Nationwide genome surveillance of carbapenem-resistant Pseudomonas aeruginosa in Japan

Japan is a country with an approximate 10% prevalence rate of carbapenem-resistant Pseudomonas aeruginosa (CRPA). Currently, a comprehensive overview of the genotype and phenotype patterns of CRPA in Japan is lacking. Herein, we conducted genome sequencing and quantitative antimicrobial susceptibility testing for 382 meropenem-resistant CRPA isolates that were collected from 78 hospitals across Japan from 2019 to 2020. CRPA exhibited susceptibility rates of 52.9%, 26.4%, and 88.0% against piperacillin-tazobactam, ciprofloxacin, and amikacin, respectively, whereas 27.7% of CRPA isolates was classified as difficult-to-treat resistance P. aeruginosa. Of the 148 sequence types detected, ST274 (9.7%) was predominant, followed by ST235 (7.6%). The proportion of urine isolates in ST235 was higher than that in other STs (P = 0.0056, χ2 test). Only 4.1% of CRPA isolates carried the carbapenemase genes: blaGES (2) and blaIMP (13). One ST235 isolate carried the novel blaIMP variant blaIMP-98 in the chromosome. Regarding chromosomal mutations, 87.1% of CRPA isolates possessed inactivating or other resistance mutations in oprD, and 28.8% showed mutations in the regulatory genes (mexR, nalC, and nalD) for the MexAB-OprM efflux pump. Additionally, 4.7% of CRPA isolates carried a resistance mutation in the PBP3-encoding gene ftsI. The findings from this study and other surveillance studies collectively demonstrate that CRPA exhibits marked genetic diversity and that its multidrug resistance in Japan is less prevailed than in other regions. This study contributes a valuable data set that addresses a gap in genotype/phenotype information regarding CRPA in the Asia-Pacific region, where the epidemiological background markedly differs between regions.

Oral and rectal colonization of methicillin-resistant Staphylococcus aureus in long-term care facility residents and their association with clinical status

Staphylococcus aureus is a commensal bacterium in humans, but it sometimes causes opportunistic infectious diseases such as suppurative skin disease, pneumonia, and enteritis. Therefore, it is important to determine the prevalence of S. aureus and methicillin-resistant S. aureus (MRSA) in individuals, especially older adults. In this study, we investigated the prevalence of S. aureus and MRSA in the oral cavity and feces of residents in long-term care facilities (LTCFs). S. aureus was isolated from the oral cavity of 61/178 (34.3%) participants, including 28 MRSA-positive participants (15.7%), and from the feces of 35/127 (27.6%) participants, including 16 MRSA-positive participants (12.6%). S. aureus and MRSA were isolated from both sites in 19/127 individuals (15.0%) and 10/127 individuals (7.9%), respectively. Among 19 participants with S. aureus isolation from both sites, 17 participants showed the same sequence type (ST) type. Then, we analyzed the correlation of S. aureus and MRSA in the oral cavity and rectum with the participant's condition. S. aureus and MRSA positivity in the oral cavity was significantly related to tube feeding, while there was no correlation of rectal S. aureus/MRSA with any factors. Our findings regarding the oral inhabitation of MRSA and its risk factors indicate the importance of considering countermeasures against MRSA infection in LTCFs.

Comparison of disease and economic burden between MRSA infection and MRSA colonization in a university hospital: a retrospective data integration study

BACKGROUND

Although there is a growing concern and policy regarding infections or colonization caused by resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), the prognosis of MRSA infections compared to that of methicillin-susceptible Staphylococcus aureus (MSSA) infections remains controversial. Moreover, there have not been any studies comparing both the burden of disease and its impact on the healthcare economy between MRSA infection and colonization while adjusting for confounding factors. These comparisons are crucial for developing effective infection control measures and healthcare policies. We aimed to compare the disease and economic burden between MRSA and MSSA infections and between MRSA infection and colonization.

METHODS

We retrospectively investigated data of 496 in-patients with MRSA or MSSA infections and of 1178 in-patients with MRSA infections or MRSA colonization from a university hospital in Japan from 2016 to 2021. We compared in-hospital mortality, length of stay, and hospital charges between in-patients with MRSA and MSSA infections and those with MRSA infections and MRSA colonization using multiple regressions. We combined surveillance data, including all microbiological test results, data on patients with infections, treatment histories, and clinical outcomes, to create the datasets.

RESULTS

There was no statistically significant difference in in-hospital mortality rates between matched MRSA vs. MSSA infections and MRSA infection vs. colonization. On the contrary, the adjusted effects of the MRSA infection compared to those of MSSA infection on length of stay and hospital charges were 1.21-fold (95% confidence interval [CI] 1.03-1.42, P = 0.019) and 1.70-fold (95% CI 1.39-2.07, P < 0.00001), respectively. The adjusted effects of the MRSA infection compared to those of MRSA colonization on length of stay and hospital charges were 1.41-fold (95% CI 1.25-1.58, P < 0.00001) and 1.53-fold (95% CI 1.33-1.75, P < 0.00001), respectively. Regarding confounding factors, hemodialysis or hemofiltration was consistently identified and adjusted for in the multiple regression analyses comparing MRSA and MSSA infections, as well as MRSA infection and MRSA colonization.

CONCLUSIONS

MRSA infection was associated with longer length of stay and higher hospital charges than both MSSA infection and MRSA colonization. Furthermore, hemodialysis or hemofiltration was identified as a common underlying factor contributing to increased length of stay and hospital charges.

Antimicrobial use and combination of resistance phenotypes in bacteraemic Escherichia coli in primary care: a study based on Japanese national data in 2018

BACKGROUND

Antimicrobial use (AMU) in primary care is a contributing factor to the emergence of antimicrobial-resistant bacteria. We assessed the potential effects of AMU on the prevalence of a combination of resistance phenotypes in bacteraemic Escherichia coli in outpatient care settings between primary care facilities ('clinics') and hospitals.

METHODS

Population-weighted total AMU calculated from the national database was expressed as DDDs per 1000 inhabitants per day (DID). National data for all routine microbiological test results were exported from the databases of a major commercial clinical laboratory, including 16 484 clinics, and the Japan Nosocomial Infections Surveillance, including 1947 hospitals. AMU and the prevalence of combinations of resistance phenotypes in bacteraemic E. coli isolates were compared between clinics and hospitals.

RESULTS

The five most common bacteria isolated from patients with bacteraemia were the same in clinics, outpatient settings and inpatient settings in hospitals, with E. coli as the most frequent. Oral third-generation cephalosporins and fluoroquinolones were the top two AMU outpatient drugs, except for macrolides, and resulted in at least three times higher AMU in clinics than in hospitals. The percentage of E. coli isolates resistant to both drugs in clinics (18.7%) was 5.6% higher than that in hospitals (13.1%) (P < 10-8).

CONCLUSIONS

Significant AMU, specifically of oral third-generation cephalosporins and fluoroquinolones, in clinics is associated with a higher prevalence of E. coli isolates resistant to both drugs. This study provides a basis for national interventions to reduce inappropriate AMU in primary care settings.

