What is Arcanobacterium haemolyticum Infections?

Arcanobacterium haemolyticum, previously known as Corynebacterium haemolyticum, is a type of bacteria. It’s known for two main things: stopping the breakup of red blood cells by another type of bacteria, Staphylococcus aureus, in a specific test and improving the breakdown of red blood cells by Streptococcus agalactiae in a reverse version of the same test. This bacterium was first identified in 1946 when it caused sore throats and open skin sores among American soldiers in the Pacific Islands.

Most infections from A haemolyticum are connected to head and neck infections like sore throats and sinusitis, mainly in children and teenagers. It can also cause skin and soft tissue infections, typically in people with compromised immune systems. In rare cases, it can also cause other types of infections, such as bloodstream infections, heart valve infections, bone infections, sepsis, abscesses in the brain, and pneumonia.

Without lab testing, it can be a challenge to identify whether a sore throat is caused by a virus or bacteria. The most common bacterial cause of a sore throat is S pyogenes, but A haemolyticum is also a cause, albeit less common. While both bacteria cause similar symptoms, it’s important to consider A haemolyticum when diagnosing a sore throat to ensure accurate treatment.

When someone has a sore throat caused by A haemolyticum, they may also develop a fever and a scratchy rash. This rash can be mistaken for the rash caused by S pyogenes bacteria or a viral rash. Diagnosis can be delayed due to these similarities, as well as the fact that the signs of red blood cell breakdown caused by A haemolyticum take longer to appear than those caused by S pyogenes. The bacterium is also harder to grow in lab tests, adding to diagnostic challenges. It’s vital to quickly recognize and treat infections with antibiotics and other supportive care measures to prevent permanent health damage.

What Causes Arcanobacterium haemolyticum Infections?

A haemolyticum is a type of germ that doesn’t move, requires oxygen, and is known for breaking down red blood cells. It’s usually found on the skin and in the throat as part of our body’s normal collection of germs. It’s typically passed from person to person through particles sent into the air when someone talks, coughs, or sneezes.

There are two types of A haemolyticum: smooth and rough. The smooth type is more often linked with infections in soft tissues and shows up as evenly shaped colonies when grown in a lab. It can break down certain types of sugar but can’t produce an enzyme called beta-glucuronidase, which helps the body process certain substances. In contrast, the rough type doesn’t break down red blood cells and can produce this enzyme, but can’t break down the same types of sugar. It forms unevenly shaped colonies when grown in the lab and is more often linked with sore throats.

When A haemolyticum is grown in a lab, it forms colonies that break down red blood cells and can be seen under a microscope as a type of dense, round germ. It grows best at body temperature on a substrate made with blood and 5-10% CO2. The breakdown of red blood cells is most noticeable when human or horse blood is used, but if sheep’s blood is used, the growth might be slower and takes up to 3 days. This slower growth might be missed, unless the lab is told to watch the culture for longer. Identification of A haemolyticum is confirmed by a test that shows it doesn’t produce an enzyme called catalase and a test that confirms it can break down a certain type of protein.

Extra challenges in diagnosis can come up since A haemolyticum can be confused with other bacteria when it first appears on the growth medium in the lab. Its shape can make it look like normal germs or misidentified as other types of bacteria. However, it can be differentiated by a test showing it doesn’t produce the enzyme catalase and that it breaks down red blood cells, which differentiates it from some bacteria. Additionally, it can’t break down a certain type of sugar and a test shows it can break down a certain type of protein, which differentiates it from another bacteria. Its appearance distinguishes it from Streptococcus species.

Risk Factors and Frequency for Arcanobacterium haemolyticum Infections

A haemolyticum is a bacterium that’s normally found on our skin and in our throat. It isn’t usually a problem, but it can cause issues that often go unnoticed because doctors don’t routinely check for it. This bacterium can cause throat infections and other conditions in the head and neck, especially in healthy kids and teenagers. Around 0.5% to 2.5% of children with a throat infection may actually have an A haemolyticum infection.

The bacteria are particularly troublesome for older people or those with weakened immune systems, including people with type 2 diabetes. Patients with A haemolyticum can develop persistent skin ulcers, abscesses, or skin inflammation, often in combination with other bacteria. In some cases, bone infections have been traced back to an A haemolyticum skin infection.

In rare circumstances, A haemolyticum may cause more serious problems, such as brain abscesses, pneumonia, heart infection, pus in the chest cavity, and potentially lethal bacteremia. People with type 2 diabetes, cancer, or a weakened immune system are at greater risk of developing a serious infection from A haemolyticum.

Signs and Symptoms of Arcanobacterium haemolyticum Infections

When dealing with a patient who has a sore throat and fever, a comprehensive review of their medical history and a thorough physical examination are required. This is due to many infections displaying similar symptoms, making them hard to distinguish based on these aspects alone. One such non-streptococcal pharyngitis is due to A haemolyticum, which tends to affect individuals between the ages of 15 and 25.

Patients suffering from this infection can exhibit a range of symptoms that vary in severity, from mild throat infections to more serious diphtheria-like illnesses. Common symptoms include a sore throat, redness in the throat, and a discharge from the throat, which are present in almost every case. Fever is also commonly seen, with about two-thirds of the patients showcasing swollen neck glands.

