Bacterial Infection: Types, Treatment and Bacteria vs. Virus

The proliferation of a harmful strain of bacteria on or inside the body is known as bacterial infection

Updated: June 16, 2022

Bacteria are microscopic, single cell organisms that live almost everywhere including every climate and location on earth. Some are airborne while others live in water or soil. Bacteria live on and inside plants, animals, and people. Bacteria actually perform many vital functions for organisms and in the environment. Bacteria in the soil are essential for plants to grow. The presence of good bacteria in human gastrointestinal tract helps in digestion and produce vitamins. They also help with immunity, fighting against bad bacteria and other harmful pathogens. 

However, few strains of bacteria are capable of making people sick. Bacterial skin infections are usually caused by gram-positive strains of Staphylococcus and Streptococcus or other organisms.
The proliferation of a harmful strain of bacteria on or inside the body is known as bacterial infection. All parts of the body can get infected by a bacteria . Pneumonia, meningitis, and food poisoning are some of the examples that may be caused by harmful bacteria. 
Bacteria can be rod-shaped (bacilli), spherical (cocci), or helical (spirilla). Bacteria may also be classified as gram-positive or gram-negative. Gram-positive bacteria have a thick cell wall while gram-negative bacteria does not have that. Bacterial strains can be identified by gram staining, bacterial culture with antibiotic sensitivity determination, and other tests which can help determine the appropriate course of treatment. The symptoms of a bacterial or viral infection depend on the area of the body that is affected.

Types of Bacterial infection:

Bacterial infection can be of several type. These include:

Bacterial Skin Infections:

Bacterial skin infections are usually caused by gram-positive strains of Staphylococcus and Streptococcus or other organisms. Common bacterial skin infections include:


It causes a painful, red infection that is usually warm to the touch. Cellulitis occurs most often on the legs, but it can appear anywhere on the body. 


It is an infection of the hair follicles that causes red, swollen bumps that look like pimples. Improperly treated pools or hot tubs can harbor bacteria that cause folliculitis.


It causes oozing sores, usually in preschool aged children. The bullous form of impetigo causes large blisters while the non-bullous form has a yellow, crusted appearance. 


These are deep skin infections that start in hair follicles. Boils are firm, red, tender bumps that progress until pus accumulates underneath the skin. Bacterial skin infections often begin as small, red bumps that slowly increase in size. These can be treated with oral or topical antibiotics depending on the strain causing the infection.

Food borne Bacterial Infections:

One of the main cause of food borne illness is bacterial infections. Nausea, vomiting, diarrhea, fever, chills, and abdominal pain are most common symptoms of food poisoning. Raw meat, fish, eggs, poultry, and unpasteurized dairy are the source of harmful bacteria that can cause illness. Unsanitary food preparation and handling can also encourage bacterial growth. Bacteria that cause food poisoning include:

Campylobacter jejuni (C. jejuni):

It is a diarrheal illness that often accompanied by cramps and fever.

Clostridium botulinum (C. botulinum):

This is a potentially life-threatening bacterium that produces powerful neurotoxins.

Escherichia coli (E. coli) O157:H7 :

It is a diarrheal illness that may be accompanied by nausea, vomiting, fever, and abdominal cramps. More severe cases can lead to bloody diarrhea, dehydration, or even kidney failure. People with weakened immune systems, pregnant women, young children, and older adults are at increased risk for developing these complications. Most intestinal infections are caused by contaminated food or water. Proper food preparation and good hygiene can greatly decrease your chances of developing an intestinal infection.

Listeria monocytogenes (L. monocytogenes):

This bacteria can cause fever, muscle aches, and diarrhea. Pregnant women, elderly individuals, infants, and those with weakened immune systems are at a higher risk for acquiring this infection.


The most common way to get salmonella is by eating meat or eggs or drinking milk that is contaminated. But you can also get it by eating fruits or vegetables that have been in contact with manure from animals that have it.This can cause fever, diarrhea, and abdominal cramps. Symptoms typically last between 4 and 7 days. 
If the salmonella infection gets into your blood, it can infect your body's tissues, such as the tissues around your brain and spinal cord, the lining of your heart or heart valves, your bones or bone marrow and the lining of blood vessels. These infections can lead to serious diseases.


It causes diarrhea when ingested, but it can also cause severe skin infections when it comes in contact with an open wound. Vibrios typically cause disease in people who eat contaminated seafood. V. parahaemolyticus typically causes non-bloody diarrhea. 
In persons with liver disease, cancer, or another immune-compromising condition, V. vulnificus typically infects the bloodstream, causing a  life-threatening illness. About half of V. vulnificus bloodstream infections are fatal, and death can occur within two days. In addition to transmission by raw shellfish, V. vulnificus can enter the body via a wound that is exposed to warm seawater.

Sexually Transmitted Bacterial Infections:

Many sexually transmitted diseases (STDs) are caused by harmful bacteria. Sometimes, these infections does not show any sign and symptoms but can still cause serious damage to the reproductive system. Common STDs caused by bacterial infections include:


The infection is caused by an organism called Chlamydia trachomatis both in men and women. Chlamydia increases the risk of pelvic inflammatory disease (PID) in women. 


