What is Mycobacterium kansasii Infection?
Mycobacterium kansasii is a type of non-tuberculosis mycobacterium (NTM), which is a group of bacteria that doesn’t cause tuberculosis but can lead to other types of infections. It has a unique feature that makes it easy to identify: it produces a yellow color when it’s exposed to light.
This type of bacteria grows slowly and was first described by Buhler and Pollack back in 1953. When looked at under a light microscope, M. kansasii looks like thick, beady, rectangular rods. These are a type of bacteria, known as gram-positive rods, that are longer than the rods of M. tuberculosis, the bacteria that causes tuberculosis.
In terms of the diseases it can cause, M. kansasii often leads to a long-lasting disease that affects the upper part of the lungs, creating hollow spaces called cavities. This disease resembles the ones caused by M. tuberculosis. The number of infections caused by NTM including M. kansasii has been increasing over the years, whereas the number of tuberculosis cases has been decreasing. However, there’s no clear information about the exact number of M. kansasii cases, although some studies suggest that they might be decreasing.
What Causes Mycobacterium kansasii Infection?
Mycobacterium Kansasii is a type of bacteria that grows slowly. It prefers temperatures of 32 degrees Celsius, but it can also thrive at 37 degrees. Interestingly, this bacteria’s characteristics are similar to other types of bacteria, namely M. marinum and M. szulgai. It’s worth noting that it can take more than a week to produce mature colonies.
Like other bacteria in its family, M. kansasii is strictly gram-positive, which is a fancy way of saying that it stains violet during a test used for identifying bacteria. It is unable to move, and it doesn’t form spores, a type of bacteria’s dormant stage. The colonies of this bacteria can have different looks, ranging from flat to raised and smooth to rough. When grown in the dark, these colonies start out without color but eventually turn yellow after being exposed to light. This is because they deposit a natural pigment called beta-carotene.
When compared to another bacteria, M. tuberculosis, M. kansasii looks longer and broader. Under the microscope, it appears beaded or cross-barred when stained with specific dyes.
There are various known forms of M. kansasii, as genetic studies have shown that there are at least seven subtypes. The most common subtype is most frequently found in human infections. These subtypes are very closely related and may be traced back to a single, common source. Clinical strains or types of this bacteria from Japan are just like those from Europe and the USA. The pathogenic or disease-causing strains are often associated with being Catalase positive.
M. kansasii is pretty common in the environment but is rarely found in soil. This bacteria has been documented in city tap water, swimming pools, fish tanks, fish bites, brackish water, and seawater. However, tap water seems to be the most common source or reservoir. Infections usually occur when people inhale aerosols containing the bacteria. The chance of getting infected in endemic areas is low. Human to human infection doesn’t occur frequently – only two documented cases are available where infection was noted in families. Rather than true human to human transmission, these cases are thought to be a result of shared environments, susceptibility or genetic predisposition.
Risk Factors and Frequency for Mycobacterium kansasii Infection
M. kansasii infection is often seen in males, typically between the ages of 45 to 62 years. The infection generally appears in particular areas or clusters, with a high occurrence rate in the southern and central states of the U.S., particularly Texas, Louisiana, Florida, Illinois, Kansas, and Nebraska. These infections have a greater likelihood of appearing in cities rather than rural locations, and are often linked with mining operations. They are also quite common in Wales and Poland. Areas with a high rate of HIV may also have a high rate of M. kansasii infections due to the vulnerability of people with HIV.
In the past, M. kansasii used to be the most common non-tuberculosis mycobacterial infection, especially during the 1960s and 70s. However, this changed with the rise of HIV in the 80s, which saw a resurgence of M. kansasii. Despite the decrease in instances over the years due to antiretroviral therapy, the infection can still occur in individuals with or without a functional immune system. It’s also important to note that accurate data on M. kansasii infections in transplant patients is lacking, as these infections are not reported regularly.
Typically, these infections can spread throughout the body in transplant patients. It’s mostly seen in those with lung disease and kidney transplant patients. M. abscesses, M. chelonae, and M. kansasii are the types of bacteria that are most likely to spread. Even in patients with HIV or late-stage AIDS, M. kansasii, typically manifests as a lung disease. A study in California found that the rate of these infections depended heavily on a person’s HIV status, with the highest rates seen in AIDS patients.
