Bacteria are found on each and every surface around us, surviving in the most inhabitable and hostile environment in the world. They are made up of just a single cell and are able to pro-generate through division of cell. They have a nucleus, that contains genes, genes which are made up of DNA, and DNA replication helps in production of new bacterial cells. Bacteria are found in and on the human body. There are many beneficial bacteria to humans that help us in many ways. But, there are certain harmful bacteria called pathogens, that cause bacterial infections or diseases.
Bacteria affect people who have low immunity like the elderly or infants. Malnutrition or deficiency of vitamins and nutrients may also lead to these infections. Bacteria can easily spread due to unhygienic practices and touching unclean objects and surfaces. Sexually transmitted diseases like chlamydia, gonorrhea are bacterial infections transmitted by contact with body fluids during sexual activities. Bacterial vaginosis is another infection that causes discharge with embarrassing fishy odor in women. Food borne diseases like diarrhea, dysentery, food poisoning are diseases caused by bacteria like Clostridium botulinum, Brucella melitensis, Salmonella typhi, etc. These infections are contagious enough to affect many people who eat the same food. One can not forget the story of a 'Typhoid Mary', who was thought to be a carrier of Salmonella typhi. She has been known to infect many people and even caused death of many by spreading bacterial infections.
A streptococcal throat infection is very contagious and can spread very quickly. A bacterial throat infection is known to be very contagious during the first 24 hours of infection. Bacterial pink eye infection is also very contagious. It can spread by just merely touching or using an object that has been used by an infected person with pink eye. Thus, children suffering from pink eye are asked to remain at home and resume school later, to reduce the spread of infection.
Other bacterial infection spread through a biological vector. These biological vectors are nothing but bites of insects like fleas, ticks, or contact with bird droppings, infected birds, infected cattle, horses, rodents and even humans. Bacterial infections like anthrax caused by Bacillus anthracis, Lyme disease by Borrelia burgdorferi, Meningococcal meningitis due to Neisseria meningitis, syphilis due to Treponema pallidum are highly contagious and known to cause epidemics around the world. Tuberculosis caused by Mycobacterium tuberculosis, is still a major bacterial infection
Food and water contaminated by fecal matter of humans and animals can be another mode of spreading bacterial infections. Legionnaire's disease caused by Legionella pneumophila, Parathyphoid by Salmonella paratyphi, etc. are also known to be very infectious diseases.
Common Infection Causing Bacteria
Bacteria who are otherwise beneficial and peaceful inhabitants of the human body, tend to grow and develop these infections, simply because they may be present at the wrong place in the body or their genetic make up is designed to invade the host. There are thousands of bacteria, but only a few cause bacterial infections in humans.
Staph is a harmless bacteria and is the most common bacteria found in the human body. There are some species of Staphylococci that cause bacterial infections like methicillin resistant Staphylococci aureus. This is the most common bacteria that causes serious skin diseases. There are over 40 species of Staphylococcus genus. They are generally harmless and live on the skin surface as well as mucous membranes of animals as well as humans. They are Gram-positive cocci that appear in clusters after staining. They are facultative anaerobes and can grow in presence of bile salts. These organisms are catalase-positive. These features help microbiologists differentiate these organisms from other aerobic as well as facultative anaerobes.
Another common bacteria found in and on the human body. It causes many bacterial infections of the respiratory tract like pneumonia and strep throat. Streptococcus are spherical Gram-positive bacteria. They grow in chains or pairs. Most of the organisms in this genus are oxidase- as well as catalase-negative and some are facultative anaerobes. These bacteria are responsible for many diseases in humans like meningitis, pneumonia as well as the dreaded necrotizing fasciitis. However, some species are beneficial and used as an ingredient for making 'Swiss' cheese. Their characteristic feature of identification during plating is hemolysis of iron from the blood agar.
This bacteria was formerly known as Bacillus influenzae or Pfeiffer's bacillus. Haemophilus influenzae is a Gram-negative rod-shaped bacteria. This organism is generally an aerobic bacteria, but can survive as a facultative anaerobe, if need be. Haemophilus influenzae, is an opportunistic pathogen that can survive within the host without ever leading to an infection. However, when it gets the right opportunity, like weak immune system or viral infection in body, it will lead to an infection or disease. It can cause bacterial meningitis, pneumonia, cellulitis, osteomyelitis, infectious arthritis, etc. Unencapsulated H. Influenzae can cause ear infections, conjunctivitis, and sinusitis in children.
The most common inhabitant of the digestive system can cause severe diarrhea. E.coli can also cause food poisoning. It is a Gram-negative, rod-shaped bacterium that inhabits the lower intestines of all warm-blooded animals, including humans. E.coli strains are generally harmless and live peacefully within the body. However, certain strains can lead to food poisoning. The harmless bacteria help in production of vitamin K2 in the gut of the host. These organisms are facultative anaerobes and do not sporulate. The virulent strains cause gastroenteritis, meningitis, urinary tract infections, septicemia and other diseases in humans.
This is the most common bacteria that causes stomach ulcers. Helicobacter pylori is an Gram-negative, microaerophillic bacterium. It is present in the stomach of more than 50% of the population around the world. It has a helix shape that gives rise to its generic name. This bacteria causes gastritis, gastric ulcers and is linked to development of stomach cancer as well as duodenal ulcers. However, in about 80% of the carriers it remains asymptomatic.
This a food borne pathogenic bacteria that causes diarrhea and food poisoning. Salmonella is a rod-shaped, non-spore-forming, Gram-negative bacteria. It is motile and uses flagella for movement. These bacteria are chemoorganotrophs, that is, they use chemical reactions to get energy from organic sources. This bacteria is found in both cold as well as warm-blooded animals, that includes humans. Salmonella are known to cause typhoid fever, paratyphoid fever as well as many other food borne illnesses.
Bacterial infections are contagious and spread like wild-fire. You can yourself determine if your infection seems infectious or not. Stay at home and take plenty of rest to get healthy. Eat a healthy diet and maintain a strong immune system. Most bacteria are opportunistic pathogens, thus, do not give them an opportunity to invade your body.