Copyright © 2006, M. S. Kuhlenschmidt 2... · Corynebacterium = "club bacterium". Club shape forms...


TaxonomyTaxonomy

Related to Related to MycobacteriumMycobacterium and and NocardiaNocardia duedueto similar cell wall antigens and chemicalto similar cell wall antigens and chemicalcomposition; described as the "CMN Group".composition; described as the "CMN Group".

One unifying feature is the presence ofOne unifying feature is the presence ofmycolicmycolic acids.acids.

Genus is diverse; some of the species are pathogenic.Genus is diverse; some of the species are pathogenic.

The Genus The Genus CorynebacteriumCorynebacterium


Morphology is based on Morphology is based on C. C. diphtheriaediphtheriae,,a human pathogen. Cells called a human pathogen. Cells called diphtheroiddiphtheroid..

Other organism having cells of a Other organism having cells of a diphtheroiddiphtheroid shapeshape((ActinomycesActinomyces bovisbovis, , ActinomycesActinomyces viscosusviscosus).).

Relatively recent molecular taxonomy effortsRelatively recent molecular taxonomy effortsled to reorganization of genus. This is driven,led to reorganization of genus. This is driven,in part, because in part, because corynebacteriacorynebacteria are pathogensare pathogensthat affect that affect immunocompromisedimmunocompromised humans.humans.

Several organisms have been renamed recently.Several organisms have been renamed recently.


Cellular and Cultural Characteristics

Corynebacterium = "club bacterium".

Club shape forms because of weakenedcell wall in some regions; results in swelling.

Cell morphology described as "palisades”(picket fence) or Chinese letters. V, L, and Y shapes are common - resembling filamentous

Cell size is 2 to 6 µm long and0.5 to 1 µm in diameter.


Cellular morphology of the CorynebacteriaSightly cruved, club-shaped, Gram + rods often

resembling Chinese Letters


NonNon--motile.motile.

Not acid fast, despite the presence ofNot acid fast, despite the presence ofmycolicmycolic acids.acids.

Do not form spores.Do not form spores.


DiseaseDisease--Causing SpeciesCausing Species

Because Because CorynebacteriumCorynebacterium species are species are commensalscommensalsof the skin and mucous membranes, isolatingof the skin and mucous membranes, isolatingone from a clinical sample does not mean it isone from a clinical sample does not mean it isthe cause of disease.the cause of disease.

We will discuss the more common pathogensWe will discuss the more common pathogensof animals.of animals.

BUT FIRSTBUT FIRST----a few words about the mosta few words about the mostcommonly known commonly known CorynebacteriumCorynebacterium species,species,which only infects humans...which only infects humans...


Best known species in genus; reason for Best known species in genus; reason for calling cells "calling cells "diphtheroiddiphtheroid".".

Causes diphtheria, a disease known at leastCauses diphtheria, a disease known at leastsince the days of Hippocrates.since the days of Hippocrates.

Lesions of tonsils and throat; formation ofLesions of tonsils and throat; formation ofa false membrane.a false membrane.

Symptoms are toxinSymptoms are toxin--mediated; mechanismsmediated; mechanismswellwell--described.described.

CorynebacteriumCorynebacterium diphtheriaediphtheriae


Organisms colonize mucus membranes of the respiratory tract and produce neuraminidase: yields pyruvate from degradation of N-Acetylneuraminic acid (Sialic Acid) acts as a growth stimulant.

C. diphtheriae also produces diphthin, which is a protease that inactivates IgA.

Toxigenic strains carry the gene tox, which resides on certain bacteriophages; lysogenization leads to toxigenicity.


The toxin is a single polypeptide of 62,000 daltons

Contains a single disulfide cross-link.

Digestion with trypsin gives 2 fragments, A and B.

The B (binding) fragment attaches to cell surfaces then proteases release the A (active) fragment to enter the cell.

Toxin acts as an ADP-ribosyltransferase, inactivating translation factor EF2.


Diptheria Toxin Action


Cellular and Cultural CharacteristicsCellular and Cultural Characteristics

Small Small pleomorphicpleomorphic rod that can berod that can bemistaken for a mistaken for a coccuscoccus..

Slow growth Slow growth in vitroin vitro..

High lipid content in cell wall; colonies seemHigh lipid content in cell wall; colonies seemlike flakes of wax (like flakes of wax (mycolicmycolic acids acids -- waxes).waxes).

