Gram Positive Rods Flashcards
1
Q
Bacillus
A
large gram-positive rapidly growing bacteria. Endospore-forming rods. Aerobic or facultative anaerobic. Ubiquitous in nature
2
Q
Bacillus anthracis
A
obligate mammalian pathogen that causes anthrax.
3
Q
What were Koch’s postulates based on?
A
anthrax bacilli
4
Q
B. anthracis virulence factors
A
- capsule
2. anthrax toxin
5
Q
B. anthracis Capsule
A
anti-phagocytic and made of polymers of G-glutamic acid. capsule is produced only in vivo
6
Q
Staining Pattern on Bacillus anthracis
A
capsule stain pink shadow with polychromatic methylene blue
7
Q
Anthrax Toxin
A
tripartite toxin consisting of edema factor, lethal factor, and protective antigen. Causes increased vascular permeability and cell necrosis
8
Q
Edema Factor
A
calmodulin-dependent adenylate cyclase. Inhibits neutrophil function
9
Q
Lethal Factor
A
zinc metalloprotease. Cell death, hypoxia-induced tissue injury/shock
10
Q
Protective Antigen
A
cell binding factor. Supports translocation into cell
11
Q
Anthrax Transmission
A
- dependent on susceptible animals for replication.
- Dependent on survival endospores in soil (exposure of carcass to oxygen increases sporulation).
- Ecological cycles of infection (sporulation and germination in the environment)
- Spores persist for decades in the ground
12
Q
Anthrax Pathogenesis
A
- ingestion of spores
- germination and spread locally and to local lymph node
- enters blood stream
- tripartite toxin severely impairs or kills neutrophils and macrophages
- bacteria multiplies in blood
- toxin causes release of inflammatory mediators from macrophages and fluid loss from cells.
- Death through septic shock
13
Q
Predisposing factors that increase exposure of animals to anthrax spores in soil
A
- history of previous anthrax deaths
- flooding: soil rearrangement brings endospores to surface, endospore concentration is increased in standing surface water as it recedes.
- soil conditions: alkaline, rich in calcium and nitrogen favors endospore survival
- warm temperature
- during drought conditions animals forage closer to the ground increasing chances of soil ingestion and mechanical injury to GI mucosa
14
Q
Common Forms of Anthrax in ruminants
A
- Peracute septicemia in ruminants
15
Q
Local Anthrax
A
occurs in less susceptible species. severe edema at site of entry
16
Q
Order of severity of anthrax
A
- cattle
- sheep
- horses
- goats
- dogs
- pigs
17
Q
Antemortem signs of peracute/acute septicemia
A
rapidly fatal disease, bleeding from orifices, shock, respiratory distress
18
Q
Postmortem signs of peracute/acute septicemia
A
dark, unclotted blood. Incomplete rigor mortis. Splenomegaly
19
Q
Anthrax diagnosis
A
differential diagnosis: blackleg, botulism, poisoning, snake bite, lightning strike, peracute babesiosis
20
Q
Anthrax Treatment
A
penicillin
21
Q
Anthrax Control
A
vaccinate healthy animals in endemic/high risk area. Proper carcass disposal in suspected cases. Prophylactic antimicrobial therapy in suspected exposure
22
Q
Listeria spp.
A
small, gram positive rods ubiquitous in the environment carried in a wide variety of animals as asymptomatic enteric carriers. capable of growing in a wide range of temperature, including in the refrigerator.
23
Q
Psychrophilic
A
can grow in the cold
24
Q
Listeria monoctyogenes
A
facultative intracellular bacteria
25
Listeria monocytogenes Pathogenesis
1. ingestion/inhalation/ entry via minute wounds in buccal mucosa
2. Intracellular growth leads to local cell death and focal micro abscess formation and/or generalized septicemia
26
Listeria Monocytogenes Virulence Factors
internalin, listeriolysin, act A
27
Internalin
adhesion, entry, phagocytosis
28
Listeriolysin O (Hemolysin)
required for intracellular replication
29
Act A
intercellular movement to adjacent cells through bacterially induced host actin polymerization
30
Listeria monocytogenes disease presentations
1. circling disease or silage disease of feedlot cattle or housed ruminants in winter/spring after feeding poor-quality silage.