Exploring the effects of antimicrobial treatment on the gut and oral microbiomes and resistomes from elderly long-term care facility residents via shotgun DNA sequencing

Monitoring antibiotic-resistant bacteria (ARB) and understanding the effects of antimicrobial drugs on the human microbiome and resistome are crucial for public health. However, no study has investigated the association between antimicrobial treatment and the microbiome-resistome relationship in long-term care facilities, where residents act as reservoirs of ARB but are not included in the national surveillance for ARB. We conducted shotgun metagenome sequencing of oral and stool samples from long-term care facility residents and explored the effects of antimicrobial treatment on the human microbiome and resistome using two types of comparisons: cross-sectional comparisons based on antimicrobial treatment history in the past 6 months and within-subject comparisons between stool samples before, during and 2-4 weeks after treatment using a single antimicrobial drug. Cross-sectional analysis revealed two characteristics in the group with a history of antimicrobial treatment: the archaeon Methanobrevibacter was the only taxon that significantly increased in abundance, and the total abundance of antimicrobial resistance genes (ARGs) was also significantly higher. Within-subject comparisons showed that taxonomic diversity did not decrease during treatment, suggesting that the effect of the prescription of a single antimicrobial drug in usual clinical treatment on the gut microbiota is likely to be smaller than previously thought, even among very elderly people. Additional analysis of the detection limit of ARGs revealed that they could not be detected when contig coverage was <2.0. This study is the first to report the effects of usual antimicrobial treatments on the microbiome and resistome of long-term care facility residents.

National genomic surveillance integrating standardized quantitative susceptibility testing clarifies antimicrobial resistance in Enterobacterales

Antimicrobial resistance is a global health concern; Enterobacterales resistant to third-generation cephalosporins (3GCs) and carbapenems are of the highest priority. Here, we conducted genome sequencing and standardized quantitative antimicrobial susceptibility testing of 4,195 isolates of Escherichia coli and Klebsiella pneumoniae resistant to 3GCs and Enterobacterales with reduced meropenem susceptibility collected across Japan. Our analyses provided a complete classification of 3GC resistance mechanisms. Analyses with complete reference plasmids revealed that among the blaCTX-M extended-spectrum β-lactamase genes, blaCTX-M-8 was typically encoded in highly similar plasmids. The two major AmpC β-lactamase genes were blaCMY-2 and blaDHA-1. Long-read sequencing of representative plasmids revealed that approximately 60% and 40% of blaCMY-2 and blaDHA-1 were encoded by such plasmids, respectively. Our analyses identified strains positive for carbapenemase genes but phenotypically susceptible to carbapenems and undetectable by standard antimicrobial susceptibility testing. Systematic long-read sequencing enabled reconstruction of 183 complete plasmid sequences encoding three major carbapenemase genes and elucidation of their geographical distribution stratified by replicon types and species carrying the plasmids and potential plasmid transfer events. Overall, we provide a blueprint for a national genomic surveillance study that integrates standardized quantitative antimicrobial susceptibility testing and characterizes resistance determinants.

Distribution, Trends, and Antimicrobial Susceptibility of Bacteroides, Clostridium, Fusobacterium, and Prevotella Species Causing Bacteremia in Japan During 2011-2020: A Retrospective Observational Study Based on National Surveillance Data

Background

The increasing prevalence of anaerobic bacteremia is a major concern worldwide and requires longitudinal monitoring.

Methods

We present one of the largest and longest longitudinal studies on the prevalence and antimicrobial resistance of Bacteroides, Clostridium, Fusobacterium, and Prevotella spp. isolated from blood culture samples using national comprehensive surveillance data in Japan during 2011-2020 as part of the Japan Nosocomial Infections Surveillance.

Results

Data for 41 949 Bacteroides spp., 40 603 Clostridium spp., 7013 Fusobacterium spp., and 5428 Prevotella spp. isolates were obtained. The incidences of bacteremia caused by Bacteroides fragilis, Clostridium perfringens, and Fusobacterium nucleatum significantly increased during the period (P < .0001). Among the 20 species analyzed, 18 showed no significant changes in susceptibility over time, including B. fragilis, C perfringens, and F. nucleatum. However, resistance to clindamycin increased in B. thetaiotaomicron (P = .0312), and resistance to ampicillin increased in B. ovatus (P = .0008).

Conclusions

Our comprehensive national surveillance data analysis demonstrated a continuous increase in the incidence of anaerobic bacteremia, particularly in B. fragilis, C. perfringens, and F. nucleatum. This may be linked to the increasing number of colorectal cancer cases or advancing methods for species identification and susceptibility testing, requiring cautious interpretation. The discovery of an upsurge in anaerobic bacteremia and potential alterations in susceptibility highlights the necessity for more extensive studies in this field.

Association between the proportion of laparoscopic approaches for digestive surgeries and the incidence of consequent surgical site infections, 2009-2019: A retrospective observational study based on national surveillance data in Japan

BACKGROUND

Surgical site infections (SSIs) are among the most common healthcare-associated infections. Laparoscopy is increasingly being used in various surgical procedures. However, no study has examined the association between the proportion of laparoscopic procedures and the incidence of SSIs in digestive surgery using nationwide surveillance data.

METHODS

We retrospectively investigated national SSI surveillance data from the Japan Nosocomial Infections Surveillance between 2009 and 2019. The annual trend of the SSI rate and the proportion of laparoscopic procedures were assessed, focusing on five major digestive surgeries. This was based on data from 109,544 (appendix surgery), 206,459 (gallbladder surgery), 60,225 (small bowel surgery), 363,677 (colon surgery), and 134,695 (rectal surgery) procedures. The effect of a 10% increase in the proportion of laparoscopic procedures on the reduction of the SSI rate was estimated using mixed-effect logistic regression.

FINDINGS

The average SSI rate of the five digestive surgeries decreased from 11.8% in 2009 to 8.1% in 2019. The proportion of laparoscopic procedures in each of the five digestive surgeries increased continuously (p<0.001). The SSI rate for laparoscopic procedures was always lower than that for open procedures. The results were consistent between all and core hospitals participating in the surveillance. The odds ratios of the 10% increase in the proportion of laparoscopic procedures for five digestive surgeries were always <0.950 (p<0.001).

CONCLUSION

An increase in the proportion of laparoscopic procedures was associated with a reduction in the SSI rate in digestive surgeries.

Oral and Rectal Colonization by Antimicrobial-Resistant Gram-Negative Bacteria and Their Association with Death among Residents of Long-Term Care Facilities: A Prospective, Multicenter, Observational, Cohort Study

INTRODUCTION

The prevalence of antimicrobial-resistant bacteria (ARB) in long-term care facilities (LTCFs) remains unclear. Furthermore, the effect of ARB colonization on the clinical outcomes of LTCF residents has not been explored.

METHODS

We conducted a prospective multicenter cohort study and investigated the residents (N = 178) of six Japanese LTCFs (three Welfare Facilities for the Elderly Requiring Long-term Care and three Geriatric Health Service Facilities) for oral and rectal carriage of ARB. The clinical outcomes of the residents were evaluated based on isolating bacterial strains and subjecting them to whole-genome sequencing.

RESULTS

Of the 178 participants, 32 belonging to Geriatric Health Service Facilities with no information on their clinical outcome were excluded, and the remaining 146 were followed up for at most 21 months. Extended-spectrum β-lactamases (ESBL)-producing Enterobacterales and Pseudomonas aeruginosa were detected in 42.7% (n = 76) and 2.8% (n = 5) of the rectal swabs and 5.6% (n = 10) and 3.4% (n = 6) of the oral swabs, respectively. Detection of ARB in the oral and rectal cavities showed remarkable association with enteral nutrition. Further, P. aeruginosa was significantly associated with an increase in mortality of the residents, but there were not significant association between ESBL-producing Enterobacterales and mortality. Core-genome phylogeny of P. aeruginosa revealed a wide-spread distribution of the isolated strains across the phylogeny, which included a cluster of ST235 strains with substantially higher biofilm formation ability than the other isolated P. aeruginosa strains.

