Do human mycoplasmas rely on iron?

A review article published in the Computational and Structural Biotechnology Journal describes the putative iron-enzymes, transporters, and metalloregulators of four relevant human mycoplasmas and questions the use of iron by these minimal organisms.

Alex Perálvarez-Marín, et al., Computational and Structural Biotechnology Journal, 2021.
Metal utilization in genome-reduced bacteria: do human mycoplasmas rely on iron??


Mycoplasmas are parasitic bacteria with streamlined genomes and complex nutritional requirements. Although iron is vital for almost all organisms, its utilization by mycoplasmas is controversial. Despite its minimalist nature, mycoplasmas can survive and persist within the host, where iron availability is rigorously restricted through nutritional immunity. In this review, we describe the putative iron-enzymes, transporters, and metalloregulators of four relevant human mycoplasmas. This work brings in light critical differences in the mycoplasma-iron interplay. Mycoplasma penetrans, the species with the largest genome (1.36 Mb), shows a more classic repertoire of iron-related proteins, including different enzymes using iron-sulfur clusters as well as iron storage and transport systems. In contrast, the iron requirement is less apparent in the three species with markedly reduced genomes, Mycoplasma genitalium (0.58 Mb), Mycoplasma hominis (0.67 Mb) and Mycoplasma pneumoniae (0.82 Mb), as they exhibit only a few proteins possibly involved in iron homeostasis. The multiple facets of iron metabolism in mycoplasmas illustrate the remarkable evolutive potential of these minimal organisms when facing nutritional immunity and question the dependence of several human-infecting species for iron. Collectively, our data contribute to better understand the unique biology and infective strategies of these successful pathogens.

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One Health in Mycoplasmas: Antimicrobial Susceptibility and Resistance in Mycoplasmas Infecting Humans, Animals, Plants and Insects”

A special issue of Antibiotics

an open access journal published monthly online by MDPI.

Mycoplasmas are among the smallest forms of life in nature and exist as commensals or pathogens of organisms across the tree of life. They are associated with disease in premature newborn babies and sexually transmitted disease in adults, infectious respiratory disease in domesticated farm animals (pigs, chickens and cattle), as well as wild game (antelope, camels and flamingos), causing infectious damage to fruit crops of citrus trees, and have even been found in jellyfish. The entire over-arching class of Mollicutes to which they belong have no cell wall, scavenge nucleotides from their host and commonly reside within host cells, making them completely resistant to most classes of antibiotics. Therefore, monitoring the evolution and spread of resistance to the remaining effective antibiotics is of international concern. This Special Issue is dedicated to the International Organisation of Mycoplasmology in its continued effort to monitor resistance, develop new antibiotic therapies and guidelines, and develop alternatives for treating Mycoplasma infection in the face of diminishing effective antibiotics.

Dr. Owen B. Spiller
Guest Editor

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Mycoplasma agalactiae: The Sole Cause of Classical Contagious Agalactia?

A recent commentary by Migliore at al. (2021) recommends that contagious agalactia (CA) should only be diagnosed and confirmed when M. agalactiae is detected either by isolation or molecular methods. The other three mycoplasmas classically associated with CA (M. mycoides subsp. capri, M. capricolum subsp. capricolum and M. putrefaciens) should removed from the OIE Manual of Diagnostic Tests and Vaccines in Terrestrial Animals and associated sources.


For over thirty years, contagious agalactia has been recognized as a mycoplasma disease affecting small ruminants caused by four different pathogens: Mycoplasma agalactiae, Mycoplasma mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum and Mycoplasma putrefaciens which were previously thought to produce clinically similar diseases. Today, with major advances in diagnosis enabling the rapid identification by molecular methods of causative mycoplasmas from infected flocks, it is time to revisit this issue. In this paper, we discuss and argue the reasons to support Mycoplasma agalactiae infection as the sole cause of contagious agalactia.

Migliore S, Puleio R, Nicholas RAJ, Loria GR. Mycoplasma agalactiae: The Sole Cause of Classical Contagious Agalactia? Animals. 2021; 11(6):1782.