Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam.

Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.

Common isolation of New Delhi metallo-beta-lactamase 1-producing Enterobacteriaceae in a large surgical hospital in Vietnam.

This study sought to monitor the presence of carbapenem-resistant Enterobacteriaceae (CRE) and the proportion New Delhi metallo-beta-lactamase 1 (NDM-1)-producing bacteria between August 2010 and December 2012 in a surgical hospital in Vietnam. We identified 47 CRE strains from a total of 4,096 Enterobacteriaceae isolates (1.1 %) that were NDM-1-positive from 45 patients admitted to 11 different departments, with the majority being from the urology department. The NDM-1 gene was found in seven different species. Genotyping revealed limited clonality of NDM-1-positive isolates. Most of the isolates carried the NDM-1 gene on a plasmid and 17.8 % (8/45) of those were readily transferable. We found five patients at admission and one patient at discharge with NDM-1-positive bacteria in their stool. From 200 screening environmental hospital samples, five were confirmed to be NDM-1-positive and included Acinetobacter species (n = 3) and Enterobacter aerogenes (n = 2). The results reveal that NDM-1-producing Enterobacteriaceae are commonly isolated in patients admitted to a Vietnamese surgical hospital and are also detected in the hospital environment.

Surveillance of multi-drug resistance phenotypes in Staphylococcus aureus in Japan and correlation with whole-genome sequence findings.

BACKGROUND: Antimicrobial resistance in Staphylococcus aureus imposes a high disease burden. Both phenotypic and genotypic monitoring are key to understanding and containing emerging resistant strains. AIM: Phenotypic monitoring of emerging resistance in S. aureus and correlation of priority strain phenotypes with whole-genome sequencing (WGS) findings. METHODS: Antimicrobial susceptibility test results of >40,000 isolates from 213 participating hospitals from 2011 to 2019 were exported from the national Japan Nosocomial Infections Surveillance (JANIS) database. Longitudinal and geographic distribution and prevalence of distinct multi-drug resistance phenotypes ('resistance profiles') of S. aureus were examined among hospitals and prefectures. We further conducted a genome sequence analysis of strains with specific resistance profiles of concern. FINDINGS: The overall prevalence of meticillin-resistant S. aureus (MRSA) decreased from 40.3% to 35.1% from 2011 to 2019. However, among dozens of S. aureus resistance profiles, only one profile of a type of MRSA, exhibited a statistically significant increase in inpatient frequency, exceeding 10% during the nine years. This MRSA profile showed resistance to oxacillin, erythromycin and levofloxacin. Analysis of WGS results of S. aureus isolates with this phenotype revealed that most belonged to clonal complex 8, and all carried SCCmec IV, typical of community-acquired MRSA. CONCLUSION: Tracking distinct resistance profiles deepened our understanding of the overall decrease in MRSA and led to recognition of the emergence of a new resistance phenotype. This study provides a model for future epidemiological research on antimicrobial resistance correlating multi-drug resistance phenotypes with selective genome sequencing, which can be applied to other bacterial species.

Impact of the COVID-19 pandemic on the surveillance of antimicrobial resistance.

BACKGROUND: The impact of the coronavirus disease (COVID-19) pandemic on antimicrobial resistance (AMR) is a major concern. AIM: To compare the number of patients and isolation rate of antimicrobial-resistant bacteria before and after the beginning of the COVID-19 pandemic using the comprehensive national surveillance data. METHODS: We utilized comprehensive surveillance data, collected in the Japan Nosocomial Infections Surveillance programme, which included a total of 16.7 million samples of 5.9 million tested patients from >1300 hospitals. We compared the number of patients and isolation rate of five bacteria between 2019 and 2020, including antimicrobial-susceptible and -resistant bacteria of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. FINDINGS: The number of patients and isolation rate of S. aureus and meticillin-resistant S. aureus decreased slightly; those of S. pneumoniae and penicillin-resistant S. pneumoniae decreased by 60%; and those of third-generation cephalosporin-resistant K. pneumoniae increased. The isolation rate of the remaining bacteria apparently increased, although the number of patients decreased. This was due to a substantial decrease in the total number of tested patients (the denominator of the isolation rate), which was larger than that of the number of patients (the numerator of the isolation rate). Consistent results were obtained when the same data were re-aggregated using the procedure of the World Health Organization Global Antimicrobial Resistance Surveillance System, demonstrating the general importance of this problem. CONCLUSION: Surveillance data during the COVID-19 pandemic must be carefully interpreted based on examination of the numerator, denominator and background factors that affect the denominator.

