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Veterinary Bacteriology & Mycology > Streptococcus > Flashcards

Streptococcus Flashcards

1
Q

What are 6 major characteristics of Streptococcus?

A
  1. Gram-positive cocci arranged in chains
  2. facultative anaerobe
  3. non-motile and non-spore forming
  4. fastidious growth requirement (unlike Staph)
  5. cannot grow in high salt media (unlike Staph)
  6. catalase negative (unlike Staph)
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2
Q

What does it mean that Streptococcus has a fastidious growth requirement? How can this affect isolation?

A

requires a nutritionally rich media for growth

cannot survive for long away from animal host without proper media

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3
Q

What are the 2 major medias used for culturing Streptococcus?

A
  1. Edward media for selective isolation and identification (esculin hydrolysis)
  2. Blood agar for the determination of hemolysin toxin produced by isolates
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4
Q

In what 3 groups do blood agar plates separate Streptococcus?

A
  1. β-hemolytic: most pathogenic
  2. α-hemolytic: most commensal Streptococci in the upper respiratory system
  3. γ-hemolytic: most fecal Streptococci
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5
Q

What proteins and carbohydrate polymers serve for protection and serotyping Streptococcus?

A
  1. hyaluronic acid - makes up mucoid and useful in serotyping
  2. Lancefield carbohydrate - useful in Lancefield serotyping multiple species into a cluster/set
  3. protein G
  4. protein M - useful for serotyping within a species by ELISA and vaccine production
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6
Q

What are the 7 steps of Streptococcus spp. serotyping using the common cell wall carbohydrate, Lancefield carbohydrate?

A
  1. add extraction reagent 1 into test tube
  2. add one bacterial colony and mix
  3. add extraction reagent 2 and mix
  4. add reagent 3 and mix
    5 now the cell wall carbohydrate is extracted and ready to mix with antibody
  5. mix bacterial extract with one drop of the antibody kit in the relevant circle on the card
  6. correct combination of antibody and antigen (carbohydrate) causes agglutination
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7
Q

Out of the serogroups that the Streptococcus spp. are grouped into using Lancefield serogrouping, which ones are clinically important?

A

serogroups A, B, C, D, E, and G

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8
Q

What 2 tests are used to tell if an isolated bacteria is Streptococcus? What 2 tests differentiate between Steptococcus spp.?

A
  1. Gram-stain: should be G+ and look like a chain of cocci
  2. catalase test: should test negative
  3. blood agar
  4. Lancefield serotyping
    - both differentiate between spp. and pathogenicity
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9
Q

How do most equine and canine isolates of Steptococcus spp. identify on the blood agar test?

A

most are β-hemolytic

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10
Q

What is the most challenging aspect of Streptococcus in respect to vaccine development?

A

diverse serotypes within each species

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11
Q

What habitat on the host is Streptococcus found on?

A

commensal organisms in the skin, upper respiratory system, tonsil, GI tract, lower urogenital tract, udder/teat duct (milk/dairy products)

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12
Q

Since Streptococcus is commensal in the normal flora, how does it cause infection? In what 4 ways can it spread between animals?

A

it’s an opportunistic organism, so disease will occur when the bacteria enter cuts, abrasions, wounds; when the immune system is weakened; or as a result of other primary diseases

  1. direct contact
  2. aerosol
  3. fomites
  4. ingestion
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13
Q

What are the 3 broad classes of virulent factors of Streptococcus?

A
  1. structural compounds
  2. enzymes
  3. toxins
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14
Q

What are the 4 main surface structures that contribute to the virulence of Streptococcus? What do each do?

A
  1. LIPOTEICHOIC ACID: adhesion, cytotoxic for most host cells
  2. CAPSULE (slime layer): adhesion, hide the surface of the bacterial cell by depositing host sialic acid residues on their surface - helps avoid recognition of phagocytes and prevents complement-assisted opsonization
  3. M PROTEIN: adhesion, inhibition of phagocytic ingestion, binds Fc region of IgG to prevent opsonization
  4. PROTEIN G: competes with complement to bind with Fc region of IgG, binds and accumulated IgG on bacterial surface through non-immune binding to prevent opsonization
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15
Q

What 4 enzymes contribute to the virulence of Streptococcus? What do these enzymes do?

A
  1. NUCLEASE: facilitated the liquefaction of pus into resources/substrates for growth, DNAse (A, C) or RNAse (B, D) to destroy host cells and defense
  2. STREPTOKINASE: catalyze conversion of plasminogen to plasmin, leading to digestion of fibrin, which allows for the lyse of blood clots
  3. HYALURONIDASE: hydrolyzes hyaluronic acid to reach between host cells as a defense mechanism
  4. C5a PEPTIDASE: destroy chemotactic signals from C5a to keep host defense cell recruitment to a minimum
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16
Q

What 3 toxins contribute to the virulence of Streptococcus? What do these toxins do?

A
  1. HEMOLYSIN: destroys RBCs, neutrophils, macrophages, and platelets
  2. EXOTOXINS (Streptolysin): hemolytic on blood sugar, kills cells including phagocytes, inhibits phagocyte attraction (chemotaxis)
  3. PYROGENIC EXOTOXINS: fever, rash resembling strawberrys, cardiac and liver necrosis, T cell division, release cytokines - superantigen shock, increase endothelium and BBB permeabillity (shock)
17
Q

Where does Streptococcus infection begin? What does it become?

