Bacteriology pyogenic infections

Question 1

pyogenic

Answer 1

produce pus
acute inflammatory reaction
predominantly neutrophils
cause disease as extracellular bacteria

Question 2

pyogranulomatous inflammation

Answer 2

mixture of chronic and acute inflammation
mixture of macrophages, neutrophils, lymphocytes

Question 3

granulomatous inflammation

Answer 3

chronic inflammation
We will classically see central necrosis surrounded by giant epithelioid cells, macrophages, lymphocytes, some granulocytes, and surrounded by a thick fibrous capsule

Question 4

necrotizing inflammation

Answer 4

We will classically see just cellular debris, potentially a few toxic, inflammatory cells and the causative bacteria e.g., gram positive spore-forming rods

Question 5

staphylococcus type of bacteria

Answer 5

gr + cocci
form clusters in liquid media
facultative anaerobe
opportunistic

Question 6

Staphylococcus aureus

Answer 6

humans and other domestic species (incl. horses)
coagulase positive

Question 7

staphylococcus pseudointermedius

Answer 7

most common pathogen in dogs
coagulase positive

Question 8

coagulase test

Answer 8

differentiates between
weakly virulent and highly virulent staphylococci
positive are more highly virulent

Question 9

where are staphylococcus normally found?

Answer 9

normal flora of skin
* especially near mucocutaneous junctions
* Moist areas of the body
* Distal nasal passage, external nares, near rectum

May also be found in animal products and in the environment due to contamination
* Relatively LONG LIVED in the environment (problem for control)

Question 10

How do staphylococci cause disease

Answer 10

Staphs are GOOD pathogens (need little compromise)
Virulence factors
* Capsule or pseudocapsule (anti-phagocytic properties)
* Exotoxins – leucotoxins/hemolysins
* Intracellular survival (chronic infections)
* Biofilm formation
* Others; urease, superantigens etc

Strain variation in virulence factors & all are not constitutively expressed

Question 11

capsule/pseudocapsules

Answer 11

• Anti-phagocytic properties
• important becuase major defence mechanism against Staphylococci is phagocytosis
• Non-pathogenic (coagulase- negative) Staphylococci are easily phagocytosed and therefore killed

Question 12

endotoxins

Answer 12

Wide range of different exotoxins
Hemolysins/Leukotoxins are important for virulence
Cytotoxic (damage cells) and lethal
Leucotoxins also kill phagocytes – therefore help evade immune system

Question 13

facultative intracellular bacteria

Answer 13

Allows S. aureus to (3 points):
* Evade killing by phagocytes
* Evade immune system (antibodies)
* Evade antibiotics which act extracellularly

Results in persistence of infection (chronicity) in SOME cases
not all Staphylococci have this ability (strain variation) nor can they do this all the time (genes not constitutively expressed)

Question 14

What diseases do staphylococci cause (general)?

Answer 14

pyogenic, may be chronic (intracellular)
Staphylococci cause a WIDE RANGE of DISEASES in domestic animals
Few are pathognomic for Staphs!
they are associated with pyogenic infections
they may be associated with chronic infection

Question 15

streptococci type of bacteria

Answer 15

Gram positive cocci that form chains
Facultatively anaerobic
pyogenic

Question 16

Where are streptococci normally living?

Answer 16

Widely distributed in nature
Pathogenic species are most commonly found on animals and humans:
* on the mucus membranes of upper respiratory tract, lower genitourinary tract and GIT
* also on skin

Some pathogenic species may live in the environment as saprophytes
can be normal flora

Question 17

streptcoccus zooepidemicus

Answer 17

major pathogen of horses
normal flora

Question 18

Streptococcus equi

Answer 18

only on carrier animals
causes disease in horses but less than S. zooepidemicus

Question 19

S. dysgalactiae and S. agalactiae

Answer 19

cause mastitis in cows
S. agalactiae in carrier animals
S. dysgalactiae in normal flora

Question 20

how do streptococci cause disease?

Answer 20

range of virulence factors that are thought to aid in the pathogenesis of disease
Primarily act by:
* Avoiding phagocytosis
* Killing phagocytes & causing inflammation
* BUT, species causing disease in animals do NOT have intracellular survival as a major host defence mechanism

Question 21

How do streptococci avoid phagocytosis

Answer 21

M Protein
* MAJOR virulence factor of Streptococci
* Anti-phagocytic properties – both PMNs & macrophages
* Induces antibody production which are protective!!!

Capsules
* Only present on some strains and species

Killing Phagocytes
* Wide range of different exotoxins
* Hemolysins are best described
* cytotoxic for RBC, WBC and platelets

Question 22

hemolytic patterns

Answer 22

beta-hemolytic streptococci cause most of the important diseases in animals including diseases in Horses, Cattle, Dogs
α-hemolytic are also important - especially in Cattle, humans, and becoming so in dogs
non-hemolytic Streptococi are usually non-pathogenic

Question 23

What kind of dz do streptococci cause?

