Gram Positive Bacilli Flashcards
(67 cards)
1
Q
General Characteristics of Corynebacterium
A
- free living saprophytes (water, soil, air), usual flora of animals and humans
- diphtheriae is the most significant pathogen, others typically only in ICPs
- falcultative, gram-positive, non spore-forming rods, have Babe-Ernst granules
2
Q
C. diphtheriae Virulence factors
A
- exotoxin - diphtheria toxin (only produced by some strains), inversely proportional to available iron
- can use IgG to block toxin
3
Q
Fragments of Corynebacterium diphtheriae
A
- A: active fragment is cytotoxic, inhibits protein synthesis
- B: binds to specific cell membrane receptors, mediates entry of fragment A
4
Q
Infections of Corynebacterium diphtheriae
A
- Respiratory infection, droplets spray, aerosol, or hand-to-mouth contact, unimmunized people are susceptible
- incubation 2-5 days, fever, malaise, sore throat, inflammatory response and tissue necrosis, tough gray-white pseudomembrane
- systemic infection when toxin is absorbed in bloodstream, affects kidneys, heart and nervous system
5
Q
Treatment of diphtheria
A
- administer antitoxin, produced in horses
- antiboitics to clear infection, penicillin or erythromycin
- vaccine available
6
Q
Cutaneous diphtheria
A
- prevalent in the tropics
- infection occurs at site of abrasion
7
Q
Culturing diphtheria
A
- Loeffler’s serum agar: demonstrates pleomorphism and metachromatic granules (Babe-Ernst)
- Cysteine-tellurite blood agar (CTBA): modified Tinsdale media, selective and differential, brown or grayish to black around colonies
8
Q
Identification of Corynebacterium diphtheriae
A
- identification by fermentation reactions, urease
- toxigenicity testing: must have toxin, Elek test, PCR
9
Q
C. amycolatum
A
most frequently recovered, common on skin, opportunistic, joint infections, endocarditis, sepsis (ICPs)
10
Q
C. jeikeium
A
infection from catheters or prosthetic vavles, endocarditis
11
Q
C. psuedodiphtheriticum
A
opportunistic, usually endocarditis
12
Q
C. psuedotuberculosis
A
contact with sheep, dermonecrotic toxin
13
Q
C. striatum
A
rare infections, normal flora
14
Q
C. ulcerans
A
mastitis in cattle, contact with animals or unpasteurized milk
15
Q
C. urealyticum
A
urinary pathogen, highly urease positive
16
Q
Characteristics of Coryneform
A
- speciated if found in normally sterile site, or if it’s the prominent organism of a specimen
- may require urine samples if predominant
17
Q
Most significant pathogen of Corynebacterium group
A
C. diphtheriae
18
Q
Major virulence factor of C. diphtheriae
A
exotoxin
19
Q
toxigenic fragments
A
- A: active fragment, cytotoxic, inhibits protein synthesis
- B: binds to specific cell membrane receptors, mediates the entry of fragment A
20
Q
C. diphtheriae on Loeffler’s serum agar
A
metachromatic granules (Babes-Ernst granules)
21
Q
C. diphtheriae on CTBA
A
brown to grayish black around colonies
22
Q
confirm identification of C. diphtheriae
A
urease from fermentation reactions
23
Q
toxigenicity testing of C. diphtheriae
A
Elek test
24
Q
Major virulence factors of Listeria monocytogenes
A
- the hemolysin Listeriolysin O (hemolytic and cytotoxic)
- p60 surface protein (induces phagocytosis b/c of increased adhesion to mamalian cells)
25
Major identifiers of Listeria
- grows at 4C, catalase positive
| - umbrella motility at 25C, tumbling motility
26
transmission of E. rhusiopathiae
occupational exposure (animals like sheep)
27
identification of E. rhusiopathiae
catalase negative and TSI positive (H2S production)
28
identification of Arcanobacterium
catalase negative, narrow zone of beta hemolysis, produces black dot under colonies
29
Nocardia
aerobic, weakly acid-fast, gram-variable, morphologically resemble fungi
30
N. cyriaciageorgica and N. farcinica
cause confluent bronchopneumonia, no sulfur granules
31
N. braziliensis
causes actinomycotic mycetomas (cutaneous infection), sulfur granules present
32
Actinomadura
colonies can be red, resemble Nocardia but non-acid-fast
