Bacteriology - Test Ii Lecture (4-6)

Front 1

What is a distinctive feature of mycobacterium? (think stains)

Back 1

don't gram stain

Front 2

What is the morphology of mycobacterium?

Back 2

gram pos rod

Front 3

What are the 3 rules of thumb for gram positive rods?

Back 3

(1) less frequently isolated, but cause important diseases
(2) tend to cause syndromes therefore history, signalment and clinical signs often give a presumptive diagnosis
(3) if a more difinitive diagnosis is needed, morphology is VERY helpful

Front 4

What are two species of myobacterium that are of particular importance to us?

Back 4

M. bovis and M. avium ss paratuberculosis

Front 5

What atmospheric environment does mycobacterium live in?

Back 5

strict aerobe

Front 6

What is unique about the cell wall of myobacterium spp?

Back 6

lipid rich cell wall with mycolic acids therefore can use an acid fast stain

Front 7

What is the pathology of mycobacterium infections?

Back 7

granulomatous or pyogranulomatous

Front 8

Where do mycobacterium survive?

Back 8

survive and multiply intracellularly in mononuclear phogocytes

Front 9

What are mycobactrium resistant to?

Back 9

disinfectants, antibodies, acid, and desiccation

Front 10

How are mycobacteria classified? What are these two main categories?

Back 10

-classified by where they live
-classified as (1) obligate parasites and (2) saprophytic mycobacteria

Front 11

What are the obligate parasite Mycobacteria and what does this mean?

Back 11

--M. tuberculosis and M. bovis
-they do not multiply outside of their vertebrate hosts
-they are also obligate pathogens

Front 12

What are the obligate parasite mycobacteria?

Back 12

obligate pathogens

Front 13

What are the saprophytic mycobacteria? how are they further divided? what does this mean?

Back 13

(1) facultative opportunistic pathogens =sporadically cause disease (M. avium complex, and M. intracellulare)

(2) environmental saphrophytes = almost never cause disease (M. phlei)

Front 14

Do OBLIGATE parasites shed by infected animals survive in the environment?

Back 14

YES!

Front 15

Can nonpathogenic species of mycobacteria cause disease?

Back 15

yes - in immunocompromised individuals

Front 16

What four virulence factors do mycobacterium have?

Back 16

(1) Cord Factor
(2) ability to survive and replicate in tissue
(3) superoxide dismutase
(4) mycobactins and exochalins

Front 17

What does cord factor, one of the 4 virulence factors of mycobacteria do?

Back 17

-inhibits chemotaxis
-leukotoxic

Front 18

How are mycobacterium able to survive and replicate in tissue marcrophages? (one of their four virulence factors?

Back 18

(1) glycolipids-prevents macrophage activation by INF gamma
(2) sulfatides (glycolipids) - inhibits phagolysosome
(3) sulfolipids - prevent phagosomal-lysosomal fusion

Front 19

What are mycobactins and exochalins (one of the four virulence factors of mycobacterium) use for?

Back 19

iron acquisition

Front 20

What are the two types of lesions observed with mycobacterium infections and where do they most often occur?

Back 20

(1) caseous necrosis - common in the LUNGS

(2) granulomas - common in the LYMPH NODES

Front 21

What diseases are caused by obligate mycobacterial parasites?

Back 21

(1) TB
(2) Johnes disease in ruminants
(3) Leprosy
(4) Feline Leprosy

Front 22

What are the routes of infection for M. bovis infections?

Back 22

(1) inhalation of aerosols -> lung lesions
(2) ingestion of contaminated feed, water, milk
(3) ingestion of sputum -> GI infection
(4) wound infection -> rare
(5) congenital

Front 23

What is the reservoir for M. bovis infections and what predisposes animals to acquiring infections?

Back 23

TB animals - crowding, stress and genetic factors predispose animals to getting infection

Front 24

Why is eradication of M. bovis so difficult?

Back 24

-there are a variety of reservoirs that maintain the organism (in US-> dairy cattle and wildlife(white-tailed deer)

-US most states are free except MI, MN, IN, NM, CA

Front 25

How do we reduce the public health risk of bovine TB caused by M. bovis?

Back 25

(1) pasteurization of milk
(2) diagnosis, control and eradication of bovine TB (TB skin test with PPD antigen, abattoir surveillance)

Front 26

How is M. bovis (bovine tuberculosis ) diagnosed/controlled?

Back 26

TB tests by TB accredited vet
-delayed hypersensitivity test following inoculation with a purified protein derivative (PPD)

Front 27

What are the two types of TB tests used to find M. bovis infections?

