Flashcards in Pasturellaceae Deck (36)
General characteristics of Pasturellaceae
gram negative, non-motile, pleomorphic coccobacilli
oxidase and catalase positive
many species have requirement for heamin, B vitamins or particular AAs
Many species contain extracellular toxins that are members of the repeat in structural toxin (RTX) family
Cell wall of Pasturellaceae
LPS: major feature of gram negatives; antigenic and highly potent toxin
Outer membrane: structural, porins, reducible, scavenge nutrients
PG layer: hard skeleton- lends structure to bacilli/cocci
Inner membrane: lots of basic functions of cell--> classical 2 membrane structure.
Hemophilus: general characteristics
Small to medium size gram negative, coccobacilli
capable of fermenting sugar
will not grow on some lab media, CO2 is sometimes required
Require factor X (hemin) or V factor (nicotinamide adenine dinucleotide) or both.
Found on mucosal surfaces of animals and humans and are extremely host specific.
IRON is NECESSARY
Species of hemophilus
H. paragallinarum- infectious coryza in fowl
H. parasuis- glasser's disease/polyserositis in pigs
H. agni- septicemia in lambs
H. felis- vaginitis and pleurisy in cats
H. somni- thromboembolic meningoencephalitis (TEME), pneumonia, vaginitis in cows
H. somni- mastitis, epididymitis/orchitis, metritis, septicemia, meningoencephalitis, pneumonia and polyarthritis in sheep.
Virulence factors of hemophilus
Capusle: H. parasuis and H. paragallinarium produce well-defined capsular polysacchardies- form protective coat around the bacteria and allows it to evade host defenses. tend to be sero-type specific antigen. H parasuis has 15 serotypes and H paragallinarium has 6.
H. paragallinarum infection
fowl coryza: chickens affected most; turkeys and pigeons resistant.
Clinical signs: inflammation of the turbinates and sinus epithelium, disruption of the turbinates, acute air sacculitis
Infection usually more severe following viral or mycoplasma infection
H. parasuis infection
carried in pig nasopharynx, may cause respiratory disease, most often manifests as a fibrinous, lobar pneumonia.
Glasser's disease: fibrinous inflammation of the serous surfaces or joints; may affect pericardium, pleura, peritoneum, joints and in sever cases the meninges.
Signs: swollen joints and lameness, fever, pleuritis and possibly meningitis
spectrum of cattle diseases;
Thromboembolic meningoencephalitis (TEME): clinical signs include weakness, fever, staggering ,somnolence, dyspnea, paralysis and death
Repro failure may be a result of endometriosis, metritis or late abortion. mastitis and vaginitis may also occur.
H. somni lesions
fibrinous meningitis with thrombosis and necrosis; pneumonia with pleuritis and arthritis
Hemophilus virulence factors
LPS and lipooligosaccharides
LPS endotoxins of hemphilus differ from enterobacteriaceae in that they don't have side chains
Endotoxin major role is to cause inflammation
CHO moiety predominant antigenic component of LPS or LOS
Exotoxins: H. somni produces a weak hemolysin
Proteases: destory mucosal IgA
Outer membrane proteins that bind to the Fc receptor of normal IgG block binding of specific IgG
Binding nucleotides on cell surface enhance survival in or killing of phagocytic cells.
Host specificity of hemophilus
due to the abilit of a species to obtain iron from a single host.
under iron-limiting conditions, the bacteria that produce outer-membrane proteins are able to obtain iron from host transferrin; iron regulated outer membrane proteins (IROMPS)
Diagnosis of hemophilus
isolation of bacteria from normally sterile sites or in pure culture to confirm isolate is pathogen and not part of normal flora.
Most isolates from animals require only NAD and will grow on commercial chocolate agar or on blood agar with streak of staph to provide NAD.
Actinobacilli: General characteristics
Closely related to hemophilus
gram negative coccobacilli, pleomorphic, small, but long filaments may occur
fermentative without gas production
Some species will grown on Mac, but don't require X or V factors
Colonies of most species will be sticky and difficult to remove from agar
Many species carry genes for the RTX hemolysis toxins (like hemophilus)
Normal habitat of actinobacilli
respiratory, alimentary and urogenital tract
may occur as commensals or pathogens
Actinobacilli oxygen requirements
Actinobacilli species- important
A. lignieresii- wooden tongue in cattle, skin abscess in sheep
Pigs (horses): A suis- neonatal septicemia, pneumonia, endocarditis
Pigs: A. pleuropneumoniae- pleuropneumonia
Horses: A. equuli- neonatal septicemia (sleepy foal disease)
Sheep: A. semini- epididymitis
Virulence factors of actinobacilli
Capsules produced by A. pleuropneumoniae and A. capsulatus
All species contain LPS (endotoxin) with O side chains. Only LPS of A. pleuropneumoniae has been documented to contribute to lesions
Exotoxins: extracellular RTX toxins identified in A. pleuropneumonia, A. lignieresii, A. equuli, and A. suis.
A. lignieresii- cultural characteristics
Slightly sticky, non-hemolytic colonies formed on blood agar
Pink colonies on MacConkey agar (ferment lactose)
In smears of pus or granules, clumps of organisms and club shaped bodies may be seen.
A. lignieresii diseases
wooden tongue (hard abscesses in soft tissue) and rumenitis in cattle
Skin abscesses in sheep
Abscesses contain bacteria, sulphur granules.
A. pleuropneumoniae- clinical signs and lesion presentation
cause of contagious pleuropneumonia of swine (absolutely specific). Lesions can be consolidated and congested, or hemorrhagic with necrosis.
Trembling, anorexia, dyspnea, fever and hemorrhage from nose and mouth
Animals may die with 24 hours
Diagnosis of A. pleuropneumoniae
12 serotypes described based on capsular antigens but different serotypes predominate in different countries.
Colonies tend to be sticky and difficult to remove from plate
Some isolates may be smooth.
Requires V factor
Pasturella- general characteristics
gram negative, short to medium sized coccobacilli
normal commensals of mucosal membranes of respiratory tract of mammals
Pasturella-general O2 reqs.
most strains facultatively anaerobic
Pasturella- do they ferment?
ferement glucose, gas isn't produced
mucoid colonies on culture, coccobacilli with capsules
Four main capsule types A, B, D and E
Type D produces dermonecrotoxin
Capsular serogroup A and somatic serotypes 1,3 and 4 predominant in fowl cholera
P. multocida diseases
septicemia, penumonia and rhinitis
13 serotypes recognized based on capsular antigens
Disease results usually following stress (transport, bad weather, castration or other predisposing factors)
Cattle: Type A1 causes shipping fever
Sheep: pneumona- caused by All serotypes
M. hemolytica- toxin
produces a leukotoxin related to the RTX hemolysin of E. coli and exotoxins of A. pleuropneumoniae