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2.2 Microbiology > Denise - Curved Gram Negative Rods (Campylobacter, Helicobacter, Vibrio) > Flashcards

Denise - Curved Gram Negative Rods (Campylobacter, Helicobacter, Vibrio) Flashcards

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1
Q

What are the three curved gram negative rods

A

Campylobacter
Helicobacter
Vibrio

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2
Q

Write about campylobacter species

A

Gram-negative curved, S shaped or spiral rods
Non-spore forming
Oxidase positive
Catalase positive
Motile (uni or bi-polar flagella)
Micrroaerophilic
Some are thermophilic
Do not oxidise or ferment Carbohydrates

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3
Q

What is the main Campylobacter species studied

A

C. jejuni
C. coli
C. fetus
C. cinaedia
C. lari

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4
Q

What are the reservoirs of Campylobacter jejuni

A

Animals
- Poultry up to 98% of carcasses
Undercooked poultry main source
Cross contamination during poultry processing
- unchlorinated water
- milk (raw milk)

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5
Q

What is the incubation time for C. jejuni and C. coli

A

2-7 days

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6
Q

What are the symptoms of C. jejuni and C. coli infection

A

Gastrointestinal infection
- diarrhoea (bloody)
- abdominal pain
- self limiting

Rarely accompanied by systemic disease

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7
Q

Write about C. fetus, C. cinaedi and C. lari infections

A

Systemic infections in the immunocompromised (HIV patients)

Symptoms: fever and headache

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8
Q

What sequelae infections does Campylobacter cause

A

Reactive arthritis (1% of patients after 1-2 weeks)
Bursitis
Endocarditis
Neonatal sepsis
Peripheral polyneuropathy

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9
Q

Write about peripheral polyneuropathy in Campylobacter infection

A

Guillain-Barre syndrome
Paralysis related to nerve demyelination
Molecular mimicry
Cross-reactive antibodies against gangliosides in human peripheral nerves

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10
Q

Write about the isolation of Campylobacter species

A

Difficult
Fastidious growth requirements
Biochemical inertness ( doesnt ferment carbs)
Complex taxonomy

Molecular detection used for screening faeces

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11
Q

What is done on day 1 campylobacter infection

A

Direct Molecular Detection of the SsrA gene

Selective culture

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12
Q

What molecular detection is carried out for the SsrA gene on campylobacter

A

Real time PCR
Enteric BIO
BD Max
Syndromic Testing
BioFire GI Panel

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13
Q

What is done on day 2 investigation of Campylobacter

A

Selective media -> CCDA or chromagar

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14
Q

Writea bout CCDA agar

A

Modified CCDA
Charcoal, cefoperazone, deoxycholate amphericin agar

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15
Q

How does C. jejuni appear on CCDA

A

Grey moist flat spreading colonies

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16
Q

How does C. coli appear on CCDA

A

Creamy grey moist slightly raised

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17
Q

What are the limitations of CCDA

A

Background flora
Media Performance
Slow growth

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18
Q

What are the growth requirements for Campylobacter

A

Strictly microaerophilic
(5-19% O2 with added CO2)
Thermophilic

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19
Q

What are the basic characteristics of Campylobacter

A

Gram negative spiral (gull wing) shaped cells
Small and thin
Coccoid after O2 exposure
Oxidase positive
Catalase positive

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20
Q

What confirmatory tests are carried out for Campylobacter

A

Motile
Hippurate hydrolysis positive
Susceptibility to antimicrobiala

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21
Q

Write about the identification of C. jejuni and C. coli

A

Grow at 42 degrees but not 25 degrees
Susceptible to nalidixic acid
Resistant to cephalothin
H2S positive

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22
Q

What is an important ID of C. jejuni

A

Hydrolyses hippurate

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23
Q

What is an important ID of C. fetus

A

Will grow at 25 degrees, some at 42 degrees
Nalidixic acid resistant
Cephalothin suscpetible

