Transcript Campylobacter jejuni

Campylobacter
Campylobacter
Among the most widespread cause of
infection in the world.
Cause both diarrheal and systemic
diseases
Campylobacter jejuni
Typical Organisms
Gram-negative rods
with comma, S, or
“gull-wing” shapes.
Motive, with a single
polar flagellum
No spore & no
capsule
Culture
An atmosphere with reduced O2 (5% O2)
with added CO2 (10% CO2)
At 42 ℃ (for selection)
Several selective media can be used
(eg, Skirrow’s medium)
Two types of colonies:
 watery and spreading
 round and convex
Virulence Factor
Lipopolysaccharides (LPS) with
endotoxic activity
Cytopathic extracellular toxins and
enterotoxins have been found
Pathogenesis
The infection by oral route from food, drink, or
contact with infected animals or animal
products(Milk, meat products ).
Susceptible to gastric acid (about 104
organisums)
Multiply in the small intestine
invade the
epithium
produce inflammation
cause
bloody stools
Occasionally, the bloodstream is invaded
Campylobacter - symptoms
• Incubation: 4-8d
• Acute enteritis: 1w,
stools remain positive for
3w
• Acute colitis
• Acute abdominal pain
• Bacteremia: <1% C.
jejuni
• Septic abortion
• Reactive arthritis
• diarrhea
• malaise
• fever
• abdominal pain
• usually self-limiting
• antibiotics
occassionally
• bacteremia
–small minority
Diagnostic Laboratory
Tests
Specimens: Diarrheal stools
Smears: Gram-stained smears of stool
may show the typical “gull-shaped” rods.
Culture: (have been described above)
Control
The source of infection may be food (eg,
milk, under-cooked fowl) or contract
with infected animals or humans and
their excreta.
Helicobacter pylori
Curved bacilli –
Former name - Campylobacter pylori,
H.
pylori
Helicobacter pylori
Helicobacter pylori is the prototype
organism in this group. It is associated
with antral gastritis, gastric ulcers, and
gastric carcinoma.
Microbiology
Gram negative rod, curved,
Very Motile  corkscrew motion
Microaerophilic, use amino acids and fatty
acids rather than carbohydrates to obtain energy
needs 10% CO2 and 5% O2
Urease production
Catalase production
Oxidase positive
Growth at 370C, not 250C or 420C
Virulence factors
vacA (vacuolationg associated)
cytotoxin, Pathogenicity island: cag,
cytotoxin associated gene A+genes
related to bacterial secretion
Cag+ HP is much more associated
with peptic ulcer disease than Cag(--)
HP.
Pathogenesis
Motility – it moves into the mucus
and produces adhesins on
gastric epithelial cells
(not intestinal epithelial cells)
Urease production, breaks down
the urea to ammonia which buffers
the pH around the bacterium.
Persists, escape defense
mechanisms – SOD, catalase,
Urease. Breack down free radicals
Pathogenesis
H pylori invade the epithelial cell surface
to a certain degree
Toxins and LPS may damage the
mucosal cells
NH3 produced by the urease activity
may also damage the cells
Epidemiology
Epidemiology
Prevalence related to socioeconomic level during
childhood.
Infection occurs in childhood, persists for
decades
Prevalence among adults – 20%-100%
Source – stomach of humans
Mode of transmission? Fecal-oral? Oral-oral?
Vomiting and aerosols ?
Incidence of HP colonization is declining in
developed countries
Epidemiology
Under age 30
<20%
At age 60
40-60%
In developing countries
>80% in
adults
Acute epidemics of gastritis suggest a
common source for H pylori.
Clinical features
Acute acquisition - nausea, vomiting, abdominal pain
last for 1w, later – gastritis.
Persistent colonization - after acquisition,
persist for years. Asymptomatic.
Duodenal ulcer
- more than 90% with DU - carry HP.
- antimicrobial therapy response, eradication of
HP - less recurrences
Gastric ulcer - 50-80% HP
Gastric carcinoma -HP induces gastritis,
gastritis is risk factor for Carcinoma.
