A case of community-acquired pneumonia caused by Bacillus subtilis subsp. natto in an immunocompetent patient.

A 70-year-old immunocompetent male with a history of insomnia presented with pneumonia and bacteremia caused by Bacillus subtilis. The patient took benzodiazepines and regularly consumed alcohol and natto (fermented soybeans). Initial antibiotic treatment was not effective, and bronchoalveolar lavage was performed. Bronchoalveolar lavage fluid (BALF) analysis revealed an increased lymphocytes fraction, and B. subtilis was detected in the BALF. Whole-genome sequencing confirmed the congruence of the genetic sequences between the strain in the blood culture of the patient, BALF, and strain isolated from the consumed natto, confirming B. subtilis subsp. natto as the causative pathogen of pneumonia and bacteremia. Vancomycin followed by levofloxacin and systemic corticosteroid were used to treat the condition. This case highlights community-acquired pneumonia and bacteremia caused by B. subtilis subsp. natto, particularly in individuals who consume natto.

Outbreak of Streptococcus pyogenes emm89 ST646 in a head and neck surgical oncology ward.

Streptococcus pyogenes causes a variety of human infections, and hospital outbreaks with this pathogen have also been reported. The purpose of this study is to describe the clinical characteristics of an outbreak of S. pyogenes involving 15 patients and four healthcare workers (HCWs), as well as the molecular characteristics of the causative isolates. The course and response to the outbreak were reviewed, and information on the characteristics of the patients was extracted retrospectively from the medical records. Whole-genome sequencing of the 16 causative isolates (14 from patients and two from HCWs) was also performed. All 15 patients were postoperative of head and neck cancer with tracheotomy, and 12 had invasive infections, primarily surgical site infections, all of which resolved without causing serious illness. All but the first case was detected more than 7 days after admission. S. pyogenes was detected in two patients after empiric antimicrobial administration was performed on all inpatients and HCWs, and the outbreak was finally contained in approximately 2 months. All isolates detected in patients and HCWs belonged to emm89/clade 3, a hypervirulent clone that has emerged worldwide and was classified as sequence type 646. These isolates had single nucleotide polymorphism (SNP) differences of zero to one, indicating clonal transmission. This study demonstrated an outbreak of S. pyogenes emm89/clade 3 in a ward of patients with head and neck cancer. The global emergence of hypervirulent isolates may increase the risk of outbreaks among high-risk patients. IMPORTANCE: This study describes an outbreak of Streptococcus pyogenes that occurred in a ward caring for patients with head and neck cancer and tracheostomies. Many cases of invasive infections occurred in a short period, and extensive empiric antimicrobial administration on patients and healthcare workers was performed to control the outbreak. Whole-genome sequencing analysis of the causative strains confirmed that it was a monoclonal transmission of strains belonging to emm89/clade 3. The epidemiology and clinical characteristics of S. pyogenes infections have changed with the replacement of the prevalent clones worldwide. In the 1980s, there was a reemergence of S. pyogenes infections in high-income countries due to the spread of hypervirulent emm1 strains. emm89/clade 3 has recently been spreading worldwide and shares common features with emm1, including increased production of two toxins, NADase, and streptolysin O. The outbreak reported here may reflect the high spreading potential and virulence of emm89/clade 3.

The outbreak of multispecies carbapenemase-producing Enterobacterales associated with pediatric ward sinks: IncM1 plasmids act as vehicles for cross-species transmission.

BACKGROUND: This study describes an outbreak caused by multispecies carbapenemase-producing Enterobacterales (CPE) occurring in a pediatric ward at an academic medical center in Tokyo. METHODS: The index case involved a 1-year-old boy with Klebsiella variicola (CPE) detected in anal swabs in June 2016. The second case was Klebsiella quasipneumoniae (CPE) occurred in March 2017 followed by further spread, leading to the declaration of an outbreak in April 2017. Extensive environmental and patient microbiological sampling was performed. The relatedness of the isolates was determined using draft-whole-genome sequencing. RESULTS: CPE surveillance cultures of patients and environments were positive in 19 patients and 9 sinks in the ward. The sinks in hospital rooms uninhabited by CPE patients exhibited no positive CPE-positive specimen during the outbreak. All CPE strains analyzed using draft-whole-genome sequencing harbored blaIMP-1, except for one harboring blaIMP-11; these strains harbored identical blaIMP-1-carrying IncM1 plasmids. CPE was detected even after sink replacement; infection-control measures focused on sinks were implemented and the CPE outbreak ended after 7 months. CONCLUSIONS: Multiple bacterial species can become CPE via blaIMP-1-carrying IncM1 plasmids of the same origin and spread through sinks in a hospital ward. Thorough infection-control measures implemented as a bundle might be crucial.

