[Prevalence of Mycoplasma orale as a contaminant of cell cultures in Argentina].

Over a period of 4 years 200 cell cultures were analysed for the presence of mycoplasma. Cultures were established cell lines from different origins, namely monkey, mouse and human, hybrid cell cultures and primary cultures. The cultures belonged to various research and industrial laboratories located in different areas of the country. Seventy per cent of investigated cultures were found to be contaminated with mycoplasma using a DNA fluorescent stain. Fifty cultures, selected at random out of the contaminated cultures, were further investigated to identify the prevalent serotype. For that purpose immunofluorescent reactions were performed using immune sera raised against several mycoplasma strains routinely found among contaminated cultures. Forty one cultures were contaminated with a single type of mycoplasma, whereas in the remaining nine, two or even three serotypes were detected. Mycoplasma orale II contaminated 40% of single infected cultures, followed by M. hyorhinis and A. laidlawii-A (12% each), M. arginini (5%), M. orale III (8%), A. laidlawii-B (2%). We were unable to serotype the remaining positive cultures, because of the lack of a full battery of immune sera against all known serotypes. The prevalence of M. orale in mycoplasma contaminated cultures thus far tested, indicates that human handling would be the main source of infection. This situation could be modified by avoiding mouth pipetting and adopting good microbiological techniques.