The California Public Employment Relations Board will seek a temporary injunction to limit the number of employees from two health care unions who are planning to strike at UC medical centers on May 21.

American Federation of State, County and Municipal Employees 3299, which represents more than 12,500 UC patient care employees, is planning to strike next week in the midst of ongoing contract negotiations with the university that began in June of 2012. University Professional and Technical Employees 9119, a union representing technical workers, is also asking its members to strike in sympathy with AFSCME 3299.

According to the UC statement released Friday, PERB’s notification comes after UC representatives successfully argued that walkouts by certain essential employees pose an imminent threat to public health and safety.

“Shame on them for jeopardizing health services that people need and deserve,” said John Stobo, senior vice president for Health Sciences and Services at the university, in a statement. “It is completely inappropriate to threaten services to patients as a negotiating tactic — the health of our patients must not be held hostage.”

According to the statement, PERB officials told the university they intend to seek the injunction in Sacramento Superior Court on May 20. The injunction request will focus on those UC employees who, in PERB’s view, work in critical health and safety positions.

In response to the PERB statement about the injunction, AFSCME President Kathryn Lybarger also issued a statement on Friday discussing the union’s plan to ensure patient safety during the striking process.

“We are pleased that the PERB has affirmed the right of UC Patient Care Technical Workers to strike and has produced a determination that is both consistent with the spirit of AFSCME 3299’s Patient Protection Measures,” Lybarger said in the statement. “That said, we are disappointed that the PERB’s proposed limited injunction unnecessarily covers nearly two dozen patient care workers that would have been available to meet emergent needs through our Patient Protection Task Force.”