Immunohistochemical localization of elastin, fibrillins and microfibril-associated glycoprotein-1 in the developing periodontal ligament of the rat molar.

BACKGROUND AND OBJECTIVE: Elastic system fibers are a major component of the periodontal ligament, but little information is available about their detailed composition or the mechanism of elastogenesis in the developing periodontal ligament. The purpose of this study was to investigate immunolocalization of elastin, fibrillins and microfibril-associated glycoprotein-1 (MAGP-1) in the developing periodontal ligament of the rat molar. MATERIAL AND METHODS: Frozen sections of demineralized as well as non-demineralized periodontal ligament of Wistar rats of various ages from 19 days to 7 weeks were incubated with anti-elastin, anti-fibrillin-1 and -2 and anti-MAGP-1 antibodies followed by peroxidase-conjugated secondary antibodies. After incubation with diaminobenzidine solution, immunoreaction products were observed with a light microscope. RESULTS: In the developing periodontal ligament of 19-day-old rats, fibers immunopositive to elastin were not present, but fibers positively stained for fibrillin-2 and MAGP-1 were widely distributed throughout the ligament. The latter fibers were arranged in the apico-occlusal direction along with blood vessels. In 3-week-old rats, fibers stained for elastin were observed for the first time in the apical region of the ligament. The number and distribution pattern of these elastin-positive fibers was basically the same as those in rats aged 5 and 7 weeks. In contrast, fibrillin-2- and MAGP-1-positive fibers were more extensively distributed in the ligament, and their pattern of distribution was comparable to that of reported oxytalan fibers. Fibrillin-1 was, however, not detected either in demineralized sections or in non-demineralized sections, indicating its absence in periodontal ligament. CONCLUSION: Elastin expressed in the periodontal ligament assembled into elaunin fibers in the vicinity of blood vessels. Both fibrillin-2 and MAGP-1 are structural components not only of the elastin-associated microfibrils but also of elastin-free microfibrils, with possible roles in elastogenesis and in periodontal ligament homeostasis.

Genes responsible for dextran-dependent aggregation of Streptococcus sobrinus strain 6715.

INTRODUCTION: Streptococcus sobrinus exhibits more significant dextran-dependent aggregation mediated by glucan-binding proteins than Streptococcus mutans. We have identified four glucan-binding protein C gene (gbpC) homologues designated as gbpC1, gbpC2, dblA and dblB in S. sobrinus in contrast to the single gene gbpC in S. mutans. We attempted to determine which gene is most responsible for the dextran-dependent aggregation of S. sobrinus. METHODS: We introduced mutation with a chemical mutagen, 1-methyl-3-nitro-1-nitrosoguanidine, into S. sobrinus strain 6715 and analysed the four gbpC homologous gene sequences in the parental strain 6715 and an obtained aggregation-negative mutant NUM-Ssg99. We also examined the localization of proteins encoded by these genes in the mutant NUM-Ssg99. RESULTS: The nucleotide sequences of the gbpC1, gbpC2 and dblA genes in NUM-Ssg99 were 100% identical to the homologous genes in parental strain 6715. In contrast, a truncated mutation was detected in the dblB gene and the mutant protein devoid of the LPXTG motif was confirmed by Western blot analysis to be released into the extracellular milieu. CONCLUSION: We conclude that the dblB gene among the four GbpC homologous protein genes is most responsible for aggregation in strain 6715.

