Japanese encephalitis (JE) surveillance has been conducted since 1965 as a part of the National Epidemiological Surveillance of Vaccine Preventable Diseases in Japan. Over 1,000 JE cases were reported annually in the late 1960s. The number of JE cases has since markedly decreased, with less than 10 cases reported annually from 1992 to 2004. A total of 361 JE cases were reported between 1982 and 2004. Prognosis was available for 320 cases; 58 (18%) died, 160 (50%) recovered with neuropsychiatric sequelae, and 102 (32%) completely recovered. Seventy-eight percent of these cases were 40 years old or over with a peak age group of 60-69 years old. JE predominantly occurred in unvaccinated populations. A high seroconversion rate among sentinel pigs was recorded every year. This suggests the presence of JE virus-infected mosquitoes during the summer in most areas of Japan, including the northern districts where no JE cases were reported from 1982 to 2004. Although JE cases have been reported in single figures since 1992, the risk of JE virus infection is still present. Thus, high immunization rates of JE vaccine should be maintained in Japan.

The identification of microorganisms causing ventilator-associated pneumonia (VAP) is important for formulating appropriate therapies. In this study, we report the incidence, etiology, and antibiotic resistance patterns of Gram-negative microorganisms isolated from patients diagnosed with VAP in our medical-surgical intensive care unit (ICU) during the years 2004-2006. VAP was diagnosed by using the clinical criteria of the Centers for Disease Control and Prevention. Antibiotic resistance patterns of isolated microorganisms were defined by standard methods. The VAP incidence rate was 22.6/1,000 ventilator days. The most frequently isolated pathogens were Acinetobacter spp., methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa. Ninety percent of Acinetobacter spp. isolates were resistant to ceftazidime, 64% to imipenem, and 80% to ciprofloxacin. Fifty-nine percent of P. aeruginosa isolates were resistant to ceftazidime, 32% to imipenem, and 62% to ciprofloxacin. Cefoperazone-sulbactam was the most active agent against Acinetobacter spp. In conclusion, the incidence of VAP and the prevalence of multidrug-resistant microorganisms are quite high in our ICU. Comparison of the resistance rates of isolates demonstrates that certain antibiotic agents are more effective than others.

This work studies antimicrobial resistance and class 1 integrons of Aeromonas spp. in human isolates from southern Taiwan. PCR amplification and DNA sequence analyses were performed to characterize the gene cassette regions of the class 1 integron in 204 isolates of Aeromonas hydrophila, 36 isolates of A. sobria, 23 isolates of A. veronii, and 4 isolates of A. caviae. By using Southern hybridization with an intI1 probe to determine the presence of class 1 integrons in the 9 isolates of Aeromonas spp. harboring plasmid DNA, only 2 isolates, one A. veronii AV69 harboring 176-kb plasmid DNA, and one A. hydrophila AH207 harboring 149-kb plasmid DNA were identified. A conjugation experiment was carried out with 2 isolates of A. veronii AV69 and A. hydrophila AH207. Only one transconjugant of Escherichia coli AH207, containing 149-kb plasmids obtained from A. hydrophila AH207, was identified. ERIC-PCR analysis was performed to analyze the genetic relatedness in all isolates of Aeromonas spp. that carry class 1 integrons. The results of cluster analysis in this experiment revealed that none of these isolates were clonal, which may indicate that they were not related to the outbreak. Among the 267 isolates tested, class 1 integrons were detected in 37 isolates (13.9%) of Aeromonas spp. from humans. No class 2 or class 3 integrons were detected in this study. Gene cassette structures were identified in 30 (81.0%) of 37 isolates of Aeromonas spp. containing class 1 integrons. The gene cassette of dfrA12-orfF-aadA2 was the most prevalent in the gene cassette array (16.0%), followed by arr3-aacA4 (13.3%) and dfr2d-catB3-aadA1 (10.0%). Four novel arrays of gene cassettes were also identified, namely, dfr2d-catB3-aadA1, aadA1-aac(6')-II, aadA4a, and aac(6')-II-blaOXA-21-catB3. This is the first report of Aeromonas spp. isolates from humans.