Gastric lymphoma - MALToma: mucosa
associated lymphoid tumors, strong
association with HP. Stage 1 is cured by
antibiotics.
Esophageal diseases - HP protects
against: gastroesophageal reflux,
Barrette's esophagus and carcinoma of
esophagus.
Immunity
An IgM antibody response to he
infection is developed
Subsequently, IgG and IgA are
produced
Laboratory diagnosis
Endoscopy and biopsy.
Urease detection
Culture
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!!
Serology
Principles of therapy
Combination chemotherapy
Some drugs are effective in vitro, not in
vivo - due to acidic pH - erythromycin
Resistance - not to bismuth salts or
tetracyclines, 10-30% to metronidazole,
Response - 1 month after cessation of
therapy for breath test or biopsy, 6 month
for serology
Principles of therapy
Triple therapy:
Bismuth+metronidazole+amoxicillin:
eradication 60-90%, tetracyclines, macrolides
- clarithromycin
PPI proton pump inhibitors therapy:
omeprazolone lansoprazole: inhibit HP,
urease, acid
PPI+amoxicillin+clarithromycin or
metronidazole
PPI+ Bismuth+metronidazole+amoxicillinvery effective
PSEUDOMONAS
假单孢菌属
Common Characteristics
Gram-negative
Motile
Aerobic rod
Some produce water-soluble
pigments
Widely in soil, water, plants and
animals
More than 200 (up to now)
Some of the medically important
pseudomonas
rRNA Homology Group
and Subgroup
I. Fluorescent Group
Genus and Species
Pseudomonas
Pseudomonas
Pseudomonas
Nonfluorescent Group Pseudomonas
Pseudomonas
aeruginosa
fluorescens
putida
stutzeri
mendocina
II.
Burkholderia pseudomallei
Burkholderia mallei
Burkholderia cepacia
Ralstonia pickettii
III.
Comamonas species
Acidovorax species
IV.
Brevundimonas species
V.
Stenotrophomonas maltophilia
Pseudomonas aeruginosa
Pseudomonas aeruginosa
Widely distributed in nature
Frequently present in small numbers in the normal
intestinal flora and on the skin
Commonly present in moist environments in
hospitals
It is primarily a nosocomial pathogen
Typical Organisms
Gram-negative rod ---0.6×2 μm
Unipolar flagellum (1~3) --- actively mobile
Occurs as single bacteria,
in pairs, and occasionally
in short chain
Capsule
Pili in strains obtained
from clinical specimens
Culture
Grow readily on many
types of culture media
Smooth and round colonies
Multiple colony types in one culture
Fluorescent greenish color
Sometimes produce a sweet or grapelike or corn taco-like odor
Culture
Obligate aerobic
Grow well at 37~42℃and no growth at 4℃
Produce water-soluble pigments
Pyocyanin; Pyoverdin; Pyorubin; Pyomelanin
Produce hemolysin
Oxidase-positive
Ferment glucose but not other carbohydrates
Virulence Determinants
Virulence Determinants
Adhesins
Invasins
fimbriae (N-methyl-phenylalanine pili)
polysaccharide capsule (glycocalyx)
alginate slime (biofilm)
elastase
alkaline protease
hemolysins (phospholipase and lecithinase)
cytotoxin (leukocidin)
siderophores and siderophore uptake systems
pyocyanin diffusible pigment
Virulence Determinants
Motility/chemotaxis
Toxins
Flagella
Exoenzyme S
Exotoxin A
Lipopolysaccharide
Antiphagocytic surface properties
Capsules, slime layers
LPS
Defense against serum bactericidal reaction
Slime layers,capsules
LPS
Protease enzymes
Virulence Determinants
Defense against immune responses
Capsules, slime layers
Protease enzymes
Genetic attributes
Genetic exchange by transduction and conjugation
Inherent (natural) drug resistance
R factors and drug resistance plasmids
Ecologic criteria
Adaptability to minimal nutritional requirements
Metabolic diversity
Widespread occurrence in a variety of habitats
Inhibition of protein synthesis
in susceptible cells ----Toxin A
The resultant ADP-ribosyl-EF-2 complex is
inactive in protein synthesis.
