Isolation of azole-resistant Aspergillus spp. from food products.

The prevalence of azole-resistant Aspergillus fumigatus is increasing worldwide and is speculated to be related to the use of azole pesticides. Aspergillus spp., the causative agent of aspergillosis, could be brought into domestic dwellings through food. However, studies on azole-resistant Aspergillus spp. in food products are limited. Therefore, we aimed to isolate Aspergillus spp. from processed foods and commercial agricultural products and performed drug susceptibility tests for azoles. Among 692 food samples, we isolated 99 strains of Aspergillus spp. from 50 food samples, including vegetables (22.9%), citrus fruits (26.3%), cereals (25.5%), and processed foods (1.8%). The isolates belonged to 18 species across eight sections: Aspergillus, Candidi, Clavati, Flavi, Fumigati, Nidulantes, Nigri, and Terrei. The most frequently isolated section was Fumigati with 39 strains, followed by Nigri with 28 strains. Aspergillus fumigatus and A. welwitschiae were the predominant species. Ten A. fumigatus and four cryptic strains, four A. niger cryptic strains, two A. flavus, and four A. terreus strains exceeded epidemiological cutoff values for azoles. Aspergillus tubingensis, A. pseudoviridinutans, A. lentulus, A. terreus, and N. hiratsukae showed low susceptibility to multi-azoles. Foods containing agricultural products were found to be contaminated with Aspergillus spp., with 65.3% of isolates having minimal inhibitory concentrations below epidemiological cutoff values. Additionally, some samples harbored azole-resistant strains of Aspergillus spp. Our study serves as a basis for elucidating the relationship between food, environment, and clinically important Aspergillus spp.

Emergence of Phytobacter diazotrophicus carrying an IncA/C2 plasmid harboring bla NDM-1 in Tokyo, Japan.

Phytobacter diazotrophicus is an Enterobacterales species that was originally identified as a plant growth-promoting, Gram-negative bacterium. Recently, this species has been recognized as relevant to opportunistic human and nosocomial infections in clinical settings. Its frequent misidentification as other Enterobacterales species from clinical examination occasionally causes a delay in the identification of nosocomial outbreaks. Here, we report the emergence of New Delhi metallo-ß-lactamase (NDM)-producing P. diazotrophicus isolated from hospitalized pediatric patients and hospital environments in Tokyo, Japan. In our case, these isolates were found during an investigation of carbapenem-resistant Enterobacterales in relation to nosocomial infections. Whole-genome sequencing is useful for overcoming the difficulty of species identification. Furthermore, we found that bla NDM-1 was carried by an IncA/C2 plasmid (approximately 170 kbp), which was transferrable from the clinical isolates to the recipient strain Escherichia coli J53. Our study demonstrated that P. diazotrophicus behaves as a carrier of bla NDM-harboring plasmids, potentially disseminating resistance to carbapenems among Enterobacterales. IMPORTANCE Early detection of nosocomial outbreaks is important to minimize the spread of bacteria. When an outbreak is caused by multidrug-resistant bacteria such as carbapenem-resistant Enterobacterales, a delay in findings makes it difficult to control it because such bacteria often spread not only among human patients but also in hospital environments. Phytobacter diazotrophicus, an Enterobacterales species that has recently been found to be relevant to clinical settings, is often misidentified as other bacteria in clinical laboratories. Here, we found NDM-producing P. diazotrophicus in hospitalized pediatric patients and their environment in Tokyo, Japan. Given that the isolates carried bla NDM-1-harboring transferrable plasmids, the influence of such bacteria could be greater with the mediation of horizontal transfer of carbapenem resistance. Our findings suggest that P. diazotrophicus should be recognized as an NDM-carrier, for which more attention should be paid in clinical settings.

Rapid identification of histamine-producing bacteria isolated from fish using MALDI-TOF MS.

Histamine-producing bacteria (HPB) produce histamine from histidine contained in food through the action of histidine decarboxylase. To identify HPB isolated from food, it is necessary to detect histamine produced by the bacteria. In this study, we concurrently identified HPB and detected histamine by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. After 24 h of incubation, 30 of 34 bacterial strains were correctly identified. Histamine was detected in all HPB cultured on Niven's medium, and 94% of HPB cultured in histidine broth, except for two strains with low histamine production. This method may greatly simplify the procedure and reduce the time required to identify HPB.

Eldecalcitol increases bone mineral density in Chinese osteoporotic patients without vitamin D or calcium supplementation.

