The AMR Narrative

Carbapenem-resistant Pseudomonas aeruginosa (CRPA)

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What is Carbapenem-resistant Pseudomonas aeruginosa (CRPA)?

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a type of Pseudomonas aeruginosa bacteria resistant to carbapenems, a type of last-line antibiotics used to treat serious multidrug-resistant bacterial infections.

Unfortunately, CRPA bacteria can produce substances (called carbapenemases) that break down carbapenems and other so-called beta-lactams antibiotics (such as penicillin), making these medications ineffective. Some CRPA bacteria are even resistant to all available antibiotics, causing infections very difficult to treat.

Moreover, CRPA can share the genetic code with other bacteria, rapidly spreading resistance. That is why CRPA is considered a serious public health threat, and has been listed among the top priority bacterial pathogens to guide discovery, research and development of new antibiotics by the World Health Organization (WHO).

What is Pseudomonas aeruginosa?

To understand CRPA, it is important to know what Pseudomonas aeruginosa is.

Pseudomonas aeruginosa is a bacterium (bacteria), gram-negative, and rod-shaped.

It can cause various types of infections ranging from mild to serious ones. Life-threatening conditions primarily occur in healthcare settings, such as hospitals and nursing homes, and affect people at high risk, such as those ones with a weakened immune system.

Where can Pseudomonas aeruginosa be found?

Pseudomonas aeruginosa is commonly found in the environment, in soil and especially in water.

Taps, sinks, toilets, drains, plumbing parts, hot tubs, and inadequately chlorinated swimming pools are common reservoirs. In hospital settings these bacteria can be found also in soap bars, sanitizers, disinfecting solutions, respiratory therapy equipment, endoscopes, and endoscope washers.

Occasionally, Pseudomonas aeruginosa can be present in moist parts of the body, like armpits or genital area.

How can Pseudomonas aeruginosa spread?

Since Pseudomonas aeruginosa lives in the environment, can be spread to people when they are exposed to water or soil contaminated with these microorganisms.

In healthcare settings bacteria can spread from person to person by skin contact (through healthcare workers’ contaminated hands), or contaminated equipment or surfaces.

Pseudomonas aeruginosa infections are commonly acquired in hospitals or nursing homes.

Which infections can Pseudomonas aeruginosa cause?

Pseudomonas aeruginosa can cause mild infections in healthy people, but also life-threatening infections in people considered at risk (see Who is at risk of a Pseudomonas aeruginosa infection).

These infections may include:

• Skin and soft tissue infections. Bacteria can infect skin (for example, hot-tub folliculitis, a mild infection of hair roots), and even cause serious deep infections of muscles, tendons, ligaments, and fat. These conditions are more common in people with pressure sores, burns, and wounds due to injuries or surgery.
• Keratitis. It occurs when Pseudomonas aeruginosa bacteria infect and damage the cornea (the transparent and external part of the eye), often permanently. It may result from injuries, or from contamination of contact lenses or contact lens solution.
• External otitis. Water containing the bacteria can enter the ear during swimming, causing an infection of the ear canal skin. It can turn into a severe infection, especially in patients with diabetes.
• Bacteremia. When bacteria overcome the defence line of the skin, it can travel inside the bloodstream, and infect almost any site in the body.
• Pneumonia. The infection of the lung is more common in patients hospitalized with tracheal intubation and mechanical ventilation, or with chronic lung diseases (such as cystic fibrosis).
• Endocarditis. In this serious and potentially deadly condition, bacteria stick to one of the valves inside the heart after spreading into the bloodstream.
• Urinary tract infections. These types of infections are more likely in people with urinary catheters.
• Osteomyelitis. It occurs when Pseudomonas aeruginosa bacteria target a bone through the bloodstream.
• Meningitis. In this condition, bacteria can infect the meninges (the membranes covering the brain and spinal cord).
• Sepsis. It is the extreme and overactive response of the body to an infection. Sepsis is a life-threatening emergency, and requires immediate treatment.

Who is at risk of a Pseudomonas aeruginosa infection?

Anyone can develop a Pseudomonas aeruginosa infection, but certain groups of people are at greater risk than others, including people:

• with chronic illnesses, such as cancer, diabetes, cystic fibrosis, kidney or liver diseases, rheumatoid arthritis;
• with a weakened immune system, such as from HIV, immunosuppressants (medications which slow or stop the response of the immune system), or cancer chemotherapy;
• with urinary or intravenous catheters;
• with breathing tubes;
• with severe burns;
• with wounds due to surgical interventions;
• who are in healthcare facilities, such as hospitals.

How are Pseudomonas aeruginosa infections diagnosed?

To correctly diagnose an infection caused by Pseudomonas aeruginosa, first of all your physician will perform a physical examination and ask you about symptoms and risk factors. Guided by these elements, your doctor will be able to choose the most appropriate diagnostic tests.

Laboratory tests can identify Pseudomonas aeruginosa using a sample taken from an area of the patient’s body likely to contain the microbe (for example, blood or other tissue or fluid). These samples are sent to a laboratory to grow the microorganism over time using a media on a petri dish (culture) and identify it. Then susceptibility tests can be carried out to determine which antibiotics are most effective against it, to start the most appropriate antibiotic therapy. Understanding which antibiotic will work best is especially key to carbapenem-resistant Pseudomonas aeruginosa (CRPA) as this type of resistant Pseudomonas aeruginosa bacteria may only respond to certain medicines.

Novel molecular DNA tests can not only rapidly detect the bacteria directly in a specimen but at same time provide antibiotic resistance results, making it much easier for the physician to choose appropriate antibiotics. In some cases, they may respond to none.

Finally, depending on the type of infection, your physician may recommend additional tests, such as imaging tests.

How are Pseudomonas aeruginosa infections treated?

As Pseudomonas aeruginosa is a bacterium, therapy is represented by antibiotics. The antibiotic may vary according to the type and severity of the infection, and the results of susceptibility tests. Indeed, some infections, such as those ones caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA), are resistant to several antibiotics.

Depending on the site and the severity of infection, the medication could be in the form of eye drops, ear drops, creams applied to the skin, or tablets to swallow. Severe infections may require intravenous antibiotics (the medication is given through a drip or a tube).

Mild infections can be easily treated with antibiotics at home. However, severe infections require to be treated in hospital, and need additional therapies.

Unfortunately, due to the increasing resistance to the available antibiotics, Pseudomonas aeruginosa infections are becoming more difficult to treat, and sometimes more than one antibiotic is needed.

How can Pseudomonas aeruginosa infections be prevented?

Following these precautions can lower your risk of getting a Pseudomonas aeruginosa infection. Moreover, they help to reduce your chances of spreading bacteria to others, as well.

• Wash your hands thoroughly and regularly with soap and running water. Then dry them with a clean towel, or a disposable paper towel. If you are not able to wash your hands, you can use an alcohol-based hand sanitizer. Remember: hand hygiene is your best protection against infections.
• Clean surfaces. Use disinfecting products to clean especially high-touch surfaces, such as your cell phone, doorknobs, and light switches.
• Avoid unclean swimming pools and hot tubs. Make sure they are properly maintained and chlorinated.
• Drink clean water. If you do not have clean water available, drink bottled, canned, or boiled water.
• Wash fruits and vegetables before eating.
• Keep wounds clean and covered with dry and sterile bandages until they heal, to prevent the bacteria from spreading.

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