Taxonomy and Microbiology The clinically important genital mycoplasmas— Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum, and Ureaplasma parvum —belong to the Mollicutes class and Mycoplasmataceae family of bacteria. Mycoplasma spp. and Ureaplasma spp. are the only two genera in this family.…
Reviewed for currency January, 2020 The concept of atypical pneumonia antedated the start of the antibiotic era. At least as early as World War I it was recognized that “…in the larger number of cases observed in the [military] camps…
Chlamydiae are obligate intracellular bacterial pathogens whose entry into mucosal epithelial cells is necessary for intracellular survival and subsequent growth. Chlamydiae cause a variety of diseases in animal species at virtually all phylogenic levels, from amphibians and reptiles to birds…
Reviewed for currency January 14, 2021 Psittacosis is a systemic infection that frequently causes pneumonia. Its relationship to bird exposure has been known for more than 100 years. In 1879, Ritter studied an outbreak in Switzerland and called it pneumotyphus.…
Revised August 2, 2021 Chlamydia trachomatis imposes a tremendous burden on human health because it is one of the most common causes of bacterial infection. Worldwide in 2011, an estimated 21 million people had active trachoma, which is an ocular…
Reviewed for currency February, 2020 Prions are the transmissible agents of a class of neurodegenerative diseases of humans and other mammals. Prions differ from other infectious agents in that they contain no information-bearing nucleic acid. Rather, they are composed mainly,…
Revised March 29, 2022 Hepatitis E virus (HEV) is a ribonucleic acid (RNA) virus that causes a viral hepatitis that is indistinguishable from other forms of viral hepatitis. The World Health Organization (WHO) estimates a global incidence of 20 million…
Reviewed for currency February, 2020 Viral gastroenteritis is caused largely by noroviruses and sapoviruses (see Chapter 176 ) and by rotaviruses (see Chapter 150 ). Astroviruses are also established as important causes of gastroenteritis, albeit substantially less frequently than the…
Reviewed for currency November, 2019 Revised February 20, 2021 Acute infectious gastroenteritis is an exceedingly common and widespread illness throughout the world. Noroviruses are major causes of this illness, which is generally self-limited but can result in hospitalization, mortality in…
Rhinoviruses are among the most frequent causes of viral infections in humans. They are the major cause of the common cold and are significant contributors to other upper respiratory syndromes as well as certain lower respiratory illnesses. The term common…