Development of a rapid detection method for the macrolide resistance gene in Mycobacterium avium using the amplification refractory mutation system-loop-mediated isothermal amplification method.

Macrolide antibiotics such as clarithromycin (CLR) and azithromycin are the key drugs used in multidrug therapy for Mycobacterium avium complex (MAC) diseases. For these antibacterial drugs, drug susceptibility has been correlated with clinical response in MAC diseases. We have previously demonstrated the correlation between drug susceptibility and mutations in the 23S rRNA gene, which confers resistance to macrolides. Herein, we developed a rapid detection method using the amplification refractory mutation system (ARMS)-loop-mediated isothermal amplification (LAMP) technique to identify mutations in the 23S rRNA gene of M. avium. We examined the applicability of the ARMS-LAMP method to genomic DNA extracted from six genotypes of M. avium clinical isolates. The M. avium isolates were classified into 21 CLR-resistant and 9 CLR-susceptible strains based on the results of drug susceptibility tests; the 23S rRNA genes of these strains were sequenced and analyzed using the ARMS-LAMP method. Sequence analysis revealed that the 9 CLR-sensitive strains were wild-type strains, whereas the 21 CLR-resistant strains comprised 20 mutant-type strains and one wild-type strain. Using ARMS-LAMP, no amplification from genomic DNAs of the 10 wild-type strains was observed using the mutant-type mismatch primer sets (MTPSs); however, amplification from the 20 mutant-type strain DNAs was observed using the MTPSs. The rapid detection method developed by us integrates ARMS-LAMP with a real-time turbidimeter, which can help determine drug resistance in a few hours. In conclusion, ARMS-LAMP might be a new clinically beneficial technology for rapid detection of mutations.IMPORTANCEMultidrug therapy for pulmonary Mycobacterium avium complex disease is centered on the macrolide antibiotics clarithromycin and azithromycin, and resistance to macrolides is an important prognosticator for clinical aggravation. Therefore, it is important to develop a quick and easy method for detecting resistance to macrolides. Drug resistance is known to be correlated with mutations in macrolide resistance genes. We developed a rapid detection method using amplification refractory mutation system (ARMS)-loop-mediated isothermal amplification (LAMP) to identify a mutation in the 23S rRNA gene, which is a macrolide resistance gene. Furthermore, we examined the applicability of this method using M. avium clinical isolates. The rapid method developed by us for detection of the macrolide resistance gene by integrating ARMS-LAMP and a real-time turbidimeter can help in detection of drug resistance within a few hours. Since this method does not require expensive equipment or special techniques and shows high analytical speed, it would be very useful in clinical practice.

A Rapid Screening Assay for Clarithromycin-Resistant Mycobacterium avium Complex Using Melting Curve Analysis with Nonfluorescent Labeled Probes.

Mycobacterium avium complex (MAC) thrives in various environments and mainly causes lung disease in humans. Because macrolide antibiotics such as clarithromycin or azithromycin are key drugs for MAC lung disease, the emergence of macrolide-resistant strains prevents the treatment of MAC. More than 95% of macrolide-resistant MAC strains are reported to have a point mutation in 23S rRNA domain V. This study successfully developed a melting curve assay using nonfluorescent labeled probes to detect the MAC mutation at positions 2058 to 2059 of the 23S rRNA gene (AA genotype, clarithromycin susceptible; TA, GA, AG, CA, AC, and AT genotypes, clarithromycin resistant). In the AA-specific probe assay, the melting peak of the DNA fragment of the AA genotype was higher than that of DNA fragments of other genotypes. Melting temperature (Tm) values of the AA genotype and the other genotypes were about 80°C and 77°C, respectively. DNA fragments of each genotype were identified correctly in six other genotype-specific probes (TA, GA, AG, CA, AC, and AT) assays. Using genomic DNA from six genotype strains of M. avium and four genotype strains of M. intracellulare, we confirmed that all genomic DNAs could be correctly identified as individual genotypes according to the highest Tm values among the same probe assays. These results indicate that this melting curve-based assay is able to determine MAC genotypes at positions 2058 to 2059 of the 23S rRNA gene. This simple method could contribute to the rapid detection of clarithromycin-resistant MAC strains and help to provide accurate drug therapy for MAC lung disease. IMPORTANCE Since macrolide antibiotics such as clarithromycin or azithromycin are key drugs in multidrug therapy for Mycobacterium avium complex (MAC) lung diseases, the rapid detection of macrolide-resistant MAC strains has important implications for the treatment of MAC. Previous studies have reported a correlation between drug susceptibility testing and the mutation of macrolide resistance genes. In this study, we developed a novel melting curve-based assay using nonfluorescent labeled probes to identify both clarithromycin-resistant M. avium and M. intracellulare with mutations in the 23S rRNA gene, which is the clarithromycin or azithromycin resistance gene. This assay contributed to not only the detection of MAC mutations but also the determination of all genotypes at positions 2058 to 2059 of the 23S rRNA gene. Furthermore, because nonfluorescent labeled probes are used, this assay is more easily and more immediately available than other methods.

