Bacterial Infections: Causes, Symptoms and Diagnosis

What is a Bacterial Infection?

A bacterial infection occurs when harmful bacteria invade our bodies and cause illness. Bacteria are tiny microorganisms that can be found all around us, including in the air, soil, water, and even on our skin. While some bacteria are beneficial or harmless, others can make us sick.

When these harmful bacteria enter our bodies, they can multiply and disrupt the normal functioning of our organs and tissues.

This article discusses what you need to know about bacterial infections. It explains the symptoms, causes, and types of bacterial infections. Diagnostic tests and prevention options are also covered.

What are the Symptoms of Bacterial Infection?

The symptoms of a bacterial infection can vary depending on the type of infection and the part of the body that is affected. Here are some common symptoms that may indicate a bacterial infection:

Fever: A bacterial infection can often cause an elevated body temperature, resulting in fever. This is the body’s natural response to fight off the infection.
Pain and inflammation: Infections can lead to pain, redness, swelling, and tenderness at the site of infection. For example, a skin infection may cause a painful, red, and swollen area on the skin.
Coughing and sneezing: Respiratory infections caused by bacteria can produce symptoms such as coughing, sneezing, and congestion. These infections can affect the lungs, throat, or sinuses.
Gastrointestinal symptoms: Bacterial infections in the digestive system may result in symptoms like diarrhea, nausea, vomiting, abdominal pain, and cramping. Food poisoning caused by bacteria is a common example.
Fatigue: Feeling excessively tired or fatigued is a general symptom that can accompany bacterial infections. The body’s immune response to the infection can leave you feeling drained.

What are common bacterial infections?

Bacterial infections can range from mild to severe, and how they affect our bodies depends on the specific bacteria involved. Different types of bacteria tend to target specific areas or parts of our body. Here is a look at common types of bacterial infections.

Food Poisoning

Bacterial food poisoning occurs when food becomes contaminated with harmful bacteria. The most common bacterial causes of food poisoning include:

Salmonella: This bacterium is commonly found in raw or undercooked eggs, poultry, meat, and dairy products. Contamination can occur during the production process or through cross-contamination from raw to cooked foods.
Escherichia coli (E. coli): Certain strains of E. coli, such as E. coli O157:H7, can cause severe food poisoning. Contamination can occur through undercooked ground beef, unpasteurized milk or juice, contaminated water, and contaminated raw fruits and vegetables.
Campylobacter: Contamination of food can occur through raw or undercooked poultry, unpasteurized milk, and contaminated water. Cross-contamination can also occur when raw meat comes into contact with other foods during preparation.

Bacterial Respiratory Infections

Pneumonia: Pneumonia is an infection that inflames the air sacs in one or both lungs. Bacterial pneumonia is often caused by Streptococcus pneumoniae, but other bacteria such as Haemophilus influenzae and Staphylococcus aureus can also be responsible.
Bronchitis: Bacterial bronchitis is an infection that causes inflammation of the bronchial tubes, which carry air to and from the lungs. It is commonly caused by bacteria like Haemophilus influenzae or Streptococcus pneumoniae.
Sinusitis: Sinusitis is an infection that causes inflammation in the sinuses, which are air-filled cavities around the nasal passages. Bacterial sinusitis can be caused by bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis.
Strep throat: Streptococcus pyogenes, commonly known as group A Streptococcus, is the bacteria responsible for strep throat. It causes inflammation and infection in the throat, leading to a sore throat, difficulty swallowing, and swollen tonsils.
Whooping cough (pertussis): Bordetella pertussis is the bacterium that causes whooping cough. It is a highly contagious infection that affects the respiratory tract, causing severe coughing fits, a “whooping” sound during inhalation, and difficulty breathing.
Diphtheria: Corynebacterium diphtheriae is the bacterium that causes diphtheria. It is a serious respiratory infection that produces a thick greyish coating in the throat, leading to difficulty breathing, sore throat, and fever.

