Most Common Bacterial Infections Of Humans

Respiratory Infections A wide range of bacteria are infectious, leading to a mild or severe life threatening conditions of bacterial meningitis that need immediate intervention.

Bacterial infections have been a leading cause of deaths in elderly and children in the US. Moreover, people suffering from chronic diseases or undergoing long term hospitalization, are at much higher risk of bacterial infections.

With development of a powerful tool of antibiotics, which has been there since 1940s,infected people can still be safeguarded from severe affects of bacterial infections.

However, with widespread and sometimes, inappropriate usage of these antibiotics, bacterial strains have evolved to be more antibiotic resistant. These newer, resistant bacteria pose an alarming threat to health and welfare of all of us, and medical science has been left with more new challenges to face.

Under healthy lifestyle, we all are protected from infections due to our most efficient immune system. Hence, we can protect ourselves against bacterial infections by ensuring that our immune system remains healthy all throughout.

Most Common Bacterial Infections

Respiratory Infections

The most commonly occurring infections both in children and adults are upper respiratory tract infections. Bacteria contribute 25% to upper respiratory infections, with 95% contributed by group A streptococci, causing strep throat infections in US.

Strep throat infections are more common in children and adolescents between three to eighteen years of age. Haemophilus influenza is another bacterium commonly causing epiglottitis (throat’s internal swelling), meningitis (infection of covering sheath of spinal cord and brain) and pneumonia (infection of lungs).

Otitis Media

Ear infections of the middle ear, referred as otitis media are the most frequent occurring illnesses in babies and toddlers, where Eustachian tube (tube connecting ears to throat) is not completely developed.

OME or Otitis Media

Such ear infections majorily occur with bouts of sore throats or colds, when infectious microbes get higher probability to thrive on the accumulated fluid within the ears. S. pneumonia and H. influenza are the major bacteria causing these infections.

Lower Respiratory Tract Infections

Prevalent lower respiratory tract infections include nosocomial infections (Hospital associated infections), acute or chronic bronchitis and pneumonia infections. Streptococcus pneumonia remains the common cause of community acquired pneumonia and lung infections. These infections have equal chances of occurrence in both immunocompromised and healthy individuals.

Tuberculosis (TB)

Most of the population is affected with Mycobacterium tuberculosis, but only very few out of these actually progress into a clinically evident disease. TB infection will only progress depending upon nutritional status and immunity of an individual.


Those with healthy immune system never develop infection into the disease stage. TB occurs more profoundly in poor populations, people in age group of teenage to young adulthood, those beyond 60, HIV infected individuals or individuals who have been incarcerated beyond 6 months. It basically spreads rapidly in crowded places with high exposure of tuberculosis bacteria.

Gastrointestinal Infections


One of the leading causes of mortality and morbidity worldwide is the infectious diarrhea. Most of the diarrhea is of viral origin, but many are caused by bacteria too. Important bacterial pathogens causing diarrhea include species of Salmonella, Campylobacter, E. coli and Shigella. Campylobacter jejuni is the commonest cause of bacterial diarrhea in US, with Salmonella being the second frequent cause of diarrhea.

A bloody or watery diarrhea with fever, abdominal pain and malaise symptoms, is caused by Shigella species. E. coli O157: H7 strain is known to cause a severe form of diarrhea, known as haemolytic uremic syndrome. It also leads to prominent food poisoning outbreaks that get transmitted through apple cider, hamburger meat, vegetables and fruits.


The major cause of peptic ulcers and gastritis in children and adults is Helicobacter pylori. Acute infection leads to weight loss, abdominal pain, nausea and vomiting. H. pylori affect nutrient absorption by altering the balance of folic acid, vitamin B12, alpha tocophenol, iron, beta carotene and vitamin C.

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Skin Infections

Many of the skin infections are self-limiting and get fine with time, but a few others do require medical attention.

Bacterial Skin

Boils, cellulitis, impetigo, carbuncles and burns complications are major skin infections caused by Pseudomonas aeruginosa, Staphylococcus aureus and group A streptococci. Impetigo is mainly caused by group A streptococci, which may shapen into drastic kidney inflammation or even a kidney failure.

Bacterial Vaginosis (BV)

When the normal microbial flora colonizing in the women vagina gets disrupted with over growth of bacteria, it leads to bacterial vaginosis. BV is the most common cause of vaginal discharge during reproductive years of women.

Few factors like vaginal douches, multiple partners and usage of IUD increases the risk of bacterial vaginosis. BV sufferers produce a specific fish like vaginal odour with greyish or white vaginal discharge, which may be foamy or watery, giving a clear indication of vaginal infection.

Hospital Acquired Infections

Health care or hospital acquired infections are enormously increasing threat to health and safety of patients, since, hospital stay leads to certain nosocomial infections like ventilator associated pneumonia (VAP), bloodstream infection, urinary tract infection (UTI) and surgical site infection (SSI).

MRSA (methicillin resistant staphylococcus aureus) is the common cause of hospital based infections that are more difficult to treat, as these microbes are resistant to commonly used methicillin antibiotic.

Hospital acquired infections

There exist around ten times more cells of bacteria in the human flora then other cells of the human body, with a large proportion of these residing in the gut flora and the skin.

A certain number of resident bacteria are beneficial to the human body and the protective immune system battles the rest of the bacteria, rendering them harmless for the body. Only less than one percent of bacteria will cause illness to the human and the way they do so, is by infecting our healthy cells or tissues.

Proper Antibiotic Usage To Combat Bacterial Infections

For every bacterial infection, specific antibodies are given and that is administered by the doctor based on symptoms and after proper diagnosis of a particular bacterial infection.

One needs to rake proper, routine, timely and complete course of antibiotics to get recovered on time. Moreover, it is significantly important to lower down the problem of antibiotic resistance that majorily happens due to improper administration of antibiotics.

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