DISCUSSION/CONCLUSION

This study is the first to investigate the carriage of both oral and rectal ARB, genomic relatedness and determinants of antimicrobial resistance in isolated strains, and clinical outcomes of LTCF residents. Our study provides the first direct evidence for the burden of antimicrobial resistance in LTCFs.

Distribution, trends, and antifungal susceptibility of Candida species causing candidemia in Japan, 2010-2019: A retrospective observational study based on national surveillance data

The increasing incidence of candidemia and the emergence of drug-resistant Candida species are major concerns worldwide. Therefore, long-term surveillance studies are required. Here, we provide one of the largest longitudinal overviews of the trends in the prevalence of Candida species using national data of 57 001 candidemia isolates obtained from more than 2000 hospitals for the 2010-2019 period in the Japan Nosocomial Infections Surveillance database. The proportion of Candida species, except Candida krusei and Candida guilliermondii, was almost the same during the study period. The proportion of C. guilliermondii surpassed that of C. krusei in 2014. The incidence of candidemia due to C. albicans (p < 0.0001), C. parapsilosis (p = 0.0002), and C. tropicalis (p < 0.0001) have decreased significantly over this period. Azole susceptibility of Candida tropicalis was low, with 17.8% of isolates resistant to fluconazole and 13.5% resistant to voriconazole. The micafungin susceptibility of C. glabrata was low, with 8.0% of isolates showing resistance. The resistance rate of C. krusei toward amphotericin B fluctuated considerably (between 3.2% and 35.7%) over this period. The incidence rate of candidemia caused by C. parapsilosis and C. guilliermondii in hospitals responsible for bone marrow transplantation was significantly higher than that in other hospitals. Overall, our study suggests that in Japan, the species distribution of Candida was almost the same in this period and similar to that reported in North America and Europe. A relatively high resistance to azoles and micafungin was observed in C. glabrata, C. tropicalis, and C. krusei isolates, which require continued surveillance.

The use of topical antibiotics based on National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) Open Data in 2017

The national action plan on antimicrobial resistance (AMR) in Japan emphasizes the importance of understanding antimicrobial use (AMU). Some studies have been conducted on oral and parenteral AMU in Japan. However, there are few studies on the use of topical antimicrobials, such as in dermatology and ophthalmology. Therefore, the purpose of this study was to investigate topical AMU in Japan. Data on AMU in dermatology and ophthalmology were obtained from the 2017 National Database of Health Insurance Claims and Specific Health Checkups of Japan Open Data. The number of dermatological products used was 58,396,530 in 2017. The proportion of betamethasone/gentamicin was 50.5% and that of gentamicin 16.7%, whereas that of the ingredient quantity in gentamicin was 7.8%. It was suggested that topical AMU should be evaluated by the number of products. The number of ophthalmological products used was 24,655,653 in 2017, and the proportion of quinolones was 95.9%. The high prescription rate of quinolones may cause an increase in quinolone resistance in the ophthalmologic field. Topical AMU, which is a potential "blind spot" in the measures against AMR, needs to be continuously monitored, together with systemic AMU.

Geographical distribution of Enterobacterales with a carbapenemase IMP-6 phenotype and its association with antimicrobial use: An analysis using comprehensive national surveillance data on antimicrobial resistance

Enterobacterales resistant to carbapenems, a class of last-resort antimicrobials, are ranked as an “urgent” and “critical” public health hazard by CDC and WHO. IMP-type carbapenemase-containing Enterobacterales are endemic in Japan, and bla_IMP-6 is one of the notable carbapenemase genes responsible for the resistance. The gene is plasmid-encoded and confers resistance to meropenem, but not to imipenem. Therefore, IMP-6-producing Enterobacterales isolates are occasionally overlooked in clinical laboratories and are referred to as ‘stealth-type’. Since previous reports in Japan were confined only to some geographical regions, their distribution across prefectures and the factors affecting the distribution remain unclear. Here, we revealed the dynamics of the geographical distribution of Enterobacterales with IMP-6 phenotype associated with antimicrobial use in Japan. We utilized comprehensive national surveillance data of all routine bacteriological test results from more than 1,400 hospitals in 2015 and 2016 to enumerate Escherichia coli and Klebsiella pneumoniae isolates with the antimicrobial susceptibility pattern (phenotype) characteristic of IMP-6 (imipenem susceptible, meropenem resistant), and to tabulate the frequency of isolates with the phenotype for each prefecture. Isolates were detected in approximately half of all prefectures, and combined analysis with the national data of antimicrobial usage revealed a statistically significant association between the frequency and usage of not carbapenems but third-generation cephalosporins (p = 0.006, logistic mixed-effect regression) and a weaker association between the frequency and usage of fluoroquinolones (p = 0.043). The usage of third-generation cephalosporins and fluoroquinolones may select the strains with the IMP-6 phenotype, and contribute to their occasional spread. We expect the findings will promote antimicrobial stewardship to reduce the spread of the notable carbapenemase gene.

Japan Nosocomial Infections Surveillance (JANIS): Current Status, International Collaboration, and Future Directions for a Comprehensive Antimicrobial Resistance Surveillance System

Japan Nosocomial Infections Surveillance (JANIS) is one of the largest national antimicrobial resistance (AMR) surveillance systems in the world. The JANIS Clinical Laboratory division collects comprehensive specimen-based data from diagnostic microbiology laboratories of participating hospitals to monitor the isolation rate of 11 major bacteria and specific AMR bacteria, and creates antibiograms of approximately 20 bacterial species. Data on the JANIS web database system are also annually tabulated and shared with the WHO Global Antimicrobial Resistance Surveillance System. To create a network of international AMR surveillance systems among Asian countries, Japan is developing an international web database system named ASIan Antimicrobial Resistance Surveillance Network (ASIARS-Net) based on the JANIS system; ASIARS-Net is an open-source database and confidentially available at almost no cost. JANIS continues to evolve in multiple directions; some are discussed at the end of this review.

Comparison of de-duplication methods used by WHO Global Antimicrobial Resistance Surveillance System (GLASS) and Japan Nosocomial Infections Surveillance (JANIS) in the surveillance of antimicrobial resistance

A major issue in the surveillance of antimicrobial resistance (AMR) is "de-duplication" or removal of repeated isolates, for which there exist multiple methods. The World Health Organization (WHO) Global Antimicrobial Resistance Surveillance System (GLASS) requires de-duplication by selecting only the first isolate of a given bacterial species per patient per surveillance period per specimen type per age group, gender, and infection origin stratification. However, no study on the comparative application of this method has been reported. The objective of this study was to evaluate differences in data tabulation between the WHO GLASS and the Japan Nosocomial Infections Surveillance (JANIS) system, which counts both patients and isolates after removing repeated isolates of the same bacterial species isolated from a patient within 30 days, regardless of specimen type, but distinguishing isolates with change of antimicrobial resistance phenotype. All bacterial data, consisting of approximately 8 million samples from 1795 Japanese hospitals in 2017 were exported from the JANIS database, and were tabulated using either the de-duplication algorithm of GLASS, or JANIS. We compared the tabulated results of the total number of patients whose blood and urine cultures were taken and of the percentage of resistant isolates of Escherichia coli for each priority antibiotic. The number of patients per specimen type tabulated by the JANIS method was always smaller than that of GLASS. There was a small (< 3%) difference in the percentage of resistance of E. coli for any antibiotic between the two methods in both out- and inpatient settings and blood and urine isolates. The two tabulation methods did not show considerable differences in terms of the tabulated percentages of resistance for E. coli. We further discuss how the use of GLASS tabulations to create a public software and website that could help to facilitate the understanding of and treatment against AMR.

