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Category: Clinical Microbiology
Mycoplasma and Ureaplasma, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap59-1.gif /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap59-2.gifAbstract:
Mollicutes are believed to have evolved from clostridium-like gram-positive cells by gene deletion. In humans, mycoplasmas and ureaplasmas are associated with the mucosa, residing predominantly in the respiratory or urogenital tract, rarely penetrating the submucosa, except in cases of immunosuppression or instrumentation, when they may invade the bloodstream and disseminate to various organs and tissues. In humans, mycoplasmas and ureaplasmas may be transmitted by direct contact between hosts, i.e., venereally through genital-genital or oral-genital contact, vertically from mother to offspring either at birth or in utero, by respiratory aerosols or fomites in the case of M. pneumoniae, or even by nosocomial acquisition through transplanted tissues. Polymerase chain reaction (PCR) systems have been developed for all of the clinically important Mycoplasma and Ureaplasma species that infect humans. Typing of human mycoplasmas or ureaplasmas for diagnostic or epidemiological purposes is not recommended at the present time, and the methods are unavailable except in specialized research or reference laboratories. Fluoroquinolones such as levofloxacin and moxifloxacin are usually active against all human mycoplasmal and ureaplasmal species. Eradication of infection under these circumstances can be extremely difficult, requiring prolonged therapy, even when the organisms are susceptible to the expected agents. This difficulty highlights the facts that mollicutes are inhibited but not killed by most commonly used bacteriostatic antimicrobial agents in concentrations achievable in vivo and that a functioning immune system plays an integral part in their eradication.
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Fried-egg-type colonies of Mycoplasma hominis of up to 110 µm in diameter growing on A8 agar. Magnification, ×132.
Fried-egg-type colonies of Mycoplasma hominis of up to 110 µm in diameter growing on A8 agar. Magnification, ×132.
Spherical colonies of Mycoplasma pneumoniae of up to 100 µm in diameter growing on SP4 agar. Magnification, ×126.
Spherical colonies of Mycoplasma pneumoniae of up to 100 µm in diameter growing on SP4 agar. Magnification, ×126.
Granular, brown, urease-positive colonies of Ureaplasma species, 15 to 60 µm in diameter, from a vaginal specimen growing on A8 agar. Magnification, ×100.
Granular, brown, urease-positive colonies of Ureaplasma species, 15 to 60 µm in diameter, from a vaginal specimen growing on A8 agar. Magnification, ×100.
Classification and some distinguishing features of mollicutes
a The total number includes subspecies. The genus Mycoplasma also includes four species not validly published and nine “Candidatus” species of cell wall-less uncultivated parasitic bacteria, eight of which attach to the surface of erythrocytes and may also occur free in the plasma, plus one pneumotrophic “Candidatus” species. Some were previously classified in the genera Haemobartonella and Eperythrozoon. Their G+C contents and sterol requirements are unknown.
b U. urealyticum and U. parvum, formerly considered biovars of U. urealyticum, are now classified as two separate species and are the only ureaplasmas of human origin.
c Phytoplasmas are “Candidatus” species of uncultivable mollicutes of plants and insects genetically related to the Acholeplasmatales.
Classification and some distinguishing features of mollicutes
a The total number includes subspecies. The genus Mycoplasma also includes four species not validly published and nine “Candidatus” species of cell wall-less uncultivated parasitic bacteria, eight of which attach to the surface of erythrocytes and may also occur free in the plasma, plus one pneumotrophic “Candidatus” species. Some were previously classified in the genera Haemobartonella and Eperythrozoon. Their G+C contents and sterol requirements are unknown.
b U. urealyticum and U. parvum, formerly considered biovars of U. urealyticum, are now classified as two separate species and are the only ureaplasmas of human origin.
c Phytoplasmas are “Candidatus” species of uncultivable mollicutes of plants and insects genetically related to the Acholeplasmatales.
Primary sites of colonization, metabolism, and pathogenicity of mollicutes of human origin a
a Symbols: +, positive for trait; –, negative for trait; ?, unknown.
b All isolates reported to date have been from the lower respiratory tract, but no other sites have been sampled.
c The organism has been found in the oropharynx, but it seems unlikely that this is a common or primary location.
d These species metabolize urea.
Primary sites of colonization, metabolism, and pathogenicity of mollicutes of human origin a
a Symbols: +, positive for trait; –, negative for trait; ?, unknown.
b All isolates reported to date have been from the lower respiratory tract, but no other sites have been sampled.
c The organism has been found in the oropharynx, but it seems unlikely that this is a common or primary location.
d These species metabolize urea.
Examples of test kits sold in the United States for detection of serum antibodies to M. pneumoniae a
a This table does not include all commercially available test kits for serological diagnosis of M. pneumoniae infections sold in the United States. It provides descriptions of tests representing various formats and is limited to those products which have been evaluated in independent studies.
Examples of test kits sold in the United States for detection of serum antibodies to M. pneumoniae a
a This table does not include all commercially available test kits for serological diagnosis of M. pneumoniae infections sold in the United States. It provides descriptions of tests representing various formats and is limited to those products which have been evaluated in independent studies.
Ranges of MIC of various antimicrobials for M. pneumoniae, M. hominis, M. fermentans, M. genitalium, and Ureaplasma spp.a
a Data were compiled from multiple published studies in which different methodologies, and often different antimicrobial concentrations, were used. Elevated MICs (≥8 µg/ml) for the occasionally encountered fluoroquinolone-resistant M. hominis and Ureaplasma spp. have not been included in the MIC ranges. ND, no data available.
b Macrolide-susceptible strains only. MICs for M. pneumoniae isolates containing mutations in domain V of rRNA usually exceed 32 µg/ml.
c Tetracycline-susceptible strains only. MICs for isolates containing tet(M) are generally 2–>64 µg/ml.
d Macrolide-susceptible strains only. MICs for Ureaplasma spp. containing mutations in rRNA usually exceed 32 µg/ml.
Ranges of MIC of various antimicrobials for M. pneumoniae, M. hominis, M. fermentans, M. genitalium, and Ureaplasma spp.a
a Data were compiled from multiple published studies in which different methodologies, and often different antimicrobial concentrations, were used. Elevated MICs (≥8 µg/ml) for the occasionally encountered fluoroquinolone-resistant M. hominis and Ureaplasma spp. have not been included in the MIC ranges. ND, no data available.
b Macrolide-susceptible strains only. MICs for M. pneumoniae isolates containing mutations in domain V of rRNA usually exceed 32 µg/ml.
c Tetracycline-susceptible strains only. MICs for isolates containing tet(M) are generally 2–>64 µg/ml.
d Macrolide-susceptible strains only. MICs for Ureaplasma spp. containing mutations in rRNA usually exceed 32 µg/ml.