Back to: MICROBIOLOGY 300 LEVEL
Welcome to class!
I’m really glad you’re here today, because we’re going to talk about something every microbiologist and healthcare worker must understand well—mechanisms of bacterial resistance. This topic isn’t just science in theory; it’s happening all around us in Nigeria and across Africa, where many antibiotics are misused, and bacteria are getting stronger and harder to treat. Knowing how bacteria resist antibiotics helps us fight back smarter and protect lives.
Mechanisms Of Bacterial Resistance
What is antibiotic resistance?
Antibiotic resistance happens when bacteria change in a way that makes antibiotics no longer effective against them. It’s like trying to chase away mosquitoes with insecticide only to find that they’ve developed wings that don’t react anymore! In the same way, resistant bacteria keep growing even in the presence of antibiotics.
How do bacteria develop resistance?
Bacteria are clever, and they have developed several survival strategies. Let’s go through them one by one.
1. Enzyme production (Drug destruction)
Some bacteria produce special enzymes that destroy or inactivate antibiotics before the drugs can work.
Example: Beta-lactamases are enzymes that break down penicillins and cephalosporins.
Think of it like pouring water on a fire, but the bacteria have a chemical that turns the water into steam—it no longer quenches the fire!
2. Alteration of target site
The antibiotic may no longer recognise its target because the bacteria have changed the structure it normally binds to.
Example: Mutations in penicillin-binding proteins (PBPs) in Streptococcus pneumoniae reduce the effect of penicillin.
It’s like changing the lock on a door so the original key no longer fits.
3. Efflux pumps (Pumping out the drug)
Some bacteria have built-in pumps that actively remove the antibiotic from their cells before it can do harm.
Example: Tetracycline resistance is often caused by efflux pumps.
Imagine pouring disinfectant into a gutter, but the gutter quickly flushes it away before it can clean anything!
4. Reduced permeability (Preventing drug entry)
Bacteria can change their outer membrane to block the antibiotic from entering the cell.
Example: Gram-negative bacteria often change their porin channels to stop drugs like aminoglycosides from getting in.
It’s like closing the gate before a stranger can enter your compound.
5. Bypass mechanisms
Some bacteria find a different way to carry out essential functions, bypassing the blocked pathway the antibiotic was targeting.
Example: Resistance to sulfonamides occurs when bacteria start using a different enzyme that doesn’t need the blocked pathway.
This is like taking a different road to get home when the main road is blocked.
How do bacteria get resistance genes?
Bacteria can share resistance genes with each other through:
Conjugation (direct transfer via pili)
Transformation (taking up free DNA)
Transduction (through bacteriophages)
So one resistant bacterium in a local clinic in Enugu can pass on its “superpower” to others in no time.
Summary
- Bacteria resist antibiotics by destroying the drug, changing the target site, pumping the drug out, blocking entry, or bypassing the affected pathway.
- Resistance genes can spread between bacteria through conjugation, transformation, and transduction.
- Misuse of antibiotics speeds up this problem, making once-simple infections harder to treat.
Evaluation
- Name two ways bacteria prevent antibiotics from working.
- What enzyme breaks down penicillin in resistant bacteria?
- Explain what an efflux pump does in bacterial resistance.
With each lesson, you’re gaining knowledge that could change how diseases are treated in your community and across the continent. Keep showing up, keep asking questions, and never forget that you’re part of a new generation building a healthier Africa. Afrilearn is proud to walk beside you—see you next class!