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Immunity and infection prevention

Bacterial infections

The main article (“Bacterial infections”) explains bacteria in general. This topic looks more deeply at where bacterial infections happen in leukaemia, how they are found and the logic of treatment.

Last updated: ~1 min read
Violet and pink bacteria.
Figure 1.Bacteria stain in two colours.

01Short answer

Bacteria are the most common cause of infection during neutropenia. They usually come from the skin and catheters (gram-positive bacteria) or from the gut (gram-negative bacteria). Gram-negative bacteria in the blood can cause severe illness very quickly, which is why fever during neutropenia is treated as an emergency. To find the cause, blood cultures are taken (bacteria are grown in special bottles), and a broad-spectrum antibiotic is started straight away. Once the bacterium and its sensitivities are known, treatment can be narrowed. Antibiotic resistance is a growing problem, so doctors choose antibiotics carefully.

02Simple explanation

Bacteria: the most common cause in neutropenia.

Blood cultures: to find the bacterium.

Broad first, targeted later.

03Scientific explanation

Gram stain: splits bacteria into two big groups; gram-negatives (such as E. coli, Pseudomonas) are especially dangerous.

Resistance: the WHO calls antimicrobial resistance a global threat, which makes the right choice even more important.

04What happens in the body?

Two colours

In the lab, bacteria are stained and split into two groups, which helps guide treatment.

Blood cultures

A culture can take several days, so treatment starts without waiting.

Glowing culture bottles.
Figure 2.Blood cultures find the bacterium.

Key and lock

Once the bacterium is known, a matching antibiotic is chosen.

A key in a bacterium-shaped lock.
Figure 3.The antibiotic is chosen like a key.

05The treatment path for a bacterial infection

Four steps.

Entry — Bacteria reach the blood.1EntryBacteria reach the blood.
Cultures — Samples are taken.2CulturesSamples are taken.
Broad treatment — Started at once.3Broad treatmentStarted at once.
Narrowing — Targeted therapy.4NarrowingTargeted therapy.

06Common sources

SourceTypical bacteria
Skin and catheterGram-positive (staphylococci)
GutGram-negative (E. coli, Klebsiella)
MouthStreptococci
Urinary tractGram-negative

07Key terms

Blood culture
A test that grows bacteria from blood.
Gram stain
A stain that splits bacteria into two groups.
Bacteraemia
Bacteria in the blood.
Empirical treatment
Treatment started before the cause is known.
Sensitivity test
Shows which antibiotic works.

08Key points

  • Bacteria are the most common cause.
  • Gram-negatives worsen quickly.
  • Cultures are taken before treatment.
  • Treatment starts without waiting.
  • Then it is narrowed.
  • Only a doctor chooses antibiotics.

09Frequently asked questions

Why not wait for the result?

Because gram-negative infections can become severe within hours.

Can I take antibiotics at home?

Sometimes, for low-risk cases, your doctor decides; do not start them yourself.

What is resistance?

It is when an antibiotic no longer works against bacteria.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Why not wait for the result?

  2. Can I take antibiotics at home?

  3. What is resistance?

My questions

12Sources

  1. MedlinePlus (U.S. National Library of Medicine). Bacterial Infections
  2. MedlinePlus (U.S. National Library of Medicine). Antibiotics
  3. World Health Organization (WHO). Antimicrobial resistance (fact sheet)
  4. American Cancer Society. Why Are People with Cancer More Likely to Get Infections?
  5. Centers for Disease Control and Prevention (CDC). Neutropenia and Risk for Infection
  6. Blood Cancer UK. Blood cancer and infection
  7. Journal of Clinical Oncology (ASCO and IDSA), 2018. Antimicrobial Prophylaxis for Adult Patients With Cancer-Related Immunosuppression: ASCO and IDSA Clinical Practice Guideline Update
  8. MedlinePlus (U.S. National Library of Medicine). Low white blood cell count and cancer
  9. Cancer Research UK. Sepsis, infection, and cancer
  10. StatPearls, NCBI Bookshelf. Febrile Neutropenia
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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