Reduction in chlorhexidine efficacy against multi-drug-resistant Acinetobacter baumannii international clone II.

BACKGROUND: Nosocomial infections caused by Acinetobacter baumannii international clone II (IC II) can cause severe clinical outcomes. AIM: Differential evaluation of bactericidal efficacy of chlorhexidine gluconate (CHX) and benzethonium chloride (BZT) disinfectants against IC II and non-IC II isolates. METHODS: Minimum inhibitory concentrations (MICs) of CHX and BZT were determined for 137 A. baumannii IC II, 99 non-IC II and 69 non-baumannii isolates, further classified according to MIC values into disinfectant-reduced susceptible (DRS) and disinfectant-susceptible (DS) groups. Time-kill curves and minimum bactericidal concentrations (MBCs) were evaluated for representative isolates in each group. RESULTS: CHX and BZT MIC90s for IC II isolates were 100 and 175mg/L, respectively, but those for non-IC II and non-baumannii isolates were <100mg/L. Nevertheless, time-kill curves indicated that CHX and BZT reduced live bacterial cell number by 5 log10 for IC II and non-IC II isolates within 30s when used at 1000mg/L, comparable to practical use concentrations. CHX MBC at 30s was 1000mg/L for IC II and non-IC II isolates, and was not influenced by addition of 3% bovine serum albumin (BSA); BZT MBC at 30s was 100mg/L without BSA and increased up to 500mg/L upon addition of BSA. No significant differences in BSA were found between DRS and DS isolates. CONCLUSION: CHX and BZT were effective against Acinetobacter spp. including IC II at a concentration of 1000mg/L and exposure for at least 30s, but their concentrations should be considered carefully to ensure sufficient effects in both clinical and healthcare settings.

Laboratory-based surveillance of pertussis using multitarget real-time PCR in Japan: evidence for Bordetella pertussis infection in preteens and teens.

Between January 2013 and December 2014, we conducted laboratory-based surveillance of pertussis using multitarget real-time PCR, which discriminates among Bordetella pertussis, Bordetella parapertussis, Bordetella holmesii and Mycoplasma pneumoniae. Of 355 patients clinically diagnosed with pertussis in Japan, B. pertussis, B. parapertussis and M. pneumoniae were detected in 26% (n = 94), 1.1% (n = 4) and 0.6% (n = 2), respectively, whereas B. holmesii was not detected. It was confirmed that B. parapertussis and M. pneumoniae are also responsible for causing pertussis-like illness. The positive rates for B. pertussis ranged from 16% to 49%, depending on age. Infants aged ≤ 3 months had the highest rate (49%), and children aged 1 to 4 years had the lowest rate (16%, p < 0.01 vs. infants aged ≤ 3 months). Persons aged 10 to 14 and 15 to 19 years also showed high positive rates (29% each); the positive rates were not statistically significant compared with that of infants aged ≤ 3 months (p ≥ 0.06). Our observations indicate that similar to infants, preteens and teens are at high risk of B. pertussis infection.

Variation in patient position and impact on carbon-ion scanning beam distribution during prostate treatment.

OBJECTIVE: We assessed the impact of changes in patient position on carbon-ion scanning beam distribution during treatment for prostate cancer. METHODS: 68 patients were selected. Carbon-ion scanning dose was calculated. Two different planning target volumes (PTVs) were defined: PTV1 was the clinical target volume plus a set-up margin for the anterior/lateral sides and posterior side, while PTV2 was the same as PTV1 minus the posterior side. Total prescribed doses of 34.4 Gy [relative biological effectiveness (RBE)] and 17.2 Gy (RBE) were given to PTV1 and PTV2, respectively. To estimate the influence of geometric variations on dose distribution, the dose was recalculated on the rigidly shifted single planning CT based on two dimensional-three dimensional rigid registration of the orthogonal radiographs before and after treatment for the fraction of maximum positional changes. RESULTS: Intrafractional patient positional change values averaged over all patients throughout the treatment course were less than the target registration error = 2.00 mm and angular error = 1.27°. However, these maximum positional errors did not occur in all 12 treatment fractions. Even though large positional changes occurred during irradiation in all treatment fractions, lowest dose encompassing 95% of the target (D95)-PTV1 was >98% of the prescribed dose. CONCLUSION: Intrafractional patient positional changes occurred during treatment beam irradiation and degraded carbon-ion beam dose distribution. Our evaluation did not consider non-rigid deformations, however, dose distribution was still within clinically acceptable levels. ADVANCES IN KNOWLEDGE: Inter- and intrafractional changes did not affect carbon-ion beam prostate treatment accuracy.