Comparison between the effects of normal saline with and without heparin for the prevention and management of arterial catheter occlusion: a triple-blinded randomized trial.

PURPOSE: We aimed to compare the effects of saline with and without heparin on the catheter-occlusion rate and coagulation-related blood test results for the management of arterial catheters among patients admitted to a short-term intensive care unit postoperatively. METHODS: This prospective, triple-blinded, randomized controlled study recruited patients aged 20-90 years scheduled to undergo radial arterial catheter insertion and postoperative intensive care unit admission between February and August 2019. Patients were randomly allocated to two groups (1:1 ratio) depending on the use of heparin: study (normal saline with heparin, 3000 units to 500 ml of normal saline) and control (normal saline without heparin) groups with arterial catheters. The allocated management method was employed immediately after intensive care unit admission. Occlusion assessment (every 12 h), arterial blood gas tests (every 6 h), and blood sample collection (every 24 h) were performed. The occlusion of arterial catheter was assessed using occlusion rate, and blood test results were assessed using a linear mixed model. RESULTS: There were 147 patients in the arterial catheter groups. There were no significant differences in occlusion rates and changes in platelet counts and activated partial thromboplastin time between the groups with arterial (p = 0.98, 0.16, and 0.32, respectively) catheters during the first 6 days after intensive care unit admission. CONCLUSION: Normal saline with and without heparin showed similar efficiency for both the prevention of occlusion and the results of coagulation.

Prognostic Factors for Pediatric Acute Encephalopathy Associated with Severe Brain Edema.

BACKGROUND AND OBJECTIVE: Acute encephalopathy is a life-threatening brain dysfunction in children, often associated with a preceding infection and diffuse noninflammatory brain edema. At present, the role of decompressive craniectomy (DC) over the swollen area of the brain is unclear. The risk factors for predicting clinical deterioration also need clarification. METHODS: A retrospective study of pediatric patients admitted between 2015 and 2019 with acute cerebral encephalopathy was carried out. Patients were classified according to: (1) the preceding pathogens, (2) the syndromic classification, and (3) the extent of brain edema. The syndromic classification is a relatively new classification of acute encephalopathy proposed in 2016 and divides patients into 3 groups: those with systemic inflammatory reactions or "cytokine storms" (group 1), those with status epilepticus but no cytokine storm (group 2), and others (group 3). Glasgow Outcome Scale (GOS) scores of 1-3 were defined as unfavorable, while a GOS score of 4 or 5 was defined as a favorable outcome in this study. DC was performed for select patients with life-threatening signs of brainstem compression. RESULTS: Nineteen patients (mean age: 23.3 months) were included in the study, 8 (42.1%) of whom had an unfavorable outcome. There was no significant correlation between the types of pathogens and outcome. Unfavorable outcomes were observed in significantly more patients in group 1 (87.5%) than group 2 (14.3%) and group 3 (0%). There was a significant association between diffuse brain edema and unfavorable outcomes (72.7%). Neurosurgical DC was performed in 2 patients to alleviate life-threatening brainstem compression: one with a cytokine storm and diffuse bilateral brain edema, and the other with prolonged status epilepticus causing diffuse right-sided brain edema. The GOS score was 3 and 4, respectively. CONCLUSION: The risk factors for clinical deterioration in pediatric acute encephalopathy were evaluated based on a variety of classifications, including the new syndromic classification. Laboratory features of cytokine storms and radiological evidence of diffuse brain edema were associated with unfavorable outcomes. The role of surgical decompression is still controversial and should be assessed on a case-by-case basis.