Assessing the discriminability of PCR-based open reading frame typing versus single-nucleotide polymorphism analysis via draft whole-genome sequencing of methicillin-resistant Staphylococcus aureus in nosocomial transmission analysis.

Phylogenetic analysis based on single-nucleotide polymorphism (SNP)-based through whole-genome sequencing is recognized as the standard method for probing nosocomial transmission. However, the application of WGS is constrained by the high cost of equipment and the need for diverse analysis tools, which limits its widespread use in clinical laboratory settings. In Japan, the prevalent use of PCR-based open reading frame typing (POT) for tracing methicillin-resistant Staphylococcus aureus (MRSA) transmission routes is attributed to its simplicity and ease of use. Although POT's discriminatory power is considered insufficient for nosocomial transmission analysis, conclusive data supporting this notion is lacking. This study assessed the discriminatory capabilities of SNP analysis and POT across 64 clinical MRSA strains. All 21 MRSA strains of ST5/SCCmec IIa, having more than 16 SNPs, demonstrated distinct clones. Conversely, two strains shared the same POT number and were identified as group A. Among the 12 MRSA strains of ST8/SCCmec IVl with over nine SNPs, five fell into POT group B, and five into POT group C. All four MRSA strains of ST8/SCCmec IVa were classified into POT group D, although they included strains with more than 30 SNPs. Among the 27 MRSA strains of ST1/SCCmec IVa, 14 were classified into POT group E. However, except for two clusters (each comprising two or three strains), all had SNP counts >10 (Fig. 1-D). SNP analysis of MRSA in CC1/SCCmec IV showed that several strains had the same number of SNPs in POT number (106-183-37), even among bacteria with >100 SNPs, indicating POT's limited use in detailed nosocomial transmission analysis.

Molecular epidemiological and antimicrobial-resistant mechanisms analysis of prolonged Neisseria gonorrhoeae collection between 1971 and 2005 in Japan.

Objectives: As antimicrobial-resistant (AMR) Neisseria gonorrhoeae strains have emerged, humans have adjusted the antimicrobials used to treat infections. We identified shifts in the N. gonorrhoeae population and the determinants of AMR strains isolated during the recurring emergence of resistant strains and changes in antimicrobial therapies. Methods: We examined 243 N. gonorrhoeae strains corrected at the Kanagawa Prefectural Institute of Public Health, Kanagawa, Japan, these isolated in 1971-2005. We performed multilocus sequence typing and AMR determinants (penA, mtrR, porB, ponA, 23S rRNA, gyrA and parC) mainly using high-throughput genotyping methods together with draft whole-genome sequencing on the MiSeq (Illumina) platform. Results: All 243 strains were divided into 83 STs. ST1901 (n = 17) was predominant and first identified after 2001. Forty-two STs were isolated in the 1970s, 34 in the 1980s, 22 in the 1990s and 13 in the 2000s, indicating a decline in ST diversity over these decades. Among the 29 strains isolated after 2001, 28 were highly resistant to ciprofloxacin (MIC ≥ 8 mg/L) with two or more amino-acid substitutions in quinolone-resistance-determining regions. Seven strains belonging to ST7363 (n = 3), ST1596 (n = 3) and ST1901 (n = 1) were not susceptible to cefixime, and six strains carried penA alleles with mosaic-like penicillin-binding protein 2 (PBP2; penA 10.001 and 10.016) or PBP2 substitutions A501V and A517G. Conclusions: We observed a significant reduction in the diversity of N. gonorrhoeae over 35 years in Japan. Since 2001, ST1901, which is resistant to ciprofloxacin, has superseded previous strains, becoming the predominant ST population.

Evolutionary dynamics of the novel ST22-PT methicillin-resistant Staphylococcus aureus clone co-harbouring Panton-Valentine leucocidin and duplicated toxic shock syndrome toxin 1 genes.

