Water Distribution in Nafion Thin Films on Hydrophilic and Hydrophobic Carbon Substrates.

We performed H2O and D2O double-contrast neutron reflectivity measurements on ∼25 nm thick Nafion thin films on hydrophilic and hydrophobic carbon in water and 80% relative humidity vapor to investigate the depth profile of the water and Nafion distribution. We found a dense Nafion layer at the air or water interface regardless of the carbon hydrophilicity. On the other hand, a water-rich Nafion dense layer was observed at the carbon interface only for hydrophilic carbon. The double-contrast measurements provided quantitative information about the depth profile but simultaneously indicated that the sum of the volume occupancies of water and Nafion in the film was less than unity. We assessed the problem based on two possibilities: voids in the film or "residual water", which cannot be exchanged or is difficult to exchange with water outside.

Columnar metaplasia in the remnant esophagus is a long-term indicator for pneumonia after radical esophagectomy.

BACKGROUND: This study investigated the long-term risk factors for pneumonia after esophageal reconstruction using a gastric tube via the posterior mediastinal route following esophagectomy for esophageal cancer. The influence of columnar metaplasia in the remnant esophagus was specifically assessed. METHODS: Among 225 patients who underwent esophagectomy between January 2004 and December 2010, the subjects were 54 patients who could be followed up for more than 5 years. Routine oncologic follow-up consisted of CT scanning of the abdomen and chest every 4-6 months and annual endoscopy. Data on the occurrence of pneumonia were collected by retrospective review of chest CT scans. Risk factors for pneumonia investigated by univariate and multivariate analyses included the age, gender, diameter of the stapler, length of the intrathoracic remnant esophagus, anastomotic stricture, and presence of columnar metaplasia in the remnant esophagus. RESULTS: The median age was 62.4 years (interquartile range: 55.8-68.0 years). Forty-three patients were men. Pneumonia was detected in 39 patients (72.2%). The incidence of columnar metaplasia in the remnant esophagus increases with time. Anastomotic stricture was significantly related to the absence of columnar metaplasia on endoscopy in the first year after esophagectomy (p = 0.013). Univariate analysis showed that the frequency of pneumonia was significantly related to the intrathoracic remnant esophagus length ≥4.4 cm (p = 0.014), age over 65 years (p = 0.014), and the presence of columnar metaplasia in the remnant esophagus in the fifth year after esophagectomy (p = 0.005). Among them, age over 65 years and the presence of columnar metaplasia in the remnant esophagus in the fifth year after esophagectomy were found to be independent indicators of the postoperative pneumonia by multivariate analysis. CONCLUSION: Pneumonia occurred in 72.2% (39/54) of patients after esophagectomy for esophageal cancer. The presence of columnar metaplasia after esophagectomy is an indicator for pneumonia over the long term.

The diene-transmissive hetero-Diels-Alder reaction of 2-vinyl α,ß-unsaturated aldimines: stereoselective synthesis of hexahydroquinazolin-2-ones.

Stereoselective synthesis of hexahydroquinazolin-2(1H)-ones has been achieved through the application of the diene-transmissive hetero-Diels-Alder methodology to 2-vinyl-1-aza-1,3-butadienes. The cross-conjugated 1-azatriene underwent an initial hetero-Diels-Alder reaction on the 1-aza-1,3-butadiene system with tosyl isocyanate to afford the [4 + 2] mono-cycloadduct pyrimidinone. The second Diels-Alder reaction on the electron-rich 1-amino-1,3-diene unit of the mono-cycloadduct with dienophiles provided hexahydroquinazolin-2(1H)-ones with high stereoselectivity.

Primary esophageal mucosa-associated lymphoid tissue lymphoma treated by endoscopic submucosal dissection.