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24
Q

Write about the treatment of Campylobacter

A

Fluid and electrolytes (bloody diarrhoea)
Ciprofloxacin
Eryhromycin

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25
Write about the antimicrobial resistance seen in Campylobacter
Fluoroquinolone and Macrolides treatment Resistance via gene mutations and efflux pump
26
How is Campylobacter prevented
Thorough cooking Pasteutisation
27
Write about Helicobacter species
Campylobacter-like organisms found in the stomachs of patients with type B gastritis Curved spiral organisms Helicobacter pylori (human pathogen no animal reservoir)
28
Write about Helicobacter Pylori (5)
Infectious agent associated with peptic ulcer disease Treatable with antibiotics Triggers MALT malignancies Prevalence 50% globally 80% developing countries
29
Write about the pathogenesis of H. pylori (3)
H. pylori penetrates the mucous layer lining the stomach's epithelium, attracted to the chemotactic substances haemin and urea H. pylori recruits and activates inflammatory cells. They also release urease that cleaves urea, producing NH3 that neutralises stomach acid in its vicinity H. pylori cytotoxin and ammonia produced by its urease cause destruction of mucous-producing cells, exposing underlying connective tissue to stomach acid
30
What are the virulence factors of H. pylori
Flagella Urease Exotoxins Secretory enzymes Lipopolysaccharides Outer proteins Type IV secretion system Effectors
31
What do the H, pylori flagella do?
Bacterial mobility and chemotaxis to colonise under mucosa
32
What do the H, pylori exotoxins do
vacA - vacuolating toxin Causes gastric mucosal injury
33
What do the H, pylori secretory enzymes do
Mucinase, protease and lipase Gastric mucosal injury
34
What do the H, pylori Type IV secretion system do
Pilli-like structure for injection of effectors
35
What do the H, pylori urease do
Neutralises gastric acid Gastric mucosal injuria by ammonia
36
What do the H, pylori lipopolysaccharides do
Adhere to host cells Inflammation
37
What do the H, pylori outer proteins do
Adhere to host cells
38
What do the H, pylori effectors do
cagA Actin remodelling IL-8 induction, host cell growth and apoptosis inhibition
39
How do we detect H. pylori
Invasive techniques to examine stomach Gastric biopsies taken at endoscopy Real time PCR on faeces Serology Urea breath tests Faecal antigen tests
40
Write about the sampling for H. pylori
H, pylori is a fragile organism - dessiccation - contact with oxygen - room temperature Grinding of biopsy specimens Isolation of the organism: fastidious Agar base, blood supplement, antimicrobicals Microaerophilic capnophilic 37degrees for 3-7 days
41
What is important to note about the staining of H. pylori
Young cultures grown in vitro frequently stain gram-positive
42
What are the basic characteristics of H. pylori
Gram negative spiral Oxidase positive Catalase positive
43
What confirmatory tests are done for H. pylori
Urease test - positive Molecular detection for ure cagA targets
44
How is H. pylori treated
Triple therapy with: - amoxicillin - clarithromycin - proton pump inhibitor
45
Write about the vibrio species
Closely related to enterobacterales Motile single motile flagella Natural constituents of freshwater, estuarine and marine environments Seasonal distribution warmer months 2 chromosomes Recombination and horizontal gene transfer O antigens in GN Outer Membrane are useful for ID
46
What are the reservoirs for Vibrio
Faecal contamination of water and food Closely linked to poor sanitation and lack of clean drinking water At risk areas: slums, camps for refugees Disruption of water/sanitation systems Seasonal warming of coastal water increase risk
47
Write about cholera infection
3-5 million cases a year 100,000 deaths a year (50% in children <5) Acute secretory diarrheal illness Rapidly dehydrating Endemic, epidemic, or a pandemic disease
48
Write about the epidemiology of Cholera
Endemic to 50 countries Epidemics in africe, asia, middle east, south america etc Haiti epidemic of 2010 Yemen epidemic of 2017 -> 330,000 cases
49
What are the two main cholera toxins
Cholera toxin (CT) Toxin-coregulated pilus (TCP)
50
Write about the cholera toxin pathogenesis
AB toxin AB5 family - ADP ribosyltransferase Fluid loss via CAMP-mediated activation of anion secretion Inhibition of electoneutral NaCl absorption Massive Cl- secretion leads to severe diarrhea Encoded on filamentous phage CTXO
51
Write about the toxin-coregulated pilus (TCP)
Type IV pilus Mediates adherence and microcolony formation Required for intestinal colonisation Encoded on V, cholerae pathogenicity island (VPI) TCP is the receptor for CTXO
52
What is done on the day 1 investigation of cholera
Direct detection for V. cholera gene - Real time PCR - EntericBIO DX - Syndromic testing - Biofire GI panel
53
What is done on day 2 investigation of cholera
Selective enrichment - alkaline peptone water
54
What is done on day 3 investigation of cholera
Selective culture - TCBS/Chromagar
55
What is done on day 4 investigation of cholera
Biochemical ID Ref lab serotyping Ref lab toxin detection
56
Write about the basic characterisitics of cholera
Curved GNB Oxidase-positive
57
What are the biochemical results of cholera
Non lactose fermenter Sucrose positive
58
How is cholera enriched
Alkaline peptone water
59
How is cholera selectively isolated
Thiosulfate citrate bile salts sucrose agar - sucrose positive MacConkey - NLF
60
How is cholera treated
Fluid and electrolytes Doxycycline Ciprofloxacin
61
How is cholera prevented
Vaccination Public Health Faecal contamination of water supplies
62
What is done on day 3 investigation of campylobacter
Biochemical ID Ref lab

2.2 Microbiology (60 decks)

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