Bacteria can enter the body through the nose, mouth, eyes, or skin. Once the bacteria enter the body, they begin multiplying. Each bacterium divides into two. Under ideal conditions, a single bacterium can produce 72 billion bacteria in just 12 hours.
The bacteria release harmful toxins into the body, which cause symptoms of infection. Symptoms worsen as the number of bacteria increase.
An infection is suspected if a patient has a fever, swelling, and/or pain. Some infections, such as cellulitis, can be diagnosed after the healthcare provider evaluates the patient's signs and symptoms during a physical examination.
Most bacterial infections are diagnosed after the bacteria are identified in the patient's blood or tissue. The healthcare provider will take a small sample of tissue from the affected area. The sample is then analyzed under a microscope for the presence of bacteria. For instance, if the patient's symptoms involve the respiratory tract, a healthcare provider may use a swab on the back of the patient's throat. The cells that are collected on the swab are then analyzed for bacteria.
signs and symptoms
General: Symptoms vary depending on the type and severity of the infection, as well as the parts of the body that are infected. In general, most infections cause swelling, redness, fever, and pain. Patients should visit their healthcare professionals if any of these symptoms develop.
Blood (sepsis): A bacterial infection from virtually any part of the body can potentially enter the bloodstream. When this happens, the condition is called sepsis. Symptoms typically include fever, severe shaking, low blood pressure, and coma. If the condition is not treated quickly, sepsis can lead to organ dysfunction and death.
Sepsis is a leading cause of death mostly in the elderly or chronically ill in the United States, killing an estimated 215,000 Americans each year.
Eyes: Bacteria can also infect the eyes. This condition is commonly called pinkeye or conjunctivitis. Common symptoms include redness, irritated and watery, itchy eyes, blurred vision, and discharge that forms a crust during sleep. Other less common symptoms may include pain and sensitivity to light.
Digestive tract: Bacterial infections, including those caused by Staphylococcus aureus or Escherichia coli (E. coli), can develop in the digestive tract if a patient consumes food or beverages that are contaminated with disease-causing bacteria. This type of infection is commonly known as food poisoning. Common symptoms of digestive tract infection include upset stomach, abdominal cramping, vomiting, and diarrhea.
Nervous system: Bacterial infections, such as bacterial meningitis, can affect the body's nervous system, which includes the brain and spinal cord. Common symptoms of bacterial infections of the nervous system include severe headache or back pain, weakness, sensory loss, and a fever. An individual may report a stiff neck, nausea or vomiting, tiredness, and disorientation. In severe cases, patients may experience seizures, paralysis, coma, or death.
Respiratory tract: Bacterial infections can develop in the respiratory tract, which includes the nose, sinuses, throat, and lungs. Symptoms may include fever, chills, difficulty breathing, chest pain, stuffy nose, congestion, sore throat, increased heartbeat, fatigue, and general feeling of discomfort.
Skin: If bacteria causes an infection of the skin, common symptoms include reddening of the skin, swelling, pain, rash, blisters, and skin discoloration.
Urinary tract: Bacteria may infect the urinary tract, which includes the kidneys, the tubes that carry urine from the kidneys to the bladder (ureters) bladder, and tube that carries urine out of the body (urethra). Common symptoms of urinary tract infections include strong urge to urinate, burning sensation when urinating, frequently passing small amounts of urine, blood in the urine, or cloudy, strong-smelling urine.
Vagina: When bacteria cause an infection in the vagina, it is called bacterial vaginosis. The most obvious sign of the condition is an unpleasant odor. Other symptoms often include itching and/or burning sensation near the vagina.
Antibiotic resistance: Antibiotic resistance occurs when antibiotics are not effective against specific disease-causing bacteria. This is more likely to occur in individuals who receive antibiotics often than those who do not. If a patient becomes infected with antibiotic resistant bacteria, he/she may need to take different types of antibiotics that are less effective than the standard treatment.
Organ damage and death: If bacterial infections are not treated, they can spread to other areas of the body. In some cases, the bacteria can lead to organ damage and death. Infections in the blood are especially dangerous. Once the bacteria are in the bloodstream, the infection can spread to virtually any area of the body. In order to avoid complications of bacterial infections, patients should visit their healthcare providers if they develop any symptoms of an infection.