| have a molar tooth appearance after 2 week incubation
33
Rhodococcus
salmon-pink colonies, zig-zag growth
34
Streptomyces
smell woodsy w/ waxy, heaped colonies
35
Bacillus anthracis
- agent of anthrax, nonhemolytic on SBA
- identification: nonhemolytic on SBA, medusa head or egg whites, non-motile, produces lecithinase, string of pearls morphology
36
Virulence factors of Bacillus anthracis
protein exotoxin (EF, LF and PA)
37
Infections cause by Bacillus anthracis
most are cutaneous, pulmonary infection (“woolsorter’s disease”), GI anthrax, Injectional anthrax
38
Bacillus cereus
motile (flagella), hemolysin positive
39
Rothia dentocariosa
- normal oral flora
| - bacteremia, endocarditis, wound infection, eye infection
40
- gram-positive, non spore forming rods
| - found in nature, can be in produce, dairy, processed meat
characteristics of Listeria monocytogenes
41
Listeriolysin O (hemolytic and cytotoxic), phospholipase C, catalase, superoxide dismutase, surface protein p60
virulence factors of Listeria monocytogenes
42
- adults: penetration of the intestine
- ICP/elderly: septicemia, meningitis, endocarditis
- Pregnant women: premature labor, spontaneous abortion
- newborn: meningitis
infections of L. monocytogenes
43
- grow at cold temperature, catalase positive
- hippurate hydrolysis negative
- umbrella motility at 25C, tumbling motility
- CAMP test block
identification of L. monocytogenes
44
- ampicillin or penicillin G
| - TMP-SMZ (sulfa drugs) if penicillin allergy
treatment of L. monocytogenes
45
- gram-positive, non spore forming
- in nature worldwide, found in animals
- infection through occupational exposure (hands/fingers, self-limiting)
E. rhusiopathiae characteristics
46
- cell surface antigens, endothelial cell adherence
| - enzymes
E. rhusiopathiae virulence factors
47
- catalase negative, TSI positive (H2S)
| - requires CO2, SBA or CA, alpha hemolysis
E. rhusiopathiae identification
48
pharyngitis, cellulitis
Infections of arcanobacterium
49
- low virulence
- catalase negative, narrow beta hemolysis
- black dot under colony
- treat with erythromycin
arcanobacterium
50
- stains gram-variable
- causes bacterial vaginosis, observe clue cells, treat with clindamycin
- use human blood bilayer tween agar
Gardnerella vaginalis
51
- aerobic, weakly acid-fast, gram-variable
- morphologically resemble fungi
- found in the environment, affect ICPs
Nocardia
52
- bronchopneumonia, no sulfur granules
| - high mortality rate
N. cyriaciageorgica and N. farcinica
53
- cutaneous infection
| - sulfur granules
N. braziliensis
54
- wet mounts, branching filaments
- parafin bait test, substrate hydrolysis/utilization
- antimicrobial susceptibility
identification of Nocardia
55
treatment of Nocardia
resistant to penicillin, susceptible to sulfnoamides
56
red colony, molar tooth appearance, non acid-fast
actinomadura
57
zig-zag growth, salmon-pink colony
Rhodococcus
58
- waxy, heaped colonies
| - smell woodsy, branching with chains and spores
Streptomyces
59
- found in livestock, acquired by contamination of food or a wound
- large spore-forming bacilli, nonhemolytic
Bacillus anthracis
60
- polypeptide capsule
| - potent exotoxin (edema factor, lethal factor, protective antigen)
virulence factors of B. anthracis
61
- cutaneous (black eschar)
- respiratory (woolsorter's disease)
- GI infection
- injectable infection
infections of B. anthracis
62
nonhemolytic, medusa head or beaten eggwhites, nonmotile, produces lecithinase, string of pearls when exposed to penicillin
identification of B. anthracis
63
treatment of B. anthracis
most susceptible to penicillin
64
Food poisoning (diarrheal syndrome, emetic form), infections of the eye, septicemia, meningitis, etc.
infections of B. cereus
65
- exotoxin (enterotoxin), pyogenic toxin
| - spores, enzymes, beta-lactamase
virulence factors of B. cereus
66
aerobic, beta hemolytic, motile, spores, hemolysin positive
identification of B. cereus
67
treatment for B. cereus
vancomycin (eye infection), clindamycin and gentamycin combo
