High prevalence of division II (cfiA positive) isolates among blood stream Bacteroides fragilis in Slovenia as determined by MALDI-TOF MS. (August 2019)

• Record Type: Journal Article
• Authors: Jeverica, Samo; Sóki, József; Premru, Manica Mueller; Nagy, Elizabeth; Papst, Lea
• Is Part Of: Anaerobe. Volume 58(2019)
• Page Start: 30
• Page End: 34
• Publication Date: 2019-08
• Subjects: Bacteroides fragilis -- Antimicrobial resistance -- cfiA carbapenemase -- Blood stream isolates; Anaerobic infections -- Periodicals; Anaerobic bacteria -- Periodicals; Bacterial diseases -- Periodicals; Computer network resources; Anaerobic protozoa -- Periodicals; 579.3
• DOI: 10.1016/j.anaerobe.2019.01.011
• Languages: English
• ISSNs: 1075-9964

Abstract

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. Highlights: 14.9% proportion of division II ( cfiA positive) B. fragilis among blood culture isolates. Division II ( cfiA positive) B. fragilis are more resistant toβ-lactam antibiotics than division I ( cfiA negative). Empiric therapy for division II isolates should not include carbapenem or co-amoxiclav.