Aeromonas dhakensis is not a rare cause of Aeromonas bacteremia in Hiroshima, Japan

Aeromonas dhakensis, a newly recognized species, is often misidentified as A. hydrophila, A. veronii, or A. caviae by commercial phenotypic tests. Limited data about A. dhakensis are available in Japan. We retrospectively analyzed the patients with monomicrobial Aeromonas bacteremia at Hiroshima University Hospital from January 2011 to December 2017, and species re-identification was conducted using rpoD and gyrB gene sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. Of the 19 strains from blood isolates, A. caviae (n = 9, 47.4%), A. dhakensis (n = 4, 21.1%), A. hydrophila (n = 3, 15.8%), and A. veronii (n = 3, 15.8%) were re-identified. A. dhakensis was phenotypically misidentified as A. hydrophila (n = 3, 75%) or A. sobria (n = 1, 25%). A. dhakensis was also misidentified as A. caviae (n = 2, 50%), A. hydrophila (n = 1, 25%), and A. jandaei (n = 1, 25%) in MALDI-TOF MS system. Malignancies (n = 12, 63.2%) and liver cirrhosis (n = 7, 36.8%) were common comorbidities. Biliary tract infection was the most frequent source of Aeromonas bacteremia (n = 11, 57.9%). The major source of A. dhakensis bacteremia was also biliary tract infection (n = 3, 75%), and the 14-day infection-related mortality of A. dhakensis was 25%. A. dhakensis isolates showed similar clinical characteristics, antimicrobial susceptibility, and mortality with those of other Aeromonas species isolates. This study demonstrated that A. dhakensis is not a rare cause of Aeromonas bacteremia, but is often misidentified as A. hydrophila in Hiroshima, Japan. Further studies should be conducted to identify the geographical distribution and clinical impact of A. dhakensis in Japan.

Prosthetic Valve Endocarditis Caused by ST8 SCCmecIVl Type Community-associated Methicillin-resistant Staphylococcus aureus

The emergence of a Japan-intrinsic community associated methicillin-resistant Staphylococcus aureus strain (CA-MRSA/J) has been reported. A 70-year-old man with recurrent colon cancer and a history of mitral valve replacement was admitted to the hospital in a state of shock. He was diagnosed with prosthetic valve endocarditis (PVE) caused by MRSA and underwent cardiac surgery. The MRSA isolates belonged to multilocus sequence type 8 and carried staphylococcal cassette chromosome mec IVl and the genes of toxic shock syndrome toxin-1, enterotoxin C, and enterotoxin L. These characteristics indicated a CA-MRSA/J clone. This is the first reported case of PVE caused by CA-MRSA/J.

The first multi-centre point-prevalence survey in four Japanese university hospitals

BACKGROUND

The Japanese government adopted a national action plan on antimicrobial resistance, which aims to reduce drug-resistant pathogens and antimicrobial use. A point-prevalence survey (PPS) is a useful surveillance method to gain information about hospital epidemiology; however, no multi-centre PPS has previously been performed in Japan.

AIM

To investigate general information about hospital epidemiology, healthcare-associated infections (HCAIs), and antimicrobial use in multiple Japanese university hospitals.

METHODS

In July 2016, a multi-centre PPS was conducted using a standardized protocol at four university hospitals in Japan.

FINDINGS

A total of 3199 patients were included. Median age and duration of hospital stay were 64 years and 10 days, respectively. A total of 246 (7.7%; 95% confidence interval (CI): 6.8-8.7) patients had 256 active HCAIs, and 933 (29.2%; 95% CI: 27.6-30.8) patients received 1318 antimicrobials. Pneumonia and gastrointestinal system infection were the most common HCAIs (N = 42, 16.4%), and Enterobacteriaceae (N = 49, 30.8%) were the predominant causative organisms. Carbapenems (N = 52, 17.8%), anti-MRSA medications, and cephems with antipseudomonal activity were the most frequently prescribed antimicrobials for HCAIs. As surgical prophylaxis, 46 of 278 antimicrobials (16.5%) were administered orally. Proportions of HCAI and antimicrobial use in each hospital ranged from 4.8% to 9.5% and 19.3%-35.0%, respectively.

CONCLUSION

This multi-centre PPS recorded detailed HCAI data and distinct antimicrobial use in Japanese university hospitals. Further surveillance is necessary to reduce HCAIs and formulate feasible plans to achieve the national action plan on antimicrobial resistance.

Pharmacokinetics of piperacillin-tazobactam in plasma, peritoneal fluid and peritoneum of surgery patients, and dosing considerations based on site-specific pharmacodynamic target attainment

Piperacillin-tazobactam (PIP-TAZ) is commonly used to treat intraabdominal infections; however, its penetration into abdominal sites is unclear. A pharmacokinetic analysis of plasma, peritoneal fluid, and peritoneum drug concentrations was conducted to simulate dosing regimens needed to attain the pharmacodynamic target in abdominal sites. PIP-TAZ (4 g-0.5 g) was intravenously administered to 10 patients before abdominal surgery for inflammatory bowel disease. Blood, peritoneal fluid, and peritoneum samples were obtained at the end of infusion (0.5 h) and up to 4 h thereafter. PIP and TAZ concentrations were measured, both noncompartmental and compartmental pharmacokinetic parameters were estimated, and a simulation was conducted to evaluate site-specific pharmacodynamic target attainment. The mean peritoneal fluid:plasma ratios in the area under the drug concentration-time curve (AUC) were 0.75 for PIP and 0.79 for TAZ, and the mean peritoneal fluid:plasma ratios in the AUC were 0.49 for PIP and 0.53 for TAZ. The mean PIP:TAZ ratio was 8.1 at both peritoneal sites. The regimens that achieved a bactericidal effect with PIP (time above minimum inhibitory concentration [MIC] >50%) at both peritoneal sites were PIP-TAZ 4.5 g twice daily for an MIC of 8 mg/L, as well as 4.5 g three times daily, and 3.375 g four times daily for an MIC of 16 mg/L. These findings clarify the peritoneal pharmacokinetics of PIP-TAZ, and help consider the dosing regimens for intraabdominal infections based on site-specific pharmacodynamic target attainment.

Comparative efficacies of daptomycin, vancomycin, and linezolid in experimental enterococcal peritonitis

Enterococci have become increasingly important pathogens for nosocomial infection (e.g. bacteremia, intra-abdominal infection, endocarditis, etc.), related to their intrinsic resistance to many antibiotics. Although the in vitro susceptibility of daptomycin (DAP) against Enterococci is well established, the Food and Drug Administration has only approved its use for complicated skin and skin structure infections induced by Enterococcus faecalis. In this study we evaluated the potential therapeutic application of DAP in a murine model of enterococcal experimental peritonitis. Mice were injected intraperitoneally with 4 × 10¹⁰ colony-forming units of Enterococcus faecium. DAP alone, DAP combined with ampicillin, vancomycin, or linezolid were administered 2 h after enterococcal inoculation and examined the survival, viable bacteria counts, the level of KC/CXCL1 in the peritoneal fluid. The viable bacteria counts in the peritoneal fluid of the DAP- or DAP plus ampicillin-treated groups were decreased significantly compared to those of the vancomycin- and linezolid-treated groups (P < 0.05) at 6 and 12 h after the inoculation of Enterococcus. The level of neutrophil chemoattractants KC in the peritoneal fluid at 12 h after enterococcal inoculation was significantly decreased in the DAP plus ampicillin-treated group (P < 0.05). In addition DAP showed the inhibitory effect of enterococcal biofilm formation dose-dependently by a microtiter biofilm assay. These results indicate that DAP, particularly with β-lactams, is a possible alternative agent to treat severe enterococcal infection such as peritonitis.

