Vancomycin-intermediately resistant Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) are associated with treatment failure. hVISA contains only a subpopulation of cells with increased minimal inhibitory concentrations, and its detection is problematic because it is classified as vancomycin-susceptible by standard susceptibility testing and the gold-standard method for its detection is impractical in clinical microbiology laboratories. Recently, a research group developed a machine-learning classifier to distinguish VISA and hVISA from vancomycin-susceptible S. aureus (VSSA) according to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) data. Nonetheless, the sensitivity of hVISA classification was found to be 76%, and the program was not completely automated with a graphical user interface. Here, we developed a more accurate machine-learning classifier for discrimination of hVISA from VSSA and VISA among MRSA isolates in Japanese hospitals by means of MALDI-TOF MS data. The classifier showed 99% sensitivity of hVISA classification. Furthermore, we clarified the procedures for preparing samples and obtaining MALDI-TOF MS data and developed all-in-one software, hVISA Classifier, with a graphical user interface that automates the classification and is easy for medical workers to use; it is publicly available at https://github.com/bioprojects/hVISAclassifier. This system is useful and practical for screening MRSA isolates for the hVISA phenotype in clinical microbiology laboratories and thus should improve treatment of MRSA infections.

We previously reported a novel phenotype of vancomycin-intermediate Staphylococcus aureus (VISA), i.e., “slow VISA,” whose colonies appear only after 72 h of incubation. Slow-VISA strains can be difficult to detect because prolonged incubation is required and the phenotype is unstable. To develop a method for detection of slow-VISA isolates, we studied 23 slow-VISA isolates derived from the heterogeneous VISA (hVISA) clinical strain Mu3. We identified single nucleotide polymorphisms (SNPs) in genes involved in various pathways which have been implicated in the stringent response, such as purine/pyrimidine synthesis, cell metabolism, and cell wall peptidoglycan synthesis. We found that mupirocin, which also induces the stringent response, caused stable expression of vancomycin resistance. On the basis of these results, we developed a method for detection of slow-VISA strains by use of 0.032 μg/ml mupirocin (Yuki Katayama, 7 March 2017, patent application PCT/JP2017/008975). Using this method, we detected 53 (15.6%) slow-VISA isolates among clinical methicillin-resistant S. aureus (MRSA) isolates. In contrast, the VISA phenotype was detected in fewer than 1% of isolates. Deep-sequencing analysis showed that slow-VISA clones are present in small numbers among hVISA isolates and proliferate in the presence of vancomycin. This slow-VISA subpopulation may account in part for the recurrence and persistence of MRSA infection.

Antimicrobial resistance (AMR) is a global threat to human health. Education on antibiotics is essential for AMR prevention, and training should be provided for undergraduate pharmacy students.

To improve the COVID-19 vaccination rate, it is necessary for medical professionals to provide appropriate information about the vaccination to the public. In the present study, to clarify the relationship between pharmacist opinions about providing information on COVID-19 vaccination, and the occurrence of adverse reactions with the vaccination, questionnaire surveys for pharmacists vaccinated against COVID-19 were performed. Pharmacist opinions were analyzed by Berelsonʼs content analysis. A total of 216 valid questionnaires were collected. The number of pharmacists that had trepidation about the vaccination was 59.0％ (1st dose) and 60.6％ (2nd dose), respectively, and the safety of the vaccine was the most common reason for the response. Pain at the injection site was the most common adverse reaction with the vaccination. The incidence of headache, chills, fever, and joint pain increased on the 2nd dose compared to the 1st. The most common pharmacist opinion was about adverse reactions of the vaccine. These results suggest that pharmacists, as medical professionals felt apprehensive through the experience of adverse reactions, or gathering information about the vaccine. We could clarify the pharmacist opinion that it is important to provide information about adverse reactions for promoting the COVID-19 vaccination. Thus, we hope that pharmacists can dispel general public anxiety over the COVID-19 vaccination by providing accurate information of adverse reactions, such as those that are likely to occur in each dose, the timing of their occurrence, how to deal with adverse reactions, and that this then leads to promoting the publicʼs uptake of the COVID-19 vaccination.