OBJECTIVES: Globally, the isolation of community-associated methicillin-resistant Staphylococcus aureus (MRSA) harbouring both the Panton-Valentine leucocidin (PVL) and toxic shock syndrome toxin 1 (TSST-1) genes is rare. However, we encountered an outbreak of the ST22-PT clone exhibiting this phenotype in Japan. Notably, the TSST-1 gene was duplicated in most of the strains. This study aimed to elucidate the mechanisms underlying this gene duplication. METHODS: A total of 90 MRSA isolates were collected from the skin of outpatients in Fukuoka City, Japan, between 2017 and 2019. Whole-genome sequencing was performed on MRSA strains that were PVL and TSST-1 positive. RESULTS: A total of 43 (47.8%) strains produced TSST-1, 20 (22.2%) produced PVL, and 16 (17.8%) produced both. Fifteen isolates were classified as ST22/SCCmec type IVa (ST22-PT clone) and one as ST1/SCCmec type V (ST1-PT clone). Three distinct ST22-PT clones were identified: Fukuoka clone I (one PVL gene and one TSST-1 gene), Fukuoka clone II (addition of a TSST-1 gene to Fukuoka clone I), and Fukuoka clone III (marked by a chromosomal inversion in a large region from Fukuoka clone II). DISCUSSION: Fukuoka clone I may have integrated a novel pathogenicity island bearing the TSST-1 gene, leading to the emergence of Fukuoka clone II with a duplicated TSST-1 gene. This duplication subsequently instigated a chromosomal inversion in a large region owing to the homologous sequence surrounding TSST-1, giving rise to Fukuoka clone III. These findings provide crucial insights into the genetic evolution of MRSA.

Analysis of the stepwise acquisition of blaCTX-M-2 and subsequent acquisition of either blaIMP-1 or blaIMP-6 in highly conserved IncN-pST5 plasmids.

Objectives: ESBL and carbapenemase genes in Enterobacterales spread via plasmids. Nosocomial outbreaks caused by Enterobacterales producing both CTX-M-2 and either IMP-1 or IMP-6-type carbapenemases have been reported. These organisms carry the incompatibility type N plasmid belonging to plasmid ST 5 (IncN-pST5). We investigated the construction process of the ESBL and carbapenemase genes co-carrying IncN-pST5. Methods: We retrospectively performed draft WGS analysis for blaIMP- or blaCTX-M-positive Enterobacterales in our strain collection (n = 281). Results: We selected four types of Escherichia coli plasmids for our study: type A, which carries both blaCTX-M-2 and blaIMP-1 (n = 6); type B, which carries both blaCTX-M-2 and blaIMP-6 (n = 2); type C, which carries blaCTX-M-2 (n = 10); and type D, which carries no ß-lactamase genes (n = 1). It should be noted that type D plasmid was only detected in E. coli TUM2805, which carries the blaCTX-M-14 on the IncB/O/B/Z plasmid. Long-read sequencing using MinION revealed that all types of IncN-pST5 were highly conserved and carried a class 1 integron. Integron numbers were type A for In798, type B for In1690, type C for In127 and type D for In207. Because the gene cassettes downstream of blaIMP were different between In798 and In1690, the change from blaIMP-1 to blaIMP-6 by point mutation was unlikely. Representative plasmids from types A, B and C were conjugatively transferred with quite a high frequency between 1.3 × 10-1 and 2.5 × 10-2. Conclusions: This study suggested that IncN-pST5 acquired blaCTX-M-2 by ISEcp1 in a stepwise manner, followed by either blaIMP-1 or blaIMP-6 into a class 1 integron.

High prevalence of colistin heteroresistance in specific species and lineages of Enterobacter cloacae complex derived from human clinical specimens.

