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Bacteriology/ Mycology > Staphylococcus > Flashcards

Staphylococcus Flashcards

1
Q

What kind of bacteria is seen in this image?

A

Staphylococcus

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2
Q

What are the 2 main culture media for growth of staphylococcus bacteria?

A

Mannitol salt agar containing high salt (NaCl) concentration (6.5–10%)
2. Blood agar β α γ

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3
Q

What kind of bacteria is staphylococcus? Is it catalase positive or negative? Is it motile? Does it form spores?

A

Gram positive cocci arranged in grape-like clusters • Facultative anaerobe • Non-motile (non-flagellated) • Non-spore forming • Catalase positive (detoxify H2O2) • Grow on media containing high salt (> 6.5-10%)
✓ E.g. Mannitol salt agar

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4
Q

What bacteria does manitol salt agar support the growth of? What bacteria does it inhibit growth of?

A

• It selectively supports growth of the following Gram-positive bacteria:
1. Staphylococcus

  1. Enterococcus
  2. Listeria
  3. Micrococcaceae

• However, it inhibits growth of most of:

  1. Gram-negative bacteria
  2. Streptococcus
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5
Q

In this image what kind of staphylococcus is seen?

A.) Alpha

B.) Beta

C.) Gamma

A

B.) Beta

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6
Q

In this image what kind of staphylococcus is seen?

A.) Alpha

B.) Beta

C.) Gamma

A

A.) Alpha

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7
Q

In this image what kind of staphylococcus is seen?

A.) Alpha

B.) Beta

C.) Gamma

A

c.) gamma

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8
Q

What staphylococcus bacteria causes this growth on a manitol salt agar plate? What cases the yellow coloring?

A

This is S aureus. It ferments manitol and changes the color of the agar from red to yellow.

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9
Q

What staphylococcus bacteria does not ferment manitol and uses this regular manitol salt agar media?

A

S. Epidermidis

S. epidermidis does not ferment manitol and no agar color change.

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10
Q

What Staphylococcus bacteria grows on this purple agar base which contains 1% maltose? What is causing the yellow colony? The white colony? The bottom colony?

A

Purple agar base containing 1% maltose:

✓ S. intermedius (left)

✓ S. aureus (right; yellow)

✓ S. hyicus (bottom)

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11
Q

What is the purpose of blood agar?

A

t allows determination of the type of hemolysin toxin produced by the isolates

  1. Beta….. Dangerous Staph. spp.
  2. alpha
  3. gamma
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12
Q

What does an alpha staphylococcus look like on an blood agar? What does it mean?

A

Alpha is an incomplete hemolysis. The color of these colonies are usually green.

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13
Q

What does an Beta staphylococcus look like on an blood agar? What does it mean?

A

The colonies would be clear and produce yellow haze around it. This is from complete hemolysis.

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14
Q

What does an Gamma staphylococcus look like on an blood agar? What does it mean?

A

Gamma - has no change in media, it shows no hemolyis

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15
Q

What color is S. Aureus on blood agar? What does it mean when they are yellow in color? Where does the yellow pigment come from?

A
  1. Hemolysis by Staph. aureus
  2. Yellow / golden colony due to a golden colored carotenoid pigment staphyloxanthin (it is antioxidant)
  3. Yellow colored Staph. aureus are more pathogenic.
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16
Q

What methods are available to diagnose staphylococcus isolates from suspected cases?

A
  1. Gram stain: shape/stain color
  2. Biochemical tests (biotyping) e.g. hemolysis, catalase, coagulase, and other typing methods
  3. Molecular biology e.g. PCR of nuc gene
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17
Q

What happens to a catalase positive bacteria if it is placed on a slide with H2O2?

A

It will bubble within 1-3 seconds

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18
Q

What are the indicators of highly pathogenic species?

A
  • coagulase +
  • hemolysis
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19
Q

What will you see in a sample that is coagulase +?

A

The fluid will be cloudy

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20
Q

What does a VP test, test for?

A

Acetonin production

+ will be red

  • will be yellow
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21
Q

What does a beta- galactosidase test, test for?

