Registered nurses at 15 hospitals owned by the national chain, Hospital Corporation of America, have voted by an "overwhelming majority" to strike if contract negotiations are not resolved, a nurses union announced this week.

The hospitals include some in Florida and the Tampa Bay area, with the rest in Missouri, Kansas, Texas and Nevada.

The National Nurses Organizing Committee said its negotiators are working with HCA to ensure safe staffing ratios, raise wages and improve security for nurses.

In July, nurses at five local HCA hospitals picketed to raise awareness of the issues they face. Rosanne O'Malley, a registered nurse at the Medical Center of Trinity and chief nurse representative for the union, says safe staffing is the top issue.

"It's very hard to do our jobs when we're expected to take on too many patients," said O'Malley, who has worked as a registered nurse for 31 years and a decade at Trinity. "Our company makes a huge profit every year, and we'd just like to see the people who do the work get some of that money. We would like to see annual raises for all nurses. The cost of living is going up and our wages are not going up at the same ratios."

The union also is urging hospital management to address nurse turnover rates and invest in the recruitment and retention of nurses. O'Malley said the rise in the use of drugs and weapons is a growing concern for nurses treating unstable patients.

"There are unsafe conditions and it's escalating," she said.

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Union officials say that HCA hospitals struggle with retaining staff, with more than 50 percent of nurses leaving their jobs within three years.

An HCA spokeswoman said it's not uncommon for talk of strikes to bubble up during contract negotiations.

"We have bargaining dates scheduled later this month and we look forward to the union's response to the proposal we provided to them back in July," said JC Sadler, a spokeswoman for HCA's West Florida division.

She touted the company's "culture of compassion," adding: "We want to assure our community that neither this — nor any other action — will ever come between us and our commitment to the high-quality care and services we offer our patients and this community on a daily basis."

The strike authorization vote does not mean nurses will necessarily go on strike, union officials said. But it gives them the opportunity to do so if they feel the issues they face are not being addressed.

"Nurses are making it absolutely clear that we are ready to strike to ensure optimal care for our patients," Jack Hood, a registered nurse in the ICU at Oak Hill Hospital in Brooksville, said in a statement.

"From Florida to Nevada, we are united in our commitment to negotiating a contract that provides solutions to the issues we are raising including turnover, recruitment and retention, and consistent compliance with staffing grids."

The hospitals potentially affected by a strike employ nearly 7,000 nurses affiliated with the union. Four thousand of them live in Florida, union officials said.

HCA nurses at Northside Hospital in St. Petersburg, St. Petersburg General Hospital, Oak Hill Hospital in Brooksville and the Trinity Medical Center are being represented in the negotiations. HCA hospitals in Bradenton, Port Charlotte and Sarasota are affected as well.

Registered nurses affiliated with the National Nurses Organizing Committee have been in talks since contracts expired in May in Florida. No strike date has been set at this time. If a strike were to happen, participating nurses would give their hospital 10 days advance notice so management could prepare, union officials said.

The committee is affiliated with National Nurses United, one of the largest and fastest growing unions of registered nurses with 150,000 members.

Local HCA-employed nurses affiliated with National Nurses United have picketed for better wages several times in recent years. In 2015, they raised similar issues, calling for better wages and staffing levels. Local picketing also was reported in 2012.

Contact Justine Griffin at jgriffin@tampabay.com or (727) 893-8467. Follow @SunBizGriffin.