Mycoplasma

Mycoplasma is a genus of bacteria that lack a cell wall, making them naturally resistant to antibiotics like beta-lactam that target cell wall synthesis. They can be parasitic or saprotrophic and are among the smallest free-living organisms. Several species are pathogenic to humans, including M. pneumoniae, which causes "walking" pneumonia, and M. genitalium, involved in pelvic inflammatory diseases.

Genus of bacteria: Mycoplasma

Characteristics

Mycoplasma species are pleomorphic, meaning they can change shape due to the lack of a rigid cell wall. They possess a plasma membrane as the outer boundary and are among the smallest organisms, about 0.2 - 0.3 μm in diameter. They exhibit heterotrophic nutrition, with most being parasites due to their inability to synthesise required growth factors.

Pathophysiology

Mycoplasma species have been isolated from women with bacterial vaginosis and pelvic inflammatory disease, with some developing antibiotic resistance. They are associated with infant respiratory distress syndrome, bronchopulmonary dysplasia, and intraventricular haemorrhage in preterm infants.

Diagnosis

Mycoplasma infections are diagnosed through various techniques, including DNA probes, enzyme immunoassays, PCR, plating on sensitive agar, and DNA staining with DAPI or Hoechst. Laboratory contamination of cell cultures by Mycoplasma is a significant issue, often detected through these methods.

Reproduction

Mycoplasma species reproduce by a uni- or multi-polar budding mechanism rather than binary fission. This method has been observed through phase-contrast microscopy and electron microscopy.

Pathogenicity

Mycoplasma pneumoniae is a significant cause of atypical pneumonia, while M. genitalium is linked to pelvic inflammatory diseases. Mycoplasma infections in humans can cause skin eruptions in 17% of cases.

Sexually Transmitted Infections

Mycoplasma and Ureaplasma species are not part of the normal vaginal flora and can be sexually transmitted, negatively affecting fertility. Species like U. urealyticum, M. hominis, M. genitalium, and M. penetrans colonise the human genital tract.

Links to Cancer

Certain Mycoplasma species are frequently detected in different types of cancer cells, showing a strong correlation to malignant transformation in mammalian cells in vitro. They cause gradual changes in cell morphology and genetic material, potentially leading to cancer.

Types of Cancer Associated with Mycoplasma

• Colon Cancer: Positive correlation between M. hyorhinis presence and CD133-positive cells.
• Gastric Cancer: M. hyorhinis infection contributes to stomach cancer development.
• Lung Cancer: Strong correlation between Mycoplasma presence and tumorigenesis.
• Prostate Cancer: The p37 protein from M. hyorhinis promotes prostate cancer cell invasiveness.
• Renal Cancer: Higher Mycoplasma presence in renal cell carcinoma patients compared to healthy controls.

Synthetic Mycoplasma Genome

A fully synthetic genome of a mycoplasmal cell, known as Mycoplasma laboratorium, has been created, capable of self-replication.

Laboratory Contaminant

Mycoplasma contamination in cell cultures is common, with an estimated 11 to 15% of U.S. laboratory cell cultures being contaminated. Detection techniques include DNA probes, enzyme immunoassays, PCR, and staining with DNA stains. Several antibiotic formulations have been developed to address this issue.

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Self-assessment MCQs (single best answer)

What characteristic makes Mycoplasma naturally resistant to certain antibiotics?

Which Mycoplasma species is known to cause "walking" pneumonia?

How do Mycoplasma species primarily obtain nutrients?

Which diagnostic method is NOT commonly used to detect Mycoplasma infections?

What type of reproduction is observed in Mycoplasma species?

Which Mycoplasma species is linked to pelvic inflammatory diseases?

Which cancer type has been associated with Mycoplasma hyorhinis infection?

What is a notable characteristic of Mycoplasma colonies on Hayflick agar?

What is the significance of the synthetic Mycoplasma genome, Mycoplasma laboratorium?

What percentage of U.S. laboratory cell cultures are estimated to be contaminated with Mycoplasma?