High prevalence of division II (cfiA positive) isolates among blood stream Bacteroides fragilis in Slovenia as determined by MALDI-TOF MS

Samo Jeverica, J. Sóki, Manica Mueller Premru, E. Nagy, Lea Papst

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Bacteroides fragilis can be classified into division I (cfiA negative) and division II (cfiA positive) isolates. Division II isolates have a silent chromosomal carbapenemase gene (cfiA) that can become overexpressed by an insertion of a mobile genetic element and thus develop a phenotypic resistance to carbapenems. Aims of our study were (i) to determine the prevalence of B. fragilis division II (cfiA positive) isolates among blood stream and non-blood stream isolates from two major Slovenian tertiary-care hospitals and (ii) to assess its influence on phenotypic resistance to imipenem. Consecutive non-duplicate B. fragilis isolates from blood stream and non-blood stream specimens were included in the analysis from 2015 to 2017 period. Data from laboratory information system were matched with mass spectra obtained with Microflex LT instrument and MALDI Biotyper 3.1 software (Bruker Daltonik, Bremen, Germany). All mass spectra were reanalyzed using Bruker taxonomy library. Spectra with a log(score) > 2.0 were further analyzed with cfiA library that separates B. fragilis division I and II isolates based on a log(score) value difference of >0.3. Minimal inhibitory concentrations (MICs) for imipenem were determined with Etest (bioMérieux, Marcy l’Étoile, France), using supplemented Brucella agar and EUCAST breakpoints (S ≤ 2 mg/L, R > 8 mg/L). Altogether 623 consecutive B. fragilis isolates were included in the analysis; 47 (7.5%) were isolated from blood stream and 576 (92.5%) from non-blood stream specimens. Among all study isolates, 51 (8.2%) proved to belong to division II (cfiA positive). The proportions of division II isolates among blood stream and non-blood stream isolates were 14.9% and 7.6%, respectively (p = 0.081, ns). In total, 1.3% (n = 8) were non-susceptible to imipenem (MIC >2 mg/L); 4.3% (n = 2) among blood stream and 1% (n = 6) among non-blood stream isolates. All imipenem resistant isolates belonged to division II. Modal MICs (MIC range) were 0.064 mg/L (0.016 mg/L-2 mg/L) and 0.125 mg/L (0.064 mg/L-≥32 mg/L) for division I and II isolates, respectively.

Original languageEnglish
Pages (from-to)30-34
Number of pages5
JournalAnaerobe
Volume58
DOIs
Publication statusPublished - Aug 1 2019

Fingerprint

Slovenia
Bacteroides fragilis
Matrix-Assisted Laser Desorption-Ionization Mass Spectrometry
Imipenem
Libraries
Disk Diffusion Antimicrobial Tests
Clinical Laboratory Information Systems
Interspersed Repetitive Sequences
Brucella
Carbapenems
Tertiary Healthcare
Tertiary Care Centers
Agar
France
Germany
Software
Genes

Keywords

  • Antimicrobial resistance
  • Bacteroides fragilis
  • Blood stream isolates
  • cfiA carbapenemase

ASJC Scopus subject areas

  • Microbiology
  • Infectious Diseases

Cite this

High prevalence of division II (cfiA positive) isolates among blood stream Bacteroides fragilis in Slovenia as determined by MALDI-TOF MS. / Jeverica, Samo; Sóki, J.; Premru, Manica Mueller; Nagy, E.; Papst, Lea.

In: Anaerobe, Vol. 58, 01.08.2019, p. 30-34.

Research output: Contribution to journalArticle

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abstract = "Bacteroides fragilis can be classified into division I (cfiA negative) and division II (cfiA positive) isolates. Division II isolates have a silent chromosomal carbapenemase gene (cfiA) that can become overexpressed by an insertion of a mobile genetic element and thus develop a phenotypic resistance to carbapenems. Aims of our study were (i) to determine the prevalence of B. fragilis division II (cfiA positive) isolates among blood stream and non-blood stream isolates from two major Slovenian tertiary-care hospitals and (ii) to assess its influence on phenotypic resistance to imipenem. Consecutive non-duplicate B. fragilis isolates from blood stream and non-blood stream specimens were included in the analysis from 2015 to 2017 period. Data from laboratory information system were matched with mass spectra obtained with Microflex LT instrument and MALDI Biotyper 3.1 software (Bruker Daltonik, Bremen, Germany). All mass spectra were reanalyzed using Bruker taxonomy library. Spectra with a log(score) > 2.0 were further analyzed with cfiA library that separates B. fragilis division I and II isolates based on a log(score) value difference of >0.3. Minimal inhibitory concentrations (MICs) for imipenem were determined with Etest (bioM{\'e}rieux, Marcy l’{\'E}toile, France), using supplemented Brucella agar and EUCAST breakpoints (S ≤ 2 mg/L, R > 8 mg/L). Altogether 623 consecutive B. fragilis isolates were included in the analysis; 47 (7.5{\%}) were isolated from blood stream and 576 (92.5{\%}) from non-blood stream specimens. Among all study isolates, 51 (8.2{\%}) proved to belong to division II (cfiA positive). The proportions of division II isolates among blood stream and non-blood stream isolates were 14.9{\%} and 7.6{\%}, respectively (p = 0.081, ns). In total, 1.3{\%} (n = 8) were non-susceptible to imipenem (MIC >2 mg/L); 4.3{\%} (n = 2) among blood stream and 1{\%} (n = 6) among non-blood stream isolates. All imipenem resistant isolates belonged to division II. Modal MICs (MIC range) were 0.064 mg/L (0.016 mg/L-2 mg/L) and 0.125 mg/L (0.064 mg/L-≥32 mg/L) for division I and II isolates, respectively.",
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