This intracellular mechanism of action of
toxin A is identical to that of diphtheria toxin
fragment A .
Diverse sites of infection by
P aeruginosa
Disease caused by
Pseudomonas aeruginosa
Endocarditis
Respiratory infections
Bacteremia
Central Nervous System infections
Ear infections including external otitis
Eye infections
Bone and joint infections
Urinary tract infections
Gastrointestinal infections
Skin and soft tissue infections, including
wound infections, pyoderma and dermatitis
Who are at risk?
People with cystic fibrosis
Burn victims
Individuals with cancer
Patients requiring extensive stays in
intensive care units
Diagnosis
Isolation and laboratory identification.
blood agar plates
eosin-methylthionine blue agar.
Gram morphology,
Inability to ferment lactose
Positive oxidase reaction
Fruity odor
Ability to grow at 4 2 ℃
Fluorescence under ultraviolet radiation helps
in early identification of P aeruginosa colonies
and also is useful in suggesting its presence in
wounds.
Control and Treatment
The spread of Pseudomonas is best controlled
by cleaning and disinfecting medical equipment.
In burn patients, topical therapy of the burn with
antimicrobial agents such as silver sulfadiazine,
coupled with surgical debridement, has
markedly reduced sepsis.
Susceptibility testing is essential.
The combination of gentamicin and carbenicillin
can be very effective in patients with acute P
aeruginosa infections.
Review
General characteristics: Gram negative rod,
unipolar flagellum, actively motile; produce
diffusible pigments -- pyocyanin,gluorescin and
pyorubin; aerobic, produce hemolysin.
Pathogenicity: cause suppurative infections in
burn, trauma, etc.
Endotoxin: main pathogenic substance
Exotoxin A
Extracellular enzymes:phospholipase,
proteinase, etc.
Bacteriological diagnosis:
Specimens
Culture and identification
Unusual bacteria
Haemophilus influenzae
Common Characteristics
Small, gram-negative
Pleomorphic
Require enrich media (usually
containing blood for isolation)
No flagellum, no spore
Divided into 17 species according to
different requirement to X and V factor
Haemophilus
Small Gram-negative
coccobacilli, facultative
anaerobes, non motile
often resemble cocci, eg
pneumococci,
most non-encapsulated strains -- virulent forms encapsulated
fastidious (require blood
factors)
X factor = hematin
V factor = NAD
Organisms: H. influenzae: H.
ducreyi --( soft chancre); H.
aegypticus -- (purulent
conjunctivitis)
Characteristics and growth requirements
of some haemophilus species
Species
H influenzae (H aegyptius)
H parainfluenzae
H ducreyi
H haemolyticus
H parahaemolyticus
H aphrophilus
Requires
X
V
+
+
+
+
+
+
+
-
Hemolysis
+
+
-
X=heme; V=nicotinamide-adenine dinucleotide
Haemophilus influenzae
Present in the nasopharynx of approximately
75 percent of healthy children and adults
(non encapsulated strains as the normal flora)
Rarely encountered in the oral cavity
Has not been detected in any other animal
species
6 types(a-f) according to capsular
polysaccharide type in the encapsulated
strains
H. influenzae type b (Hib) encapsulated
strain is the most common cause of
meningitis in children between the ages of 6
Biological Characteristics
----Morphology of organism
In specimens of acute infections:
short (1.5μm) coccoid bacilli
sometimes in pairs or short chain
In culture:
At 6~8 h on rich medium: small coccoid
bacilli
Later: longer rods, lysed bacteria,
pleomorphic
Biological Characteristics
---- Colonies
On brain-heart infusion agar with blood:
Small, round, convex, iridescence
(24h)
On chocolate agar:
Takes 36~48h to develop 1mm
colony
Satellite phenomenon
Not hemolytic
satellite phenomenon
Biological Characteristics
---- Growth
Aerobic or facultative anaerobic
Grow well at 33~37℃
Require X and V factors
Grow better on chocolate agar than on
blood agar
Virulence factor
Endotoxin
Lipooligosaccharide
Neuraminidase
IgA protease
Fimbriae
Polyribosyl ribitol phosphate (PRP)
capsule (the most important)
Disease caused by H. influenzae
Naturally-acquired disease caused by H.
influenzae seems to occur in humans only.