Developmental changes in the occipital cranial sutures of children less than 2 years of age.

PURPOSE: The occipital bone is located on the boundary between the membranous and cartilage bones and contains a wide variety of accessory sutures. In this study, we describe the age distribution of pediatric patients who are less than 2 years of age with occipital cranial sutures using a three-dimensional computed tomography (3D-CT). METHODS: A total of 167 consecutive patients who are less than 2 years of age and underwent computed tomography for head trauma were included in this study. RESULTS: Based on the results of this study, various types of sutures were observed among the pediatric participants. In particular, superior median fissures, mendosal sutures, other interparietal segment's accessory sutures, and interparietal sutures were noted in 21%, 35%, 9%, and 6% of the participants, respectively. Additionally, Wormian bones within the lambdoid suture were noted in 32% of the patients. The median age of children with superior median fissure and mendosal suture was 0 month. Meanwhile, superior median fissure was not observed among children older than 5 months of age. In this population, 13 patients (8%) were found to have skull fracture. CONCLUSIONS: Knowledge of the normal cranial anatomy and developmental patterns of cranial sutures is crucial in the evaluation of questionable fractures in the occipital region. A combination of 3D-CT and axial bone window imaging is useful in differentiating normal structures from pathological changes in the cranium.

Quadrigeminal arachnoid cyst with perinatal encephalocele.

INTRODUCTION: Quadrigeminal arachnoid cyst (QAC) associated with encephalocele is rare; and while some treatments have been developed in recent years, no definite therapeutic approach for QAC has been established. Endoscopic treatment for arachnoid cyst is gaining popularity because it is relatively less invasive to the normal brain tissues. CASE PRESENTATION: The patient, a 4-year-old girl, presented with QAC associated with congenital occipital encephalocele. At the age of 1 month, repair of the perinatal encephalocele had been performed at another institute. An asymptomatic arachnoid cyst remained in the posterior fossa, which was closely monitored with follow up. At age 4 years, the patient started to complain of headache, which gradually increased in both strength and frequency. Magnetic resonance imaging (MRI) revealed cerebellar compression due to cyst enlargement. We performed neuroendoscopic cyst fenestration with an occipital bone approach. Post-operative MRI showed reduced size of the cyst, and the headache dramatically improved and resolved. DISCUSSION: The standard treatment of QAC is still controversial; however, our successful use of endoscopic fenestration toward the third ventricle indicates its efficacy and safety. QACs have been classified into 3 types based on their expansion mechanisms; our case might suggest another possible mechanism of QAC development. CONCLUSION: In our case, endoscopic cyst fenestration was successful for QAC with perinatal encephalocele. However, long-term follow-up and analysis of similar cases are needed to determine its effectiveness.

Tradescantia pallida extract inhibits biofilm formation in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is capable of biofilm formation. In this study, we investigated the effects of aqueous Tradescantia pallida extract on Pseudomonas aeruginosa growth and biofilm formation. Aqueous Tradescantia pallida extracts significantly inhibited both bacterial growth and biofilm formation. However, methanolic Tradescantia pallida extracts inhibited neither. Aqueous Tradescantia pallida extracts were deactivated by heating but were not deactivated by light exposure. The ingredients retained the inhibitory effect on the bacterial growth and biofilm formation after ultrafiltration of aqueous Tradescantia pallida extract. Furthermore, polyphenol-rich Tradescantia pallida extracts inhibited bacterial growth, thus, polyphenols are possible to be an active ingredient. We observed the biofilm by scanning electron microscopy, and quantitative and qualitative differences in the biofilm and cells morphology. Interestingly, the biofilm treated aqueous Tradescantia pallida extracts remained premature. We postulated that premature biofilm formation was due to the inhibition of swarming motility. Indeed, aqueous Tradescantia pallida extracts inhibited swarming motility. These results demonstrate that Peudomonas aeruginosa growth and biofilm formation are inhibited by aqueous Tradescantia pallida extracts.

The impact of probiotic Clostridium butyricum MIYAIRI 588 on murine gut metabolic alterations.

