Antibiotic Resistance in a Hospital Ward
A hospital ward reports rising infections with a bacterium resistant to several antibiotics. Records show that over two years the proportion of resistant isolates rose from 15 percent to 60 percent. During the same period, broad-spectrum antibiotics were used routinely for patients with mild fevers before culture results were available, and handwashing compliance audits scored 55 percent. The ward has 30 beds and often admits patients transferred from other facilities.
1. Explain how the ward conditions could have produced the rise in resistance, using the principles of natural selection.
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Bacterial populations contain variation, including some cells with genes or mutations conferring resistance. Routine broad-spectrum use kills susceptible cells and leaves resistant ones to survive and reproduce, so the proportion of resistant bacteria rises - selection under antibiotic pressure. Resistance genes can also spread between bacteria by horizontal gene transfer (e.g. plasmids), accelerating the process. Crowding, transfers between facilities and poor hand hygiene increase transmission of resistant strains between patients. The rise from 15 to 60 percent is the expected outcome of these combined pressures, not evidence that the antibiotic 'created' resistance in each patient.
2. Propose interventions and rank them by expected impact, justifying your ranking.
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Highest impact: improve hand hygiene and infection control, because it blocks transmission of already-resistant strains between patients. Next: restrict and rationalise antibiotic use - culture first where possible, narrow-spectrum agents, stop unnecessary courses - which reduces selection pressure. Also: isolate or cohort colonised patients, screen transfers, and educate staff and patients. Hand hygiene ranks first because resistant organisms are already present and spreading; reducing selection helps but acts more slowly. A combination is needed, but the ranking should reflect that transmission control gives the fastest reduction.
3. A doctor says 'if we simply use stronger antibiotics, resistance will stop'. Evaluate this reasoning.
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The reasoning is flawed. Using stronger or newer antibiotics increases selection pressure and tends to select for resistance to those agents too; resistance has followed each new class introduced. It also does not address transmission, so resistant strains continue to spread. New drugs are valuable but must be used prudently and combined with infection control. The claim confuses treating individual patients with controlling resistance in a population.