Ph.D

Hi Madhurjya,
Some universities enroll students into an MSP/Ph.D program. So in this case, you don't have to enroll in MS and Ph.D programs separately. Gaining admissions into MS will lead to Ph.D, of course, you must complete all course and research requirements and by no means, you can do Ph.D without completing the MS component or an MS program in itself.

IITs, IISc and NITs are the top most reputed institutes in India.
If you want to pursue PhD in chemistry then you have a great opportunity to get admission in that colleges which is IIT JAM Exam.
It is an entrance exam for M.Sc. which is conducted by IITs and IISc. By qualifying JAM exam you can get admission in IITs for M.Sc. (2 years), Joint M.Sc.-PhD, M.Sc.-PhD Dual Degree, M.Sc.-M.Tech., M.Sc.-M.S. (Research)/PhD Dual Degree and other Post-Bachelor Degree Programs.

Please refer to the link provided below for a list of top private colleges which offer courses in PhD, medical microbiology.
https://www.shiksha.com/science/colleges/microbiology-colleges-india?uaf[]=base_course&ts=20414235&rf=filters&bc[]=124&ss[]=sp_336

Doctor of Philosophy (Ph.D.) in Nursing and Doctor of Nursing Practice (DNP) degree programs are for registered nurses who want to advance in the field. Career options will vary based on the type of degree program completed, but typical career paths are as follows:
Nursing or medical profession researcher
Post secondary nursing instructor
Nurse practitioner
Clinical nurse specialist
Nurse midwife

Hi Aditi,
For Ph.D admissions, you need to first see which university offers Ph.D and research program in your discipline. Then you need to communicate with the department's supervisor. It is different than a typical MS or BS program. So, firstly, you need to research about which universities have related research work and look out for the Ph.D notifications, proceed accordingly. As an international applicant, you must take the IELTS/TOEFL or the GRE, etc., depending on where you are planning to pursue your Ph.D.