INTRODUCTION: Clostridium butyricum MIYAIRI 588 (CBM 588) is a probiotic bacterium used in antidiarrheal medicine in Japan. A few studies analyzed the changes in gut microbiome in patients treated with antimicrobials based on metagenomics sequencing. However, the impact of CBM 588 on gut metabolic alterations has not been fully elucidated. This study was to reveal the impact of CBM 588 on gut metabolic alterations. MATERIAL AND METHODS: In this in vivo study, mice were divided into four groups and CBM 588, clindamycin (CLDM), and normal saline (control) was orally administered (1. CLDM, 2. CBM 588, 3. CBM 588 + CLDM, 4. water) for 4 days. Fecal samples were collected to extract DNA for metagenomics analysis. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to obtain relative Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway abundance information derived from metagenomics data. RESULTS: CLDM treatment resulted in a dramatic increase in Firmicutes phylum compared to non-CLDM-treated groups (control and CBM 588-treated group). Then, the CBM 588 + CLDM-treated group showed a trend similar in many metabolic pathways to the CLDM-treated group. On the other hand, the CBM 588 + CLDM-treated group showed higher relative abundance compared to the CLDM-treated group especially in starch and sucrose metabolism. DISCUSSION: We concluded that CBM 588 caused a gut microbiome functional shift toward increased carbohydrate metabolism. These results support the hypothesis that CBM 588 treatment modulates gut microbiome under dysbiosis conditions due to antimicrobials.

Removal of a minimal amount of subdural hematoma is effective and sufficient for term neonates with severe symptomatic spontaneous parenchymal hemorrhage.

INTRODUCTION: Spontaneous parenchymal hemorrhage of term neonates is usually asymptomatic and does not require surgical intervention. However, there is no consensus on the management of cases with severe life-threatening symptoms, including repeated apnea, respiratory failure with severe cyanosis, severe bradycardia, or uncontrolled seizures. CASES: Our medical records of term neonates with intracranial hemorrhage who underwent surgical intervention were retrospectively reviewed. There were two cases with spontaneous parenchymal hemorrhage. Both cases were delivered vaginally without any use of forceps or vacuum devices. Neither of them showed asphyxia, hypoxic-ischemic encephalopathy, hematological abnormalities, congenital vascular anomalies, infection, or birth trauma. Common symptoms included apnea, cyanosis, bradycardia, and decreased consciousness. The original location of bleeding was the parenchyma of the right temporal lobe. The hemorrhage extended to subdural spaces in both cases. Subdural hematoma (SDH) removal was performed without manipulating the parenchymal hematoma. Only a small amount of SDH (approximately 5 ml) was drained spontaneously with irrigation, which was sufficient to decrease the elevated intracranial pressure. The patients' respiratory conditions improved dramatically after the surgery. CONCLUSION: We propose that removing only a small amount of SDH would be effective and sufficient to relieve severe symptoms of increased intracranial pressure in term neonates with massive spontaneous parenchymal hemorrhage.

Active surveillance in response to the identification of a single carbapenemase-producing Escherichia coli at a Japanese university hospital.

This report described the experience of active surveillance culture implemented in response to the identification of a single carbapenemase-producing Escherichia coli in a Japanese university hospital. It revealed a horizontal transmission event and an additional asymptomatic carrier of carbapenemase-producing Escherichia coli with unique drug susceptibility and resistance gene profiles. Early implementation of active surveillance culture as a part of multifaceted infection control measures appeared to be useful to control further transmission of carbapenemase-producing Escherichia coli even in the low endemic facility. Further investigations on the timing and usefulness of active surveillance culture in the control of carbapenemase-producing Enterobacteriaceae would be warranted.

Review of Past Reports and Current Concepts of Surgical Management for Craniosynostosis.

The purposes of surgery for craniosynostosis are to release increased intracranial pressure and to normalize cranial shape. The procedure was developed from a simple strip craniectomy in practice which ranged from the removal of the fused suture before the 1960s to total calvarial remodeling after 1970s and later methods of the 1990s, such as distraction and its modifications. According to its history, craniofacial surgeons might be changing their procedures with more effective, than less invasive ways. Since the late 1990s, when the distraction was applied to the craniofacial surgery, the gradual expansion, in particular of the anterior cranium, common in Japan, has long been controversial until the Caucasians accepted its use for the posterior cranium. Currently, the method may revert to the old procedure because a more sophisticated and better morphological result can be obtained depending on the types of deformity, even if a little more invasive maneuver is required. In other words, if treatment can be performed in optimal time, the procedures that were developed in the last half a century should be altered to each condition.