A

Called lactase test/ Looks to see if the bacteria ferments lactose.

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22
Q

What strains of staphylococcus is typically in pets?

A

S. scleiferi (beta hemolysis +, VP positive, trehalose negative)

S. Pseudointermedius ( trehalose positive , VP negative, Beta hemolysis +)

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23
Q

What strains of staphylococcus are emerging?

A

S. felis ( Coagulase negative, VP negative, Lactase positive)

S. Chromogenes (Coagulase negative, VP negative, Lactase negative)

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24
Q

Which staphylococcis strains are more pathogenic?

A

Coagulase positive strains are more pathogenic particularly strains with beta-hemolysis
ie. s aureus, s. schleiferi, s. pseudointermedius, s. delphini

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25
Q

What coagulase positive staphylococcus is seen in humans?

A

S. Aureus

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26
Q

What is the normal habitat of staphylococcus?

A

• Normal commensal of:
r1. skin of mammals & birds
2. tubular orifices in animal body:
✓ Nasal cavity: e.g. 20-40% of the population carry it

✓ Buccal cavity

✓Naso-pharynx

✓ Mammary gland

✓ Groin region

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27
Q

What are the major risk factors of staphylococcal diseases?

A

Opportunistic pathogen ……. waiting for some of the following stressors
1. Linked to parasitic, fungi, and viral infections
✓ Tick (Ixodus ricinus) infestation ✓ Sarcoptic mange and lice infestation ✓ Skin vesicles caused by a virus (such as parvovirus or pox virus …) ✓ Mycotoxin infections

  1. Shearing in sheep
  2. Hair-cut in dogs
  3. Nutritional imbalance (zinc, vitamin deficiency)
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28
Q

What are the 3 virulence factors for staphylococcus?

A

A. Body structures for adhesion & binding

B. Enzymes
C. Toxins

29
Q

What cell structures are important for adhesion and binding?

A
  1. Cell wall – useful for bacterial viability, homeostasis, protect the bacteria
    from attack by host lysozyme
  2. protein A - bind Fc of IgG protects, blocks immune response, & opsonization
  3. binding or clamping factors – attachment to host proteins
  4. Capsule (slime layer) – useful for
    ✓ adhesion
    ✓ prevents chemotaxis and
    ✓ inhibit phagocytosis by polymorphonuclear leukocytes
30
Q

In staphylococcus, why is the capsule important ?

A

When bacteria invade and get inside cell they release chemokines. This signals for all the immune cells to come to that site. Like hey come get him. This causes chemotaxis of leukocytes which increase cardiac output and perfusion (inflammatory) so alot of blood flow/ macrophages come to the site.

In staphylococcus its capsule prevents the transmission of chemokines, and this lets the bacteria silently invade without causing chemotaxis. This capsule also will inhibit phagocytosis. It makes the bacteria undigestible and bacteria will remain alive within macrophage.

31
Q

In staphylococcus, why is protien A important ?

A

Normally antibodies on the surface of the cell will grab onto the bacteria and invite complement to come to destroy it. Protien A turns the arms away so it cant grab the bacteria.

2. protein A - bind Fc of IgG protects, blocks immune response, & opsonization

32
Q

What are the enzymes involved in invasion of the cell for staphylococcus?

A

B. Enzymes for invasins
1. hyaluronidase - breaks down connective tissue between adjacent cells
(digs deeper between cells)

  1. catalase – protects against host reactive oxygen species (ROS) e.g. H2O2
  2. coagulase - clots blood to hide in it
  3. staphylokinase - lyses clots (fibrin) to come out of it and disperse itself
  4. lipase - digest lipids, thus allows to colonize skin surface & sebaceous
    glands
  5. protease - destroys tissue proteins
  6. beta-lactamases - inactivate beta-lactam drugs’ thus, survive treatment
33
Q

What are the toxins used for pathogenicity for staphylococcus?