Answer 23

acute, short duration
cleared with production of protective antibodies
NO intracellular survival
BUT type III sensitivity can cause chronic dz due to antibodies
strangles, mastitis, neonatal septicemia, pneumonia, endometritis, necrotising fasciitis

Question 24

strangles

Answer 24

Streptococcus equi equi (NOT normal flora)
Cervical lymphadenitis
Major contagious disease of horse worldwide (carrier state)

Question 25

mastitis

Answer 25

Streptococci are major cause of mastitis Three species of importance (S. agalactiae, S. dysgalactiae, S. uberis) S. agalactiae is contagious (carrier state)

Question 26

pneumonia

Answer 26

**streptococci zooepidemicus** (horses, dogs, pigs), **canis** (dogs and cats), equisimilis (pigs) lower respiratory tract infections in a variety of species

Question 27

neonatal septicemia

Answer 27

caused by streptococci Observed in a range of species including foals, piglets, puppies and kittens Localization in many other body sites can occur

Question 28

endometritis

Answer 28

Caused by Strep. equi ss **zooepidemicus** Most common cause of endometritis, which is a major disease in **brood mares**

Question 29

necrotising fasciitis

Answer 29

streptococci “Flesh Eating Bacteria!!!!” Grp G (S. canis) in dogs and cats or Grp A (S pyogenes) in humans

Question 30

how to treat streptococci

Answer 30

**Drainage** (if possible) is very important as thick walled abscesses involved Nursing care +/- others e.g. anti-inflammatory agents (NSAIDs) Antibiotics * **b-hemolytic streptococci are predictably sensitive to penicillin** * Streptococci are frequently **resistant to fluoroquinolones, aminoglycosides and tetracyclines** * **alpha hemolytic & enterococci** commonly have broader resistance to antibiotics including penicillin

Question 31

antibiotics for b-hemolytic streptococci

Answer 31

**b-hemolytic streptococci are predictably sensitive to penicillin**

Question 32

antibiotics for a-hemolytic streptococci

Answer 32

**alpha hemolytic & enterococci** commonly have broader **resistance to antibiotics including penicillin**

Question 33

Trueperella pyogenes and corynebacterium type of bacteria

Answer 33

gr + club shaped rods faculitative aerobic

Question 34

where does Trueperella pyogenes come from

Answer 34

Normal flora of the mucus membranes + skin of ruminants and pigs

Question 35

where does C. pseudotuberculosis come from?

Answer 35

Normal flora skin, mucous membranes & GIT Also found in the environment (survives up to 8 months) Found in lesions of infected animals which may act as primary reservoirs

Question 36

where does C. renale come from?

Answer 36

present in the genital tract of carrier cows and bulls

Question 37

Trueperella pyogenes and corynebacterium virulence factors

Answer 37

Exotoxins * Pyolysin & Phospholipase D * T. pyogenes, C. pseudotb Pili & urease production * C. renale & T. pyogenes (pili) Facultative intracellular bacteria * C. pseudotuberculosis

Question 38

What diseases does Trueperella pyogenes cause?

Answer 38

**The most common cause of pyogenic infections in cattle!!!** Other species may also be infected e.g. pigs, ruminants, dogs, humans Other species of bacteria may be present in lesions (mixed) Usually **initiated by trauma/viral infections** Lesions may be l**ocalised, regional or metastatic** **Many different organs** involved

Question 39

What diseases does Corynebacterium pseudotuberculosis cause?

Answer 39

**Caseous Lymphadentis (CLA) “Cheesy Gland”** * Major (economically important) disease of **sheep + goats** * Infection of **superficial lymph nodes** * Usually requires a break in skin e.g. shearing, castrating, * May disseminate (“thin ewe syndrome”) **Pigeon Breast/Pigeon Fever** * Diseases of **horses**, mostly in Western USA * Thick walled, external or (more rarely) internal **abscesses** (more severe dz), on breasts **Ulcerative lymphangitis** * Diseases of **horses** (and cattle) * Most commonly **hind limbs** * Spread via **lymphatics**, with **ulcerating lesions**

Question 40

C. renale causes what diseases?

Answer 40

**Infectious Pyelonephritis** * Disease in **cows** (not bulls; they are carriers), occasionally other species * Ascending infection * **Hemorrhagic cystitis, ureteritis, pyelonephritis** **“Pizzle Rot” (balanoposthitis)** * **Sheep** (and occasionally other species) – rams and whethers * increase protein in feed leads to **increased urea in urine** * C. renale produces urease which **breaks down urea to ammonia** which causes **irritation of skin of preputial opening** and which bacteria can invade