Download Campylobacter

Campylobacter
Campylobacter
Comma shaped ,gram (-) rods,0.2-0.5μm wide ₓ 0.55.0 μm
Motile by a polar flagellum
Most species microaerophilic
25 species and 11 subspecies
Different O antigens, heat-labile capsular and flagellar
antigens are used for epidemiological classification of
clinical isolates
C.jejuni : gastroenteritis
C.coli : gastroenteritis
C.upsalensis: gastroenteritis
C.fetus: systemic infections (bacteremia, septic
thrombophlebitis, arthritis, septic abortion, meningitis)
Campylobacter jejuni
Structure :Thin ,gram (-) rods with comma , S or gull
wings shapes, motile with a single polar flagellum.
Culture: Charcoal or blood (remove toxic oxygen
radicals) with antibiotic added media is required
grows at 37-42°C in a microaerophilic conditions ( 5%7% oxygen) and 5%-10%CO2 on selective Skirrow`s
medium contains vancomycin ,polymyxin B , and
trimethoprim . Colonies are colorless to gray.
Growth characteristics : oxidase (+), catalase (+)
Small size of Campylobacter is used for recovering by
filtration of stool specimen ( 0.45 μm filter)
Do not oxidize or ferment carbohydrates
Antigenic structure : LPS , enterotoxins
Campylobacter (Virulence)
cytotoxic enzymes , enterotoxins, adhesins are
detected
Factors that regulate adhesion, motility and invasion
into intestinal mucosa are poorly defined.
Guillain – Barre syndrome believed to be an
autoimmune disorder of the peripheral nervous
system characterized by development of symmetrical
weakness over several days and recovery requiring
months . caused by antigenic cross-reactivity between
oligosaccharides in bacterial capsule and
glycosphingolipids on surface of peripheral nerve
gangliosides
Reactive arthritis: immune-related late complication ;
painful joint swelling that may last for weeks to a year
Campylobacter jejuni
Pathogenesis :
Is acquired by the oral from food, drink or
contact with infected animals and animal
products.
Is susceptible to acids, 100-500 organisms is
need for infection.
Risk of disease is influenced by infectious
dose.
Patient`s immune status affects the severity of
disease
Patients with hypogammaglobulinemia have
prolonged , severe disease
Campylobacter jejuni(Pathogenesis)
Multiply in the small intestine, invade the
epithelium, produce inflammation.
Mucosal surface appears:
- ulcerated, edematous, bloody
- crypt abscesses in epithelial glands
- infiltration of the lamina propria with
neuthrophils, mononuclear cells, and
eosinophils
Campylobacterjejuni(Pathogenesis)
Gastrointestinal disease produces
histologic damage to the mucosal
surfaces of the jejunum, ileum, colon
Rarely , the bloodstream is invaded
(like enteric fever) (1.5/1000)
Role of cytopathic toxins, enterotoxins
and endotoxic activity have not been
defined
Are killed rapidly by complement and
antibody- mediated serum killing
Campylobacter( epidemiology)
Zoonotic infection ; improperly prepared poultry is
a common source of human infections
Infections acquired by ingestion of contaminated
food (poultry), unpasteurized milk, or
contaminated water
person- to- person (fecal-oral) spread is unusual
Worldwide distribution, with enteric infections most
commonly seen in warm months.
Campylobacter (diseases)
Campylobacter jejuni(diseases)
Acute enteritis with diarrhea, malaise, fever, and
abdominal pain. More than10 bowel movement per day
, bloody stools
Most infections are self-limited but can persist for a
week or more
Colitis, abdominal pain mimicking acute appedicitis,
bacteremia
Chronic enteric infection develop in
immunocompromised patients (AIDS) and difficult to
treat.
Extraintestinal infections are uncommon
Complications:
- C.jejuni ( serotype O:19)and C.upsalensis are
associated with Guillain-Barre syndrome(1/1000)
- reactive arthritis
Campylobacter jejuni(Diagnosis)
Specimens :stool
smears: typical “gull wing “shaped rod in
Gram strain ,Darkfield ,phase contrast
microscopy
Culture :requires use of selective media
( Skirrow ) or incubated in 5-10 CO2 (5-7%
O2 , microaerophilic condition) and 42 °C ;
requires incubation for 2 or more days.
