Noboru Yamanaka

Formation of biofilm by Haemophilus influenzae isolated from pediatric intractable otitis media

OBJECTIVESnThe aims of this study are to evaluate biofilm formation by nontypeable Haemophilus influenzae (NTHi) isolated from children with acute otitis media (AOM) and its relation with clinical outcome of the disease.nnnMETHODSnBiofilm formations by NTHi clinical isolates from pediatric AOM patients were evaluated by a crystal violet microtiter plate and a 98 well pin-replicator assay with a confocal laser scanning microscopy (CLSM). Optical density values of clinical isolates were compared with a positive control and the ratio of clinical isolates to a positive control was defined as biofilm formation index (BFI).nnnRESULTSn84.3% clinical isolates of NTHi were biofilm forming strains (BFI> or =0.4). The BFI represented the levels of biofilm formation and adherence on the surface. The identical strains isolated from both middle ear fluids (MEFs) and nasopharynx showed biofilm formation at the same level. The prevalence of biofilm forming isolates was significantly higher among the susceptible strains than resistant strains. The level of biofilm formation of NTHi isolated from AOM cases who was not improved by amoxicillin (AMPC) was significantly higher than that of NTHi isolated from AOM cases who was improved by AMPC.nnnCONCLUSIONnWe clearly showed the biofilm formation of clinical NTHi isolates from AOM children. In addition, the biofilm formed by NTHi would play an important role in persistent or intractable clinical course of AOM as a result of lowered treatment efficacy of antibiotics.

Nontypeable Haemophilus influenzae isolated from intractable acute otitis media internalized into cultured human epithelial cells.

OBJECTIVESnThe aim of this study is to examine the internalization of nontypeable Haemophilus influenzae (NTHi) into human epithelial cells.nnnMETHODSnBactericidal assay was applied to examine the effects of antibiotics against cell-adherent NTHi using HEp-2 cells. A trans-well chamber assay was applied to examine the internalization and penetration of NTHi using Detroit562 cells.nnnRESULTSnThe adherence of NTHi to HEp-2 cells was noted after 2h of incubation. Azithromycin had a strong bactericidal effect against both cell-associated and non-adherent NTHi, while ceftriaxone did not show bactericidal effects on NTHi adhered to the HEp-2 cells. Three (60.0%) out of five NTHi isolates from the nasopharynx of children with intractable acute otitis media (AOM) internalized into and subsequently penetrated through the epithelial cells at various degrees. Azithromycin had a strong bactericidal effect against the cell-internalized NTHi, while ceftriaxone was bactericidal only against extracellular NTHi.nnnCONCLUSIONnThe potential of NTHi as the intracellular pathogen may contribute to the persistent existence of this pathogen that result in the prolonged and intractable clinical course of AOM. Azithromycin may be a therapeutically significant antibiotic for patients with prolonged respiratory tract infections due to NTHi.

Clinical and microbiological impact of human bocavirus on children with acute otitis media

Human Bocavirus (HBoV) as a newly discovered parvovirus has been commonly detected in respiratory tract infections. However, its role in acute otitis media (AOM) has not been well studied. We examined HBoV in Japanese children with AOM and evaluated the virus prevalence together with clinical manifestations and bacterial findings. Overall, 222 nasopharyngeal swabs and 176 middle ear fluids (MEF) samples were collected from 222 children with AOM (median age, 19xa0months) between May 2006 and April 2007. HBoV detection was performed by PCR and bacterial isolation by standard culture methods. HBoV was found in the nasopharyngeal aspirates of 14 children (6.3%) and in the MEF of six children (2.7%). When HBoV detection results were evaluated with clinical characteristics of children, resolution time of AOM was significantly longer (p=0.04), and rate of fever symptom was also higher in HBoV-positive group (p=0.04). Furthermore, we found positive correlation between detection of HBoV and Streptococcus pneumoniae in the MEF (p=0.004). Nevertheless, nasopharyngeal proportion of S. pneumoniae was similar between virus positive and negative groups. Furthermore, S. pneumoniae was detected as a single pathogen in all MEF of HBoV-positive cases but one, while it presents mixed with other pathogenic bacteria in nasopharynx. In conclusion, HBoV may worsen the clinical symptoms and prolong the clinical outcome of AOM in pediatric population. Finally, HBoV may prime the secondary bacterial infection in the middle ear in favor of S. pneumoniae.