Bacteriological analysis of 1,551 stool/rectal swabs from all age groups of diarrhea patients of different hospitals of Orissa from January 2004 to December 2006 was carried out using standard procedures. Among all enteropathogens isolated in 886 culture-positive samples, Escherichia coli constituted 75.5%, including 13.2% pathogenic E. coli; Vibrio cholerae O1 constituted 17.3%; V. cholerae O139, 1%; Shigella spp., 4.5% (Shigella flexneri type 6, 2.9%, S. dysenteriae type 1, 0.7%, S. sonnei, 0.6%, and S. boydii, 0.3%); Salmonella spp., 0.7%; and Aeromonas spp., only 2.0%. The isolation of bacterial enteropathogens was highest during July, 2005, followed by September, 2006. The prevalence of shigellosis in this region was relatively low. Cholera cases were more frequent during the rainy seasons. The dominance of V. cholerae O1 Inaba over Ogawa serotypes was observed in 2005, whereas this trend was reversed in 2006. The resistance profile of V. cholerae O1 was co-trimoxazole (Co), furazolidone (Fr), and nalidixic acid (Na); for Aeromonas spp., it was ampicillin (A), Fr, ciprofloxacin (Cf), Na, norfloxacin (Nx), and Co. Pathogenic E. coli strains were resistant to A, Fr, Co, streptomycin (S), Cf, Na, Nx, and neomycin (N); Shigella spp. were resistant to Fr, Na, Co, and S; and Salmonella spp. were resistant to A and Fr. Active surveillance should be continued among diarrhea patients to look for different enteropathogens and to define the shifting antibiogram patterns in this region.

The relationship between the incidence of bacillary dysentery and meteorological factors was investigated. Data on bacillary dysentery incidence in Shenyang from 1990 to 1996 were obtained from Liaoning Provincial Center for Disease Control and Prevention, and meteorological data such as atmospheric pressure, air temperature, precipitation, evaporation, wind speed, and the amount of solar radiation were obtained from Shenyang Meteorological Bureau. Kendall and Spearman correlations were used to analyze the relationship between bacillary dysentery and meteorological factors. The incidence of bacillary dysentery was treated as a response variable, and meteorological factors were treated as predictable variables. Software R 2.3.1 was used to execute the classification and regression trees (CART). The model improved the accuracy of the fitting results. The residual sum square error of the regression tree model was 53.9, while the residual sum square error of the multivariate linear regression model was 107.2. Among all the meteorological indexes, relative humidity, minimum temperature, and pressure one month prior were statistically influential factors in the multivariate regression tree model. CART may be a useful tool for dealing with heterogeneous data, as it can serve as a decision support tool and is notable for its simplicity and ease.

This study sought to investigate the impacts of the antiretroviral (ARV) therapy regimens currently used in Chinese HIV-1-infected individuals. Seven hundred eighteen ARV-treated and treatment-naïve HIV-1-infected individuals living in seven provinces were enrolled in 2005 by a multistage sampling approach according to a national cross-sectional survey program on HIV-1 drug resistance. All patients were investigated clinically, and CD4+ T cell counts and HIV-1 viral loads were measured while genotyping for drug resistance was determined by a home brew nested PCR. Viral inhibition in ARV-treated individuals was higher than that in ARV treatment-naïve individuals. The overall prevalence of drug-resistant mutations was 37.8%. Higher frequencies of mutations in ARV-treated and drug withdrawal groups were found than in the ARV treatment-naïve group (P < 0.01). Of the four regimens currently used, the D4T/3TC/NVP regimen showed a higher-level viral inhibition. No statistical significance was found among the four regimens in drug-resistant mutations. The rate of resistance-associated mutations to non-nucleotide reverse transcriptase inhibitors (NNRTIs) was higher than that to nucleotide reverse transcriptase inhibitors (NRTIs) (P < 0.01). The most common mutations conferring resistance to NNRTIs were K103N, Y181C and G190A, representing 56.5, 30.4 and 14.5%, respectively. Furthermore, higher viral inhibition and a lower rate of drug-resistant mutations were achieved in the good compliance group. This study revealed an efficient viral inhibition achieved with the current first-line regimens in China. Most of these regimens could rapidly result in emergence of drug-resistant mutations, suggesting that a second-line ARV therapy is urgently needed and that the compliance with treatment must be emphasized during long-term treatment.

This study was performed to evaluate commercial brucella immunoglobulin G and M enzyme-linked immunosorbent assay (IgG and IgM ELISA) kits for the diagnosis of human brucellosis and to suggest a candidate prognostic marker for human brucellosis. We determined the serum levels of brucella IgG, IgM, C-reactive protein (CRP), soluble CD14 (sCD14), and neopterin in patients with brucellosis and compared them with those of normal healthy persons, patients with tuberculosis, and patients with other diseases. It was found that the sensitivity of ELISA to diagnose brucellosis was high when both IgG and IgM ELISA were used together. This study showed that serum CRP, sCD14, or neopterin levels were significantly high during the course of human brucellosis. The above markers, alone or in combination, might have the potential to evaluate treatment outcomes in human brucellosis. The markers that can predict the variability of agglutination titer was also determined. It was found that the titer value alone does not fully represent disease status.

