Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
Family: Fusobacteriaceae
Genus: Fusobacterium necrophorum
Gram-negative, non-spore-forming anaerobe, fusiform or pointed rod bacteria. its normal
inhabitant is the alimentary tract of animals and humans the source of infection is always
endogenous. Virulent spp. Include Fusobacterium necrophorum(spp. Necrophorum and spp.
fundiliforme ) Fusobacterium equinum, and Fusobacterium nucleatum and others. They
differ morphologically, biochemically, and biologically. The organism is an opportunistic
pathogen that causes numerous necrotic conditions called (necrobacillosis) such as bovine
hepatic abscesses, ruminant foot abscesses and human oral infections. The pathogenic
mechanism of necrophorum is complex and not well defined. Several toxins, such as
leukotoxin, endotoxin, haemolysin, haemagglutinin and adhesin, have been implicated as
virulence factors. Among these, leukotoxin and endotoxin are believed to be more important
than other toxins in overcoming the host’s defence mechanisms to establish the infection.
Diseases:
Foot abscesses in Cattle and Sheep: infection of the interdigital and coronary skin and
adjacent soft tissues and is the major cause of lameness in beef and dairy cattle. Foot rot in
sheep is a mixed bacterial infection of the interdigital skin. Thrush (hoof infection)
horses caused by F. necrophorum.
Calf diphtheria (necrotic laryngitis) is another disease associated with F necrophorum. It is
characterized by necrotic lesions in the larynx, oral cavity or pharynx and usually occurs in
calves up to 2 years of age. In severe cases the calf dies from subsequent aspiration
pneumonia.
Bovine mastitis (summer mastitis) caused by F necrophorum alone has been reported
F. necrophorum is the primary aetiological agent of bovine hepatic abscesses, from which it
is frequently isolated in pure culture
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
Diagnosis :
1- Gram stain reveals long gram –ve fusiform rods with characteristic beading.
2- Colonies are small, smooth, yellowish white, and may be α or β hemolytic.
3- To differentiate Fusobacterium from other anaerobic bacteria some tests should
be included:
Test
Result
Vankomycin
Resistant
Kanamycin
Susceptible
Colistin
Susceptible
4- To differentiate subspecies the following tests should be performed:
Fusobacterium
spp.
Indole
production
Bile
solubility
Esculin
hydrolysis
Lipase
production
Glucose
fermentation
F. necrophorum
+
+
_
+
_
F.nucleatum
+
+
_
_
_
F.equinum
+
_
_
+
_
F.russii
_
+
_
_
_
F.varium
+
_
_
_
+
Treatment :
Erythromycin , Tetracycline and penicillin
For prevention of bovine footrot bacterin-toxoid is used
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
Genus Bordetella
Bordetella is a genus of small (0.2 - 0.7 µm), Gram-negative coccobacilli of the phylum
proteobacteria. Bordetella species, with the exception of B. petrii, are obligate aerobes as
well as highly fastidious, or difficult to culture. Three species are human pathogens (B.
pertussis, B. parapertussis, B. bronchiseptica); one of these (B. bronchiseptica) is also
motile.
Disease
B. pertussis and occasionally B. parapertussis cause pertussis or whooping cough in humans.
B. parapertussis strains can colonise sheep.
B. bronchiseptica causes several diseases in mammals, including kennel cough and atrophic
rhinitis in dogs and pigs, respectively. 'Kennel Cough' is upper respiratory tract infection in
dogs (canine infectious tracheobronchitis or Bordetellosis) It is highly contagious in dogs.
The disease is found worldwide and infect a very high percentage of dogs in their lifetime.
Clinical signs (dry hacking cough followed by retching)occur three to four days after
exposure and, if uncomplicated with other agents, will last around 10 days. However after
the infection has been resolved, the affected animal will continue to shed the bacteria for 6 to
14 weeks and can spread the disease to other susceptible animals during that time.
B. avium responsible for contagious upper respiratory tract infection called turkey coryza
B. hinzii the genus found primerly as a commensal of poultry respiratory tract cause similar
diseases in birds.
Pathogenesis
B. bronchiseptica, B. pertussis and B. parapertussis causes respiratory disease Transmission
occurs by direct contact, or via respiratory aerosol droplets, or fomites. Bacteria initially
adhere to ciliated epithelial cells in the nasopharynx and this interaction with epithelial cells
is mediated by a series of virulence factors including
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
1.
protein adhesions(include filamentous haemaglutinin, pertactin, fimbriae)
assisting in adherence to epithelial cells, some of these are also involved in
attachment to immune cells. and group of toxins including
2.
pertussis toxin (unique to B. pertussis) causes increase mucus secretion by
respiratory mucosa characteristic of paroxysmal stage of whooping cough.
