Understanding infections during cancer treatment

4 March 2025
Amina Sabjee

Understanding infections during cancer treatment

Cancer treatments weaken your immune system making you susceptible to infections caused by harmful microorganisms that get in and multiply in your body. Some infections may develop into life-threatening sepsis if your immune system cannot effectively fight off the infection.

Awareness of these infections, their symptoms, and the precautions you can take can greatly assist you in your journey to better health.

list of the most common infections

Bacteria are the most common cause of infections and are usually mild but are exacerbated in persons with a lowered immune system.

Staphylococcus epidermis (affects mainly your skin) and Staphylococcus aureus are common Staph infections. Staphylococcus epidermis bacteria is commonly found around central lines such as a peripherally inserted central catheter (PICC line).
Methicillin-resistant Staphylococcus Aureus (MRSA) infections are resistant to standard antibiotics however can be treated with vancomycin.
Streptococcus bacteria, often called Strep, cause tonsillitis and skin infections like cellulitis which can be treated with penicillin.
Pneumococcal pneumonia is caused by a type of Strep as well. This causes a chest infection and is commonly also found in central lines.
Enterococci cause bladder infections and blood poisoning.
Pseudomonas lives in soil, water and skin and although is not as common, it can be problematic for people with weak immune systems who are in hospital for lengthened periods.
Clostridium difficile is found in your gut and in the right numbers is healthy, however prolonged use of antibiotics disturbs the balance of this bacteria resulting in excessive amounts that are harmful to you. This causes abdominal pain, diarrhoea, fever and loss of appetite.

Escherichia coli (E.Coli) affect gut health as well and display the same symptoms as the Clostridium difficile bacteria.
Listeria monocytogenes, known as Listeria, is caused by eating contaminated food.
The common cold virus may cause pneumonia in persons with a weakened immune system.
Influenza is a virus that is constantly changing.
The Herpes simplex virus causes cold sores and genital herpes.
Varicella zoster, a relative of the Herpes virus, causes chickenpox. If a person has had chickenpox before you are susceptible to Shingles which affect the nerves and the skin.
Cytomegalovirus (CMV) is another common virus that causes multiple infections such as chest infections after stem cell or bone marrow transplants.
COVID-19 may cause mild symptoms such as flu or a more serious respiratory infection.

There are certain viruses that, after contraction and treatment remain dormant in your body until your immune system is too weak where there is a possibility that it may reactivate.

Fungal Infections
Interestingly, Fungi live in your body as well, without causing any problems, unless of course your immune system is weakened. Thrush is a common fungal infection you may be at risk for. Less common fungal infections include Aspergillus which causes chest infections, and Pneumocystis which causes a form of pneumonia.

Protozoal Infections
Protozoa are single-celled organisms that cause mild illness in healthy persons, however, may cause infections that affect the brain in persons with a compromised immune system.

Symptoms

The symptoms are vast and any changes in your general health should be mentioned to your doctor as a precaution. You can however look out for some of the symptoms below:

Flu symptoms – high or low temperatures, aching muscles, coughing, headaches, a sore throat, coughing up green phlegm.
Unable to get out of bed, feeling dizzy or faint, and skin changes (redness, sensitivity)
Painful urination or foul-smelling urine.
Nausea or Diarrhoea
Pain, swelling, redness, discharge or heat at the site of a wound or central line
Pain anywhere in your body that was not there before your treatment.
A rapid heartbeat
Mouth ulcers

Symptoms of Sepsis can be remembered by its name:

S – Slurred speech, confusion

E -Extreme shivering, muscle pain

P – Passing no urine (in a day)

S – Severe breathlessness

I -It feels like you’re going to die

S – Skin mottled (spotty) or discoloured

Preventative Measures

It is not always possible to prevent an infection however, there are steps you can take before your treatment to lower your risk of infections.

Pre-Treatment:

Have a dental check-up to ensure that there are no preexisting dental conditions (bacterial or viral) that may increase your risk for infection.

Hygiene:

Brush your teeth at least twice a day or after meals with a soft toothbrush.

Wash your hands regularly, before meals, after meals, before preparing meals, after using the bathroom, after every contact with an animal even your fluffy cat or gentle parrot.

Food Safety:

Always prepare fresh meals and cook food following the correct instructions (This ensures that the least amount of bacteria will be on your food)

Reduce your risk by avoiding prepacked/dried meats, soft cheeses or patés, smoked fish, sushi, prepared cooked meals and sandwiches and unpasteurised milk.

Avoid exposure:

Stay away from persons who are ill in any way even if it is just a mild flu. Protect yourself from getting scratches and always use an antiseptic cream and cover over any wounds with a plaster.

Treatment:

The medical professionals will know how to treat infections (The correct drug and dosage as well as the administering of the treatment)

It is important to note that drug resistance for bacterial and viral infections (by bacterial and viral mutations) is a growing concern globally. This may lead to longer illnesses, increased mortality, and more expensive treatments. Improved practices in prescribing antibacterial and antiviral drugs, increased research, and heightened public awareness are essential to mitigate this growing challenge.

Disclaimer:

The information provided here is for general informational purposes only and should not be construed as medical advice. While efforts have been made to ensure the accuracy and reliability of the information presented, it is not intended to replace professional medical consultation, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment. Never disregard professional medical advice or delay in seeking it because of something you have read here. If you are experiencing a medical emergency, call your doctor or emergency services immediately.

References

Amanda Delgado, A. K. (2021). Infections in Hospitalized Cancer Patients. Pbmed central, World Journal of Oncology, 195-205. Retrieved from:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8734501/

Amar Safdar, G. B. (2011). Infections in Patients with Cancer: Overview. Pudmed Central, Springer Nature,Principles and Practice of Cancer Infectious Diseases, 3-15. Retrieved from:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7122113/

cancerresearchuk. (2023, February 17). Retrieved from www.cancerresearchuk.org:
https://www.cancerresearchuk.org/about-cancer/coping/physically/fever/causes/infection/types

cancerresearchuk. (2023, August 7). Retrieved from https://www.cancerresearchuk.org:
https://www.cancerresearchuk.org/about-cancer/coping/physically/sepsis-infection-cancer

CDC. (2024, April 17). Retrieved from https://www.cdc.gov/:
https://www.cdc.gov/antimicrobial-resistance/prevention/index.html

Department of Helath, New York State. (2012, February). Retrieved from www.health.ny.gov:
https://www.health.ny.gov/diseases/communicable/staphylococcus_aureus/methicillin_resistant/fact_sheet.htm

WHO. (2023, November 21). Retrieved from https://www.who.int/:
https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance