Isolation ofLegionella pneumophilafrom water supplies: comparison of methods based on the guinea-pig and culture media

Abstract

SUMMARY: The detection ofLegionella pneumophilain water via guinea-pig intraperitoneal injection has been compared with direct isolation of these organisms on semiselective BCYEα media. Both techniques were of similar sensitivity, detecting as few as 10²L. pneumophilain 10 ml of water. However, at this concentration, detection using guinea-pig intraperitoneal injection was via the indirect parameters of antibody production and immunofluorescent microscopy. Isolation ofL. pneumophilafrom guinea-pig tissue for further investigation required > 10⁷organisms injected and in this respect is relatively much less sensitive than direct isolation on semiselective BCYEα media. SinceL. micdadeiandL. longbeachaeare inhibited by one of the selective supplements used, other supplements and techniques need to be developed in order to avoid possible inhibition of otherLegionellaspecies.