3.
adenylate cyclase-hemolysin toxin, which aids in the evasion of innate
immunity. The toxin is delivered to phagocytic immune cells upon contact.
Immune cell functions are then inhibited in part by the resulting
accumulation of cyclic AMP.
4.
Dermonecrotic toxin responsible for pathogenicity in atrophic rhinitis
5.
Osteotoxin it is a novel cytotoxic protein of B. avium.
6.
Tracheal cytotoxin
7.
lipopolysaccharide
Diagnosis:
Diagnosis can be done through the following:
1- Diagnosis is usually based on the symptoms and a history of recent exposure as well
as postmortem observations.
2- Bacterial cultures: B. pertussis does not grow on common lab. media and it requires
supplementation with charcoal , starch and blood, Bordet Gengou agar is the medium
of choice for its isolation. Smith and Baskerville medium selective for B.
bronchiseptica . most strains of Bordetella grow on MacConkey agar giving small
bluish-gray colonies.
3- Gram stain: Bordetella cells are small gram negative rods to coccobacillary form
4- Antigenically can be diagnosed by slide agglutination test.
5- PCR.
Treatment
The most common are tetracycline or trimethoprim-sulfa, Bronchodilators and even aerosol
therapy can be used.
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
Vaccination and prevention.
More commonly, for best protection an intranasal vaccine containing both parainfluenza and
Bordetella is used. Intranasal vaccines create localized immunity that greatly reduces the
incidence of clinical signs and illness.
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
Family: Pasteurellaceae:Genus Haemophilus
Haemophilus spp. is a small, nonmotile Gram-negative bacterium in the family
Pasteurellaceae. The family also includes Pasteurella and Actinobacillus. it is a commensal
organism of the mucus membrane of animal and human.
Diseases :
There are many spp. Included in this genus the most important are:
Organism
Host
Disease
Haemophilus
influenza
Human
Bacteremia, meningitis
H.paragallinarium
Chicken
Infectious coryza
H.felis
Cat
Rhinitis, conjunctivitis
H.parasuis
Pigs
Glasser's dis., meningitis, pneumonia,
septicemia
Naturally-acquired disease caused by H. influenzae seems to occur in humans only. In
infants and young children (under 5 years of age), H. influenzae type b causes bacteremia
and acute bacterial meningitis. Occasionally, it causes epiglottitis (obstructive laryngitis),
cellulitis, osteomyelitis, and joint infections. Nontypable H. influenzae causes ear
infections (otitis media) and sinusitis in children, and is associated with respiratory tract
infections
(pneumonia)
in
infants,
children
and
adults.
Infectious coryza is an acute respiratory disease of chickens. The most common clinical
signs are nasal discharge, facial swelling, lacrimation, anorexia, and diarrhea. Decreased feed
and water consumption retards growth in young stock and reduces egg production in laying
flocks. infectious coryza is regarded as Haemophilus paragallinarum, an organism that can
be either V-factor dependent or independent. infectious coryza has been reported as the
second most important bacterial disease associated with mortality after salmonellosis.
Virulence factors:
1. H. influenzae does not produce any demonstrable exotoxins
2. Endotoxin bacterium's outer membrane lipooligosaccharide (LOS) is thought to play
a role in inflammation.
3. All virulent strains produce neuraminidase and an IgA protease.
4. Fimbriae increase the adherence of bacteria to mucosal cells in vitro, and they are
required for successful colonization of the nasopharynx.
5. capsule formation =The capsule material is antiphagocytic, and it is ineffective in
inducing the alternative complement pathway, so that the bacterium can invade the
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
blood or cerebrospinal fluid without attracting phagocytes or provoking an
inflammatory response and complement-mediated bacteriolysis. For this reason,
anticapsular antibody, which promotes both phagocytosis and lysis of bacteria, is the
main factor in immune defense against Haemophilus infections.
