Campylobacter
Campylobacter is a genus of bacteria belonging to the family Campylobacteraceae. Species of this genus are comma-shaped, Gram-negative bacilli that are mobile due to the presence of one or two polar flagella. They measure between 0.5 and 5 microns long by 0.2 to 0.5 microns wide, taking a coccoid shape in old cultures or prolonged exposure to air.
Features
They are not sporulated, they react positively to oxidase, the reaction to catalase is variable, and their optimal growth temperature ranges between 25 and 42 °C. Colonies of this genus do not usually show pigmentation and have microaerophilic respiratory metabolism (3-5% O2) with a low degree of oxygen 5%, carbon dioxide 10% and 85% nitrogen. Campylobacter culture media are nutrient-enriched media such as Preston 1/10 and Park-Sanders 1/10, and in some cases grown at 42 °C. Due to their flagellum, they are very mobile organisms, with a peculiar movement due to their morphological shape, like the Helicobacter, they move in the shape of a corkscrew. They are destroyed by chlorination and pasteurization. They have a characteristic morphology when observed under a microscope, in the shape of an "S", "comma", or also called "seahorse".
Growing
The genus Campylobacter constitutes a group of microorganisms that require selective culture media, such as Skirrow's agar -consisting of 10% human blood and a supplement of several antibiotics, and "BAP of Campy". The incubation of the plates seeded with these organisms must be carried out in an atmosphere with 10% CO2 and 5% O2, which grow best between 37 and 42 °C for 48 hours.
Pathogenesis
At least a dozen Campylobacter species have been implicated in human disease, and C. jejuni and C. coli are the most common. Campylobacter jejuni is now one of the leading causes of food poisoning in many developed countries. Campylobacteriosis is an infectious disease caused by bacteria of the genus Campylobacter. C. fetus is a cause of spontaneous abortions in cattle and sheep, and is also an opportunistic pathogen in humans.
Clinical picture
The infection caused by Campylobacter has an incubation period of two to five days, and is manifested mainly by the appearance of fever, abdominal pain, and diarrhea. Rarely, post-infectious complications can lead to reactive arthritis, Guillain-Barré syndrome (a severe form of paralysis), etc. Transmission can occur through direct contact with contaminated food or water, through human-to-human contact, or through contact with infected animals..
Genome
The genome of several Campylobacter species has already been sequenced, which has provided insights into the mechanisms that allow them to cause pathogenicity. The Campylobacter species contain two genes of flagellin one after the other (in tandem), called flaA and flaB, which provide motility to the microorganism. Inactivation of the two genes separately by a mutagenesis method known as homologous recombination allowed us to determine that one of the two flagellin genes (flaA) is necessary for invasion and that flaB is poorly expressed within Campylobacter. Both genes, despite being in tandem are transcribed by different promoters although they are transcribed concomitantly, in fact the expression of only flaB, and not its homologue flaA, causes the bacterium to be immobile. These genes undergo both intragenomic and intergenomic recombination, further contributing to the virulence of the bacterium. bacteria. Immobile strains are not colonizers.
Taxonomy
To date the genus is composed of more than 17 species and 7 subspecies of Campylobacter. The following species were changed gender in recent years:
- Campylobacter pyloridis -... currently known as Helicobacter pylori.
- Campylobacter cryaerophila -- currently known as Arcobacter cryaerophilus.
- Campylobacter nitrofigilis -- currently known as Arcobacter nitrofigilis.