Increased adherence of T cells to human endothelial cells in patients with human T-cell lymphotropic virus type I-associated myelopathy.

We investigated the adherence of T cells to human umbilical vein endothelial cells in seven patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy. The adherence of T cells to endothelial cells increased significantly in all the patients with HTLV-I-associated myelopathy when compared with the adherence in the seronegative controls (1.3- to 2.8-fold) and compared with the adherence in the anti-HTLV-I-seropositive non-HTLV-I-associated myelopathy carriers (1.4- to 2.8-fold). Prior treatment of the endothelial cell monolayer with recombinant interferon gamma (50 IU/mL) enhanced the T cell-endothelial cell adhesion in both the controls and patients with HTLV-I-associated myelopathy. However, values after prior treatment in the patients with HTLV-I-associated myelopathy were significantly higher than those in seronegative controls and carriers. The results suggest that the significantly increased T cell-endothelial cell adherence may be related to the initial stages of lymphocyte migration from the blood to the central nervous system in patients with HTLV-I-associated myelopathy.

Active production of anti-human T-lymphotropic virus type I (HTLV-I) IgM antibody in HTLV-I-associated myelopathy.

We investigated the presence of anti-human T-lymphotropic virus type I (HTLV-I) IgM in sera and cerebrospinal fluid from patients with HTLV-I-associated myelopathy (HAM) by Western blot analysis. Analyses of 36 serum samples revealed that most patients (31/36; 86.1%) had anti-HTLV-I IgM, whereas only four of 23 (17.4%) HTLV-I carriers had it. In studies of cerebrospinal fluid, anti-HTLV-I IgM was detected in 24 of 36 (66.7%) HAM patients, whereas none was detected in nine HTLV-I carriers. The differences were statistically significant (p less than 0.01). These results suggest that persistent active replication of HTLV-I occurs in the central nervous system as well as in the peripheral blood of HAM patients, and may contribute to the development of HAM.

Expression of mRNA coding for pituitary hormones and pituitary-specific transcription factor in the pituitary gland of the rdw rat with hereditary dwarfism.

The rdw rat (gene symbol: rdw) with hereditary dwarfism has been shown immunohistochemically to have subnormal numbers not only of GH- but also of prolactin- and thyrotrophin-positive cells. To characterize the dwarfism of this strain, the expression of pituitary hormone mRNAs was examined by Northern hybridization. The pituitary gland in the rdw rat expressed 30-100 times less GH and prolactin mRNAs than normal controls, whereas mRNAs for pro-opiomelanocortin and the alpha subunit of rat glycoprotein hormone revealed a significant increase. There was a non-significant difference in rat LH-beta subunit and FSH-beta subunit between normal and rdw rats. The suppressed expression of a pituitary-specific transcription factor, Pit-1, is considered to cause hereditary dwarfism in mouse strains Snell and Jackson, whose phenotypes resemble those of the rdw rat. In this study, however, no difference in mRNA expression for Pit-1 was found between rdw rats and controls. This work indicates that the rdw rat may not have the same genotype as the phenotypically similar dwarf mice, Snell, Jackson and Ames.

Polymorphism of the polyalanine tract of thyroid transcription factor-2 gene in patients with thyroid dysgenesis.