BACKGROUND: Colistin (CST) is a last-line drug for multidrug-resistant Gram-negative bacterial infections. CST-heteroresistant Enterobacter cloacae complex (ECC) has been isolated. However, integrated analysis of epidemiology and resistance mechanisms based on the complete ECC species identification has not been performed. METHODS: Clinical isolates identified as "E. cloacae complex" by MALDI-TOF MS Biotyper Compass in a university hospital in Japan were analyzed. Minimum inhibitory concentrations of CST were determined by the broth microdilution method. The population analysis profiling (PAP) was performed for detecting the heteroresistant phenotype. The heat shock protein 60 (hsp60) cluster was determined from its partial nucleotide sequence. From the data of whole-genome sequencing, average nucleotide identity (ANI) for determining ECC species, multilocus sequence type, core genome single-nucleotide-polymorphism-based phylogenetic analysis were performed. phoPQ-, eptA-, and arnT-deleted mutants were established to evaluate the mechanism underlying colistin heteroresistance. The arnT mRNA expression levels were determined by reverse transcription quantitative PCR. RESULTS: Thirty-eight CST-resistant isolates, all of which exhibited the heteroresistant phenotype by PAP, were found from 138 ECC clinical isolates (27.5%). The prevalence of CST-resistant isolates did not significantly differ among the origin of specimens (29.0%, 27.8%, and 20.2% for respiratory, urine, and blood specimens, respectively). hsp60 clusters, core genome phylogeny, and ANI revealed that the CST-heteroresistant isolates were found in all or most of Enterobacter roggenkampii (hsp60 cluster IV), Enterobacter kobei (cluster II), Enterobacter chuandaensis (clusters III and IX), and Enterobacter cloacae subspecies (clusters XI and XII). No heteroresistant isolates were found in Enterobacter hormaechei subspecies (clusters VIII, VI, and III) and Enterobacter ludwigii (cluster V). CST-induced mRNA upregulation of arnT, which encodes 4-amino-4-deoxy-L-arabinose transferase, was observed in the CST-heteroresistant isolates, and it is mediated by phoPQ pathway. Isolates possessing mcr-9 and mcr-10 (3.6% and 5.6% of total ECC isolates, respectively) exhibited similar CST susceptibility and PAP compared with mcr-negative isolates. CONCLUSIONS: Significant prevalence (approximately 28%) of CST heteroresistance is observed in ECC clinical isolates, and they are accumulated in specific species and lineages. Heteroresistance is occurred by upregulation of arnT mRNA induced by CST. Acquisition of mcr genes contributes less to CST resistance in ECC.

Complete Genome Sequence of Polynucleobacter sp. Strain TUM22923, Isolated from Antarctic Lake Sediment.

Here, we report the complete genome sequence of Polynucleobacter sp. strain TUM22923, isolated from Antarctic lake sediment. This strain has a genome of 1,860,127 bp, comprising 1,848 protein-coding sequences. These sequence data could contribute to the elucidation of genome streamlining and low-temperature adaptation in members of Polynucleobacter, a cosmopolitan group of ultramicrobacteria.

Whole-Genome Sequences of Three Psychrotolerant Mycolicibacterium sp. Strains Isolated from Antarctic Soil.

We report the whole-genome sequences of three psychrotolerant Mycolicibacterium strains, TUM20983, TUM20984, and TUM20985, isolated from Antarctic soils. Taxonomic analyses indicate that these strains are putative new species. These genome sequences may provide insight into the cold adaptation mechanisms of Mycolicibacterium spp. through future comparative genomic studies.

Whole-Genome Sequencing of the Novel Pseudomonas Strain TUM22785 Harboring blaPAM-1, Isolated from a Patient with Urinary Tract Infection in Japan.

Pseudomonas species are Gram-negative aerobic bacteria that cause opportunistic infections. Here, we report the whole-genome sequence of the Pseudomonas sp. strain TUM22785, isolated from an outpatient with a urinary tract infection at a medical institution in Japan. This strain harbors a metallo-ß-lactamase (MBL) blaPAM-1 gene.

Full-length whole-genome sequencing analysis of emerged meropenem-resistant mutants during long-term in vitro exposure to meropenem for borderline meropenem-susceptible carbapenemase-producing and non-carbapenemase-producing Enterobacterales.

