A bacterial infection is an infection caused by bacteria. It can occur anywhere in or on the body. The infection often leads to pain, general discomfort, and occasionally fever. If the infection is prolonged and severe, antibiotics are used to eliminate the bacteria.
Bacterial infections

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What is a bacterial infection?
Infections can occur when bacteria present in our bodies multiply. Although bacteria are invisible to the naked eye, we encounter them daily. However, we do not always become unwell. This is because our immune system protects us, and not all bacteria are harmful; in fact, our bodies contain bacteria that carry out beneficial functions.
For instance, they assist in digesting food in our intestines and help protect our skin from harmful invaders.
When harmful bacteria enter the body, our immune system responds by producing more white blood cells to defend against infection. However, if the bacteria multiply faster than our body can produce white blood cells, we may fall ill. This can lead to infections such as pneumonia.
Such infections are often accompanied by fever. Conditions like pneumonia or endocarditis can be life-threatening if antibiotics are not administered. In these cases, the body is unable, or only barely able, to recover on its own. Antibiotics can therefore be crucial in saving lives. That said, in some instances, bed rest or other simple measures may suffice to recover from a bacterial infection.
The choice of antibiotic depends on the symptoms and the type of bacterial infection. In certain cases, it may be necessary to send a sample of urine or pus to a laboratory to identify the bacterium causing the infection and determine the appropriate antibiotic. Each bacterium has a unique structure.
How do you contract a bacterial infection?
Bacterial infections are caused by bacteria. The way you contract a bacterial infection depends on the type: it may occur through the respiratory tract, contaminated food, the urethra, or a minor wound in the skin. A bacterial infection can also arise in an area where bacteria are normally already present.
Is a bacterial infection contagious?
Whether a bacterial infection is contagious depends on the type of bacteria and the location of the infection. Some bacteria can be spread through coughing or sneezing, contact with hands, contaminated food, or wound fluid. Other bacterial infections are barely contagious.
The length of time a bacterial infection remains contagious varies depending on the specific infection. In cases of fever, diarrhoea, coughing, or an inflamed wound, maintaining good hygiene is essential: wash your hands, cover wounds, and avoid sharing towels.
What types of bacterial infections are there?
The most common bacterial infections include:
- Pneumonia;
- Throat infection;
- Middle ear infection;
- Bladder infection;
- Skin infections;
- Intestinal infection;
- Eye infection.
Pneumonia
Pneumonia involves inflammation of the smaller airways and alveoli. Those affected by pneumonia may experience coughing, shortness of breath, fever, and fatigue. Pneumonia can be caused by either a bacterium or a virus, with the flu virus often being responsible in viral cases.
This condition results in an accumulation of mucus in the alveoli, reducing oxygen absorption and leading to shortness of breath. If pneumonia is bacterial, your doctor will prescribe a course of antibiotics. It is often not immediately clear whether the cause is viral or bacterial.
Throat infection
A throat infection can also be caused by either a virus or a bacterium. Common symptoms include pain or a burning sensation in the throat, pain when swallowing, fever, swollen glands, a hoarse voice, and sometimes ear pain. In cases of bacterial throat infections, the tonsils are inflamed, which is typically caused by the streptococcus bacterium and is often very painful.
Middle ear infection
A middle ear infection, also referred to as ear pain, is most commonly seen in children under the age of five. It usually resolves on its own within two to three days. The infection may be caused by the common cold virus entering the middle ear or by a bacterium such as *Streptococcus pneumoniae* that has settled in the middle ear. The increased pressure in the middle ear causes the eardrum to bulge, which can be very painful.
Bladder infection
A bladder infection occurs when the lining of the bladder becomes inflamed. This is often caused by bacteria from the intestines entering the bladder through the urethra, leading to an infection. Women are more susceptible to bladder infections than men due to their shorter urethra.
Bacterial skin infection
A bacterial skin infection typically develops where the skin has been damaged. Bacteria that are normally present on the skin enter through the damaged area, causing inflammation. Examples of bacterial skin infections include erysipelas and impetigo. Symptoms of a bacterial skin infection include redness, swelling, pain, or pus.
Intestinal infection
Inflammation of the intestinal wall can be caused by a virus or bacterium, impairing the intestine's ability to absorb fluids and nutrients. This results in very watery stool. Gastrointestinal infections may be caused by viruses (such as stomach flu), parasites, or bacteria like Salmonella.
Eye infection
The most common type of eye infection is conjunctivitis, which is an inflammation of the conjunctiva. This is the thin tissue covering the white part of the eye and the inside of the eyelids. An eye infection can be caused by either a virus or a bacterium.
How to recognise bacterial infections?
Symptoms of a bacterial infection include pain, fatigue, red or swollen skin, a general feeling of malaise, and occasionally fever. Swollen lymph nodes may also occur, for instance, in cases of a throat infection or tonsillitis. Additionally, you might experience flu-like symptoms such as muscle pain and a reduced appetite.
The symptoms of a bacterial infection vary depending on its location in the body. A bacterial presence can lead to issues in the respiratory tract, skin, bladder, intestines, or eyes. Contact a doctor if symptoms worsen or persist for an extended period.
