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Campylobacter


Members of the genus Campylobacter are curved, spiral, or S-shaped organisms that microscopically resemble vibrios.
A single,polar flagellum provides the organism with its characteristic darting motility.
Somatic, flagellar, and capsular antigens all contribute to the numerous serotypes
Most Campylobacter are microaerophilic.
Do not ferment carbohydrates.
General Characteristics Campylobacter


Small, thin (0.2 - 0.5 µm X 0.5 - 5.0 µm), helical (spiral or curved) cells with typical gram-negative cell wall; “Gull-winged” appearanceTendency to form coccoid & elongated forms on prolonged culture or when exposed to O2Distinctive rapid darting motility Long sheathed polar flagellum at one (polar) ends of the cell Motility slows quickly in wet mount preparation Microaerophilic & capnophilic 5%O2,10%CO2,85%N2Thermophilic (42-43°C) (except Campylobacter fetus) Campylobacter jejuni grows better at 42°C than 37°C. Morphology & Physiology of Campylobacter

Zoonotic infections in many animals particularly avian (bird) reservoirs

Humans acquire via ingestion of contaminated food (particularly poultry), unpasteurized milk, or improperly treated water
Epidemiology of Campylobacteriosis

Only 4 species are common human pathogens

1- Campylobacter jejuni is a leading cause of bacterial gastroenteritis

2- Campylobacter coli is a more common cause of bacterial gastroenteritis in developing countries.

3- Campylobacter upsaliensis is most likely an important cause of gastroenteritis in humans.

4- Campylobacter fetus is most commonly responsible for causing systemic infections
Pathogenesis and clinical significance


Campylobacter may cause both intestinal and extraintestinal disease.Food infections (like Campylobacter) have longer incubation periods and require colonization by the bacterium.Food poisonings have shorter incubation periods and only require ingestion of the toxin.Campylobacter jejuni typically causes an acute enteritis.Incubation period (1- 7) day,Symptoms may be both systemic (fever, headache, myalgia) and intestinal (abdominal cramping and diarrhea, which may or may not be bloody).Campylobacter jejuni is a cause of both traveler’s diarrhea and pseudoappendicitis,Bacteremia (often transient) may occur, most often in infants and older adults. Pathogenesis and clinical significance

Pathogenesis and clinical significance

Cellular components:EndotoxinFlagellum: MotilityAdhesins: Mediate attachment to mucosaInvasins GBS is associated with C. jejuni serogroup O19 S-layer protein “microcapsule” in C. fetus: Extracellular components: EnterotoxinsCytopathic toxins Important virulence factors:

Low incidence potential sequels

Reactive, self-limited, autoimmune disease
Campylobacter jejuni most frequent antecedent pathogen
Immune response to specific O-antigens cross-reacts with ganglioside surface components of peripheral nerves (molecular or antigenic mimicry)
Acute inflammatory demyelinating neuropathy (85% of cases) from cross reaction with Schwann-cells or myelin
Acute axonal forms of GBS (15% of cases) from molecular mimicry of axonal membrane
Guillain-Barre Syndrome (GBS)


Specimen Collection and Processing: Feces refrigerated & examined within few hours Rectal swabs in semisolid transport mediumBlood drawn for C. fetus Care to avoid oxygen exposureSelective isolation by filtration of stool specimenEnrichment broth & selective media.Filtration: pass through 0.45 μm filtersMicroscopy:Gull-wing appearance in gram stainDarting motility in fresh stool (rarely done in clinical lab.)Fecal leukocytes are commonly presentIdentification: Growth at 42-43oCHippurate hydrolysis (C. jejuni is positive)Susceptibility to nalidixic acid & cephalothin Laboratory Identification


Microscopy:Is insensitive,Observation of thin, ‘’S shaped organisms’’ in a stool specimen is presumptiveCulture:Requires use of special media (vancomycin, polymyxin B, trimethoprim).Must contain blood or charcoal to remove toxic oxygen radicals,Microaerophilic atmosphere 5-7% oxygen, 5-10 % carbon dioxide and balanced nitrogen level.Positive oxidase and catalase Laboratory Identification

Commercial antigen tests

Antibody detection (IgM and IgG) useful for epidemiological surveys.
Laboratory Identification

Gastroenteritis:

Self-limiting; Replace fluids and electrolytes,

Antibiotic treatment can shorten the excretion period,

Erythromycin is drug of choice for severe or complicated enteritis & bacteremia; Fluroquinolones are highly active (e.g., ciprofloxacin was becoming drug of choice) but fluoroquinolone resistance has developed,

Azithromycin was effective in recent human clinical trials,

Control should be directed at domestic animal reservoirs and interrupting transmission to humans.
Treatment, Prevention & Control




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