What is Kingella Kingae?
Kingella kingae used to be thought of as a rare bacteria until recent improvements in diagnostic methods. It’s now recognized as a significant cause of blood and bone infections in children aged between 6 to 48 months. This bacterium is one of the causes of disease outbreaks in daycare centers in the United States and other countries. Although Kingella kingae naturally resides in the throat lining of children between 6 to 48 months, it can enter the bloodstream through damaged tissues and cause infections in the body.
The infections caused by K. kingae usually have mild symptoms, except in cases of endocarditis – a condition that affects the heart lining – and osteoarticular infections, which impact the bones and joints. It’s important to be aware of this bacterium and the potential health issues it can cause in children.
What Causes Kingella Kingae?
K. kingae is a type of bacteria that falls under the Neisseriaceae family. Despite being tough to grow in a laboratory (which is what we mean by ‘fastidious’), it can live both with and without oxygen, marking it as a ‘facultative anaerobic’ organism. When we say it’s ‘gram-negative’, it simply means it doesn’t hold the violet stain used in Gram staining, a method to identify bacteria. It’s ‘coccobacillus’ because of its shape that is somewhat round and somewhat rod-like.
This bacteria can break down red blood cells causing a faint ring of hemolysis (damage to red blood cells). K. kingae doesn’t move on its own and it doesn’t produce spores (a kind of ‘seed’ that bacteria use to survive in harsh conditions).
All varieties of K. kingae interact strongly with a reagent called ‘oxidase’, but they don’t react with substances such as catalase, indole, and urease. This type of bacteria grows on blood agar, chocolate agar, and GC-based media (all of these are substances in a petri dish that provide nutrients for bacteria to grow) but won’t grow on ones called MacConkey or Krigler agar.
Lastly, K. kingae can exhibit different growth patterns. It can spread across the growth medium, generally with fringes, or the colony can grow tall and dome-shaped without any fringe.
Risk Factors and Frequency for Kingella Kingae
Reports indicate a rising number of K. kingae infections, a type of bacteria, in the US, Western Europe, and Israel; however, the global illness’s full impact is still unclear. This infection primarily affects young children, particularly those under four years old. The rate at which this bacteria appears in kids aged 1 to 4 ranges from 10 to 28%. In contrast, fewer than 1% of infants 0 to 6 months old and adults carry this bacteria. Males are believed to be more often affected than females. Furthermore, factors like attending daycare are linked to a higher risk of getting a serious K. kingae infection.
- The number of K. kingae infections is rising in the US, Western Europe, and Israel.
- The global impact of this disease is still not fully understood.
- The infection mostly affects children under four years old.
- The rate of this bacteria in children aged 1 to 4 years is 10 to 28%.
- The bacteria’s rate in infants 0 to 6 months old and adults is less than 1%.
- Males are more likely to get this infection than females.
- Factors like attending daycare can increase the chance of getting this infection.
Signs and Symptoms of Kingella Kingae
K. kingae is an infection that most frequently occurs in healthy children under the age of four or in immunocompromised older children and adults. The symptoms typically include mild fever, back pain, and night sweats especially in more serious cases, and may be accompanied by symptoms related to the upper respiratory tract or diarrhea.
This particular infection can affect different body systems which can include:
- The skeletal system: It is the most common cause of skeletal infections in children under four years old. The symptoms can appear slowly and may only be noticeable in the second week of infection.
- Septic arthritis: This is a common form of disease caused by K. kingae. It mostly affects the lower body and often the knee. There may also be more than one joint affected. Symptoms can include localized pain, swelling, warmth, and immobility of the joint.
- Osteomyelitis: This tends to affect the long bones of the lower extremity and often presents in a less acute form. It can affect bones like the clavicle, sternum, and the calcaneus.
- Spondylodiscitis: This is an infection of the disk spaces and adjacent vertebrae, causing difficulties in walking or sitting. Children may also experience back pain, stiffness, and abnormal gait.
- Bacteremia: K. kingae may be found in the blood without any other infection, or it may occur alongside other infections. Symptoms may include a mild fever and a rash similar to that of meningococcal or gonococcal infections.
- Soft-tissue infections: This can include a wide range of infections such as cellulitis, bursitis, tenosynovitis, and dactylitis, and abscesses in different locations.
- Endocarditis: K. kingae is a leading cause of endocarditis in children. Patients may experience heart-related symptoms like shock, heart failure, or complications due to embolism in the brain, bones, and lungs.
- Meningitis: K. kingae could also lead to meningitis due to the spread of the infection from the blood to the brain or from septic embolism from the heart.
