Microbiology Of Enteritis Flashcards
What are the common sites for commensals?
Define commensals
The relationship between two species whereby one (the commensal) benefits from the association, whereas the other neither benefits nor suffers. Not restricted to bacteria (fungi and protozoa).
What will GI commensals cause if they are given the opportunity?
Disease
Name 2 common gram negative anaerobic rod commensals (3)
Bacteroides sp.
Desulfomonas sp.
Fusobacterium sp.
Name 3 common gram negative faculative anaerobic/aerobes rod commensals (6)
Enterobacteriaceae
Escherichia coli
Citrobacter freundii
Klebsiella sp.
Enterobacter sp.
Proteus
Name a common gram positive faculative anaerobic/aerobes rod commensals
Lactobacillus
Name a common gram positive faculative anaerobic/aerobes cocci commensals (3)
Streptococcus
Staphylococcus
Enterococcus
Name 3 gram positive commensals which are anaerobic rods (5)
Bifidobacterium
Clostridium
Eubacterium
Lachnospira
Propionobacterium
Name 3 gram positive commensals which are anaerobic cocci (4)
Rumonococcus
Peptococcus
Streptococci
Coprococcus
Commensal can be a flexible term, Campylobacter is an example of this - explain why
- Campylobacter is a commensal of a number of species and will be found if looked for.
- Causes disease in some species ‘man’ ‘Dogs’ other?
- Adaptive resistance may lead to a carrier/commensal state of some organisms ‘Campylobacter in man’ in dogs?
- True commensals in poultry, pigs, cattle?
- Due to high prevalence in asymptomatic species it is hard to attribute to disease.
What can adaptive resistance lead to?
carrier/commensal state of some organisms
Cattle:
A) Name 3 GI bacterial Pathogens (4)
B) Name 3 viral GI pathogens (4)
A)
- Escherichia coli
- Salmonella Serotypes
- Mycobacterium avium
- Clostridium perfingens types B&C
B)
- Rotavirus
- Bovine Coronavirus
- BVDV
- Rinderpest virus (eradicated 2010 Not UK)
Sheep/goats:
A) Name 2 bacterial GI pathogens (3)
B) Name a viral GI pathogen (2)
A)
- Escherichia coli
- Salmonella Serotypes
- Clostridium perfingens types B&C
B)
- Rotavirus
- Pestes des petis ruminant virus (not UK)
Pigs:
A) Name 3 bacterial GI pathogens (5)
B) Name 3 viral GI pathogens (4)
A)
- Escherichia coli
- Clostridium perfingens types A&C
- Brachyspira hyodysenteriae and others
- Lawsonia intracellularis
- Salmonella Serotypes
B)
- Rotavirus
- Transmissible gastro enteritis virus
- Classical swine fever virus
- African Swine fever virus
Horses:
A) Name 4 bacterial GI pathogens (6)
B) Name a viral GI pathogen (1)
A)
- Salmonella Serotypes
- Clostridium perfingens types A&C
- Clostridium difficile
- Ehrlichia risticii (Non UK mostly US)
- Actinobacillus equuli
- Escherichia coli (role unclear)
B) Rotavirus
Cats/Dogs:
A) Name 6 bacterial GI pathogens (8)
B) Name 3 viral GI pathogen (4)
A)
- Salmonella sp.
- Campylobacter sp.
- Clostridium difficile
- Clostridium perfringens
- Yersinia
- Bacillus piliformis
- Escherichia coli
- Aeromonas hydrophila
B)
- Parvovirus
- Rotavirus
- Coronavirus
- Canine distemper virus
Poultry:
A) Name 4 bacterial GI pathogens (5)
B) Name 3 viral GI pathogen (5)
A)
- Salmonella
- Salmonellosis
- Salmonella
- Fowl typhoid
- Clostridium perfringens
- Necrotic enteritis
- Brachyspira pilosicoli, intermdia
- Yersinia
B)
- Adenovirus
- Coronavirus
- Birna virus
- Reovirus (role unclear)
- Rotavirus
Enterobacteriaceae:
A) Gram?
B) Respiration type?
C) Are they motile?
A) NEgative
B) Faculative anaerobe
C) Motile
What will enteric bacteria tolerate in selective media?
Bile salts
Where do Enterobacteriaceae grow?
Non enriched media
Enterobacteriaceae:
A) Oxidase?
B) Catalase?
C) What can they ferment?
D) What can they reduce?
A) -ve
B) +ve
C) Glucose
D) Nitrate
Enterobacteriaceae:
Name 2 manjor enteric pathogens (3)
- Escherichia coli
- Salmonella serotypes
- Yersinia sp.
