Bacteria in Action

Bacteria are everywhere - there's no escaping them. They are present, by the millions, in the air we breathe, the food we eat and on most surfaces we touch everyday.

A bacterial infection, in its most basic terms, means that foreign bacteria have gained entry into the body and are causing damage to organs, both directly through chemical substances that they synthesize and indirectly through the organism's inflammatory response. Disease doesn't happen just because of the mere presence of bacteria. If a person becomes ill, it is because the bacteria have managed to escape the body's natural defences and cause local and/or general damage.

Below are tables outlining many common bacteria and the diseases they cause, their symptoms and where they are found in the environment.

Bacteria	Salmonella typhimurium
Disease	Salmonellosis (food poisoning)
Symptoms	Stomach cramps, nausea, vomiting, diarrhea, fever
Source/mode of infection	Raw and undercooked meats (especially poultry), raw milk, eggs, sprouts Fruits, vegetables exposed to contaminated soil or a surface infected with the bacteria (eg. countertop, utensils or unwashed hands)

Bacteria	Salmonella typhi
Disease	Typhoid fever
Symptoms	Sustained fever, weakness, stomach pains, headache, loss of appetite, rash of flat, rose-coloured spots
Source/mode of infection	Most likely contracted while traveling: Avoid raw vegetables, fruits that cannot be peeled Unbottled water Ice cubes in drinks

Bacteria	Clostridium botulinum
Disease	Botulism (food poisoning)
Symptoms	Affects the nervous system - muscle paralysis, difficulty breathing, dry mouth, double vision, nausea, vomiting, abdominal cramps, sore throat, dizziness, constipation, weakness, difficulty focusing on a near point, diarrhea, difficulty swallowing
Source/mode of infection	Food eaten from damaged containers or containers with leaking or bulging lids Food left at room temperature for more than two hours Undercooked food (botulism toxin is destroyed by boiling for 10 minutes)

Bacteria	Escherichia coli (E. coli)
Disease	Gastroenteritis
Symptoms	Abdominal cramps, bloody diarrhea, nausea, vomiting, fever, kidney failure may be caused by more dangerous strains.
Source/mode of infection	Undercooked or raw meat Contaminated well water Unpasteurized milk, apple juice and apple cider Alfalfa sprouts, lettuce Unchlorinated swimming pool water infected with human fecal matter

Bacteria	Group A Streptococcus
Disease	Streptococcal pharyngitis (strep throat)
Symptoms	Red and painful sore throat, white patches on tonsils, swollen lymph nodes in neck, fever, headache
Source/mode of infection	Person-to-person by direct contact with saliva or nasal discharge (very common in crowded environments - dormitories, schools, institutions) Occasionally through contaminated milk products

Bacteria	Streptococcus pneumoniae ("Pneumococcus")
Disease	Bacterial pneumonia
Symptoms	Fever, chills, cough, difficulty breathing, chest pain, abdominal pain, loss of appetite
Source/mode of infection	Often begins after an upper respiratory tract infection (infection of the nose and throat) within 2-3 days of a cold or sore throat

Bacteria	Neisseria meningitidis ("Meningococcus")
Disease	Meningitis
Symptoms	Fever, vomiting, diarrhea, severe headache, neck stiffness, joint or muscle pains, stomach cramps, sensitivity to bright light, drowsiness, confusion or disorientation, possibly rash
Source/mode of infection	Person-to-person by direct contact with saliva or nasal discharge (occasionally seen in crowded environments - dormitories, schools, institutions) Drinking water contaminated by sewage, waste water treatment facilities, discharges from industrial processes, farmland, homes and yards

Bacteria	Mycobacterium tuberculosis
Disease	Tuberculosis
Symptoms	Fever, cough, weight loss, night sweats; chronic lung infection
Source/mode of infection	Inhalation of airborne organisms (coughing, sneezing, speaking) Procedures, such as cough induction or bronchoscopy associated with an increased generation of infectious particles from people with pulmonary TB,

Bacteria	Staphylococcus aureus
Disease	Mild to severe skin and wound infections; septicemia
Symptoms	Pus-containing abscesses or styes characterized by localized inflammation, redness and warmth at infection site, swelling, and sometimes, necrosis of tissue; septicemia may occur if bacteria are allowed to invade the blood stream, possibly resulting in kidney, liver heart, muscle infection
Source/mode of infection	Improper disinfection of open cuts; rare complication of surgical wounds

Bacteria in Action | Bacterial vs. Viral Infections | Good and Not-So-Good Bacteria | The Evolution of Bacterial Resistance