Naohisa Kawamura

Emergence of Macrolide-Resistant Mycoplasma pneumoniae with a 23S rRNA Gene Mutation

ABSTRACT A total of 195 Mycoplasma pneumoniae strains were isolated from 2,462 clinical specimens collected between April 2002 and March 2004 from pediatric outpatients with respiratory tract infections. Susceptibilities to six macrolide antibiotics (ML), telithromycin, minocycline, levofloxacin, and sitafloxacin were determined by the microdilution method using PPLO broth. A total of 183 M. pneumoniae isolates were susceptible to all agents and had excellent MIC90s in the following order: 0.00195 μg/ml for azithromycin and telithromycin, 0.0078 μg/ml for clarithromycin, 0.0156 μg/ml for erythromycin, 0.0625 μg/ml for sitafloxacin, 0.5 μg/ml for minocycline, and 1 μg/ml for levofloxacin. Notably, 12 ML-resistant M. pneumoniae strains were isolated from patients with pneumonia (10 strains) or acute bronchitis (2 strains). These strains showed resistance to ML with MICs of ≥1 μg/ml, except to rokitamycin. Transition mutations of A2063G or A2064G, which correspond to A2058 and A2059 in Escherichia coli, in domain V on the 23S rRNA gene in 11 ML-resistant strains were identified. By pulsed-field gel electrophoresis typing, these strains were classified into groups I and Vb, as described previously (A. Cousin-Allery, A. Charron, B. D. Barbeyrac, G. Fremy, J. S. Jensen, H. Renaudin, and C. Bebear, Epidemiol. Infect. 124:103-111, 2000). These findings suggest that excessive usage of MLs acts as a trigger to select mutations on the corresponding 23S rRNA gene with the resultant occurrence of ML-resistant M. pneumoniae. Monitoring ML susceptibilities for M. pneumoniae is necessary in the future.

A practical approach estimating etiologic agents using real-time PCR in pediatric inpatients with community-acquired pneumonia

To evaluate pathogens in pediatric inpatients with community-acquired pneumonia (CAP), an Acute Respiratory Diseases Study Group organized by ten Japanese medical institutions devised a rapid, reliable process based on real-time PCR results in nasopharyngeal swab samples plus admission blood test results. From April 2008 to April 2009, we enrolled 903 children with CAP based on chest radiographs and clinical findings who were hospitalized within 5xa0days of onset. Comprehensive real-time PCR was used to detect 6 bacteria and 11 respiratory viruses. The swab specimens also were used for bacterial cultures. After initial determination of presence or absence of viral and mycoplasmal infections, significant bacterial contributions were defined by bacterial identification, clinical efficacy of antimicrobial agent, and reference to blood test results. Children were stratified by age: below 1xa0year, 1xa0year, 2–5xa0years, or at least 6xa0years old. Among patients studied, 34.4xa0% were diagnosed with viral infection; 21.8xa0%, bacterial infection; 17.5xa0%, viral/bacterial co-infection; 5.9xa0%, mycoplasmal infection; 0.3xa0%, mycoplasmal/bacterial co-infection; and 1.7xa0%, viral/mycoplasmal co-infection. The remaining 18.4xa0% had unknown pathogens. Purely viral infection was suggested mainly in infants younger than 1xa0year; mycoplasmal infection typically occurred in children at least 6xa0years old. Our results suggest usefulness of real-time PCR for nasopharyngeal samples together with blood tests in estimating etiologic agents in clinical settings.

Pharmacokinetics of All-trans Retinoic Acid in Pediatric Patients with Leukemia

Since all‐trans retinoic acid (ATRA) induces complete remission in a high proportion of patients with acute promyelocytic leukemia (APL), and its effectiveness appears to be related to the plasma or serum level, a pharmacokinetic study of ATRA was undertaken in nine patients with various leukemias. After oral administration at a dose of 30 mg/m2, the time required to reach the peak plasma level of ATRA (20–1198 ng/ml) was between 120 and 240 min and the apparent plasma elimination half life was 21–51 min. In addition, 13‐cis retinoic acid was detected in the plasma of seven patients, indicating the occurrence of ATRA isomerization in vivo. ATRA therapy did not induce complete remission in all patients, even when high plasma levels were achieved. Among the six APL patients given ATRA therapy, one who failed to respond had a very low plasma ATRA level. These findings suggest that it may be useful to monitor plasma levels during oral ATRA therapy in order to achieve an appropriate treatment regimen.