Primary esophageal mucosa-associated lymphoid tissue (MALT) lymphoma is rare. There have been few reports about early primary esophageal MALT lymphoma being treated endoscopically. The clinical profile of primary esophageal MALT lymphoma is currently unclear, so it is important to accumulate more information about early esophageal MALT lymphoma. To achieve early detection of esophageal MALT lymphoma, we need more accurate knowledge and information about the macroscopic and morphological features of this tumor. Endoscopic resection is one of the most effective treatments. With respect to the lateral and vertical margins of the resected specimen, endoscopic submucosal dissection (ESD) may be superior to endoscopic mucosal resection for treating early esophageal MALT lymphoma. Here we report the macroscopic appearance of the tumor which is the first successful case of ESD for early esophageal MALT lymphoma.

Molecular Epidemiological Characterization of Methicillin-Resistant Staphylococcus aureus from Bloodstream Infections in Northern Japan: Increasing Trend of CC1 and Identification of ST8-SCCmec IVa USA300-Like Isolate Lacking Arginine Catabolic Mobile Element.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major infectious disease pathogen, and its molecular epidemiological profile has been changing. In this study, a total of 279 MRSA isolates were collected from patients with bloodstream infection (BSI) in Hokkaido, northern main island of Japan, for a 2-year period from August 2019 to July 2021. CC5 (ST5/ST764)-MRSA-IIa (SCCmec-IIa) (47%, n = 132) and CC1 (ST1/ST2725/ST2764)-MRSA-IVa (42%, n = 116) were found to be major lineages, with CC8-MRSA-IVa being lower prevalence (5%, n = 13). CC1-MRSA-IVa showed a relatively increased proportion compared with our previous study (22%, 2017-2019). Seven isolates with SCCmec IVa (2.5%) were positive for Panton-Valentine leukocidin genes on ΦSa2usa and belonged to ST8/spa-t008/agr-I/coa-IIIa, showing genetic features of the USA300 clone. Among these isolates, six isolates harbored arginine catabolic mobile element (ACME) type I typical to the USA300 clone, while it was not detected in an isolate (strain R3-8). Whole genomic analysis of strain R3-8 revealed that its chromosome was highly similar to the USA300 strain TCH1516, but lacked ACME, carrying a plasmid genetically close to that of USA300 strains. The present study revealed increasing trend of CC1-MRSA-IV and occurrence of a novel variant of the USA300 clone among MRSA from BSI in northern Japan.

Comparative analysis of the outcomes of gastrectomy vs. endoscopic mucosal resection or endoscopic submucosal dissection for the treatment of gastric tube cancer after esophagectomy.

This study investigated the clinical characteristics of patients with gastric tube cancer following esophagectomy at our hospital, and to examine the outcomes of gastrectomy versus endoscopic submucosal dissection. Of 49 patients who underwent treatment for gastric tube cancer that developed 1 year or more after esophagectomy, 30 patients underwent subsequent gastrectomy (Group A), and 19 patients underwent endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) (Group B). The characteristics and outcomes of these two groups were compared. The interval between esophagectomy and diagnosis of gastric tube cancer ranged from 1 to 30 years. The most common location was the lesser curvature of the lower gastric tube. When the cancer was detected early, EMR or ESD was performed, and the cancer did not recur. In advanced tumors, gastrectomy was performed but the gastric tube was difficult to approach and lymph node dissection was difficult; two patients died as a result of the gastrectomy. In Group A, recurrence occurred most often as axillary lymph node, bone, or liver metastases; in Group B, no recurrence or metastases were observed. In addition to recurrence and metastasis, gastric tube cancer is often observed after esophagectomy. The present findings highlight the importance of early detection of gastric tube cancer after esophagectomy and that the EMR and ESD procedures are safe and have significantly fewer complications compared with gastrectomy. Follow-up examinations should be scheduled with consideration given to the most frequent sites of gastric tube cancer occurrence and the time elapsed since esophagectomy.

Prevalence, clonal diversity, and antimicrobial resistance of hypervirulent Klebsiella pneumoniae and Klebsiella variicola clinical isolates in northern Japan.