A

throat, eye, ear, skin, urogenital infections

pneumonia, endocarditis, meningitis, shock

18
Q

Streptococcus spp. advance from what 4 directions?

A

skin, throat, mammary glands, urogenital system
- then becomes systemic

19
Q

What are the 4 groups of Streptococcus based on clinical significance?

A
  1. throat and dermatological infection: S. pyogenes
  2. aggressive/virulent infections of upper respiratory tract and systemic infections: S. pneumoniae
  3. reproductive tract of women: S. agalctiae
  4. emerging zoonotic diseases of humans that migrate from animals - S. suis, S. gallolytics
20
Q

What zoonotic disease do S. sius and S. gallolytics cause in humans?

A

S. suis from pigs —> meningitis, septic shock, arthritis, subcutaneous hemorrhage, pneumonia, permanent hearing loss, death

S. gallolytics from chicken —> human colorectal cancer, osteomyelitis

21
Q

What 3 conditions does S. pyogenes cause in humans

A
  1. scarlet fever = pharyngitis: strep throat, painful swallowing, lymph node and tonsil infection, fever
  2. rash: pathognomonic strawberry rash that resembles sandpaper texture and goosebumps
  3. cutaneous lesions: necrotizing skin fasciitis, leading to “flesh-eating” by its pyrogenic exotoxins
22
Q

What 2 diseases are caused by Streptococcus in horses? What species causes them?

A
  1. Strangles - throat infection equivalent to scarlet fever, where pus accumulates in the throat regions, suppurative conditions in the genital region, and mastitis, purpura hemorrhagica
    - S. equi subsp. Equi
  2. generalized infection and reproductive tract infection - vaginitis, abortion, postpartum endometritis, septicemia, pneumonia
    - S. dysgalatiae subsp. Equismilis
    - S. equi subsp. Zooepidemicus
23
Q

What are the 8 major signs of Strangles from Streptococcus infection?

A
  1. abscesses in the lymph nodes of the head and neck
  2. coughing
  3. difficulty swallowing
  4. fever up to 106 degrees F
  5. yellow-colored nasal discharge from nose and eyes
  6. thick pus filling the guttural pouch
  7. large and swollen head
  8. purpura hemorrhagica
24
Q

What 2 diseases are caused by Streptococcus infection in pigs? What species causes each?

A
  1. throat infection (porcine strangles) - pus accumulation in throat region, feeder boils, contagious cervical lymphadenitis, purpura hemorrhagica
    - S. porcinus (rare)
  2. generalized infection - aggressively affects ear, eyes, lung, brain, and joints/bones; deafness, blindness, septicemia, meningitis, polyarthritis
    - S. suis (most common problem in pig industry)
    - S. equi subsp. Zooepidemicus (occasionally)
25
Q

What are the 8 major findings in S. suis infection? How can this affect humans?

A
  1. pneumonia
  2. septicemia
  3. meningitis/ataxia/loss of balance/shaking
  4. polyarthritis/lameness
  5. abortion
  6. metritis
  7. blindness
    8 deafness

streptococcal toxic shock - purpura hemorhagica on the leg and gangrene extending to the foot

26
Q

What are the 4 most common conditions associated with Streptococcus infection in pets? Which species causes them?

A
  1. throat infection (pet strangles) - S. canis
  2. generalized infection - aggressive systemic form causing septicemia, pneumonia, and meningitis - S. canis
  3. eye/ear infection - S. canis
  4. reproductive infection - vaginitis abortion, endometritis, mastitis, prostatitis - mostly S. agalactiae, but can be S. canis
27
Q

What species of Streptococcus causes the most aggressive infections in pets? What species is considered an emerging problem?

A

S. canis

S. equi subsp. Zooepidemicus

(S. agalactiae, S. pneumoniae, S. suis, S. pyogenes = occasional problem)

28
Q

What are 7 effects of S. canis infection in pets?

A
  1. blindness (conjunctivitis)
  2. deafness (otitis)
  3. septicemia
  4. contagious lymphadenitis (like scarlet fever)
  5. pneumonia and fibrinous pleurisy
  6. vaginitis, abortion, metritis - also S. agalactiae
  7. urinary tract infection (cystitis) - also S. agalactiae
29
Q

What are the 4 species of Streptococcus causing disease in ruminants?

A
  1. S. uberis: mastitis
  2. S. dysgalatiae: acute contagious/environmental mastitis, polyarthritis
  3. S. agalatiae: chronic contagious mastitis
  4. S. equi subsp. Zooepidemicus: metritis, abortion, mastitis
30
Q

The α-hemolytic (viridians) Streptococci also tend to be dangerous, especially in humans. Where are they usually found? What do they cause? Give some examples.

A

normal flora of the oral cavity, intestine, and urethra

endogenous infection: dental caries, endocarditis, mixed infection within oral cavity (abscesses)

S. miti, S. mutans, S. salivarius, S. sanguis, S. miller

31
Q

What part of the Streptococcal cell is used for ELISA serology testing?

A

protein M

32
Q

What are 5 practices that can help prevent and control Streptococcus infection?

A
  1. reducing stress caused by overcrowding, poor ventilation, and high humidity
  2. practice good hygiene, strict sanitation of facilities and instruments
  3. cleaning wounds
  4. segregation of infected animals and early treatment
  5. control of primary diseases that interact with Streptococcus

Veterinary Bacteriology & Mycology (47 decks)

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