IMPROVEMENT OF GROWTH OF CHLAMYDIA-PNEUMONIAE ON HEP-2 CELLS BY PRETREATMENT WITH POLYETHYLENE-GLYCOL IN COMBINATION WITH ADDITIONAL CENTRIFUGATION AND EXTENSION OF CULTURE TIME

The following adaptations led to improved growth of Chlamydia pneumoni ae on HEp-2 cells compared to that by the standard method: monolayer p reincubation with 7% polyethylene glycol (PEG), extension of incubatio n time to 7 days, and extension of incubation to 7 days in combination with centrifugation on days 3, 4, and 5, These adaptations resulted i n approximate increases in numbers of inclusion-forming units (IFU) of 2-, 5-, and 69-fold, respectively, A combination of preincubation wit h PEG, prolonged incubation, and centrifugation on days 3, 4, and 5 in creased the numbers of IFU >300-fold, This is therefore recommended as the optimal method for culturing C. pneumoniae.