OBJECTIVES: Hypervirulent Klebsiella pneumoniae (hvKp) and Klebsiella variicola (hvKv) cause hospital/community-acquired infections, often associated with antimicrobial resistance (AMR). This study aimed to investigate the molecular epidemiology of hvKp and hvKv in northern Japan. METHODS: A total of 500 K. pneumoniae and 421 K. variicola clinical isolates collected from August to December 2021 were studied. Prevalence of virulence factor-encoding genes, wzi sequence and associated K/KL type, sequence type (ST), and beta-lactamases and their types were characterized. RESULTS: Any virulence gene (rmpA, rmpA2, peg-344, iucA, iutA, and iroB) and/or magA was detected in 25% (n = 125) of K. pneumoniae and 1% (n = 5) of K. variicola. Among these hvKp/hvKv, 22 wzi types (18 and 4 types, respectively) and 24 STs (20 and 4 STs, respectively) were identified. Sequence types of hvKp were classified into some clonal groups (CGs), among which CG35, including six STs, was the most common (n = 59; 47%), followed by CG23, and CG65. ST268 (CG35) associated with wzi95-K20 or wzi720 was the dominant lineage (n = 43, 34%), while K1:ST23/ST249 and K2:ST65/ST86 accounted for 26% and 13% of hvKp, respectively. Extended-spectrum beta-lactamase (ESBL) genes (blaCTX-M-2, blaCTX-M-3, blaCTX-M-15, and blaCTX-M-27) were detected in only ST23 and CG35 (ST268 and ST412) hvKp. No isolate was resistant to carbapenems, without detection of the ESBL gene in K. variicola. Phylogenetically, wzi was differentiated into two main clusters of K. pneumoniae and K. variicola. A major clonal group CG347 was identified in K. variicola. CONCLUSION: Clonal structures were revealed for hvKp and hvKv clinical isolates with their AMR status in northern Japan.

Antimicrobial Resistance, Virulence Factors, and Genotypes of Enterococcus faecalis and Enterococcus faecium Clinical Isolates in Northern Japan: Identification of optrA in ST480 E. faecalis.

Enterococcus faecalis and E. faecium are the major pathogens causing community- and healthcare-associated infections, with an ability to acquire resistance to multiple antimicrobials. The present study was conducted to determine the prevalence of virulence factors, drug resistance and its genetic determinants, and clonal lineages of E. faecalis and E. faecium clinical isolates in northern Japan. A total of 480 (426 E. faecalis and 54 E. faecium) isolates collected over a four-month period were analyzed. Three virulence factors promoting bacterial colonization (asa1, efaA, and ace) were more prevalent among E. faecalis (46-59%) than E. faecium, while a similar prevalence of enterococcal surface protein gene (esp) was found in these species. Between E. faecalis and E. faecium, an evident difference was noted for resistance to erythromycin, gentamicin, and levofloxacin and its responsible resistance determinants. Oxazolidinone resistance gene optrA and phenicol exporter gene fexA were identified in an isolate of E. faecalis belonging to ST480 and revealed to be located on a cluster similar to those of isolates reported in other Asian countries. The E. faecalis isolates analyzed were differentiated into 12 STs, among which ST179 and ST16 of clonal complex (CC) 16 were the major lineage. Nearly all the E. faecium isolates were assigned into CC17, which consisted of 10 different sequence types (STs), including a dominant ST17 containing multidrug resistant isolates and ST78 with isolates harboring the hyaluronidase gene (hyl). The present study revealed the genetic profiles of E. faecalis and E. faecium clinical isolates, with the first identification of optrA in ST480 E. faecalis in Japan.

Translational control analysis by translationally active RNA capture/microarray analysis (TrIP-Chip).

