Pasteurella Multocida

What is Pasteurella Multocida?

Pasteurella multocida is a bacterium most often found in animals like dogs and cats, and is typically associated with infections from their bites or scratches. Once introduced into the human body, this bacterium usually causes infection in the soft tissue – the layers of tissue beneath the skin, but above the bones. In some instances, especially in elderly people, those with weakened immune systems, or newborn babies, it can lead to serious health issues like blood infections (bacteremia), infections of the brain membrane (meningitis), or infection of the heart valves (endocarditis).

Most cases of P. multocida infections respond well to penicillin, an antibiotic, making this the first choice of treatment. However, in the rare cases where penicillin doesn’t work, other types of antibiotics such as cephalosporins, fluoroquinolones, or tetracyclines come into play.

What Causes Pasteurella Multocida?

Pasteurella multocida is a type of bacteria that typically causes infections in soft tissues like skin and muscles, usually after someone has been bitten or scratched by an animal. Though encounters with household pets like dogs and cats are the most common sources of this infection, wild creatures like rats, horses, and rabbits could also transmit it.

It’s important to note that the bacteria don’t always need to enter the body through a wound, as there’s evidence to suggest that you could also get a more serious infection in the bone or brain from simply being licked by an infected animal.

However, infections that spread inside the body, such as to the bloodstream, brain, or heart, are quite rare. These invasive infections almost always occur in individuals with weakened immune systems – these could include older people, newborns, and those with ongoing lung conditions.

Risk Factors and Frequency for Pasteurella Multocida

In the United States, about 300,000 people go to the emergency department every year due to animal scratches or bites. Most of these wounds end up infected with a bacteria known as Pasteurella multocida. Lots of animals naturally carry this bacteria in their mouth and upper respiratory tract. Cats are the most common carriers, with 70% to 90% of them hosting the bacteria, and dogs come next with a 20% to 50% carriage rate. Research has found that if you’re bitten by a dog, there’s a 50% chance the wound could get infected with Pasteurella, and if it’s a cat bite, the odds go up to 75%. Less often, people can get a Pasteurella infection even if they weren’t bitten or scratched, like from an animal lick, but these cases are rare.

Also, it’s rare to get a respiratory infection from Pasteurella unless you have a weak immune system or chronic lung disease. The bacteria can also cause serious infections such as meningitis and endocarditis, but these cases usually involve newborns, the elderly, or individuals with compromised immune systems.

Signs and Symptoms of Pasteurella Multocida

Pasteurella multocida is an infection often caused by an animal scratch or bite. It tends to develop rapidly, usually between 3 and 48 hours after injury. Swelling, redness, and tenderness at the site of injury are common signs of infection. Other symptoms might include fluid (bloody or pus-like) drainage and swollen local lymph nodes. In rare instances, the infection can lead to necrotizing fasciitis, which is characterized by excessive pain, swelling, and a cracking sound from the affected tissue.

Aside from the initial injury, some people may experience soft tissue infection that can potentially lead to bacteremia. Symptoms of bacteremia might include fever, rapid heartbeat, and low blood pressure. There could be complications like joint infection (septic arthritis) and bone infection (osteomyelitis) due to this type of bug.

Notably, joint infections don’t result directly from the injury, and the affected area is usually farther from the initial skin penetration. Those with health conditions like diabetes, alcoholism, or chronic corticosteroid use, as well as those with a previous history of joint damage due to replacement or degenerative disease, are more susceptible to joint infection. In most cases, the knee joint is affected.

Strangely, one-third of patients with this joint infection due to Pasteurella multocida don’t recall a scratch or bite injury. Therefore, it’s crucial for doctors to get a detailed history of potential animal exposure. People with deep wounds, particularly from cat bites, may also develop bone infection. Wounds penetrating the outer layer of bone are more prone to this complication, but direct contact with the germs is not necessary. Soft tissue infection can expand locally and then reach the bone. Cat bites on the hand especially carry a high risk of joint and bone infection happening together.

Respiratory or severe infections such as heart valve infection (endocarditis) and brain infection (meningitis) are also possible with this bug. However, these do not have specific features that help diagnose them conclusively. If patients with unexplained symptoms have been in contact with animals or are immunocompromised, doctors should consider Pasteurella multocida infection as a potential cause.