Identification: catalase (+). Oxidase(+)
Campylobacter ( diagnosis )
Campylobacter jejuni(Diagnosis)
Antigen detection: immunoassay
detection of C.jejuni and C.coli
Sensitivity 80%-90% , specificity
>95%
Antibody detection: serologic testing
for IgM and IgG are useful for
epidemiological survays
Campylobacter
( treatment, prevention ,and control)
Treatment : for gastroenteritis , infection is selflimited and is managed by fluid and electrolyte
replacement
Serve gastroenteritis and septicemia are treated
with erythromycin, azithromycin (drugs of choice) ,
tetracycline, clindamycin, amoxiclave, imipenem, or
fluoroquinolones.
More strains are resistant to penicillin,
cephalosporins and sulfanamide
Prevention: Gastroenteritis is prevented by proper
preparation of food and consumption of pasteurized
milk; preventing contamination of water supplies
also controls infection.
Campylobacter fetus
C.fetus is associated with septicemia and is
disseminated to multiple organs and causes diarrhea
(uncommon disease)
Spread from the gastrointestinal tract to the blood and
distal foci.
Spread is common in debilitated and
immunocompromised patients (liver disease, diabetes
mellitus, chronic alcoholism, malignancies)
S protein (heat-stable S layer) in C.fetus inhibits C3b
binding and subsequent complement and antibody mediated phagocytosis and killing (resistant to serum
killing)
Campylobacter fetus
Diseases:
- intravascular infections
(septicemia, endocarditis, septic
thrombophlebitis)
- extraintestinal infections
(meningoencephalitis, abscesses)
Diagnosis: like C. jejuni, but cannot
grow at 42 C
C.upsalensis
Catalase (-) or weakly (+).
Growths at 42C
Highly susceptible to drugs in selective media
(skirrow )
Filter method is suitable for isolation
Domestic pets and cats are reservoir
Opportunistic agent of infections in children
Present as acute enteritis with diarrhea , fever and
abdominal pain
Isolates from stool, blood , fetoplasental material of
human
Is associated with Guillain-Barre syndrome
Arcobacter
Arcobacter
The genus Arcobacter which is related to Campylobacter
was introduced in 1991.
Are aerotolerant
Optimal growth temperature is at 30oC.
Members of this genus inhabit very diverse environments
Distinguishing from Campylobacter:
- Hydrolysis of indoxyl acetate
- growth at 15-36◦ C ,but not at 42◦ C
- Inability to hydrolyze hippurate
•
separated to 5 major groups:
A.cryaerophilus (2 subgroups)
A.nitrofigilis
A.butzleri
A.skirrowii
A. halophilus
Arcobacter
A.cryaerophilus: grows well under aerobic
conditions. May require microaerophilic conditions
for initial isolation
Optimal growth at 30◦ C
Resemble C.fetus but is Indoxyl acetate (+)
Sensitive to nalidixic acid, resistant to cephalothin
Growth in CIN agar is better than Skirrow
A. cryaerophilus has been found both in
association with diseased as well as healthy
humans and animals caused that these bacteria
were considered to play a role as food borne or
waterborne agents
Arcobacter
A.nitrofigilis:
a nitrogen fixing bacterium
a cryophilic species
Grows optimally at 25◦ C
Urea (+)
Non pathogenic for human
A. skirrowii:
isolates from fluids of bulls, aborted fetuses and
diarrheal feces from cows , pigs and sheep.
Arcobacter
A.butzleri: aerotolerant both at 30◦ C
and 36◦C ( separatation from A.
cryaerophilus )
Grows on MacConkey and glycine
and nitrate containing media and in
1.5% and 3.5% NaCl
Isolated from stools of patients with
diarrheal illness.
