Campylobacter 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% O

2) 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

PathogenesisThe 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 stoolsOccasionally, the bloodstream is invaded

• diarrheadiarrhea• malaise malaise • feverfever• abdominal painabdominal pain• usually self-limiting • antibiotics occassionally• bacteremia

–small minoritysmall minority

CampylobacterCampylobacter - - symptomssymptoms

• Incubation: 4-8d• Acute enteritis: 1w,

stools remain positive for 3 w

• Acute colitis• Acute abdominal pain• Bacteremia: <1% C.

jejuni• Septic abortion• Reactive arthritis

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.

•Curved bacilli –•Former name - Campylobacter pylori,

H. pylori

Helicobacter 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 energyneeds 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

EpidemiologyPrevalence 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% HPGastric 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 13C-labeled 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 - clarithromycinPPI proton pump inhibitors therapy: omeprazolone lansoprazole: inhibit HP, urease, acidPPI+amoxicillin+clarithromycin or metronidazolePPI+ Bismuth+metronidazole+amoxicillin-very effective

PSEUDOMONAS

假单孢菌属

Common Characteristics

Gram-negativeMotileAerobic rodSome produce water-soluble pigmentsWidely in soil, water, plants and animalsMore than 200 (up to now)

Some of the medically important pseudomonas

rRNA Homology Group and Subgroup Genus and Species

I. Fluorescent Group

Nonfluorescent Group

Pseudomonas aeruginosaPseudomonas aeruginosaPseudomonas fluorescensPseudomonas putidaPseudomonas stutzeriPseudomonas mendocina

II. Burkholderia pseudomalleiBurkholderia malleiBurkholderia cepaciaRalstonia pickettii

III. Comamonas speciesAcidovorax species

IV. Brevundimonas speciesV. Stenotrophomonas maltophilia

Pseudomonas aeruginosaPseudomonas aeruginosa

Pseudomonas aeruginosaPseudomonas 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 μmUnipolar flagellum (1~3) ---- actively mobile Occurs as single bacteria, in pairs, and occasionally in short chainCapsule 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 grape-like 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 fimbriae (N-methyl-phenylalanine pili) polysaccharide capsule (glycocalyx) alginate slime (biofilm)

Invasins elastase

alkaline protease

hemolysins (phospholipase and lecithinase)

cytotoxin (leukocidin)

siderophores and siderophore uptake systems

pyocyanin diffusible pigment

Virulence Determinants

Motility/chemotaxis Flagella

Toxins 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

EndocarditisRespiratory infectionsBacteremiaCentral Nervous System infectionsEar infections including external otitisEye infectionsBone and joint infectionsUrinary tract infectionsGastrointestinal infectionsSkin 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

DiagnosisIsolation and laboratory identification.

blood agar plates eosin-methylthionine blue agar.

Gram morphology, Inability to ferment lactosePositive oxidase reactionFruity odorAbility 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

HaemophilusSmall 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 = hematinV factor = NAD Organisms: H. influenzae: H. ducreyi --( soft chancre); H. aegypticus -- (purulent conjunctivitis)

Characteristics and growth requirements of some haemophilus species

X=heme; V=nicotinamide-adenine dinucleotide

SpeciesRequires

Hemolysis X V

H influenzae (H aegyptius)

H parainfluenzae

H ducreyi

H haemolyticus

H parahaemolyticus

H aphrophilus

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Haemophilus influenzaePresent 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 strainsH. influenzae type b (Hib) encapsulated strain is the most common cause of meningitis in children between the ages of 6 months and 2 years.

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 ba

cilli

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 phenomenonNot 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)

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

Child has swollen face due to Hib infection, tissue under the skin covering the jaw and cheek is infected, infection spr

eading into her face.

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 third-generation 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

LPS

HemolysinIgA protease

PiliOuter membrane proteins

Gram stain and Laboratory GrowthGrowth REQUIRES X (hemin) factor only (H. influenzae needs X and V)Organisms also grow best in an increased CO2 environment.

DIAGNOSIS: Generally made on presentation only.

Soft, very painful chancre.

Gram negative pleomorphic rodsCoccobacilli filamentous

Haemophilus ducreyi

Painful chancres become pustular, eroded, ulcerated andthere are NO defined borders

Legionella46 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-positiv

e Stain poorly by gram’s method,basic fuchsin s

hould be used as the counterstain Grow on BCYE(buffered charcoal-yeast extract

agar) with -ketoglutarate,at pH 6.9, 35 C,90% humidity3 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 productsProduce 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

PathogenesisAttach 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 aro

und vacuoles containing L pneumophila, Then cells are destroyedPontiac 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

ImmunityAntibodies 4-6 weeks after infectionCell-mediated response is important

Epidemiology1)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

DiagnosisClinical: 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

ErythromycinRifampicinPontiac fever requires no specific treatment

Treatment

ControlRegular 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

Classification – the genus contains three medially important speciesB. pertussisB. parapertussisB. bronchoseptica

Bordetella pertussis

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

  Incubation catarrhal paroxysmal convalescent

duration 7-10 days 1-2 weeks 2-4 weeks 3-4 weeks or longer

symptoms none

rhinorrhea,malaise,fever,sneezing,anorexia

repetitive coughwith whoops,vomiting,leukocytosis

DiminishedParoxysmal cough,Development of secondary complications(pneumonia,seizures,encephalopathy)

bacterial culture

     

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 organismThe 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.

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 includeFinally 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.

B. Parapertussis & B. bronchoseptica

B. parapertussis – causes a mild form of whooping cough

B. bronchoseptica Widespread in animals where it causes kennel c

ough.Occasionally causes respiratory or wound infecti

ons

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