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Escherichia coli ST131 is a multidrug-resistant lineage associated with the global spread of extended-spectrum ß-lactamase-producing organisms. Particularly, ST131 clade C1 is the most predominant clade in Japan, harboring blaCTX-M-14 at a high frequency. However, the process of resistance gene acquisition and spread remains unclear. Here, we performed whole-genome sequencing of 19 E. coli strains belonging to 12 STs and 12 fimH types collected between 1997 and 2016. Additionally, we analyzed the full-length genome sequences of 96 ST131-H30 clade C0 and C1 strains, including those obtained from this study and those registered in public databases, to understand how ST131 clade C1 acquired and spread blaCTX-M-14. We detected conjugative IncFII plasmids and IncB/O/K/Z plasmids carrying blaCTX-M-14 in diverse genetic lineages of E. coli strains from the 1990s to the 2010s, suggesting that these plasmids played an important role in the spread of blaCTX-M-14. Molecular phylogenetic and molecular clock analyses of the 96 ST131-H30 clade C0 and C1 strains identified 8 subclades. Strains harboring blaCTX-M-14 were clustered in subclades 4 and 5, and it was inferred that clade C1 acquired blaCTX-M-14 around 1993. All 34 strains belonging to subclade 5 possessed blaCTX-M-14 with ISEcp1 upstream at the same chromosomal position, indicating their common ancestor acquired blaCTX-M-14 in a single ISEcp1-mediated transposition event during the early formation of the subclade around 1999. Therefore, both the horizontal transfer of plasmids carrying blaCTX-M-14 to diverse genetic lineages and chromosomal integration in the predominant genetic lineage have contributed to the spread of blaCTX-M-14.
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OBJECTIVE: The aim of this study is to characterise the molecular characteristics of NDM-producing Enterobacterales, which have been on the increase in recent years in Japan, where IMP-producing bacteria are dominant among carbapenemase-producing Enterobacterales. METHODS: We collected 21 strains of NDM-producing Enterobacterales detected between 2015 and 2022 at five hospitals in Tokyo and performed illumina whole genome sequencing. For the seven selected strains, nanopore long-read sequencing was also performed to characterise the plasmids harbouring blaNDM. RESULTS: Fourteen strains were Escherichia coli and all carried blaNDM-5. Among these strains, eight and three were sequence type (ST) 410 and ST167, respectively, and both groups of strains were spread clonally in different hospitals. Two strains of Klebsiella pneumoniae ST147 carrying blaNDM-1 were detected in a hospital, and these strains had also spread clonally. The remainder included Enterobacter hormaechei, Klebsiella quasipneumoniae, Citrobacter amalonaticus, and Klebsiella michiganensis. Plasmid analysis revealed that an identical IncX3 plasmid harbouring blaNDM-5 was shared among four strains of different bacterial species (E. coli, C. amalonaticus, K. michiganensis, and E. hormaechei) detected at the same hospital. In addition, a Klebsiella quasipneumoniae strain detected at a different hospital also carried an IncX3 plasmid with a similar genetic structure. CONCLUSIONS: Nosocomial spread of multiple multidrug-resistant global clones and transmission of IncX3 plasmids harbouring blaNDM-5 among multiple species were detected as the major pathways of spread of NDM-producing Enterobacterales in Tokyo. Early detection of carriers and measures to prevent nosocomial spread are important to prevent further spread of NDM-producing organisms.