2. Encephalitis: predominantly observed in ruminants. Bacteria invade through oral mucosa travel along trigeminal nerve and localize in brain
3. Septicemia: common in monogastric animals and newborn animals as a continuation of the fetal infection. Hemategenous spread through gravid uterus, and penetration of placenta cause abortion resulting in necrosis in spleen and liver
31
Listeria disease in ruminants
neurologic symptoms: Walking in circles. Unilateral trigeminal and facial nerve paralysis
32
Listeria monocytogenes diagnosis in cattle
antemortem: presumptive diagnosis from history and symptoms. In ruminants prominent post-mortem lesions microabscesses in brain tissue mostly in brain stem,
33
Listeria monocytogenes diagnosis in other animals
in monogastric animals and young ruminants: septicemic listeriosis occurs and the major lesions include focal hepatic necrosis, and hemorrhagic gastroenteritis
34
Erysipelothrix
small aerobic gram-positive rods. Widespread in tonsils and intestines of pigs, turkeys, sheep, cattle, marine mammals
35
Erysipelothrix Transmission
by ingestion
36
Erysipelothrix rhusiopathiae
most common in pigs and turkeys. Pigs are important reservoirs
37
Erysipelothrix rhusiopathiae
causes swine erysipelas (diamond skin disease). acute and sub-acute form- septicemia and skin lesions. Chronic form- endocarditis, polyarthritis and skin lesions
38
Erysipelothrix rhusiopathiae in turkey and other birds
Acute infection-septicemia
| Chronic Infection- endocarditis and arthritis
39
Erysipelothrix rhusiopathiae in Sheep
non-suppurative polyarthritis. Outbreaks of post dipping lameness
40
Non-suppurative polyarthritis
enter through the umbilicus or wounds and localize the joints
41
Erysipelothrix rhusiopathiae in Humans
localized cellulitis in fingers. Occupational hazard for veterinarians and people working in fish, poultry, and swine industry
42
Erysipelothrix rhusiopathiae Diagnosis
blood culture, PCR
43
Erysipelothrix rhusiopathiae Treatment
antimicrobial treatment for acute infections. Intrinsic resistance to vancomycin, aminoglycosides, sulphonamides reported
44
Erysipelothrix rhusiopathiae Control
1. treat and isolate infected animals.
2. Cull chronically affected animals.
3. Good hygeine practices
4. Vaccination in pigs and turkeys
45
Corynebacterium spp.
gram-positive, pleomorphic aerobic rods found in soil and other environmental surfaces. Contain unusual lipid-rich outer layer short chain mycolic acid in their cell wall. Survive in macrophages and cause chronic, granulomatous, infections. Many are commensals and opportunistic infections. Cause pyogenic/pyogranulomatous infections
46
Corynebacterium diphtheriae
Diphtheria toxin carried in bacteriophage kills healthy tissues in the respiratory system and the dead tissue forms a thick, gray coating in the throat or nose making it very hard to breath and swallow.
47
C. pseudotuberculosis
causes caseous lymphadenitis. Facultative intracellular pathogen, survive inside macrophages.
48
C. pseudotuberculosis Virulence Factor
Exotoxin phospholipase D. Enhances spread of bacteria by damaging endothelial cells and increasing vascular permeability and external lipid coat provides protection from hydrolytic enzymes in host phagocytes
49
C. pseudotuberculosis Pathogenesis
Bacterial replication in phagocytic cells, and inflammation leads to formation of abscesses. Abscess formation occurs in major peripheral lymph nodes
50
C. pseudotuberculosis
| Diagnosis
1. culture of purulent material from abscess
| 2. Serology using synergistic hemolysin inhibition test that detects antibodies to the phospholipase D endotoxin
51
What do positive titers for C. pseudotuberculosis indicate?
1. past resolved infections
2. recent exposure
3. recent vaccination
4. active lesions
52
C. pseudotuberculosis Treatment
not considered a curable disease. Animals of high value are treated by lancing and draining, surgical excision, systemic antibiotics, and intralesional antibiotics
53
C. pseudotuberculosis Control
biosecurity practices, culling of infected animals, hygiene and management practices. Vaccines available for sheep and goats. Proper hygienic shearing and purchase animals from negative herds.
54
C. pseudotuberculosis in horses
1. nitrate reducing biotype. Causes pigeon fever, mainly in California, Texas, and Midwest in summer and fall.
