Bacterial infections
medical conditions

Bacterial infections

Explore the available health information, treatment context, and integrative evidence for Bacterial infections.

Background
  • Some microscopic organisms called bacteria can cause diseases in humans. When this occurs, it is called a bacterial infection.
  • There are thousands of different types of bacteria that live around the world. Only a few types of bacteria cause disease in humans.
  • Some bacteria are actually beneficial for humans. For examples, bacteria help humans digest certain types of food and keep infectious organisms at bay. Bacteria may be found in the environment, on the skin, in the airways, in the mouth, in the vagina, and in the digestive tract.
  • Disease-causing bacteria can cause an illness in humans when they enter the body. The bacteria may enter the body through the skin, nose, eyes, vagina, or mouth. Once the invading bacteria start to multiply and harm the body, it is called an infection. Infections can develop in any area of the body.
  • In some cases, the bacteria in the digestive tract, called the intestinal flora, can cause a severe infection if they move into the bloodstream. This process, called bacterial translocation, is most likely to occur during surgery on the digestive tract.
  • When the bacteria enter the body, they begin multiplying. If the infection is not treated, it may spread to other areas of the body. Bacteria cause different diseases depending on the specific type of bacteria and where they are in the body. Examples of bacterial infections include cellulitis, cholera, Fournier's gangrene, methicillin-resistant Staphylococcus aureus (MRSA), trachoma, and tuberculosis.
  • If left untreated, some bacterial infections may lead to death. However, if diagnosed and treated quickly, most patients with bacterial infections experience a complete recovery. Bacterial infections are treated with medications called antibiotics. Depending on the type and severity of the infection, as well as the patient's overall health, antibiotics may be taken by mouth, applied to the skin, or injected into the vein.
Risk Factors and Causes
  • 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.
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.
Diagnosis
  • 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.
Complications
  • 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.
Treatment
  • General: Bacterial infections are treated with medications called antibiotics. Depending on the type and severity of the infection, as well as the patient's overall health, antibiotics may be taken by mouth, applied to the skin, or injected into the vein. Antibiotics are also available as eye drops. If a patient is infected with a different type of microorganism, such as a virus or a fungus, antibiotics will not be effective. Antibiotics only work against bacteria.
  • Antibiotics are categorized into different drug classes including aminoglycosides, cephalosporins, macrolides, penicillins, quinolones, and tetracyclins. Each drug class destroys bacteria in a different way. For instance, some drugs kill bacteria by interrupting a stage of the bacteria's life cycle. Other drugs may slow down or stop bacteria from multiplying, which then allows the body's immune system to kill the bacteria.
  • Patients should tell their healthcare providers if they are taking any other drugs (prescription or over-the-counter), herbs, or supplements because they may interact with treatment. Patients should take medications exactly as prescribed. Even if symptoms appear to go away, patients should take all of their medication because there may still be bacteria in the body. Stopping medication early may allow the infection to return. Also, stopping medication early may lead to antibiotic resistance. The few remaining bacteria in the body that survive most of the antibiotic therapy are the most difficult to kill. If the bacteria become resistant to treatment, the medications will no longer be effective if taken in the future.
  • Aminoglycosides: Aminoglycosides are injected into the patient in order to prevent bacteria from growing inside the body. Examples of aminoglycosides include Amikacin sulfate (Amikacin®), gentamicin (Garamycin®), and netilmicin (Netromycin®). These drugs are commonly used to treat many types of bacterial infections that affect the lungs, skin, bones, joints, stomach, blood, and urinary tract. These drugs may cause serious side effects, such as hearing loss, decreased sense of balance, and kidney problems. Serious side effects are more likely to occur in young children and elderly patients.
  • Cephalosporins: Cephalosporins destroy the cell walls of bacteria, eventually causing them to die. Cephalosporins are used to treat a wide variety of infections, including urinary tract infections and respiratory infections. These drugs are usually taken by mouth as a pill or liquid solution. Examples include cephalexin (Keflex®), cefazolin (Ancef®, Kefzol®), cefmetazole (Zefazone®), cefuroxime (Zinacef®, Kefurox®), cefdinir (Omnicef®), and cefepime (Maxipime®).
  • Macrolides: Macrolides, such as erythromycin (e.g. Ery-Tab®, Eryc®, Ilosone®, EryPed®) and azithromycin (Zithromax®) are used to treat many different types of bacterial infections, including trachoma. These drugs prevent bacteria from growing inside the body. These drugs are usually taken by mouth in the form of pills or liquid. However, they may also be injected if the infection is severe. Side effects may include upset stomach, diarrhea, vomiting, stomach cramps, and stomach pain. Side effects are usually mild and they usually lessen over time.
  • Penicillins: Penicillins, such as penicillin V (such as Pen Vee K®) and amoxicillin (Amoxil®), are a group of antibiotics that are used to treat many different types of infections including respiratory infections and skin infections. These drugs are usually taken by mouth in the form of pills or liquid. They may also be injected if the infection is severe. Mild side effects may include mild stomach cramps or upset, nausea, vomiting, and diarrhea. Serious allergic reactions have been reported with use of penicillins. Patients should call their healthcare providers immediately if they develop a skin rash that is itchy or red or if they experience difficulty breathing, chest pain, or dizziness.
  • Quinolones: Quinolones, such as ciprofloxacin (Cipro®), moxifloxacin (Avelox®), levofloxacin (Levaquin®), and ofloxacin (Floxin®), are used to treatment many different types of bacterial infections, including urinary tract infections, skin infections, and respiratory infections such as sinusitis, pneumonia, and bronchitis. These drugs interfere with bacteria's genetic makeup. As a result, the bacteria can no longer multiply in the body. Side effects may include mild stomach pain or upset, nausea, vomiting, diarrhea, dizziness, nervousness, trouble sleeping, a change in sense of taste, or increased sensitivity to sunlight. If patients develop symptoms of an allergic reaction, such as skin rash, difficulty breathing, chest pain, or dizziness, they should call their healthcare providers immediately. Quinolones may cause chest pain or irregular heart beat in some patients. Patients should tell their healthcare providers immediately if they experience these symptoms.
  • Tetracyclines: Tetracyclines (Helidac Therapy®, Sumycin®, Sumycin® Syrup) are used to treat infections of the respiratory tract, sinuses, middle ear, urinary tract, and intestines. These drugs are taken by mouth in the form of pills or liquid. Side effects may include upset stomach, diarrhea, itching of the rectum or vagina, sore mouth, redness of the skin (sunburn), or changes in skin color. Avoid if pregnant or breastfeeding.
Prevention
  • Avoiding close contact with individuals who have contagious illnesses may help reduce the risk of acquiring infections.
  • Practicing good hygiene and regularly washing the hands with soap and water may help reduce the risk of acquiring infections.
  • Antibiotics should only be taken when needed. This helps reduce the risk of developing antibiotic-resistant bacterial infections in the future.
References
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  9. U.S. Food and Drug Administration (FDA). .