Enterobacteriaceae:
Name 2 oppurtunisitic pathogens (3)
- Proteus
- Enterobacter
- Klebsiella
Can we differentiate on culture?
They all look pretty much the same
How can we differentiate on morphology? (3)
- Lactose fermentations (MacConkey/ XLD)
- Reactions on selective media (XLD/BG)
- Eosin-methylene blue agar for E. coli (metallic sheen)
How can we look at colonial morphology? (3)
- Mucoid – Klebsiella, Enterobacter
- Proteus swarming on rich media
- Serratia marcescens red pigmentations
Ecoli:
- Clinical importance
- Culture characteristics
- Motility at 30°C
- Lactose fermentation IMViC tests:
- Indole
- Methyl Red
- Voges Proskauer
- Citrate
- H2S production on TSI
- Lysine Decarboxylase
- Urease
- Major pathogens and Commensal
- Some haemolytic
- Motile
- +
- +
- -
- -
- -
- -
- +
- -
Salmonella:
- Clinical importance
- Culture characteristics
- Motility at 30°C
- Lactose fermentation IMViC tests:
- Indole
- Methyl Red
- Voges Proskauer
- Citrate
- H2S production on TSI
- Lysine Decarboxylase
- Urease
- Major pathogen
- -
- Motile* Not all
- -
- _
- +
- -
- +
- +
- +
- -
Yersinia:
- Clinical importance
- Culture characteristics
- Motility at 30°C
- Lactose fermentation IMViC tests:
- Indole
- Methyl Red
- Voges Proskauer
- Citrate
- H2S production on TSI
- Lysine Decarboxylase
- Urease
- Major Pathogen
- -
- Motile* except pestis
- -
- V
- +
- -
- -
- -
- -
- *except pestis
Proteus:
- Clinical importance
- Culture characteristics
- Motility at 30°C
- Lactose fermentation IMViC tests:
- Indole
- Methyl Red
- Voges Proskauer
- Citrate
- H2S production on TSI
- Lysine Decarboxylase
- Urease
- Opportunist
- Swarming growth
- Motile
- -
- +/-
- +
- v
- v
- +
- -
- +
Enterobacter:
- Clinical importance
- Culture characteristics
- Motility at 30°C
- Lactose fermentation IMViC tests:
- Indole
- Methyl Red
- Voges Proskauer
- Citrate
- H2S production on TSI
- Lysine Decarboxylase
- Urease
- Opportunist
- Mucoid
- Motile
- +
- -
- -
- +
- +
- -
- +
- -
Klebsiella:
- Clinical importance
- Culture characteristics
- Motility at 30°C
- Lactose fermentation IMViC tests:
- Indole
- Methyl Red
- Voges Proskauer
- Citrate
- H2S production on TSI
- Lysine Decarboxylase
- Urease
- Opportunist
- Mucoid
- Motile
- +
- -
- -
- +
- +
- -
- +
- +
What are the E. Coli key groups? (4)
•ETEC, EPEC, VTEC Necrotoxigenic etc.
What are the cultural and microscopic properties of campylobacter?
Colonies are flat, droplet-like, glistening and tend to spread along the direction of the steak on moist agar. Older colonies become white to salmon-coloured. The colonies have a very characteristic odour.
Requires microaerophilic growth conditions (5% oxygen and 10% carbon dioxide)
Gram-negative, very slender vibrio / spiral shaped (fixed smear dead bacteria)
Two days to grow.
C. jejuni subsp jejuni causes GI infections, Who are the carriers? (5)
Carried by poultry, cattle, sheep, dogs, wild animals and birds.
C. coli causes GI infections, where can it be isolated? (2)
Isolates pigs and poultry.
C. fetus subsp fetus causes reproductive infection, what does it do in animals and which ones (2)
sporadic abortion sheep and cattle.
C. fetus subsp venerealis is a reproductive infection, what does it cause in cattle?
Abortion (STD)
What 2 things are there a correlation with with campylobacter in birds?
- reduced weight gain (only visible on large studies)
- Hock burn (which is associated with wet bedding i..e more watery faeces)
Is campylobacter a clear pathogen in dogs?
Some times it is hard to define if a bacteria causes disease in an animal. Diarrhoea in dogs and other domestic animals has been attributed to Campylobacter species but Campylobacter is often found in healthy animals.
In older dogs the evidence is unclear for campylobacter causing diarrhoea but there is some evidence in puppies. In an open screen ca. 25% of dogs were found to carry Campylobacter upsaliensis with lower levels of C. jejuni and C. lari (ca. 1%).