Clinical characteristics and risk factors of enterococcal infections in Nagasaki, Japan: a retrospective study

BACKGROUND

Enterococcus spp. are particularly important etiological agents of nosocomial infections. However, the clinical characteristics of and risk factors for enterococcal infections in clinical settings are poorly understood.

METHODS

The sample included patients with Enterococcus spp. infections detected from clinical samples at Nagasaki University Hospital between 2010 and 2011 and patients with enterococcal colonization (control patients). In this retrospective study, the risk factors for enterococcal infections were analyzed by comparing infected and control patients via multivariate logistic regression.

RESULTS

A total of 182 infected (mean age, 64.6 ± 18.2 years; 114 men) and 358 control patients (patients with enterococcal colonization) (mean age, 61.6 ± 22.4 years; 183 men) were included. Enterococcal infections were classified as intraperitoneal (n = 87), urinary tract (n = 28), or bloodstream (n = 20) infections. Cancer and hematological malignancies were the most common comorbidities in enterococcal infections. Carbapenem and vancomycin were administered to 43.8 % and 57.9 % of patients infected with Enterococcus faecalis and Enterococcus faecium, respectively. No vancomycin-resistant enterococci were isolated. Multivariate analysis identified abdominal surgery (odds ratio [OR], 2.233; 95 % confidence interval [CI], 1.529-3.261; p ≤ 0.001), structural abnormalities of the urinary tract (OR, 2.086; 95 % CI, 1.088-4.000; p = 0.027), male sex (OR, 1.504; 95 % CI, 1.032-2.190; p = 0.033), and hypoalbuminemia (OR, 0.731; 95 % CI, 0.555-0.963; p = 0.026) as independent risk factors for enterococcal infections. Multivariate analysis showed abdominal surgery (OR, 2.263; 95 % CI, 1.464-3.498; p ≤ 0.001), structural abnormalities of the urinary tract (OR, 2.634; 95 % CI, 1.194-5.362; p = 0.008), and hypoalbuminemia (OR, 0.668; 95 % CI, 0.490-0.911; p = 0.011) were independent risk factors for E. faecalis infection. Finally, immunosuppressive agent use (OR, 3.837; 95 % CI, 1.397-10.541; p = 0.009) and in situ device use (OR, 3.807; 95 % CI, 1.180-12.276; p = 0.025) were independent risk factors for E. faecium infection.

CONCLUSIONS

These findings might inform early initiation of antimicrobial agents to improve clinical success.

Macrolides Promote CCL2-Mediated Macrophage Recruitment and Clearance of Nasopharyngeal Pneumococcal Colonization in Mice

BACKGROUND

Streptococcus pneumoniae (pneumococcus) colonizes mucosal surfaces of the upper respiratory tract (URT), resulting in invasive disease. Macrolides are known for their immunomodulatory effects. We investigated the potency of macrolides to reduce pneumococcal colonization by activating host innate immunity.

METHODS

The kinetics of colonization, cellular response, and inflammatory cytokine levels in the URT were assessed after nasal inoculation of pneumococci. EM900 (a novel 12-membered nonantibiotic macrolide with an immunomodulatory effect) was orally administered throughout the experiment. Survival was evaluated for 10 days. Macrolide-mediated CCL2 production from peritoneal macrophages was determined by enzyme-linked immuosorbent assay. The cell-signaling pathway was analyzed by means of Western blotting and gene silencing assays.

RESULTS

Streptococcus pneumoniae was significantly reduced from EM900-treated mice 14 days after pneumococcal inoculation. Macrophage recruitment and Ccl2 messenger RNA expression were promoted. CCL2 production from peritoneal macrophages was significantly induced by macrolides and was dependent on NF-κB phosphorylation through the myeloid differentiation primary-response gene 88- or TIR domain-containing adapter-inducing interferon-β-mediated pathway. Mortality of mice with invasive pneumococcal disease was improved by pretreatment with EM900.

CONCLUSIONS

Macrolides may inhibit invasive pneumococcal infections by accelerating the clearance of pneumococcal nasopharyngeal colonization via promotion of macrophage-mediated innate immunity.

[Two cases of emphysematous urinary tract infections successfully treated with conservative management]

Emphysematous urinary tract infection is a rare, fulminant complication that is characterized by the presence of gas in the pelvicaliceal system, renal parenchyma, perinephric tissues and retroperitoneum. Surgical resection is usually regarded as the treatment of choice, however several studies have shown the safety and efficacy of conservative management under the correct diagnosis and appropriate antibiotic administration. We herein report on two cases of emphysematous urinary tract infection, pyelonephritis and cystitis infected with ESBL-producing Eschrerichia coli, complicated with diabetic mellitus which were successfully treated with conservative treatment.

The effect of intravenous peramivir, compared with oral oseltamivir, on the outcome of post-influenza pneumococcal pneumonia in mice

BACKGROUND

Pneumococcal pneumonia often occurs secondary to influenza infection and accounts for a large proportion of the morbidity and mortality associated with seasonal and pandemic influenza outbreaks. Peramivir is a novel, intravenous neuraminidase inhibitor that exhibits potent antiviral activity against influenza A and B viruses. We investigated the efficacy of peramivir for modulating the severity of secondary pneumococcal pneumonia.

METHODS

CBA/JNCrlj mice, infected with influenza virus and superinfected with Streptococcus pneumoniae, were treated with either intravenous peramivir (single or multiple doses of 60 mg/kg/day) or oral oseltamivir at doses of 10 or 40 mg/kg/day in divided doses. The survival rate, viable bacterial count and virus titre in the lungs, as well as cytokine/chemokine concentration and histopathological findings were compared between both groups.

RESULTS

The median duration of survival of coinfected mice was significantly prolonged by treatment with multiple doses of peramivir, relative to mice treated with oseltamivir at either dose. Viable bacterial counts and virus titres in the lungs were significantly reduced by intravenous peramivir treatment compared with no treatment or oral oseltamivir treatment. The production of inflammatory cytokines/chemokines was also significantly suppressed by multiple dosing of peramivir compared with oseltamivir. Increased survival appeared to be mediated by decreased inflammation, manifested as lower levels of inflammatory cells and proinflammatory cytokines in the lungs and less severe histopathological findings. The lungs of mice treated with multiple doses of peramivir showed mild inflammatory changes compared to oseltamivir.

CONCLUSIONS

This study demonstrated that a multiple-dose regimen of intravenous peramivir was more efficacious than a single peramivir dose or multiple doses of oseltamivir for improving outcomes in pneumococcal pneumonia following influenza virus infection in mice.

