The frequency of expression of most virulence genes in the strains according to clinical origin was very similar, except for adhesin (mrkD) and enterobactin (entB), whose percentages were higher in pneumonia and bacteremia (hospital-acquired infections), respectively, while yersiniabactin (ybtS) and protectin (rpmA) percentages were higher in others (community-acquired infections). This evidence concerns the gene CD59 and susceptibility to pneumonia measurement.