Quality control of small-volume sterile products

A method for bacterial surveillance of small-volume sterile products in hospitals was developed and tested. The criteria for the method of quality control were to: (1) assure detection of contamination associated with touch, which could occur during the filling process; (2) be economically feasible; (3) be simple and easy to implement; and (4) be versatile in adapting to small-volume sterile packages with and without needles. Ten percent of each lot of prepackaged unit dose syringes is tested by filtration through a sterile micropore filter. The filter unit is incubated after fluid thioglycollate medium has been added. If turbidity or color change is found, further testing with blood agar and gram staining is performed to identify the organism. The effectiveness of the method was tested by adding E. coli to one lot within each of several lots tested of six products. The inoculated samples were stored under refrigeration for three days before testing. With one exception, the E. coli was detected in the samples. Growth did not occur in any of the noninoculated units. The apparent false negative result was believed to be caused by the bacteriostatic agent killing the organism during the three-day storage period.