well, I can give you quite a lot of information, unfortunately.
1. 16mm PPD test shows that, during your life, you were exposed to TB. that is quite certain. many people do not get actually sick of TB, but they are exposed to the bacteria and become carriers. for as long as the disease is latent, you can't transmit the bacteria to somebody else. But in 5-10% latent carriers can the disease can become active. therefore the need to take preventive medication, which reduces the chances to get it active to 1-2%.
2. you can try to ask for a waiver and, if you are a VIP in your company, maybe you can get one. If you are just a simple employee, chances are you will be kicked out.
3. There might be significant side effectes, or insignificant. For the majority of people, the side effects of antibiotics are minimal (urine gets orange). some people might experience other simptoms (headacke, nausea, etc). It varies from person to person. If your eye whites get a a bit yellow you should report to the doctor immediately (liver damage. if you stop the medication, it's ok, not permanent).
4. there are 2 options of treatment:
*once per week, 12 tablets, taken in the hospital, for 3 months.
*daily tablets (3pcs), which you can take at home, for 4 months.
you need to report to doctor after 2 months, for a check.
If you think your health is not perfect, you might want to go for the daily dose (smaller amounts of antibiotics, taken at home).

In the end, the choice is yours: either you take the medication (with probably manageble side effects), and you keep your job, or you refuse, and most probably you will be kicked out.

Good luck.