Hidemasa Nakaminami

Background Hidradenitis suppurativa (HS) is a chronic, inflammatory, recurrent, and debilitating skin disease. GAP Statement In Japan, the skin flora of the affected areas of patients with HS has not been fully investigated. Aim This study investigated bacterial species isolated from HS lesions and evaluated their antimicrobial susceptibility. Methodology A total of 47 strains isolated from 18 patients with HS at the Toranomon Hospital Dermatology Department were used. Bacterial species were identified using 16S rDNA gene analysis. Results As a result, coagulase-negative staphylococci were the most frequently isolated species, followed by several other bacteria, including Streptococcus spp., Corynebacterium spp., Cutibacterium spp., Pseudomonas aeruginosa, Bacteroides fragilis, Peptoniphilus coxii, and Peptoniphilus harei/asaccharolyticus. We evaluated the susceptibility of these isolates to various antimicrobial agents. All the strains were highly susceptible to fusidic acid and rifampicin. No resistance to fusidic acid was observed among the bacterial groups for which a resistance breakpoint was available. In contrast, Staphylococcus spp., Enterococcus spp., Corynebacterium spp., and Streptococcus spp. exhibited high rates of resistance to tetracyclines and macrolides. Detection of antimicrobial resistance genes in these strains revealed that 100% of Corynebacterium spp. carried erm(X), 60.0% of Streptococcus spp. carried erm(B), and 60.0% of coagulase-negative staphylococci strains carried erm(C). Additionally, 80.0% of Streptococcus spp. and 50.0% of Enterococcus spp. carried the tet(K). Conclusions Our findings show that bacteria isolated from patients with HS have a high frequency of indigenous bacteria that are resistant to antimicrobial agents. These results highlight the importance of appropriate antimicrobial agents for the treatment of patients with HS.

Since its emergence in the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has been recognized worldwide as a major cause of healthcare-associated infections. Traditionally, healthcare-associated MRSA (HA-MRSA) has been characterized as multidrug-resistant strains carrying staphylococcal cassette chromosome (SCC) mec types I–III, whereas community-associated MRSA (CA-MRSA) has been characterized as strains carrying SCCmec types IV or V that remain relatively susceptible to non-β-lactam antimicrobial agents. However, in recent years, the distinction between these two categories has become increasingly blurred owing to the global replacement of predominant clones, with community-associated clones entering healthcare settings and healthcare-associated clones spreading into the community. This review summarizes the epidemiology of MRSA in North America, South America, Europe, Africa, the Middle East, Asia, Oceania, and Japan and highlights the characteristics of the major circulating clones and their antimicrobial resistance profiles. Although the proportion of MRSA among S. aureus isolates has declined in many high-income countries owing to improvements in infection prevention and control, high isolation rates continue to be reported in Asia, the Middle East, and Africa. From a molecular epidemiological perspective, classical healthcare-associated clones, including ST239, ST5-II, and ST228-I, are declining, whereas SCCmec type IV clones, such as EMRSA-15 (ST22-IV), USA300 (ST8-IV), the Asian-Pacific clone (ST59-IV), and Queensland CA-MRSA (ST93-IV), are becoming predominant worldwide. In addition, although CA-MRSA has traditionally been considered susceptible to non-β-lactam antimicrobial agents, several clones have acquired multidrug resistance or novel resistance mechanisms. Moreover, with the widespread adoption of whole-genome sequencing (WGS), it has become possible to investigate the evolution of circulating clones, the acquisition of virulence factors and antimicrobial resistance genes, and even international transmission pathways at high resolution. Continued monitoring of regional molecular epidemiological characteristics, together with WGS-based international surveillance, will contribute to improved control of MRSA infections, optimization of infection prevention and control strategies, more appropriate empirical antimicrobial therapy, and the development of novel diagnostic and therapeutic approaches.

Panton – Valentine leukocidin (PVL) is a leukocyte-lytic toxin produced by Staphylococcus aureus , which is primarily associated with skin and soft tissue infections. Notably, there has been an increase in the number of cases caused by the USA300 lineage in Japan. However, the reported prevalence of USA300 is limited in other Asian countries, including Korea. This study investigated the prevalence of PVL-positive methicillin-resistant S. aureus (MRSA) in Korea and Japan and compared their molecular epidemiological characteristics. A total of 463 MRSA strains were analyzed, comprising 283 strains from patients visiting two hospitals in Seongnam and Seoul, Korea, and 180 strains from six hospitals in Tokyo, Japan, between 2018 and 2019. The PVL-encoding genes lukS/F-PV were detected using PCR. Molecular epidemiological and phylogenetic analyses were performed using next-generation sequencing. Overall, 27 (9.5%) PVL-positive MRSA strains were detected among strains isolated from Korea, and 16 (8.9%) were detected among those isolated from Japan. Genotyping of PVL-positive strains revealed that 85.2% of Korean and 81.3% of Japanese strains belonged to USA300. Most USA300 strains from Japan and Korea formed distinct clusters in phylogenetic analyses. Meanwhile, ΨUSA300 and ST22-PT, clones that are prevalent in Japan, were isolated in Korea. This study showed that USA300 strains, which are becoming more prevalent in Japan, are also present in Korea. Furthermore, this study suggests that ΨUSA300 and ST22-PT may be spreading between these two countries. Therefore, it is necessary to continue monitoring the epidemiological trends of PVL-positive MRSA clones both domestically and internationally. IMPORTANCE: Panton–Valentine leukocidin (PVL) is a major toxin produced by Staphylococcus aureus . Although a rapid increase in PVL-positive strains has been reported in Japan, data on PVL-positive strains in Korea remain limited. In this study, we performed a comparative analysis of PVL-positive S. aureus isolates from Korea and Japan. The results showed that the clinical backgrounds and genetic profiles of PVL-positive strains isolated in Korea and Japan were highly similar. Furthermore, we confirmed for the first time that clones circulating in Japan, including ΨUSA300 and ST22-PT, were also isolated in Korea. These findings provide valuable insights into the epidemiological status of PVL-positive S. aureus in East Asia.