Bacterial Skin Infections

Impetigo: Impetigo is a highly contagious skin infection caused by Staphylococcus aureus or Streptococcus pyogenes bacteria. It often affects young children and infants, causing red sores or blisters that rupture, ooze, and form a honey-coloured crust.
Cellulitis: Cellulitis is a bacterial infection that affects the deeper layers of the skin and underlying tissues. It is commonly caused by Streptococcus or Staphylococcus bacteria. Symptoms include redness, swelling, warmth, and pain in the affected area.
Folliculitis: Folliculitis occurs when hair follicles become infected with bacteria, typically Staphylococcus aureus. It leads to small red bumps or pustules around hair follicles, commonly on the face, scalp, or areas that experience friction, such as the buttocks or thighs.
Carbuncles: Carbuncles are clusters of interconnected boils. They are larger and deeper infections that can cause severe pain and a hard, red, swollen mass. Carbuncles are also commonly caused by Staphylococcus aureus bacteria.
Methicillin-resistant Staphylococcus aureus (MRSA) infections: MRSA is a strain of Staphylococcus aureus bacteria that has become resistant to many antibiotics. MRSA can cause various skin infections, including abscesses, boils, cellulitis, or surgical wound infections.

How did bacterial infection spread?

The specific mode of transmission depends on the type of bacteria and the infection involved. Here are some common ways bacterial infections can spread:

Direct contact: Bacterial infections can spread through direct contact with infected individuals. This can occur through physical touch, such as shaking hands, hugging, or kissing. Certain infections, like skin infections or sexually transmitted infections, can spread through intimate contact.
Respiratory droplets: Many bacterial infections can spread through respiratory droplets produced when an infected person coughs, sneezes, or talks. These droplets can contain bacteria, which can be inhaled by nearby individuals, leading to respiratory infections like strep throat, pneumonia, or tuberculosis.
Contaminated food and water: Bacteria can contaminate food and water sources during production, processing, or handling. Consuming contaminated food or water can lead to gastrointestinal infections. Common examples include Salmonella, Campylobacter, or E. coli infections acquired from undercooked or improperly handled food.
Insect bites: Certain bacterial infections can be transmitted through insect bites. For instance, Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted through the bite of infected ticks. Other bacterial infections, such as those caused by Rickettsia or Bartonella bacteria, can be spread by fleas, lice, or mites.

How is the bacterial infection diagnosed?

Various laboratory tests can help identify the presence of bacteria and determine the specific type causing the infection. These tests may include:

Blood tests: A complete blood count (CBC) can indicate the presence of infection by measuring white blood cell count and other markers of inflammation.
Urine tests: Urine samples can be examined for the presence of bacteria and signs of urinary tract infections or other related conditions.
Stool tests: Stool samples can be analyzed to detect bacterial pathogens responsible for gastrointestinal infections.
Wound or tissue cultures: Samples taken from infected wounds, skin lesions, or other affected areas can be cultured to identify the specific bacteria causing the infection.
Respiratory samples: Respiratory secretions, such as sputum or throat swabs, can be tested to identify bacteria responsible for respiratory infections.

Imaging tests: In some cases, imaging tests such as X-rays, computed tomography (CT) scans, or ultrasound may be ordered to assess the extent of infection or detect complications.

How is bacterial infection prevented?

Preventing bacterial infections involves adopting good hygiene practices and taking preventive measures. Here are some essential steps to help prevent bacterial infections:

Hand hygiene: Wash your hands frequently with soap and water for at least 20 seconds, especially before eating, after using the restroom, and after coughing, sneezing, or touching surfaces in public areas. If soap and water are not available, use an alcohol-based hand sanitiser.
Safe food handling: Practice proper food safety measures, such as washing hands before handling food, cooking food thoroughly, avoiding cross-contamination between raw and cooked foods, and refrigerating perishable items promptly.
Safe water practices: Use clean, safe water for drinking, cooking, and brushing your teeth. If you’re unsure about the safety of the water supply, boil water before use or opt for bottled water.
Vaccinations: Stay up to date with recommended vaccinations. Vaccines are available for several bacterial infections, including tetanus, pertussis (whooping cough), pneumococcal infections, and meningococcal infections.
Personal hygiene: Maintain good personal hygiene habits, such as regularly bathing or showering, keeping nails trimmed and clean, and using clean towels and personal care items. Avoid sharing personal items like towels, razors, or toothbrushes.
Proper wound care: Clean and cover cuts, scrapes, or open wounds with sterile dressings to prevent bacterial entry. Seek medical attention for deep or infected wounds.
Avoid close contact with infected individuals: Limit close contact with people who have bacterial infections, especially respiratory infections, until they are no longer contagious.
Environmental cleanliness: Maintain a clean living environment by regularly disinfecting frequently touched surfaces, such as doorknobs, countertops, and shared equipment.
Practice respiratory etiquette: Cover your mouth and nose with a tissue or your elbow when coughing or sneezing. Dispose of used tissues properly and wash hands afterwards.