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Antibiotics for newborn babies

Why does my baby need antibiotics?

Your baby is receiving antibiotics because of risk factors or signs that suggested that your baby may have a bacterial infection. As part of the birth process, all babies go from the sterile environment inside the uterus, protected by mother’s immune system, to the outside world where they encounter numerous bacteria.

Many of these are the normal bacteria that inhabit our skin, mouth, throat and intestines and actually help us to avoid serious infections.

However, some of these bacteria can cause a serious infection in a newborn baby. These bacteria can include:

Group B Streptococcus (GBS)

Approximately 25% of women have these bacteria in the vagina or lower bowel, and they do not usually cause any health problems for the mother. Mostly there are no ill effects for the baby, but 1–2% of newborns exposed to GBS develop a serious infection unless given antibiotics.

Some women are screened for GBS during their pregnancy but even if the screen is negative, GBS can appear later and so baby may need antibiotic treatment if they have other risk factors or signs of infection.

E. coli

This is the most common type of bacteria found in the normal intestine and again, usually causes no problems for the baby. However, E. coli can sometimes cause a serious infection in a mother or baby during, or soon after, birth.


Listeria bacteria are common in the natural environment but due to good standards of food hygiene, they are rarely found in humans. However, if these bacteria are found in mother’s lower intestine or vagina, her baby is at risk of a very serious illness.

Other bacteria

A wide variety of bacteria, including other types of Streptococcus or other bowel bacteria occasionally cause serious infections in babies.


How will I know if my baby has a bacterial infection?

Your baby has had two blood tests.

  1. Full Blood Count—an initial indicator of the presence, or not, of infection.
  2. Blood Culture—provides the most accurate information, but results take 2-3 days

Newborn babies with a bacterial infection can become very sick very quickly. Therefore your baby is being given antibiotics until the test results are available and show that infection is unlikely, or if the tests are positive, until the infection is treated. If a mother has been treated with antibiotics before birth, the blood culture test can be unreliable. In these circumstances, there may be a need to do later blood tests to help determine whether there was evidence of infection or not, and to help decide when the antibiotics should be stopped.

Once the results are available the doctor will discuss them with you and a decision can be made regarding further tests or antibiotic treatment.

How are the antibiotics given?

The antibiotics are most commonly given via a cannula (IV) inserted into a vein in your baby’s arm or leg. The cannula is flushed with sterile saline (salt water) every 6 hours and before and after each antibiotic is given.

The antibiotics that your baby is most likely to be given are amoxycillin and gentamicin. Together these antibiotics are known to work on most types of bacteria that cause an infection. For term babies, amoxycillin is given every 12 hours and gentamicin is given once every 24 hours.

Sometimes, a cannula may be difficult to insert so a Doctor may decide to give an antibiotic which can be injected into a muscle. This injection is usually given in the thigh. The antibiotic is most likely to be ceftriaxone and it is given once every 24 hours. Your baby’s doctor will decide on the most appropriate way to treat your baby.

If the test results come back negative and your baby is well, antibiotics are usually given for 36 to 48 hours but occasionally longer. When the antibiotics are no longer needed a nurse or midwife will remove your baby’s cannula.

Monitoring your baby

Depending on your baby’s condition, they will either be with you in the postnatal ward or be admitted to the Neonatal Critical Care Unit.

A nurse or midwife will take your baby’s temperature every 4 hours. Their heart rate and breathing will be checked at least every 8 hours. The cannula site is also checked every 6 hours.

There can be side effects to any medication. However, short and long term side effects of amoxicillin and gentamicin are very rare in newborns, which is one of the reasons why these antibiotics are commonly used. It is important to report any concerns to the midwife, nurse or paediatric doctor.

Another blood test will also be taken if gentamicin is given for more than 2 days. This blood test will check that your baby is having the correct amount of gentamicin.

Ceftriaxone is not appropriate to use in babies with jaundice, or in very sick babies, because of interaction with certain types of intensive care treatment.

Additional Information

If you would like further information, talk to your midwife or the doctor who is supervising your baby’s treatment.

Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: PI-CLN-430032
Last modified 08/5/2020.
Consumers were consulted in the development of this patient information.
Last consumer engagement date: 06/5/2020
For further translated health information, you can visit healthtranslations.vic.gov.au/ supported by the Victorian Department of Health and Human Services that offers a range of patient information in multiple languages.
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