Microbial penetrability

The sterility of a sterile dosage form can only be guaranteed while it is protected from the surrounding non-sterile environment within a container made from materials impermeable to microbial penetration. 

The sterile condition, can only exist within barriers that protect it from the non-sterile general environment. An essential prerequisite to the maintenance of sterility is for the product or pait of the product that is required to be sterile to be isolated by cnntahunent within a material impermeable to microbial penetration. If the design of the containment system or primary package does not allow the material of containment to be continuous, all-enveloping, and complete, then the sealing surfaces of the m erial of containment, either to itself or to another material of contaioraeot or to the product itself, must also be impermeable to microbial penetration. The barrier properties of the containment system to... 

Dye immersion is not, however, theoretically sound with respect to detecting microbial penetration. 

Table 2 Effect of Glove Condition and Activity on Microbial Penetration Through Gloves...

Resistance to microbial penetration—wet Resistance to microbial penetration—wet Cleanliness—microbial... 

Bursting strength—dry Bursting strength—dry Resistance to microbial penetration—dry... 

Conventional textile dr s and govras will not meet the performance requirements relating to microbial penetration of the latest standards (e.g. EN13795). 

The production of phytoalexins in response to microbes requires a mechanism which enables the plant to recognize the invading organism and subsequently leads to the stimulation of phytoalexin synthesis at the site of microbial penetration. Substances of microbial origin which mediate phytoalexin accumulation in plants have been called elicitors(Ref. 2) and it has been shown in several cases that the culture medium of pathogens contained components which elicited phytoalexin accumulation in the pathogen s host (Ref. 3). Studies on the nature of elicitors have resulted in the partial purification and characterization of a number of molecules from different microbial sources. Elicitors have been reported to have a dependence for activity on a polypeptide or protein (Ref. 4), a glycoprotein (Ref. 5), or polysaccharide (Ref. 6) component. 

Hydrocarbons comprise a majority of the cuticular lipids while wax esters, sterol esters, alcohols and non-esterified fatty acids are also common components. In addition to preventing desiccation, insect waxes also function to prevent abrasion, to act as a barrier against microbial penetration to reduce the absorption of toxic environmental chemicals (including insecticides) and in some cases some components may act in chemical communication (Jackson and Blomquist, 1976). 

Cotton textiles or conventional mixed cotton-polyester textiles, the traditional materials for surgical gowns and drapes, meet a number of requirements, such as comfort, drapeability, good tensile strength, steam permeability and steam sterilisability. However, they will not meet the requirements of the new standard, which includes resistance to microbial penetration, resistance to liquid penetration... 

Resistance to microbial penetration - dry Resistance to microbial penetration - wet Cleanliness - microbial Cleanliness - particulate matter Linting... 

Resistance to microbial penetration is important for all products and in a hospital one can find micro-organisms in the air and in liquids (for example in the blood of the patient). The solid particle, like cotton fibers, has a size of 10-40 pm. Bacteria has a size of 0.5-20 pm. The size of the viruses amounts to 0.01-0.3 pm. 

Barrier effectiveness means that, given the specific circumstances of the procedure, the gown will minimize microbial penetration. Nonwoven drapes and gowns have four levels of barrier performance. Examples of the types of materials that are used in gowns are ... 

Fig. 6.1 Test device to evaluate resistance to microbial penetration in dry conditions.

G. E. Jenneman, M. J. Mclnemey, and R. M. Knapp, Microbial penetration through nutrient saturated Berea sandstone, Environ. Microbial. 50 383-391 (1985). 

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