Nocardia

What is Nocardia?

Nocardia is a type of bacteria that was first discovered in 1888 by a man named Edmond Nocard. It’s aerobic (it can live and grow where there is oxygen), acts like fungi, produces an enzyme called catalase, has a positive reaction to a common bacteria test called the gram stain, and looks like branching filaments under a microscope. This bacteria is found all over the world in many different environments.

Infections caused by Nocardia can lead to different symptoms based on where the infection occurs in the body. The most common sites of infection include the lungs and skin. However, the infection can also spread to other parts of the body, and it can affect the central nervous system, which includes the brain and spinal cord.

Nocardia typically affects people who have weakened immune systems. But it’s important to note that people with healthy immune systems can also get infected, especially with the skin form of the disease.

What Causes Nocardia?

Nocardia is a type of bacteria that is found almost everywhere in the environment, such as in fresh and salt water, dust, soil, and decaying plants and organic matter. It is believed that most Nocardia infections happen when people breathe in the bacteria from the environment, most commonly from dust. This causes pulmonary nocardiosis, a form of the infection that affects the lungs.

On the other hand, cutaneous nocardiosis, which affects the skin, usually happens when the bacteria enter the body through a wound or cut. Other ways you can get the infection include being in a hospital where the bacteria is present or through central venous catheters, which are tubes doctors insert into a large vein in your neck, chest, or leg to give medications or collect blood.

Once a person has a Nocardia infection, even if they don’t have symptoms, it can spread within the body through the blood or through nearby tissue. It’s important to note that people with weakened immune systems are more likely to get nocardiosis and the infection is likely to spread throughout their body.

Risk Factors and Frequency for Nocardia

The CDC has reported that nocardiosis, a particular type of infection, affects 500 to 1,000 people in the US every year. It’s difficult to determine how frequently this infection occurs worldwide, but estimates suggest that its incidence is growing. This increase is believed to be connected to a rising global population and more individuals experiencing a compromised immune system. Nocardiosis can affect anyone, regardless of age or race, but it’s three times more common in men than women.

Nocardiosis often occurs in patients with weakened immune systems, making up 60% of all nocardiosis cases. However, it’s important to note that even people with a healthy immune system can get infected – in fact, they constitute up to 33% of all cases, with skin infections being particularly common in these individuals.

The infection can spread more easily both through the skin and lungs in patients with compromised immune systems. As such, this condition is often associated with situations or diseases that weaken the immune system. These include:

HIV (the most common underlying condition)
Cancer
Going through chemotherapy
Using corticosteroids (found in more than half of patients with Nocardia infection, according to one study)
Having received a solid organ transplant (especially lung transplants)
Having received a stem cell transplant from a donor
Diabetes
Autoimmune diseases
Chronic lung diseases such as COPD (many of these patients are on corticosteroid therapy)

Essentially, any condition that weakens the body’s cell-based defense mechanism (cell-mediated immunity) increases the risk of Nocardia infections.

Signs and Symptoms of Nocardia

Nocardiosis is a disease that can create different symptoms depending on where in the body it shows up. Pulmonary nocardiosis, which affects the lungs, can lead to fever, weight loss, night sweats, a persistent cough, and chest pain. If the infection moves to the central nervous system (CNS), a person might experience headaches, feel weak, become confused, or even have seizures. Cutaneous nocardiosis, which occurs on the skin, can result in ulcers, knots that sometimes leak fluid, and can potentially spread to the nearest lymph nodes.

If someone has a weakened immune system and develops nocardiosis, delaying the diagnosis can lead to unsuccessful treatments and a poorer chance of recovery. That’s why it’s really important for medical labs to know if doctors suspect a Nocardia infection – it means they can quickly identify the exact type of Nocardia and how best to treat it.

Fever
Weight loss
Night sweats
Cough
Chest pain
Headache (if infection spreads to the CNS)
Weakeness (if infection spreads to the CNS)
Confusion (if infection spreads to the CNS)
Seizures (if infection spreads to the CNS)
Skin ulcers (if cutaneous nocardiosis occurs)
Nodules that sometimes drain (if cutaneous nocardiosis occurs)

Testing for Nocardia

Nocardiosis, a type of infection, can be tough to diagnose because the symptoms and signs are quite general and can be confused with other illnesses. The primary way doctors confirm this infection is by taking a sample, like spit (sputum), a skin tissue sample (biopsy), pus from an abscess, or a sample from a lung washing procedure (bronchoalveolar lavage), and growing it in a lab to see if the Nocardia bacteria is present. This process can take three to five days. If the infection has spread to the lungs or throughout the body, a blood test might be conducted, however, it’s rare to find Nocardia bacteria in the blood.

