Shinichi Fujita

Increasing Prevalence of Ampicillin- Resistant, Non-Beta-Lactamase-Producing Strains of Haemophilus influenzae in Children in Japan

Among Haemophilus influenzae isolated from children with respiratory tract infections, the evolution of ampicillin resistance was investigated during 1996 and 1997 in Japan. β-Lactamase production was assessed and minimum inhibitory concentrations (MICs) of eight antimicrobial agents were determined using a broth microdilution method in Mueller-Hinton-lysed horse blood medium. Of 74 H. influenzae, 11 strains (14.9%) produce β-lactamase and were thus highly resistant to ampicillin (MIC of >4.0 µg/ ml). In addition, moderate resistance to ampicillin, defined as an MIC of ≧1.0 µg/ml, was noted in 44.4% of all β-lactamase-negative isolates. These β-lactamase-negative ampicillin-resistant (BLNAR) organisms were resistant to other cephalosporins such as cefpodoxime and cefdinir, while β-lactamase-producing strains were susceptible to them. Cefditoren, cefteram, and minocycline were active against all strains studied, whereas cefaclor and clarithromycin were inactive against all H. influenzae isolates in this study. Results indicate that BLNAR strains have emerged among children with respiratory tract infections in Japan.

Antimicrobial Susceptibility of Respiratory Tract Pathogens in Japan During PROTEKT Years 1–5 (1999–2004)

Susceptibility to a range of antimicrobial agents was determined among isolates of Streptococcus pneumoniae, Streptococcus pyogenes, and Haemophilus influenzae collected in 12 centers throughout Japan during years 1-5 (the respiratory seasons of 1999-2004) of the longitudinal Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin study. The most frequent source of isolates of S. pneumoniae was from patients with community-acquired pneumonia (CAP) (25.3%). Reduced susceptibility to penicillin or erythromycin resistance was common among S. pneumoniae isolates (30.9-44.5% and 77.2-81.9%, respectively). The macrolide MIC(50) for S. pneumoniae was >or=128 microg/ml (azithromycin and erythromycin) and >or=64 microg/ml (clarithromycin). The erm(B) genotype accounted for the most erythromycin-resistant isolates in each study year. H. influenzae isolates were most commonly derived from patients with CAP (26.2%). The proportion of H. influenzae isolates that were beta-lactamase positive ranged between 4.3% and 9.7%. The prevalence of beta-lactamase-negative ampicillin-resistant isolates increased from 0.4% to 2.6% between years 1 and 4 then to 19.7% in year 5. S. pyogenes isolates were highly susceptible to most antimicrobial agents except macrolides and tetracycline. Telithromycin was highly active against all three pathogens examined throughout the study.

Occurrence of the Fimbria Gene hifA in Clinical Isolates of Nonencapsulated Haemophilus influenzae

The adherence of Haemophilus influenzae to epithelial cells plays a crucial role in infections. However, little is known about the occurrence of fimbriae. In this study, we examined the distribution of the fimbria gene (hifA) by PCR among 167 H. influenzae strains isolated from patients with respiratory infections. Almost all (163; 98%) of the isolates were nonencapsulated strains. The carriage rate of hifA by the nonencapsulated strains was 18.4%. Electron microscopy showed that fimbriae were abundantly present on the cell surface of hifA‐positive strains tested. Only four (2.4%) isolates were encapsulated, all of which were type b and did not possess hifA. The present work suggests that fimbriae may play a considerable role as adhesins in nonencapsulated H. influenzae strains.

Internal Transcribed Spacer (ITS)-PCR Identification of MRSA

Polymerase chain reaction (PCR) analysis of the 16S-23S rRNA gene internal transcribed spacer (ITS) followed by microchip gel electrophoresis was useful for identification of staphylococci and for strain delineation of Staphylococcus aureus. In the study presented in this chapter, 74 ITS patterns were demonstrated among 1,188 isolated colonies of S. aureus: 55 patterns for methicillin-susceptible S. aureus (MSSA), 4 patterns for methicillin-resistant S. aureus (MRSA), and 15 patterns for both MSSA and MRSA, highlighting the inability of ITS pattern analysis to differentiate the MSSA and MRSA strains. To overcome this problem, simultaneous PCR amplification of the ITS region and mecA gene was applied to isolated colonies of staphylococcus species and positive-testing blood culture bottles.

Latex agglutination text for o serogrouping of Klebsiella species

The importance of a number of Klebsiella species as a cause of nosocomial infec tionhas been stressed in a number of reports (6, 7). Various typing systems such as capsular serotyping (10, 11), biotyping (10), and klebocin typing (2) alone or in combination have been employed to trace the actual routes of Klebsiella infection. For epidemiological studies, the most useful method has been capsular serotyping

TWO CASES OF ERYTHEMA NODOSUM SECONDARY TO STREPTOCOCCAL INFECTION

溶連菌感染症に続発したと考えられる結節性紅斑(EN)の2症例を経験した.両症例ともENは上気道炎に罹患後1～2週間に出現し,紅斑の出現とほぼ一致してantistreptolysin O値とantistreptokinase値の上昇がみられた.皮下結節の組織学的検索でもENの定型的組織像を呈していた.症例2では入院時に行なつた咽頭培養にてA群溶連菌8型が純培養状に分離された. PHAとstreptolysin O (SLO)の添加によるリンパ球幼若化反応を3H-thymidineのとりこみで,健康人を対照にして検討したところ, PHAによるstimulation index (SI)はENでは健康人よりも約50%低下していたが, SLOの場合にはEN症例で健康人よりもSIで1.5～3倍と高値を示したため,溶連菌感染症に続発したEN症例では, SLOに対する特異的細胞性免疫が成立していることが予想された.本症の治療はペニシリン剤と抗炎鎮痛剤の併用が効果的で,とくに重症例ではステロイドホルモンの投与が著効を呈すると考えられた.