Eldecalcitol increased bone mineral density (BMD) and prevented vertebral fractures in vitamin D-sufficient osteoporotic subjects. However, the effect of eldecalcitol on BMD under vitamin D insufficiency is unknown. We examined the effect of eldecalcitol on BMD compared with alfacalcidol in osteoporotic patients without vitamin D or calcium supplementation. This is a randomized, double-blind, active comparator trial. 265 Chinese osteoporotic patients were randomly assigned to receive 0.75 µg eldecalcitol or 1.0 µg alfacalcidol for 12 months without vitamin D or calcium supplementation. Baseline calcium intakes were less than 550 mg/day and mean serum 25-hydroxyvitamin D [25(OH)D] was below 43 nmol/L in both groups. Baseline BMD tended to be lower in patients with lower calcium intake and serum 25(OH)D. Lumbar BMD increased by 2.05% higher in eldecalcitol than alfacalcidol group at 12 months. Total hip and femoral neck BMD also increased by 1.33 and 1.78%, respectively, in the eldecalcitol than the alfacalcidol group. The effect of eldecalcitol on BMD was not affected by serum 25(OH)D or calcium intake. The incidence of adverse events was not different between the two groups. Incidence of hypercalcemia in the edecalcitol group was not affected by serum 25(OH)D. In conclusion, baseline BMD tended to be lower in patients with low calcium intake and serum 25(OH)D. Eldecalcitol increased lumbar and hip BMD more than alfacalcidol regardless of serum 25(OH)D or calcium intake without vitamin D or calcium supplementation. These results suggest that eldecalcitol is effective in increasing the BMD of osteoporotic patients regardless of vitamin D status or calcium intake.Clinical Trial Registration number JAPIC CTI 152904.

Distribution of Sterigmatocystin-producing Aspergilli in Japan.

Sterigmatocystin is a genotoxic and hepatocarcinogenic mycotoxin that contaminates foods and environments worldwide. Sterigmatocystin is produced as a precursor to aflatoxin B1 or as an end product by certain Aspergilli. Aspergillus section Versicolores is one of the major sections including sterigmatocystin-producing species and is thus a potential health and environmental hazard. Recently, the taxonomy of this section was revised and classified into 14 species on the basis of molecular phylogenetic analysis. However, investigation of the distribution and sterigmatocystin production of each species has been limited; in particular, its distribution in foods has been scarcely reported. In this study, we collected isolates of Aspergillus section Versicolores from various foods and environments in Japan and investigated their distribution and sterigmatocystin production. The isolates were classified into nine species or species groups, which revealed that A. creber, A. puulaauensis/tennesseensis and A. sydowii are the main species/species groups in Japan. In addition, A. versicolor sensu stricto was detected with some frequency, specifically in foods. Furthermore, the two species A. creber and A. versicolor sensu stricto frequently produced sterigmatocystin. It is therefore important for food safety to intensively monitor these two species and distinguish them from other species, especially A. sydowii, which is not considered to produce sterigmatocystin.

Detection of the staphylococcal enterotoxin D-like gene from staphylococcal food poisoning isolates over the last two decades in Tokyo.

The plasmid is a very well-known mobile genetic element that participates in the acquisition of virulence genes, such as staphylococcal enterotoxins (SEs), via horizontal transfer. SEs are emetic toxins and causative agents in staphylococcal food poisoning (SFP). We herein identified the types of plasmids harbored by seven SFP isolates and examined their production of plasmid-related SE/SEl to determine whether the new types of plasmid-related SE or SE-like (SEl) toxins (i.e. SElJ and SER) were involved in SFP. These isolates harbored pIB485-like plasmids, and all, except for one isolate, produced SElJ and SER. The amount of SER produced by each isolate accounted for the highest or second highest percentage of the total amount of SE/SEl produced. These new types of plasmid-related SE/SEls as well as classical SE may play a role in SFP. The seven isolates were classified into two SED-production types; a high SED-production type (>500 ng/ml) and no SED-production type. A nucleotide sequencing analysis revealed that three plasmids harbored by the SED-non-producing isolates had a single-base deletion in the sed gene with a resulting stop codon (from 233 amino acids of the intact SED to 154 amino acids of the mutant SED (mSED)). A real-time reverse transcription-PCR analysis showed that the mRNA of the msed gene was transcribed in the isolates. If the msed gene was translated as a protein, mSED may act as an emetic toxin instead of intact SED.