Patient-nurse ratio as an index related to healthcare-associated infections: a surveillance study oleh Daniela de la Rosa-Zamboni, Miroslava I. Carrasco-González, Norma de Blas-Barrientos, María L. Flores-Constatino, Erika Flores-Zamora, Martha Camacho-Pérez, Itzel G. Neri-Saldaña, Ana C. Guerrero-Díaz