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Imipenemase (IMP) metallo-ß-lactamases (MBLs) hydrolyze almost all available ß-lactams including carbapenems and are not inhibited by any commercially available ß-lactamase inhibitor. Tebipenem (TP) pivoxil is the first orally available carbapenem and possesses a unique bicyclic azetidine thiazole moiety located at the R2 position. TP has potent in vitro activity against Enterobacterales producing extended-spectrum and/or AmpC ß-lactamases. Thus far, the activity of TP against IMP-producing strains is understudied. To address this knowledge gap, we explored the structure activity relationships of IMP MBLs by investigating whether IMP-6, IMP-10, IMP-25, and IMP-78 [MBLs with expanded hydrolytic activity against meropenem (MEM)] would demonstrate enhanced activity against TP. Most of the Escherichia coli DH10B strains expressing IMP-1 variants displayed a ≥twofold MIC difference between TP and MEM, while those expressing VIM or NDM variants demonstrated comparable MICs. Catalytic efficiency (kcat/KM) values for the TP hydrolysis by IMP-1, IMP-6, IMP-10, IMP-25, and IMP-78 were significantly lower than those obtained for MEM. Molecular dynamic simulations reveal that V67F and S262G substitutions (found in IMP-78) reposition active site loop 3, ASL-3, to better accommodate the bicyclic azetidine thiazole side chain, allowing microbiological/catalytic activity to approach that of comparison MBLs used in this study. These findings suggest that modifying the R2 side chain of carbapenems can significantly impact hydrolytic stability. Furthermore, changes in conformational dynamics due to single amino acid substitutions should be used to inform drug design of novel carbapenems.
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Antibacterianos , Azetidinas , Carbapenémicos , Dominio Catalítico , Escherichia coli , Pruebas de Sensibilidad Microbiana , Tiazoles , beta-Lactamasas , beta-Lactamasas/genética , beta-Lactamasas/metabolismo , Carbapenémicos/farmacología , Antibacterianos/farmacología , Tiazoles/farmacología , Tiazoles/química , Azetidinas/farmacología , Azetidinas/química , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Simulación de Dinámica Molecular , Meropenem/farmacología , Meropenem/química , Relación Estructura-ActividadRESUMEN
Purpose: The severe pathogenic ancient-type COVID-19, SARS-CoV-2/WA-1/2020 was the predominant gene variant in early 2020 in Japan, however, its transmissibility was uncertain. The period before the public commenced using any personal protective equipment (PPE) was evaluating to describe the transmissibility of the SARS-CoV-2/WA-1/2020. We analyzed the secondary attack rate (SAR) among close contacts and the risk factor for SAR. Methods: This retrospective cohort study included a total of 539 patients who were anticipated for the SARS-CoV-2/WA-1/2020 infection at Toho University Medical Center Omori Hospital from February to May 2020. We selected 54 patients with 1) exclude other pathogens infection, 2) include "Three Cs" condition: crowded places between distance< 6 feet, closed spaces indoor and close contact settings involving contact >15min with a person tested positive for SARS-CoV-2/WA-1/2020 without PPE. We evaluated alternative infection risks: the body mass index (BMI) and diabetes (DM) status (non-DM, pre-DM, and DM) as demographic determinants of transmissibility and infectivity of SARS-CoV2/WA-1/2020 cases during the incubation period. Results: The calculated SAR was 79.3%. BMI was significantly associated with the PCR positivity rate, which was significant in the univariate (CI 95%, 1.02-1.51; P = 0.03) and multivariate (CI 95%, 1.02-1.60; P = 0.03) analyses. Comparing the different BMI groups, the highest BMI group (25.5-35.8 kg/m2) had an elevated risk of SAR compared to the lowest BMI group (14.0-22.8 kg/m2), with an odds ratio of 1.41 (95% CI, 1.02-1.59; P = 0.03). There were no significant differences in the risk of SAR among different DM statuses. Conclusion: The transmissibility of SARS-CoV2/WA-1/2020 was high (79.3%) among household members without PPE who had "Three Cs" exposure. Although pre-DM and established DM did not confer a risk for transmissibility, higher BMI was associated with an increased risk of SAR. Trial Registration: UMIN Clinical Trials Registry, UMIN0000 50905.
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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.
