Respiratory syncytial virus (RSV) antigen-detection kits are used in clinical settings in Japan. Here, we compared the sensitivities of 12 different kits that are commercially available in Japan. Notably, these kits were developed based on the principle of immunochromatography. The comparison was performed using six different test specimens：standard laboratory strains of RSV subgroups A and B, and clinical specimens of nasal aspirates from patients infected with RSV subgroups A or B. The specimens were serially diluted with medium at half log concentration, and the dilutions were applied to the kit tests. The minimum detection limit was determined for each kit and for every specimen by investigating the maximum dilution rate for acquiring positive result. The absolute minimum detection limits were calculated based on the viral RNA copy number of the specimens and the maximum dilution rate ranged from 10⁷ to 10⁹ copies/mL, depending on the specimens and kits. Thus, the sensitivity was revealed to differ among the viral specimens examined using each kit and among the kits used to examine each viral specimen, though the difference was not significant and revealed a maximum of only 10 times. The results were compared with the geometric mean values of the results for all 12 kits which were separately calculated for all 6 specimens. Consequently, some kits with lower or higher sensitivities to all the tested specimens were identified, suggesting that some general differences in sensitivity exist among commercially available RSV antigen-detection kits, although the differences are not significant. Of course, selecting kit with a higher sensitivity would be preferable, but no large differences in sensitivity among the available kits examined in the current study. Therefore, other factors such as cost-effectiveness, convenience, time required for testing, etc., can be taken into account when selecting a kit for use in clinical settings.

View full abstract

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) for elderly people has been included in the National Immunization Program (NIP) of Japan since October 2014. Targets for PPSV23 were restricted to persons ≧65 years of age and persons 60 to 64 years of age with an underlying severe physical disability (expressed as 1^st grade in Japan). In this study, the clinical courses of non-target persons ＜65 years of age were compared between those with non-severe underlying diseases (A group) and those without underlying diseases (B group), and the need to expand the targets for PPSV23 within the NIP was investigated. Persons with pneumococcal pneumonia who were diagnosed based on a positive sputum or blood culture result were enrolled between January 2004 and April 2014. As a result, the number of subjects in A group was 2.6 times larger than that in B group, and this difference was especially pronounced (4.2 times) among subjects between the age of 60 to 64 years. These findings suggest that persons with underlying disease without a 1^st grade physical disability might also be susceptible to pneumococcal pneumonia. No significant differences in the severity of pneumonia, the length of treatment, or the rates of admission were seen between A group and B group. The severity of pneumonia and the rates of admission among targets of the NIP were significantly higher than those of A group. In conclusion, our study suggests that A group should also be included among the targets of the NIP and that all targets eligible to receive the pneumococcal vaccine within NIP should be inoculated.

View full abstract

　We performed a retrospective study examining adult patients with RSV infection who were diagnosed at our hospital during two consecutive winter seasons, 2011-2012 and 2012-2013；these patients were compared with, adult patients who had been diagnosed as having influenza during the same periods. RSV infection was confirmed by a 4-fold increase in the CF antibody titer, while influenza was diagnosed based on a rapid antigen test. Forty-three patients with RSV infection and pneumonia patients (39 inpatients and 4 outpatients) and 25 patients with influenza and pneumonia (23 inpatients and 2 outpatients) were detected. Overall, 54 patients with RSV infection and 42 patients with influenza, were hospitalized during the two seasons. A history of the influenza vaccination was verified for 48% of the influenza patients with pneumonia and 35% of the non-pneumonia influenza patients who were hospitalized, and neuraminidase inhibitors were used for the treatment of all the influenza patients and 88% of the non-pneumonia influenza patients who were hospitalized. Overall, 5.3% of the adult cases with pneumonia (43/817) during the two seasons were diagnosed as having RSV related illness, and within the peak period, in particular, 14.6% were judged as having RSV pneumonia. Furthermore, 63% of the patients with RSV infection and pneumonia had mixed infections with other common respiratory pathogen, such as Streptococcus pneumoniae, and within the peak period,almost 15% of the patients with pneumonococcal pneumonia were confirmed to have mixed infections that included RSV. In both groups, one-fourth of the patients had been living in nursing homes or had been receibing home medical care. Up to 20% of the RSV pneumonia patients were initially diagnosed as having aspiration pneumonia. We suspect that some of these elderly patients might have developed pneumonia as a result of preceding viral infection or following vomiting or aspiration. The overall clinical picture, such as the mean age, maximum body temperature, hypoxemia, CRP, and WBC, did not differ significantly between the two groups. The 30-day mortality and overall hospital mortality rates were similar in both groups, but the lengths of the hospital stay were significantly longer, and several patients survived but continued to have a reduced activities of daily living score at the time of their discharge in the RSV pneumonia group.

View full abstract

Salmonella is a major causative agent of food borne diseases. Recently, monophasic strains of Salmonella,such as S. enterica 4：i：-, have been frequently reported. Here, we investigated the genetic background of S. enterica 4：b：- using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis. A total of 10 strains of S. enterica (I) 4：b：- were examined and compared with 34 strains including serovar Paratyphi B and Paratyphi B var Java, Schleissheim, and II b：-. All I 4：b：- strains were negative for hin which encodes an invertase that converts the H phases, and six were also negative for fljB, which encodes the second phase of the H antigen. An MLST analysis identified 12 sequence types (ST) and 6 ST complexes (STC) from the 44 strains. A clustering analysis of PFGE patterns almost corresponded to the STC. The monophasic I 4：b：- strains were assigned to 3 STCs (19, 32 and 155), corresponding to those of Paratyphi B var. Java or a monophasic strain according to the data of this and previous studies. These findings suggest that the monophasic strains examined in this study might have been derived from multiple clones of Paratyphi B var Java. This study shows the usefulness of molecular typing as complementation tools of the conventional serotyping system.

