Difco Laboratories Incorporated

Nadine M Sullivan

Jerry W Smith

Gideon Eden

Ruth F Eden

A culture package system comprising a package preferably in the form of a container containing one or more conventional culture media dishes containing solidified culture media. Each dish includes a bottom wall and a peripheral side wall and a removable cover having a bottom wall and a peripheral side side wall which is loosely telescoped over the dish. A plurality of the dishes are preferably provided in inverted stacked relation in the container. A cover is hermetically sealed to close the container. The interior of the package has a gaseous atmosphere having less than 1% oxygen. An oxygen absorber is placed in the package to facilitate maintaining the atmosphere at less than 1% oxygen. Preferably a moisture absorber is also placed in the package. The package is made of plastic material which is impermeable to oxygen and moisture and preferably is in the form of a container which has a base wall and a peripheral wall and a cover sealed thereto.

Culture dish package and method of making

In such a method and apparatus for detecting microbiological growth in a sealed sample container, pressure within the headspace of the container is monitored for detecting rate of change of such headspace pressure. Presence of microbiological growth within the container is indicated as a function of rate of change of headspace pressure. The rate of pressure change is compared with a standard rate for a family of microorganisms., and growth is indicated when the absolute value of the rate of pressure change (which may be positive or negative) exceeds the absolute value of the standard rate (which also may be positive or negative). For detecting microbiological growths which may have differing growth rates, absolute value of rate of pressure change is compared to a plurality of standard rates for differing families of microorganisms. At least some of the rates may be positive, corresponding to growth of gas-producing organisms, and at least some of the rates may be negative, corresponding to growth of gas-consuming organisms. In either case, microbiological growth in the test sample is indicated when absolute mathematical value of the rate of headspace pressure change exceeds absolute mathematical value of any of the standard rates.

Detecting microbiological growth

A culture media package comprising a container having a bottom wall and a peripheral side wall which is substantially filled with a culture medium, a removable insert over the top wall and having a portion defining a planar undersurface and a removable protective cover over the container and insert. The container and insert have radially extending flanges which are bonded to one another. The package is made by filling the container with a molten culture medium in a sterile environment, bonding the insert to the container in a sterile environment, inverting the sealed container such that the molten medium contacts the planar surface of the insert permitting any gases and bubbles to rise toward a space adjacent the bottom of the container and maintaining the container with the insert thereon in an inverted position until the medium has solidified. The removable cover may be applied to the sealed package of the container and insert either before the sealed package is inverted or after the medium has solidified. The package is preferably made from continuous molded plastic strips of connected containers and connected inserts which are filled with medium and sealed, severed from one another, thereafter inverted while the culture medium is still molten and permitted to remain in the inverted position until the culture medium has solidified.

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Ann Arbor, MI, United States of America

Nadine M Sullivan