Testing for Pasteurella Multocida

If you’ve been bitten or scratched by an animal, your doctor might recommend an X-ray of the wounded area. This X-ray can help the doctor see if your bones are fractured, if anything has been left behind in the wound, or if there are any signs of osteomyelitis or a necrotizing infection. Osteomyelitis is an infection in a bone, and a necrotizing infection is a serious condition that causes body tissues to die.

Your doctor may also ask for a complete blood count test, which is a common and simple test that evaluates your general health and detects a whole range of disorders, including infections.

You could also have a test called an Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP). Both of these tests are used to determine if your body is having an inflammation response, signaling something is wrong, like osteomyelitis.

A culture of your wound could be done as well to see if there is an infection present. If an infection appears to have spread beyond the wound site, a blood culture test could be ordered. If, upon examination, your doctor thinks you may have osteomyelitis, an MRI scan may be taken for a closer look.

If there’s a chance you could have septic arthritis – a painful infection in a joint – a procedure called arthrocentesis may be performed for confirmation. This procedure involves taking fluid from the joint to examine for the cause of the infection.

If you’re having trouble breathing, they might take a culture of your sputum – this is mucus that’s coughed up from your lungs – to help them figure out what’s wrong. If you’re showing signs of meningitis, which is a serious infection of the fluid around your brain and spinal cord, you may undergo a procedure called lumbar puncture. This test helps in getting the cerebrospinal fluid (CSF) which is sent for a test to identify the cause of the condition.

The most recommended way of growing a bacteria named Pasteurella multocida is on a medium called 5% sheep’s blood agar at a temperature of 37 degrees Celsius. This bacteria is gram-negative, non-moving, and can survive both with and without oxygen. These bacteria are typically sensitive to penicillin and will test positive for several chemicals used to identify them, such as catalase, oxidase, indole, sucrose,and decarboxylate ornithine.

Treatment Options for Pasteurella Multocida

If you’ve been bitten or scratched by an animal, it’s important that your doctor first make sure you are stable overall. This includes checking your airway, your breathing, and your blood flow. Once you are stable, your doctor will then clean your wound with a lot of sterile water. This might be done under local anesthesia (numbing medication) to avoid pain. You might also have an x-ray to check for any fractures (broken bones) or to see if anything got stuck in your wound.

If needed, your doctor might stitch up your wound. However, this can increase the risk of infection, so it’s usually avoided if possible. When stitches are necessary, they’ll leave a bit of space open to allow the wound to drain. You might also receive a vaccine for tetanus if needed, and you should consider getting treatment against rabies for any animal-related injuries.

Antibiotics aren’t always recommended for animal bites or scratches. Whether you get antibiotics may depend on factors such as your overall health and the severity of your injury. For instance, people with health conditions that weaken their immune system, like diabetes or cirrhosis, may be at higher risk and require antibiotics. Also, certain types of injuries—e.g., those to the hand, face, or genitals, deep or large wounds, or wounds near a bone or artificial joint—may be more severe and require antibiotics.

If you don’t have any complications, your doctor may suggest you go home and keep a close eye on your wound. If you’re given antibiotics, you should take them orally for about 3 to 5 days. If you notice signs of infection, like swelling or redness, you should go back to see your doctor.

Complications, such as infection spreading to other parts of your body or not responding to oral antibiotics, could warrant stronger treatment. In that case, your doctor might recommend intravenous (i.e. into your vein) antibiotics until your infection begins to improve. Then, you can switch to oral antibiotics for another 5-14 days.

In some circumstances, surgical intervention might be necessary, particularly for wounds with dead tissue, abscess (pockets of pus), or if you show signs of a severe infection. If you require wound cleaning, care should be taken to send tissue samples for laboratory testing. If feasible, your wound might not be stitched up immediately after the surgery to allow for drainage. Under normal circumstances, if you need minor wound cleaning, you can be sent home with oral antibiotics for 5-14 days, which can be extended if the infection takes a long time to get better. If you have a more complicated infection, such as bone or joint inflammation due to the infection, you might need a prolonged course of antibiotics.