This study comparatively evaluated the titers of the bacterial agglutination (BA) antibody for Bordetella pertussis, anti-pertussis toxin (PT) antibody, and anti-filamentous hemagglutinin (FHA) antibody in the serum of medical staff members. The geometric means of the anti-PT and anti-FHA antibody titers were 5.83 and 17.17 EU/mL, respectively. The positive rates of the BA antibodies against Tohama and Yamaguchi strains (≥40x), and anti-PT and anti-FHA antibodies (≥10 EU/mL) were 81.3, 72.9, 43.8, and 68.8%, respectively. A high anti-PT antibody titer (>94 EU/mL) was found in 1 staff member, but this individual had no recent respiratory symptoms. The titers of the BA antibody against the Yamaguchi strain were weakly associated with the anti-PT antibody titers, but the BA antibody titer was not useful for predicting anti-PT antibody positivity. The seroprevalence of anti-pertussis antibody among medical staff was heterogeneous, suggesting that this group could be at high risk for pertussis. Judgments made using BA antibody or anti-PA antibody results differ, and thus careful evaluation of anti-pertussis antibody titers is necessary. Prompt and accurate diagnostic tools are crucial for infection control in the hospital setting.

Biofilms play an important role in the establishment of chronic infection caused by Pseudomonas aeruginosa. It has been suggested that membrane vesicles (MVs) are released into the surrounding medium during normal growth and might supply the bacterial extracellular DNA that is required for early biofilm formation, as MVs released from the bacterial outer membrane are suspected to be the source of extracellular DNA. MVs possess lipopolysaccharide (LPS), extracellular DNA, and several hydrolytic enzymes. It is well known that the quorum-sensing (QS) system is important in controlling virulence factors in P. aeruginosa and biofilm formation. In the current study, we investigated extracellular LPS and DNA in the supernatants of culture solutions from PAO1, the wild-type P. aeruginosa, and those of QS mutants. As compared to that of las QS mutants, the amount of LPS and DNA released was significantly higher in PAO1 and in las QS mutants complemented with N-(3-oxododecanoyl) homoserine lactone. Our study indicated that the QS is among the regulators involved in the release of extracellular DNA and LPS. It is possible that these extracellular components are supplied from MVs. Investigation of the mechanism of biofilm formation is of particular interest, as it may be useful for designing treatments for severe P. aeruginosa infection.

We report a rare case of Legionella pneumophila pneumonia followed by invasive aspergillosis (IA). Legionellosis was ameliorated by the administration of ciprofloxacin, erythromycin, and corticosteroid as adjunctive therapy. Although intravenous administration of the corticosteroid was effective at reducing severe inflammation due to legionellosis, IA occurred at 12 days after admission. Combination therapy with micafungin and voriconazole was effective in this case; however, it remains necessary to exercise caution when making decisions regarding indications for corticosteroid use and observation in the treatment of severe pneumonia patients.

Group B streptococcus (GBS) is the most common pathogen in neonates and may induce the overproduction of cytokines. To further clarify temporal alterations in the levels of various cytokines/chemokines, we measured the concentrations of 16 types of these immunological responders in the serum of a neonate presenting with GBS infection. At birth, the concentrations of different cytokines/chemokines increased and that of granulocyte colony-stimulating factor remained high. Thus, these cytokines/chemokines might be associated with the pathophysiology of GBS infection.

The objective of the study was to analyze the epidemiological features of hemorrhagic fever with renal syndrome (HFRS) in Montenegro. The study included 169 cases of HFRS diagnosed in the period between 1995 and 2005 according to the clinical symptoms and serological confirmation. For the analysis of the demographic characteristics of the cases, as well as of the chronological and topographical features of the disease, a descriptive epidemiological method was employed. The average incidence rate in the observed period was 2.6 per 100,000. In the observed period, 8 people died; the average case fatality rate was 4.8% (range: 0.1-15%). Among the diseased persons, 116 were males and 53 were females; most of the cases were adults. The greatest number of HFRS cases occurred during the summer months. The highest incidence rates were registered in the northeastern, rural part of the country. The most frequent type of hantaviruses in Montenegro were Dobrava-Belgrade and Hantaan, carried by rodent species, i.e., the yellow-neck mouse and the striped-field mouse. It is likely that HFRS in Montenegro will become more common in the near future, unless public health control measures are taken.

