Campylobacter

Classification

General Characteristics

Basic features

General characteristics of Campylobacter species include:

• Gram-negative
• Ribbon or S-shaped bacilli Bacilli Shigella
• Polar flagella Flagella A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called flagellin. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as cilia but are longer in proportion to the cell bearing them and present in much smaller numbers. Helicobacter
• Microaerophilic Microaerophilic Helicobacter or partially anaerobic
• Thermophilic:
  • Preferred growth at 37–42°C (98.6–107.6°F)
  • Key factor used to distinguish from Vibrio cholerae Vibrio cholerae The etiologic agent of cholera. Vibrio, which is also a gram-negative, comma-shaped bacilli Bacilli Shigella
• Fastidious Fastidious Bordetella growth requirements: CO₂-enriched environment
• Oxidase Oxidase Neisseria positive
• Catalase Catalase An oxidoreductase that catalyzes the conversion of hydrogen peroxide to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in acatalasia. Nocardia/Nocardiosis positive: split hydrogen peroxide Hydrogen peroxide A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials. Myeloperoxidase Deficiency into water and oxygen

Clinically relevant species

• C. jejuni
• C. coli
• C. upsaliensis
• C. fetus

Epidemiology

• Campylobacter is the leading cause of acute diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea worldwide.
• Most common in young children and young adults
• Slight male predominance

Pathogenesis

Reservoirs

• C. jejuni: intestinal tract of animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic, primarily poultry
• C. coli: intestinal tract of pigs
• C. upsaliensis: intestinal tract of dogs and cats
• C. fetus: intestinal tract of cattle and sheep

Transmission

• Food contamination (most common):
  • Consumption of raw or undercooked meat
  • Cross-contamination from raw meat
  • Unpasteurized milk
• Water-borne (contaminated unchlorinated water)
• Fecal–oral transmission 
• Direct contact with animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic or carcasses: usually associated with occupational exposure (cattle, dogs, and cats)

Pathogenesis factors

• Bacterial load: higher numbers more likely to produce illness
• Virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus:
  • Flagella Flagella A whiplike motility appendage present on the surface cells. Prokaryote flagella are composed of a protein called flagellin. Bacteria can have a single flagellum, a tuft at one pole, or multiple flagella covering the entire surface. In eukaryotes, flagella are threadlike protoplasmic extensions used to propel flagellates and sperm. Flagella have the same basic structure as cilia but are longer in proportion to the cell bearing them and present in much smaller numbers. Helicobacter: ability to move through mucus
  • Superficial adhesins Adhesins Cell-surface components or appendages of bacteria that facilitate adhesion (bacterial adhesion) to other cells or to inanimate surfaces. Most fimbriae of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (biofilms) is distinct from protein adhesin. Diarrheagenic E. coli, chemotactic factors: mediate attachment to intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy
  • High-molecular-weight plasmids Plasmids Extrachromosomal, usually circular DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in genetic engineering as cloning vectors. DNA Types and Structure: increase invasiveness
• Host immunity:
  • Primarily humoral (immunoglobulin A ( IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions), IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions, IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis, complement)
  • May generate autoimmune response through molecular mimicry Molecular Mimicry The structure of one molecule that imitates or simulates the structure of a different molecule. Rheumatic Fever

Clinical Presentation

Gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis

• Abdominal pain Abdominal Pain Acute Abdomen/cramping
• Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
• Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
• Bloody diarrhea Bloody diarrhea Diarrhea, especially in children. 
• Incubation Incubation The amount time between exposure to an infectious agent and becoming symptomatic. Rabies Virus period: 3 days
• Duration: self-limited, lasts approximately 7 days
• Treatment: supportive

Complications (autoimmune)

• Guillain-Barré syndrome Guillain-Barré syndrome Guillain-Barré syndrome (GBS), once thought to be a single disease process, is a family of immune-mediated polyneuropathies that occur after infections (e.g., with Campylobacter jejuni). Guillain-Barré Syndrome:
  • Usually occurs 1–2 weeks after onset of diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • Symmetric ascending paralysis due to molecular mimicry Molecular Mimicry The structure of one molecule that imitates or simulates the structure of a different molecule. Rheumatic Fever of peripheral, Schwann cells
• Reactive arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis:
  • Classic triad: conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis, urethritis Urethritis Inflammation involving the urethra. Similar to cystitis, clinical symptoms range from vague discomfort to painful urination (dysuria), urethral discharge, or both. Urinary tract infections (UTIs), arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis
  • Usually occurs 1–2 weeks after onset of diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • More commonly associated with HLA-B27 phenotype Phenotype The complete genetic complement contained in the DNA of a set of chromosomes in a human. The length of the human genome is about 3 billion base pairs. Basic Terms of Genetics

Prevention

• Primarily through safe food-handling practices
  • Cooking poultry to proper temperatures
  • Avoiding cross-contamination
• Hand-washing practices for anyone with diarrheal illnesses or direct contact with farm animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic