Lesson 5

Question 1

Large, Gram-positive rods (but few nonpathogenic species are Gram-negative)
 Endospores produced
 Aerobes or facultative anaerobes
 Growth on non-enriched media
 Most species motile, catalase-positive and
oxidase-negative
 Majority are non-pathogenic environmental
organisms
 Bacillus anthracis (non-motile) causes anthrax
 Bacillus licheniformis is implicated in sporadic abortions in cattle and sheep
 Usual habitat: environment
 Colonial characteristics:

Answer 1

Bacillus species

Question 2

5 mm diameter, flat, dry, greyish
and with a ‘ground glass’ appearance after
incubation for 48 hours, curled outgrowths
from the edge of the colony impart a
characteristic, ‘medusa head’ appearance

Answer 2

B. anthracis

Question 3

same with B. anthracis but are larger
and with greenish tinge. Majority of strains
produce wide zone of complete haemolysis
around the colonies.

Answer 3

B. cereus

Question 4

colonies are dull, rough, wrinkled
and strongly adherent to the agar that becomes
brown with age. Characteristic
hair-like
outgrowths are produced from streaks of the
organisms on agar media.

Answer 4

B. licheniformis

Question 5

Fatal peracute or acute septicaemic
anthrax

Answer 5

B. anthracis
Cattle, sheep

Question 6

Subacute anthrax with oedematous
swelling in pharyngeal region; an intestinal
form with higher mortality is less common

Answer 6

B. anthracis
Pigs

Question 7

Subacute anthrax with localized oedema;
septicaemia with colic and enteritis
sometimes occurs

Answer 7

B. anthracis
Horses

Question 8

Mastitis (rare)

Answer 8

B. cereus
Cattle

Question 9

Sporadic abortion

Answer 9

C. licheniformis
Cattle, sheep

Question 10

cause of abortion in cattle and sheep
associated with the feeding of contaminated silage or mouldy hay and diagnosed
by isolation in heavy, pure culture from foetal abomasal contents.

Answer 10

Infections with B. licheniformis

Question 11

Ruminants are highly susceptible, pigs and horses are moderately
susceptible to infection, while carnivores are comparatively resistant. Birds are
almost totally resistant to infection, due to their relatively high body temperatures

Answer 11

Anthrax

Question 12

encodes for exotoxin (protective antigen, oedema factor and lethal
factor)

Answer 12

Plasmid
PXO1

Question 13

encodes for capsule (inhibits phagocytosis)

Answer 13

Plasmid PXO2

Question 14

Bacillus species
Diagnosis:

Answer 14

(1) Carcasses of animals that have died from anthrax are
bloated, putrefy rapidly and do not exhibit rigor mortis. Dark, unclotted
blood may issue from the mouth, nostrils and anus. The carcasses of
such animals should not be opened because this will facilitate
sporulation, with the risk of long-term environmental contamination. (2)
Direct blood smears using blood specimen from tail vein of ruminant or
peritoneal fluid of pigs. (3) Bacterial culture using Blood Agar or
MacConkey Agar (4) Molecular detection thru PCR and (5) Ascoli test.

Question 15

Treatment and control: PenG or oxytet

Answer 15

Bacillus species

Question 16

Large, Gram-positive rods
 Endospores produced Anaerobic,
 catalase-negative and oxidasenegative
 Motile (except C. perfringens)
 Enriched media required for growth
 Colonies of C. perfringens
surrounded by zones of double
haemolysis

Answer 16

Clostridium species

Question 17

Detection and differentiation: Bacterial culture (but colonial morphology is
limited value), biochemical tests (commercial kits), PCR techniques, toxin
neutralization/ or protection tests, immunoassay methods

Answer 17

Clostridium species

Question 18

Large wide rods which rarely form endospores in vitro

Answer 18

C. perfringens

Question 19

thin rods which characteristically produce terminal endospore ( drumstick appearance)

Answer 19

C. Tetani

Question 20

Medium-sized rods which produce lemon- shaped endospores

Answer 20

C. chauvoei

Question 21

Pathogenic Clostridium species

Answer 21

*Neurotoxic clostridia
*Histotoxic clostridia
*Enteropathogenic and enterotoxaemia- producing clostridia
*Atypical clostridial organism

Question 22

a neurotoxin type of clostridial infection which affects many species
including humans.