The above management plan covers the treatment of pasteurella infection, which typically occurs when someone gets bitten by a cat or dog. For this particular infection, the first choice for antibiotics is usually oral amoxicillin-clavulanate or an equivalent. If you are started on an IV antibiotic, your doctor could choose a different combination of medications. It’s important to remember that each treatment plan is tailored to the patient’s condition and the results of their laboratory tests.

While dog and cat bites are most commonly infected by a bacteria called Pasteurella multocida, there are several other germs that can also cause infections. These include:

Bartonella henselae, often associated with cat scratch disease
Clostridium tetani, the bacteria that causes tetanus
Staphylococcus aureus, a common cause of skin infections
Rabies lyssavirus, the virus that causes rabies

Therefore, it’s essential to clean and monitor animal bites and scratches carefully for signs of infection.

What to expect with Pasteurella Multocida

Infections related to Pasteurella multocida, a type of bacteria, usually aren’t very problematic and can be resolved with the right treatment. Yet, when these infections show up on the hand, they can have more severe outcomes due to a higher chance of complications. Long-term health problems from these complications may include tenosynovitis (inflammation of the sheath that surrounds a tendon), osteomyelitis (infection in the bone), and septic arthritis (infection in the joint).

In more serious cases, where the infection causes conditions like bacteremia (bacteria in the blood), meningitis (inflammation of the protective membranes covering the brain and spinal cord), and endocarditis (inflammation of the heart’s inner lining), the situation significantly worsens. The mortality rate in such serious conditions is high, ranging from 25% to 30%.

Possible Complications When Diagnosed with Pasteurella Multocida

If an infected animal bite is not quickly treated, it can lead to some severe complications. In extreme conditions, diseases that affect the whole body might develop, including bacteremia (bacteria entering the bloodstream), endocarditis (inflammation of the heart’s inner lining), and meningitis (inflammation of the brain and spinal cord membranes). Other complications that are localized or affect a specific area include pus-filled sores, septic arthritis (joint infection), bone infection, and inflammation of the tendon sheath. The hand is most commonly affected by these localized complications.

Potentially Severe Consequences:

Bacteremia (bacteria in bloodstream)
Endocarditis (heart’s inner lining inflammation)
Meningitis (brain and spinal cord membranes inflammation)
Abscess formation (pus-filled sores)
Septic arthritis (joint infection)
Osteomyelitis (bone infection)
Tenosynovitis (inflammation of the tendon sheath)
Primarily affects hands

Preventing Pasteurella Multocida

If you are classified as a high-risk individual or if you’ve gotten a serious injury from an animal bite or scratch, it’s essential you see a doctor right away. Even if you are a low-risk individual, you should still seek medical help if you notice signs of an infection developing after an injury.

‘High-risk’ people usually have health-related issues that might make it harder for them to fight off infections or heal properly. This includes people with weaker immune systems, such as patients with diabetes, no spleen function (asplenia), or liver disease (cirrhosis). Other high-risk cases could include patients with degenerative joint disease or having a joint replacement prosthetic.

Injuries are classified as ‘high-risk’ when they are serious or occur in sensitive areas. Some examples of these include injuries to the hand, face, or genitals, deep puncture wounds or long cuts (which are more common in cat bites), wounds with associated crushing injury (more common in dog bites), injuries that needed surgical repair or stitches, and injuries near the bone or a joint, especially if it’s near a prosthetic joint.

Frequently asked questions

The prognosis for Pasteurella multocida infections is generally good, as most cases respond well to treatment with penicillin. However, in rare cases where penicillin is not effective, other types of antibiotics such as cephalosporins, fluoroquinolones, or tetracyclines can be used. In more serious cases, where the infection causes conditions like bacteremia, meningitis, or endocarditis, the prognosis is worse, with a mortality rate ranging from 25% to 30%.

Pasteurella multocida can be acquired through animal bites or scratches, as well as through being licked by an infected animal. It can also be transmitted through contact with the germs from an infected animal, even without a visible wound.