Molecular typing and genetic characterization of Mycobacterium avium subsp. hominissuis isolates from humans and swine in Japan.

Mycobacterium avium subsp. hominissuis (MAH) causes disease in both humans and swine; however, the genetic variations in MAH isolates are unclear. The aim of this study was to elucidate the genetic variations in MAH isolates from humans and swine in Japan. We analysed the 16S-23S rDNA internal transcribed spacer (ITS) sequence and variable number of tandem repeats (VNTRs) using the Mycobacterium avium tandem repeat loci, prevalence of ISMav6 and clarithromycin resistance for MAH isolates from patients with pulmonary MAC (pMAC) disease (n=69), and HIV-seropositive and blood culture-positive (HIV-MAC) patients (n=28) and swine (n=23). In the minimum spanning tree based on VNTR analysis, swine MAC isolates belonged to a cluster distinguishable from that of human pMAC isolates. Isolates from HIV-MAC were scattered throughout both clusters. The three major distinct sequevars, Mav-A, Mav-B and Mav-F, were determined according to 16S-23S rDNA ITS sequence analysis in addition to three new sequevars, Mav-Q, Mav-R and Mav-S. Mav-A and Mav-F comprised the majority of human pMAC strains; in contrast, Mav-B predominated in swine isolates. Distribution of ITS sequevars in the minimum spanning tree based on VNTR analysis showed similar clusters of isolates from different origins, i.e. human pMAC, HIV-MAC and swine. These results, together with ISMav6 possession and clarithromycin resistance, revealed the genetic diversity of MAH strains recovered from humans and swine. Molecular epidemiology and genetic characterization in the present study showed the distinctive genetic evolutionary lineage of MAH strains isolated from human pMAC diseases and swine.

The first point prevalence survey of health care-associated infection and antimicrobial use in a Japanese university hospital: A pilot study.

BACKGROUND: Point prevalence surveys (PPSs) in Japanese hospitals have not yet been reported. The purpose of this pilot PPS study was to evaluate the epidemiology of health care-associated infections (HAIs) and antimicrobial use in a Japanese tertiary university hospital. METHODS: A 1-day, cross-sectional PPS was performed at a Japanese university hospital. Data on demographics, active HAIs, and antimicrobial use of all inpatients were collected using a data collection form. RESULTS: Of 841 patients, 85 (10.1%) had 90 active HAIs, and 308 patients (36.6%) were administered 494 antimicrobials. Among the 90 HAIs and 58 pathogens, the most frequent infection and isolated pathogen were pneumonia (20.0%) and Enterobacteriaceae (27.6%), respectively. Of the 118 antimicrobials used for treatment of HAIs, carbapenems were the most frequently administered category of antimicrobials (22.9%). In regard to antimicrobials for surgical prophylaxis, 37 of 119 (31.1%) were administered to patients on postoperative day 3 or later, and 48 of 119 (40.3%) were administered orally. CONCLUSIONS: The incidence of HAIs is higher than in other developed countries. The social and medical situation in Japan may affect patient demographics, active HAIs, and antimicrobial use. Multicenter PPSs are necessary to uncover the real epidemiology of HAIs and antimicrobial use in Japan.

Genetic diversity of clinical Mycobacterium avium subsp. hominissuis and Mycobacterium intracellulare isolates causing pulmonary diseases recovered from different geographical regions.

Mycobacterium avium complex (MAC) infections are increasing annually in many countries. MAC strains are the most common nontuberculous mycobacterial pathogens isolated from respiratory samples and predominantly consist of two species, Mycobacterium avium and Mycobacterium intracellulare. The aim of this study was to analyze the molecular epidemiology and genetic backgrounds of clinical MAC isolates collected from The Netherlands, Germany, United States, Korea and Japan. Variable numbers of tandem repeats (VNTR) analysis was used to examine the genetic relatedness of clinical isolates of M. avium subsp. hominissuis (n=261) and M. intracellulare (n=116). Minimum spanning tree and unweighted pair group method using arithmetic averages analyses based on the VNTR data indicated that M. avium subsp. hominissuis isolates from Japan shared a high degree of genetic relatedness with Korean isolates, but not with isolates from Europe or the United States, whereas M. intracellulare isolates did not show any specific clustering by geographic origin. The findings from the present study indicate that strains of M. avium subsp. hominissuis, but not M. intracellulare, exhibit geographical differences in genetic diversity and imply that MAC strains may have different sources, routes of transmission and perhaps clinical manifestations.