Differential effects of urinary and recombinant chorionic gonadotropin on oxidative stress responses in decidualizing human endometrial stromal cells

Human chorionic gonadotropin (hCG) is one of the earliest signals secreted by the implanting embryo. In addition to its well-known luteotropic function in early pregnancy, hCG also acts directly on decidualizing endometrium. Recently, we demonstrated that recombinant hCG (rhCG) prevented apoptosis in decidualizing human endometrial stromal cells (HESCs) exposed to oxidative stress. Two hCG preparations are widely used clinically: rhCG, produced by recombinant DNA technology, and urinay hCG (uhCG), extracted from urine of post-menopausal women. However, an analysis of the direct effects of rhCG and uhCG on the decidual phenotype of HESCs has not yet been done. In this study, we investigated the effects of uhCG and rhCG on the morphological and functional profiles of decidualizing HESCs. We demonstrate that neither rhCG nor uhCG alter the morphological appearance of the decidual HESC cultures, although rhCG but not uhCG attenuated prolactin expression, a major decidual marker protein. Moreover, rhCG, but not uhCG, protected decidualizing HESCs from oxidative cell death, mediated at least in part by two major mechanisms. First, rhCG, but not uhCG, enhances the expression of manganese superoxide dismutase, a cardinal enzyme in the cellular defense against oxidative damage. Second, rhCG signaling selectively limits activation of the apoptotic machinery in decidualizing HESCs by enhancing Bcl-2 expression whereas uhCG induces the expression of Fas ligand. Our results suggest that rhCG might be a preferable agent to protect the maternal decidua against oxidative damage in pregnancy, especially at the time of implantation and beyond.

[A retrospective study of carboplatin and weekly paclitaxel combination chemotherapy for elderly patients with advanced non-small cell lung cancer]

OBJECTIVE

To perform a retrospective analysis of carboplatin (CBDCA) and weekly paclitaxel (PTX) combination chemotherapy for elderly patients with unresectable non-small cell lung cancer (NSCLC) in order to evaluate both treatment efficacy and toxicity.

SUBJECTS

48 patients aged more than 70 years with non-resectable NSCLC who received CBDCA+weekly PTX from January 2001 to March 2008.

RESULTS

The median age of the patients (32 male, 16 female) was 74 years. Patients received 1-6 courses of this chemotherapy (median 4 courses). The overall response rate, time to progression, median survival time and 1-year survival rate was 51%, 183 days, 411 days and 52%, respectively. With regard to toxicity, grade 3-4 neutropenia was observed in 38% of patients and anemia in 25% of the patients, and 29% of the patients had grade 2 and above periferal nerve disorder.

CONCLUSION

This regimen showed a good response and was safe for elderly patients with advanced NSCLC, but a high incidence of neuropathy was observed.

[Retrospective analysis of amrubicin hydrochloride monotherapy in patients with previously treated small-cell lung cancer]

We retrospectively investigated amrubicin hydrochloride(AMR)monotherapy as second or thirdline chemotherapy for small-cell lung cancer(SCLC)and assessed its efficacy and safety. AMR was intravenously administered at 25-45mg/m2 for 3 consecutive days every 3-4 weeks. Fifty-three patients were enrolled. Response rates and median survival times were as follows: total cases, 32% and 7. 4 months; sensitive relapse cases, 64% and 16. 4 months; refractory relapse cases, 27% and 5. 9 months. Neutropenia was major toxicity(Grade 3 or 4 was observed in 72% of the subjects), whereas nonhematologic toxicities were mild. Treatment with AMR appeared effective in SCLC patients previously treated with chemotherapy. On the other hand, it must be used carefully because of its relatively severe hematologic toxicities.

[Clinical investigation of weekly Carboplatin and Paclitaxel with concurrent radiation therapy for locally advanced non-small cell lung cancer]

PURPOSE

The aim of this study was to evaluate retrospectively chemotherapy of weekly carboplatin and paclitaxel with concurrent radiation therapy for patients with locally advanced non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Between January 2000 and March 2008, 38 patients were treated by chemotherapy with carboplatin and paclitaxel once a week, repeated for 6 weeks, with thoracic radiation therapy of 1 or 2 times a day on weekdays. After concurrent chemoradiotherapy, we planned consolidation chemotherapy of carboplatin(AUC 5-6)and weekly paclitaxel(70- 80 mg/m(2)) on day 1, 8 and 15, when possible.

RESULTS

The enrolled patients were 31 men and 7 women, with the median age of 59 years (39-76 years), stage III A/III B: 10/28, Ad/Sq/AdSq/Un: 17/17/2/2. The response rate of this chemoradiotherapy was 78. 9%. The median survival time and time to progression were 24. 7 months and 8. 1 months, respectively. Grade 3 or 4 hematological toxicities during concomitant chemoradiotherapy were leukocytopenia(5. 2%)and neutropenia(5. 2%). Grade 3 or 4 non-hematological toxicities were esophagitis(2. 6%)and pneumonitis (5. 2%). There was a therapy-associated death by radiation pneumonitis.

CONCLUSION

Carboplatin and paclitaxel with concurrent radiation therapy for a patient with stage III NSCLC showed a good response with relatively mild side effects. We reached the conclusion that concurrent chemoradiotherapy would be a useful choice for locally advanced non-small cell lung cancer on the practical clinic.

[Two cases of lung injury due to inhalation of waterproofing spray--with special reference to pulmonary function disorder]

CASE 1: A 57-year-old man experienced severe dyspnea 24 hours after inhalation of waterproofing spray. Computed tomography (CT) revealed diffuse ground glass opacities in bilateral lungs. Pulmonary function tests showed mixed ventilatory disturbance with a low expiratory flow rate near the end of forced expiration and a normal diffusing capacity with normal functional residual capasity. The pulmonary function disorder was quickly improved by steroid therapy. CASE 2: A 59-year-old man smoked after inhaling waterproofing spray and soon developed dyspnea. The findings of CT were similar to those of case 1. His pulmonary function test revealed restrictive ventilatory disturbance and normal pulmonary diffusing capacity with low functional residual capacity. These findings improved without steroid treatment. However, it took more time for the pulmonary function to recover. There was probably specific inflammation around bronchioles, and the inflammation might have spread to the alveolar region in such cases with severe pulmonary function disorder. Steroid treatment seems to be useful to improve both the pulmonary function disorder and the clinical feature due to inhalation of waterproofing spray.

[A foreigner case of pulmonary tuberculosis with patient's and doctor's delay]

A 80-year-old man who came from Korea a few days previously, had a high fever and dyspnea. Chest radiography and computed tomography showed various shadow suggesting tumors, small nodules and reticular shadows with effusion. We made a clinical diagnosis of lung cancer with pneumonia. Finally, however, the culture of bronchial lavage fluid and transbronchial biopsy revealed tuberculosis. It was obvious that there were delaying factors such as the patient's social and economical situation as well as the diagnostic difficulty concerning the chest image findings. Whenever we find a abnormal shadow on chest images, we should consider mycobacterium infection in the differential diagnosis disease.

