Antibiotics: When They Help, When They Harm, and How Severity Is Judged

The one question worth asking: bacteria or not?

Antibiotics kill or stop bacteria. They do nothing to viruses. So the central question in any respiratory infection is simple: is this likely bacterial? A cold or viral acute bronchitis is no place for an antibiotic. Bacterial pneumonia, empyema, and lung abscess absolutely are. The art is in the grey zone between, and the safe instinct is to weigh likelihood honestly rather than 'just in case'.

An unnecessary antibiotic is not harmless. It can cause rashes, diarrhoea, and a dangerous gut infection called C. difficile; it disturbs the body's helpful bacteria, including the lung microbiome; and every needless course nudges bacteria toward resistance. Stewardship means using the right drug, at the right dose, for the shortest effective time — and not using one at all when the cause is viral.

Scoring severity: CURB-65

Even once community-acquired pneumonia is diagnosed, the next decision is how sick the person is and where they should be treated. Clinicians use simple scores to make that call objective. The best known is CURB-65, which awards one point each for confusion, a high blood urea, a fast breathing rate, low blood pressure, and age 65 or over.

CURB-65 score — one point for each item present

  C  Confusion (new disorientation)
  U  Urea > 7 mmol/L (raised blood urea)
  R  Respiratory rate >= 30 breaths/min
  B  Blood pressure: systolic < 90 or diastolic <= 60 mmHg
 65  Age >= 65 years
                                          ----  total /5

Worked example:
  78-year-old, breathing 32/min, BP 130/80, no confusion, urea normal
    age >= 65 ........ 1
    RR >= 30 ......... 1
    others ........... 0
    SCORE = 2

Rough interpretation (clinical judgement still rules):
  0-1  low risk    -> often suitable for home treatment
  2    moderate    -> consider short stay / closer review
  3-5  high risk   -> hospital; consider intensive care at 4-5

CURB-65 turns five quick observations into a severity score that helps decide home versus hospital care. It is a guide, not a verdict.

A low score supports treating a healthy person at home with oral antibiotics and rest; a high score flags someone who needs hospital monitoring, oxygen, or intensive care. Scores never replace judgement — a young person with worrying oxygen levels can be sicker than the number suggests — but they keep decisions consistent and catch dangerous cases early.

Resistance: a shared, slow-motion problem

Antibiotic resistance is not just an individual risk; it is a public one. Every course of antibiotics, anywhere, selects for bacteria that survive it. Over years this has made once-easy infections — including some pneumococcus strains and the resistant bugs of hospital-acquired pneumonia — harder to treat. The drugs we rely on are a shared resource that can be used up.

Do not ask for antibiotics for a cold or viral cough — they cannot help
If prescribed, take them exactly as directed and complete the agreed course
Never use leftover antibiotics or someone else's prescription
Get vaccinated against influenza and pneumococcus to prevent infection in the first place