Use of the MALDI Biotyper system and the microbiological diagnosis algorithm for identification of non-fermenting bacteria isolated from respiratory tract in cystic fibrosis patients

Abstract

The objective of this study was to compare the MALDI Biotyper system and the microbiological diagnosis algorithm for identification of non-fermenting bacteria isolated from respiratory tract in cystic fibrosis patients. The identification and typing algorithm, including bacteriologic, biochemical, and molecular methods as well as the MALDI Biotyper system was used. Using this algorithm, a total of 47 species of non-fermenting microorganisms was identified. The identification of microorganisms belonging to Achromobacter genus and Burkholderia cepacia complex (Bcc) proved to be the most difficult and require a combination of the methods listed above. Achromobacter species were isolated from 89 adults and children with cystic fibrosis, of which 82.7% and 10.6% belonged to Achromobacter ruhlandii and Achromobacter xylosoxidans, respectively. A total of 60 strains (3 species) of Bcc were isolated (32 strains – from adults and 28 strains – from children), of which 83.3% belonged to B. cenocepacia. The Bcc species were isolated from adult and pediatric patients with cystic fibrosis in Moscow (B. cenocepacia), Saint-Petersburg (B. contaminans, B. cepacia) and Khabarovsk (B. cepacia, B. cenocepacia, and B. contaminans). A total of 57 strains (11 species) of Pseudomonas spp. were isolated from adults and children, of which 41 strains (71.9%) were identified as P. aeruginosa (including 8 strains with atypical phenotype). P. aeruginosa proved to be an easier non-fermenting microorganism to be identified (except for isolates with atypical phenotype, where the use of MALDI-TOF mass spectrometry is critical).