We have developed a new approach to systematically study post-transcriptional regulation in a small number of cells. Actively translating mRNAs are associated with polysomes and the newly synthesized peptide chains are closely associated with molecular chaperones such as hsp70s, which assist in the proper folding of nascent polypeptides into higher ordered structures. These chaperones provide an anchor with which to separate actively translating mRNAs associated with polysomes from free mRNAs. Affinity capture beads were developed to capture hsp70 chaperones associated with the polysome complexes. The isolated actively translating mRNAs were used for high-throughput expression profiling analysis. Feasibility was demonstrated using an in vitro translation system with known translationally regulated mRNA transcript thymidylate synthase (TS). We further developed the approach using HCT-116 colon cancer cells with both TS and p53 as positive controls. The steady-state levels of TS and p53 mRNAs were unaltered after 5-fluorouracil treatment as assessed by real-time qRT-PCR analysis. In contrast, the protein expression and polysome-associated mRNA levels of both genes were increased. These differences in translational rate were revealed with our new approach from 500 cells. This technology has the potential to make investigation of translational control feasible with limited quantities of clinical specimens.

Usefulness of clip traction in the early phase of esophageal endoscopic submucosal dissection.

BACKGROUND: The usefulness of clip traction in endoscopic submucosal dissection (ESD) for early esophageal carcinoma was investigated. METHODS: A total of 87 patients who underwent ESD for esophageal squamous cell carcinoma were included in the study. The hook knife method was used for ESD. Twenty patients underwent ESD without clip traction (non-clip group) and 67 underwent procedures in which clip traction was used (clip group). A clip with a string was attached to the oral edge of the lesion after mucosal incision in the clip group. RESULTS: ESD was successful in all cases. Wide exposure of the submucosal tissue below the lesion was obtained by applying tension to the clip traction. The duration of ESD was shorter in the clip group, and there was a significant difference in duration between the non-clip and clip groups. There were no complications of ESD in the clip group, but muscle layer injury occurred in three patients in the non-clip group. CONCLUSION: Clip traction shortens operating time and is safer in esophageal ESD. Clip traction is recommended as a useful auxiliary procedure.

Genetic characterization of penicillin-binding proteins of nonencapsulated Streptococcus pneumoniae in the postpneumococcal conjugate vaccine era in Japan.

OBJECTIVES: Nonencapsulated Streptococcus pneumoniae (NESp) is emerging after the introduction of pneumococcal conjugate vaccines (PCVs). This study aimed to elucidate the genetic characteristics of penicillin-binding proteins (PBPs; PBP1a, 2b, and 2x) associated with penicillin nonsusceptibility in emergent NESp. METHODS: A total of 71 NESp isolates that were identified in our previous study during the PCV era in Japan (2011-2019) were analyzed for their amino acid sequences of transpeptidase domain in PBP 1a, 2b, and 2x. RESULTS: Overall, we identified 21 different PBP profiles (1a-2b-2x), all of which represent novel PBP profiles. The dominant PBP profiles were 13-16-ne1 (32.4%, n = 23), ne1-16-ne2 (14.1%, n = 10), and 13-7-ne4 (7.0%, n = 5) (novel PBP type was numbered with "ne" denoting "nonencapsulated"), accounting for 53.5% of all isolates. All isolates with the PBP profiles 13-16-ne1 and 13-7-ne4 and those having PBP1a type-13 and -131, PBP2b type-7, -ne1, and -ne2 showed nonsusceptibility to penicillin. A high degree of genetic diversity was found in PBP2x, with most of them (81.7%) being new types. CONCLUSIONS: Our current study identified the 21 novel PBP profiles and remarkable mutations in the PBPs, which may be potentially associated with penicillin nonsusceptibility in NESp.

Cardiac metastasis after esophagogastrectomy for esophageal adenocarcinoma with an antemortem diagnosis.