View full abstract

Blackwater fever (BWF), which causes massive intravascular hemolysis and the passage of blackcolored urine, is a poorly understood condition that is rarely seen during the course of malaria. Here, we present a case of BWF that developed after treatment for falciparum malaria complicated by hyperparasitemia in a Japanese traveler. A 29-year-old woman returning from Ghana visited our travel clinicwith complaints of sudden fever and headache on the third day of illness. She had taken anti-malarial drugs for intermittent malaria prophylaxis and the treatment of malariawhile in Ghana. Falciparum malaria was diagnosed based on the results of a blood smear and was confirmed using PCR. She was successfully treated with a single artesunate suppository and one dose of intravenous quinine followed by artemether-lumefantrin for 3 days. She was discharged without complications on the 11th day of illness. However, she was re-admitted for fever and headache on the 16th day of illness. The recrudescence of malaria was excluded by peripheral blood smear results. BWF was diagnosed based on the presence of fever, black-colored urine, and laboratory findings suggesting intravascular hemolysis. She was treated with supportive care, including the transfusion of 10 packs of red blood cells and the maintenance of fluid and electrolyte balance, and she gradually improved within two weeks. BWF is a rare but severe complication induced by severe falciparum malaria and/or the use of the arylamino alcohol group of antimalarial drugs. Thus, consideration of BWF is particularly important for a rapid and accurate diagnosis.

View full abstract

Sulfamethoxazloe-trimethoprim is one of the most frequently used antibiotics in the treatment of Nocardia infection. However, in vitro studies have shown an increase in sulfonamide resistance among Nocardia species. Here, we present a case with a brain abscess caused by Nocardia farcinica in which the test results for drug susceptibility to sulfonamide conflicted with the actual clinical course. A 74-year-old woman with autoimmune hepatitis who has being treated with oral prednisolone (16mg/day) was admitted because of headaches and fever. A CT scan and MRI revealed a brain abscess that had ruptured into the lateral ventricle. She was empirically treated with antibiotics, but her condition did not resolve. Therefore, the abscess was drained surgically. GramandKinyoun stains for pus revealed a modified acid-fast branching filamentous bacterium consistent with Nocardia species. The pathogen was identified as Nocardia farcinica based on its 16S rRNA sequence. Consequently, the patient was treated with sulfamethoxazole -trimethoprim and amikacin. However, susceptibility testing (broth microdilution method) showed that the strain was completely resistant to sulfamethoxazole-trimethoprim. We therefore changed the therapeutic regimen to imipenem-cilastatin and amikacin, but her symptoms worsened and the treatment was thought to have failed. She was then re-treated with sulfamethoxazole- trimethoprim, and her symptoms resolved. Some reports have suggested that interpreting the results of Nocardia susceptibility testing may be difficult especially the susceptibility of Nocardia to sulfamethoxazole-trimethoprim. The present case suggests a confliction between susceptibility testing and the clinical course of a patient with Nocardia infection.

View full abstract

Bacteremic urinary tract infection (UTI) caused by Stenotrophomonas maltophilia rarely occurs in pediatric patients. We report a case of bacteremic UTI caused by S. maltophilia in an 8-month-old boy with a congenital ureteropelvic junction obstruction on the left side. The patient was brought to our hospital with a chief complaint of fever. He had undergone a nephrostomy tube insertion 4 months previously, and the tube had been removed 2 weeks before presentation at our hospital. He had a white blood cell count of 6,100/μL and a serum C-reactive protein level of 4.51 mg/dL. A microscopic urinalysis and Gram stain showed numerous Gram-negative bacilli and many leukocytes, and an ultrasonography showed grade 4 hydronephrosis of the left kidney. Based on these findings, we diagnosed the infant as having a complex UTI and started the intravenous administration of piperacillin/tazobactam. After 2 days, a urine culture showed Gram-negative bacilli (10⁷CFU/mL). Gram-negative bacilli were also cultured from two blood samples that were taken from different vessels at the time of admission. The Gram-negative bacilli were identified as S. maltophilia via the automated bacterial identification system. The patient recovered after a 2-week intravenous piperacillin/tazobactam treatment and subsequent oral treatment with trimethoprim-sulfamethoxazole. Since medical devices are susceptible to contamination with S. maltophilia, we suspect that the nephrostomy tube was the most likely source of infection.

View full abstract

A 51-year-old man presented at the emergency department with a one-day history of fever, altered mental status, slurred speech, worsening gait instability, nausea, vomiting, and diarrhea. The patient did not have a history of alcoholism or drug abuse. On physical examination, crackles were heard over the right lower lobe. Neurological findings revealed ataxic gait, dysarthria and bilateral dysmetria upon finger-nose testing. The results of laboratory tests revealed leukocytosis, renal failure, and hyponatremia. Chest radiography and lung computed tomography (CT) revealed right lower lobe infiltrates with air bronchograms. The result of a urinary Legionella antigen test was positive. The results of brain CT and cerebrospinal fluid (CSF) analyses did not reveal any signs of infection, but brain magnetic resonance imaging (MRI) revealed a corpus callosum lesion upon admission. The patientʼs symptoms began to resolve after the administration of intravenous levofloxacin. A subsequent brain MRI examination performed 9 days after admission showed the complete resolution of the lesion. He was discharged 11 days after admission without any neurological sequelae. He was finally diagnosed as having clinically mild encephalitis/ encephalopathy with a reversible splenial lesion (MERS).

View full abstract