We investigated a nosocomial infection of severe acute respiratory syndrome (SARS) in Vietnam in 2003 and attempted to identify risk factors for SARS infection. Of the 146 subjects who came into contact with SARS patients at Hospital A, 43 (29.5%) developed SARS, and an additional 16 (11%) were asymptomatic but SARS-coronavirus (CoV) seropositive. The asymptomatic infection rate accounted for 15.5% of the total number of infected patients at Hospital A, which was higher than that of 6.5% observed at Hospital B, to where all patients from Hospital A were eventually transported (P < 0.05). At Hospital A, the risk for developing SARS was 12.6 times higher in individuals not using a mask than in those using a mask. The SARS epidemic in Vietnam resulted in numerous secondary infections due to its unknown etiology and delayed recognition at the beginning of the epidemic. The consistent and proper use of a mask was shown to be crucial for constant protection against infection with SARS.

Forty-five antiretroviral-naïve HIV-1 infected patients and 14 healthy controls in North China were enrolled in this study. The frequency of CD4+CD25+Foxp3+ regulatory T cells (Tregs) and levels of expression of CD95, HLA-DR and CD38 in T cells were detected by flow cytometry. We found that the frequency of Tregs was higher in AIDS patients than in asymptomatic HIV-1 infected patients (P = 0.004). The frequency of Tregs was significantly correlated with absolute CD4 count, viral load, CD4+CD95+ T cells and CD8+CD95+ T cells (P < 0.05). The relationship between the frequency of Tregs and immune activation was not found in HIV-infected patients. We concluded that the frequency of Tregs in HIV-infected Chinese patients was significantly correlated with disease progression.

To assess the spread and genetic characteristics of Panton-Valentine leukocidin (PVL) gene-carrying Staphylococcus aureus in Bangladesh, we investigated 59 strains (49 isolates from clinical specimens and 10 isolates colonized in the nasal cavities of medical staff), including 26 methicillin-resistant S. aureus (MRSA) strains. The PVL gene was detected only in methicillin-susceptible S. aureus (MSSA) strains (7 clinical strains and 2 colonizing strains). PVL gene-positive MSSA strains were found to belong to coagulase serotypes III or VI and were classified into sequence types ST88 (CC88), ST772, and ST573 (CC1) by multilocus sequence typing, and agr types 2 or 3. These types were different from those determined for MRSA (coagulase serotypes I and IV, ST240 and ST361, and agr type 1). PVL gene-positive MSSA possessed a larger number of virulence factor genes than MRSA, although they were susceptible to more antimicrobials. These findings suggest that the PVL gene is distributed to limited populations of S. aureus clones with specific genetic traits that are distinct from MRSA in Bangladesh, but genetically close to CA-MRSA clones in the CC1 lineage reported in the United States and European countries.

This study was designed to evaluate the serologic response to Mycoplasma pneumoniae infection. A total of 589 children ≤18 years (190 in the year 2004; 399 in 2005) and 2,073 adults ≥18 years of age (980 in the year 2004; 1,093 in 2005) with respiratory symptoms underwent serological testing for M. pneumoniae infection. The tests included passive particle agglutination (PA) and enzyme-linked immunosorbent assay (ELISA). The seroprevalence rates of M. pneumoniae infection in the years 2004 and 2005 were 6.9 and 10.1%, respectively. The seropositivity rate was significantly higher in children (29.6% in 2005; 23.7% in 2004) than in adults (2.9% in 2005; 3.7% in 2004) (odds ratio, 8.138 in 2004; 13.923 in 2005; 95% confidence interval, 5.077-13.045 in 2004; 9.220-21.026 in 2005). Paired sera for the PA test were obtained from 32 of 399 children, and 22 of them demonstrated at least fourfold rises in antibody titer. ELISA had a sensitivity of 77.3% and a specificity of 40.0%; PA had a sensitivity of 9.5% and a specificity of 80%. The ELISA test was superior to the PA test in diagnosing acute M. pneumoniae infection in children. Both tests were significantly more sensitive when they were performed 1 week after the onset of infection.

In a population-based study we investigated the early-onset, invasive sepsis caused by group B streptococcus (GBS) and non-GBS in the era of intrapartum antimicrobial prophylaxis. From 1998 to 2006, we had 387 perinatal deaths in 98,495 deliveries, and 9 full-term infants met the criteria of early-onset, invasive sepsis, in which microorganisms were proven from blood sampling. Of these cases, 4 involved GBS, 2 ampicillin-resistant Escherichia coli, 2 methicillin-resistant Staphylococcus aureus, and 1 was unidentified. All 4 cases of GBS related death underwent improper procedures contrary to the prophylaxis recommendation. Eighty percent of non-GBS related deaths had septicemia of antibiotic-resistant pathogens. We found in our population-based study that early-onset, fatal sepsis in full-term infants is associated with insufficient adherence to the prophylaxis strategy for GBS and with the emergence of antimicrobial resistant non-GBS bacteria.

