A while back, I was asked the following question: [How comparable is a] BS/MS in med tech vs a BS/MS in straight chemistry or microbiology?
Two of the four major disciplines within Medical Technology are Clinical Chemistry and Microbiology, so there is definitely some overlap. However, I'd say that there is probably a fair bit of difference between a Chemistry major and the discipline of Clinical Chemistry. The same holds true for Microbiology. The issue becomes, what is the focus of the university programs curriculum?
If the Microbiology B.S. degree has more of an environmental focus, the student is going to have a lot less exposure to medically relevant organisms, and probably will not know the tests needed to properly differentiate phenotypically similar organisms, which is a core skill in Medical Technology. Same goes for the Chemistry major. If they have a solid background in Biochemistry, they'll be on their way, but will they have enough knowledge in some basic laboratory skills to run some of the non-standard tests (especially when it comes to drug testing and validation tests, which are usually not machine-based)? Plus they'll be missing the instrumentation classes necessary for the job (which often includes troubleshooting and routine maintenance).
That is why, while both majors can be used to work an individual into ASCP certification (which is a standard registry accepted by all hospitals in the USA), on their own they are not sufficient. In most cases, the individual with a BS in Microbiology and/or Chemistry is looking at about a year of additional training before they can sit for the ASCP Board of Registry Chemistry or Microbiology Certification exam. They can, however, be employed during that time, but it will be a position which will be heavily supervised.