Naoto Rikitomi

A comparative clinical study of pneumonia by penicillin-resistant and -sensitive Streptococcus pneumoniae in a community hospital.

This study aimed to determine the clinical difference of pneumonia between penicillin‐resistant and penicillin‐sensitive Streptococcus pneumoniae.

The Effects of S‐Carboxymethylcysteine and N‐Acetylcysteine on the Adherence of Moraxella catarrhalis to Human Pharyngeal Epithelial Cells

We investigated the effects of two mucoregulating drugs, S‐carboxymethyleysteine (S‐CMC) and N‐acetylcysteine (NAC), on the attachment of Moraxella catarrhalis (M. catarrhalis) to pharyngeal epithelial cells. The attachment of M. catarrhalis decreased (3357%) significantly (P<0.01) in a dose‐dependent manner in cells treated with mucoregulating drugs as compared to the control. There was a significant (P< 0.01) decrease (35 45%) in the attachment of M. catarrhalis to pharyngeal cells after oral administration of S‐CMC. By electron microscopic observation, it was found that there was a fine, granular, electron‐dense, ruthenium red‐positive layer on the surface of pharyngeal epithelial cells; this layer was absent on cell surfaces treated with mucoregulating drugs. Possibly, this layer contained the portion of M. catarrhalis receptor which is responsible for the attachment of this bacteria to pharyngeal epithelial cells. From the above results, it may be concluded that one of the mechanisms of mucoregulating drugs to decrease the episode of respiratory infections in patients with chronic respiratory diseases is by inhibiting the attachment of bacteria to the upper respiratory tract.

Mechanism of adherence of Moraxella(Branhamella)catarrhalis.

We examined the mechanisms of adherence of Moraxella catarrhalis to nasopharyngeal epithelial cells. Fimbriae were detected by electron microscopy on most of the strains studied. A role of fimbriae in adherence was supported by the reduction in adherence by treatments denaturing the fimbriae or by antifimbrial antibodies. There was, however, no significant difference in adhesive capacity or hemagglutination between fimbriated and non-fimbriated strains. Furthermore, there was no correlation between hemagglutination and adherence. The possibility that receptor epitopes were provided by cell surface glycolipids was examined by thin-layer chromatography. Glycolipids from various sources, including nasopharyngeal cells were separated by thin layer chromatography plates and overlayed with bacteria. No binding was detected. The results suggest that lectin-glycolipid interactions do not explain the attachment of M. catarrhalis to epithelial cells.

Fimbriation, Hemagglutination and Adherence Properties of Fresh Clinical Isolates of Branhamella catarrhalis

This study investigated the fimbriation on 24 fresh clinical isolates of Branhamella catarrhalis by electron microscopy. All the strains were isolated from patients with respiratory infections. The Branhamella catarrhalis strains were classified into three groups according to the grade of fimbriation. Among these 24 strains the incidence of densely fimbriated, moderately fimbriated and sparsely fimbriated isolates were 12 (50%), 7 (29%) and 5 (21%), respectively. After five‐times serial subculture on Brain Heart Infusion agar, the average number of fimbriae per bacteria was decreased from 174 to 114 in the densely fimbriated strain and from 48 to 10 in the moderately fimbriated strain. Moreover, 20% of the population became non‐fimbriated in moderately fimbriated strain after the serial subculture. In strains with higher hemagglutination titer the number of fimbriae was significantly (P<0.04) more than in strains with lower hemagglutination titer.

Possible Presence of a Capsule in Branhamella catarrhalis

Clinical isolates of Branhamella catarrhalis from patients with respiratory infections were used in this study. Electron microscopic observation after treating Branhamella catarrhalis with immune serum and ruthenium red revealed the capsule. In the phagocytosis test, most organisms were not ingested by human polymorphonuclear neutrophils in the presence of normal rabbit serum (NRS), while organisms were primarily cell associated and apparently ingested in the presence of immunized rabbit serum (IRS). The capsule may be one of the virulence factors in this bacteria. This study demonstrates the possible presence of a capsule in Branhamella catarrhalis.

Relationship between depression in patients with COPD and the percent of predicted FEV(1), BODE index, and health-related quality of life.

BACKGROUND: We investigated the prevalence of depression among patients with COPD treated in long-term in-patient rehabilitation facilities, using the Center for Epidemiologic Studies Depression scale (CES-D). Furthermore, the relationship between the severity of air-flow obstruction (the percent of predicted FEV1), BODE (body mass index, degree of air-flow obstruction, dyspnea, exercise capacity) index, health-related quality of life (St Georges Respiratory Questionnaire [SGRQ]), and depression were investigated. METHODS: We recruited 74 in-patients (64 males, 10 females) with COPD. The mean age of the subjects was 72.7 years (range 52–85 y). Subjects completed the CES-D, and measurements were made of pulmonary function, body mass index, Modified Medical Research Council dyspnea scale, 6-min walk test (6MWT), and SGRQ. RESULTS: Depression was evident in 48.6% (n = 36) of the subjects. A weak correlation was found between the CES-D scores and the percent of predicted FEV1. The prevalence of depression showed a significant association with BODE stage. Scores for the SGRQ activity and impacts domains, and total SGRQ score were significantly worse in the subjects who were depressed. CONCLUSIONS: We found a high prevalence of depression among patients with stable COPD treated in long-term in-patient rehabilitation facilities. Depression among these patients, as measured by the CES-D, was associated with greater impairment in respiratory function and with poorer Modified Medical Research Council dyspnea scale and SGRQ scores. The prevalence of depression increased with BODE stage.

