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.

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.

[Role of medium-sized independent laboratories in control of healthcare-associated infection]

In 2006, the Ministry of Health and Welfare revised the regulations regarding the Medical Service Law. The amendments stipulate that all healthcare institutions are required to implement infection control programs. However, small hospitals and clinics have no clinical microbiology laboratories, whereas medium-sized hospitals have few medical technologists and the outsourcing of microbiology tests to independent laboratories is common. The decreasing number of laboratories and recent outsourcing tendency reflect the increasing commercialization, and, with it, the escalating number of commercially operating chains. Each independent laboratory is responsible for supporting activities related to the surveillance, control, and prevention of healthcare-associated infections in the associated small and medium-sized hospitals. The people responsible for infection control in these hospitals usually do not have a background in microbiology. The evaluation of communication between independent laboratory staff and hospital personnel, and rapid turnaround time of microbiology laboratory test reports are important elements ensuring the quality of independent laboratory work. With the pressures of financial constraints in the Japanese medical insurance system, the development of a cost-effective and practical protocol for quality assurance is a real dilemma.

[Contamination of flexible fiberoptic bronchoscopes with Mycobacterium chelonae linked to an automated endoscope disinfection machine--on the relationship between the presence of the organism in the intestinal tract and contamination of disinfection machine, and a case of gallbladder and bile duct infection with M. chelonae]

In 1993, thirteen strains (8.7%) of M. chelonae were isolated from bronchoalveolar lavage fluid (BALF) obtained by bronchoscopy of 150 patients in Tachikawa-sogo (T) hospital, where the same automated disinfection machine was commonly used for cleaning, sterilization and disinfection of fiberbronchoscope and fibercolonoscope except 3 bronchoscopes disinfected by gas sterilization. Since January 1994, manual cleaning and sterilization has been applied for bronchoscope, and thereafter no strain of M. chelonae was isolated from BALF of 55 patients in the T hospital. While only one strain (3%) of M. chelonae was isolated from BALF of 33 patients in Ota (O) hospital, but many strains of M. chelonae were isolated from intestinal fluid obtained by fibercolonoscopy of the patients. Manual method of cleaning and disinfection was performed for both bronchoscopes and colonoscopes in the O hospital from the beginning. Based on these results, it was suggested that M. chelonae are commonly present in the colon (intestine) of normal persons. Thus colonoendscope may be often contaminated with the organism and subsequently the automated disinfecting machine may also be contaminated with the organism which is resist and against usual disinfection procedure, and resulted in bronchoscope contamination. If the presence of M. chelonae in intestinal tract is not rare, bile duct may be naturally infected with the organism. A case of cholecystitis and cholangitis caused by M. chelonae, which has not been reported previously, was found in the T hospital.

The functional significance of the second extracellular loop of thyrotropin receptor in thyrotropin- and thyroid stimulating antibody-dependent signal transduction

In order to determine the functional significance of the extracellular loop of human thyrotropin receptor (hTSHR), two peptides composed of eight amino acids were inserted into hTSHR by ligating synthetic oligonucleotides into +1811 NCol site of hTSHR cDNA. Mutant hTSHR cDNAs which encode a hydrophobic peptide (ATVLVVPM) and a hydrophilic peptide (GTTRTVAM) between +572 Met and +573 Asp were transfected into Chinese hamster ovary (CHO) cells to develop F-cell lines and R-cell lines, respectively. Of the resulting cloned cell lines, F-29 and R-9 were shown to express mutant hTSHs at the protein level by Western blotting and at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR). We show that neither thyrotropin (TSH) nor IgGs from patients with Graves' disease stimulated cAMP production by F-29 and R-9 cells. 125I-TSH binding study revealed that F-29 and R-9 cells do not bind TSH. Our data demonstrate that the mutations impaired TSH-binding and incapacitated the cells from responding to TSH. The evidence suggests that the second extracellular loop of hTSHR has an important role in TSH and thyroid stimulating antibody (TSAb)-dependent signal transduction.

