastitis in cattle and other domestic and wild animals

Answer 63

c. ulcerans

Question 64

most commonly associated with UTIs

Answer 64

c. urealyticum

Question 65

are actually gram-pos cocci that can appear rod-like that belong to the family of micrococcaceae

Answer 65

rothia spp.

Question 66

has been linked to bacteremia, endocarditis, pneumonia, other infections

Answer 66

rothia mucilaginosa

Question 67

member of normal human oropharyngeal microbiota and may be found in saliva and supragingival plaque

Answer 67

rothia dentocariosa