Haemophilus influenzae and Haemophilus haemolyticus in tonsillar cultures of adults with acute pharyngotonsillitis

OBJECTIVEnThe aim of this study was to evaluate the clinical implication of Haemophilus haemolyticus, one of the closest relative of Haemophilus influenzae, on acute pharyngotonsillitis.nnnMETHODSnWe applied polymerase chain reaction (PCR) for 16S ribosomal DNA (rDNA) and IgA protease gene (iga) to distinguish H. haemolyticus and H. influenzae.nnnRESULTSnAmong the 199 Haemophilus spp. isolated from 214 patients with acute pharyngotonsillitis, 52 (24.3%) H. influenzae strains and 23 (10.7%) H. haemolyticus strains were identified by polymerase chain reaction (PCR) for 16S rDNA and IgA protease gene (iga). All H. haemolyticus strains showed hemolysis on horse blood agar and there were no other Haemophilus spp., nonhemolytic H. haemolyticus and H. influenzae variant strains that had absent iga gene. H. hemolyticus showed close genetic relationship with H. influenzae evaluated by pulsed field gel electrophoresis (PFGE). The cases of acute pharyngotonsillitis showing WBC=7000/mm(3) or CRP=8 mg/dl were frequently found among cases with H. influenzae rather than cases with H. haemolyticus.nnnCONCLUSIONnH. haemolyticus is a pharyngeal commensal that is isolated frequently from adults with acute pharyngotonsillitis.

Maternal Immunization with Pneumococcal Surface Protein A Protects against Pneumococcal Infections among Derived Offspring

Pathogen-specific antibody plays an important role in protection against pneumococcal carriage and infections. However, neonates and infants exhibit impaired innate and adaptive immune responses, which result in their high susceptibility to pneumococci. To protect neonates and infants against pneumococcal infection it is important to elicit specific protective immune responses at very young ages. In this study, we investigated the protective immunity against pneumococcal carriage, pneumonia, and sepsis induced by maternal immunization with pneumococcal surface protein A (PspA). Mother mice were intranasally immunized with recombinant PspA (rPspA) and cholera toxin B subunit (CTB) prior to being mated. Anti-PspA specific IgG, predominantly IgG1, was present at a high level in the serum and milk of immunized mothers and in the sera of their pups. The pneumococcal densities in washed nasal tissues and in lung homogenate were significantly reduced in pups delivered from and/or breast-fed by PspA-immunized mothers. Survival after fatal systemic infections with various types of pneumococci was significantly extended in the pups, which had received anti-PspA antibody via the placenta or through their milk. The current findings strongly suggest that maternal immunization with PspA is an attractive strategy against pneumococcal infections during early childhood. (191 words)

Evaluation of a rapid immunochromatographic ODK-0901 test for detection of pneumococcal antigen in middle ear fluids and nasopharyngeal secretions.

Since the incidence of penicillin-resistant Streptococcus pneumoniae has been increasing at an astonishing rate throughout the world, the need for accurate and rapid identification of pneumococci has become increasingly important to determine the appropriate antimicrobial treatment. We have evaluated an immunochromatographic test (ODK-0901) that detects pneumococcal antigens using 264 middle ear fluids (MEFs) and 268 nasopharyngeal secretions (NPSs). A sample was defined to contain S. pneumoniae when optochin and bile sensitive alpha hemolytic streptococcal colonies were isolated by culture. The sensitivity and specificity of the ODK-0901 test were 81.4% and 80.5%, respectively, for MEFs from patients with acute otitis media (AOM). In addition, the sensitivity and specificity were 75.2% and 88.8%, respectively, for NPSs from patients with acute rhinosinusitis. The ODK-0901 test may provide a rapid and highly sensitive evaluation of the presence of S. pneumoniae and thus may be a promising method of identifying pneumococci in MEFs and NPSs.

Distribution of fibronectin-binding protein genes ( prtF1 and prtF2 ) and streptococcal pyrogenic exotoxin genes ( spe ) among Streptococcus pyogenes in Japan

Two hundred and seventy-two strains of Streptococcus pyogenes isolated from patients with invasive and noninvasive infections in Japan were evaluated for the prevalence of fibronectin-binding protein genes (prtF1 and prtF2). The possible associations of the genes with streptococcal pyrogenic exotoxin genes, macrolide resistance genes, and emm types were also evaluated. Overall, about 50% of S. pyogenes isolates carried fibronectin-binding protein genes. The prevalence of the prtF1 gene was significantly higher among isolates from noninvasive infections (71.4%) than among isolates from invasive infections (30.8%; P = 0.0037). Strains possessing both the prtF1 and prtF2 genes were more likely to be isolates from noninvasive infections than isolates from invasive infections (50.6% vs 15.4%; P = 0.019). S. pyogenes isolates with streptococcus pyrogenic exotoxin genes (speA and speZ) were more common among isolates without fibronectin-binding protein genes. The speC gene was more frequently identified among isolates with fibronectin-binding protein genes (P = 0.05). Strains belonging to emm75 or emm12 types more frequently harbored macrolide resistance genes than other emm types (P = 0.0094 and P = 0.043, respectively). Strains carrying more than one repeat at the RD2 region of the prtF1 gene and the FBRD region of the prtF2 gene were more prevalent among strains with macrolide resistance genes than among strains negative for macrolide resistance genes. These genes (i.e., the prtF1, prtF2, and spe genes) may enable host-bacteria interaction, and internalization in the host cell, but may not enable infection complications such as invasive diseases.

