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Observations on the possible origin of Mycoplasma fermentans incognitus strain based on antibiotic sensitivity tests
1Mycoplasma Experience Ltd, Reigate, Surrey, UK.
Abstract:
Mycoplasma fermentans (incognitus strain), isolated during transfection studies in NIH/3T3 cells with DNA extracted from Kaposi's sarcoma tissue from a patient suffering from AIDS, showed high levels of resistance to numerous aminoglycoside antibiotics (MICs > 250 to > 500 mg/L) and in this respect matched the aminoglycoside resistance patterns of M. fermentans strains isolated recently from tissue culture cells. Two M. fermentans strains isolated from urine deposits from AIDS patients, without the use of cell cultures, and six M. fermentans isolates from patients with acute respiratory infections differed markedly from the incognitus strain, in that they were sensitive to aminoglycosides (MIC range 0.25-25 mg/L). A much older strain (K7) isolated from leukaemic bone marrow tissue in the 1960s, with the aid of cell cultures, was resistant to streptomycin (MIC > 250 mg/L) but sensitive to other aminoglycosides (MIC range 0.625-6.25 mg/L). These results suggest that, although the aminoglycoside-resistance in M. fermentans incognitus could have developed during the isolation process or through treatment of the AIDS patient with aminoglycosides, in view of the unusual manner in which the strain was isolated, its multiple aminoglycoside resistance and the fact that other M. fermentans strains isolated from AIDS patients, without the use of tissue culture cells, were aminoglycoside-sensitive, it is more likely that it was a tissue culture contaminant.
Insights
The Mycoplasma fermentans incognitus strain exhibits high aminoglycoside antibiotic resistance, unlike other strains isolated from patients. This suggests it was likely a tissue culture contaminant rather than a true clinical isolate.
Area of Science:
- Microbiology
- Antibiotic Resistance
- Cell Culture Contamination
Background:
- Mycoplasma fermentans is a bacterium that can infect humans.
- The incognitus strain was isolated from a patient with AIDS during transfection studies.
- Aminoglycoside antibiotics are commonly used to treat bacterial infections.
Purpose of the Study:
- To investigate the aminoglycoside antibiotic resistance patterns of the Mycoplasma fermentans incognitus strain.
- To compare the resistance of the incognitus strain with other Mycoplasma fermentans isolates.
- To determine the origin and significance of the incognitus strain's resistance.
Main Methods:
- Isolation of Mycoplasma fermentans strains from various sources, including cell cultures, urine deposits, and bone marrow tissue.
- Determination of minimum inhibitory concentrations (MICs) for various aminoglycoside antibiotics against the isolated strains.
- Comparison of antibiotic resistance profiles between different strains and isolation methods.
Main Results:
- The Mycoplasma fermentans incognitus strain displayed high resistance to numerous aminoglycoside antibiotics (MICs > 250 to > 500 mg/L).
- Other Mycoplasma fermentans strains, including those from AIDS patients' urine and respiratory infections, were sensitive to aminoglycosides (MIC range 0.25-25 mg/L).
- An older strain (K7) showed intermediate resistance, being resistant to streptomycin but sensitive to other aminoglycosides.
Conclusions:
- The Mycoplasma fermentans incognitus strain's high aminoglycoside resistance is unusual compared to other clinical isolates.
- The resistance may have developed during isolation or due to patient treatment, but is more likely indicative of a tissue culture contaminant.
- The isolation method and resistance profile strongly suggest the incognitus strain was not a genuine clinical isolate from the AIDS patient.
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