It is also known as clap and the drip. The infection is caused by Neisseria gonorrhoeae both in men and women. Gonorrhea also increases the risk of pelvic inflammatory disease (PID) in women. 


It can affect both men and women and is caused by the bacteria Treponema pallidum. Left untreated, syphilis can be very dangerous and can even fatal. 

Bacterial vaginosis:

This causes an overgrowth of pathogenic bacteria in the vagina.  

Other Bacterial Infections:

Depending on which area of the body is affected by harmful bacteria, other types of bacterial infections include:

Bacterial meningitis:

It is a severe infection of the meninges, the lining of the brain. The swelling from meningitis typically triggers symptoms such as headache, fever and a stiff neck.
When bacteria enter the bloodstream and travel to the brain and spinal cord, it causes acute bacterial meningitis. But it can also occur when bacteria directly invade the meninges. This may be caused by an ear or sinus infection, a skull fracture, or, rarely, after some surgeries.

Otitis media:

An infection or inflammation of the middle ear is known as otitis media. Ear infections can be caused by  bacteria as well as viruse, which commonly occur in babies and small children. 
The eustachian tube is the tube that runs from the middle of the ear to the back of the throat. When the eustachian tube becomes swollen or blocked and traps fluid in the middle ear and the trapped fluid become infected, an acute otitis media occurs. As the eustachian tube is shorter and more horizontal in young children than in older children and adults, it is more likely to become infected in young child. The eustachian tube can become swollen or blocked because of allergies, a cold, flu, sinus infection or infected or enlarged adenoids.

Urinary tract infection (UTI):

This is a bacterial infection of the bladder, urethra, kidneys, or ureters. Some of the common symptoms of UTI include burning with urination, increased frequency of urination without passing much urine, increased urgency of urination, bloody urine and cloudy urine.
Pelvic pain in women and rectal pain in men are also some of the symptoms of lower tract UTI. Upper tract UTIs affect the kidneys which can be potentially life threatening if bacteria move from the infected kidney into the blood. This condition, called urosepsis, can cause dangerously low blood pressure, shock, and death.
Symptoms of an upper tract UTI include pain and tenderness in the upper back and sides, fever with chills, nausea and vomiting.

Respiratory tract infections:

The infection include sore throat, bronchitis, sinusitis, and pneumonia. Both bacteria and viruses may be responsible for respiratory tract infections. A lower respiratory tract infection by bacteria can cause Tuberculosis. Cough with mucus, sneezing, stuffy or runny nose, sore throat, headache, muscle aches, breathlessness, tight chest or wheezing and fever are some of the symptoms of RTI.


Treatment is based on how often the bacteria is found in the local area and whether or not it has been found to be resistant to commonly used antibiotics. Skin infections caused by less common bacteria may develop in people while hospitalized or living in a nursing home, while gardening, or while swimming in a pond, lake, or ocean.
Antibiotics are medications that fight bacterial infections. The processes necessary for bacterial cell growth and proliferation can be disrupted by antibiotic. It is important to take antibiotics exactly as prescribed, as a bacterial infection can get worse by not following the prescribed instruction. Antibiotics are not helpful in  treating viruses. However, they are sometimes prescribed in viral illnesses to help prevent a secondary bacterial infection.
Secondary infections occur in people with a weakened or compromised immune system due to an existing illness. Because of the risk of developing an allergy to the antibiotic, it is recommended not to use antibiotic ointments on uninfected minor wounds. An antibiotic ointment is used only if an infection develops. Larger areas require oral antibiotics or injection. Abscesses or pus filled pockets should be cut open by the doctor and allowed to drain, and any dead tissue must be surgically removed.

Antibiotic Resistance:

Overuse and misuse of antibiotics can led to antibiotic resistance which means bacteria are no longer sensitive to a medication that are used to treat an infection.
Antibiotic-resistant bacterial infections are potentially very dangerous and could be fatal. Clostridium difficile or C. difficile infections that occur because of antibiotic suppression of other bacteria can lead to death in many cases. This is due to proliferation of C.difficile as a result of antibiotic resistance.

Good Bacteria and Probiotics:

Good bacteria that are benifical lives in the human gastrointestinal (GI) tract and play an important role in digestion and immunity. After completing a course of antibiotics, eating yogurt can reproduce the helpful bacteria in the GI tract that were wiped out by the effect of antibiotics. The duration of infectious diarrhea can be shorten by using probiotics. Probiotics can help reduce gas, bloating, and abdominal pain associated with irritable bowel syndrome (IBS).  

Prevention of Bacterial infections:

Keeping the skin undamaged and clean can be a preventive step towards bacterial infections. The injury should be washed with soap and water and covered with a sterile bandage when the skin is cut or scraped. Petrolatum may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. 

Bacteria vs. Virus:

Viruses and bacteria are two types of potentially disease causing particles. Viruses are much smaller than bacteria and can ntt reproduce without the assistance of a host. Viruses will depend on the organ that is affected by them for re-population. Bacteria on the other hand are capable of reproducing on their own. 
Sometimes the symptoms of viral and bacterial illnesses are similar. The underlying cause of an illness can be determined based on the symptoms of a patient and other factors. It is always advisable to clarify whether an illness is due to a virus, bacteria, or other infectious agent or disease process for making a proper treatment decision. Lab tests may help in this regards.

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