Bacterial Infections: Symptoms, Diagnosis, Treatment, Challenges

Bacteria are single-celled microorganisms in the shape of balls, rods, or spirals. However they’re only visible under a microscope since they’re very small, e.g. the E.coli, bacteria are rod-shaped bacteria, 0.00004 inches by 0.000076 inches long.

Bacteria are everywhere. Most bacteria won’t hurt you, many bacteria are helpful, only 1 percent of bacteria make people sick. Examples of infectious bacteria that make people sick include Streptococcus, Staphylococcus, and E. coli. Bacterial infections are common and affect all age groups.

Bacterial infections can be treated with antibiotics. Antibiotics are generally effective, however the increased usage of antibiotics is causing antibiotic resistance around the world. When you take antibiotics, follow the doctor’s directions carefully.   


Bacteria can infect any area of the body, including the skin, bladder, lungs, intestines, brain, and blood. The symptoms can vary. Some may cause localized symptoms, some may cause generalized symptoms.

Common localized symptoms are:

  • Pain, redness, swelling in skin, throat, eyes, ears, or even internal organs;
  • Chest pain, abdominal pain;
  • Cough, mucus;
  • Diarrhea, vomiting;
  • Diminished organ function.

Generalized symptoms are:

  • Fever
  • Chills
  • Fatigue

Some common bacterial infections include:


Salmonella affects the intestinal tract. Food is the source for most cases, especially the undercooked poultry. Most people have symptoms of diarrhea, fever, and stomach cramps. Symptoms usually begin 6 hours to 6 days after infection and last 4 to 7 days. Salmonella infections lead to 400 deaths each year in the US.

Escherichia coli (E. coli)

E. coli is commonly found in the human intestines. Most E. coli strains are harmless, but some can cause serious food poisoning. Two types of E. coli that cause most diarrhea in the United States are Shiga toxin-producing E. coli (STEC) and enterotoxigenic E. coli (ETEC).

Symptoms of STEC infection include severe stomach cramps, diarrhea (often bloody), and vomiting. Some people may have a fever, which usually is not very high (less than 101˚F/38.5˚C). Although most people get better within 5 to 7 days, some infections can be life-threatening. The outbreaks of E. coli infections in the US are usually a type called STEC O157.

ETEC are the leading cause of traveler’s diarrhea.

Clostridioides difficile (C. diff)

C. diff causes diarrhea and colitis. Most cases of C. diff occur when you’re taking antibiotics or soon after you’ve finished taking antibiotics. C. diff can be deadly.


Tuberculosis is a bacterium that usually attacks the lungs, but the bacteria can attack any part of the body such as the kidney, spine, and brain.

Methicillin-resistant Staphylococcus aureus (MRSA)

MRSA is a cause of staph infection that is difficult to treat because of resistance to some antibiotics. Staph infections—including those caused by MRSA—canspread in hospitals, other healthcare facilities, and in the community.

Streptococcus pneumoniae

Streptococcus pneumoniae can cause many types of illnesses including pneumonia (infection of the lungs), ear infections, sinus infections, meningitis (infection of the covering around the brain and spinal cord), and bacteremia (blood stream infection). Pneumococcus bacteria are spread through coughing, sneezing, and close contact with an infected person.


Diagnosis is done by reviewing medical history, physical exam, and tests. Common tests are:

  • Complete blood count (CBC). The increase of different types of WBCs helps your doctor to identify the infection.
  • C-Reactive Protein (CRP). The CRP level increases when there’s inflammation in your body.
  • Swab. A swab from your throat or ear or other affected area can be sent for an evaluation.
  • Urinalysis. A urine sample is analyzed in the tab to identify bacterial infection in the bladder or kidney.
  • Bacteria culture test. During the culture test, the cells in your sample will be put in a special environment in a lab to encourage cell growth, so as to identify the type of bacteria that you’re infected.


Some bacterial infections can resolve without treatment. Others need antibiotics. Antibiotic selection is based on the type of bacteria involved. Most antibiotics work against more than one type of bacteria, not against all of them.

Antibiotics are available to take orally, topically (on the skin or eye), and intravenously (IV).


The mortality rates due to multidrug-resistant bacterial infections are high. Each year, about 63,000 patients in the United States die from hospital-acquired bacterial infections. The level of antibiotic-resistant infections strongly correlates with the level of antibiotic consumption. The important part is avoiding antibiotics prescription to people who don’t need them, and complying with the drug use regimen.

Related post:

Viral infections: symptoms, diagnosis, treatment, prevention

E. coli infection: symptoms, diagnosis, treatment, prevention

Salmonella infection: symptoms, diagnosis, treatment, prevention

C. difficile infection: symptoms, diagnosis, treatment, prevention

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.