Bacterial Diseases (AQA GCSE Biology): Revision Note

Bacteria: Basics

• Bacterial pathogens are bacterial cells that can infect plants and animals, causing disease

• Symptoms of a bacterial infection are caused by toxins (poisons) released or secreted by the bacteria, which damage body tissues

Salmonella

• Salmonella bacteria can cause serious food poisoning

• Symptoms are directly caused by the bacteria and the toxins they secrete

Transmission

• Contaminated food that has not been cooked properly, or that has been prepared in unhygienic conditions, is the main cause of salmonella food poisoning

Symptoms

• The bacteria secrete toxins that cause the body to react with:

  • fever

  • abdominal cramps

  • vomiting

  • diarrhoea

• These symptoms are the body trying to remove the infection from the gut

• Symptoms can be more serious in very young or elderly individuals

Control

• Chickens in the UK are vaccinated against salmonella

• Proper hygiene in the kitchen:

  • Preventing raw meat from contaminating cooked meat

  • Cooking all food thoroughly

  • Not washing raw meat as this can spread the bacteria around the kitchen

  • Washing surfaces and hands before and after handling raw meat

Gonorrhoea

• Gonorrhoea is a sexually transmitted disease (STD)

Transmission

• Gonorrhoea is spread by unprotected sexual contact

Symptoms

• Symptoms include:

  • thick, yellow or green discharge from the vagina or penis

  • pain when urinating

Control

• Barrier methods of contraception, such as condoms, can prevent the spread of gonorrhoea

• Can be treated with antibiotics, but now many strains are becoming resistant to the most used antibiotic penicillin

• During an outbreak, tracing of all sexual partners is essential so that all individuals can be tested and treated