“Infections with the bacteria that causes walking pneumonia have risen significantly this year, particularly among young children.”
Centers for Disease Control and Prevention
“I lost a sister to pneumonia, when she was 2 years old. She died at home, not in a hospital, where maybe her life could have been saved.”
Mazie Hirono, U.S. Senator (Hawaii)
In the past few weeks, the Centers for Disease Control and Prevention (CDC) has issued a rash of reports about a spike in cases of “walking pneumonia”—a lung infection caused by the bacterium Mycoplasma pneumoniae. (See, “Mycoplasma Pneumoniae Infections Have Been Increasing,” CDC, October 18, 2024; “Cases of walking pneumonia are surging in kids this year, CDC reports,” CNN, October 25, 2024; “CDC Warns of Unusual Rise in Walking Pneumonia Cases,” New York Times, October 29, 2024). In this week’s Germ Gems post, I provide a brief overview of “walking pneumonia” as well as other pneumonias, with the goal of providing guidance on what to do should you develop a respiratory tract infection that could be pneumonia.
What is “walking pneumonia?” “Walking pneumonia” is a non-medical term that refers to a relatively mild lower respiratory tract (lung) infection caused by the bacterium, Mycoplasma pneumoniae. This bacterium lacks a cell wall and resides intracellularly in the respiratory tract of the human host. Although a related bacterium infects other animals, M. pneumoniae is principally a pathogen of humans and is spread by airborne droplets through close person-to-person contact via coughing or sneezing.
M. pneumoniae infections are usually mild; many present as a “chest cold.” Symptoms appear slowly one to three weeks after exposure and include sore throat, dry cough, headache, fever, and fatigue. M. pneumoniae, however, can also infect the lung(s) thereby causing pneumonia. But because symptoms are usually mild, people may not stay home or in bed, hence the name “walking pneumonia.”
While anyone can acquire M. pneumoniae, children and young adults are at highest risk of infection. If you or anyone in your family develops what seems like a cold that lasts longer than seven to ten days and is not getting better, you could have walking pneumonia. See your doctor or health care professional to confirm the diagnosis and treat the infection. Antibiotics are an effective treatment for M. pneumoniae infections. The best antibiotics for this purpose are azithromycin, clarithromycin, or doxycycline.
Why are cases of “walking pneumonia” on the rise? It is suggested that with the waning of COVID-19, the use of masks was reduced and the restrictions on social gatherings were lifted allowing more close contact between children which in turn facilitated M. pneumoniae infections. It may well be that in the aftermath of COVID, we have become lax in following basic hygiene practices when we have a cold such as covering our coughs, washing our hands correctly, and wearing a mask when are around others. That said, no one knows why cases of “walking pneumonia” are on the rise.
“Typical pneumonia” and “atypical pneumonia.” “Typical pneumonia” is a lung infection caused by one of the pathogens “typically” associated with the disease. These include viruses, fungi and virulent bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Legionella pneumophila.
Typical pneumonia can be very serious and even deadly. It presents with a sudden onset of fever, chills, chest pain, and productive cough. In older adults and children, the symptoms are generally more severe. If you or your loved one develops a severe cough—especially one productive of yellow or green sputum, shortness of breath, lightheadedness, or confusion, see your health care professional immediately.
Treatment for typical pneumonia will depend on the type of pneumonia you have, that is, what pathogen caused the pneumonia. If you have a bacterial pneumonia, it can usually be treated with antibiotics at home on an out-patient basis. But if you have a severe case of pneumonia, you may need to be hospitalized.
“Atypical pneumonia,” a medical term introduced in the 1930s, refers to any type of pneumonia that is not caused by one of the pathogens commonly (“typically”) associated with the disease. Atypical pneumonia is also known as “walking pneumonia.” In addition to M. pneumoniae, however, other bacteria, such as Chlamydia pneumoniae, and a variety of viruses (respiratory syncytial virus [RSV], influenza A, SARS, MERS, and SARS-CoV2) can also cause atypical pneumonia.
Atypical pneumonia tends to have milder symptoms than typical pneumonia and is rarely fatal. All bacterial causes of atypical pneumonia, including M. pneumoniae, should be treated with antibiotics.
What next? According to the CDC, there are roughly two million M. pneumoniae infections per year in the U.S. This is likely an underestimate. Many M. pneumoniae cases aren’t diagnosed because of inadequate testing methods—methods that fall short of gene-based (multiplex) assays. (See, “Underdiagnosing of Mycoplasma pneumoniae infections as revealed by use of a respiratory multiplex PCR panel,” Diagnostic Microbiology and Infectious Diseases, 2016). While these tests are often underutilized—perhaps driven by a desire to curb costs, I believe they should be used more widely.
These multiplex assays are rapid, highly sensitive and accurate. They can screen for multiple microbes simultaneously including bacteria (M. pneumoniae, H. influenzae, C. pneumoniae, Legionella, Klebsiella pneumoniae, S. aureus, S. pneumoniae, and Pseudomonas aeruginosa), viruses (adenovirus, influenza A and B, RSV, and enteroviruses), and yeasts (Candida species). As the authors of the above-cited article stated: “Multiplex syndromic testing can overcome underdiagnosing of important respiratory pathogens thus allowing improved targeted therapy or application of appropriate infection control measures.” It could potentially affect patient outcomes. If we want to make inroads in the management of both “atypical” and “typical” pneumonias, perhaps we could start by routinely using these multiplex assays.
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