OBJECTIVE: One of the thyroid-specific transcription factors, thyroid transcription factor-2 (TTF-2), performs a crucial role in the development of the thyroid gland. We performed genetic analysis of the TITF2 gene (encoding TTF-2) in patients with thyroid dysgenesis. METHODS: By direct sequencing of the PCR products of TITF2, we screened the genomic DNA from 46 patients with thyroid dysgenesis (five had agenesis, six had hypoplasia, 15 had ectopy, and 20 were undetermined). We also studied the transcriptional activities of TITF2 by co-expressing the luciferase gene directed by the human thyroglobulin gene promoter. RESULTS: Human TITF2 consists of a forkhead domain, a polyalanine tract, and unique C-terminal residues. In one of the patients with an ectopic sublingual thyroid, we found a polyalanine tract of 11 alanine residues on one chromosome instead of the 14 alanine residues found in normal controls. In one patient with hypoplasia, the polyalanine tract consisted of 12 heterozygous alanine residues. The reduced polyalanine tracts were not detected in 101 normal individuals. However, the expression study showed that the transcriptional activities of TITF2 with reduced polyalanine-tract lengths were equal to that of TITF2 with an unreduced polyalanine tract. CONCLUSION: These results suggest that the polymorphism of the polyalanine tract of TITF2 is not a frequent cause of developmental defects of the human thyroid gland.

A preliminary survey of extended-spectrum beta-lactamases (ESBLs) in clinical isolates of Klebsiella pneumoniae and Escherichia coli in Japan.

We conducted a survey of extended-spectrum beta-lactamases (ESBLs) among 16805 Escherichia coli and 9794 Klebsiella pneumoniae clinical isolates recovered from 196 separate medical institutions during the period January 1997 to January 1998. Using the criteria for minimal inhibitory concentrations (MICs) of oxyimino-cephalosporins of >/=8 microg ml(-1) and confirmation by double-disk test, we detected 15 E. coli and 34 K. pneumoniae isolates producing ESBLs. Genotypes of ESBLs determined by PCR with type-specific primers included one TEM-derived and 24 SHV-derived ESBLs, in addition to 24 Toho-1-type ESBLs, one of the major types of ESBLs reported in Japan. Nucleotide sequence analysis of SHV-specific PCR products revealed that SHV-12 was the dominant type of SHV-derived ESBL. In addition, we also identified TEM-26 and SHV-2. This is the first report characterizing TEM- and SHV-derived ESBLs in Japan.

Role of multiple efflux pumps in Escherichia coli in indole expulsion.

Escherichia coli chromosome encodes several multidrug transporters. Despite their protective function against antibacterial agents, the specific physiological actions of these transporters are not fully understood. E. coli produces indole, a metabolite of tryptophan, under physiological conditions. Defined inactivation of the acrEF gene, the product of which is known as an energy-dependent multiple drug efflux pump, decreased indole excretion while reintroduction of the acrEF gene restored it. A DeltaacrEF mutant accumulated more intracellular indole than the parent. This mutant was more susceptible to the growth-inhibitory effect of indole than the parent. These results indicate that the AcrEF system plays a significant role in indole efflux.

Four critical aspartic acid residues potentially involved in the catalytic mechanism of Escherichia coli K-12 WaaR.

Escherichia coli K-12 WaaR is a non-processive alpha-1,2 glucosyltransferase, involved in the synthesis of the R-core of lipopolysaccharide. WaaR possesses the four conserved structural regions I, II, III and IV, each presumably involved in the mechanistic function in catalysis. Regions I and III contain the pair of strictly conserved Asp residues. Asp-129, 131 (region I) and 215, 217 (region III) of WaaR were individually converted to Asn by the site-directed mutagenesis of the waaR gene. All mutated enzymes were inactive, supporting the model for an alpha-glycosyl transfer reaction where the pair of strictly conserved aspartic acid residues in regions I and III play a critical role in the catalytic function.

Pathological effect of synthetic cereulide, an emetic toxin of Bacillus cereus, is reversible in mice.