Bacteremia
Acute bacterial meningitis
Epiglottitis (obstructive laryngitis),
Cellulitis
Osteomyelitis
Joint infections
Ear infections (otitis media)
Sinusitis associated with respiratory tract
infections (pneumonia)
Child has swollen face
due to Hib infection,
tissue under the skin
covering the jaw and
cheek is infected,
infection spreading into
her face.
An infant with severe vasculitis
with disseminated intravascular
coagulation (DIC) with gangrene
of the hand secondary to
Haemophilus influenzae type b
septicemia - prior to the
availability of the Hib vaccine
Immunity
Relation of the age incidence of bacterial meningitis caused by
H influenzae to bactericidal antibody titers in the blood
Host resistance to infection
Bactericidal antibody directed against
PRP capsule of H. influenzae type b
Antibody to somatic (cell wall) antigens
Who is at risk?
Young children under 5 years (most
cases occurring in infants between 6-11
months of age)
Day-care attendees
Those in contact with household cases of
Hib disease
Immune deficiencies that lower the body's
resistance to infection
Diagnosis
The history and the physical exam.
Detecting the bacteria in blood, spinal
fluid, or other body fluid
Satellite phenomenon
Treatment
H. influenzae meningitis: ampicillin for strains of the
bacterium that do not make ß-lactamase; a thirdgeneration cephalosporin or chloramphenicol for
strains that do.
Chloramphenicol for penicillin-resistant H. influenzae
Third-generation cephalosporins, such as ceftriaxone
or cefotaxime: effective against H. influenzae and
penetrate the meninges well
Tetracyclines and sulfa drugs: sinusitis or respiratory
infection caused by nontypable H. influenzae.
Amoxicillin plus clavulanic acid (Augmentin): effective
against ß-lactamase producing strains.
Control
Hib conjugate vaccines licensed for use among children
Haemophilus ducreyi
Gram negative pleomorphic rods
Coccobacilli
filamentous
Painful chancres become pustular,
eroded, ulcerated and
there are NO defined borders
LPS
Pili
Outer membrane proteins
Hemolysin
IgA protease
DIAGNOSIS:
Generally made on presentation only.
Soft, very painful chancre.
Gram stain and Laboratory Growth
Growth REQUIRES X (hemin) factor only (H. influenzae needs X and V)
Organisms also grow best in an increased CO2 environment.
Legionella
46 species of Legionella and 68
serogroups.
1976 outbreak of pneumonia occurred
among persons attending a convention
of the American Legion in Philadelphia
费城.
First defined Legionella pneumphila.
Morphology
 Aerobic ,gram-negative, motile, catalase-
positive
 Stain poorly by gram’s method,basic fuchsin
should be used as the counterstain
 Grow on BCYE(buffered charcoal-yeast extract
agar) with -ketoglutarate,at pH 6.9, 35 C,90%
humidity
3 days of incubation,colonies are round or flat
with entire edges.
Color vary from colorless to pink or blue
0.5-1 um wide ,2-50 um long
Cell products
Produce distinctive 14-17 carbon
branched-chain fatty acid.
Produce proteases, phosphatase, lipase,
Dnase,& Rnase
Produce a metalloprotease
Transmission
contaminated air
 infected
water supply
not spread person-person
Pathogenesis
Attach to phagocytic cell surface
1).no antibody : C3 deposite on the bacterial
surface,attached to CR1 or CR3
2).antibody is present : Fc-mediated phagocytosis
• fail to fuse with lysosomal granules and ribosomes,mitochondria
around vacuoles containing L pneumophila, Then cells are
destroyed
Pontiac fever
marked by fever, chills, headache and malaise that lasted 2-5
days
Legionnaire's disease
the more severe form of infection which includes pneumonia
Immunity
Antibodies 4-6 weeks after infection
Cell-mediated response is important
Epidemiology
1)When legionellosis occur?
they are are usually occur in the summer and early fall, but
cases may occur year-round. About 5% to 30% of people who
have Legionnaires' disease die.
