Impact of the MALDI-TOF as a tool for bacterial identification in the frequency of isolation of Aerococcus spp and Actinotignum schaalii in urinary tract infection

Abstract Background Actinotignum schaalii and the genus Aerococcus are considered emerging pathogens, since their isolation has been rising the last years thanks to the improvement of diagnosis techniques, such as the implementation of MALDI-TOF in microbiology laboratories for routine. Their patogenicity is nowadays well described in urinary tract infections affecting susceptible individuals, although both have been isolated from other biological samples. The aim of our study is to evaluate the impact of using mass spectrometry technology on the frequency of isolation of Aerococcus spp and A. schaalii in our hospital. Methods From January 2014 and December 2015 44.654 urines were collected in our laboratory from patients that were expected to have an UTI. Samples were processed using a flow cytometer and cultured if applicable. After 48 h, microbial growth was assessed. Due to the suspicion of an Aerococcus spp or A. schaalii infection identification test was performed using Vitek2 until 2014 and MALDI-TOF from 2015. Results Between the period of study, a total of 35 Aerococcus spp/ A. schaalii isolates were collected from 34 patients. Six isolates were identified by Vitek2 and the other 29 were identified by MALDI-TOF. Out of 34 patients, 33 had at least one risk factor including age >65 years, immunosuppression or cancer, abnormality of the genitourinary tract, recurrent UTI, diabetes or a catheterization. Conclusions Since the implementation of the MALDI-TOF in the laboratory the isolation of Aerococcus spp/ A. schaalii has increased almost five times. The most frequent patient corresponds to an elderly patient with recurrent UTI and cancer.