Bacteria of the genus Vibrio belong to the gram-negative bacteria. Most bacteria of this species live in water. A well-known pathogen in the family is Vibrio cholerae, the causative agent of cholera.
What are Vibrio bacteria?
Bacteria of the genus Vibrio are also called vibrions. Vibrions are gram-negative bacteria. They can be stained red in the Gram stain. Unlike Gram-positive bacteria, Gram-negative bacteria have a thin peptidoglycan layer of murein. In addition, they are surrounded by an outer cell membrane. The gram-negative vibrios are curved rod bacteria. On their outer wall they have so-called unipolar flagella. Flagella are cell processes that serve as movement organelles for the bacteria. Flagellated bacteria such as vibrios can swim toward target objects or move away from harmful sites. These processes are called positive and negative cabs. Known representatives of the vibrios are Vibrio alginolyticus, Vibrio harveyi, Vibrio parahaemolyticus, Vibrio natriegens, Vibrio cholerae, and Vibrio fischeri. For humans, the pathogens Vibrio cholerae, Vibrio vulnifiucs, and Vibrio parahaemolyticus are dangerous.
Occurrence, distribution, and characteristics
Vibrions are native mainly to fresh and salt water. Thanks to their flagella, the rod-shaped bacteria can move specifically in the water. The pathogen Vibrio cholerae also feels at home primarily in brackish and coastal waters. Ingestion through contaminated water is the main route of infection. The main source of infection is usually inadequately treated drinking water. Food that has come into contact with the contaminated water is also potentially infectious. Fruits and vegetables, for example, are contaminated during fertilization or splashed with contaminated water. Thus, a person can also become infected with cholera by eating food. More commonly, Vibrio cholerae is still found in fish or seafood. Patients who have contracted cholera excrete the pathogen in their stool or vomit. The pathogen can be detected in the stool for several weeks. However, smear infections are a less common source of infection. While the pathogen causing cholera is now more likely to be found in Asia and Africa, Vibrio vulnifiucs also feels at home on the German Baltic coast due to the low salinity and the strong warming. Vibrio vulnifiucs often enters the body through the consumption of seafood and especially through the consumption of oysters. However, the rod-shaped bacteria can also enter the body through open wounds when swimming or wading in contaminated waters. Tiny injuries are sufficient for this. As long as the water is cold, the bacteria are at the bottom of the sea. As soon as the sea warms up to 15 to 20 ° Celsius, they rise and multiply rapidly. The pathogen Vibrio parahaemolyticus also lives in seawater. This pathogen lives mainly in South and North America. Rarely, infections with Vibrio parahaemolyticus also occur in Europe. The primary source of infection is fish and seafood.
Diseases and symptoms
The pathogen Vibrio cholerae causes the serious bacterial infectious disease cholera. However, only about 15 percent of people who contract the pathogen develop cholera. People with blood group AB very rarely develop symptoms. People with blood group 0 are particularly at risk. The first symptoms appear two to three days after contact with the pathogen. Cholera typically progresses in three stages. The first stage is accompanied by sudden onset of vomiting diarrhea. The thin stool is often interspersed with mucus flakes. It is therefore also called rice water stool. Pain rarely occurs. The second stage is characterized by the lack of fluids. A lot of fluid is lost due to the persistent diarrhea. Fluid loss can be as much as 20 liters per day. Due to the loss of water and salt, patients have a high-pitched and very hoarse voice, called vox cholerica. The loss of electrolytes leads to muscle cramps. Patients’ faces are sunken, eyes are sunken. Blood pressure is low, the heart beats very fast. A pulse is barely palpable on the extremities. In the third stage, the body reacts with drowsiness up to coma. The patients are confused. Complications such as pneumonia, parotid gland inflammation or sepsis may occur.Infection with pathogenic strains of Vibrio parahaemolyticus usually results in acute gastroenteritis. This gastrointestinal inflammation is initially manifested by fatigue, nausea and vomiting. After a few hours, diarrhea is added. The stomach symptoms usually subside by then. Depending on the extent of the disease and the damage to the intestinal mucosa, the diarrhea may be bloody. Bowel activity is increased, so crampy abdominal pain may occur. Fever and dizziness are also possible symptoms. If diarrhea or vomiting persists, exsiccosis (dehydration) may result from fluid loss. When the pathogen Vibrio vulnificus enters the body through the digestive tract, vomiting and diarrhea occur. Diarrhea and vomiting are accompanied by severe abdominal pain. The pathogen can also enter the body via minimal injuries. Dermatitis with blisters then develops at the site of entry. The blisters burst quite quickly, leaving bleeding and painful sores. In people with a weakened immune system, life-threatening sepsis can develop within a short time.