2)How is legionellosis spread?
Legionella are typically associated with aerosolized water
(central air conditioning, cooling towers, showers, whirlpool
spars).
Disease is generally waterborne; transmission occurs via
airborne droplets.
3)Where is the Legionella bacterium found?
The organisms exist in many types of water systems in nature;
humans are an accidental host.
Risk Groups
The elderly, cigarette smokers, persons with chronic lung or
immuno-compromising disease, and persons receiving
immunosuppressive drugs
Diagnosis
Clinical: Symptoms include headache, malaise, rapid
fever, nonproductive cough, Chest X-rays show pneumonia
Laboratory: immunofluorescent(IF) ,silver stain.
Legionella antigens in urine samples
Legionella-specific serum antibody
Treatment
Erythromycin
Rifampicin
Pontiac fever requires no specific treatment
Control
Regular maintenance of air conditioning or the inclusion of
biocidal compounds into water cooling towers reduces the
reservoir. Similarly, hyperchlorination of the water supply
eliminates the source.
Bordetella
Bordetella pertussis
Classification – the
genus contains
three medially
important species
B. pertussis
 B. parapertussis
 B. bronchoseptica

Virulence
factors
Pili for attachment
Pertactin, an outer membrane protein also acts as an adhesion
FHA: Filamentous hemagglutinin
PT: Pertussis toxin
Bacterial adenylate cyclase
Dermonecrotic toxin –causing strong vasoconstrictive effects.
Tracheal cytotoxin –the killing and sloughing off of ciliated cells in the
respiratory tract.
Lipooligosaccharide associated with the surface of the bacteria and has
potent endotoxin activity
pertussis toxin
Pertussis is generally a disease of
infants (50% of cases occur in
children less than 1 year old).
Acquired by inhalation of droplets
containing the organism
The organism attaches to the ciliated
cells of the respiratory tract. During
an incubation period of 1-2 weeks,
the organism multiplies and starts to
liberate its toxins.
Next the catarrhal stage occurs This last ~ 2 weeks.
duration
symptoms
bacterial
culture
Next is the paroxysmal stage that lasts ~ 4 weeks. The
patient has rapid, consecutive coughs with a rapid
intake of air between the coughs (has a whooping
sound). The ciliary action of the respiratory tract has
been compromised, mucous has accumulated, and the
patient is trying to cough up the mucous
accumulations. The coughs are strong enough to
break ribs! Other symptoms due to the activity of the
released toxins include
Finally there is a convalescent stage during which
symptoms gradually subside. This can last for months.
B. pertussis rarely spreads to other sites, but a lot of
damage may occur, such as CNS dysfunction which
occurs in ~10 % of the cases and is due to an unknown
cause. Secondary infections such as pneumonia and
otitis media are common.
Incubation
catarrhal
paroxysmal
convalescent
7-10 days
1-2 weeks
2-4 weeks
3-4 weeks or longer
rhinorrhe
a,
malaise,
fever,
sneezing,
anorexia
repetitive
coughwith
whoops,vomiting,
leukocytosis
Diminished
Paroxysmal cough,
Development of
secondary complications
(pneumonia,seizures,enc
ephalopathy)
none
B. Parapertussis & B.
bronchoseptica
B. parapertussis – causes a mild form of
whooping cough
 B. bronchoseptica

Widespread in animals where it causes kennel
cough.
 Occasionally causes respiratory or wound
infections

CONTROL
Sanitary: This very contagious disease
requires quarantine for a period of 4-6
weeks.
Immunological: Pertussis vaccine is a
part of the required "DPT" schedule.
Chemotherapeutic: Antibiotic
prophylaxis (erythromycin) may be used
for contacts. Treatment of disease with
antibiotics does not affect its course
References:
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