Signs and Symptoms of Mycobacterium kansasii Infection
Infections caused by the M. kansasii bacteria can appear in six different ways: lung disease, skin and soft tissue infections, infections of the muscles and skeleton, widespread disease, infections related to medical catheters, and lymph node infections. The most common presentation of M. kansasii infection is a chronic lung disease that forms holes in the upper lobe of the lungs. It can often be mistaken for lung tuberculosis at first. This infection can occur in adults of any age, gender, or race, with symptoms appearing in 85% of cases.
Lung infections due to M. kansasii usually cause symptoms such as:
- Coughing (91% of patients)
- Producing phlegm (85% of patients)
- Weight loss (53% of patients)
- Shortness of breath (51% of patients)
- Chest pain (34% of patients)
- Coughing up blood (32% of patients)
- Fever or sweats (17% of patients)
People at risk for M. kansasii infections are those who smoke, have lung conditions or diseases, are undergoing immunosuppression, have chronic kidney disease, are alcoholics, or have a current or past tuberculosis infection.
The most common form of M. kansasii infection is one that causes cavities in the lungs. However, the bacteria can also cause nodules or bronchiectasis. If left untreated, both cavity and nodular lung diseases will continue to exist and cause the lung structure to deteriorate. In patients with AIDS, lung disease might not result in cavities. Instead, swelling of the lymph nodes in the chest and infiltrates in the lung’s interstitial tissue are more common. In patients with a strong immune system, there is a higher likelihood of developing cavity lung disease.
The skin is the second most common organ to be infected by M. kansasii bacteria. Skin infections can include nodules, pustules, warty lesions, patches of red skin, abscesses, and ulcers. In people who are immunocompromised or have HIV, the skin presentation can be unusual and include bacteremia, bone infection, abscesses and cellulitis. Pericarditis, or inflammation of the heart’s outer lining, with cardiac tamponade, a condition in which fluid builds up around the heart, has been reported in HIV patients.
In the case of widespread disease, the symptoms can be vague and unspecific. They may include fever (present in 60% of patients), enlarged liver and spleen (in 40% of patients), lung infiltrates (25% of patients), and swollen lymph nodes (10% of patients). Bone infections, such as spinal osteomyelitis and sacroiliitis, are common with widespread M. kansasii diseases. Other complications such as abscesses in the psoas muscle, granulomas in the bone marrow or liver, and potential spleen abscesses have been reported.
In patients with advanced immune system weakening, co-infection of HIV and M. kansasii can occur, and it has been reported that these patients usually have a CD count of less than <50/mm3.
Testing for Mycobacterium kansasii Infection
Because the symptoms can be vague and easily confused with other diseases, identifying the specific germ responsible is necessary in order to confirm a diagnosis of M. kansasii, a type of bacteria that can cause lung disease. This bacteria is rarely found by mistake or from the environment, so if it’s detected, experts recommend that it be treated. Several tests, including a highly precise technique known as PCR (which stands for polymerase chain reaction), can determine if the bacteria is present.
To accurately diagnose M. kansasii, doctors don’t just rely on the test results. They also consider the patient’s symptoms and look at images taken of the patient’s lungs, much like a detective gathering clues. The American Thoracic Society and the Infectious Disease Society of America advise that this should include at least a chest X-Ray, or a more detailed scan called a CT scan if the X-ray doesn’t show any abnormal cavities in the lungs, along with positive results from a sputum culture test, which involves looking at the mucus that is coughed up from the lungs under a microscope. Furthermore, other diseases with similar symptoms should be ruled out.
The sputum culture test is considered positive, suggesting M. kansasii, when two consecutive sputum cultures come back positive, when one sample taken during a bronchoscopy (a procedure that allows your doctor to look at your airways) is positive, or when one sputum culture is positive along with observations that the disease has damaged the lung tissue.
