Microbiology and clinical characteristics of viridans group streptococci in patients with cancer.

This study assessed the microbiology, clinical syndromes, and outcomes of oncologic patients with viridans group streptococci isolated from blood cultures between January 1st, 2013 and December 31st, 2016 in a referral hospital in Mexico using the Bruker MALDI Biotyper. Antimicrobial sensitivity was determined using BD Phoenix 100 according to CLSI M100 standards. Clinical information was obtained from medical records and descriptive analysis was performed. Forty-three patients were included, 22 females and 21 males, aged 42 ± 17 years. Twenty (46.5%) patients had hematological cancer and 23 (53.5%) a solid malignancy. The viridans group streptococci isolated were Streptococcus mitis, 20 (46.5%); Streptococcus anginosus, 14 (32.6%); Streptococcus sanguinis, 7 (16.3%); and Streptococcus salivarius, 2 (4.7%). The main risk factors were pyrimidine antagonist chemotherapy in 22 (51.2%) and neutropenia in 19 (44.2%) cases, respectively. Central line associated bloodstream infection was diagnosed in 18 (41.9%) cases. Septic shock occurred in 20.9% of patients, with an overall mortality of 18.6%. Only four S. mitis revealed penicillin-resistance. Our results are similar to those of other series, identifying these bacteria as emerging pathogens with significant morbidity and mortality in oncologic patients. The MALDI-TOF system increased the rate of viridans group streptococci isolation in this population.