Back 27

(1) Intradermal test -comparative cervical tuberculin test (CCT)
(2) Intrapalpebral test - not in US

Front 28

What do you do if you get a hard swelling >5mm at 72 hours after an intradermal test on the caudal tail fold?

Back 28

-the cow is positive so you repeat in the neck and compare with PPD of M.avium on the other side of the neck. IF the reaction is >4mm than the size of the M. avium side, the cow is a reactor and you must REPORT it!

Front 29

There are three outcomes to a TB test - what are they and which ones are reportable?

Back 29

(1) negative
(2) suspect - REPORT!
(3) reactor - REPORT!

Front 30

When might an animal show a false negative for a TB test?

Back 30

in advanced cases - therefore must diagnose by clinical signs

Front 31

AS the eradication efforts proceed with M. bovis (TB), what happens to false positives?

Back 31

proportion increases

Front 32

How do you treat/control M. bovis infections in humans and companion animals?

Back 32

-treated for 6-9 months with one set of antimicrobials (isoniazid in combo with another) and then switched to another combo
-monitored for three years
-vaccine (oral) is available (BCG), but NOT used in the US for at all

Front 33

How do you treat/control M. bovis infections in farm animals?

Back 33

cull!
-treatment in NOT an option

Front 34

What disease does M. avium ss. paratuberculosis cause?

Back 34

Johnes Disease

Front 35

What bug causes Johnes disease?

Back 35

M. avium ss. paratuberculosis

Front 36

How is M. avium ss. paratuberculosis aquired?

Back 36

-transmission by ingestion of feed and water contaminated with Johne's-positive feces

Front 37

How long is the incubation period for Johnes Disease?

Back 37

Long incubation - neonatal/juvenile exposure, disease seen in cows 2-3 years of age (NOT older than 5)

Front 38

What species does Johnes Disease affect? where?

Back 38

all ruminant species world-wide
-NO eradication program in the US (unlike M. bovis)

Front 39

What are the clinical signs of Johne's Disease?

Back 39

-progressive, persistent, granulomatous enteritis and severe, chronic diarrhea leading to emaciation and death

Front 40

What disease might have a link to Johnes Disease?

Back 40

Crohns disease in man

Front 41

In Johnes Disease, what does the GI tract look like?

Back 41

-thickened and sclerotic intestinal wall
***infiltration of intestinal wall with epitheloid cells (b/c of accumulation of macrophages that contain masses of acid fast rods)
-associated lymph nodes enlarged
-intracellular clumps of bacteria

Front 42

Are other organs affected (other than GI) by Johne's Disease?

Back 42

rarely - uterus, udder, genitalia of bulls

Front 43

What is a hallmark of Johne's Disease microscopically?

Back 43

***infiltration of intestinal wall with epitheloid cells (b/c of accumulation of macrophages that contain masses of acid fast rods)

Front 44

How do you diagnose M. paratuberculosis infections?

Back 44

-history and clinical signs
-acid-fast stain of fecal smears
-rectal scrapings and biopsy
-fecal culture - isolation and ID
-ID
-DNA probes
-serology
-immunity tests

Front 45

What is the best way to ID M. paratuberculosis?

Back 45

Fecal culture: isolation and ID
-MOST reliable, but slow!
-THEREFORE, better test are needed

Front 46

How do you treat M. paratuberculosis infections?

Back 46

you don't - cull animal

Front 47

How do you control M. paratuberculosis infections?

Back 47

-problematic
-test and slaughter sub-clinical animals
-hygiene and husbandry

Front 48

What are three diseases caused by saprophytic mycobacteria in IMMUNOCOMPETENT HOSTS?

Back 48

(1) canine leproid granuloma syndrome
(2) panniculitis syndrome in cats and dogs
(3) misc. localized mycobacterial infections

Front 49

Where are canine leproid granulomas most often found?

What breeds are predisposed?

Back 49

head and ears as a single or multiple nodules

-short coated breeds esp. Boxers (low temp growth)

Front 50

How do you diagnose canine leproid granulomas?

Back 50

-cytology/histology
-CAN'T culture the organism in vitro

Front 51

How do you treat canine leproid granulomas?

Back 51

-lesions are typically self-curing, but if REFRACTORY, respond to rifampicin/clarithromycin

Front 52

When do canine granuloma lesions tend to ulcerate (go from nodular to ulceration)?

Back 52

just before spontaneous resolution

Front 53

Where are mycobacterium that cause panniculitis syndrome in cats normally seen in the animal?