Antioxidant enzymes and vitamins in Down's syndrome

Abstract Twenty-two children with Donws syndrome and 25 age-matched control children were examined to determine their levels of antioxidant enzymes and vitamins. Cu, Zn-superoxide dismutase (SOD), Mn-SOD, glutathione peroxidase (GSH-Px) and catalase were studied as antioxidant enzymes, while α-tocopherol, β-carotene, and retinol were studied as antioxidant vitamins. The Cu, Zn-SOD activity and immoreactive protein levels in plasma and red blood cells were higher in Downs syndrome children than in control children, while plasma Mn-SOD was lower in Downs syndrome children than in controls. Red cell GSH-Px and catalase activities were lower in Downs syndrome than in the controls, but the difference was not significant. There were also no significant differences in the α- and γ-tocopherol levels in plasma, platelets, mononuclear cells, polymorphonuclear cells, and buccal mucosal cells between the Downs syndrome children and the control children. Finally, no significant differences were observed in plasma β-carotene and retinol levels.

Effect of angiotensin-converting enzyme inhibitor on matrix metalloproteinase-9 activity in patients with Kawasaki disease.

BACKGROUNDnMatrix metalloproteinase (MMP)-9 is thought to be involved in coronary artery aneurysms (CAAs) in patients with Kawasaki disease (KD); however, MMP-9 inhibitors are not used clinically. This study investigated whether the angiotensin-converting enzyme (ACE) inhibitor captopril could inhibit serum MMP-9 activity using serum from KD patients in an in vitro experiment.nnnMETHODSnIn 7 KD patients, serum MMP-9 activity was measured using the MMP-9 assay kit 3 times: before and after intravenous immunoglobulin (IVIG) treatment, and during the convalescent phase. The effect of captopril on MMP-9 activity was also assessed using serum obtained before IVIG treatment.nnnRESULTSnSerum MMP-9 activity was significantly higher during the pre-treatment phase than during the post-treatment and convalescent phases. MMP-9 activity during the pre-treatment phase was dose-dependently inhibited by captopril, and the IC(50) for MMP-9 was 500nM. The potency of captopril for MMP-9 inhibition was comparable to that for ACE inhibition.nnnCONCLUSIONnACE inhibitor may be effective for preventing CAA formation in KD patients, especially IVIG non-responders.

Immunogenicity and safety of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) co-administered with DTPa vaccine in Japanese children: A randomized, controlled study

This phase III, randomized, open-label, multicenter study (NCT01027845) conducted in Japan assessed the immunogenicity, safety, and reactogenicity of 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV, given intramuscularly) co-administered with diphtheria-tetanus-acellular pertussis vaccine (DTPa, given subcutaneously). Infants (N=360 ) were randomized (2:1) to receive either PHiD-CV and DTPa (PHiD-CV group) or DTPa alone (control group) as 3-dose primary vaccination (3–4–5 months of age) and booster vaccination (17–19 months of age). Immune responses were measured before and one month after primary/booster vaccination and adverse events (AEs) were recorded. Post-primary immune responses were non-inferior to those in pivotal/efficacy European or Latin American pneumococcal protein D-conjugate vaccine studies. For each PHiD-CV serotype, at least 92.6% of infants post-primary vaccination and at least 97.7% of children post-booster had pneumococcal antibody concentrations ≥0.2 μg/ml, and at least 95.4% post-primary and at least 98.1% post-booster had opsonophagocytic activity (OPA) titers ≥8 . Geometric mean antibody concentrations and OPA titers (except OPA titer for 6B) were higher post-booster than post-priming for each serotype. All PHiD-CV-vaccinated children had anti-protein D antibody concentrations ≥100 EL.U/ml one month post-primary/booster vaccination and all were seroprotected/seropositive against each DTPa antigen. Redness and irritability were the most common solicited AEs in both groups. Incidences of unsolicited AEs were comparable between groups. Serious AEs were reported for 47 children (28 in PHiD-CV group); none were assessed as vaccine-related. In conclusion, PHiD-CV induced robust immune responses and was well tolerated when co-administered with DTPa in a 3-dose priming plus booster regimen to Japanese children.

Soluble interleukin-2 receptor level in serum of children with insulin-dependent diabetes mellitus compared with that in diseases with activated immune system

Abstract The serum level of soluble interleukin-2 receptor (sIL-2R) has been proposed as a clinical marker for various autoimmune diseases. Serum in patients with insulin-dependent diabetes mellitus (IDDM), as an organ-specific autoimmune disease, was investigated by sIL-2R assay. Although serum sIL-2R levels were very much higher in patients with acute lymphocytic leukemia and chronically or subchronically inflammatory diseases including Schoenlein-Henoch disease, juvenile rheumatoid arthritis (JRA), systemic lupus erythematosus (SLE), ulcerative colitis (UC) and mucocutaneous lymph node syndrome (MCLS), the level in IDDM children who were newly diagnosed (within 6 months after onset) was also moderately higher (628 ± 64 U/ml; P 1c level, or patient. ThesThese findings suggest that slowly progressing T-cell activation and an imbalanced cellular immune response exist in newly diagnosed IDDM children.