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Proteínas Bacterianas , Infección Hospitalaria , Brotes de Enfermedades , Plásmidos , beta-Lactamasas , Humanos , Masculino , Lactante , Plásmidos/genética , beta-Lactamasas/genética , beta-Lactamasas/metabolismo , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Infección Hospitalaria/transmisión , Proteínas Bacterianas/genética , Infecciones por Enterobacteriaceae/epidemiología , Infecciones por Enterobacteriaceae/microbiología , Infecciones por Enterobacteriaceae/transmisión , Secuenciación Completa del Genoma , Niño , Preescolar , Femenino , Klebsiella/genética , Klebsiella/aislamiento & purificación , Klebsiella/efectos de los fármacos , Control de Infecciones/métodos , Enterobacteriaceae Resistentes a los Carbapenémicos/genética , Enterobacteriaceae Resistentes a los Carbapenémicos/aislamiento & purificaciónRESUMEN
The Japanese guidelines for the management of Clostridioides difficile infection (CDI) recommend metronidazole (MNZ) for non-severe cases and vancomycin (VCM) for severe cases. Here, we investigated the use of CDI antimicrobials and evaluated their clinical efficacy in four severity classifications and the validity of these classifications. A retrospective chart review was conducted on 137 inpatients with an initial positive C. difficile toxin test and initiation of CDI antimicrobials between April 2015 and March 2019. For the clinical efficacy analysis of the CDI antimicrobials and validation of the severity classifications, patients treated with VCM or oral MNZ were included. The endpoints were CDI recurrence rate, 30-day mortality rate, and diarrhea cure rate. No significant differences were found between the VCM and oral MNZ groups regarding the CDI recurrence rate (10.4% vs. 12.7%, p = 0.707), 30-day mortality rate (12.5% vs. 5.6%, p = 0.162), and diarrhea cure rate (61.9% vs. 72.7%, p = 0.238), regardless of the severity. Treatment with oral MNZ for non-severe cases was promising, confirming the usefulness of treatment according to Japanese guidelines. Further investigation of the clinical efficacy of oral MNZ in patients with first-episode CDI and evaluation of the preferable severity classification are warranted.
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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 (nâ=â17) 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 (MICâ≥â8â mg/L) with two or more amino-acid substitutions in quinolone-resistance-determining regions. Seven strains belonging to ST7363 (nâ=â3), ST1596 (nâ=â3) and ST1901 (nâ=â1) 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.
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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.
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Infección Hospitalaria , Staphylococcus aureus Resistente a Meticilina , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , Infecciones Estafilocócicas , Secuenciación Completa del Genoma , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Polimorfismo de Nucleótido Simple/genética , Humanos , Infección Hospitalaria/transmisión , Infección Hospitalaria/microbiología , Infecciones Estafilocócicas/transmisión , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/epidemiología , Secuenciación Completa del Genoma/métodos , Reacción en Cadena de la Polimerasa/métodos , Sistemas de Lectura Abierta/genética , Filogenia , Japón , Genoma Bacteriano/genéticaRESUMEN
BACKGROUND: The stigma perceived by many post-stroke persons hinders their social lives. A scale to measure stigma is needed to identify social problems related to stigma, and to evaluate effectiveness of interventions. OBJECTIVES: This study aimed to develop a Japanese version of the Stroke Stigma Scale (SSS-J), and confirm its utility by examining reliability and validity. METHODS: Eighty community-dwelling post-stroke individuals were enrolled at six sites. After translating the scale into Japanese using back translation methods, psychometric properties of the rating scale, internal scale validity, and reliability were examined to fit the Rasch model. Criterion-related validity, construct validity, and test-retest reliability were examined using total scores transformed to logit. For test-retest reliability, 30 participants completed the SSS-J twice, one week apart. RESULTS: Rasch analysis showed that the SSS-J had the best fit with 15 items on a 3-category rating scale. Item difficulty logits were -2.01 to 2.21, person ability logits were -4.69 to 0.62 (mean, -1.41), person reliability coefficient was 0.71 (separation index, 1.58), and item reliability coefficient was 0.96 (separation index, 5.04). For criterion validity, Spearman's rank correlation coefficient with the Center for Epidemiologic Studies Depression Scale was 0.51 (p < 0.001). For construct validity, Spearman's rank correlation coefficients with each subscale of the Stroke Impact Scale ranged from -0.36 to -0.16 (p = 0.002-0.126). For test-retest reliability, the intra-class correlation coefficient was 0.64 (p < 0.001). CONCLUSIONS: The SSS-J adapted to the Rasch model was reliable and valid. This scale can be used to quantitatively measure stigma among community-dwelling post-stroke persons in Japan.
