Everything you need to know about the bacterium Mycoplasma pneumonia in children and adults

Who is the Mycoplasma pneumonia bacterium?

The Mycoplasma family includes several different pathogens (organisms that can cause disease).
The important one among these is called Mycoplasma pneumonia.

What kind of infections does the bacterium Mycoplasma pneumonia cause in children and adults?

Let’s start with the fact that the infection can be asymptomatic, that is, it is possible that the person will not experience any symptoms whatsoever.
If symptoms do manifest, the list is endless and includes:
Sore throat – usually without exudates, and it is a mild disease, as opposed to Group A Streptococcus (more in the following link).
Ear infection – there have been reports about ear infections, but these are less common.
Upper respiratory tract infection – including a runny nose.
Lower respiratory tract infection – including bronchitis.
Pneumonia – we have a chapter about pneumonia in children on this website, where I explain about the two types of pneumonias:
a. Typical pneumonia – usually caused by the bacterium pneumococcus (streptococcus pneumonia)
b. Atypical pneumonia – usually caused by the bacteria we are talking about right here, Mycoplasma pneumonia.
Rash – lots of different types of rashes. Occurs in 10% of children who get Mycoplasma, see more about this below.
Other – pretty much everything has been described in the medical literature including cardiac involvement, brain involvement and in fact, involvement of all the different systems in the body.

Who is at higher risk of developing severe infection from this bacterium?

As usual, it is people (children and adults), who have underlying medical conditions including congenital or acquired immune deficiencies, respiratory illnesses, cardiac diseases and more.
In other words, people who are generally healthy will probably have a mild disease while people who have underlying medical conditions can develop quite a severe illness.

How does pneumonia caused by this bacterium manifest?

You know how when we think of pneumonia we usually think of a severe illness, that is possibly even fatal, with high fever and extreme sickness? Well, usually, in pneumonia caused by Mycoplasma, the symptoms are just a notch milder.
Fever – is usually low grade. Sometimes it is absent.
Cough – dry in the beginning, productive later on.
Headache and fatigue.
There are bilateral findings on lung auscultation and the child or adult will often have shortness of breath. Note, this is an important finding for a doctor, when examining a patient suspected to have Mycoplasma infection.
Keep in mind, that the above description is just a general description, and some people can develop severe respiratory disease.
In the absence of treatment, the symptoms, particularly the cough, will last 3-4 weeks and in healthy children and adults, they will resolve spontaneously.

What is the prevalence of this illness?

It is difficult to present an accurate estimate of the prevalence of this infection.
It tends to break out in different areas, so there are times when you will hear more about the infection than others.
Outbreaks have been described on city and country levels as well as at hospitals, military bases and camps.
It is well known that about 10% of children who will catch the bacteria will develop pneumonia. That means about 90% won’t.
Another important point is that pneumonia caused Mycoplasma is more common than any other pneumonia in children over the age of 5 and certainly in adults, as I mentioned in the chapter that discusses pneumonias in general. However, in children under the age of 5, this infection is not common at all.

Was there a recent outbreak in China and how does this outbreak affect the rest of the world?

A large number of pneumonia cases in children was reported in November 2023 in China, and the infections were suggested to have been caused by this bacterium.
Ever since, there have been reports from other parts of the world about rising numbers of infection due to this bacterium.
It is important to keep in mind that peaks of morbidity, or in other words outbreaks caused by this bacterium have been reported in the past and will be reported in the future, and so there is no need to be phased by reports that may or may not be reliable.
Morbidity should be followed and monitored, and outbreaks should be analyzed so that adequate guidelines can be released.

How is this bacterium transmitted?

This virus is transmitted through air droplets from one person to the other, usually from a symptomatic person to a healthy person. There is a study that found that about 30% of people within the same family will catch the bacteria after having all been with an infected family member.
The incubation period, or the time from exposure to the time when symptoms appear, ranges from 1-4 weeks, but it is usually 2-3 weeks.

How is this infection diagnosed?

It starts with clinical suspicion – a child over 5 years that presents with atypical pneumonia.
The history of illness will include prolonged symptoms involving cough, with or without fever.
The physical exam will reveal characteristic findings on auscultation of the lungs.
If labs are drawn, the inflammatory markers are usually not high, compared to typical pneumonia where the CRP is usually very high (if you don’t know what CRP is, read this article ASAP!).
A chest x-ray will reveal bilateral findings, both on the right and on the left side.

How is the diagnosis confirmed?

The diagnosis is confirmed with the help of both clinical findings, imaging, and isolation of the bacterium in the respiratory tract of the patient using the PCR technique (similarly to the technique used to test for COVID-19).

A few notes on this:
a. One can carry this bacterium in their respiratory tract for a long time following infection and they may even carry it when asymptomatic and therefore it is very important to have both clinical findings and a positive PCR test before you can confirm the diagnosis
b. This PCR test is not usually available in primary care settings, mostly in hospitals.
c. Antibody serology tests in the blood – this is a very inaccurate diagnostic method for Mycoplasma and should not be practiced.

What is the deal with the rash that appears following Mycoplasma pneumonia infections?

Mycoplasma pneumonia infection can cause lots of different types of rashes.
From a simple rash to a severe rash that requires hospitalization and aggressive treatment (Steven Johnson’s).
Sometimes patients are diagnosed with Mycoplasma pneumonia only after they present with the characteristic rash.

What is the treatment for this infection?

It is a little complicated.
In children who have no significant past medical history, and present at a primary care settings with lower respiratory tract infections, one can offer them the treatment that I will discuss below, but evidence supporting the efficacy of this treatment is lacking.
On the other hand, children who are hospitalized because of this infection must get treatment.
The treatment of choice is an antibiotic from the macrolide family such as azithromycin, erythromycin, or clarithromycin.
Antibiotics from the quinolone family are also adequate, especially in adults.
Penicillin and its derivates, such as amoxicillin, are not suitable antibiotics for treatment of this bacterium.

What is our biggest problem with this bacterium?

The problem is that the range of possible symptoms is very wide, in both children and adults, and I wouldn’t want all the children or adults who have been coughing for 4 days to receive antibiotics under this diagnosis.
Since the most accurate way to confirm this diagnosis is by performing a PCR test, which can only be done in hospital-based settings, it becomes really difficult to make this diagnosis in primary care settings and most people end up receiving antibiotics for it simply because of clinical suspicion.

What about the vaccine for pneumonia? Does it provide protection against Mycoplasma pneumonia?

No, it does not. There is no vaccine for Mycoplasma pneumonia.
The vaccine for pneumonia that is discussed thoroughly on this website in the link here, protects against a different antibiotic called pneumococcus (streptococcus pneumonia).

Are there any other important messages with regards to Mycoplasma pneumonia?

Yes. Keep in mind that this infection is not common in children under the age of 5, and therefore I am against the excessive use of azithromycin in this young age group.
When you stand, as a provider, in front of a child or an adult with suspected pneumonia, you have to think about what will actually do your patient good. Will it be penicillin, the antibiotic that is able to treat typical pneumonia or a macrolide, the antibiotics that is able to treat Mycoplasma pneumonia?
The doctor’s role is to gather all the signs and symptoms and the laboratory and x-ray findings and to make a decision.
Another important note – just like every other pathogen, the difficult cases that we hear of here and there, are just the tip of the iceberg of many cases that often go unnoticed and undiagnosed. So, try not to worry when you hear about patients with severe infections.
At the same time, just like for every other infectious disease, healthcare authorities should be alert, identify outbreaks promptly and take relevant measures to contain them.

Until then my friends, all the best!