A

C. Toxins

  1. hemolysin (alpha, beta, or gamma) - destroys red blood cells, neutrophils, macrophages, platelets
  2. cytolytic toxins (leukocidin)- destroy cell membranes of host cells (leukocytes)
  3. exfoliative toxin – separate skin layers, resulting in impetigo & skin layer peel off
  4. toxic shock syndrome (TSS) toxin – causes
    a. shock &
    b. superantigens (Mass T cell activation i.e. 20% of all body T cells)
  5. enterotoxins – 20 toxins in total. They cause
    a. food poisoning by stimulating the gut motility (vomiting) &
    b. superantigens
34
Q

What occurs durring toxic shock for staphylococcus?

A
  1. ) Sends toxin that will widen blood vessels at the level of capillary.
  2. ) Blood pools at level of the tissues and is not returning to the heart.
    - hypovolemia
  3. ) Superantigens will stimulate T cells. It stimulates 20% of T cells which is a huge immune response ( normally like 0.0001 -0.001% of T cells are activated at any time) and its like a house on fire. The immune system is overstimulated and begins to destroy own tissues.

T cells ready to fight and we are the battle field.

-

35
Q

What are the steps in staph pathogenesis ?

A
  1. ) Adhesion and attachment on the host cell surface or to matrix between each cells,
  2. ) Biofilm formation on host cell surface for persistence.
  3. ) Some bacteria advance for intracellular invasion, multiplication & persistence in the host cell.
  4. ) ellicit inflammation, abcess formation, necrosis, & bacteria encapsulation
  5. )a. Bacteria hide in dormant small colony varient (SCV) form in the sequestra.
    b. ) Abcess matures, ruptures, bacteria spreads via blood stream.

Blood pumps to heart taking bacteria with it. This casues endocarditis, next it goes to the brain (20% cardiac output) then to kidney, then to liver, ect.

36
Q

What organs are likely to become infected with bacteremia?

A

✓ Organs that receive higher cardiac output most likely get infected
✓ These organs include endocardium, lung, meninges, liver, kidney, uterus, bones, joints

37
Q

What are the 4 coagulase positive staphylococci?

A

S. aureus – mammals & birds

S. hyicus – pigs
S. pseudointermedius - pets
S. schleiferi - pets

38
Q

What are the 3 coagulase negative staphylococci?

A

S. chromogenes – mammals

S. felis – pets
S. epidermidis – foot odor in humans due to isovaleric acid production following degradation of leucine in sweat by bacterial leucine dehydrogenase enzyme

39
Q

What are the four directions staphylococcus will advance from?

A

Staphylococcus spp. advance from four directions (cutaneous pus/abscess, ear, mammary, & urogenital)

40
Q

What are the systemic life threatening infections that can come from staphylococcus? what are the life threatening toxicosis?

A

Systemic & life-threatening infections
✓ bacteremia/septicemia ✓ endocarditis (hear valves) ✓ metritis ✓ pneumonia ✓ osteomyelitis ✓ meningitis
and
life-threatening toxicosis
✓ toxicosis by releasing diverse toxins e.g food poisoning ✓ shock (TSS)

41
Q

What is the staphylococcus disease pathogenesis range? Where does it start, what is a potential outcome?

A

scalded skin, pus/abscess, gangrene, ear/otitis, mastitis, & urogentital infections to pneumonia, endocarditis (heart valves), meningitis, osteomyelitis, & toxicosis/shock

42
Q

What can staphylococcus aureus cause in cattle?

A
  • Mastitis
  • Teat based pustules/ impetigo (>80-90% cases)
43
Q

What can staphylococcus aureus cause in sheep?

A
  • mastitis similar to cattle
  • tick pyemia of lambs
  • Dermatitis of torn skin
  • Periorbital dermatitis.
44
Q

What can staphylococcus aureus cause in goat?

A
45
Q

What can staphylococcus aureus cause in pigs?

A
  • mastitis (impetigo)
  • endometritis
46
Q

What can staphylococcus aureus cause in horses?

A
  • mastitis
  • botrymocosis of spermatic cord after castration.
47
Q

What can staphylococcus aureus cause in poultry?