Cardiac metastasis is uncommon and rarely diagnosed antemortem. Here, we describe a case of symptomatic cardiac metastasis from esophageal adenocarcinoma. A 64-year-old man developed chest symptoms 26 months after curative esophagogastrectomy for esophageal adenocarcinoma. Initially, ischemic cardiac disease was suspected based on electrocardiography findings, but an infiltrative tumor was seen morphologically in the wall of the interventricular septum and apex. No other lesions were detected. Histological examination of a transcatheter biopsy specimen indicated that the cardiac tumor was metastasis from esophageal adenocarcinoma. Chemoradiotherapy with cisplatin relieved his symptoms, and he had resumed normal activities. However, he opted not to undergo further aggressive treatment due to severe adverse effects from cisplatin. Seventeen months after completion of chemoradiotherapy, metastases to the right ventricle and the left thighbone were detected and he died 27 and 24 months after the diagnosis of cardiac metastasis and completion of chemoradiotherapy, respectively.

Clonal lineages and antimicrobial resistance of nonencapsulated Streptococcus pneumoniae in the post-pneumococcal conjugate vaccine era in Japan.

OBJECTIVES: The emergence and spread of nonencapsulated Streptococcus pneumoniae (NESp) is a public health concern in the post-pneumococcal conjugate vaccine era. We analyzed the prevalence, molecular characteristics, and antimicrobial resistance of NESp responsible for noninvasive infections in northern Japan. METHODS: NESp isolates were identified using molecular and phenotypical methods among 4463 S. pneumoniae isolates from noninvasive infection cases during 4 study periods between January 2011 and January 2019. NESp isolates were analyzed for antimicrobial susceptibility, genotype, and virulence-associated genes. RESULTS: Seventy-one NESp isolates were identified (1.6% of total clinical isolates) and assigned to the null capsule clade (NCC)1 (pspK+) (94.4%) or NCC2 (aliC+/aliD+) (5.6%). The dominant sequence types (STs) were ST7502 (23.9%), ST4845 (19.7%), ST16214 (11.3%), ST11379 (9.9%), and ST7786 (7.0%). These 5 dominant STs and all 7 novel STs were related to the sporadic NESp lineage ST1106 or PMEN clone Denmark14-ST230. High non-susceptibility rates of NESp were observed for trimethoprim-sulfamethoxazole, erythromycin, and tetracycline (>92.9%), and multidrug resistance was observed in 88.7% of the NESp isolates, including all ST7502, ST4845, and ST11379 isolates. CONCLUSIONS: The study revealed that the dominant clonal groups of NESp were associated with a high prevalence of non-susceptibility to antimicrobials in northern Japan.

Primary lymphoepithelioma-like carcinoma of the esophagus with metastatic lymph node and gastric cancer.

Upper gastrointestinal lymphoepithelioma-like carcinoma (LELC) is a rare disease-especially esophageal LELC (ELELC). Here, we report a surgically treated case of ELELC with gastric carcinoma. The patient was a 68-year-old asymptomatic Japanese man. Endoscopy revealed a submucosal-like protruding tumor located in the anterior wall of the esophagus 31-33 cm from the upper incisors and a slightly ulcerative lesion at the antrum of stomach. Histopathological diagnosis from biopsy of the esophageal lesion revealed a poorly differentiated squamous cell carcinoma; the stomach lesion was found to be well-differentiated tubular adenocarcinoma. CT showed a swollen lymph node along the left recurrent nerve. On the basis of a diagnosis of esophageal and gastric cancer, we performed esophagectomy with three-field lymph node dissection and partial gastrectomy. Histopathology of the resected esophageal tumor revealed solid nests of cancer cells, with substantial infiltration of lymphoid cells into the stroma. There were poorly differentiated cancer cells with large nuclei in the lymph node. In situ hybridization for Epstein-Barr virus showed no nuclear signal in the tumor cells. Immunohistochemistry gave a diagnosis of ELELC.

The role of oxygen-permeable ionomer for polymer electrolyte fuel cells.