Pathogenic role of tonsillar lymphocytes in associated with HSP60/65 in Pustulosis palmaris et plantaris.

OBJECTIVEnWe aimed to define role of tonsillar lymphocytes (TL) and immune cross-reactivity between bacterial-HSP65 and human-HSP60 in Pustulosis palmaris et plantaris (PPP), an intractable chronic disease characterized with pustules and cornification of palms and soles.nnnMETHODSnTwo sets of crossover trials were designed by employing SCID mice model. In the first trial, mice were transplanted with tonsillar lymphocytes and skin-grafts from PPP patients (TL group). In the second trial, mice were transplanted with tonsillar lymphocytes from PPP patients and injected with recombinant human HSP60. Control groups were designed for each step. Comparisons were performed for immunologic analyses including infiltration of CD4+ lymphocytes in skin-grafts by immunostaining, and levels of anti-HSP65-IgG and cytokines in mice sera by enzyme-linked immunosorbent assay (ELISA).nnnRESULTSnIn TL group, infiltration of CD4+ lymphocytes in skin-grafts were significantly higher than mice transplanted with blood lymphocytes (p<0.05), while anti-HSP65-IgG levels in sera showed non-significant tendency to increase in the TL group. CD4+ cells and anti-HSP65-IgG levels were also well-correlated with each other in TL group (p<0.01). Besides, anti-HSP65-IgG levels were significantly correlated with cytokine levels (IL-6, IFN-gamma) in mice sera (p<0.01). We found strong expression of HSP60 in PPP lesions. Finally, HSP60-stimulation in mice transplanted with TL from PPP patients induced significantly higher anti-HSP65-IgG levels in serum compared to control groups including mice without HSP60-stimulation or peripheral blood lymphocytes-transplanted mice or transplanted with TL from control patients (p<0.05).nnnCONCLUSIONnOur results indicate the pathogenic role of TL and immune cross-reaction between human-HSP60 and bacterial-HSP65 in PPP.

Loss of erythromycin resistance genes from strains of Streptococcus pyogenes that have developed resistance to levofloxacin.

In the past 2 to 3 decades, erythromycin resistance in Streptococcus pyogenes has been decreasing, whereas fluoroquinolone resistance (or reduction in its susceptibility) has been reported often. Although a shift of M-type prevalence and decreased pressure from macrolides have been suggested for the decrease in erythromycin resistance, we hypothesized that this might also be a result of increased antimicrobial pressure from fluoroquinolone use. Levofloxacin resistance for 4 erythromycin-resistant parent strains was induced in vitro. Their mutants became highly resistant to the fluoroquinolones but lost their erythromycin resistance trait. Erythromycin resistance was fully restored by transconjugation with respective parent strains with either mefA- or ermTR-mediated mechanisms.

Moving towards a new era in the research of tonsils and mucosal barriers.

The palatine and nasopharyngeal tonsils (adenoids) are lymphoepithelial tissues located in strategic anatomical areas of the oral pharynx and nasopharynx. These immunocompetent tissues represent the first line of defense against ingested or inhaled foreign proteins such as bacteria, viruses, or food antigens. Accompanying the advances being made in the field of medicine today, the role of the tonsils in immunocompetence is becoming extremely important. Upper respiratory tract infections such as acute otitis media, acute rhinosinusitis and acute pharyngo-tonsillitis are diseases that occur with extremely high frequency, and the antimicrobial agents used to treat these diseases account for a large proportion of health care costs. The increasingly refractory nature of upper respiratory tract infections caused by drug-resistant bacteria has become a major worldwide concern. The elucidation of the immune functions of the tonsils and mucosal membranes of the upper respiratory tract is considered to have important significance. The tonsils are also considered to play an important role as one of the causes of sleep apnea syndrome, and have been reported to be intimately involved in the manifestation of IgA nephropathy and palmoplantar pustulosis, a kind of skin disorder. Interest has continued to grow in this symposium with each session ever since it was first held in Kyoto, Japan in 1987. Since then, the symposium has been held every 3-4 years; in Pavia in 1991, in Sapporo in 1995, in Ghent in 1999, in Wakayama in 2003, and in Siena in 2006. Since the 5th symposium in Wakayama, the topics were extended to mucosal barriers of upper airways including the mucosal immune system, innate immunity, and mucosal vaccine. Recent fine technologies and information on molecular biological approaches for upper airways will continue to advance our understanding of epidemiology, etiology, pathogenesis, diagnosis and management of tonsil-related disorders and various upper respiratory tract infections such as otitis media and rhinosinusitis. Moreover, in the era of drug-resistant microbes, we should exert more effort to develop powerful and effective mucosal vaccines against pathogens in upper airways.