Ingrid Wybo

Third Belgian multicentre survey of antibiotic susceptibility of anaerobic bacteria.

OBJECTIVES To collect recent data on the susceptibility of anaerobes and to compare them with results from previous studies. METHODS Four hundred and forty-three anaerobic clinical isolates from various body sites were prospectively collected from October 2003 to February 2005 in nine Belgian hospitals. MICs were determined for nine anti-anaerobic and three recently developed antibiotics. RESULTS Most gram-negative bacilli except Fusobacterium spp. were resistant to penicillin. Piperacillin/tazobactam, metronidazole, chloramphenicol, meropenem and amoxicillin/clavulanic acid were very active against all groups, but only 86% of Bacteroides fragilis group strains were susceptible to the latter. Cefoxitin, cefotetan and clindamycin were less active. In particular, only 62%, 52% and 48% of B. fragilis group strains were susceptible, respectively. Clindamycin shows a continuing decrease in activity, as 83% were still susceptible in 1987 and 66% in 1993-94. Anti-anaerobic activity of the new antibiotics is interesting, with MIC50 and MIC90 of 1 and >32 mg/L for moxifloxacin, 2 and 4 mg/L for linezolid and 0.5 and 8 mg/L for tigecycline. CONCLUSIONS The susceptibility of anaerobic bacteria remains stable in Belgium, except for clindamycin, which shows a continuous decrease in activity. However, for each of the tested antibiotics, at least a few resistant organisms were detected. Consequently, for severe infections involving anaerobic bacteria, it could be advisable to perform microbiological testing instead of relying on known susceptibility profiles. Periodically monitoring background susceptibility remains necessary to guide empirical therapy.

Isolation of Arcobacter skirrowii from a Patient with Chronic Diarrhea

The genus Arcobacter currently includes four species ([7][1]). Two species, Arcobacter cryaerophilus and Arcobacter butzleri , have been associated with human disease. They were mainly isolated from patients with diarrhea and bacteremia ([2][2], [3][3], [6][4]). Arcobacter nitrofigilis has been

Differentiation of cfiA-Negative and cfiA-Positive Bacteroides fragilis Isolates by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

ABSTRACT Carbapenem resistance in Bacteroides fragilis is associated with cfiA-encoded class B metallo-beta-lactamase. cfiA-negative and cfiA-positive isolates belong to genotypically distinct groups. Of a total of 248 B. fragilis isolates included in this study, 214 were susceptible, 10 were intermediate, and 24 were resistant to meropenem. We show that matrix-assisted laser desorption ionization–time of flight mass spectrometry is able to differentiate between cfiA-negative and cfiA-positive isolates and predict carbapenem resistance in a routine laboratory setting.

Outbreak of Infection by Carbapenem-Resistant Acinetobacter baumannii Producing the Carbapenemase OXA-58 in Belgium

ABSTRACT Carbapenem-resistant Acinetobacter baumannii isolates were obtained from 17 patients between September 2004 and August 2005 at the Academisch Ziekenhuis Vrije Universiteit Brussel, Brussels, Belgium. These multidrug-resistant isolates, which belonged to a single clone, remained susceptible to colistin and tigecycline only and produced the carbapenem-hydrolyzing oxacillinase OXA-58. This study highlights the importance of the intercountry spread of this β-lactamase-mediated resistance mechanism and its epidemic evolution.

Species Identification of Clinical Prevotella Isolates by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

ABSTRACT The performance of matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) for species identification of Prevotella was evaluated and compared with 16S rRNA gene sequencing. Using a Bruker database, 62.7% of the 102 clinical isolates were identified to the species level and 73.5% to the genus level. Extension of the commercial database improved these figures to, respectively, 83.3% and 89.2%. MALDI-TOF MS identification of Prevotella is reliable but needs a more extensive database.

Vitek 2 ANC card versus BBL Crystal Anaerobe and RapID ANA II for identification of clinical anaerobic bacteria.

The Vitek 2 Anaerobe and Corynebacterium Identification Card (ANC) was recently evaluated in a multicentre study. In the present work, this system was compared with the BBL Crystal Anaerobe and RapID ANA II panels. These kits were tested using 196 strains of anaerobes that had been previously identified by gas-liquid chromatography. Identification to the species or to the genus level was 75.0%, 81.1% and 70.9% for Crystal, RapID and Vitek, respectively. Vitek ANC failed to provide any identification in 20.4% of the strains, but it had fewer misidentifications than RapID. The confidence factors provided on the results report of each kit were not always correlated with a lower risk of major errors, with the exception of Vitek 2 in which a confidence factor higher than 0.86 excluded the risk of misidentification in more than 87% of isolates. The lower rate of identification by the Vitek and Crystal panels is mostly due the lower ability of these systems to identify the Clostridia. Overall, the three panels are comparable but need improvement to a better accuracy.