In recent years, considerable research and development efforts are devoted to improving the performance of polymer electrolyte fuel cells. However, the power density and catalytic activities of these energy conversion devices are still far from being satisfactory for large-scale operation. Here we report performance enhancement via incorporation, in the cathode catalyst layers, of a ring-structured backbone matrix into ionomers. Electrochemical characterizations of single cells and microelectrodes reveal that high power density is obtained using an ionomer with high oxygen solubility. The high solubility allows oxygen to permeate the ionomer/catalyst interface and react with protons and electrons on the catalyst surfaces. Furthermore, characterizations of single cells and single-crystal surfaces reveal that the oxygen reduction reaction activity is enhanced owing to the mitigation of catalyst poisoning by sulfonate anion groups. Molecular dynamics simulations indicate that both the high permeation and poisoning mitigation are due to the suppression of densely layered folding of polymer backbones near the catalyst surfaces by the incorporated ring-structured matrix. These experimental and theoretical observations demonstrate that ionomer's tailored molecular design promotes local oxygen transport and catalytic reactions.

miR-192 Regulates dihydrofolate reductase and cellular proliferation through the p53-microRNA circuit.

PURPOSE: The purpose of this study is to investigate the molecular mechanism of miR-192 in colon cancer. EXPERIMENTAL DESIGN: Human colon cancer cell lines with different p53 status were used as our model system to study the effect of miR-192 on cell proliferation, cell cycle control, and mechanism of regulation. RESULTS: Our results show that one of the key miR-192 target genes is dihydrofolate reductase (DHFR). miR-192 affects cellular proliferation through the p53-miRNA circuit. Western immunoblot analyses indicated that the expression of DHFR was significantly decreased by miR-192. Further investigation revealed that such suppression was due to translational arrest rather than mRNA degradation. More profound inhibition of cellular proliferation was observed by ectopic expression of miR-192 in colon cancer cell lines containing wild-type p53 than cells containing mutant p53. Thus, the effect of miR-192 on cellular proliferation is mainly p53 dependent. Overexpression of miR-192 triggered both G1 and G2 arrest in HCT-116 (wt-p53) cells but not in HCT-116 (null-p53) cells. The cell cycle checkpoint control genes p53 and p21 were highly overexpressed in cells that overexpressed miR-192. Endogenous miR-192 expression was increased in HCT-116 (wt-p53) and RKO (wt-p53) cells treated with methotrexate, which caused an induction of p53 expression. Chromatin immunoprecipitation-quantitative reverse transcription-PCR analysis revealed that the p53 protein interacted with the miR-192 promoter sequence. CONCLUSION: These results indicate that miR-192 may be another miRNA candidate that is involved in the p53 tumor suppressor network with significant effect on cell cycle control and cell proliferation.

Association Between Pneumococcal Surface Protein A Family and Genetic/Antimicrobial Resistance Traits of Non-Invasive Pneumococcal Isolates from Adults in Northern Japan.

Pneumococcal isolates from adult patients in northern Japan in 2016 were subjected to molecular investigation related to pneumococcal surface protein A (PspA) and drug resistance determinants. Of the 51 isolates, serotype 3/ST180 was the most prevalent (17.6%), followed by 35B (ST2755/ST558) (11.8%) and 15A (ST63/ST7874/ST13068/ST13785) (9.8%). Coverage of serotypes by 13-valent conjugate vaccine and 23-valent polysaccharide vaccine was 27.5% and 49%, respectively. All the isolates expressed PspA family 1 or 2 (51% and 49%, respectively). Each serotype was associated with either of the PspA families (e.g., serotype 3, PspA family 1; serotypes 35B and 15A, PspA family 2). Multidrug resistance (MDR) was found in 84.3% of the isolates. Minimum of one altered penicillin-binding protein gene was detected in 82.4% of isolates, indicating 25.5% non-susceptibility to penicillin. Serotypes 15A and 35B were predominant and demonstrated MDR. An isolate of serotype 15A/ST13785 (single-locus variant of ST242) was resistant to fluoroquinolones associated with double mutation in the quinolone resistance-determining regions of gyrA and parC. The present study indicates the spread of MDR pneumococci represented by isolates of serotypes 3, 15A, and 35B, and prevalence of both PspA family 1 and 2 in isolates obtained from adult patients.