Medical images such as CT scans or chest X-rays can be very helpful, particularly for diagnosing lung infections caused by Nocardia bacteria. But the pictures can show a variety of issues, like uneven lumps in the lungs that might form cavities, widespread lung inflammation, lung abscesses, or fluid around the lungs. These imaging results, along with a patient’s history and physical exam, can support a suspicion of nocardiosis.

For all patients with nocardiosis (except those with a specific type of the infection called mycetoma), a brain CT scan or MRI is usually suggested. This is because if the initial infection spreads, it often goes to the brain about 44% of the time. An abscess, or a pocket of pus, in the brain is the most common abnormal finding on these images. In cases where the doctor suspects nocardiosis has caused meningitis (inflammation of the membranes surrounding the brain and spinal cord), a procedure called lumbar puncture, or spinal tap, is undertaken to collect fluid for testing. Nocardial meningitis is rare but it resembles other types of bacterial meningitis.

If your doctor thinks you might have a Nocardia infection, they will alert the lab. This is so the lab can perform certain tests, like gram staining and modified acid-fast staining, to speed up the diagnosis, as the culture process can take several days. This also helps start treatment while waiting for the results of antibiotic sensitivity tests. With new technology, such as PCR and 16S rDNA sequencing, diagnoses made using Nocardia species may be faster and more accurate, which can help speed up treatment.

Treatment Options for Nocardia

Since the 1940s, Nocardia infections (caused by a type of bacteria) have been primarily treated with a group of medications called sulfonamides. The most commonly used sulfonamide in the U.S. is trimethoprim-sulfamethoxazole (TMP-SMX). However, it’s been observed that certain strains of Nocardia bacteria have developed resistance to TMP-SMX. Particularly, Nocardia species like N. farcinica, N. nova, and N. otitidiscaviarum have shown increased resistance to multiple drugs.

This challenge with resistance has led many healthcare providers to use a combination of drugs, especially for serious, widespread, or brain-involved infections. Typically, this includes TMP-SMX, amikacin, and imipenem. It’s crucial to select medications that can penetrate the central nervous system (or CNS, which includes the brain and spinal cord) well when the infection involves the CNS. TMP-SMX and ceftriaxone are examples of such medications. A newer medication, linezolid, which belongs to the oxazolidinones class of drugs, has also shown exceptional effectiveness against all known Nocardia species.

Other medications that can be considered for treating Nocardia infections include:

Carbapenems, such as imipenem, meropenem, or ertapenem.
Quinolones, particularly moxifloxacin.
Tetracyclines like minocycline.

The length of treatment depends on the location of the infection and the immune status of the person. For patients with infection in the lungs or in multiple places excluding the CNS, treatment typically lasts 6-12 months. If a person’s immune system is compromised, or the infection affects their CNS, treatment will be required for at least 12 months.

Prophylaxis, which is the use of medication to prevent disease, can also play a significant role. Particularly, patients with HIV seem to be more susceptible to Nocardia infections. They are usually given TMP-SMX as a preventative measure against diseases like Pneumocystis jiroveci pneumonia (PJP) and toxoplasmosis. This preventative treatment also appears to reduce Nocardia infections.

It can be very hard to tell Nocardia apart from other types of infections. When trying to figure out what’s caused an infection in specific areas of the body, doctors would consider different possibilities:

For lung infections:

Fungal infections like aspergillosis, mucormycosis, histoplasmosis, blastomycosis, and cryptococcosis
Actinomyces infection
Mycobacterial infections such as Mycobacterium tuberculosis
Lung cancer

For skin infections:

Superficial cellulitis caused by group A strep (GAS), staph aureus
Lymphocutaneous infections like sporotrichosis, Mycobacterium marinum
Late-stage Mycetoma caused by actinomycosis, fungal infections
Other possibilities: cutaneous leishmaniasis, Cryptococcus

For brain and nervous system (CNS) infections:

Cancer
Bacterial abscess
Vascular infarction
Other possibilities: toxoplasmosis, mycobacterial tuberculosis, fungal infection, cysticercosis

By thinking through these possibilities, doctors can work towards an accurate diagnosis.

