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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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