2. Bacteria causes ulcerative lymphangitis of lower extremities and abscesses in the pectoral region ventral abdomen
55
Corynebacterium renale group
a commensal of urogenital tract causes contagious bovine pyelonephritis in adult cows.
56
Rhodococcus equi
Gram-positive aerobic rods or coccobacilli. Facultative intracellular pathogen. One of the main causes of foal pneumonia
57
Rhodococcus equi Treatment
Standard empirical treatment is a combination of macrolide (erythromycin or clarithromycin) and rifampin
58
Rhodococcus equi Prevention
1. feed colostrum
2. hyperimmune plasma in high risk situations
3. dust control
4. remove manure from pasture
59
Nocardia Spp.
pleomorphic, gram-positive facultative intracellular bacteria ubiquitous in soil and water.
60
Sulphur Granules
present in the exudate of some Nocardia spp helpful in diagnosis of infection
61
Actinomyces bovis
causes pyogranulomatous osteomyelitis (lumpy jaw) of cattle
62
Lumpy Jaw
localized, chronic, progressive, granulomatous abscess involving mandible, the maxillae, or other bony tissues in the head. Caused by Actinomyces bovis
63
Actinomyces Diagnosis
Must request aerobic and anaerobic culture
64
Actinomyces Treatment
long term treatment with high dose despenicillin G, Iodides
| Surgical excision of foreign bodies/circumcised lesions
65
Actinomyces Control
minimize risk of mechanical injury, remove foreign bodies
66
Dermatophilus congolensis
aerobic, gram positive filamentous, branching bacteria inhabiting the skin of infected animals. Produce infectious motile zoospores. Divide in two planes giving tram-track appearance. Keratinolysis
67
What species produce infectious motile zoospores?
Dermatophilus congolensis
68
Motile Zoospores
chemotactic attracted to moist, damaged skin. Cause keratinolysis, which causes epidermal abscesses with hyperkeratosis
69
What species has tram-track appearance
Dermatophilus congolensis
70
Trueperella pyogenes
.An important opportunistic pathogen of cattle causing chronic purulent infections in ruminants and swine. Gram positive rod
71
Actinobaculum suis
anaerobic bacteria. Sexually transmitted. Causes porcine cystitis and pyelonephritis 2-4 weeks post-coitus. Death as a consequence of renal failure. Pathogenesis similar to bovine pyelonephritis.
72
What strains of B. anthracis are virulent?
those that are encapsulated and toxigenic
73
Listeria monocytogenes Treatment
treatment not attempted in CNS disease in ruminants
74
Caseous Lymphadenitis
chronic pyogranulomatous infection of lymph nodes in sheep and goats
75
Why is interpretation of C. pseudotuberculosis titers difficult in young animals?
because of the presence of maternal antibodies
76
Members of the Corynebacterium renale Group
C. renale, C. cystiditis, C. pilosum
77
What B. anthracis strains are virulent
those that are encapsulated and toxigenic
78
Bacillus anthracis transmission
dependent upon susceptible animals for replication and survival of endospores in soil
79
Predisposing factors that increase exposure of animals to anthrax spores in soil
1. history of previous anthrax deaths
2. flooding
3. soil conditions that favor endospore survival
4. drought animals forage closer to ground`
80
What form of anthrax infects cattle and sheep
per acute septicemia
81
Severity of Anthrax among species
1. cattle
2. sheep
3. horses
4. goats
5. dogs
6. pigs
82
Ante mortem signs of per acute septicemia
rapidly fatal disease, high fever, bleeding from orifices, shock, respiratory distress
83
Post mortem signs of per acute septicemia
dark unclotted blood, incomplete rigor mortis, splenomegaly
84
Listeria monocytogenes disease presentations
Encephalitis, septicemia
85
Listeria monocytogenes Encephalitis
predominantly observed in ruminants. Bacteria localize in brainstem
86
Listeria monocytogenes Septicemia
common in monogastric animals and newborn animals as a continuation of the fetal infection. Hematogenous spread to gravid uterus and penetration of placenta cause abortion resulting in necrosis in spleen and liver
87
Symptoms of Listeria monocytogenes in ruminants
dullness, turning or twisting head to one side, walking in circles. Unilateral trigeminal and facial nerve paralysis
88
For which bacteria does the vaccine have to strictly adhere to species label?
Corynebacterium pseudotuberculosis
