Coughs that linger after a cold or sinus problem cause constant disruption in the home, school, and workplace.
Often, these dry, nonproductive coughs become increasingly troublesome although other symptoms – fever,
congestion, and fatigue – resolved days or weeks ago. This stubborn cough persists for weeks, and plagues its
victim and the victim’s family night and day. The diagnosis might be a common, but overlooked cause of
lingering cough: atypical pneumonia caused by mycoplasma. Mycoplasma – pleomorphic bacteria that lack a
cell wall – are the smallest and simplest self-replicating organisms known to humans. They probably evolved
from gram-positive, walled eubacteria by degenerative evolution. Smaller than amoebas, these 0.1-micrometer
organisms grow and reproduce slowly and require no oxygen or host cell. They also change shapes
asymmetrically, appearing as long, thin filaments, tiny spheres, or branches. Scientists have identified more
than 100 mycoplasma species. Fifteen species are known to live in humans, most as normal symbiotic flora.
Mycoplasma pneumoniae, previously called “walking pneumonia,” is pathogenic in humans. Mycoplasma
pneumoniae glides freely and uses its specialized filamentous tips to burrow between cilia within the respiratory
epithelium, causing the respiratory epithelial cells to slough. It also produces hydrogen peroxide, which causes
initial cell disruption in the respiratory tract and damages erythrocyte membranes. Researchers have
determined that more than 40% of infants younger than 1 year old have had a mycoplasma infection. By age 5,
approximately 65% of children have been infected. Nearly all adults have been infected at least once, often
repeatedly. Mycoplasma pneumonia usually affects people younger than 40 years of age. The highest
incidence is found in the 5- to 9-year age group. The risk of contracting mycoplasma pneumonia is greatest for
people who live or work in crowded areas, such as daycare facilities, schools, homeless shelters, long-term
care units, and military and prison environments. However, many people who develop mycoplasma infections
have no identifiable risk factor. Most mycoplasma infections cause mild to moderate clinical symptoms, but the
infection incubates over 3 weeks and can last weeks without treatment. This infection cannot be diagnosed
based on symptoms alone; laboratory testing is essential. Infection can also cause ear infections, sinus
infections, bronchitis, croup, severe sore throats, infectious asthma, and 1 type of the common cold. When
mycoplasma infects children, about 25% of them develop nausea, vomiting, or diarrhea.
Which of the following is NOT true about mycoplasma infection?
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