Transcript C. jejuni

Campylobacter
Spirally small, curved, G-ve, Motile,
NS, NC bacteria.
They are comma, S, or “gull-wing”
shaped spiral rods.
Motile by single polar unsheathed
flagellum at one or both ends.
Have long been known to cause
Diarrhea in animals but their role in
human diarrhea was only established
in 1970.
Reason:
Gram
staining
shows
pleomorphic G-ve bacilli with
short curved and spiral forms
of bacteria.Typical S shaped.
Coloured scanning electron micrograph (SEM) of a Campylobacter
jejuni bacterium. This motile, Gram-negative bacterium possesses long
flagella, at either end, which enable it to move
Campylobacter is the second most common cause of bacterial
foodborne illness in the United States after Salmonella
16 Species
Medically important are
C.jejuni, C.coli, C.upsaliensis: Causing human diarrhea.
C.fetus
: Cause extraintestinal infection.
C.sputorum, C.rectus:
Periodontal disease.
Culture Characteristics
Campylobacter are
microaerophilic
thermophilic* (growing well at 420C)
Capnophilic(require 10% CO2 )
Survive in Cary Blair media.
Selective Media:
1. Modified Skirrow Media contining blood agar base, &
antibiotics (Vancomycin, Trimethoprim, and Polymyxin B).
2. Campy-Brucella agar with antibiotics
Rectal swab or stool swab or 1 or 2 drop of liquid stool
specimen are inoculated directly on the surface of the agar
medium.
Incubation: 420 C for 48 to 72 hours.
Culture characteristics
Colonies are flat grey, irregular
shaped and moist/ glistening
entire edges.
Biochemical reactions
Epidemiology
Campylobacter infection: Zoonotic with variety of animal serving as
reservoir Chickens, domestic animals (Cattle and Swine) and birds.
Source of infection is food of animal origin, especially raw milk.
It is part of the normal intestinal flora of domestic animals and birds
and is shed in their feces.
Contaminated poultry are responsible for more than half of the
Campylobacter infection.
Human acquire infection with C.jejuni and C.coli after consumption of
contaminated food, milk or water.
Once a person is infected, the organism can be transmitted from
person to person by faecal-oral route.
Incidence rate high among children less than 2 year old and young
adults(20 to 40 years old).
Pathogenesis & Immunity
 Infectious dose and host immunity determine whether
gastroenteric disease develops
• Some people infected with as few as 500 organisms while
others need >106 CFU
 Pathogenesis not fully characterized
• No good animal model
• Damage (ulcerated, edematous and bloody) to the mucosal
surfaces of the jejunum, ileum, colon
• Inflammatory process consistent with invasion of the
organisms into the intestinal tissue; M-cell (Peyer’s patches)
uptake and presentation of antigen to underlying lymphatic
system
 Non-motile & adhesin-lacking strains are avirulent
Pathogenicity
Occurs with in 2-4 days(range of incubation period, 1-7 days) of
ingestion of contaminated food, milk or water.
Cause acute gastroenteritis, last for days to several weeks, usually
self limiting.
Infection first jejunum and ileum and later spread distally to affect
terminal ileum, colon and rectum
C.jejuni is invasive, multiply in small intestine, penetrate gut
epithelium and disrupt fluid absorption.
Virulence factor:
Produce enterotoxin
cytotoxin
Adhesions
Intracellular survival
Ability to penetrate cells
Clinical feature
Fever, headache, myalgia and intestinal– abdominal cramping
and watery diarrhoea with or without blood.
Cause both traveller’s diarrhoea and pseudo appendicitis.
Complication include Guillain Barre syndrome(GBS), septic
abortion and reactive arthritis.
GBS associated with specific C.jejuni serotype O:19.
GBS(Guillain-Barre Syndrome)
 C.jejuni most recognized antecedent cause of GBS, an
acute paralytic disease of the peripheral nervous system.
 20-40% of GBS patients are infected with C.jejuni which
may appear 1-2 weeks after the onset of acute
campylobacter illness.
 It is believed that antigenic cross reactivity between surface
lipopolysaccharides of some strains of campylobacter and
peripheral nerve gangliosides. Thus antibodies directed
against specific strains of Campylobacter can damage
neural tissue in peripheral nervous system.
Laboratory Identification
Specimen Collection and Processing:
 Feces refrigerated & examined within few hours
 Rectal swabs in semisolid transport medium
 Blood drawn for C. fetus
Microscopy:
 Gull-wing appearance in Gram stain
 Darting motility in fresh stool
 Fecal leukocytes are commonly present
Culture
Feces/ rectal swab plated on selective media(Butzler’s selective
medium, Skirrow Campylobacter selective medium, Campy BAP.
Growth at 37o, or 42-43oC.
Colonies typically flat, effuse & tendency to spread on moist
agar. Nonhaemolytic, grey or colorless, moist and flat.