OBJECTIVES: Molecular analysis of meropenem-resistant mechanisms in mutants emerging from long-term in vitro meropenem exposure to borderline meropenem-susceptible carbapenemase-producing Enterobacterales (CPE) and non-CPE. METHODS: Escherichia coli TUM13867 harbouring both blaIMP-6- and blaCTX-M-2-carrying IncN plasmid and Citrobacter koseri TUM13189 with blaCTX-M-2-carrying chromosome were used. Meropenem MIC was 1 mg/L against both strains. Each strain was cultured in the hollow-fibre infection model (HFIM) to approximately 1 × 106 colony formation unit (cfu)/mL, and meropenem 1 g q8h treatment was initiated. Then, changes in total and meropenem-resistant populations were observed for 124 h. Meropenem resistance mechanisms were analysed using full-length whole-genome sequencing (WGS), reverse-transcription quantitative PCR and digital PCR. RESULTS: Meropenem reduced TUM13867 and TUM13189 to approximately 5 and 2 log10 cfu/mL, respectively, at 2 h after initiation, but regrowth was observed at 24 h. The meropenem-resistant mutant emergence frequency at 120 and 124 h was 4.4 × 10-4 for TUM13867 and 7.6 × 10-1 for TUM13189. Meropenem MIC of the mutants derived from TUM13867 (TUM20902) and TUM13189 (TUM20903) increased 4- and 16-fold, respectively. TUM20902, which harboured pMTY20902_IncN plasmid with a 27 505-bp deletion that included blaCTX-M-2, and blaIMP-6 showed 4.21-fold higher levels of transcription than the parental strain. TUM20903 had a 49 316-bp deletion that included ompC and a replicative increase of blaCTX-M-2 to three copies. CONCLUSIONS: Molecular analysis including full-length WGS revealed that the resistance mechanisms of meropenem-resistant mutants that emerged during long-term in vitro meropenem exposure were increased blaIMP-6 transcripts in CPE and increased blaCTX-M-2 transcripts due to gene triplication and OmpC loss resulting from ompC deletion in non-CPE.

Performance evaluation of Novaplex SARS-CoV-2 variants assay kit series for SARS-CoV-2 detection using single nucleotide polymorphisms.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have received increasing attention globally because of their increased transmissibility and potential to escape immunity. Although whole-genome sequencing is the gold standard method for SARS-CoV-2 mutation detection and lineage determination, it is costly and time-consuming. However, SARS-CoV-2 variants can be identified based on select variant-specific single nucleotide polymorphisms (SNPs) in the spike protein-encoding gene (S). This study validated and compared the limit of detection (LOD) of L452R, N501Y, HV69/70 del and E484K as variant-specific SNPs of the S gene and RdRP as a SARS-CoV-2-specific gene, using the Novaplex SARS-CoV-2 variants assay kit series. For three SARS-CoV-2 lineages (B.1.617.2, B.1.1.7 and R.1), one strain per lineage was used. Variant-specific SNPs of the S gene were analysed using the Novaplex SARS-CoV-2 variants I assay and Novaplex SARS-CoV-2 variants II assay kits. Validation confirmed the LODs of the variant kits. The LOD for each target variant-specific SNP and RdRP was five RNA copies per reaction. The Novaplex SARS-CoV-2 variants assay kit series performs well and the LOD for SARS-CoV-2 detection and variant-specific SNP detection are consistent. The kits are suitable for use as routine laboratory tests for SARS-CoV-2 and variant-specific SNP detection in a single step, saving time and labour.

Development of a Fully Automated Desktop Analyzer and Ultrahigh Sensitivity Digital Immunoassay for SARS-CoV-2 Nucleocapsid Antigen Detection.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has had a significant impact on public health and the global economy. Several diagnostic tools are available for the detection of infectious diseases, with reverse transcription-polymerase chain reaction (RT-PCR) testing specifically recommended for viral RNA detection. However, this diagnostic method is costly, complex, and time-consuming. Although it does not have sufficient sensitivity, antigen detection by an immunoassay is an inexpensive and simpler alternative to RT-PCR. Here, we developed an ultrahigh sensitivity digital immunoassay (d-IA) for detecting SARS-CoV-2 nucleocapsid (N) protein as antigens using a fully automated desktop analyzer based on a digital enzyme-linked immunosorbent assay. METHODS: We developed a fully automated d-IA desktop analyzer and measured the viral N protein as an antigen in nasopharyngeal (NP) swabs from patients with coronavirus disease. We studied nasopharyngeal swabs of 159 and 88 patients who were RT-PCR-negative and RT-PCR-positive, respectively. RESULTS: The limit of detection of SARS-CoV-2 d-IA was 0.0043 pg/mL of N protein. The cutoff value was 0.029 pg/mL, with a negative RT-PCR distribution. The sensitivity of RT-PCR-positive specimens was estimated to be 94.3% (83/88). The assay time was 28 min. CONCLUSIONS: Our d-IA system, which includes a novel fully automated desktop analyzer, enabled detection of the SARS-CoV-2 N-protein with a comparable sensitivity to RT-PCR within 30 min. Thus, d-IA shows potential for SARS-CoV-2 detection across multiple diagnostic centers including small clinics, hospitals, airport quarantines, and clinical laboratories.