What to expect with Nocardia

The severity and outcomes of Nocardia, a type of infection, depend on where the infection is located, how widespread it is, and the overall health of the individual. How well someone might recover from a Nocardia infection can vary.

Here’s a general idea of recovery rates based on where the infection is:

For infections in the skin and soft tissues: nearly everyone recovers fully
For infections in the area around the lungs: about 80% of people recover fully. Interestingly, back in the 1940s, this type of infection was nearly always fatal. However, with the introduction of a type of antibiotics known as sulfonamides and other combined antibiotic treatments, the number of people who die from this infection has dropped significantly. Nowadays, between 14% to 40% of people might die from this infection.
For widespread Nocardia infections (also known as ‘disseminated nocardiosis’): only about 3% recover fully
For infections involving the Central Nervous System (which includes the brain and spinal cord): between 50% to 85% of people recover fully

Possible Complications When Diagnosed with Nocardia

If an infection spreads from its initial location, it can cause complications. This is particularly true in the case of a lung infection known as pulmonary nocardiosis. If this infection moves to the nearby areas, it may cause inflammation of the heart lining, a condition known as pericarditis, and a disease condition called superior vena cava syndrome, depending on the extent and location of the spread.

In addition to these, when the infection spreads to the brain, several complications, such as focused neurological deficits and meningitis, can occur. Delaying diagnosis in patients with lowered immunity and nocardiosis can lead to unsuccessful treatment and poor projected outcomes.

Therefore, if there is any chance that a patient might be infected with Nocardia, it’s essential to let the lab know. This arm the lab with adequate preparation to identify the specific species and their antibiotic resistance patterns as swiftly as possible. With the help of tools like PCR and 16S rDNA sequencing, we can identify Nocardia species much faster.

Common Effects:

Pericarditis
Superior vena cava syndrome
Focal neurologic deficits
Meningitis
Delayed diagnosis contributing to failure of treatment

Preventing Nocardia

Nocardia is a common type of bacteria here on earth, that can cause various types of infections. People with weakened immune systems, such as those with HIV, are more prone to infections caused by this bacteria, particularly those affecting their lungs and central nervous system, which includes the brain and spinal cord.

If these individuals are deemed to be at a higher risk, they can be provided with a preventive drug known as TMP-SMX. However, it’s important to note that there are many types of Nocardia which may resist this drug, hence the doctor might have to offer a combination of drugs.

While individuals with weakened immune systems are particularly at risk, those with healthy immune systems can also get infected, especially with the skin infection form of the disease. This mostly happens when a skin injury comes in contact with things like soil or decomposing materials.

Therefore, a practical way to minimize this risk is by wearing items like closed shoes and gloves, especially when working in places like construction sites or gardens that might have these disease-causing bacteria. If you get a wound, it’s important to cleanse it thoroughly. If the wound turns red, swells, gets warm or starts discharging, it’s crucial to reach out to a general practitioner.

Despite being infrequent, doctors should always consider the possibility of a Nocardia infection if the common causes of the patient’s symptoms are ruled out.

Frequently asked questions

Nocardia is a type of bacteria that can live and grow where there is oxygen. It acts like fungi, produces an enzyme called catalase, has a positive reaction to the gram stain test, and looks like branching filaments under a microscope. It is found all over the world in various environments.

The CDC has reported that nocardiosis affects 500 to 1,000 people in the US every year.

The signs and symptoms of Nocardia infection can vary depending on the location in the body. Here are the different signs and symptoms associated with Nocardia: 1. Pulmonary Nocardiosis (affects the lungs): - Fever - Weight loss - Night sweats - Persistent cough - Chest pain 2. Central Nervous System (CNS) involvement: - Headache - Weakness - Confusion - Seizures 3. Cutaneous Nocardiosis (occurs on the skin): - Skin ulcers - Nodules that sometimes drain fluid It is important to note that individuals with a weakened immune system are at a higher risk of developing Nocardia infection. Delaying the diagnosis can lead to unsuccessful treatments and a poorer chance of recovery. Therefore, it is crucial for medical labs to be informed if doctors suspect a Nocardia infection so that the exact type of Nocardia can be identified and the most effective treatment can be administered.