Slightly hemolytic.Slightly hemolytic.

CorynebacteriumCorynebacterium pseudotuberculosispseudotuberculosis


Highly variable biochemical reactions.Highly variable biochemical reactions.

Differentiating species of Differentiating species of CorynebacteriumCorynebacteriumcan be difficult.can be difficult.

API (RAPID) API (RAPID) CoryneCoryne Strip also available.Strip also available.


Caseous Lymphadenitis

Caused by Caused by C. C. pseudotuberculosispseudotuberculosis..

Mostly in sheep and goats, but also affectsMostly in sheep and goats, but also affectsother animals; e.g., ulcerative other animals; e.g., ulcerative lymphangitislymphangitis horseshorses

Suppuration and necrosis of the lymph nodes.Suppuration and necrosis of the lymph nodes.

Disease can be accompanied by chronic pneumoniaDisease can be accompanied by chronic pneumoniaor pleurisy.or pleurisy.


QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.


Corynebacterium pseudotuberculosis - Caseous Lymphadenitis


Hepatic Abscess - Corynebacterium pseudotuberculosis


Local inflammation at site of entry; organismLocal inflammation at site of entry; organismtravels to regional lymph node causing enlargementtravels to regional lymph node causing enlargementand suppuration.and suppuration.

Easy to isolate organisms from superficial locations.Easy to isolate organisms from superficial locations.

Draining material can spread organism toDraining material can spread organism toother animals; this is exacerbated since organismother animals; this is exacerbated since organismis somewhat environmentally stable.is somewhat environmentally stable.

Disease can be spread mechanically as inDisease can be spread mechanically as inshearing sheep; usually superficial location.shearing sheep; usually superficial location.


Pulmonary form of disease also documented.Pulmonary form of disease also documented.

Disease also believed to be spread by ingestionDisease also believed to be spread by ingestion

Pigeon Fever in horses Pigeon Fever in horses -- intramuscular abscessesintramuscular abscessesusually restricted to arid climates usually restricted to arid climates -- western US western US BrazilBrazil-- usually in fall or early winterusually in fall or early winter

enters via penetrating wounds, injection sitesenters via penetrating wounds, injection sites

affected muscles are swollen and edematousaffected muscles are swollen and edematous


Facultative intracellular pathogen with someFacultative intracellular pathogen with somesuspected virulence factors:suspected virulence factors:

PhospholipasePhospholipase D/D/sphingomyelinasesphingomyelinase D;D;degrades mammalian cell membranes;degrades mammalian cell membranes;antibodies against this are protective.antibodies against this are protective.

Study of wildStudy of wild--type and type and phospholipasephospholipase DDmutant strainsmutant strains

WildWild--type strain causes type strain causes abscessationabscessation atatsite of infection and spreads to regionalsite of infection and spreads to regionallymph node.lymph node.

Mutant strain has reduced ability toMutant strain has reduced ability toestablish infection and cannot spread.establish infection and cannot spread.


HeatHeat--stable stable pyogenicpyogenic factor;factor;old report with little mentioned recently.old report with little mentioned recently.

Large amounts of surface lipid;Large amounts of surface lipid;promotes survival in phagocyte and promotes survival in phagocyte and pyogranulomapyogranulomaformationformation

similar to case for similar to case for MycobacteriumMycobacterium and and RhodococcusRhodococcus..

Virulence Factors with a Weaker ConnectionVirulence Factors with a Weaker Connection


Immunity and TreatmentImmunity and Treatment

Antibodies produced in response to infection;Antibodies produced in response to infection;attempts to stimulate immunity by vaccinationattempts to stimulate immunity by vaccinationare not totally successful, but reduce size andare not totally successful, but reduce size andnumber of abscesses.number of abscesses.

Susceptible to many antibiotics, but pus andSusceptible to many antibiotics, but pus anddebris in lesions protect the organism.debris in lesions protect the organism.


DiphtheroidDiphtheroid bacillus.bacillus.

Short, stumpy rods that can beShort, stumpy rods that can bea little thicker at one end.a little thicker at one end.

Found in clumps in cultures and clinical specimens.Found in clumps in cultures and clinical specimens.

NonNon--motile, nonmotile, non--sporeformingsporeforming, non, non--encapsulated.encapsulated.

C. C. renalerenale Group: Group: renalerenale, , pilosoumpilosoum, , cystitidiscystitidis


Strongly GramStrongly Gram--positive.positive.

