Massachusetts-based Senior Housing Properties Trust has agreed to acquire 23 Class A medical office buildings, including six in Louisiana, for $539 million.

The locations of the Louisiana buildings were not immediately available. However, Senior Housing Properties said the Louisiana properties have 40,575 square feet of space and their principal tenant is Fresenius Medical Care, a dialysis service provider.

Fresenius has nearly 100 locations in Louisiana. The state filed a lawsuit against Fresenius in July over the use of two dialysis drugs that could contribute to fatal heart attacks. The drugs, GranuFlo and NaturaLyte, have been recalled by the federal government.