Pneumonia Caused by Community-Acquired Methicillin-Resistant Staphylococcus aureus Positive for Exfoliative Toxin A and Secondary to Allergic Bronchopulmonary Aspergillosis.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) causes severe pneumonia. Previous reports found that CA-MRSA producing the Panton-Valentine leukocidin (PVL) or toxic shock syndrome toxin-1 (TSST-1) triggered severe necrotizing pneumonia. However, other toxins and genetic factors responsible for CA-MRSA pneumonia are rarely analyzed in Japan. In this study, we performed whole-genome sequencing (WGS) to analyze the clinical features of CA-MRSA genetically. As a result, we identified a strain with a rare sequence-type of MRSA. Herein, we present a case of CA-MRSA pneumonia in a 64-year-old woman. Her condition improved rapidly with vancomycin therapy. Draft WGS led to identifying the genotype and virulence factors and showed that the strain was a rare sequence-type of MRSA with the following characteristics: staphylococcal cassette chromosome mec (SCCmec) type IV, sequence type 121, exfoliative toxin A-positive, and specific staphylococcal protein A type t5110. To the best of our knowledge, a strain with this profile has not been previously reported. Our findings provide new insights into CA-MRSA pneumonia and its genetic and clinical features. Therefore, we recommend accumulating genetic profiles of CA-MRSA pneumonia to identify genetic features and the clinical characteristics of the patients.

Molecular and biochemical characterization of novel PAM-like MBL variants, PAM-2 and PAM-3, from clinical isolates of Pseudomonas tohonis.

BACKGROUND: There is no comprehensive study on PAM-like MBLs. OBJECTIVES: Our aim was to characterize novel B3 MBL variants, PAM-2 and PAM-3, from Pseudomonas tohonis clinical isolates. METHODS: We evaluated the antimicrobial susceptibility and the MBL gene composition of three novel P. tohonis clinical isolates identified at a Japanese hospital, using the broth microdilution method and WGS, respectively. We characterized the PAM-2 and PAM-3 proteins using recombinant protein expression and biochemical evaluations. RESULTS: Low carbapenem MICs (meropenem MIC = 0.125-1 mg/L) were observed for all three P. tohonis isolates; however, the isolates produced MBLs. We identified blaPAM-2 and blaPAM-3 as potential genes, belonging to a novel subclass of B3 MBLs. Their genomic sequence was similar to that of blaPAM-1 from Pseudomonas alcaligenes. PAM-2 and PAM-3 comprised 287 amino acids and exhibited 90% amino acid identity with PAM-1, 73% identity with POM-1 from Pseudomonas otitidis and 61% identity with L1 from Stenotrophomonas maltophilia. Biochemical evaluations of recombinant PAM-2 and PAM-3 revealed similar kcat/Km ratios and demonstrated catalytic activity against all the tested ß-lactams, except for aztreonam. In addition, the kcat/Km ratio for imipenem was 40-fold lower than that for meropenem. CONCLUSIONS: P. tohonis harbours a species-specific PAM-family MBL gene. This enzyme has higher hydrolytic activity against meropenem compared with that against imipenem.

First isolation of ST398 methicillin-resistant Staphylococcus aureus carrying staphylococcal cassette chromosome mec type IVd from pig ears in Japan.

The emergence and increasing prevalence of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) are a global concern. To investigate the prevalence and characteristics of sequence type 398 (ST398) MRSA in pig ears, 102 pig's ears were collected from 102 animals shipped from 51 farms at an abattoir. Eight ST398 MRSA isolates were isolated from the ears of eight pigs shipped from seven farms. Of the eight ST398 isolates, seven had the staphylococcal cassette chromosome mec (SCCmec) type IVd and these were obtained from seven pigs shipped from six farms. Single nucleotide polymorphisms ranging from 13 to 26 were observed in the core-genome regions in the seven SCCmec type IVd isolates. We believe that this is the first report on the isolation of ST398 MRSA SCCmec type IVd in Japan.

Clinical Presentation of Legionella pneumophila Serogroup 1-Associated Pneumonia and Diffuse Alveolar Hemorrhage: A Case Report and Literature Review.