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INTRODUCTION: Nucleic acid amplification tests (NAATs) play a pivotal role in clinical laboratories for diagnosing COVID-19. This study aimed to elucidate the accuracy of these tests. METHODS: In 2021, an external quality assessment of NAATs for SARS-CoV-2 was conducted in 47 laboratories in Tokyo, Japan. In open testing, where the laboratories knew that the samples were intended for the survey, a simulated nasopharyngeal swab suspension sample was used, featuring a positive sample A with a viral concentration of 50 copies/µL, positive sample B with 5 copies/µL, and a negative sample. Laboratories employing real-time RT-PCR were required to report cycle threshold (Ct) values. In blind testing, where the samples were processed as normal test samples, a positive sample C with 50 copies/µL was prepared using a simulated saliva sample. RESULTS: Of the 47 laboratories, 41 were engaged in open testing. For sample A, all 41 laboratories yielded positive results, whereas for sample B, 36 laboratories reported positive results, 3 laboratories reported "test decision pending", 1 laboratory reported "suspected positive", and 1 laboratory did not respond. All 41 laboratories correctly identified the negative samples as negative. The mean Ct values were 32.2 for sample A and 35.2 for sample B. In the blind test, six laboratories received samples. Sample C was identified as positive by five laboratories and negative by one laboratory. CONCLUSIONS: The nature of the specimen, specifically the saliva, may have influenced the blind test outcomes. The identified issues must be meticulously investigated and rectified to ensure accurate results.
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COVID-19 , Técnicas de Amplificación de Ácido Nucleico , SARS-CoV-2 , Humanos , SARS-CoV-2/genética , SARS-CoV-2/aislamiento & purificación , Tokio , COVID-19/diagnóstico , COVID-19/virología , Técnicas de Amplificación de Ácido Nucleico/métodos , Técnicas de Amplificación de Ácido Nucleico/normas , Prueba de Ácido Nucleico para COVID-19/métodos , Prueba de Ácido Nucleico para COVID-19/normas , Laboratorios Clínicos , Sensibilidad y Especificidad , Encuestas y CuestionariosRESUMEN
L1-like metallo-ß-lactamases (MBLs) exhibit diversity and are highly conserved. Although the presence of the blaL1-like gene is known, the biochemical characteristics are unclear. This study aimed to characterize an L1-like MBL from Stenotrophomonas lactitubi. It showed 70.9-99.7% similarity to 50 L1-like amino acid sequences. The characteristic kinetic parameter was its high hydrolyzing efficiency for ampicillin and nitrocefin. Furthermore, L1-like from S. lactitubi was distinctly more susceptible to inhibition by EDTA than that to inhibition by 2,6-pyridinedicarboxylic acid.
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Antibacterianos , beta-Lactamasas , Antibacterianos/farmacología , Antibacterianos/química , beta-Lactamasas/metabolismo , Stenotrophomonas/genética , Secuencia de AminoácidosRESUMEN
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.
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Toxinas Bacterianas , Enterotoxinas , Exotoxinas , Leucocidinas , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Superantígenos , Superantígenos/genética , Toxinas Bacterianas/genética , Exotoxinas/genética , Enterotoxinas/genética , Leucocidinas/genética , Humanos , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Infecciones Estafilocócicas/microbiología , Japón/epidemiología , Secuenciación Completa del Genoma , Duplicación de Gen , Masculino , Femenino , Persona de Mediana Edad , Anciano , Brotes de Enfermedades , Evolución Molecular , Adulto , Infecciones Comunitarias Adquiridas/microbiologíaRESUMEN
BACKGROUND: Mycobacterium avium is associated with pulmonary disease in otherwise healthy adults. Several clarithromycin-refractory cases have been reported, including some cases caused by clarithromycin-susceptible strains. OBJECTIVES: To characterize the reason for the discrepancy between clinical response and antibiotic susceptibility results. METHODS: We conducted population analysis of clarithromycin-tolerant and heteroresistant subpopulations of M. avium cultured in vitro and in homogenates of infected lungs of mice. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for 28 M. avium and two M. kansasii strains. Mice were intranasally infected with M. avium and treated with or without clarithromycin (100 mg/kg) thrice weekly. They were sacrificed on day 35 and the bacteria in lung homogenates were tested for clarithromycin resistance. Population analysis assays were performed based on colony growth on plates containing two-fold dilutions of clarithromycin. RESULTS: The MBC/MIC ratios were ≥8 in all 28 strains of M. avium tested. In the population analysis assay, several colonies were observed on the plates containing clarithromycin concentrations above the MIC (2-64 mg/L). No growth of M. kansasii colonies was observed on the plates containing clarithromycin concentrations ≥2 mg/L. M. avium in the homogenates of infected lungs showed clearer clarithromycin-resistant subpopulations than in vitro, regardless of clarithromycin exposure. CONCLUSION: M. avium shows intrinsic heterogeneous resistance (heteroresistance) to clarithromycin. This may explain the observed discrepancies between clarithromycin susceptibility testing results and clinical response to clarithromycin treatment. Further studies are needed to confirm a link between heteroresistance and clinical outcomes.