Thyrotrophin-dependent desensitization by Chinese hamster ovary cells that express the recombinant human thyrotrophin receptor

To determine whether thyrotrophin (TSH)-induced desensitization requires a thyroid-specific factor(s), the human TSH (hTSH) receptor was expressed in Chinese hamster ovary cells. The first incubation of the cells with TSH decreased the subsequent response of adenosine 3',5'-cyclic monophosphate to freshly added TSH in the second incubation. This homologous desensitization was observed as early as after 3 h of the first incubation. The lowest dose of TSH that elicited desensitization was 0.1 nmol/l. The desensitization was not overcome by adding higher doses of TSH in the second incubation. A 125I-labelled TSH-binding study revealed a decrease in the number of high-affinity binding sites but not in that of low-affinity binding sites. The data suggest that TSH-induced desensitization in hTSH receptor-transfected cells is caused, at least in part, by a decrease in the number of TSH receptors on the cell surface. The evidence demonstrates, contrary to an earlier report, that a thyroid-specific factor(s) is not required for hTSH receptor desensitization.

Detection of verocytotoxin from stool and serological testing of patients with diarrhea caused by Escherichia coli O157 : H7

The detection of verocytotoxin (VT) in stool and measurement of antibodies against VT and three antigens (unheated-antigen, LPS, and flagellin) of Escherichia coli O157 : H7 in the serum of patients with diarrhea were examined. Five of 14 inpatients during an outbreak had fecal VT2 in stool taken within 5 days of onset to hospitalization. Among these 5, 3 of them also had fecal VT-producing E. coli (VTEC) serotype O157 : H7, whereas the other 2 did not. In the passive hemagglutination (PHA) test with formalinized sheep red blood cells sensitized with three VTEC O157 : H7 antigens, 49 (74.2%) of 66 outbreak patients and 3 of 3 sporadic cases had antibodies against both or one of unheated-antigen and LPS of E. coli O157, but none had antibody against flagellin. In addition, anti-VT2 antibody was demonstrated in serum samples from 15 (94%) of 16 inpatients and 2 (4%) of 50 outpatients in an outbreak by a VT-enzyme-linked immunosorbent assay (VT-ELISA). These results showed that serological assay particularly for antibodies against VT and unheated-antigen or LPS of VTEC O157 may provide a useful tool for diagnosis of infection with VTEC O157.

Single subunit structure of the human thyrotropin receptor

We have produced rabbit antibody against a synthetic peptide corresponding to N-terminal region of the extracellular domain of human thyrotropin receptor (hTSH-R) (N peptide, aminoacid residues 29-57). Western blot analysis revealed that N-peptide antibody recognized recombinant hTSH-R stably expressing in CHO-K1 cells as a mol. wt. about 104 kDa regardless in the presence or absence of disulfide-reducing agent. The band was not detected in untransfected CHO-K1 cells and no band was also stained by the antibody absorbed with N-peptide. In a reducing condition, the antibody also bound the rat receptor from FRTL5 cells as the same molecular size (104 kDa). These results clearly indicate that TSH-R is composed of a single subunit and that two subunit model for the TSH-R may reflect artifactual proteolytic cleavage of the receptor during membrane preparation.

Heterogeneous responses of recombinant human thyrotropin receptor to immunoglobulins from patients with Graves' disease

Non-thyroid mammalian cells, CHO-K1 cells, stably expressing human thyrotropin receptor (CHO-TSH-R cells) were used for the assay of thyroid stimulating antibody (TSAb) activities of IgGs from 24 patients with Graves' disease and we compared them with the values obtained in porcine thyroid cells. A significant positive correlation was observed between the results given by CHO-TSH-R cells (hTSAb) and porcine thyrocytes (pTSAb) (r = 0.94, p less than 0.001). However, we found that hTSAb values of IgGs from 5 patients were extremely different from their hTSAb values. Four out of these 5 IgGs showed strong pTSAb activity but exhibited a weak or negative hTSAb activity. Conversely, one out of 5 autoantibodies was very strong for hTSAb but its pTSAb was low. These heterogeneous responses of recombinant hTSH-R to Graves' IgGs suggest that there exist different types of TSAb and also that the epitope(s) for TSAb may be different from case to case.

