Non-spore forming anaerobes

Question 1

Non spore forming anaerobes

Answer 1

-Fusobacterium
-Dichelobacter
-Prevotella
-Bacteroides

Question 2

Characteristics of non spore forming anaerobes

Answer 2

-gram negative,
-obligate anaerobes
-involved in necrotic and suppurative conditions
-often polymicrobial
-many require special skills in handling due to sometimes easy death due to oxygen exposure
-stink!!

Question 3

Physical characteristics of different non spore forming anaerobes

Answer 3

Fusobacterium: long, slender, pleomorphic gram negative

Dichelobacter: straight or slightly curved gram negative rods with swellings at both ends

Prevotella: gram negative coccobacilli with rounded ends

Question 4

Natural host of habitat

Answer 4

Often part of normal microbiota
>Fusobacterium= lives in GI tract
>Dichelobacter= main resident of ruminant foot
>Prevotella= resident of mouth of many specie s

Opportunistic pathogens
*issue when then gain entry into normal sterile sites resulting in ischemic tissues

Question 5

Clinical treatment

Answer 5

more dependent on the site of infection for treatment rather than the exact ID of pathogen

Question 6

Taxonomy

Answer 6

Short rods: prevotella and dichelobacter

Long rods: fusobacterium

**ID by MALDI-TOF

Question 7

Virulence factors of fusobacterium

Answer 7

-Have leukotoxin (lysis of bovine leukocytes, and toxic for hepatocytes)

Question 8

Virulence factors for Dichelobacter nodosus

Answer 8

1. Type IV fimbriae= motility and adherence
2. Serine proteases= degradation of hoof proteins

Question 9

F. necrophorum in cattle presentations

Answer 9

-causes calf diptheria (necrotic laryngitis), liver abscesses, interdigital necrobacillosis (footrot), metritis (dairy cattle)

Question 10

F. necrophorum associations in cattle

Answer 10

-often associated with Trueperella pyogenes

Question 11

F. necrophorum in cattle causing calf diptheria

Answer 11

Necrotic foci on the larynx, trachea, and buccal cavity
-abrasions of pharynx due to rough feed providing entry
-can lead to fever, depression, excessive salivation
-foul smell
-progressed to fatal pneumonia if untreated

Question 12

F. necrophorum in cattle causing liver abscesses

Answer 12

-Seen in feedlot cattle
-results in septic embolism following rumenitis (due to friable material of liver)

Question 13

F. necrophorum in sheep

Answer 13

-causes foot abscesses

Question 14

D. nodosus in sheep

Answer 14

-causes contagious foot rot= abscesses
-results in lameness
-primary reservoir is infected sheep (transmission via transiently contaminated environments- trucks and paddocks)
**bacteria does not survive well in environment

Question 15

Mechanism of D. nodosus in sheep

Answer 15

1.Damage to tissues (interdigital skin is delicate, can become mascerated when wet)

2. Initial invasion by F. necrophorum (superficial infection and inflammation)
3. D. nodosus arrives (proliferates in F. necrophorum lesion)
4. D. nodosus produced proteases which detach horn from underlying tissues allowing for further invasion of F. necrophorum

Question 16

D. nodosus in goats, cattle, pigs

Answer 16

-causes interdigital infections

Question 17

Prevotella and porphyromonas species in cattle

Answer 17

causes interdigital necrobacillosis

Question 18

Prevotella and porphyromonas species in dogs and cats

Answer 18

-causes periodontal disease

Question 19

Sample collection

Answer 19

**difficult because they are part of normal microbiota

-purulent material from abscesses
-discharges
-tissue specimens

Question 20

Sample handling

Answer 20

-anaerobic swabs are a must
-larger chunks of tissue can be useful in maintaining anaerobic microenvironments (because inside not as exposed to O2)

Question 21

Lab ID

Answer 21

1. smears (use dilute carbol fuchsin better than gram stain)
2. Anaerobic culture
   -blood agar with special supplements for anaerobes
   -media must be pre-reduced
   -MALDI pretty good except for fuso
3. PCR ID (culture independent)

Note: susceptibility testing of anaerobes is poorly standardized

Question 22

Lab collection jar components

Answer 22

1. Anaerobic jar- air tight
2. Gas pack- oxygen scavenging sachet (each one specific for certain atmosphere)
3. Anaerobic indicator strip- identifies O2
4. Pre-reduced media- store anaerobically to dissolve O2

Question 23

Zoonosis: Streptobaccilus moniliformis

Answer 23

-order Fusobacteriales
-spirillum moniliformis is microaerophilic
-found in rodents; 7-10 day incubation period
>Rat Bite Fever= can lead to fever, chills, headache, vomiting, macropapular rash
>systemic spread, bacteremia, endocarditis may occur

-people at risk: homeless people or people working with animals

Question 24

Zoonosis: Capnocytophaga canimorsus

Answer 24

-unrelated to todays organisms
-gram negative rods
-slow growing and fastidious
-organisms within this genus are carboxyphilic
-found in mouths of healthy cats and dogs, humans… can lead to infections from bites

Question 25

Infections from Capnocytophagia canimorsus

Answer 25

-commonly occur in older and immunocompromised individuals.. especially when splenectomised
>without spleen, bite not even needed.

-mortality rate up to 30% (meningitis, endocarditis, sepsis)

-bacteria continues to replicate, and kill host cells even when phagocytosed

Question 26

Antimicrobials critical for capnocytophaga canimorsus

Answer 26

-Vancomycin
-Clindamycin
-erythromycin
-rifampin
-penicillins

Question 27

Treatment options

Answer 27

Treatment depends on site of infection
-combination of systemic antimicrobials and topical antiseptics

**managment paractices iportant= dietary management, paddock and pasture management to keep feet clean and dry

Question 28

Drugs to avoid for non spore forming anaerobes

Answer 28

1. Penicillins EXCEPT F. necrophorum
2. Penicillin and colistin when working with Bacteroids spp
3. Capnocytophagia- avoid sulfonamides and aminoglycosides

Question 29

Macropapular

Answer 29

a cutaneous eruption consisting of both mascules and papules

Question 30

Mascules

Answer 30

patch of skin that is altered in colour but not elevated