Identification:
Growth at 25o, 37o, or 42-43oC
Hippurate hydrolysis (C. jejuni is positive).
370C
Benzoic acid
+Glycine
2hours
1% Sodium Hippurate+ Suspected isolate colonies
Indicator Ninhydrin is added to detect glycine by turning
inoculated broth deep purple colour.
Serology & Molecular test
CFT & ELISA: Detect recent infection with C.jejuni or C.coli.
PCR amplification of the 16S rRNA gene and sequencing .
Treatment
Gastroenteritis, Infection is self-limited and is managed by
fluid and electrolyte replacement.
Severe gastroenteritis treated with erythromycin and
Ciprofloxacin.
Prevention
Potentially contaminated food, such as poultry, should be
throughly cooked, and milk and milk prodcuts should be
pasteurised.
Helicobacter
First observed in 1983 as
Campylobacter-like
organisms
(formerly Campylobacter pyloridis)
in the human stomachs of patients
peptic ulcer disease(PUD) and
gastric cancer.
Helicobacter pylori is the prototype
organism in this group. It is
associated with antral gastritis,
duodenal ulcer disease, peptic
(gastric )ulcers, and gastric
carcinoma.
H.pylori
Gram negative spirally curved bacilli, NS. Spheroid or
coccoid in old culture.
Very Motile  corkscrew motion with a unipolar tuft of
lophotrichous flagella(Other Helicobacter posses multiple
bipolar sheathed flagella).
Culture: Microaerophilic, 5-10% CO2 & high humidity.
Growth at 370C, not 250C or 420C. Can grow in Skirrow
Campylobacter selective medium.
Produces circular, convex and translucent colonies after 3-7
days.
Biochemical : Urease production(Rapid diagnostic).
Catalase, Oxidase production
Does not metabolize carbohydrates or reduce nitrates.
Colonises the gastric mucosa of almost 50% of the
adult population.
Adapted to human gastric mucosa.
Though contraversial but claims, human acquired
infection as zoonoses from the stomach of other
mammals (cat, dog, mice rats etc) each with its
own helicobacter species.
Person to person transmission by oral-oral and
faecal-oral routes.
Important Human Pathogens:
 Helicobacter pylori , H. cinaedi , H. fenneliae
Virulence factors
• H.pylori produce cytotoxin which cause vacuolation of gastric
mucosa.
• Cag , pathogenicity gene island, a group of genes consist of cag
encoding for cag A protein, and vac(vacuolating cytotoxin gene)
along with over 40 genes.
• Cag A is injected by H.pylori into human gastric epithelial cell and
affect the host cell protein expression inducing cytokine release,
cytoskeletal changes and proliferation to enable H.pylori to
successfully colonise gastric epithelium.
• Urease released by H.pylori producing ammonia ions that neutralise
stomach acid in the vicinity of the organism, thus favoring bacterial
multiplication.
• Bacterial antigen cross react with antran gastric antigen stimulating
an autoimmune response.
• Protease produced by the organism degrade gastric mucosa.
Pathogenesis
H.Pylori colonizes surface of gastric mucosa, especially
antrum(Any part may be colonized).Bacteria present in
large numbers in mucus overlying mucosa(pH=7.0).
Exact
pathogenic
mechanism not known.
Bacterial
protease,
toxins or ammonia or
autoimmune responses
may all contribute.
Where
numerous,
underlying mucosa shows
a
superficial
gastritis
known as type B gastritis.
H.Pylori is associated with antral gastritis,
duodenal(peptic) ulcer disease, gastric ulcers.
Can also
cause gastric malignancies, namely
‘Adenocarcinoma’ and gastric B cell lymphoma(
mucosa
associated
lymphoid
tissue(MALT)
lymphomas).
Laboratory diagnosis
Endoscopy and biopsy
Rapid urease test: A biopsy sample is placed into a urea broth and
an indicator such as phenol red. The urease produced by H.
pylori hydrolyzes urea to ammonia, which raises the pH of the
medium, and changes the color of the specimen from yellow
(NEGATIVE) to red (POSITIVE).
Microscopy: Gram / Giemsa / Warthin-Starry silver stain
H.Pylori in gastric mucosal impression
smear(SilverStaining)
Culture:
Histology more sensitive than culture.
Usually not done.
Only done when sensitivity tests or typing is required.
Tissue biopsy material is collected in Stuart transport media and
cultured in selective media.
Antigen detection
Faecal antigen detection by ELISA(Commercial-Meridian Diagnostic,
USA).
PCR.
Urea breath test - samples of breath air are collected by having the
patient blow into a tube before and 30 min after ingestion of 13Clabeled urea, rapid, noninvasive, for assessing response 4-8w post
therapy, expensive but non invasive!!
Treatment
• PPI proton pump inhibitors therapy
omeprazole / lansoprazole +amoxicillin +
clarithromycin or metronidazole + Bismuth
subsalicylate
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