Rarely isolates from abdominal
contents , peritoneal fluid and blood
Helicobacter
Helicobacter
First isolated by Marshal and Warren in1983
Spiral , G(-) rods resembling campylobacter
(0.5-1.0μm wide*2-4 μm long) , coccoid form
in older cultures
Motile (polar flagella)
catalase and oxidase (+)
- 30 species are characterized according to:
sequence analysis of their 16S rRNA genes
cellular fatty acid , (different from
Campylobacter with high % of O:14 and low
O:16 and presence of O:18-OH-3)
presence of polar flagella
Helicobacter ( diseases)
H.pylori : (gastric)
Gastritis , peptic ulcer, gastric adenocarcinoma,
gastric mucosa-associated lymphoid tissue (MALT)
B-cell lymphomas
H.cinaedi: enterohepatic (isolated from homosexual
men with HIV)
Gastroenteritis, septicemia, proctocolitis, cellulitis
H.fennelliae : enterohepatic(isolated from
homosexual men with HIV)
Gastroenteritis, septicemia, proctocolitis
Helicobacter species flexispira taxon 8:
bactermia with cellulitis in immunocompromised
patients
H.canadensis : Gastroenteritis
H.canis:Gastroenteritis
H.pullorum:Gastroenteritis
Helicobacter pylori
Morphology : Curved, gram- negative rods ,
motile by multiple flagella at one pole
Lipid A has low endotoxin activity compared
with other (-) bacteria
O side chain is antigenically similar to Lewis
blood group antigens, which may protect the
bacteria from immune clearance
H.pylori
Culture: require complex medium
supplemented with 5% defibrinated horse
or sheep blood, serum, charcoal, starch,
egg yolk( Brucella agar ,BHI,or TSB
mediums with supplements and
antibiotics ) .
Microaerophilic conditions( 10% CO2, 5%
O2 and 85% N2 or 10%CO2 with air ).
Grows in 3-6 days at 37°C in a
microaerophilic environment in Skirrow`s
medium with vancomycin, polymyxin B
and trimethoprim ; and in chocolate
medium
H.pylori
Growth characteristics : oxidase- positive ,
catalase-positive, do not ferment or
oxidase carbohydrates, metabolize amino
acids by fermentative pathways
-Urease production at very high levels is
typical of gastric helicobacters, and
uncommon in intestinal helicobacters
- Flagella and urease are important for
survival in gastric acids and rapid
movement through the viscous mucus
layer towards a natural pH environment
H.pylori ( Virulence factors)
H.pylori (pathogenesis)
Virulence factors:
A-Initial colonization of H.pylori facilitate by:
1- blockage of acid production by acid inhibitory
protein
2- Urease activity ;
- neutralization of gastric acids by production of
the ammonia
- stimulate monocytes and neuthrophils
chemotaxis
- stimulate production of inflammatory cytokines
- stimulate production of high amount of gastrin
and acid
H.pylori (pathogenesis)
B- H.pylori can pass through the gastric mucus by
actively motility of flagella
C- adhere to the gastric epithelial cells by multiple
surface-adhesion proteins
- haemagglutinins ; binding to N-acetyl-noraminillactose
- sialic acid- binding adhesin
- pili; adhere to phosphatidyl-ethanol amin and
laminin
- Lewis blood group adhesin; may protect the
bacteria from immune clearance
 Surface proteins can also bind host proteins and
help the bacteria evade immune detection.
H.pylori (pathogenesis)
D- Localized tissue damage is mediated by:
1- Urease byproducts
2-Mucinase; disrupts gastric mucus
3-Phospholipases; C,A1,A2 ; disrupts gastric
mucus
4-Vacuolating cytotoxin A (VacA); after
endocytosis by epithelial cells, damage the
cells by producing vacuoles
- 60% of H.pylori strains produces Vac A
but toxin production is not seen in strains of
Patient with long time non-ulcerative gastritis
H.pylori (pathogenesis)
E- Cag A protein ; interferes with the normal
cytoskeletal structure of the epithelial cells
- an important virulence factor of H.pylori is the
Cytotoxin-associated gene (cagA) that resides on
a pathogenicity island containing approximately 30
genes.
- These genes encode a structural (type IV
secretion system) that acts like a syringe to inject
the Cag A protein into the host epithelial cell
The cag PAI (phosphoribosylanthranilate
isomerase) genes also induce IL-8 production,
which attracts neutrophils.
Release of proteases and reactive oxygen
molecules by the neuthrophils is believed to
contribute to gastritis and gastric ulcers
H.pylori (pathogenesis)
F- Superoxide dismutase; prevent
phagocyting killing by neutralizing
oxygen metabolites
Catalase; prevent phagocyting killing
by neutralizing oxygen peroxides
Heat- shock proteins; enhances
expression of urease
H.pylori (pathogenesis)
Long life colonization in the antrum of
stomach of untreated humans
Grows at pH = 6-7
Gastric mucus is impermeable to acid and
has a buffering capacity.