Back 53

-in inguinal fat pads of cats (survive in macrophages), therefore obese animals are predisposed
-subcutis of chest wall in dogs

Front 54

Who is disposed to panniculitis syndrome caused by a saprophytic mycobacterium?

-how is the bacteria introduced into the animal?

Back 54

fat cats

-follows trauma that penetrates fatty tissue and where dirt contaminates the wound

Front 55

How is panniculitis syndrome in cats diagnosed?

Back 55

-FNA/biopsy -> cytology and culture (takes 3-7 days to grow)
-sample intact lesion
-tell lab what you suspect

Front 56

How do you treat panniculitis syndrome in cats?

Back 56

(1) antibiotics - do culture and susceptibility first
-try doxycycline and fluroquinolones
(2) surgery

Front 57

What must you do first before treating a cat with antibiotics for panniculitis syndrome?

Back 57

-culture ans susceptibility - not predictably susceptible

Front 58

What is the morphology of E. coli (and other Enterobacteriacea)?
-oxidase status

Back 58

-gram negative rods
-oxidase negative

Front 59

What family are E. coli part of?

Back 59

Enterobacteriaceae family

Front 60

What environmental conditions do Enterobacteriaceae live in?

Back 60

FA
-grow on blood agar produces similar colonies

Front 61

The fact the Enterobacteriaceae grow on MacConkey's agar tell you what?

Back 61

-bile salt tolerance
-lactose fermentation

Front 62

What bacteria are lactose fermentors?

Back 62

-E.coli
-Klebsiella
-Enterobacter

Front 63

What bacteria are non-lactose fermentors?

Back 63

-Proteus
-Salmonella
-Yersinia

Front 64

Enterobacteriaceae are what type of bacteria?

Back 64

-Gram negative rods
-oxidase negative

Front 65

Are E.coli good pathogens or poor?

Back 65

GOOD!

Front 66

What kind of pathogens are Klebsiella, Proteus, Yersinia, and Enterobacter?

Back 66

intermediate pathogens

Front 67

What kind of pathogen is Salmonella?

Back 67

Good Pathogen

Front 68

Where do E.coli live?

Back 68

-the lower ileum and LI of most vertebrates (hours after birth)

Front 69

What type of bacteria are the most prevalent in the GIT?

Back 69

anerobes

Front 70

Can E. coli survive in the environment?

Back 70

YES! makes coliform counts valuable indices of fecal contamination

Front 71

How do animals acquire E. coli infections?

Back 71

-infections may be endogenous or exogenous
-ENTERIC infections are usually EXOGENOUS

-NON-ENTERIC infections are usually ENDOGENOUS (canine pyometra)

Front 72

Why do bitches develop pyometra?

Back 72

-due to an ascending infection of E. coli which is transient in the vagina.

Front 73

Are all strains of E.coli virulent?

Back 73

NO

Front 74

What are general virulence factors of E. coli?

Back 74

(1) attachment
(2) avoidance of phagocytes
(3) cellular toxicity
(4) systemic effects

Front 75

How do NON-ENTERIC E. coli cause infection?

Back 75

(1) attachment = pili or adhesins
(2) avoidance of phagocytes = capsule; O somatic antigens
(3) cellular toxicity = hemolysins (leucotoxins)
(4) systemic effects (ENDOtoxin)

Front 76

What are the four main diseases caused my non-enteric E.coli?

Back 76

(1) reproductive tract infections
(2) cystitis in dog
(3) mastitis in sows ans cows
(4) Colibacillosis in BIRDS

Front 77

What different type of reproductive tract infections are caused by non-enteric E. coli?

-what animals

Back 77

-pyometra
-endometritis
-abortion
-prostatitis

-in a variety of animals

Front 78

What is canine pyometra secondary to in the dog?

Back 78

cystic endometrial hyperplasia in response to prolonged exposure to progesterone THEREFORE - the bacteria is opportunistic

Front 79

What is the role of progesterone in canine pyometra?

Back 79

-causes fluid accumulations in the uterine lumen and decreases myometral activity (down-regulates the immune system)
-enables E. coli to bind to the endometrium more effectively

Front 80

What phase of the canine cycle does canine pyometra occur in?

Back 80

-luteal phase (diestrus) or after administration of progestins

Front 81

What bacteria is usually first to invade the compromised uterus?

Back 81

E.coli, but strict anerobes often invade and may be the only bacteria isolated if it is a chronic infection

Front 82

What other clinical signs might be associated in a dog with pyometra?

Back 82

PU/PD
-immune complex glomerulonephritis (proteinuria)
-mild interstitial and tubular nephritis

Front 83

What is the cause of PU/PD in canine pyometra?