Correct Implementation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry in Routine Clinical Microbiology

As we have been users of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) since January 2009, we read with much interest the paper of van Veen et al. ([9][1]) in a recent issue of the Journal of Clinical Microbiology. We would like to respond to two issues

Staphylococcus jettensis sp. nov., a coagulase-negative staphylococcal species isolated from human clinical specimens.

Eight coagulase-negative, novobiocin-susceptible staphylococcal strains were isolated from human clinical specimens at two different Belgian medical facilities. All strains were non-motile, Gram-stain-positive, catalase-positive cocci. DNA G+C content, peptidoglycan type, menaquinone pattern, the presence of teichoic acid and cellular fatty acid composition were in agreement with the characteristics of species of the genus Staphylococcus. Sequencing of the 16S rRNA gene and four housekeeping genes (dnaJ, tuf, gap and rpoB) demonstrated that these strains constitute a separate taxon within the genus Staphylococcus. Less than 41% DNA-DNA hybridization with the most closely related species of the genus Staphylococcus (Staphylococcus haemolyticus, Staphylococcus hominis and Staphlococcus lugdunensis) was observed. Key biochemical characteristics that allowed these bacteria to be distinguished from their nearest phylogenetic neighbours are arginine dihydrolase positivity, ornithine decarboxylase negativity and inability to produce acid aerobically from D-mannose, α-lactose and turanose. Acid is produced aerobically from trehalose. Based on these results, a novel species of the genus Staphylococcus is described and named Staphylococcus jettensis sp. nov. The type strain is SEQ110(T) ( =LMG 26879(T) =CCUG 62657(T) =DSM 26618(T)).

The sink as a potential source of transmission of carbapenemase-producing Enterobacteriaceae in the intensive care unit

BackgroundCarbapenemase-producing Enterobacteriaceae (CPE) are emerging pathogens that represent a major public health threat. In the University Hospital of Brussels, the incidence of new patients with CPE rose from 1 case in 2010 to 35 cases in 2015. Between January and August 2015, five patients became infected/colonized with CPE during their stay in the same room in the intensive care unit (ICU). Since the time period between those patients was relatively short and the strains belonged to different species with different antibiograms and mechanisms of resistance, the hypothesis was that the environment could be a possible source of transmission.Methods and resultsEnvironmental samples suggested that a contaminated sink was the source of the outbreak. Besides other strains, Citrobacter freundii type OXA-48 was frequently isolated from patients and sinks. To investigate the phylogenetic relationschip between those strains, pulsed-field gel electrophoresis was performed. The strains isolated from patients and the sink in the implicated room were highly related and pointed to sink-to-patient transmission. In total, 7 of 8 sinks in the isolation rooms of the ICU were found to be CPE contaminated. To control the outbreak, the sinks and their plumbings were replaced by new ones with another structure, they were flushed every morning with a glucoprotamin solution and routines regarding sink practices were improved leading to discontinuation of the outbreak.ConclusionsThis outbreak highlights that hospital sink drains can accumulate strains with resistance genes and become a potential source of CPE.

In vitro activity of ertapenem against anaerobes isolated from the respiratory tract.

Ertapenem is a novel parenteral carbapenem with a long serum half-life. Its spectrum of activity is similar to that of imipenem and meropenem against Gram-positive bacteria, Enterobacteriaceae and fastidious Gram-negative bacteria but it is less active against Pseudomonas aeruginosa and Acinetobacter spp. Several studies were performed in the United States but only one European study has shown that ertapenem has an excellent activity against anaerobes. The objectives of the present study were to test the activity of ertapenem against anaerobes isolated prospectively from the lower and upper respiratory tracts, and to compare their susceptibility with that of anaerobic isolates from other body sites. Fifty-three isolates from the respiratory tract, as well as 50 isolates from various other body sites were tested with E-tests against six antibiotics. For respiratory isolates and for isolates from other sites, MIC 90 values (mg/l) were, respectively, >32 and >32 for penicillin, 0.38 and 0.75 for amoxicillin/clavulanate, 48 and >256 for ceftriaxone, 0.12 and 0.75 for ertapenem, 12 and >256 for clindamycin and 2 and 12 for moxifloxacin. The higher susceptibility of respiratory tract isolates was mainly due to the different distribution of isolated species: only three respiratory isolates but 22 other isolates belonged to the Bacteroides fragilis group. This study confirms the excellent anti-anaerobic activity of ertapenem against anaerobic isolates from the respiratory tract.