Bacteremia due to Elizabethkingia and related species

Abstract

Elizabethkingia spp. is a gram-negative, non-fermenting rod bacterium that is frequently implicated in hospital outbreaks. Elizabethkingia has a high rate of resistance to antibiotics and a shortage of effective parenteral antibiotics usually occurs in intensive care units. Infection includes neonatal sepsis and meningitis. Recently, a new species of Elizabethkingia, which is closely related to E. meningoseptica ATCC 13253 and E. miricola GTC862, was reported as a human pathogen in Central Africa and named E. anophelis. Our investigation involved 27 Elizabethkingia clinical isolates, which were fully identified through phenotypic and genotypic typing. The isolates were identified as E. meningoseptica by VITEK 2 (bioMereux) and Phoneix (Beckton Dickinson) automated bacterial identification systems. We then re-identified the isolates by 16S rRNA gene sequencing; 23 of the 27 strains were identified as E. anophelis and one was identified as E. miricola instead of E. meningoseptica. Subsequently, we evaluated the performance of the Bruker MALDI-TOF MS system for identification of the E. anophelis strains; many were misidentified as E. meningoseptica or were unidentified. All of the strains were correctly re-identified as E. anophelis when the original Bruker database was expanded with the inclusion of 10 E. anophelis clinical isolates and a standard 〖R26 〗^T strain. We also analysed 23 E. anophelis clinical isolates by biochemical tests, antimicrobial susceptibilities tests and pulsed-field gel electrophoresis. From the biochemical investigation of all isolates and type strain, showing that the conventional biochemical tests are not reliable to differentiate E. anophelis from other Elizabethkingia spp. More than 75% of the isolates tested were susceptible to cotrimoxazole, ciprofloxacin, and cefoperazone-sulbactam, however they were all resistant to aminoglycosides and beta-lactam drugs except one strain. At the PFGE investigation all the strains were not clonally related as shown by PFGE and displayed distinct PFGE fingerprints.