Signs and symptoms of Pasteurella multocida infection include: - Swelling, redness, and tenderness at the site of injury, which usually develops rapidly between 3 and 48 hours after an animal scratch or bite. - Fluid drainage (bloody or pus-like) from the site of injury. - Swollen local lymph nodes. - In rare cases, the infection can lead to necrotizing fasciitis, characterized by excessive pain, swelling, and a cracking sound from the affected tissue. - Some people may experience soft tissue infection that can potentially lead to bacteremia, which is indicated by symptoms such as fever, rapid heartbeat, and low blood pressure. - Complications like joint infection (septic arthritis) and bone infection (osteomyelitis) can occur due to this infection. - Joint infections usually do not result directly from the injury and are more common in individuals with health conditions like diabetes, alcoholism, chronic corticosteroid use, or previous joint damage. - Strangely, one-third of patients with joint infection due to Pasteurella multocida do not recall a scratch or bite injury, so a detailed history of potential animal exposure is crucial for diagnosis. - Deep wounds, particularly from cat bites, can lead to bone infection. - Respiratory or severe infections such as endocarditis (heart valve infection) and meningitis (brain infection) are also possible with Pasteurella multocida, especially in individuals who have been in contact with animals or are immunocompromised. However, these infections do not have specific features for conclusive diagnosis.

To properly diagnose Pasteurella multocida infection, the following tests may be ordered by a doctor: 1. Culture of the wound: This test is done to see if there is an infection present. 2. Blood culture: If the infection appears to have spread beyond the wound site, a blood culture test may be ordered. 3. Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP): These tests are used to determine if the body is having an inflammation response, which can indicate osteomyelitis. 4. X-ray: An X-ray of the wounded area may be recommended to check for fractures or if anything has been left behind in the wound. 5. MRI scan: If the doctor suspects osteomyelitis, an MRI scan may be taken for a closer look. 6. Arthrocentesis: If there is a chance of septic arthritis, a procedure called arthrocentesis may be performed to confirm the infection. 7. Sputum culture: If the patient is experiencing trouble breathing, a culture of the sputum (mucus coughed up from the lungs) may be taken to determine the cause. 8. Lumbar puncture: If signs of meningitis are present, a lumbar puncture may be performed to obtain cerebrospinal fluid (CSF) for testing. It's important to note that the specific tests ordered may vary depending on the individual patient's condition and symptoms.

The other conditions that a doctor needs to rule out when diagnosing Pasteurella multocida are: - Fractured bones - Presence of foreign objects in the wound - Osteomyelitis (infection in a bone) - Necrotizing infection (serious condition causing tissue death) - Septic arthritis (painful infection in a joint) - Meningitis (infection of the brain membrane) - Infection of the heart valves (endocarditis) - Blood infections (bacteremia) - Other infections caused by bacteria such as Bartonella henselae, Clostridium tetani, Staphylococcus aureus, or viruses such as Rabies lyssavirus.

When treating Pasteurella Multocida, there can be potential side effects and complications. These include: - Bacteremia: Bacteria entering the bloodstream. - Endocarditis: Inflammation of the heart's inner lining. - Meningitis: Inflammation of the brain and spinal cord membranes. - Abscess formation: Pus-filled sores. - Septic arthritis: Joint infection. - Osteomyelitis: Bone infection. - Tenosynovitis: Inflammation of the tendon sheath. - These complications primarily affect the hands.

You should see a doctor, preferably a healthcare professional with expertise in infectious diseases or a primary care physician.

Pasteurella multocida is quite common, with about 300,000 people in the United States going to the emergency department every year due to animal scratches or bites that end up infected with this bacteria.

Pasteurella multocida is typically treated with antibiotics. The first choice for antibiotics is usually oral amoxicillin-clavulanate or an equivalent. In some cases, if the infection is more severe or not responding to oral antibiotics, intravenous antibiotics may be recommended. The specific treatment plan will depend on the patient's condition and the results of their laboratory tests.

Pasteurella multocida is a bacterium most often found in animals like dogs and cats, and is typically associated with infections from their bites or scratches.

Antibiotics Bacterial Infections Infectious Disease Skin and Soft Tissue Infections