Regulation of p53 expression in response to 5-fluorouracil in human cancer RKO cells.

PURPOSE: The purpose of the study is to investigate the regulation of p53 expression in response to 5-fluorouracil (5-FU) in human colon cancer cells. EXPERIMENTAL DESIGN: Human colon cancer RKO cells were used as our model system. The levels of p53 expression and p53 protein stability in response to 5-FU and doxorubicin were investigated. In addition, the acetylation and phosphorylation status of p53 after 5-FU and doxorubicin treatment was analyzed by Western immunoblot analysis. RESULTS: Treatment of human colon cancer RKO cells with 10 micromol/L 5-FU resulted in significantly increased levels of p53 protein with maximal induction observed at 24 h. The level of acetylated p53 after 5-FU exposure remained unchanged, whereas the phosphorylated form of p53 was expressed only after 24 h drug treatment. Northern blot analysis revealed no change in p53 mRNA levels after 5-FU treatment. No differences were observed in the half-life of p53 protein in control and 5-FU-treated cells, suggesting that the increase in p53 was the direct result of newly synthesized protein. In contrast, the maximal induction of p53, in response to doxorubicin, occurred at an earlier time point (4 h) when compared with cells treated with 5-FU (24 h). No corresponding change in p53 mRNA was observed. Levels of both the acetylated and phosphorylated forms of p53 were markedly increased upon doxorubicin exposure when compared with treatment with 5-FU, resulting in a significantly prolonged half-life of p53 (120 versus 20 min). CONCLUSION: These results, taken together, suggest that the regulatory mechanisms controlling p53 expression, in response to a cellular stress, are complex and are dependent upon the specific genotoxic agent. With regard to 5-FU, we show that translational regulation is an important process for controlling p53 expression. Studies are under way to define the specific mechanism(s) that control 5-FU-mediated translational regulation of p53.

Genetic diversity of pneumococcal surface protein A (PspA) in paediatric isolates of non-conjugate vaccine serotypes in Japan.

PURPOSE: Among the pneumococcal proteins, pneumococcal surface protein A (PspA) is considered the most promising candidate for a serotype-independent vaccine. This study aimed to investigate the serotype, genetic diversity of PspA, lineage (genotype) and drug resistance traits of pneumococcal isolates from paediatric patients. METHODOLOGY: A total of 678 non-invasive pneumococcal isolates obtained from June to November 2016 were analysed. All isolates were characterized for PspA families, serotypes and macrolide resistance genes. Seventy-one representative isolates of non-vaccine serotypes (NVTs) were genetically analysed for the clade-defining region (CDR) of PspA, as well as multi-locus sequence typing (MLST). RESULTS: The detection rate of NVTs was 87.9 % (n=596), including dominant NVTs 15A (14.5 %, n=98), 35B (11.8 %, n=80), 15C (9.3 %, n=63) and 23A (9.0 %, n=61). Most isolates (96.6 %) possessed macrolide resistance genes erm(B) and/or mef(A/E). PspA families 1, 2 and 3 were detected in 42.3, 56.6 and 0.6 % of isolates, respectively. Nucleotide sequences of CDR showed high identity (90-100 %) within the same PspA clade, although the CDR identity among different PspA families ranged from 53 to 69 %. All isolates of NVTs 23A, 10A, 34, 24, 22F/22A, 33F, 23B and 38 were from PspA family 1, while NVTs 35B, 15C, 15B and 11A/11D isolates were from family 2. In contrast, genetically distinct PspAs were found in NVTs 6C and 15A. PspA family 3/clade 6 was detected in only NVT serotype 37 isolates assigned to ST447 and ST7970, showing the mucoid phenotype. CONCLUSION: The present study revealed the predominance of PspA families 1 and 2 in NVTs, and the presence of family 3 in serotype 37.