Answer 22

Tetanus

Question 23

___________________ are highly susceptible,
____________________ moderately so and _____ are
comparatively resistant to Tetanus

Answer 23

Horses and humans
ruminants and pigs
carnivores

Question 24

are not susceptible to tetanus

Answer 24

Poultry

Question 25

The aetiological agent is _____________, a straight, slender, anaerobic,
Gram-positive rod with spherical endospores at the terminal part of the
cells which imparts a characteristic ‘drumstick’ appearance to sporulated
organisms

Answer 25

Clostridium tetani

Question 26

is haemolytic on blood agar (in vitro) due to the
production of tetanolysin, which also hasten the the replication of the
clostridial organisms in the tissues (in vivo).

Answer 26

Clostridium tetani

Question 27

, which is responsible for the clinical signs
of tetanus, is antigenically uniform and can be neutralized by antibodies
produced by the neurotoxin irrespective of serotype.

Answer 27

tetanospasmin

Question 28

Clostridium tetani is haemolytic on blood agar (in vitro) due to the
production of _________, which also hasten the the replication of the
clostridial organisms in the tissues (in vivo).

Answer 28

tetanolysin

Question 29

Necrotic tissue, foreign bodies and contaminating
facultative anaerobes in wounds may create the anaerobic conditions in
which _______ spores can germinate.

Answer 29

C. tetani

Question 30

include stiffness, localized spasms, altered heart and
respiratory rates, dysphagia and altered facial expression.

Answer 30

Clostridium tetani

Question 31

Spasm of masticatory muscles may lead to

Answer 31

Lockjaw

Question 32

Generalized muscle stiffness can result in a ________ stance
especially in horses.

Answer 32

‘saw-horse’

Question 33

incubation period of tetanus is usually between

Answer 33

5 and 10 days

Question 34

are usually associated with a shorter
incubation period and an increased tendency to generalized tetanus.

Answer 34

Wounds on or near the head

Question 35

________________ is may be due to use of
contaminated needles which inadvertently introduce
spores of C. botulinum during subcutaneous injection of
drugs, germinate and produce toxin.

Answer 35

Toxico-infectious botulism

Question 36

is effective in neutralizing unbound toxin
early in the course of disease; tetraethylamide and guanidine
hydrochloride (enhance transmitter release at neuromuscular junctions);
good nursing.

Answer 36

polyvalent antiserum

Question 37

an acute disease of cattle ( 3 months to 2 years old, and produce
endogenous infection) and sheep (any age, and produce exogenous infection)
caused by C. chauvoei, occurs worldwide. Cause of death is gangrenous
cellulitis and myositis caused by exotoxins produced by the replicating organisms,
or myocardial and diaphragmatic lesions if no premonitory lesions. Confirmatory
methods include fluorescent antibody techniques or PCR techniques applied to
specimens from lesions.

Answer 37

Blackleg

Question 38

clostridial infection of head
wounds caused by fighting is termed ______ manifested by oedematous
swelling of subcutaneous tissues of the head, neck and cranial thorax.

Answer 38

‘big head’

Question 39

: an abomasitis of sheep, is caused by the exotoxins of C. septicum which
occurs in winter during periods of heavy frost or snow.

Answer 39

Braxy

Question 40

which relates to the dark
discoloration of the skin observed at post-mortem examination) is an acute
disease that affects sheep and occasionally cattle

Answer 40

black disease

Question 41

, a major clinical feature of the
disease, is a consequence of extensive red cell destruction.

Answer 41

Haemoglobinuria