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Antibiotics
- Medicines that treat communicable diseases
- Their source is microorganisms
- Made from fungi and bacteria
- They kill disease-causing microbes
- Do not harm human body cells
Example 1 — Penicillin
- made from the fungus Penicillium
- controls bacterial infections
- also controls fungal infections
Example 2 — Common antibiotics
- streptomycin and erythromycin
- tetracycline is another
- many are now made synthetically
Important Points
- Antibiotics are ineffective against viruses and protozoa.
- Common antibiotics: penicillin, streptomycin, erythromycin, tetracycline.
- They kill microbes but usually do not damage human cells.
Definition — Antibiotic
An antibiotic means a medicine, obtained from microorganisms, that kills disease-causing microbes without harming human cells.
🔬 Alexander Fleming and Penicillin
Discovered by chance in 1929.
Fleming was growing a culture of disease-causing bacteria when spores of a little green fungus appeared on a plate. He noticed the fungus stopped and killed the bacteria. From this mould, called Penicillium, the antibiotic penicillin was made.
Antibiotic Resistance
- Bacteria can resist antibiotics
- The infection becomes hard to treat
- Fewer antibiotics then work
- Caused by overuse and misuse
- It can spread within a community
Example 1 — Not finishing a course
- patient stops antibiotics early
- resistant bacteria survive
- infection becomes harder to cure
Example 2 — Spread in a community
- resistant bacteria spread by touch
- also through contaminated food
- and in hospitals and travel
Important Points
- Overuse of antibiotics and not completing the full course cause resistance.
- A change in the DNA of bacteria can make them resistant.
- Resistance delays effective treatment and can even cause death.
Definition — Antibiotic Resistance
Antibiotic resistance means when bacteria resist the antibiotics used to treat a disease, making the infection difficult to treat.
🌍 Traditional Medicine and AYUSH
Holistic systems used since ancient times.
Ayurveda, Siddha, Unani and Homeopathy treat many diseases through natural approaches. Ayurveda mostly relies on herbs like Neem, Ginger, Amla, Ashwagandha and Turmeric. The Indian government promotes traditional medicine through AYUSH.
Objective Type Questions Q1(j) - Page 50 Lakhmir Singh
Question
Name the following: The medicine used to treat bacterial infection.
Show answer
Antibiotic
Explanation
- Antibiotics such as penicillin are obtained from microorganisms.
Subjective Type Questions - Short Answer Q4 - Page 51 Lakhmir Singh
Question
It is recommended that we should not take an antibiotic for a viral infection like a cold, a cough, or flu. Can you provide the possible reason for this recommendation? (NCERT Book Question)
Show answer
Antibiotics are ineffective against viruses, so they cannot cure viral infections like cold, cough or flu.
Explanation
- Antibiotics work against bacteria, not viruses.
- Cold, cough and flu are caused by viruses.
- Taking antibiotics needlessly can also lead to antibiotic resistance.
Subjective Type Questions - Long Answer Q5(a) - Page 51 Lakhmir Singh
Question
What are antibiotics? Where do we obtain them?
Show answer
Antibiotics are medicines that kill disease-causing microbes; we obtain them from microorganisms like fungi and bacteria.
Explanation
- They kill microbes but usually do not damage human body cells.
- Common ones are penicillin, streptomycin, erythromycin and tetracycline.
- Penicillin is made from the fungus Penicillium; many are now made synthetically.
Subjective Type Questions - Long Answer Q5(b) - Page 51 Lakhmir Singh
Question
How does antibiotic resistance spread in community?
Show answer
It spreads through contact, contaminated food, animal manure, hospitals, the environment and travel.
Explanation
- Resistant bacteria spread directly by touch, coughs or sneezes, and indirectly through contaminated surfaces.
- By eating food like meat, seafood, eggs and dairy contaminated with resistant bacteria.
- Animal manure used as fertiliser carries them to soil and then to humans through crops.
- They spread through hospitals, healthcare facilities and patients.
- They enter the environment through wastewater, contaminated water and soil, and improper waste disposal.
- People can carry them while travelling from one region to another.
Multiple Choice Questions Q5 - Page 52 Lakhmir Singh
Question
The first antibiotic called penicillin was extracted from:
- (a) a bacterium
- (b) a protozoan
- (c) a fungus
- (d) an alga
Show answer
(c) a fungus
Explanation
- Penicillin was extracted from the fungus (mould) Penicillium.
21st Century Skills Q1 - Page 53 Lakhmir Singh
Question
After consuming a dish of mutton, a person complained of nausea, vomiting, diarrhoea, and pain in the abdomen. (a) What type of disease is he suffering from? (b) What causes this disease?
Show answer
He is suffering from food poisoning, caused by microbes in contaminated food.
Explanation
- (a) It is food poisoning, a communicable disease spread through infected food.
- (b) It is caused by microorganisms such as fungi or bacteria in the contaminated mutton.
21st Century Skills Q2 - Page 53 Lakhmir Singh
Question
Rihan was feeling very sick as he was having high fever. He was also having muscle and joint pain and his glands were swollen. (a) What type of disease is he suffering? Name the causative agent of this disease. (b) Who is the carrier of this disease? (c) Give any two preventive measures for this disease.
Show answer
He is suffering from dengue fever, a viral disease carried by mosquito.
Explanation
- (a) It is dengue fever; the causative agent is a virus. (High fever, muscle and joint pain and swollen glands are dengue symptoms.)
- (b) The carrier (vector) is the mosquito.
- (c) Use mosquito nets and repellents, wear long-sleeved clothes, and remove stagnant water to stop breeding.