A
  • septicemia
  • foot/ joints (pyogranulomatous lesion “ bumble foot”)
  • arthritis
48
Q

What can staphylococcus aureus cause in dogs and cats?

A
  • suppurative lesion similar to s. pseudointermedius
49
Q

What can staphylococcus pseudointermedius cause in dogs and cats?

A

Dogs & cats: pyoderma, pyometra, otitis externa, pneumonia, S. pseudointermedius
oseoarthritis, wound, eyelid and conjunctivits Chronic and recurrent pyoderma in juvinile and adult dogs & cats Risk factors of pyoderma: skin allergy, genetics & endocrine disorder

This is even more dangerous than staph aureus in dogs and cats.

50
Q

What can staphylococcus schleiferi cause in dogs and cats?

A

Dogs (cats): otitis externa, otitis media, head shaking or tilting, skin
reddening, hair loss, & scratching/itching, pyoderma (pus)

51
Q

What can staphylococcus felis cause in cats? Is it coagulase positive or negative?

A

Cats: otitis, abscess, dermatitis, cystitis, conjunctivitis
Coagulase negative

52
Q

What can staphylococcus chromogenes cause in Cattle? Horses & Cats? Pigs?

A

Cattle: subclinical mastitis

Pig: exudative epidermititis

Horses & cats: dermatitis (rare)

53
Q

What can staphylococcus hyicus cause in pigs? cattle? horses?

A

Pig: exudative epidermatitis (greasy pig disease) in young pigs, septicemia (fatal), septic polyarthritis (polylimb lameness), metritis, vaginitis
Cattle: mastitis
Horse: skin infection

54
Q

What Staph bacteria should you suspect first in pigs?

A

S. Hyicus

55
Q

What are signs of cutaneous presentations of staphylococcusin humans? why is this occuring? What bacteria is typically causing this?

A

Signs: Scalded skin diseases of humans (skin layers slough off; exudative epidermitis)
✓ widespread formation of fluid-filled blisters that are
thin walled and easily ruptured outer layer or membrane
✓ exfoliation (peeling of skin layers or desquamation)
due to breakdown of desmosome (macula adherens) of skin by epidermolytic exotoxins (exfoliatin)
✓ caused by S. aureus

56
Q

What are signs of cutaneous presentations of staphylococcus in pigs? why is this occuring? What bacteria is typically causing this?

A

Staphylococcus spp. – cause cutaneous pus and peeling of skin layers in pigs
Signs: greasy pig disease (Exudative epidermitis) (similar to human scalded skin disease)
✓ an acute generalized infection of suckling and weaned pigs. ✓ excess sebaceous secretion ✓ exfoliation and exudation of skin ✓ Poly limb lameness (polyarthritis) ✓ Metritis ✓ vaginitis (attacks vaginal tissue)

✓ caused by S. hyicus
✓ S. chromogenes (sometimes)

57
Q

What are signs of cutaneous presentations of staphylococcus in dogs and cats? why is this occuring? What bacteria is typically causing this? What other areas can this occur in?

A

Signs: pyoderma of dogs and cats ✓ erythema, pustule, papule, crust, scaling, epidermal collarettes, and alopecia;

✓ cats most commonly present with multiple crusted papules (“miliary dermatitis”) or erosive plaques ✓ areas affected in dogs are axillae, groin, ventral neck, ventral abdomen, interdigital spaces;

✓ in cats are the face, neck and ventrum

caused mostly by s. pseudointermedius

(by S. aureus & S. schleiferi, less common)

Signs in dogs and cats:

✓ Otittis externa,

✓ pyoderma,

✓ Pyometra

✓ by S. pseudointermedius & S. aureus

Signs: Otitis externa

✓ S. schlefieri-dog

✓ S. felis- cats

58
Q

What are signs of pus and or gangrene forming bacteria in the udder and teats? What bacteria is this caused by?