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Claritromicina , Farmacorresistencia Bacteriana , Pruebas de Sensibilidad Microbiana , Mycobacterium avium , Claritromicina/farmacología , Claritromicina/uso terapéutico , Animales , Ratones , Mycobacterium avium/efectos de los fármacos , Pulmón/microbiología , Femenino , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , HumanosRESUMEN
Taniborbactam (TAN; VNRX-5133) is a novel bicyclic boronic acid ß-lactamase inhibitor (BLI) being developed in combination with cefepime (FEP). TAN inhibits both serine and some metallo-ß-lactamases. Previously, the substitution R228L in VIM-24 was shown to increase activity against oxyimino-cephalosporins like FEP and ceftazidime (CAZ). We hypothesized that substitutions at K224, the homologous position in NDM-1, could impact FEP/TAN resistance. To evaluate this, a library of codon-optimized NDM K224X clones for minimum inhibitory concentration (MIC) measurements was constructed; steady-state kinetics and molecular docking simulations were next performed. Surprisingly, our investigation revealed that the addition of TAN restored FEP susceptibility only for NDM-1, as the MICs for the other 19 K224X variants remained comparable to those of FEP alone. Moreover, compared to NDM-1, all K224X variants displayed significantly lower MICs for imipenem, tebipenem, and cefiderocol (32-, 133-, and 33-fold lower, respectively). In contrast, susceptibility to CAZ was mostly unaffected. Kinetic assays with the K224I variant, the only variant with hydrolytic activity to FEP comparable to NDM-1, confirmed that the inhibitory capacity of TAN was modestly compromised (IC50 0.01 µM vs 0.14 µM for NDM-1). Lastly, structural modeling and docking simulations of TAN in NDM-1 and in the K224I variant revealed that the hydrogen bond between TAN's carboxylate with K224 is essential for the productive binding of TAN to the NDM-1 active site. In addition to the report of NDM-9 (E149K) as FEP/TAN resistant, this study demonstrates the fundamental role of single amino acid substitutions in the inhibition of NDM-1 by TAN.
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Antibacterianos , Ácidos Borínicos , Antibacterianos/farmacología , Simulación del Acoplamiento Molecular , Ácidos Carboxílicos/farmacología , Ácidos Borínicos/farmacología , Ceftazidima , Inhibidores de beta-Lactamasas/farmacología , beta-Lactamasas/metabolismo , Pruebas de Sensibilidad MicrobianaRESUMEN
BACKGROUND: Pseudomonas otitidis belongs to the genus Pseudomonas and causes various infections, including ear, skin, and soft tissue infections. P. otitidis has a unique susceptibility profile, being susceptible to penicillins and cephalosporins but resistant to carbapenems, due to the production of the metallo-ß-lactamase called POM-1. This revealed genetic similarities with Pseudomonas aeruginosa, which can sometimes lead to misidentification. CASE PRESENTATION: We report the case of a 70-year-old Japanese male who developed cellulitis and bacteremia during chemotherapy for multiple myeloma. He was initially treated with meropenem, but blood culture later revealed gram-negative bacilli identified as P. otitidis using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Carbapenem resistance was predicted from previous reports; therefore, we switched to dual therapy with levofloxacin and cefepime, and favorable treatment results were obtained. CONCLUSION: This is the first reported case of P. otitidis cellulitis and bacteremia in an immunocompromised patient. Carbapenems are typically used in immunocompromised patients and P. otitidis is often resistant to it. However, its biochemical properties are similar to those of Pseudomonas aeruginosa; therefore, its accurate identification is critical. In the present study, we rapidly identified P. otitidis using MALDI-TOF MS and switched from carbapenems to an appropriate antimicrobial therapy, resulting in a successful outcome.
