Campylobacterota represents a significant phylum of bacteria widely distributed in various natural environments. This diverse group includes both beneficial symbionts and various pathogens. They are characterized by specific biological features and play roles in different ecosystems.
Understanding the Taxonomic Difference
It is common to confuse a bacterial phylum with a genus, but these terms represent distinct levels in scientific classification. Campylobacterota is a phylum, a high-level grouping that encompasses many different classes, orders, families, and genera of bacteria. For example, Campylobacter and Helicobacter are well-known genera within the phylum Campylobacterota.
The phylum Campylobacterota was reclassified in 2021, having previously been part of the Proteobacteria phylum as Epsilonproteobacteria. This taxonomic revision helps scientists better understand evolutionary relationships between different bacteria. The current accepted taxonomy is based on established systems like the List of Prokaryotic names with Standing in Nomenclature (LPSN) and the National Center for Biotechnology Information (NCBI).
General Characteristics and Habitats
Bacteria within the Campylobacterota phylum share several common biological features. They are all Gram-negative, meaning they do not retain the crystal violet stain. Many species are motile, possessing flagella for movement. Their morphology often includes curved, spiral, or S-shaped rods.
These bacteria are often microaerophilic, requiring oxygen at lower concentrations than found in the atmosphere. They are found in diverse natural habitats, including the digestive tracts of various animals, such as humans and livestock. Some Campylobacterota species can also thrive in water sources, deep-sea hydrothermal vents, and other environmental niches, utilizing unique metabolic pathways like oxidizing reduced sulfur or hydrogen.
Key Pathogenic Members and Their Diseases
Within the Campylobacterota phylum, two genera, Campylobacter and Helicobacter, are known for causing diseases in humans. Campylobacter species, especially Campylobacter jejuni and Campylobacter coli, are leading causes of bacterial foodborne illness globally. In Europe, over 246,000 cases of Campylobacter infection are confirmed annually.
The disease caused by Campylobacter is known as campylobacteriosis, characterized by symptoms such as diarrhea, which can sometimes be bloody, abdominal pain, fever, and vomiting. Symptoms typically appear 2 to 5 days after exposure and usually last for 3 to 6 days, though abdominal pain can persist longer. In rare instances, C. jejuni infection has been linked to Guillain-Barré syndrome, a serious neurological disorder, and reactive arthritis.
The Helicobacter genus includes Helicobacter pylori, a bacterium that infects the stomach lining. H. pylori is a primary cause of peptic ulcers, which are sores in the lining of the stomach or small intestine. While many infected individuals do not experience symptoms, the infection can lead to chronic inflammation of the stomach lining, known as gastritis. H. pylori infection also increases the risk of developing certain types of stomach cancer. Symptoms of H. pylori infection, when present, can include stomach pain or burning, bloating, nausea, vomiting, indigestion, and loss of appetite.
Preventing and Treating Infections
Infections caused by pathogenic Campylobacterota are often transmitted through contaminated food and water, and sometimes through direct contact with infected animals or people. For Campylobacter, raw or undercooked poultry is a frequent source, as these bacteria commonly reside in the intestines of healthy birds. Unpasteurized milk and untreated water are also common transmission routes. For Helicobacter pylori, transmission is less clear, but it is thought to spread through direct person-to-person contact, particularly mouth-to-mouth, or through contaminated food and water.
Prevention strategies focus on reducing exposure to these bacteria. Safe food handling practices are important, including thoroughly cooking meat, especially poultry, and avoiding cross-contamination between raw and cooked foods. Proper hygiene, such as washing hands with soap and water before eating and after contact with animals or using the bathroom, is also important. Ensuring access to safe, treated drinking water and consuming pasteurized milk and juices further minimizes risk.
Treatment for Campylobacter infections generally involves rehydration therapy to replace fluids lost due to diarrhea, as most cases are self-limiting and resolve within about a week. Antibiotics are typically not required, but may be prescribed for severe or prolonged cases, or for individuals with weakened immune systems, pregnant individuals, or the elderly. For Helicobacter pylori infections, treatment usually involves a combination of antibiotics to kill the bacteria and acid-reducing medications to help heal the stomach lining. It is common to take multiple types of drugs, including two or more antibiotics, for one to two weeks.