COXIELLA BURNETII: CHARACTERISTICS, MORPHOLOGY, HABITAT, LIFE CYCLE - BIOLOGY - 2025

Coxiella burnetii is a gram negative bacterium that affects the organism of certain animals, causing a pathology known as Q fever. Its name is due to the researcher Cornelius Phillip, who in 1948 proposed to name it Coxiella burnetii in honor of Herald Rea Cox and Macfarlane Burnet, who worked hard on his study, specifically on his identification and the effect it had on his guests.

In general, Q fever is not a life-threatening illness. However, there are people in whom it can affect some important organs such as the liver, lungs and heart, causing damage that can become irreversible.

Coxiella burnetii cells inside their host. Source: National Institutes of Health (NIH) / Public domain

The bacteria is highly infectious, especially if its particles are inhaled. So much so that specialists consider that it can be used in bioterrorism attacks. Because of this, it has been classified in category B of potential bioterrorism agents.

Characteristics of

It is gram negative

By inhalation

The most common way of transmission of this bacteria is inhalation. This occurs because the bacteria are usually found in the milk of infected animals, feces, urine and even more so in the fragments of the placenta, as well as in the umbilical cord.

When a person inhales particles of the bacteria, they will most likely end up developing Q fever, since the virulence of this microorganism is high.

Likewise, scientists specializing in the behavior of this bacterium have determined that it is capable of infecting certain microorganisms such as amoebae, which are sometimes found in air conditioning systems. Unquestionably, this is one of the ways in which humans could inhale bacterial particles.

By action of a vector

This route of contagion ranks second in terms of frequency. As is well known, the tick is one of the animals that plays an important role in the life cycle of Coxiella burnetii.

When the mite bites an animal that is infected, it acquires the bacteria and later, when it bites a healthy animal, it inoculates it.

However, far from what you might think, infection in humans from a tick bite is rare.

By direct human - human contact

Transmission from an infected person to a healthy one is truly exceptional. In the medical literature there are some cases of contagion through blood products and also through unprotected sexual relations. The latter is possible because in various investigations bacterial particles have been found in body fluids such as semen.

By ingesting infected food

It is important to remember that in infected animals the bacteria can be found in milk. Due to this, many affirm that the ingestion of food from infected animals could be a valid route of infection.

However, there are no reliable and truthful records through which the contagion of Coxiella burnetii by the ingestion of cheese or dairy products is evidenced.

Symptoms

Most people with Q fever remain asymptomatic, that is, they do not have any symptoms. However, there are also others that do manifest an acute clinical picture, which can appear suddenly. Among the symptoms can be found:

• Fever, which is moderate at first, but as time goes on it can even reach 41 ° C (105 ° F)
• Shaking chills
• Tiredness, which can be extreme
• Intense headache
• Respiratory symptoms such as cough and pleuritic chest pain
• Digestive symptoms such as diarrhea, vomiting, and nausea.
• Hepatomegaly

It can happen that the infection becomes chronic, the patient can develop conditions such as endocarditis, kidney failure and even hepatitis.

Treatment

Taking into account that Q fever is caused by bacteria, the treatment prescribed by doctors is with antibiotics. The antibiotic of choice to treat this infection is doxycycline.

However, the duration of treatment depends on whether it is acute or chronic. In the first case, treatment should be administered for 2 to 3 weeks. On the contrary, in the case of chronic infections, treatment can last up to 18 months.

Likewise, in the case of complications that involve other structures such as the organs of the central nervous system or the liver, other types of medications must also be administered.

In the case of people with liver problems, they should also take prednisone, while people who suffer from meningoencephalitis, should also take fluoroquinolone therapy.

Surgical treatment may also be necessary for patients suffering from endocarditis caused by Cloxiella burnetii infection. They may need surgery to modify or change the atrioventricular valves.

Chemical tests to detect it

Diagnosis of Coxiella burnetii infection is possible through several procedures. The following are the most used by medical professionals.

Indirect immunofluorescence of infected tissue

This is the technique most used by specialists to diagnose Coxiella burnetii infection. This test is basically used to determine the presence of antibodies against the bacteria.

The procedure for this test is as follows:

• In the first place, the rheumatoid factor is administered, in order to eliminate the chances of a false positive regarding the detection of IgM immunoglobulins.
• Next, antigens of the Coxiella burnetii bacteria are placed on a slide.
• Subsequently, a sample of the tissue that is considered to be infected is placed on this substrate. If the bacterium is present in the tissue sample, antibodies against it have been formed there and, consequently, the well-known "antigen-antibody" complex is formed.
• Immediately, an anti-human immunoglobulin conjugated to a compound known as fluoroform is added to this. This immunoglobulin reacts with the antibody of the antigen-antibody complex that was initially formed.
• Finally this is seen with an immunofluorescence microscope and there the diagnosis is confirmed.

Polymerase chain reaction (PCR)

The polymerase chain reaction is a technique that aims to amplify small pieces of DNA. This technique can be applied to serum or samples collected through biopsy, as well as to serum or blood.

Although this is a highly sensitive test, a negative result does not necessarily exclude the diagnosis of a Coxiella burnetii infection. For some specialists, this is a complementary test, since the determining test is immunofluorescence.

Other blood tests

It is important to mention that there are some abnormalities that are evident in a complete blood count that can give the specialist doctor an orientation about the diagnosis of Cloxiella burnetii infection.

A high percentage of people who are infected by the bacteria have a condition known as leukocytosis. This is defined as an increase in the levels of white blood cells (leukocytes) in the blood.

Likewise, the elevation of certain enzymes such as aspartate aminotransferase, alkaline phosphatase and alanine transaminase indicate that the patient could be infected with Coxiella burnetii.

In this sense, when the doctor detects these anomalies, added to the clinical picture of the patient, he may suspect an infection by the aforementioned bacteria. If this is the case, you should order a test with a definitive result, such as immunofluorescence.

References

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