Can I do anything myself to combat bacterial infections?
To tackle a bacterial infection, it is always sensible to rest and ensure you stay well-hydrated by drinking plenty of fluids. Will a bacterial infection resolve on its own? Occasionally it might, but this depends on the type of infection, the strength of your immune system, and how severe the symptoms are.
If your symptoms worsen or persist, or if you develop a fever, contact your GP. They will examine you and may prescribe antibiotics to treat the infection and eliminate the bacteria.
What are the treatments?
If your doctor determines that the infection is caused by bacteria, they will prescribe an antibiotic. Treatment for a bacterial infection may also involve rest and ensuring you stay well-hydrated.
Fighting bacterial infections with antibiotics
Antibiotics are categorised as either narrow-spectrum or broad-spectrum. Narrow-spectrum antibiotics are specifically designed to target infections caused by a particular group of bacteria. Broad-spectrum antibiotics, on the other hand, are effective against multiple types of bacteria at once. Doctors generally prefer to prescribe narrow-spectrum antibiotics as they affect fewer beneficial bacteria, which helps to minimise side effects.
However, narrow-spectrum antibiotics can only be prescribed if the specific bacteria causing the infection have been identified. If this is not possible, broad-spectrum antibiotics may be used as an alternative. The drawback of broad-spectrum antibiotics is that they are more likely to cause side effects, such as gastrointestinal problems, as they also impact the beneficial bacteria in the gut flora.
The location of the infection within the body is another crucial factor when selecting an antibiotic. Certain tissues are more or less responsive to specific types of antibiotics. The doctor must choose an antibiotic capable of penetrating the affected tissue effectively.
Antibiotics are always prescribed by a doctor and only when absolutely necessary, such as when your immune system is not strong enough to combat the infection on its own. This cautious approach is aimed at preventing antibiotic resistance. Resistance occurs when bacteria adapt and become unresponsive to the effects of the medication.
As a result, this particular antibiotic may no longer be effective in treating the bacteria, even in other patients.
Antibiotic resistance
Bacteria can also gradually develop resistance, particularly with repeated or prolonged use of the same type of antibiotic. Antibiotic resistance can lead to serious consequences; in the worst-case scenario, bacterial infections may become untreatable in the future, which could be life-threatening in some cases.
Since antibiotics are only effective against bacteria and not viruses, doctors will not prescribe them for illnesses such as the flu, a cold, or chickenpox. Always follow your doctor’s instructions when taking antibiotics and ensure you complete the full course, even if you start feeling better. Failing to do so may result in the infection returning. A typical course of antibiotics lasts between 5 and 10 days, depending on the type of infection.
Additional risks and side effects
In general, antibiotics cause few side effects, particularly narrow-spectrum antibiotics. Side effects are more commonly associated with broad-spectrum antibiotics, as these can also eliminate beneficial bacteria in the gut. However, loose stools are not always a side effect of the medication; they may also be a symptom of the underlying infection.
The most common side effects of antibiotics include:
- Diarrhoea or loose stools;
- Hypersensitivity or allergic reactions.
If you are hypersensitive to a specific antibiotic, you may experience red spots on the skin, itching, or fever. While these symptoms could indicate an allergy, this is not always the case. In such instances, it is important to consult a doctor, who can determine whether the symptoms are due to hypersensitivity to the antibiotic you are taking.
Antibiotics from the tetracycline group, such as doxycycline and minocycline, may cause sensitivity to sunlight, making you more susceptible to sunburn. If this occurs, it is advisable to minimise sun exposure and use a sunscreen with a high protection factor to protect your skin.
If you are aware of any hypersensitivity to an antibiotic, inform your doctor. Furthermore, if you experience other symptoms that persist for more than one or two days, it is recommended to seek medical advice.
How long does a bacterial infection last?
The duration of a bacterial infection varies depending on the type of bacteria, the location of the infection, and your overall health. Some symptoms may improve within a few days, while other infections might require treatment. Always ensure you complete a prescribed course of antibiotics.
How can you prevent bacterial infections?
It is often not entirely possible to prevent bacterial infections. However, there are steps you can take to lower the risk of certain infections. For example, it is well established that individuals who smoke and consume alcohol regularly are at a greater risk of developing pneumonia.
You can also support your immune system to keep it strong, allowing your body to more effectively eliminate harmful bacteria that may enter it. Furthermore, you can reduce the risk of contamination with Salmonella bacteria by practising good hygiene and washing your hands frequently. Disinfecting minor skin wounds with iodine or alcohol can also help prevent skin infections.
site.skiplink.go-to-faq-itemsWhat are the symptoms of a bacterial infection?
How long does a bacterial infection last?
Frequently asked questions
What are the symptoms of a bacterial infection?
Possible symptoms include nausea, fever, headache or exhaustion, and sometimes dehydration.
How long does a bacterial infection last?
An infection can last anything from a few days to several months. Sometimes it clears up on its own, but in many cases treatment with antibiotics or other medication is required.
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