The problems is how do you confirm if something is the cause of disease when it is often found in healthy animals? The presence of increased/large numbers of the bacteria in a smears or rectal scrapings may be indicative of it acting as a pathogen. But it may not be definitive. As you have not got anything to compare it too.
It may be that disease is associated more with young or debilitated animals which are often increased at risk. There are also tentative indications that there may be a synergy in symptoms with other pathogenic agents.
What is the morphology of clostridia and what are they capable of producing?
Gram +ve, rod shape, obligate anaerobe
Capable of producing endospores
Name the 4 important species of clostridia?
- C. Botulinum
- C. Difficile
- C. Perfringens
- C. Tetani
What variation is there in clostridia morphology?
perfringens large wide rods
Tetani thin rods (almost drumstick like)
What is this?
Clostridium perfringens
What considerations do we need to be aware of when sampling for clostridia?
- Anaerobic
- Saprophytes found in soil, fresh water and marine (with suitably low redox)
- Also constitute normal part of GI flora.
How do we go about sampling clostridia?
- Sample fresh cadaver material
- as bacteria can grow and spread and confuse results PM
- Placed in anaerobic transport medium
- Prompt culture
Culture is on enriched blood agar (yeast extract, VitK, haemin)
- Media pre-treated or fresh to reduce oxygen.
- Requires anaerobic atmosphere with hydrogen and 5-10% CO2
How can we differentiate clostrdia? (4)
- C. perfingens double haemolysis
- Biochemical identification (commercial kits)
- Toxins can be identified by ELISA.
- Antibody based techniques from lesion samples.
How ca we diagnose Lawsonia? (3)
- Hard to culture as obligate intracellular pathogen.
- Clinical signs and gross pathological findings
- PCR or immuno-fluorescent tests
How can you diagnose Spirochetes & Brachyspira (4)
- Observation in stained fecal smears
- Grow anaerobically
- Confirmed by culture on selective blood agar.
- Differentiation based on haemolysis
What type or bacteria is Mycobacterium avium subspecies paratuberculosis and what does it cause?
Acid fast bacteria
- Causes Johne’s disease in cattle and other ruminants.
- Chronic contagious invariably fatal enteritis
How can we identify Mycobacterium avium subspecies paratuberculosis from live animals?
•Scrapings, pinch biopsies from rectum.
What specimens can we take for diagnosis of Mycobacterium avium subspecies paratuberculosis?
- Post mortem
- Histopathological samples from affected tissue or lymph nodes.
- Microscopy with ZN technique
- Culture is difficult and time consuming up to 16 weeks to grow.
What is going on here?
Ziehl Neelsen (ZN) counterstained with loefflers
Can also counter stain with other stains such as malachite green.
How can you do resistance profiles?
- Disc diffusion
- MIC by E-strips
Define intrinsic resistance
Organism naturally resistant to certain groups of antibiotic
Define acquired resistance
- Heritable – modification of self
- Transferable - acquired good example β-lactamases in Enterobacteriaceae. High frequency in pig farming. Very low in environmental.
Wooden tongue:
A) What type of bacteria casues it?
B) Where is it a commensal?
C) Wat respiration?
D) Oxidase?
E) Urease?
A) Actinobacillus lignieresii - gram -ve rod
B) Commensals of mucous membranes
C) Facultative anaerobe
D) Oxidase +ve Urease +ve
What causes lumpy jaw and how does it happen?
Actinomyces bovis
Invades tissue through breaks in lining of mouth - the damage is due to rough forage or sharp teeth
Fusobacterium necrophorum :
A) Gram?
B) Respiration?
C) Family?
D) Does it form spores?
E) Is it motile?
A) Negative
B) Obligate anaerobe
C) Bacteroidaceae family
D) Non-spore
E) Non-motile
Where is Fusobacterium necrophorum found? How does it infect and how can we treat?
alimentary tract of animals and human beings and respiratory tract of cattle
Infections involve the mucous membranes and underlying tissues of the oral cavity epithelium in calves in pigs less common in goats. To establish infection they usually require injury that breaches an intact epidermal layer. Self limiting.
Initially animals may show signs not drinking.
Often dealt with by farmer.
The pathogenic mechanisms in F. necrophorum infection involve several toxins such as leucocidins, haemolysin and cytoplasmic toxin.
Treatment, course of antibiotics e.g. penicillin’s.
What is this?
Weakly stained rods. Some of the cells have a filamentous form.
Fusobacterium