An erythematous rash, or red blotchy skin, is another common symptom in many cases. This rash often feels like sandpaper and can cause itchiness. Typically, the rash starts on the hands and feet before spreading to the neck, chest, and back while sparing the face, palms, and soles. Usually, the rash appears a few days after the sore throat and lasts for a few days. However, be aware that these symptoms are indistinguishable from those of scarlet fever caused by S pyogenes, except for a few key features such as strawberry tongue or Pastia lines which are not present in this case.

Some cases of A haemolyticum infection can have serious complications such as Lemierre syndrome. Furthermore, patients with this bacteria in their skin or soft tissues tend to be older and have underlying diseases. The symptoms include chronic skin ulcers, abscesses, or cellulitis. In rare instances, this bacterium can be invasive and cause brain abscesses, pneumonia, endocarditis, pyothorax, and bacteremia. Those with weakened immune systems may be at higher risk for these serious infections such as meningitis and bacteremia.

Testing for Arcanobacterium haemolyticum Infections

Testing for the bacterium A haemolyticum can be tricky and complex. This is because rapid antigen tests, commonly used by healthcare professionals, focus on distinguishing it from S pyogenes, the most common cause of throat infections. However, a negative result from these rapid tests doesn’t immediately disprove the presence of S pyogenes or confirm the presence of A haemolyticum, which may need additional testing.

When it comes to identifying A haemolyticum, it’s primarily recognized by the formation of β-hemolytic colonies. These are colonies of bacteria that break down blood cells and are optimal for growing in blood or serum-enriched environments. They carry several characteristics, like being negative for a catalase, oxidase, indole, and urease tests, but they test positive in the reverse CAMP test.

One common problem faced by labs is the fast growth rate of a streptococcus bacterium on sheep blood agar, which often overshadows the slower-growing A haemolyticum. This can result in inaccurate or missed detection of A haemolyticum. To prevent this, labs should be informed to lengthen the observation period, so they don’t dispose off the culture prematurely.

Another challenge is that A haemolyticum can look very similar to other bacteria in its early stages of growth, which can cause confusion. For a clear distinction, the presence of β-hemolysis and a negative catalase test can differentiate it from Corynebacterium species. Meanwhile, the inability to break down a sugar known as xylose and a positive reverse CAMP test can distinguish it from A pyogenes. Microscopic morphology can help differentiate it from Streptococcus species.

The majority of matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry databases, a technology used for bacterial identification, currently include A haemolyticum. This technology provides a speedy diagnosis if it’s available in the laboratory.

Treatment Options for Arcanobacterium haemolyticum Infections

Antimicrobial resistance is a big issue when dealing with infections, especially when prescribing immediate treatments. Unfortunately, there’s limited information about susceptibility testing for A haemolyticum, which is used to see how sensitive a microbe is to an antibiotic. The information we do have comes from a few older studies that use different testing methods, making it hard to compare results.

Studies suggest that A haemolyticum tends to respond well to antibiotics like penicillins, tetracyclines, and macrolides, but doesn’t respond to trimethoprim-sulfamethoxazole. However, there have been cases where the bacteria is resistant to tetracyclines, macrolides, clindamycin, and penicillin. Penicillin and macrolides are typically the go-to antibiotics for treatment.

Antimicrobial susceptibility testing is really important if a culture (a sample of cells) is available. This testing helps make sure the treatment will work and can be customized based on the test results if needed.

Sore throat, also known as acute pharyngitis, is a common infection that can be caused by different types of bacteria and viruses. Bacterial causes may include S. pyogenes, Mycoplasma pneumoniae, and Neisseria gonorrhea, while viral causes can include Epstein-Barr virus, cytomegalovirus, measles, and coronaviruses such as the COVID-19 virus. It can sometimes be hard to distinguish this condition from scarlet fever, especially if a rash like the one associated with scarlet fever is present.

In a laboratory, A haemolyticum bacteria can be identified and distinguished from S pyogenes bacteria by its negative response to certain tests used to identify Streptococcus species and catalase, and its positive response to the reverse CAMP test. Moreover, severe upper respiratory infections can trigger symptoms similar to diphtheria. Such symptoms include the presence of a gray coating on the tonsil or above the windpipe. However, the inability of A haemolyticum bacteria to grow on tellurite, a substance used in lab tests, helps to distinguish it from the bacteria causing diphtheria, known as C diphtheriae.

What to expect with Arcanobacterium haemolyticum Infections

Pharyngitis caused by A haemolyticum usually clears up within 7 to 10 days. It’s uncommon to experience complications, and with the right antibiotics, full recovery is typical.

Possible Complications When Diagnosed with Arcanobacterium haemolyticum Infections

Though it’s unusual, there are some complications tied to the infection caused by A haemolyticum. These include Lemierre syndrome (a rare bacterial infection), brain abscesses, endocarditis (heart infection), and bacteremia (bloodstream infection). If there’s a delay in recognizing and treating these complications, it could lead to a persistent infection and other issues. This has a negative effect and could increase the rate of serious outcomes and even death, especially for patients who already have serious health conditions.

Preventing Arcanobacterium haemolyticum Infections

Taking steps to prevent disease spread is vital, particularly though strategies like regular handwashing, covering the mouth when coughing, avoiding sharing utensils, and practicing social distancing when not feeling well. Patients need to understand why these steps are important and how to carry them out. Early illness detection can help manage symptoms effectively, usually assisted by the proper selection of antibiotics.

When dealing with A haemolyticum infections, supportive care is key. This includes ensuring that the patient is drinking enough fluids, resting well and taking nonsteroidal anti-inflammatory drugs if required. These measures could help alleviate symptoms and facilitate faster recovery.