Pseudomonas: How Serious Is Bacterial Infection?

Pseudomonas is a genus of gram-negative bacteria. It belongs to the family Pseudomonadaceae and is in the class Gammaproteobacteria. Not all strains of this type of bacteria cause infection, but roughly 25 species, including Pseudomonas aeruginosa (P. aeruginosa), Pseudomonas fluorescens (P. fluorescens), and Pseudomonas putida, (P. putida), are known to cause opportunistic infections.

Typically, the bacteria can live within a healthy body, and healthy people often carry the bacteria without realizing it because it doesn’t cause any harm. Mild infections can sometimes occur, leading to issues such as a swimmer’s ear or a hot tub rash.

For those with weakened immune systems or those who are already ill, an infection from Pseudomonas can be severe or even deadly.

This article discusses the strains of Pseudomonas, their effects, who is most at risk, and the antibiotics that treat these infections.  

Strains of Bacterial Pseudomonas

There are over 140 species of Pseudomonas. Most of them are considered saprophytic, meaning they cannot make their own food and typically feed on dead or decaying organic matter. For the most part, they are no threat to humans or human health.

However, roughly 25 species can cause infections in humans. Most species that lead to human disease drive opportunistic infections, which are infections that develop in people with weakened immune systems due to health conditions or medications they take that tamp down the immune system. The strains associated with opportunistic infections include:

• P. aeruginosa
• P. fluorescens
• P. putida
• P. cepacian
• P. stutzeri
• P. maltophilia
• P. putrefaciens

There are two species of the bacteria (P. mallei and P. pseudomallei) that cause the diseases known as glanders and melioidosis. The strains that are most likely to cause infection (P. aeruginosa and P. maltophilia) make up 80% of the clinical specimens of the bacteria recovered from samples from those who developed infections. The strain P. aeruginosa receives the most focus in clinical research and documentation.

Risk of Pseudomonas Infection

This species family of bacteria isn’t typically associated with human infections, except for a small number of strains. Those strains that cause infection are more likely to do so in people who are chronically ill or those with weakened immune systems.

In Non-Immunocompromised Individuals

People without compromised immune systems don’t have to worry too much about an infection caused by Pseudomonas because, typically, the bacteria do not cause any ill effects if they enter the body of a healthy person.

In some cases, healthy individuals could develop mild infections, such as swimmer’s ear (otitis externa) or a hot tub rash (pseudomonas folliculitis), if they come into contact with the bacteria. These infections are treatable and don’t tend to cause a lot of ill effects.

In Immunocompromised Individuals 

Since a Pseudomonas infection is considered opportunistic, meaning it thrives in people who are immunocompromised, these individuals are the most at risk of having severe complications from the bacteria.

For example, research shows that people with cystic fibrosis (CF) have a higher risk of life-threatening outcomes if they come into contact with the strain P. aeruginosa. This type of infection is a leading cause of morbidity (the state of being ill) and mortality (number of deaths) in people with cystic fibrosis.  

People with cystic fibrosis are also likely to experience chronic infections after coming into contact with the bacteria, which further leads to more severe and life-threatening outcomes. This is because, in cystic fibrosis, the health of the lungs is compromised.

Pneumonia, which is a lung infection that can cause severe complications and even death, is the most common infection caused by P. aeruginosa. The same strain is responsible for 10% to 20% of all ventilator-driven pneumonia cases. When these infections occur in immunocompromised individuals, the risk of death increases, with mortality rates sitting at roughly 34% to 42.8%.

Symptoms of Pseudomonas and Effects on Organs

While Pseudomonas can affect the entire body, some organs and body systems are more likely to experience the infection and its symptoms. They include:

Lungs

The lungs are a common area affected by Pseudomonas infections, specifically for those with lung diseases, including CF and chronic obstructive pulmonary disease (COPD). When the bacteria affect the lungs, pneumonia can result. Symptoms include:

• A cough with green, yellow, or bloody mucus
• Fever, sweating, and chills
• Shortness of breath and rapid, shallow breathing
• Chest pains that worsen upon deep breathing or coughing
• Low energy and fatigue
• Loss of appetite, nausea, and vomiting
• Confusion (typically in older adults)

Skin Injuries

Skin injuries, specifically burns, are known to be associated with Pseudomonas infections in hospitalized people. When a person develops an infection in the skin after a burn wound, the effects could be grave.