Treatment Options for Mycobacterium kansasii Infection
The first choice of treatment for M. kansasii, an infection caused by a type of bacteria, typically involves the use of antibiotics like Rifampin, Ethambutol, and Isoniazid, along with a vitamin B6 supplement, Pyridoxine. This treatment is recommended by health authorities like the Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS). Usually, this therapy lasts for at least 12 months or until lab tests show no bacteria for a year while on treatment.
It’s important to note that M. kansasii are known to resist another drug, Pyrazinamide. The resistance to Isoniazid (INH) should be carefully considered, as a higher dose is needed for M. kansasii compared to a similar bacterium – M. tuberculosis. In general, treatment plans involving Rifampin have low chances of failure and recurrence. For patients whose infection is resistant to Rifampin, a combination of other drugs like Clarithromycin or Azithromycin, along with Moxifloxacin, Ethambutol, Sulfamethoxazole, or Streptomycin can be used.
For patients with HIV, the strategy for treating M. kansasii involves using a specific group of antiviral drugs called NRTI, which allows full use of Rifampin. If the HIV treatment includes a specific kind of drugs like Darunavir or Atazanavir (protease inhibitor) or Efavirenz or Nevirapine (non-nucleoside reverse transcriptase inhibitor), then Rifabutin can be used instead of Rifampin. Health professionals need to be careful when adding Clarithromycin to a treatment plan, as it can increase the chance of negative side effects.
During treatment, patients will often have to provide phlegm samples to check the success of the treatment and that the bacteria is being eradicated. X-rays may be used to monitor the disease, though improvement in lung health may take time. Regular check-ups will be conducted to monitor for any adverse effects of the medications and potential interactions between different prescribed drugs.
What else can Mycobacterium kansasii Infection be?
Some conditions that could potentially impact your health include:
- Tuberculosis, which is caused by Mycobacterium tuberculosis
- Non-tuberculous mycobacteria (NTM), like MAC (Mycobacterium avium complex)
- Fungal infections from endemic fungi
- Infections caused by Actinomyces bacteria
- Cancer
- Wegener’s granulomatosis, an uncommon disease that causes inflammation of blood vessels
What to expect with Mycobacterium kansasii Infection
With the right treatment, the outlook is usually positive. However, the mortality rate can rise up to 50% in HIV patients infected with M. kansasii. For HIV patients who have a lung infection caused by M. kansasii, survival rate is dependent on a few factors. These include a higher count of CD4 cells (these are a type of white blood cell that fights infection), negative smear microscopy (this means the lab tests didn’t find any bacteria in the samples), treatment with antiretroviral therapy (drugs used to manage HIV), and proper treatment for M. kansasii.
Possible Complications When Diagnosed with Mycobacterium kansasii Infection
Complications of certain diseases can spread throughout the body. This can often affect the bones, leading to conditions like vertebral osteomyelitis and sacroiliitis, which are related to inflammation and damage to the spine and sacroiliac joints respectively. Other issues may include pneumothorax, which is a collapsed lung, and a Psoas abscess, a deep infection in the hip flexor muscles. Some individuals may develop bone marrow or liver granulomas, which are small areas of inflammation in these organs, and possibly even abscesses, or pus-filled areas, in the spleen. Another very rare yet serious complication is called meningoencephalitis, an inflammation of the brain and its surrounding membranes, which unfortunately often results in death.
Possible Complications:
- Widespread disease throughout the body
- Vertebral osteomyelitis (inflammation of the vertebra)
- Sacroiliitis (inflammation of the sacroiliac joints)
- Pneumothorax (collapsed lung)
- Psoas abscess (infection in the hip flexor muscles)
- Bone marrow granuloma (small areas of inflammation in the bone marrow)
- Liver granuloma (small areas of inflammation in the liver)
- Possible spleen abscesses (pus-filled areas in the spleen)
- Meningoencephalitis (inflammation of the brain and surrounding membranes), which can lead to death
Preventing Mycobacterium kansasii Infection
Patients should understand that if M. kansasii (a type of bacteria that can cause lung infections) is detected and treated early, they usually have a good chance of recovery. However, the treatment can take quite a long time. It’s really important for patients to stick with the treatment for the full length of time recommended by the doctor. If the treatment is stopped too soon, there’s a high chance that the infection could come back.
