The microbiome of the reproductive tract has been associated with (sub)fertility and it has been suggested that dysbiosis reduces success rates and pregnancy outcomes. The endometrial microbiome is of particular interest given the potential impact on the embryo implantation. To date, all endometrial microbiome studies have applied a metagenomics approach. A sequencing-based technique, however, has its limitations, more specifically in adequately exploring low-biomass settings, such as intra-uterine/endometrial samples. In this proof-of-concept study, we demonstrate the applicability of culturomics, a high-throughput culturing approach, to investigate the endometrial microbiome. Ten subfertile women undergoing diagnostic hysteroscopy and endometrial biopsy, as part of their routine work-up at Brussels IVF, were included after their informed consent. Biopsies were used to culture microbiota for up to 30 days in multiple aerobic and anaerobic conditions. Subsequent WASPLab®-assisted culturomics enabled a standardized methodology. Matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI-TOF MS) or 16S rRNA sequencing was applied to identify all of bacterial and fungal isolates. Eighty-three bacterial and two fungal species were identified. The detected species were in concordance with previously published metagenomics-based endometrial microbiota analyses as 77 (91%) of them belonged to previously described genera. Nevertheless, highlighting the added value of culturomics to identify most isolates at the species level, 53 (62.4%) of the identified species were described in the endometrial microbiota for the first time. This study shows the applicability and added value of WASPLab®-assisted culturomics to investigate the low biomass endometrial microbiome at a species level.

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The susceptibility of 389 Enterobacteriaceae, 231 other Gram-negative bacilli (including 150 Pseudomonas aeruginosa) and 233 Gram-positive organisms was determined by the NCCLS reference microdilution technique against cefpirome and other antibiotics. Cefpirome and cefepime were the most active compounds against Enterobacteriaceae, including potentially beta-lactamase-inducible species. The MIC90 of cefpirome against potentially inducible and non-inducible species of Enterobacteriaceae was 2 mg/L and 0.5 mg/L, respectively. Ceftazidime, cefpirome and cefepime had similar activity against P. aeruginosa, with MIC90s of 64 mg/L, 64 mg/L and 32 mg/L, respectively. Cefpirome and cefepime had similar activity against Gram-positive cocci, with MIC90s of 1 mg/L and 2 mg/L, respectively, against oxacillin-susceptible Staphylococcus aureus and 64 mg/L and 128 mg/L, respectively, against Enterococcus spp.; both had an MIC90 of 1 mg/L against Streptococcus pneumoniae. This study shows that fourth-generation cephalosporins, such as cefpirome, could be useful in haematology/oncology units and, in particular, ICUs where high resistance rates are observed.