Diagnosis
Diagnosis can be done through:
 Gram stain: a small, non-motile Gram-negative
 Culture: Haemophilus "loves heme", more specifically it requires a precursor of heme
in order to grow. Nutritionally, Haemophilus prefers a complex medium and requires
preformed growth factors that are present in blood, specifically X factor (i.e., hemin)
and V factor (NAD or NADP). In the laboratory, it is usually grown on chocolate
blood agar. The heat releases X and V factors from the RBCs and turns the medium a
chocolate brown color. The bacterium grows best at 35-37oC and has an optimal pH
of 7.6. it is generally grown in the laboratory under aerobic conditions or under slight
CO2 tension (5% CO2), although it is capable of glycolytic growth and of respiratory
growth using nitrate as a final electron acceptor. the causative agent of infectious
coryza is regarded as Haemophilus paragallinarum, an organism that can be either Vfactor dependent or independent.
 On blood agar Haemophilus colonies cluster around staphylococcus streak line in a
phenomenon called satellitism.
 Serology: A range of tests have been described for the detection of antibodies to H.
paragallinarum in chickens e.g. enzyme-linked immunosorbent assay (ELISA)
 a new-generation diagnostic test based on the PCR technique.
Family: Pasteurellaceae:Genus Haemophilus
Haemophilus spp. is a small, nonmotile Gram-negative bacterium in the family
Pasteurellaceae. The family also includes Pasteurella and Actinobacillus. it is a commensal
organism of the mucus membrane of animal and human.
Diseases :
There are many spp. Included in this genus the most important are:
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
Organism
Host
Disease
Haemophilus
influenza
Human
Bacteremia, meningitis
H.paragallinarium
Chicken
Infectious coryza
H.felis
Cat
Rhinitis, conjunctivitis
H.parasuis
Pigs
Glasser's dis., meningitis, pneumonia,
septicemia
Naturally-acquired disease caused by H. influenzae seems to occur in humans only. In
infants and young children (under 5 years of age), H. influenzae type b causes bacteremia
and acute bacterial meningitis. Occasionally, it causes epiglottitis (obstructive laryngitis),
cellulitis, osteomyelitis, and joint infections. Nontypable H. influenzae causes ear
infections (otitis media) and sinusitis in children, and is associated with respiratory tract
infections
(pneumonia)
in
infants,
children
and
adults.
Infectious coryza is an acute respiratory disease of chickens. The most common clinical
signs are nasal discharge, facial swelling, lacrimation, anorexia, and diarrhea. Decreased feed
and water consumption retards growth in young stock and reduces egg production in laying
flocks. infectious coryza is regarded as Haemophilus paragallinarum, an organism that can
be either V-factor dependent or independent. infectious coryza has been reported as the
second most important bacterial disease associated with mortality after salmonellosis.
Virulence factors:
1. H. influenzae does not produce any demonstrable exotoxins
2. Endotoxin bacterium's outer membrane lipooligosaccharide (LOS) is thought to play
a role in inflammation.
3. All virulent strains produce neuraminidase and an IgA protease.
4. Fimbriae increase the adherence of bacteria to mucosal cells in vitro, and they are
required for successful colonization of the nasopharynx.
5. capsule formation =The capsule material is antiphagocytic, and it is ineffective in
inducing the alternative complement pathway, so that the bacterium can invade the
blood or cerebrospinal fluid without attracting phagocytes or provoking an
inflammatory response and complement-mediated bacteriolysis. For this reason,
anticapsular antibody, which promotes both phagocytosis and lysis of bacteria, is the
main factor in immune defense against Haemophilus infections.
Diagnosis
Diagnosis can be done through:
 Gram stain: a small, non-motile Gram-negative
Bacteriology lecture--------------------------------------------------------------------------------------------Dr. Zina AL-Shami
 Culture: Haemophilus "loves heme", more specifically it requires a precursor of heme
in order to grow. Nutritionally, Haemophilus prefers a complex medium and requires
preformed growth factors that are present in blood, specifically X factor (i.e., hemin)
and V factor (NAD or NADP). In the laboratory, it is usually grown on chocolate
blood agar. The heat releases X and V factors from the RBCs and turns the medium a
chocolate brown color. The bacterium grows best at 35-37oC and has an optimal pH
of 7.6. it is generally grown in the laboratory under aerobic conditions or under slight
CO2 tension (5% CO2), although it is capable of glycolytic growth and of respiratory
growth using nitrate as a final electron acceptor. the causative agent of infectious
coryza is regarded as Haemophilus paragallinarum, an organism that can be either Vfactor dependent or independent.
 On blood agar Haemophilus colonies cluster around staphylococcus streak line in a
phenomenon called satellitism.
 Serology: A range of tests have been described for the detection of antibodies to H.
paragallinarum in chickens e.g. enzyme-linked immunosorbent assay (ELISA)
 a new-generation diagnostic test based on the PCR technique.