Diagnostic microbiologylecture: 7

CAMPYLOBACTER

Abed ElKader Elottol MSc. Microbiology

2010

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GENERAL CHARACTERISTICS OF CAMPYLOBACTER

• Small, delicate, spirally or curved.• Gram-negative bacteria• Oxidase positive• Fastidious• Microaerophilic• Motile by polar flagella

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SPECIES

1 .Camplylobacter fetus subsp. fetus Non pathogenic2 .Campylobacter fetus subsp. intestinalis

3 .Campylobacter fetus subsp. jejuni4 .Campylobacter pylori or Helicobacter pylori (Peptic ulcer)

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Sources of Campylobacters:

GIT and reproductive organs of: • Chicken • Sheeps • Cattles• Dogs• Cats

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Transmission routes

Direct occupationalContact

Farmers,Butchers, Poultry processors

Direct domesticContact

Dogs,CatsChildren to children

Indirect transmission

Untreated waterRaw milk

Undercooked meat

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DISEASES

1. meningitis and meiningoencephalitis in infants: Mortality rate is 50% despite intensive treatment. Specimens include blood, CSF and stool Mostly caused by C. intestinalis.

2. Bacteremia: In children: caused by both C. intestinalis and jejuni. Specimen is blood.

3. Disseminated infections in adults: Usually in debilitated patients with one or more of the following conditions:

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1. Cardiovascular disease.3. Endocrinological disorders4. Chronic alcoholism5. MalignanciesCausative organism: Mostly C. intestinalis= Specimen: Blood, pericardium, pleura, joints and stool.• II. Enteric Infections:• Species of the genus campylobacter, are one of the major

etiologic agents of bacterial enteritis.• Campylobacter enteritis is accompanied by fever, headache,

muscular pain, nausea and pain. • 24 hours following this acute phase, diarrhea develops which

may be bloody, mucoid and watery.8

Isolation of Campylobacter from Stool• 1. Filtration Technique:1. One gram of stool specimen is suspended in 20 ml saline2. Agitate vigorously (on Vortex for 10-15 seconds).3. Centrifuge at 650-800 rpm for 10 minutes.4. Take four to five milliliters into a syringe5. Pass the liquid through two 25 μm filter chamber:=The upper non-sterile chamber is fitted with an 8.0 and 1.2 μm

Millipore membrane filter.= The lower steam-sterilized chamber contains a 0.65 um membrane.6. 2-4 drops of the filtrate are spread onto chocolate agar and incubated.7. Both C. jejuni and intestinalis grow well on this medium and are very

Characteristics.

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Incubation conditions

1. Microaerophilic environment: • 5% O2• 10% CO2• 85% N22. To increase the size of C. jejuni, incubate at 42 oC.

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Selective media

• The introduction of selective media made the isolation of Campylobacter species from a stool sample possible:

• EXAMPLE: Blood Agar + Antibiotic solution.

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Skirrow agar:

• Campylobacter Skirrow Agar is a selective solid medium used for the cultivation and isolation of Campylobacter jejuni from fecal specimens.

• Vancomycin, Polymyxin B, Trimethoprim• Colonies of C. jejuni will appear on Campylobacter Skirrow

agar as small, mucoid, flat or slightly raised, non-hemolytic translucent and gray.

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Butzler solution

• Bacitracin• Cyclohexamide• Colistine B sulfate• Cephazolin sodium• NovobiocinCampy-BAP it contain• Vancomycin• Trimethoprim

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Advantages of filtration technique over the selective media

1. All non-campylobacter organisms are retained by the filters.2. Both C. intestinalis and jejuni will grow on Chocolate agar

unlike the selective media which allows only one of the two.3. You do not need to worry about the decay of antibiotics as in

the selective media.

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SEROLOGICAL TESTS:• Serological tests are not suitable for routine investigation

due to the lack of standardized antigen suspensions and reference sera.

ANTIBIOTIC SENSITIVITY:• Erythromycin is the drug of choice. • Chloramphenicol, aminoglycosides, carbenicillin,

clindamycin and tetracycline are also effective.

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HELICOBACTER PYLORI

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Helicobacter pylori

• Previous name : Campylobacter pylori• First isolated in 1983 from human stomach• Gram-negative bacilli• Curved, spiral or seagull-shaped• Motile with multiple polar flagella

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CULTURAL CHARACTERISTICS

• Grow best at 42-43 oC• Microaerophile (7% oxygen)• Strongly urease positive (different from Campylobacter)• Grow on enriched & selective media Modified Skirrow’s agar

(Blood agar with antibiotics)

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HABITAT• Human gastric mucosa (world-wide distribution)• Approx. 50% of adults >60 years are infectedTRANSMISSION (person to person)• Oral-oral• Fecal-oral• There are clusters of infection in familiesDISEASES BY H. PYLORI• Gastritis• Gastric & peptic ulcer• Gastric cancer• Most individuals tolerate the presence of H. pylori for decades

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CLINICAL FEATURES

• Incubation period : few days• Nausea, flatulence & bad breath• Recurrent epigastric pain & dyspepsia• Epigastric burning sensation• Bleeding from ulcer• No dissemination

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LAB IDENTIFICATION

Specimen : gastric biopsyDirect gram-stained smear of crushed biopsyDirect urease testPlace a piece of biopsy in urea broth- red color change in few min to 2

hrs• Culture : On Skirrow’s medium° Oxidase +ve, Urease +ve, catalase +v• Serodiagnosis

° ELISA to detect IgG (not established to differentiate active vs past

infection)

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H. pylori Stool Antigen (HpSA) testUrea Breath Test• Patient ingests radio-labeled 14C ureaIf H. pylori infection present :• Urease produced by the organism, hydrolyses

urea to NH3 and radio-labeled -HCO3that is exhaled as CO2 which is detected by

spectrometer• Has good sensitivity & specificity.

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• TREATMENT• Triple therapy• • Metronidazole +• • Clarythromycin or amoxycillin +• • Omeprazole

• Vaccine development : under trial

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END OF LECTURE

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