Characterization of a novel plasmid, pMAH135, from Mycobacterium avium subsp. hominissuis.

Mycobacterium avium complex (MAC) causes mainly two types of disease. The first is disseminated disease in immunocompromised hosts, such as individuals infected by human immunodeficiency virus (HIV). The second is pulmonary disease in individuals without systemic immunosuppression, and the incidence of this type is increasing worldwide. M. avium subsp. hominissuis, a component of MAC, causes infection in pigs as well as in humans. Many aspects of the different modes of M. avium infection and its host specificity remain unclear. Here, we report the characteristics and complete sequence of a novel plasmid, designated pMAH135, derived from M. avium strain TH135 in an HIV-negative patient with pulmonary MAC disease. The pMAH135 plasmid consists of 194,711 nucleotides with an average G + C content of 66.5% and encodes 164 coding sequences (CDSs). This plasmid was unique in terms of its homology to other mycobacterial plasmids. Interestingly, it contains CDSs with sequence homology to mycobactin biosynthesis proteins and type VII secretion system-related proteins, which are involved in the pathogenicity of mycobacteria. It also contains putative conserved domains of the multidrug efflux transporter. Screening of isolates from humans and pigs for genes located on pMAH135 revealed that the detection rate of these genes was higher in clinical isolates from pulmonary MAC disease patients than in those from HIV-positive patients, whereas the genes were almost entirely absent in isolates from pigs. Moreover, variable number tandem repeats typing analysis showed that isolates carrying pMAH135 genes are grouped in a specific cluster. Collectively, the pMAH135 plasmid contains genes associated with M. avium's pathogenicity and resistance to antimicrobial agents. The results of this study suggest that pMAH135 influence not only the pathological manifestations of MAC disease, but also the host specificity of MAC infection.

Comparative genome analysis of Mycobacterium avium revealed genetic diversity in strains that cause pulmonary and disseminated disease.

Mycobacterium avium complex (MAC) infection causes disseminated disease in immunocompromised hosts, such as human immunodeficiency virus (HIV)-positive patients, and pulmonary disease in persons without systemic immunosuppression, which has been increasing in many countries. In Japan, the incidence of pulmonary MAC disease caused by M. avium is about 7 times higher than that caused by M. intracellulare. To explore the bacterial factors that affect the pathological state of MAC disease caused by M. avium, we determined the complete genome sequence of the previously unreported M. avium subsp. hominissuis strain TH135 isolated from a HIV-negative patient with pulmonary MAC disease and compared it with the known genomic sequence of M. avium strain 104 derived from an acquired immunodeficiency syndrome patient with MAC disease. The genome of strain TH135 consists of a 4,951,217-bp circular chromosome with 4,636 coding sequences. Comparative analysis revealed that 4,012 genes are shared between the two strains, and strains TH135 and 104 have 624 and 1,108 unique genes, respectively. Many strain-specific regions including virulence-associated genes were found in genomes of both strains, and except for some regions, the G+C content in the specific regions was low compared with the mean G+C content of the corresponding chromosome. Screening of clinical isolates for genes located in the strain-specific regions revealed that the detection rates of strain TH135-specific genes were relatively high in specimens isolated from pulmonary MAC disease patients, while, those of strain 104-specific genes were relatively high in those from HIV-positive patients. Collectively, M. avium strains that cause pulmonary and disseminated disease possess genetically distinct features, and it suggests that the acquisition of specific genes during strain evolution has played an important role in the pathological manifestations of MAC disease.

[Extensive genetic analysis of clinical tuberculosis isolates and analysis of host factors to evaluate rapid development of multidrug resistance during initial treatment].

INTRODUCTION: In this study, we aimed at determining the cause of resistance to tuberculosis treatment by performing genetic analyses of bacteria obtained from a patient who developed multidrug-resistant tuberculosis (MDR-TB) during the initial course of treatment for tuberculosis. METHODS: Specimens obtained before and after the development of MDR-TB were subjected to spoligotyping, drug-resistance gene analysis, and variable-number tandem repeat (VNTR) typing. The patient's clinical background was also reviewed. RESULTS: After the development of resistance, the bacterial genome had changed with regard to only 1 mutation: S531L in the rpoB gene. Spoligotyping revealed that the genotype was that of the Beijing strain. VNTR typing confirmed all 35 loci. Review of the patient's clinical background showed that diabetes mellitus was present as a complication. DISCUSSION: There was no evidence of reinfection or polyclonal infection. The strain belonged to a sublineage of the Beijing genotype that is a common precipitating cause of MDR-TB due to this genotype. The patient had diabetes mellitus and was thus vulnerable to the development of resistance. Factors associated with both the host and bacteria, therefore, contributed to the development of resistance in this case, which seemed to result in the rapid development of MDR-TB.

