Infectious diseases caused by antibiotic-resistant bacteria has greatly increased and brought a recent public health crisis worldwide. Therefore, it is requisite to develop new antibiotics with a novel pharmacophore or molecular target. In this review, chemistry and antimicrobial properties of new microbial metabolites, tumescenamide C, chlorocatechelins, and saccharothriolides, as pharmaceutical leads produced by actinomycetes such as Streptomyes sp. and the rare actinomycete Saccharothrix sp. are summarized. In addition, precursor-directed in situ synthesis (PDSS) to obtain new derivatives of microbial metabolites in one pot is also described.

The activities of antibacterial agents against aerobic Gram-positive cocci (31 genus or species, 1,020 strains in 2010, 992 strains in 2012) and anaerobic bacteria (23 genus or species, 178 strains in 2010, 211 strains in 2012) isolated from clinical specimens in 2010 and 2012 at clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratios of methicillin-resistant Staphylococcus aureus (MRSA) isolates to all S. aureus were 54.2% in 2010 and 51.4% in 2012. Those of methicillin-resistant Staphylococcus epidermidis (MRSE) isolates to all S. epidermidis were 82.5% in 2010 and 84.9% in 2012. The prevalence rates of these resistant strains maintained similar levels after the surveillance study started in 1992. Against these methicillin-resistant strains, vancomycin (VCM) showed good antibacterial activity with the MIC₉₀s of ≤2 μg/mL in 2010 and 2012. The ratios of genotypic penicillinsusceptible Streptococcus pneumoniae isolates increased to 20.4% in 2012 after the decline from 2002 to 2010. Against all the strains of Enterococcus faecalis and Enterococcus faecium, VCM and teicoplanin showed good activities with the MIC₉₀s of ≤2 μg/mL and no VCM-resistant strains was found in 2010 and 2012. The MIC₉₀s of linezolid were 2 and 4 μg/mL in 2010 and 2012, respectively, and the rates of non-susceptible strains reached more than 10%. Against Clostridium difficile, the MIC₉₀s of VCM were 1 μg/mL in 2010 and 2012, but there was a strain with the VCM MIC of 4 μg/mL in 2012. Carbapenems showed good activity against Bacteroides spp. and Prevotella spp. with MIC₉₀s of ≤2 μg/mL.

As the results of this study, there was no significant increase of highly resistant or multi-drug resistant strains among aerobic gram-positive cocci and anaerobic bacteria.

Tosoh TRC Ready MP is a newly developed automatic Mycoplasma pneumoniae rapid detection method using a transcription reverse-transcription concerted reaction. We analyzed the performance of the TRCReady MP assay by comparing with polymerase chain reaction (PCR) method and Loop mediated isothermal amplification (LAMP) method with clinical samples. As for the result of 290 clinical samples in which detection of M. pneumoniae was targeted, the rate of concordance between TRCReady MP and PCR method was 96.2% (sensitivity, 98.2%; specificity, 95.7%), and that between TRCReady and LAMP method was 96.2% (sensitivity, 100%; specificity, 95.3%). It takes within one hour for detection using TRCReady MP after sample preparation processing. These results indicate that TRCReady MP is useful for the rapid diagnosis of M. pneumoniae infection.

First-dose mumps vaccination at a younger age may be associated with a lower risk of vaccine-associated aseptic meningitis. However, to date, there are no estimates of the age-specific incidence of aseptic meningitis caused by the Torii strain-derived mumps vaccine. We investigated post-vaccination aseptic meningitis incidence in Japan using case data from the Ministry of Health, Labour and Welfare regarding adverse reactions following the Torii strain-derived mumps vaccine. The number of age-specific vaccine administrations was estimated from an Internet survey dataset and the number of vaccine shipments. Using these numbers, we estimated the age-specific post-vaccination aseptic meningitis incidence. Between April 1, 2013, and April 30, 2016, the incidence among first-dose vaccinations was 3.5 cases and the incidence among 1-year-old recipients was 1.3 cases (per 100,000 doses). Compared with the incidence at 1 year, significantly higher rates were observed at ages 2–6, 7–12, and ≥13 years. Our results suggest that vaccination with the Torii strain-derived mumps vaccine at age 1 carries a lower risk of aseptic meningitis compared with administration of this vaccine at older ages.

We retrospectively reviewed the susceptibility of bacterial pathogens isolated from blood cultures of pediatric febrile neutropenic patients during a 7-year period. In total, 66 microorganisms were isolated; 34 (32%) Gram-negative bacteria, 28 (42%) Gram-positive bacteria, and four others (6%). The most common Gram-negative isolates were members of the Enterobacteriaceae family (26 strains), followed by aerobic bacteria (four strains), and Pseudomonas aeruginosa (three strains). Among the Gram-positive bacteria, staphylococci constituted the mmajority (16 strains), followed by streptococci (six strains), enterococci (four strains), and Rothia mucilaginosa (two strains). The antibiotic susceptibilities of the Gram-negative bacteria to tazobactam/piperacilin, cefepime, meropenem, and levofloxacin were 88.2%. 94.1%, 97.1% and 83.3%, respectively. Two meropenem-resistant P. aeruginosa and one extended-spectrum β-lactamase-producing Klebsiella pneumoniae were also isolated. The antibiotic susceptibilities of the Gram-positive bacteria to vancomycin, teicoplanin, linezolid, and daptomycin were 96.2%, 64.3%, 88.0%, and 96.0%, respectively; the susceptibility to teicoplanin was significantly lower among coagulase-negative staphylococci because of reduced susceptibility.

Although most stains were sensitive to the empirical antibiotics for febrile neutropenia, some were resistant to these antibiotics, thereby indicating the need to use antibiotics empirically, according to the antibiograms and conditions of the patients with febrile neutropenia. The appropriate use of antibiotics to minimize antibiotic resistance is also very important.