[Studies on epidemiology of nontuberculous mycobacteriosis--on the regional difference of the incidence of pulmonary diseases due to M. kansasii and M. avium complex in Tokyo area]

On 397 patients with pulmonary disease due to nontuberculous mycobacteria (NTM) [102 due to M. kansasii (MK) and 295 due to M. avium complex (MAC)] observed at National Tokyo Chest Hospital, 191 patients with pulmonary disease (59 due to MK and 132 due to MAC) observed at Fukujuji Hospital of Antituberculosis Association and 257 patients from whose sputum MK (36) or MAC (221) were isolated in Byotai-Seiri Clinical Laboratory, the distribution of these patients by domicile in Tokyo area was analysed. The percentage of patients with MK disease among the whole patients with MK disease and MAC disease (MK ratio) in each community area was investigated. MK ratio was 30.9% in the 23 wards and 16.4% in Tama section of Tokyo in the patients observed at National Tokyo Chest Hospital. It was 37.0% in the 23 wards and 32.1% in Tama section in the patients observed at Fukujuji Hospital and was 17.7% in the 23 wards and 8.1% in Tama section in the patients observed at Byotai-Seiri Clinical Laboratory. MK ratio in Tokyo was considerably higher in the 23 wards that were densely populated industrial and commercial areas than in Tama section, a comparatively sparsely populated suburb. MK ratio in patients of Ota Hospital located in the 23 wards was higher (36.4%) than that of Tachikawa-Sogo Hospital located in Tama area (10.0%). Regional differences in MK ratio were remarkable in Tokyo area. A high MK ratio appeared to correlate with a high incidence rate of tuberculosis. From the results mentioned above, it was suggested that M.K. disease may be transmitted from person to person.

[123I-iodoamphetamine single photon emission computed tomography in three patients with amyotrophic lateral sclerosis]

We examined the 123I-iodoamphetamine SPECT for 3 patients with ALS, who were clinically diagnosed. Patient 1 was a 31-years-old man, who had bilateral muscle weakness of his upper extremities, and spasticity in lower extremities. Patient 2 was a 51-years-old woman, who had marked weakness of her upper extremities and bulbar sign. Patient 3 was a 68-years-old man, who had severe degree of marked weakness of his upper extremities and mild bulbar signs. Cerebral cognitive function were all normal in three patients. Computed tomographic and magnetic resonance imagings showed moderate degree of cortical atrophy in patient 1, but no abnormalities in patients 2 and 3. In 123I-IMP SPECT, however, hypoperfusion were recognized on the bilateral fronto-parietal border zone areas in these three patients with ALS. It was suggested that patients with ALS showed varying degrees of impaired perfusion in the fronto-parietal border zone areas in spite of normal cognitive functions.

[Basic and clinical studies on the effect of cefmetazole on infection in gyneco-obstetrics]

Cefmetazole (CMZ) was administered to 102 infectious cases in the gynecoobstetric patients, and the basic and clinical studies have been performed. The main findings obtained in the present study are: Amont 78 cases of CMZ administration immediately after the initial infection (A group), 42 remarkably effective (53.8%), 36 effective (46.2%) cass were observed. When other drugs were not effective after the initial infection, CMZ was administered (B group) to 24 cases, and 15 remarkably effective (62.5%), 9 effective (37.5%) cases were observed. overall effectiveness in the A and B groups was 57 remarkably effective (55.9%) and 45 effective (44.1%) cases, which are very excellent clinical effects. Among 102 cases, the pathogenic bacteria were found in 55 cases, and 29 cases out of the 55 (52.7%) showed infections with E. coli and with other bacteria having mixed infections. The effect of CMZ to E. coli as judged by MIC was excellent, providing the excellent clinical results. E. coli and other Gram-negative pathogenic bacteria in the B group showed resistance to ABPC, CEX, CEZ and CET, and after administering CMZ, all cases showed disappearance of these bacteria, but the increase in the resistant bacteria for CEX, CET and CEZ was obviously shown. Subjective and objective adverse effects and clinical laboratory analysis showed no abnormal effect and values due to CMZ, and it was true of the of the case received 140 g in total of CMZ over 35 days, 4 g/day. It may be conducted from the above findings that CMZ is very effective and safe antibiotic agent in the infections in the gynecoobsterics .