Hepatocyte growth factor in gingival crevicular fluid and the distribution of hepatocyte growth factor-activator in gingival tissue from adult periodontitis

Hepatocyte growth factor (HGF), also known as scatter factor, is a broad-spectrum and multifunctional cytokine required for the development, growth and regeneration of various organs and tissues. The expression of HGF in human gingival fibroblasts is induced by inflammatory cytokines such as interleukin 1. Thus, although it is possible that content of HGF in gingival crevicular fluid (GCF) in periodontitis is increased, this has not so far been reported because the volume of GCF is too small to determine HGF by the available enzyme-linked immunosorbent assay (ELISA). A recently developed, highly sensitive ELISA for HGF, with a detection limit of 1 pg/ml sample, has now enabled HGF to be measured in GCF.The mean HGF content in GCF from sites with clinically healthy gingiva, defined by the absence of overt signs of gingival inflammation and a probing depth (PD) <3 mm, was 1.7 ng/ml, and that of periodontitis, defined by obvious alveolar bone loss detected by radiographic examination and a PD> or =3 mm, was 3.23 ng/ml. Although treating the periodontitis did not significantly decrease the HGF concentration despite significantly improved clinical scores such as PD and Gingival Index, the total amount of HGF in GCF did decrease significantly after treatment. HGF was expressed by gingival fibroblasts and inflammatory cells as determined by in situ hybridization. HGF-activator (HGFA), which converts inactive pro-HGF to active mature HGF, was detected in gingival epithelial cells by immunostaining. The expression of HGFA was also confirmed in gingival tissue by reverse transcription-polymerase chain reaction (RT-PCR). These findings indicate that HGF is synthesized and activated in gingiva that is clinically healthy or associated with periodontitis.

Surface curvatures of trabecular bone microarchitecture

Microstructure of trabecular bone has been examined with a particular emphasis on surface curvatures in two-phase (trabecular and intertrabecular space- i.e., marrow space) structures. Three trabecular bone samples, quantified as "plate-like," "rod-like," and a mixture of these two structural elements according to the structure model index (SMI), were subjected to analysis based on (differential) geometry. A correspondence between the SMI and the mean curvature was found. A method to measure surface curvatures is proposed. The gaussian curvatures averaged over the surfaces for the three analyzed bone structures were all found to be negative, demonstrating their surfaces to be, on average, hyperbolic. In addition, the Euler-Poincaré characteristics and the genus, both characterizing topological features of bone connectivity, were estimated from integral gaussian curvature (Gauss-Bonnet theorem). The three bone microstructures were found to be topologically analogous to spheres with one to three handles.

Interfacial and topological measurements of bicontinuous polymer morphologies

Bicontinuous morphologies are ubiquitous in nature and occur at various length scales. Topological features of two such morphologies arising in an ordered block copolymer at equilibrium and a polymer blend during spinodal decomposition are measured from three-dimensional images. Interfacial curvature, coordination number, and interjunction distance distributions exhibit remarkable similarity in these systems, despite vastly different length scales. A channel coordination of 3 is dominant in both morphologies, and topological measurements such as the Euler-Poincaré characteristic and genus are reported.

Bilirubin overload modulates bile canalicular membrane fluidity in rats: association with disproportionate reduction of biliary lipid secretion

We recently demonstrated that several organic anions cause dissociation of biliary lipid secretion from that of bile acids; namely, the "uncoupling phenomenon," in association with changes in the phospholipid molecular species in the canalicular membrane lipid bilayer. Because of the uncoupling phenomenon, transcytotic vesicles are retained inside cells, resulting in the accumulation of substances normally excreted in the bile. In the present study, bilirubin ditaurate (BDT; synthetic bilirubin) was used to investigate the effect of bilirubin overload on biliary lipid secretion and the lipid composition of hepatic subcellular fractions, as well as canalicular membrane packing density and fluidity. Male Sprague-Dawley rats underwent cannulation of the bile duct and femoral vein. Sodium taurocholate was infused intravenously at 100 nmol/min per 100 g body weight. Then BDT (50 nmol/min per 100 g body weight) was infused concomitantly, followed by periodic bile collection for analysis of lipids. Bile acid secretion was not significantly affected by the infusion of BDT. In contrast, the secretion of cholesterol and phospholipids was decreased by 56.7% and 49.2%, respectively, compared with control. The phosphatidylcholine hydrophobicity of canalicular membrane vesicles, estimated by the molar ratio of saturated to unsaturated fatty acids (S/U ratio) was decreased, but not significantly by BDT infusion. With BDT infusions, the biliary cholesterol/phospholipid (C/P) ratio was increased by 19%; canalicular membrane vesicle fluidity was decreased by 5.8%, whereas P-glycoprotein expression was unchanged. As P-glycoprotein expression was not altered, our findings suggested that the reduced canalicular membrane vesicle fluidity was a crucial regulator of canalicular membrane transporter function.

Factors affecting gallstone recurrence after successful extracorporeal shock wave lithotripsy

Ninety-six patients treated successively for symptomatic cholelithiasis with extracorporeal shock wave lithotripsy (ESWL) and oral bile acid therapy consisting of ursodeoxycholic acid in daily dosages of 600 mg were prospectively followed for gallstone recurrence for a median of 13 months. Ultrasonography was performed to detect stone recurrence at 3, 6, and 12 months, and then yearly after the termination of therapy. Recurrent stones were found in 17 patients (18%). The cumulative probability of gallstone recurrence was 15.8% at 12 months, 26.1% at 24 months, and 30.7% at 36 months. The probability of stone recurrence over the entire period of observation was not dependent on stone number, whereas the median interval to detection of recurrence was significantly shorter in the patients with multiple stones (2 months) than in those with solitary stones (8 months) (p < 0.05). The rate of impaired gallbladder contractility was higher in patients with recurrence (8/15, 53.3%) when compared with those with no recurrence (15/72, 20.8%) (p < 0.01). Neither age, gender, or stone characteristics predicted stone recurrence. Only one patient with a recurrence reported biliary pain. Of the 15 patients with recurrent stones who opted for further nonsurgical treatment, complete stone disappearance was achieved in 10. Impaired gallbladder function may predict gallstone recurrence after ESWL.

Role of phospholipase A2 in cholesterol gallstone formation is associated with biliary phospholipid species selection at the site of hepatic excretion: indirect evidence

Phospholipase A2 plays a role in cholesterol gallstone development by hydrolyzing bile phospholipids into lysolecithin and free fatty acids. Lysolecithin and polyunsaturated free fatty acids are known to stimulate the synthesis and/or secretion of gallbladder mucin via a prostanoid pathway, leading to enhancing cholesterol crystal nucleation and growth, and therefore, the action of phospholipase A2 is associated, in part, with bile phospholipid fatty acid. To clarify this hypothesis, we evaluated the effect on bile lipid metastability in vitro of replacing phospholipids with lysolecithin and various free fatty acids. Supersaturated model biles were created with an identical composition (cholesterol saturation index, 1.8; egg yolk lecithin, 34 mM; taurocholate, 120 mM; cholesterol, 25 mM) except for 5%, 10%, or 20% replacement of egg yolk lecithin with a combination of palmitoyl-lysolecithin and a free fatty acid (palmitate, stearate, oleate, linoleate, or arachidonate), followed by time-sequentially monitoring of vesicles and cholesterol crystals using spectrophotometer and video-enhanced differential contrast microscopy. Replacement with hydrophilic fatty acids (linoleate and arachidonate) reduced vesicle formation and promoted cholesterol crystallization, whereas an enhanced cholesterol-holding capacity was evident after replacement with hydrophobic fatty acids (palmitate and stearate). These results indicate that the effect of phospholipase A2 on bile lithogenecity is modulated by the fatty acid species in bile phospholipids, and therefore, that the role of phospholipase A2 in cholesterol gallstone formation is dependent, in part, on biliary phospholipid species selection at the site of hepatic excretion.