The Role of MRSA (Methicillin-Resistant Staphylococcus aureus) Adherence and Colonization in the Upper Respiratory Tract of Geriatric Patients in Nosocomial Pulmonary Infections

The mechanism of nosocomial respiratory infections caused by MRSA (methicillin‐resistant Staphylococcus aureus) in geriatric patients was investigated. Seriously ill patients (SIP) undergoing naso‐gastric tube feeding or intravenous hyperalimentation and moderately ill patients (MIP) who were orally fed, were examined for their colonization and infection by Staphylococcus aureus (S. aureus) in the respiratory tract. Colonization of MRSA in the upper respiratory tract in SIP was from six to ten times higher than that in MIP and was associated with a high incidence of MRSA pulmonary infections. In vitro S. aureus adherence to nasal or oropharyngeal cells demonstrated that bacteria binding to nasal cells was higher, which probably can be interpreted as an elevated occurrence of S. aureus colonization in the nasal cavity than in the throat. The binding activity of MRSA was not superior to that of MSSA (methicillin‐sensitive S. aureus). Though MRSA binding to the nasal cells from SIP was not higher than those from MIP, MRSA colonization in the upper respiratory tract was more frequently seen in SIP (P < 0.01). A higher incidence of total infectious episodes (P < 0.02‐0.001) and more frequent use of antibiotics (P < 0.02‐0.001), which were potent against MSSA might be the basis for selection of MRSA in these patients. In fact, the rate of MRSA colonization on the skin (pressure sores) was also higher in SIP (P < 0.01). A low nutritional state in SIP (P < 0.01‐0.02) might also be associated with MRSA colonization. The present results indicate that the high frequency of infections, antibiotic administration, MRSA skin colonization and low nutritional condition, are enhancing factors of MRSA acquisition in the respiratory tract for SIP undergoing artificial feeding, in a geriatric hospital.

Electron microscopic observation of Branhamella catarrhalis

The hemagglutination (HA) test was done on 85 strains of Branhamella catarrhalis, isolated from sputum of patients with respiratory infections; 53% were HA positive strains. Three HA positive and three HA negative strains were selected and were observed under the electron microscope. The bacterial cell wall appeared to be lobulated and its total thickness was about 38 nm. The nuclear region consisted of whorls or fibrils and dense bodies. Five strains were fimbriated and one strain was nonfimbriated. The size of fimbriae was about 68 nm in length and 4.5 nm in width. The fimbriae of Branhamella catarrhalis were densely arranged and peritrichous in distribution. There was no change of fimbriation between broth and agar cultures.

Rapid Increase of Pneumococcal Resistance to β-Lactam and Other Antibiotics in Isolates from the Respiratory Tract (Nagasaki, Japan: 1975–1994)

The susceptibility of 101 pneumococcal isolates from the respiratory tract during 1991–1994 was examined and compared with the susceptibility of isolates over the period of 1975–1990. A rapid increase of resistance was seen not only to penicillin but also other antimicrobial agents. During 1991–1994, 38% of all the isolates were resistant to penicillin. The rates of resistance during this period were 16–23% for three newer cephalosporins, 18% for imipenem, 69% for tetracycline, 31% for erythromycin, 20% for chloramphenicol and 9% for clindamycin. The use of antibiotics within one month prior to pneumococcal isolation was correlated with penicillin resistance (P < 0.05). Serotyping of the isolates by antiserum revealed differences in predominant types between penicillin‐resistant (19F, 23F, 4) and ‐susceptible isolates (15, 4, 11A). Our data suggests that anti‐pneumococcal antibiotics should be carefully chosen on the basis of susceptibility tests.

Attachment of Nontypable Haemophilus influenzae to Human Pharyngeal Epithelial Cells Mediated by a Ganglioside Receptor

Nontypable Haemophilus influenzae (NTHI) is one of the major pathogens of human respiratory infections and has the ability to attach to pharyngeal epithelial cells. We characterized the epithelial cell receptor to which NTHI bind. Neuraminidase pretreatment of pharyngeal epithelial cells resulted in a significant decrease in NTHI attachment, suggesting sialic acid as an important component of the receptor. The attachment was not decreased in NTHI pretreated with 1,000 μg/ml of fucose, N‐acetyl‐neuraminic acid, N‐acetyl‐glucosamine, N‐acetyl‐galactosamine, acetyl‐salicylic acid and colominic acid. Only treatment with gangliosides D1a, D1b and D2 at a concentration of 12.5 μg/ml significantly decreased the attachment. On the other hand, treatment with gangliosides M1, M2, M3, D3, T1b and asialoganglioside M1 did not decrease the attachment of NTHI. Only ganglioside D2 inhibited the attachment significantly at a concentration of 12.5 ng/ml. Other isolates of NTHI showed a decrease in attachment after treatment with ganglioside D2. Treatment of cells with anti‐human GD2 monoclonal antibody also decreased the attachment of NTHI in a dose‐dependent manner. This study indicates that sialic acid glycoconjugate, GD2, is one of the receptors of NTHI on human pharyngeal epithelial cells.