how to handle difficult personalities

here's the situation.

for the most part, we've always gotten along as a team and take pride in our work. recently, the workload has been getting more demanding and my team, particularly the nurse aides, seems to be falling apart. i try my best to be supportive and positive. i try my best to be fair, objective, and accommodating.

some of these grown women have really inflexible counterproductive attitudes. for instance, a 60 year old staff member continues to hold grudges and bicker with a 20 year old staff member. or the staff member that is constantly paranoid about her other coworkers because she believes that they are singling her out and putting her down. or the one who instigates drama between other staff members. i am in my 30's and honestly, i cannot believe that grown women can act this way. we used to be cohesive team, and now its pointless bickering that eventually affects our work for our patients.

i encourage teamwork and speak to them individually about not taking things personally, and not reacting to the other person. otherwise, i can pick out where the problems lie, but i just don;t have the power to change people's stubborn or negative ways.

what do i do??? im feeling the heat from upper management.