Most Nocardia infections happen when people breathe in the bacteria from the environment, most commonly from dust. It can also enter the body through a wound or cut, or through central venous catheters.

When diagnosing Nocardia, a doctor needs to rule out the following conditions: - For lung infections: fungal infections like aspergillosis, mucormycosis, histoplasmosis, blastomycosis, and cryptococcosis, actinomyces infection, mycobacterial infections such as Mycobacterium tuberculosis, and lung cancer. - For skin infections: superficial cellulitis caused by group A strep (GAS), staph aureus, lymphocutaneous infections like sporotrichosis, Mycobacterium marinum, late-stage Mycetoma caused by actinomycosis, fungal infections, and other possibilities such as cutaneous leishmaniasis, Cryptococcus. - For brain and nervous system (CNS) infections: cancer, bacterial abscess, vascular infarction, and other possibilities such as toxoplasmosis, mycobacterial tuberculosis, fungal infection, cysticercosis.

The tests needed for Nocardia include: - Taking a sample (sputum, skin tissue, pus, or lung washing) and growing it in a lab to see if Nocardia bacteria is present. - Blood test (if the infection has spread to the lungs or throughout the body, although it is rare to find Nocardia bacteria in the blood). - Medical imaging such as CT scans or chest X-rays to diagnose lung infections caused by Nocardia bacteria. - Brain CT scan or MRI for all patients with nocardiosis (except those with mycetoma) to check for brain involvement. - Lumbar puncture (spinal tap) to collect fluid for testing if nocardiosis has caused meningitis. - Gram staining and modified acid-fast staining to speed up the diagnosis. - Antibiotic sensitivity tests to determine the most effective treatment. - PCR and 16S rDNA sequencing for faster and more accurate diagnoses. - Other tests may be ordered based on the specific symptoms and presentation of the patient.

Nocardia infections are primarily treated with a group of medications called sulfonamides, with the most commonly used sulfonamide being trimethoprim-sulfamethoxazole (TMP-SMX). However, certain strains of Nocardia bacteria have developed resistance to TMP-SMX. In such cases, a combination of drugs is often used, especially for serious, widespread, or brain-involved infections. This combination typically includes TMP-SMX, amikacin, and imipenem. Medications that can penetrate the central nervous system (CNS) well, such as TMP-SMX and ceftriaxone, are crucial when the infection involves the CNS. Linezolid, a newer medication belonging to the oxazolidinones class of drugs, has also shown exceptional effectiveness against all known Nocardia species. Other medications that can be considered include carbapenems, quinolones, and tetracyclines. The length of treatment depends on the location of the infection and the immune status of the person, ranging from 6-12 months for lung or non-CNS infections to at least 12 months for CNS infections or compromised immune systems. Prophylaxis with TMP-SMX is also used for patients with HIV to prevent Nocardia infections.

When treating Nocardia, there are several potential side effects and complications that can occur. These include: - Pericarditis: Inflammation of the heart lining. - Superior vena cava syndrome: A condition caused by the compression or obstruction of the superior vena cava, a large vein that carries blood from the upper body to the heart. - Focal neurologic deficits: Neurological symptoms that are localized to a specific area of the body, such as weakness or loss of sensation. - Meningitis: Inflammation of the membranes surrounding the brain and spinal cord. - Delayed diagnosis contributing to failure of treatment: If the infection is not diagnosed promptly, it can lead to unsuccessful treatment and poor outcomes.

The prognosis for Nocardia depends on the location and severity of the infection, as well as the overall health of the individual. Here is a general idea of recovery rates based on the location of the infection: - Skin and soft tissue infections: Nearly everyone recovers fully. - Infections around the lungs: About 80% of people recover fully, but between 14% to 40% might die from this infection. - Widespread Nocardia infections: Only about 3% recover fully. - Infections involving the Central Nervous System: Between 50% to 85% of people recover fully.

General Practitioner