Cereulide is the causative toxin of the emetic type of food-borne illness caused by Bacillus cereus. This toxin was previously shown to be associated with fulminant liver failure in a human case. Mice were injected i.p. with synthetic cereulide and the development of histopathological changes was examined. Hepatocytes showed mitochondrial swelling with loss of cristae, and dose-dependent increase of small fatty droplets. These microsteatotic hepatocytes were distributed mainly in the pericentral area. At higher cereulide doses, massive degeneration of hepatocytes occurred. The serum values of hepatic enzymes were highest on days 2-3 after the inoculation of cereulide, and rapidly decreased thereafter. General recovery from the pathological changes and regeneration of hepatocytes was observed after 4 weeks.

Presence of serum anti-human T-lymphotropic virus type I (HTLV-I) IgM antibodies means persistent active replication of HTLV-I in HTLV-I-associated myelopathy.

We investigated serum IgM antibodies against human T-lymphotropic virus type I (HTLV-I) in 29 HTLV-I associated myelopathy (HAM) patients and 34 HTLV-I carriers, using western blot analysis. Anti-HTLV-I IgM was detected in all 6 post-transfusional HAM patients and in 19 of 23 (83%) HAM patients with no history of blood transfusion, but in only 4 of 21 (19%) HTLV-I carriers. In HAM patients, HTLV-I proviral DNA integrated into peripheral blood lymphocyte (PBL) was detected by Southern blot analysis in all of the 6 (100%) and 18 of the 23 (78%). In contrast, it was detected in only 2 of 25 (8%) HTLV-I carriers. For the serum anti-HTLV-I IgM and HTLV-I provirus in PBL, the differences between the HAM and HTLV-I carriers were statistically significant (P less than 0.01). Our data indicate that the increased HTLV-I proviral DNA in PBL is produced by the persistent active replication of HTLV-I in HAM. Furthermore, Southern blot analysis showed intense bands in HAM patients with histories of blood transfusion, in whom the progression of the disease had been rapid. We conclude that the persistent active replication of HTLV-I is an important factor in the pathogenesis of HAM.

Interferon-alpha treatment in HTLV-I-associated myelopathy. Studies of clinical and immunological aspects.

We treated 17 patients with HTLV-I-associated myelopathy (HAM) with interferon-alpha (IFN-alpha) in an open, nonrandomized, uncontrolled study. They were administered 1.5-9.0 x 10(6) international units of IFN-alpha daily for 4 weeks, and 4 patients showed a marked clinical response, 7 showed a moderate response and the others did not show any clinical response. Increased unstimulated (spontaneous) peripheral blood lymphocyte (PBL) proliferation was observed in all patients who were measured lymphocyte transformation. Spontaneous PBL proliferation was significantly inhibited by IFN-alpha treatment (P less than 0.01), whereas anti-HTLV-I-antibodies did not show any significant changes. Likewise, decreased stimulation indices to phytohemagglutinin (SI) due to increased spontaneous PBL proliferation were significantly increased after IFN-alpha treatment (P less than 0.01). In the patients who showed marked clinical responses, the changes of SI in IFN-alpha treatment were higher than those in other patients. These data indicate that further studies are warranted for evaluation of IFN-alpha treatment of HAM in a randomized, controlled study.

Heparin treatment in patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy: a preliminary study.

Ten patients with HTLV-I-associated myelopathy (HAM) were treated in an uncontrolled preliminary trial of heparin. In 7 patients, motor dysfunction improved substantially and the effect continued for more than a month after the discontinuation of therapy. Sensory and urinary disturbances also improved in 3 of 4 and in 2 of 10 patients, respectively. Heparin did not alter the subsets of peripheral blood lymphocytes nor the titers of anti-HTLV-I antibodies in serum and cerebrospinal fluid. Spontaneous proliferation of peripheral blood lymphocytes, however, was depressed significantly (P < 0.05) in all cases. Heparin therapy has some advantages in cost, ease of administration and fewer side effects compared to other therapies such as plasmapheresis and interferon-alpha. We conclude that heparin can be administered safely to HAM, and that a double-blind placebo-controlled trial is warranted to determine its efficacy in HAM.