Current testing methods: brief technology background

Current microbiological testing is discussed in detail in Chapters 11 and 12. Preventive measures, inactivation and microbiology testing as performed, at least in developed countries, guarantee an extremely safe blood supply (Barbara, 1998). Recently, a technologically demanding and conceptually different type of testing, NAT (discussed in Chapter 14), has been implemented as a routine procedure. In countries with high development indices, residual risk estimates, especially for transfusion-transmitted viruses, are very low (Soldan et al., 2003) and not many other medical procedures (if any) can match them. Of course, there is always room for improvement on safety: a level of automation to limit operator-related errors, cost-efficiency, etc.

In order to compare the power of current testing techniques with the potential of newly developed candidate next generation testing techniques, a brief summary of current testing technologies follows.

Unique features of microbiological blood screening

Various aspects of microbiological blood screening make it a rather unique process when compared with other testing procedures for infectious agents (see Table 18.1). Under usual circumstances people are tested for infectious agents on the basis of symptoms at or after a visit to a primary care physician, or during a stay in hospital. In other words, the physician or hospital microbiology laboratory personnel know what range of tests to perform on the basis of the referral or a preliminary diagnosis. Consequently, a large proportion of tested samples will give a positive result for one or more tested pathogens.