Is Pus a Sign of Infection? What Causes It?

Pus is a thick fluid that builds up when an injury becomes infected. However, pus is not the sole indicator of infection.

The word "pus" evokes unpleasant images and is associated with injuries and infection, commonly something people dislike thinking about.

Pus is a thick fluid that forms when an injury gets infected. It can come in different colors such as white, yellow, green, or brown. It may also have a foul odor, but not always. Sometimes, it may not have any scent at all.

Despite its negative connotation, pus is actually a natural part of the healing process for wounds. It serves as both a sign of infection and an indication that the body is actively fighting the infection to heal the injury.

Once an infection occurs, the immune system initiates a response to combat it. The area becomes infiltrated with white blood cells that aim to destroy the bacteria. Over time, these white blood cells and damaged tissue accumulate in the affected area, resulting in the formation of pus.

To learn more about pus, its causes, and how to treat an infected wound, continue reading.

Signs of Pus and Wound Infection

Pus is not the only symptom of an infection. In addition to the presence of pus, infected areas typically appear red, swollen, and warm to the touch. Pain in the affected area is also common. In severe cases, symptoms like fever, aches, or chills may arise as the body fights off the infection.

Causes of Pus and Wound Infection

Pus often develops in an abscess, which forms when there is a breakdown in the body’s tissue. Bacteria can enter wounds when the outer layers of the skin are compromised, leading to an infection. Abscesses can develop on various parts of the body, including the skin, mucus membranes, or internal organs.

Skin abscesses are particularly common and can form from something as minor as a small cut or an ingrown hair. These small wounds may become infected and produce visible pus, similar to a pimple. Eventually, the abscess will burst and drain, aiding the healing process.

Infections can also occur deeper within the body, where pus may collect in hidden abscesses. These infections often manifest as swollen, painful areas, accompanied by redness. Without proper treatment, the infection can worsen or spread.

Surgical wounds are at risk of infection as well. If you notice increasing pain around the incision, swelling, redness, or pus seeping through bandages or drainage tubes, it is essential to seek medical attention.

QUESTION

When to See a Doctor for Pus and Wound Infection

For small infections measuring less than half an inch in diameter, you can typically manage them at home using warm compresses. However, if the sore is larger than half an inch or if a small wound expands or intensifies in pain, or you experience a fever, it is advisable to consult a doctor. Additionally, seek medical attention if red streaks develop around the infected area, as this may indicate the infection is spreading.

Infections in the groin area or near the anus also necessitate medical attention.

Regarding surgical site infections, contact the doctor who performed the operation. For dental abscesses, consult a dentist.

Diagnosis of Pus and Wound Infection

Upon visiting the doctor, be prepared to provide information about the injury and the duration of the infection. The doctor will examine the wound and its surrounding area to assess the extent of the infection.

In some cases, the doctor may collect pus samples from the infection to test them for bacteria or fungus. The test results will guide the appropriate prescription of medication to eradicate the infection.

Treatments for Pus and Wound Infection

Pus-filled abscesses often require drainage to facilitate complete healing. The method of drainage will depend on the abscess’s location on the body and may involve an in-office procedure or a more extensive intervention.

The doctor will administer a local anesthetic to numb the area before draining the pus. Drainage can be achieved by either using a needle or making an incision and allowing the pus to escape through the opening.

Dental abscesses can generally be treated in the dental office. The dentist will numb the area and remove the infected material. In some cases, a root canal may be necessary to address the underlying issue.

Following pus removal, the doctor may prescribe antibiotics to prevent a recurrence. It is vital to adhere to the prescribed medication regimen and carefully follow the doctor’s wound care instructions at home.

Bacterial Infection Examples

Bacteria, despite being invisible to the naked eye, are microscopic microbes that can be observed under a microscope.

There are two types of bacteria: beneficial (or good) bacteria and harmful (or bad) bacteria.

Beneficial bacteria reside within the body and contribute to digestion, vitamin production, and immune system support. Conversely, harmful bacteria exist in the environment and can cause diseases when they enter the body, particularly when the immune system is weakened. These harmful bacteria are also known as infectious bacteria.

The severity of a bacterial infection depends on the specific bacteria involved. Bacteria most commonly infect the gut, skin, and respiratory system (including the lungs, urinary tract, and vagina). While there are numerous bacterial infections, some common examples include:

• Bacterial infections of the digestive tract: Food poisoning, commonly caused by non-typhoidal Salmonella bacteria found in the intestinal tracts of humans and animals, often occurs after consuming undercooked poultry. This infection leads to symptoms such as bloating, diarrhea, and vomiting. Gastrointestinal (GI) infections can also be caused by Escherichia coli (E. coli), where certain strains cause stomach and intestinal infections. Helicobacter pylori (H. pylori) infection of the stomach and intestine can result in chronic gastritis and gastric ulcers, characterized by abdominal pain and weight loss.
• Bacterial infections of the lung: Tuberculosis is a highly communicable disease caused by Mycobacterium tuberculosis (M. tuberculosis), which can cause chronic cough, fever, coughing blood, and significant weight loss. Bacterial pneumonia, caused by different bacteria such as Streptococcus pneumoniae, Klebsiella pneumoniae, and Pseudomonas aeruginosa, leads to symptoms including high-grade fever, severe coughing, and shortness of breath.
• Bacterial infections of the vagina and urinary tract: Bacterial vaginosis is a vaginal infection that causes itchiness, greyish vaginal discharge, and painful urination. Urinary tract infections (UTIs), more common in women than men, can include cystitis (bladder infection) and urethritis (urethral infection). Symptoms of UTIs typically involve burning or painful urination, frequent urination, and sometimes abdominal pain. Gonorrhea, an infection caused by Neisseria gonorrhoeae, affects both men and women and commonly affects the urethra, rectum, or throat.
• Bacterial infections of the skin: Common bacterial skin infections include cellulitis (swollen, red, and painful skin), erysipelas (similar to cellulitis but affects the upper layer of skin), impetigo (red sores that burst and crust over, primarily around the nose, mouth, hands, and feet), folliculitis (small bumps around hair follicles), furuncles (boils), and carbuncles (clusters of boils). Vibriosis (non-cholera) is a bacterial infection caused by Vibrio species found in warm seawater, such as Vibrio vulnificus, Vibrio parahaemolyticus, and Vibrio alginolyticus. This infection is transmitted through the consumption of raw or undercooked shellfish.

References:

Merriam Webster: "Pus."

National Health Service UK: "Abscess."

National Health Service UK: "Dental Abscess."

The Ohio State University Wexner Medical Center: "Six signs your wound isn’t healing right."

U.S. National Library of Medicine: "Surgical wound infection – treatment."

Medscape: "Infectious Diseases."

CDC: "Diseases and Organisms in Healthcare Settings."