On the lumen side of the mucus pH is low
(1-2) ;on the epithelial side pH is about 7.4
H.pylori produces a protease
urease activity produces ammonia
TNF-α, IL-6 and IL-8 , urease activity and
cytokines are caused Chronic inflammation
of stomach
H.pylori (pathogenesis)
H.pylori infection (weeks to months)
chronic superficial gastritis ( years to
decades )
- peptic ulcer disease;
- chronic superficial gastritis;
- chronic atrophic gastritis
gastric
adenocarcinoma
H.pylori ( epidemiology)
Infections are common, particularly in people in a low
socioeconomic class or in developing nations (70%-90%)
Humans are the primary reservoir; Incidence of carriage in
developing nations (70%-90%) most before age 10 years.
Person-to-person spread is important (typically fecal-oral)
is worldwide with no seasonal incidence of disease
70%-100% of patients with gastritis, gastric ulcer, duodenal
ulcers are infected with H.pylori
Colonization with H.pylori appears to offer protection from
gastroesophagal reflux disease and adenocarcinoma of
the lower esophagus and gastric cardia
Diseases
Gastritis ; infiltration of neutrophils and
mononuclear cells in to gastric mucosa.
Acute phase: feeling of fullness; nausea;
vomiting; hypochlorhydria ( decreased
acid production );
Chronic phase: disease confined to the
gastric antrum in individuals with normal
acid secretion, or involve the entire
stomach (pangastritis) if acid secretion is
suppressed.
Diseases
Peptic ulcer (10-15%) in chronic gastritis.
Developing to gastric ulcer (isolate 85%) or
duodenal ulcer(isolate 95%)
Gastric cancer; replacement of normal
gastric mucosa with fibrosis and
proliferation of the epithelium in chronic
gastritis. (high risk for cancer is associated
with cagA positive strains and high levels
of IL-1 production)
MALT lymphoma; monoclonal population of
B cells
H.pylori(Diagnosis)
Microscopy : Histological examination of
biopsy specimen is sensitive and specific;
hematoxylin-eosin stain, Gram stain WarthinStarry silver stain( 100% sensitivity and
specificity)
Urease test: relatively sensitive and highly
specific; urea breath test is a noninvasive test
(detection in 1-2 hours with sen. 75-95%and
spe. 100%)
Noninvasive urease testing of human breath:
C13 or C14 labeled urea solution ( excellent
spe. and sen.)
H.pylori(Diagnosis)
H.pylori antigen test : polyclonal and
monoclonal immunoassays for
H.pylori antigens; performs with stool
specimens; sensitive and specific
95%;
Serology: useful for demonstrating
exposure to H.pylori .IgM disappears
rapidly. IgA and IgG persist for
months to years
H.pylori(Diagnosis)
Culture : requires incubation in
microaerophilic condition ; chocolate agar
(nonspecific medium) and modified
Skirrow medium (specific medium) are
required ; growth is slow (up to 2 weeks) ;
relatively insensitive unless multiple
biopsies are cultured
Identification; microscopic morphology,
oxidase , catalase, urease
Nucleic-Acid based amplification tests:
PCR based tests are restricted to
research labs and not in clinical use
.
H.pylori ( treatment)
Treatment : multiple regimens have been evaluated for
treatment of H.pylori infections.
Combined therapy with tetracycline, metronidazole,
bismuth, and omperazole for 2 weeks has had high
success rate
Omperasole + a macrolide (clarithromycin ) a betalactam(amoxicillin) for 7-10 days .
resistance to clarithromycin and metronidasole is
important.( susceptibility testing is recommended)
Prophylactic treatment of colonized individuals has not
been useful and potentially has adverse effects, such
as predisposing patients to adenocarcinomas of the
lower esophagus
prevention and control
Human vaccines are not currently
available
Use of H.pylori antigens in
experimental vaccines that stimulate
TH1 cells leads to enhanced
inflammation
Use of antigens in combination with
mucosal adjuvants that induce aTH2
cell response is protective in an
animal model
Other Helicobacters ( diseases)
H.cinaedi: enterohepatic (isolated from
homosexual men with HIV)
Gastroenteritis, septicemia, proctocolitis,
cellulitis
H.fennelliae : enterohepatic (isolated from
homosexual men with HIV)
Gastroenteritis, septicemia, proctocolitis
Helicobacter species flexispira taxon 8:
bactermia with cellulitis in immunocompromised
patients
H.canadensis : Gastroenteritis
H.canis: Gastroenteritis
H.pullorum: Gastroenteritis