[Identification of novel variable number tandem repeat (VNTR) loci in Mycobacterium avium and development of an effective means of VNTR typing].

INTRODUCTION: To make more effective use of variable number tandem repeat (VNTR) typing, we identified novel VNTR loci in Mycobacterium avium and used them for modified M. avium tandem repeat-VNTR (MATR-VNTR) typing. METHOD: Analysis of a DNA sample extracted from a clinical isolate (strain HN135) with the FLX system genome sequencer (Roche Diagnostic System) led to discovery of several novel VNTR loci. The allelic diversity of the novel VNTR loci was evaluated for 71 clinical isolates and compared with the diversity of the MATR-VNTR loci. To improve efficacy of MATR-VNTR typing, we tested typing using 2 sets of loci selected from the newly identified loci and the MATR loci, i.e., one set containing 7 and another 16 loci. Hunter Gaston's discriminatory index (HGDI) was calculated for these sets. RESULTS: Six VNTR loci were newly identified, of which 5 showed a high diversity. The HGDI was 0.980 for the improved new typing using a set of 7 loci, and 0.995 for another set of 16 loci, while it was 0.992 for the conventional MATR-VNTR typing. DISCUSSION: VNTR typing with the set of the 7 loci enabled a rapid analysis, and another set of 16 loci enabled a precise analysis, as compared with conventional MATR-VNTR typing. A method that uses only VNTR loci with relatively high allelic diversity is considered to be a useful tool for VNTR typing of MAC isolates.

Bismuth protects against arsenite-induced inhibition of proteoglycan synthesis in cultured vascular endothelial cells.

Chronic ingestion of arsenic is associated with an increased risk of vascular disease such as atherosclerosis. Previously, we showed that arsenite inhibits the synthesis of general proteoglycans (PGs), which are key molecules in the progression of atherosclerosis, in vascular endothelial cells. In the present study, we investigated the effect of several metals on arsenite-induced inhibitory effect in endothelial cells. The results indicate that, after 24-hr incubation, the inhibition of PG synthesis caused by sodium arsenite was protected by bismuth nitrate but not zinc sulfate, manganese chloride, nickel chloride or cobalt chloride. The accumulation of arsenic in the cell layer was significantly decreased by bismuth after 12-hr incubation and that of bismuth was also decreased by arsenite. It was therefore suggested that the protective effect of bismuth against the inhibitory effect of arsenite on PG synthesis in vascular endothelial cells may be due, at least in part, to the decrease in cellular arsenic accumulation.

[A study of genetic characteristics of Mycobacterium avium strains from patients with pulmonary M. avium disease in Japan and Korea].

INTRODUCTION: To determine the characteristics of Mycobacterium avium in Japan, we compared the genetic properties of M. avium isolated in different countries. METHODS: A Mycobacterium avium tandem-repeat variable-number tandem-repeat (MATR-VNTR) analysis was performed using South Korean strains (n = 119) and Japanese strains (n = 76). In addition, we compared the frequencies of a new insertion sequence, ISMav6. RESULTS: A phylogenetic analysis identified different clusters between the two countries' strains. The prevalence of ISMav6 was significantly different between them, i.e., 75.0% in Japanese strains and 59.8% in the Korean ones (P < 0.035). The frequency of strains with IS Mav6 in the Shine-Dalgarno (SD) sequence of the cfp29 gene that is involved in the interferon-gamma induction was also different, with stronger significance (Japan: 38.2%, Korea: 12.4%, P < 0.001). DISCUSSION: It is possible that M. avium strains prevalent in Japan and in Korea are genetically distinct. The analyses of the presence of ISMav6, as well as the VNTR patterns of M.avium strains from many different countries would be a promising methodology in elucidating the causes of the recent increase in cases of pulmonary MAC diseases.