- Not all bacteria are harmful.
- Bacterial infections are one cause of infectious diseases.
- Serious bacterial infections can be treated with antibiotics.
- Antibiotic resistance is a serious problem.
What are bacterial infections?
A bacterium is a single, but complex, cell. It can survive on its own, inside or outside the body.
Most bacteria aren’t harmful. In fact, we have many bacteria inside our body and on our skin. Bacteria in our intestines (gut) help us to digest our food.
But some bacteria can cause infections. Bacterial infections can affect many parts of your body, including your:
Many infections are mild, but some are severe.
Some examples of bacterial infections are:
- Legionnaires’ disease
- meningococcal disease
- Q fever
- strep throat
- tuberculosis (TB)
- whooping cough (pertussis)
Other causes of infectious diseases are viruses, parasites and fungi.
What are the symptoms of a bacterial infection?
The symptoms of a bacterial infection depend on the location of your infection and the type of bacteria involved.
There are some general signs of bacterial infection:
- feeling tired
- swollen lymph nodes in your neck, armpits, groin or elsewhere
- nausea or vomiting
CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.
What causes bacterial infections?
Bacterial infections occur when bacteria enter your body. Once in your body they increase in number. This causes an immune reaction in your body.
Bacteria can enter your body through:
- a cut on your skin
- eating or drinking contaminated food or water
- breathing in droplets from an infected person
- touching dirty surfaces and then touching your eyes, nose, or mouth
Bacteria can also be transmitted by contact with blood and other bodily fluids.
Bacterial infections and weather events
The risk of getting a bacterial infection increases when you are in contact with flood water. Flood water can come from storms or cyclones.
Touching items affected by flooding can also increase your risk of bacterial infection. You should avoid contact with flood water and practice good hand hygiene. Wash your hands with soap and clean water. If clean water isn’t available, use hand sanitiser.
When should I see my doctor?
Signs that you have a bacterial infection depend on the type of bacteria and the part of your body that is infected. You should see your doctor if you have:
- a persistent fever or chills
- severe headache or neck stiffness
- eye redness and crusting (pus)
- persistent ear pain or wetness (discharge)
- persistent facial pain and runny nose
- difficulty breathing
- a persistent cough, or coughing up blood or pus
- frequent vomiting and trouble holding liquids down
- severe stomach pain
- blood or mucus in your poo (stool)
- discomfort when urinating (doing a wee) or urine that is smelly, cloudy or contains blood
- any abnormal genital discharge
- unexplained skin redness or swelling
- a skin wound that is red, hot, swollen, or has pus
- a rash that doesn’t fade when you press it
- difficulty eating or drinking
- unexplained weight loss
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How are bacterial infections treated?
Your doctor’s choice of antibiotic will depend on the bacteria that is causing your infection.
Antibiotics that work against a wide range of bacteria are called broad-spectrum antibiotics.
Antibiotic resistance is a growing problem so antibiotics must always be used appropriately and as prescribed.
How can bacterial infections be prevented?
Bacterial infections can be highly contagious. Bacterial infections are spread between people through:
- bodily fluids, from sex or sharing dirty needles
You need to take special care to avoid spreading infections by:
- washing your hands properly
- covering up when sneezing and coughing
- not sharing cups and drink bottles
- having safe sex
- not sharing needles
Complications of bacterial infections
It’s important to seek treatment because untreated bacterial infections can lead to serious problems. For example, an untreated infected cut can cause cellulitis, a spreading skin infection.
Untreated bacterial infections can sometimes lead to serious, life-threatening conditions.
- Septicaemia is a serious blood infection. It is when bacteria enter the bloodstream and cause blood poisoning.
- Sepsis is a condition that happens when the body damages its own tissues in response to a bad infection. Sepsis can cause shock, organ failure and death if it’s not treated quickly.
Sepsis is a medical emergency and can be fatal if not treated quickly. If you suspect you or someone else has sepsis, call triple zero (000) for an ambulance.
Ask your doctor ‘Could this be sepsis?’ if:
- you are feeling very unwell
- you are not getting better from a generalised illness
- you are quickly getting worse
- there is any chance of an infection
- you are more concerned about your child than you normally are when they are sick
Resources and support
You can download the app Could this be sepsis? from the Australian Sepsis Network (ASN), to check your symptoms.
You can find out more about what Australia is doing to limit antimicrobial resistance here.
You can call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: December 2022