Back 83

E. coli endotoxin interferes with the action of ADH on renal tubules

Front 84

E. coli is isolated in what percentage of cases of dogs with cystitis?

Back 84

37-45%

Front 85

When does mastitis caused by E. coli commonly occur in cows and sows?

Back 85

around the time of parturition/peak production b/c the environment in a source of infection

Front 86

Can mastitis lead to death in an E. coli infection?

Back 86

yes - absorption of endotoxin leading to toxemia and death

Front 87

What is the route of infection of colibacillosis in birds?

Back 87

-GIT or respiratory tract

Front 88

If you ID E. coli in a fecal sample, does this mean that it is the cause of the disease?

Back 88

NO
-E. coli is part of the normal flora
-not all STRAINS of E. coli are capable of causing disease
-must demonstrate strain is capable of causing disease (has the right virulence factors)

Front 89

What two virulence factors are important in enteric diseases caused by E. coli

Back 89

(1) pili
(2) Enterotoxin

Front 90

What do pili (a virulence factor of E. coli) do to cause enteric diseases?

Back 90

-attach E. coli to specific receptor sites on enterocytes (required for disease production)
-pili are specific for cell surace receptors, which differ between sites in the body and species of animals

Front 91

What is required for enteric diseases caused by E. coli?

Back 91

-attachment of pili to enterocytes
-bacteria do NOT invade

Front 92

What is another name fore E. coli diarrhea?

Back 92

colibacillosis

Front 93

In colibacillosis, what type of enterotoxins are involved?

Back 93

cytotonic enterotoxins

Front 94

Do cytotonic enterotoxins cause damage to cells of the intestinal wall?

Back 94

NO - therefore DO NOT cause inflammation

Front 95

What are E. coli producing cytotonic enteroxins also called?

Back 95

Enterotoxigenic E. coli = ETEC

Front 96

What are the two types of cytotonic enterotoxins involved in colibacillosis?

Back 96

(1) heat labile (LT)
(2) heat stable - MOST common!

-but both have the same outcome = NET loss of electrolytes

Front 97

What is the net effect of cytotonic enteroxins involved in colibacillosis?

-what is the result of this?

Back 97

NET loss of electrolytes
-Cl is excreted and NaCl in not absorbed

-THIS causes a net efflux of water

Front 98

What do ETECs cause?

Back 98

hypersecretory diarrhea

Front 99

How do you diagnose colibacillosis?

Back 99

you wouldn't - treat empirically based on age and type of diarrhea

Front 100

What type of diarrhea do ETECs produce?

Back 100

watery

Front 101

If you REALLY wanted to diagnose Colibacillosis, what would you do?

Back 101

multiplex PCR for fimbriae and enterotoxin genes

Front 102

What is a major disease caused by ETEC?

Back 102

pre-weaning diarrhea in neonatal calves, lambs and piglets

Front 103

Pre-weaning diarrhea caused by ETECs is a result of what three factors?

Back 103

(1) bacterial factors - pili, enterotoxin, numbers
(2) host factors - age, immunity
(3) environmental - overcrowding, wet/dirty, high numbers of bacteria

Front 104

What is important about age and the ability to get colibacillosis?

Back 104

-receptors for pili are only in the first week of life

Front 105

What is important in controlling pre-weaning diarrhea caused by ETECs?

Back 105

-management! because overcrowding, wet/dirty babies causes increased susp. to babies

Front 106

What is another name given to colibacillosis of calves?

Back 106

white scours

Front 107

What is post-weaning diarrhea caused by?

Back 107

ETEC + EHEC + EPEC

Front 108

Why does post-weaning diarrhea occur at weaning?

Back 108

-loss of Ab from milk and waning of passive transfer immunity
-change of diet

Front 109

Is Edema disease of pigs an enteric or non-enteric syndrome?

Back 109

enteric

Front 110

When does edema disease of pigs occur?

Back 110

6-14 weeks of age - grower or weaner pigs

Front 111

What type of E. coli is edema disease of pigs caused by and what does it produce?

Back 111

-hemolytic, NOT invasive E. coli
-produce ANGIOTOXIN (vasotoxin = Shiga-like toxin)

Front 112

What causes the edema in edema disease in pigs?

Back 112

-the angiotoxin is absorbed into the blood stream and causes damage to endothelial cell walls

Front 113

What form of E. coli is of concern to humans?
Why?

Back 113

EHEC - ruminants are carriers

-causes Heamolytic Uremic Syndrome (HUS) in 5-10% of cases

-think spinach and undercooked burgers!