BACKGROUND We report a case of diffuse alveolar hemorrhage (DAH) caused by Legionella pneumophila serogroup (SG) 1 and review the existing literature to identify risk factors and determine the prognosis of patients with Legionella pneumonia-associated DAH. CASE REPORT A 44-year-old woman was admitted to our hospital following the presentation of dyspnea for a few days. Chest computed tomography (CT) findings revealed "crazy-paving" pattern in the right upper lobe implicating DAH and consolidation in the lower lobe. Analysis of the bronchoalveolar lavage (BAL) fluid revealed DAH, with further analyses identifying L. pneumophila SG 1 as the causative agent. The patient was successfully treated with levofloxacin and a red blood cell transfusion and discharged on the 32nd day of hospitalization. A literature review of 6 reported cases (including our case) of Legionella pneumonia-associated DAH revealed that the median age of patients with DAH was 59 years (range, 44-75 years), involving female patients in 4 cases (67%) and the use of immunosuppressive drugs in 2 cases (33%). Three cases were BAL Legionella polymerase chain reaction (PCR)-positive and 4 cases were diagnosed using a urinary Legionella antigen test (one case was simultaneously PCR-positive). These infections were caused by L. pneumophila SG 1 in three cases and SG 3 in one case. Mechanical ventilation was used in 5 cases (83%) and one patient had an unfavorable prognosis. Steroids for DAH were used in 5 cases (83%), and 2 cases responded to this treatment. CONCLUSIONS Our case highlights that clinicians should be aware of Legionella spp. as a cause of DAH in an immunocompetent host with "crazy-paving" pattern on chest CT, and perform a urinary antigen test and BAL PCR for diagnosis.

Molecular Characterization of blaNDM-Carrying IncX3 Plasmids: blaNDM-16b Likely Emerged from a Mutation of blaNDM-5 on IncX3 Plasmid.

Dissemination of blaNDM, which is carried on the IncX3 plasmid, among Enterobacterales has been reported worldwide. In particular, blaNDM-5-carrying IncX3 plasmids can spread among several hosts, facilitating their dissemination. Other variants, such as blaNDM-17-, blaNDM-19-, blaNDM-20-, blaNDM-21-, and blaNDM-33-carrying IncX3 plasmids, have also been reported. Here, we characterized, using whole-genome sequencing (WGS), a blaNDM-16b-carrying IncX3 plasmid harbored by Escherichia coli strain TA8571, which was isolated from a urine specimen of a hospital inpatient in Tokyo, Japan. The blaNDM-16b differed in sequence from blaNDM-5 (C > T at site 698, resulting in an Ala233Val substitution). This blaNDM-16b-carrying IncX3 plasmid (pTMTA8571-1) is 46,161 bp in length and transferred via conjugation. Transconjugants showed high resistance to ß-lactam antimicrobials (except for aztreonam). Because pTMTA8571-1, which carries the Tn125-related region containing blaNDM and conjugative transfer genes, was similar to the previously reported IncX3 plasmids, we performed phylogenetic analysis based on the sequence of 34 shared genes in 142 blaNDM-carrying IncX3 plasmids (22,846/46,923 bp). Comparative analysis of the shared genes revealed short branches on the phylogenetic tree (average of 1.08 nucleotide substitutions per shared genes), but each blaNDM variant was divided into separate groups, and the structure of the tree correlated with the flowchart of blaNDM nucleotide substitutions. The blaNDM-carrying IncX3 plasmids may thereby have evolved from the same ancestral plasmid with subsequent mutation of the blaNDM. Therefore, pTMTA8571-1 likely emerged from a blaNDM-5-carrying IncX3 plasmid. This study suggested that the spread of blaNDM-carrying IncX3 plasmids may be a hotbed for the emergence of novel variants of blaNDM. IMPORTANCE blaNDM-carrying IncX3 plasmids have been reported worldwide. Harbored blaNDM variants were mainly blaNDM-5, but there were also rare variants like blaNDM-17, blaNDM-19, blaNDM-20, blaNDM-21, and blaNDM-33, including blaNDM-16b detected in this study. For these plasmids, previous reports analyzed whole genomes or parts of sequences among a small number of samples, whereas, in this study, we performed an analysis of 142 blaNDM-carrying IncX3 plasmids detected around the world. The results showed that regardless of the blaNDM variants, blaNDM-carrying IncX3 plasmids harbored highly similar shared genes. Because these plasmids already spread worldwide may be a hotbed for the emergence of rare or novel variants of blaNDM, increased attention should be paid to blaNDM-carrying IncX3 plasmids in the future.