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Bacteriemia , Infecciones por Pseudomonas , Humanos , Masculino , Anciano , Antibacterianos/uso terapéutico , Celulitis (Flemón)/diagnóstico , Celulitis (Flemón)/tratamiento farmacológico , Pseudomonas , Carbapenémicos/uso terapéutico , Infecciones por Pseudomonas/diagnóstico , Infecciones por Pseudomonas/tratamiento farmacológico , Pseudomonas aeruginosa , Bacteriemia/diagnóstico , Bacteriemia/tratamiento farmacológico , Huésped Inmunocomprometido , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodosRESUMEN
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 (nâ=â281). Results: We selected four types of Escherichia coli plasmids for our study: type A, which carries both blaCTX-M-2 and blaIMP-1 (nâ=â6); type B, which carries both blaCTX-M-2 and blaIMP-6 (nâ=â2); type C, which carries blaCTX-M-2 (nâ=â10); and type D, which carries no ß-lactamase genes (nâ=â1). 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 1.3â×â10-1 and 2.5â×â10-2. 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.
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L1 metallo-ß-lactamases produced by Stenotrophomonas maltophilia exhibit high diversity. Here, we characterized the genomes of Stenotrophomonas species harboring blaL1-like genes using publicly available genome sequences. Our findings provide evidence that Stenotrophomonas species with blaL1-like genes constitute a complex comprising many species with high genetic diversity, and similarities between blaL1-like genes are lower than those of the genome. This suggests that the diversity of blaL1-like is attributable to species diversity in Stenotrophomonas species harboring blaL1-like and the rapid evolutionary changes in blaL1-like genes.
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Stenotrophomonas maltophilia , Stenotrophomonas , Stenotrophomonas/genética , beta-Lactamasas/genética , Stenotrophomonas maltophilia/genéticaRESUMEN
We investigated the epidemiology and antimicrobial susceptibility profiles of seven major Gram-negative bacilli (Escherichia coli, Klebsiella spp., Enterobacter spp., Pseudomonas aeruginosa, Acinetobacter spp., Stenotrophomonas maltophilia, and Bacteroides spp.) that caused bacteremia in Japan. We collected clinical information and isolates from patients aged 20 years or older who developed bacteremia during a year at three Japanese university hospitals and performed microbiological examination. In total, 628 cases were included, half of which were caused by E. coli (315 isolates). P. aeruginosa (56 isolates) was isolated most frequently among non-fermenting bacteria and 33 Bacteroides spp. were isolated. Mortality rates were the highest for P. aeruginosa (7-day, 16.1%; 30-day, 26.8%). The 7- and 30-day mortality rates ranged 3.8-9.0% and 8.3-17.6%, respectively, for Enterobacterales, and they were 15.2% each for Bacteroides spp. Regarding antimicrobial resistance, Enterobacterales and Acinetobacter spp. showed susceptibility to carbapenems and amikacin (98.0-100.0%). The susceptibility rates to ceftolozane/tazobactam ranged 82.4-99.0% for Enterobacterales and 92.9% for P. aeruginosa. More than 30.0% of E. coli isolates were resistant to fluoroquinolone. Extended-spectrum ß-lactamase (ESBL) producers were found in 21.0% of E. coli and approximately 80% of those were resistant to fluoroquinolones. The susceptibility of the 33 Bacteroides spp. to carbapenems, ampicillin/sulbactam, and piperacillin/tazobactam was 100.0%. Among the ESBL producers, blaCTX-M group 9 was the major subgroup in E. coli (77.3%), and blaCTX-M group 1 was detected in 18.2% of E. coli and 50.0% of Klebsiella spp. Continuous surveillance is needed to understand the epidemiology and consider appropriate therapeutic strategies.
RESUMEN
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.