Have Have pilipili for adhesion.for adhesion.

Likes serum and blood in growth medium.Likes serum and blood in growth medium.

Produces Produces ureaseurease; could be considered; could be considereda virulence factor?a virulence factor?


C. C. renalerenale causes causes pizzlepizzle rot! Also infectious rot! Also infectious pyelonephritispyelonephritis..

C. C. renalerenale also causes also causes pyelonephritispyelonephritis, , urethritisurethritis andandcystitis in cattle, sheep and horses.cystitis in cattle, sheep and horses.

Highly adapted to urinary tract and diesHighly adapted to urinary tract and diesquickly in the environment.quickly in the environment.

Tends to affect female animals with pregnancyTends to affect female animals with pregnancyand parturition as susceptibility factors.and parturition as susceptibility factors.

Transmitted by splashing urine on another Transmitted by splashing urine on another animal.animal.

Diseases


UreaseUrease is part of adaptation to urinary tract;is part of adaptation to urinary tract;splits urea to ammonia and COsplits urea to ammonia and CO22. Alkaline urine. Alkaline urineaids organism's ability to penetrate theaids organism's ability to penetrate therenal epithelium.renal epithelium.

Ammonia causes prepuce irritation and ulceration Ammonia causes prepuce irritation and ulceration -- provides the opportunity for C. provides the opportunity for C. renalerenale colonizationcolonizationin the case of in the case of PizzlePizzle RotRot

Clinical signs are often seen late in the disease;Clinical signs are often seen late in the disease;loss of condition, painful urination, blood in urine.loss of condition, painful urination, blood in urine.


Urine examined to aid diagnosis; can GramUrine examined to aid diagnosis; can Gramstain directly or centrifuge to Gram stain sediment.stain directly or centrifuge to Gram stain sediment.

C. C. renalerenale can be isolated from healthy animals.can be isolated from healthy animals.


Immunity and TreatmentImmunity and Treatment

Treatment often unsuccessful in advanced cases.Treatment often unsuccessful in advanced cases.

Treatment monitored by culture of urine.Treatment monitored by culture of urine.

Acquired immunity seen in some cases.Acquired immunity seen in some cases.

No vaccines.No vaccines.


C. C. ulceransulcerans

Bovine mastitis.Bovine mastitis.

C. C. bovisbovis

CommensalCommensal?? May cause mastitis.?? May cause mastitis.

May aid protection against moreMay aid protection against morevirulent pathogens.virulent pathogens.

Other Other CorynebacteriumCorynebacterium SpeciesSpecies


ArcanobacteriumArcanobacterium pyogenespyogenes•• Formerly Formerly CorynebacteriumCorynebacterium pyogenespyogenes, , ActinomycesActinomyces

pyogenespyogenes

•• Slender G+ rods, slightly curvedSlender G+ rods, slightly curved and often clubbed at and often clubbed at one end (reason classified as one end (reason classified as CorynebacteriumCorynebacterium))

•• Normal flora on mucus membranes of healthy animalsNormal flora on mucus membranes of healthy animals

•• Requires wound or primary viral insultRequires wound or primary viral insult--opportunisticopportunistic

•• A major pusA major pus--former (abscesses) in former (abscesses) in herbivorsherbivors (mastitis)(mastitis)

•• Produces a single hemolytic Produces a single hemolytic exotoxinexotoxin -- pyolysinpyolysin (PLO) (PLO)

•• Antibodies to PLO are passively protectiveAntibodies to PLO are passively protective


An Arcanobacterium (Actinomyces )pyogenesMutant Deficient in Production of the Pore-Forming Cytolysin Pyolysin Has Reduced

Virulence

B. H. Jost, J. G. Songer, and S. J. Billington Department of Veterinary Science and Microbiology, The University of Arizona,

Tucson, Arizona 85721

Infection and Immunity, April 1999, p. 1723-1728, Vol. 67, No. 4


Pyolysin (PLO)Thiol-activated cytolysin family (TACY)

cholesterol-binding, pore forming exotoxins

hemolytic activityhemolytic activity

Considering all aspects of microbial-host cell inter-actions that occur during an infectious disease, which host cells are likely the most important targets, (from the microbe’s point of view) of hemolysins?

Copyright © 2006, M. S. Kuhlenschmidt 2... · Corynebacterium = "club bacterium". Club shape forms...

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