The blood supply of the lateral epiphyseal arteries in Perthes' disease

We performed superselective angiography in 28 hips in 25 patients with Perthes' disease in order to study the blood supply of the lateral epiphyseal arteries (LEAs). Interruption of the LEAs at their origin was observed in 19 hips (68%). Revascularisation in the form of numerous small arteries was seen in ten out of 11 hips in the initial stage of Perthes' disease, in seven of eight in the fragmentation stage and in five of nine in the healing stage. Penetration of mature arteries into the depths of the epiphysis was seen in four of nine hips in the healing stage. Vascular penetration was absent in the weight-bearing portion of the femoral head below the acetabular roof. Interruption of the posterior column artery was seen where it passed through the capsule in seven hips when they lay either in internal rotation or in abduction with internal rotation. We suggest that in Perthes' disease the blood supply of the LEAs is impaired at their origin and that revascularisation occurs from this site by ingrowth of small vessels into the femoral epiphysis. This process may be the result of recurrent ischaemic episodes.

The blood supply of the lateral epiphyseal arteries in Perthes’ disease

We performed superselective angiography in 28 hips in 25 patients with Perthes’ disease in order to study the blood supply of the lateral epiphyseal arteries (LEAs). Interruption of the LEAs at their origin was observed in 19 hips (68%). Revascularisation in the form of numerous small arteries was seen in ten out of 11 hips in the initial stage of Perthes’ disease, in seven of eight in the fragmentation stage and in five of nine in the healing stage. Penetration of mature arteries into the depths of the epiphysis was seen in four of nine hips in the healing stage. Vascular penetration was absent in the weight-bearing portion of the femoral head below the acetabular roof. Interruption of the posterior column artery was seen where it passed through the capsule in seven hips when they lay either in internal rotation or in abduction with internal rotation.

We suggest that in Perthes’ disease the blood supply of the LEAs is impaired at their origin and that revascularisation occurs from this site by ingrowth of small vessels into the femoral epiphysis. This process may be the result of recurrent ischaemic episodes.

Posterior rotational osteotomy for the treatment of femoral head osteonecrosis

Posterior rotational osteotomy in 46 hips of 39 patients with femoral head osteonecrosis was reviewed radiographically and clinically after 2-12 years of follow-up (mean 5 years). The age of the patients at the time of surgery ranged from 18 to 60 years, with a mean of 35 years. There were 18 women and 21 men. The cause of the osteonecrosis was steroid administration in 14, alcohol abuse in 5, trauma in 16, and no apparent risk factor in 4. According to the Ficat staging system, 2 hips were stage II, 30 hips III, and 14 hips stage IV. All hips had an extensive lesion. Forty-one hips showed less than 1/3 noncollapsed posterior living area, which was a contraindication for traditional anterior rotational osteotomy. The posterior rotational angle was 60-180 deg with an mean of 127 deg. Recollapse of the final follow-up anteroposterior radiograph was prevented in 36 hips (78%). Progressive joint space narrowing was found in 12 hips (26%). Of these hips, 9 suffered recollapse, while the remaining 3 hips did not. Clinically, 32 hips (70%) showed excellent or good results (both hips in stage II, 23 of 30 hips in stage III, 7 of 14 hips in stage IV. A fair or poor result was seen in 14 hips (30%)). These results suggest that posterior rotational osteotomy is effective in delaying the progression of degeneration for large necrotic lesions, especially in young patients. Extent of rotation is limited to 150 deg because of limitations of bone quality. The indications should be refined further, and longer term follow-up is necessary.

Involvement of a cis-acting element in the suppression of carbamoyl phosphate synthetase I gene expression in the liver of carnitine-deficient mice

The expression of carbamoyl phosphate synthetase I (CPS) gene is suppressed in the liver of carnitine-deficient juvenile visceral steatosis (JVS) mice at weaning and under starvation at adult age. To clarify the suppression mechanism, we produced CPSL transgenic JVS mice carrying a transgene composed of the chloramphenicol acetyltransferase (CAT) gene with the upstream region (-12 kb to +138) of the rat CPS gene and CPSE transgenic JVS mice carrying a transgene composed of the luciferase gene with minimal promoter (299 bp from -161 to +138) and enhancer (469 bp around -6.3 kb) fragments of the rat gene. The expression of the CAT gene as well as the endogenous CPS was suppressed in CPSL transgenic JVS mice, but luciferase gene expression was not suppressed in CPSE transgenic JVS mice. We isolated the 5'-upstream region of the mouse CPS gene and identified an activator protein-1 (AP-1) site downstream of the minimum enhancer region of both rat and mouse CPS genes. In conjunction with the 313-bp mouse promoter region, the 714-bp mouse enhancer fragment conferred a cell-type-dependent hormone responsiveness. In rat primary cultured hepatocytes, the addition of oleic acid suppressed reporter gene expression induced by dexamethasone in the construct containing the enhancer fragment of 714 bp with the AP-1 site, but not in its AP-1 site mutants or in 519 bp without the AP-1 site. These results strongly suggest that direct protein-protein interaction between AP-1 and glucocorticoid receptor is not involved in the suppression of the CPS gene in JVS mice and that the AP-1 element is the cis-element which is responsible for the suppression.

Effects of rat fetuin on stimulation of bone resorption in the presence of parathyroid hormone

Rat fetuin, which is the rat counterpart of human alpha 2-HS glycoprotein and bovine fetuin, is only detectable in calcified tissues such as bone matrices and dentin, and bone cells such as osteoblasts and osteocytes immunohistochemically. The effect of this protein on bone resorption was examined to study its physiological role in bone metabolism. Rat fetuin increased bone resorption in the presence of low concentrations of parathyroid hormone (PTH), but it had no activity on bone resorption without PTH. The increase in bone resorption by PTH and PTH plus rat fetuin was inhibited by the addition of chymostatin, an inhibitor for cathepsin L. Moreover, we found that when type I collagen from rat was preincubated with rat fetuin, the digestion of rat type I collagen by cathepsin L was increased. These findings suggest that rat fetuin present in bone matrix is important in bone resorption.

Effects of bilirubin ditaurate on biliary secretion of proteins and lipids: influence on the hepatic vesicle transport system

BACKGROUND

Several organic anions cause dissociation of biliary lipid secretion from bile acid secretion (uncoupling). As bile lipids originate from liver microsomes and are transported by carrier proteins and/or transcytotic vesicles, such a reduction of biliary lipid secretion may lead to cytosolic accumulation of vesicles. This study investigated whether bilirubin conjugate, a physiologically important organic anion, caused uncoupling and whether hepatic retention of compounds carried by transcytotic vesicles occurred subsequently, using bilirubin ditaurate, a synthetic commercially available compound.

METHODS

Cannulation of the bile duct and femoral vein was done in male Sprague-Dawley rats. Sodium taurocholate was infused intravenously at a constant rate of 100 nmol/min per 100 g bodyweight. Bilirubin ditaurate (50 nmol/min per 100 g bodyweight) was infused concomitantly, followed by periodical bile collection for analysis of lipids, total protein and immunoglobulin A.

RESULTS

Biliary bile acid secretion was not changed significantly by infusion of bilirubin ditaurate. In contrast, the secretion of cholesterol, phospholipids and immunoglobulin A was decreased by 57.3, 48.7 and 44.8%, respectively. The biliary cholesterol:phospholipid ratio was increased by 19%. Uncoupling was caused by bilirubin ditaurate and biliary immunoglobulin A secretion was decreased.

CONCLUSIONS

As immunoglobulin A is a major protein carried by intrahepatic transcytotic vesicles, uncoupling may involve impairment of intrahepatic vesicular transport. Also, a reduction of immunoglobulin A secretion into bile by organic anion-induced uncoupling may weaken biliary immunity.