A

Signs: mastitis in ruminants

✓ chronic, acute or peracute udder ulcer (impetigo) * udder will be cold as ice and can fall off)

✓ gangrenous mastitis due to a toxin in postparturient cows

✓ caused by S. aureus
Signs: subclinical ruminant mastitis

✓ S. chromogenes

59
Q

What are the 4 major pathogens that cause mastitis?

A
  1. ) Enterobacteriaceae
  2. ) Staphylococcus ( 70-80% of cases)
  3. ) Streptococcus
  4. ) Mycoplasma
60
Q

What casues tick pyemia in sheep? What is it?

A

Staphylococci – pus forming bacteria in skin infested with ticks in sheep
Signs: Tick pyemia (i.e. the spread in the bloodstream of pus-forming bacteria released from an abscess)
✓ common in lambs of 2-5 weeks if heavily infested with Ixodes ricinus ✓ chronic, acute and peracute. ✓ caused by S. aureus

61
Q

What causes mastitis and botrymycosis in horses?

A

Staphylococci – pus & nodule forming bacteria in skin of lips/limbs, udder/scrotum, & septicemia in horses

Signs: mastitis and skin botryomycosis in horse (botry = cluster of grapes) ✓ nodules on lips, limbs, scrotum ✓ multifocal/widespread papules/pustules. ✓ May have cutaneous and/or visceral involvement ✓ Scrotum infections after castration in male horses

✓ caused by S. aureus

62
Q

What causes bumble foot in poultry?

A

Staphylococci – pus forming bacteria in joints of leg/ foot/wings, gangrene of the skin, and septicemia
Signs: Bumble foot in poultry ✓ A pyogranulomatous process of subcutaneous tissue of foot & the joints ✓ arthritis and septicemia in turkeys ✓ omphalitis – yolk sac infection, wing rot or gangrenous dermatitis infection in poultry ✓ caused by S. aureus

63
Q

What fluids can you test for staphylococcus? What determines where your sample is from? What media?

A
  • Fluids you can test will be dependent on the location of the infection.

What can you test: Pus, nasal secretions, urogenital secretion, milk, joint fluid, blood

Media: Manitol salt agar and purple agar base with 1% maltose

64
Q

What is the treatment and control methods for staphylococcus? What antimicrobials is it well known for being resistant to?

A

Staphylococcus consists multi-drug resistant species
✓ E.g. Staph. aureus is a member of the 6 gangs (ESKAPE).

• Staph. aureus is well known globally for acquiring resistance to the following
two antimicrobials
1. Methicillin resistance

  1. Vancomycin resistance

Staph aureus is a MRSA

65
Q

What ways can you control and prevent staphylococcus infections in general? How can you do this?

A

✓ Improve the immunity, feeding, and hygiene of each animal & its house/barn
✓ Lambs – tick control by pour-on or dipping in acaricide periodically
✓ Proper cleaning of wounds and surgical openings
✓ Carefully perform shearing in sheep, hair-cut in dogs

66
Q

What ways can you control and prevent staphylococcus infections in dairy animals ? How can you do this?

A
  1. The fundamental control is good hygiene at milking time.
    ✓ a. Single use paper towels to dry teats.
    ✓ b. Milkers should wear gloves.
    ✓ c. Teat dip after milking (1% Iodine) 2. Dry cow therapy at drying off. ?
  2. Separate all infected/positive cows. 4. Cull cows if they remain clinical or cows with chronic mastitis 5. Prevent reinfection into the herd.
    ✓ Culture to test for positivity all purchased cows before mixing to the herd.
67
Q

What bacteria is similar to staphylococcus in terms of its habitats? What are its virulence factors/ methods of attacking the host?

A

✓ Like Streptococcus, Staphylococcus is an inhabitant of:
▪ skin, mucus membrane of mouth, nose, ear canals, and mammary gland
▪ Advance/spread from these primary sites to all body systems/generalized ✓ Both bacteria genera express diverse virulence factors such as:
▪ surface structures, enzymes, and toxins
▪ Use these weaponry for causing pus and abscess initially on the skin and soft
tissues followed by systemic infections and toxicosis/shock

68
Q
A

Bacteriology/ Mycology (19 decks)

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