- Other symptoms: K. kingae can cause other infections that may affect the eyes like keratitis and endophthalmitis, urinary tract infections, and pericarditis.
Testing for Kingella Kingae
Doctors can use two main types of tests to detect the organisms responsible for certain diseases: microbiological cultures and nucleic acid amplification assays. The microbiological culture tests involve using things such as blood culture vials and blood agar which allow the bacteria to grow. Doctors can then study these growths to identify the bacteria. Although, this method can sometimes yield inconsistent findings. The nucleic acid amplification test, which is commonly used in advanced countries, is quicker and tends to be more accurate.
Besides these, doctors may also order some more tests. These include complete blood counts, a test to check the level of C-reactive protein (CRP which is a substance produced by the liver in response to inflammation) in the blood, and radiological investigations like X-rays, CT scans, MRIs, etc. These tests can provide more information about the disease and help the doctors arrive at a more accurate diagnosis.
Additionally, in the case of children with invasive diseases (illnesses that spread to surrounding tissues), a transthoracic echocardiogram is generally recommended. This is a type of an ultrasound that looks at how the heart’s functioning, the reason it’s recommended is due to concerns about a serious heart condition known as endocarditis (an infection of the inner lining of the heart chambers and valves).
Treatment Options for Kingella Kingae
In order to manage serious bacterial infections, doctors often start treatment with strong antibiotics given through an IV while waiting for culture results. These antibiotics are typically broad-spectrum, meaning they can kill a wide range of bacteria. Once the specific bacteria causing the infection is identified (such as K. kingae), the treatment can be adjusted accordingly. This might include switching to a different antibiotic like ampicillin if the bacteria are not resistant, or a combination of ampicillin and sulbactam if the bacteria are found to be resistant. Other antibiotics like Ccefuroxime and ceftriaxone may also be used.
When it comes to illnesses like septic arthritis (an infection in the joint), osteomyelitis (an infection in the bone), and spondylodiscitis (an infection in the spine), the length of time on antibiotics can vary. For septic arthritis, the recommended treatment is usually 2 to 3 weeks of antibiotics, which start intravenously (through an IV) and then switch to oral medication. Traditional treatment for osteomyelitis can last anywhere from 3 weeks to 6 months, while conventional therapy for spondylodiscitis typically ranges from 3 to 12 weeks.
However, some modern treatment strategies may shorten the length of antibiotic therapy, promote an earlier switch from IV to oral medication, and use a blood test called CRP to track the body’s response to treatment. Generally, if the treatment is working and the level of CRP in the blood drops to less than 20mg/l, the doctor may switch you to oral antibiotics and even decide when to stop the treatment. In many cases, infections can be resolved with antibiotics alone, and there is no need for additional procedures like repeated aspirations or surgical washouts.
What else can Kingella Kingae be?
Some common infections that doctors need to be aware of include:
- Haemophilus influenza type b
- Neisseria meningitidis
- HACEK infections
- Streptococcus pneumonia
- Staphylococcal septic arthritis
What to expect with Kingella Kingae
Most infections caused by the bacteria Kingella kingae are not severe if they are caught and treated quickly. Most types of this bacteria are vulnerable to antibiotics commonly given to children, except for one type that’s resistant to beta-lactamase, a type of antibiotic. Kids usually make a full recovery from infections of the bones and joints without any complications.
Although an abscess, or a pocket of pus, can sometimes develop in the spine due to Kingella spondylodiscitis, an infection in the spine, this condition usually responds well to antibiotics. It’s also rare for these infections to cause complications like narrowing of the spaces between the spinal disks.
However, Kingella kingae can also cause endocarditis, an infection of the heart’s inner lining, which can be life-threatening. This condition has a mortality rate close to 20%. Therefore, immediate and aggressive treatment is often necessary for a successful recovery.
Possible Complications When Diagnosed with Kingella Kingae
As mentioned earlier, complications can involve bone and joint diseases and inflammation of the heart’s inner lining.
Potential Complications:
- Bone and joint diseases
- Inflammation of the heart’s inner lining
Preventing Kingella Kingae
An infection from the Kingella bacteria may show up with mild symptoms that aren’t immediately obvious. If children are running a fever and also show signs that could be linked to this type of infection, they should be examined to rule out the possibility of Kingella infection. If your child is between 6 months and 4 years old and develops a fever along with sudden joint issues, a rash, or serious heart problems, you should seek medical help immediately. This will ensure they’re properly evaluated and receive needed treatment.