Bacterial pathogens manipulate host cells to promote pathogen survival and dissemination. In this study, microarray technology was used to identify the genes that are affected by the Vibrio vulnificus quorum-sensing genes, luxS and smcR. By comparing the expression profiles of mouse macrophage cell lines stimulated with either the parent strains or a luxS smcR mutant, differentially expressed genes were identified. The genes included those that affect host cell death, stress, signaling transduction, inflammation, and immune response. Macrophages stimulated with the luxS smcR mutant differentially expressed genes associated with removal of toxins, the complement pathway, regulation of cytokine expression, and antigen presentation, indicating that macrophages stimulated with the luxS smcR mutant induced an appropriate inflammation reaction and immune response for removal of bacteria. In summary, quorum-sensing in V. vulnificus could contribute to bacterial survival and increased pathogenesis by inducing a changed expression profile in macrophages.

Duplex PCR is useful for detecting two different agents from the same specimen. Kidney specimens are the most suitable for detection of Leptospira spp. For Orientia tsutsugamushi, blood clots, spleen, and liver specimens are considered the most suitable. For this study, kidney tissues were the only specimens obtainable for the PCR. Blood clots, spleen, and liver specimens were not available. However, by using the PCR for scrub typhus, O. tsutsugamushi was detected in the kidney of one rodent. This result shows that kidney specimens can be used to detect O. tsutsugamushi using PCR. Further studies will be necessary in order to be able to compare the detection ratio of O. tsutsugamushi using kidney specimens and blood clots, spleen, and liver specimens.

Flavivirus membranes fuse with cellular membranes by low pH-induced mechanisms. Although Japanese encephalitis virus (JEV) has similar mechanisms, fusion induced under neutral conditions has been observed. We report herein polykaryocyte formation using Vero cells infected with recombinant vaccinia viruses, vP829 expressing JEV premembrane (prM) and envelope (E), or vP555 expressing prM, E, and the nonstructural proteins NS1 and NS2A. Polykaryocytes were detected under pH 7.0 as early as 9 h after infection. Higher fusion indices were shown with vP555 than vP829. A monoclonal antibody to E suppressed vP829/vP555-induced polykaryocyte formation. Polykaryocytes were also formed under alkaline conditions (pH 8.0).

We report the case of a 1-year-old boy with an infected subdural hematoma due to Streptococcus pneumoniae identified by latex agglutination test and polymerase chain reaction amplification of a bacteria-specific gene. The present case demonstrated the need to include infected subdural hematoma in the differential diagnosis of suspected subdural empyema, and suggested the usefulness of combining these methods to identify a causative organism.

We conducted a contact investigation in a psychiatric hospital to evaluate the nosocomial transmission of tuberculosis (TB). Contacts included hospital healthcare workers (HCWs) and inpatients who had been exposed to an index case of pulmonary TB. Contacts were evaluated for Mycobacterium tuberculosis infection with standard screening methods as well as the QuantiFERON^®-TB Gold (QFT-G) test. A tuberculin skin test (TST) was administered to 3 individuals who were under 30 years old, and all tests were negative. Chest X-ray examination was performed for all 46 contacts (9 HCWs and 37 patients). Five had abnormal chest X-ray results that were not compatible with TB, and 41 had normal chest X-rays. As regards the QFT-G test, 23 of the 46 (50%) contacts, 1 HCW (an 81year-old male) and 22 patients, were positive. The results suggest that there was significant nosocomial transmission of TB infection among inpatients in this psychiatric hospital. Moreover, these findings indicate that the use of chest X-ray and TST, i.e., conventional methods of detection will leave TB infection undetected in many individuals. Thus, introduction of screening for TB infection using the QFT-G test in long-term care facilities such as psychiatric hospitals may enable the detection and treatment of individuals with latent TB in whom the infection would otherwise be missed by other conventional screening methods.

A large number of gastroenteritis outbreaks due to a norovirus GII/4 strain and its variants occurred during November and December 2006 in Kobe, Japan. Of the 118 outbreaks, 6 were foodborne and 112 were caused by person-to-person transmission in healthcare settings such as nursing homes and hospitals. The distribution of norovirus outbreaks in healthcare settings was skewed, particularly in the south coastal area. Moreover, several outbreaks occurred within 1 km² in various areas. Outbreaks in neighboring settings, especially within 1 km, and travel from the sources of outbreaks were risk factors for the spread of the norovirus. The use of ineffective disinfectants such as alcohol and benzalkonium chloride might also have helped to spread the infection.