Symptoms of a wound infection include:

• Red or purplish discoloration in the burnt area or the surrounding skin
• Swelling in the area
• A change in color to the skin surrounding the burn or the burnt area
• Changes in how thick the burn is and how far into the skin it goes
• Discharge or pus that is green
• Fever

Ear Canal

Pseudomonas can get into the ear and cause infection to develop. These are typically mild and don’t lead to long-term effects. Swimmer’s ear is the most notable infection caused by Pseudomonas infections, with symptoms being:

• Redness or purpleness on the outer ear area
• Itchy ears
• Pain when touching or wiggling the earlobe
• Yellow or yellow-green pus draining from the ear that may or may not have an odor
• Swollen neck glands
• Swollen ear canal
• Hearing loss or muffled hearing
• Feeling as though the ears are full or clogged
• Fever

Urinary Tract

Urinary tract infections (UTIs) that develop while in the hospital due to Pseudomonas account for roughly 10% of all catheter-associated UTIs. The bacteria can be found in catheters used in hospital settings and can enter the urinary tract this way.

The symptoms associated with UTIs that are driven by a catheter include:

• Pain or burning in the lower abdomen below the stomach
• Fever
• Blood in the urine
• Burning during urination after removal of the catheter
• An increase in the frequency of urination after removing the catheter

Transmission: Where Do Pseudomonas Come From?

Pseudomonas are typically found in soil, water, and other environmental substances. When someone is exposed to the bacteria in the soil or water, they can develop an infection or carry the bacteria with them and be able to transmit it to someone else.

In healthcare settings, the spread of Pseudomonas can occur through contaminated hands, equipment, or surfaces.

When to See a Healthcare Provider 

Since Pseudomonas infections can turn severe reasonably quickly, especially in people with burn wounds, who spend time in a hospital or those who are immunocompromised, it’s vital to note the signs of infection and when to call a healthcare provider.

You should contact your healthcare provider when:

• A skin wound shows signs of infection.
• You have symptoms of an infection after a stay in the hospital.
• You have known exposure to the bacteria even without symptoms.
• You are immunocompromised and have signs of infection.
• You’re experiencing a high fever and severe shortness of breath.

Antibiotics for Pseudomonas

Pseudomonas infections are not always easy to treat. For that reason, several different first-line therapies can be used to clear up the infection. Some options include:

• Cefobid (cefoperazone)
• Ciloxan (ciprofloxacin)
• Fortaz (ceftazidime)
• Levaquin (levofloxacin)
• cefepime
• Timentin (ticarcillin-clavulanate)
• Zosyn (piperacillin-tazobactam)

Pseudomonas Antibiotic-Resistant Treatment

According to research, as many as 10% of Pseudomonas infections are antibiotic resistant. Because they can evade medication and thrive, they are challenging to treat. To address this issue, antipseudomonal drugs are used. Some options include:

• Aycaz (ceftazidmine-avibactam)
• Fetroja (cefiderocol)
• Recarbio (imipenem-relebactam)

Bacteriophage therapy, which uses bacteria-specific viruses to kill harmful pathogens, can also combat drug-resistant Pseudomonas infections. That said, this is a relatively new approach to Pseudomonas infections and, thus, isn’t widely used in clinical practice. Early trials with this type of therapy show promise.

Limiting Exposure to Pseudomonas

Limiting your exposure to Pseudomonas is the best way to prevent infection. You can do this by:

• Practicing good hygiene by keeping your hands clean at all times, cleaning and covering cuts and scrapes promptly, and avoiding contact with other people’s wounds or bandages
• Avoiding sharing towels, razors, and other personal care items
• Avoiding the overuse of antibiotics, taking them only as prescribed
• Being certain that healthcare workers wash their hands or wear gloves before touching you or any equipment that may used on you

Summary

For the most part, a Pseudomonas infection can be harmless. Most people who develop symptoms will only experience a mild infection that’s easily treated, such as swimmer's ear. In some cases, however, a Pseudomonas infection can be severe and life-threatening, especially for people with compromised immune systems or certain health conditions, such as cystic fibrosis.

Depending on their current state of health, people who become ill from the bacteria could require prompt medical attention. People who are immunocompromised and those who are hospital inpatients are at high risk for infection.

If you are at high risk, you can reduce your chances of getting the infection by practicing good hygiene, avoiding sharing personal items, and avoiding the overuse of antibiotics.