Background Hidradenitis suppurativa (HS) is a chronic, inflammatory, recurrent, and debilitating skin disease. GAP Statement In Japan, the skin flora of the affected areas of patients with HS has not been fully investigated. Aim This study investigated bacterial species isolated from HS lesions and evaluated their antimicrobial susceptibility. Methodology A total of 47 strains isolated from 18 patients with HS at the Toranomon Hospital Dermatology Department were used. Bacterial species were identified using 16S rDNA gene analysis. Results As a result, coagulase-negative staphylococci were the most frequently isolated species, followed by several other bacteria, including Streptococcus spp., Corynebacterium spp., Cutibacterium spp., Pseudomonas aeruginosa, Bacteroides fragilis, Peptoniphilus coxii, and Peptoniphilus harei/asaccharolyticus. We evaluated the susceptibility of these isolates to various antimicrobial agents. All the strains were highly susceptible to fusidic acid and rifampicin. In contrast, Staphylococcus spp., Enterococcus spp., Corynebacterium spp., and Streptococcus spp. exhibited high rates of resistance to tetracyclines and macrolides. Detection of antimicrobial resistance genes in these strains revealed that 100% of Corynebacterium spp. carried erm(X), 60.0% of Streptococcus spp. carried erm(B), and 60.0% of coagulase-negative staphylococci strains carried erm(C). Additionally, 80.0% of Streptococcus spp. and 50.0% of Enterococcus spp. carried the tet(K). Conclusions Our findings show that bacteria isolated from patients with HS have a high frequency of indigenous bacteria that are resistant to antimicrobial agents. These results highlight the importance of appropriate antimicrobial agents for the treatment of patients with HS.

Background Hidradenitis suppurativa (HS) is a chronic, inflammatory, recurrent, and debilitating skin disease. GAP Statement In Japan, the skin flora of the affected areas of patients with HS has not been fully investigated. Aim This study investigated bacterial species isolated from HS lesions and evaluated their antimicrobial susceptibility. Methodology A total of 47 strains isolated from 18 patients with HS at the Toranomon Hospital Dermatology Department were used. Bacterial species were identified using 16S rDNA gene analysis. Results As a result, coagulase-negative staphylococci were the most frequently isolated species, followed by several other bacteria, including Streptococcus spp., Corynebacterium spp., Cutibacterium spp., Pseudomonas aeruginosa, Bacteroides fragilis, Peptoniphilus coxii, and Peptoniphilus harei/asaccharolyticus. We evaluated the susceptibility of these isolates to various antimicrobial agents. All the strains were highly susceptible to fusidic acid and rifampicin. In contrast, Staphylococcus spp., Enterococcus spp., Corynebacterium spp., and Streptococcus spp. exhibited high rates of resistance to tetracyclines and macrolides. Detection of antimicrobial resistance genes in these strains revealed that 100% of Corynebacterium spp. carried erm(X), 60.0% of Streptococcus spp. carried erm(B), and 60.0% of coagulase-negative staphylococci strains carried erm(C). Additionally, 80.0% of Streptococcus spp. and 50.0% of Enterococcus spp. carried the tet(K). Conclusions Our findings show that bacteria isolated from patients with HS have a high frequency of indigenous bacteria that are resistant to antimicrobial agents. These results highlight the importance of appropriate antimicrobial agents for the treatment of patients with HS.

Background and objectives: Cutibacterium species, including Cutibacterium avidum, Cutibacterium granulosum and Cutibacterium acnes are commensal skin bacteria. The latter exacerbates acne vulgaris. In the past decades, high antimicrobial use for the treatment of acne has led to the spread of macrolide- and lincosamide-resistant, particularly clindamycin-resistant, strains. C. avidum has been reported to show higher resistance rates than C. acnes. The known mechanisms of macrolide resistance in Cutibacterium species includes either mutations in 23S rRNA encoding gene or the acquisition of methyltransferase genes, such as erm(X) and erm(50). This study analysed the resistance mechanisms of C. avidum, a commensal skin species that is occasionally isolated from acne lesions. This study focused on strains lacking known macrolide–lincosamide resistance determinants. Methods: The antimicrobial susceptibility of 50 C. avidum strains isolated from facial acne pustules between 2013 and 2020 was evaluated by determining MIC values. Whole-genome sequencing was used to identify the putative resistance factors. The candidate gene was cloned into Escherichia coli for functional analysis, and its amino acid sequence was compared with that of previously reported Erm proteins. Results: Approximately 90% of C. avidum strains exhibited resistance to macrolides and clindamycin. Two of these strains lacked known resistance factors. Whole-genome sequence analysis revealed the presence of a methyltransferase-encoding gene. Introducing this gene into E. coli conferred resistance to macrolides, confirming its function. The protein with the highest similarity to Erm(38), but <79% identity, was therefore designated as Erm(57). Unlike erm(X) and erm(50), erm(57) was not transmitted horizontally. Conclusions: This study identified erm(57) as a novel non-transmissible macrolide–lincosamide resistance gene in C. avidum.