We determind antimicrobial susceptibilities of 23 strains of Legionella spp. clinically isolated in Japan, between September 1994 through November 1999 by using Etest. The MICs of all isolates against macrorides, fluoroquinorones and rifampicin showed 1μg/ml or less. Especially rifampicin showed the most potent activity, of which the MICs of all isolates showed 0.064μg/ml or less. Although we could not find resistant strains against any antibiotics tested in this study, we think it is important to follow up the susceptibilities of clinical isolates of Legionella.

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Susceptibility testing of mupirocin (MUP) was performed by an agar dilution method according to the National Committee for Clinical Laboratory Standard (NCCLS) to detect the MUP resistance. A total of 434 isolates of methicillin-resistant staphylococci were examined and all of 205 isolates of methicillin-resistant Staphylococcus aureus (MRSA) from 43 hospitals nationwide in 1993 were sensitive to MUP. However, MUP resistance emerged among 228 isolates [185 isolates (88 cases) of MRSA and 43 isolates (28 cases) of methicillin-resistant coagulase negative staphylococci (MR-CNS)] from nasal swabs of patients with MUP treatment between Sep 1996 and Feb 2000 in the Nagoya University Hospital. The high-level MUP resistance (MIC≥512μg/mL) was isolated from two patients, one isolate of MRSA and four of S. hominis, respectively. Low-level MUP resistance (MIC 8-128μg/mL) was isolated from three patients, 11 isolates of MRSA, one of S. chromogenes and five of S. epidermidis, respectively. The mupA which encodes the MUP resistant isoleucyl-tRNA synthetase (IRS) were investigated by PCR in these MUP resistant isolates. The mupA was detected only in high-level MUP resistant S. hominis, but not detected in high-level MUP resistant MRSA and low-level MUP resistant isolates. We also investigated the characteristics of the patients with MUP resistance. All of MUP resistant staphylococci were isolated after initiation of MUP treatment. Four patients with MUP resistant MRSA and low-level MUP resistant MR-CNS had MRSA infectious disease and MUP resistant strains were successfully eradicated with vancomycin treatment in two patients. MUP high-level resistant S. hominis, has emerged after MUP treatment for eradication of MRSA. Clinical guidelines for the prudent use of MUP should be generally adopted with careful monitoring of emergence of MUP resistance.

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We studied 2, 176 nasopharyngeal swabs obtained from 1, 891 children on admission to the pediatric ward at Asahikawa Kosei Hospital from January 1997 to December 1998, and compared the results with the same study from January 1992 to December 1993. Fifty strains of Methicillin-resistant Staphylococcus aureus (MRSA) were isolated from 46 patients. The ages of these patients ranged from 7 days to 17 years and 24 patients were younger than 1 year. Six patients were diagnosed as MRSA infection; acute otitis media in 3, osteomyelitis and bacteremia in 1, staphylococcal scalded skin syndrome in 1, and inflammation in umbilical region in 1. The ratio of MRSA positive to the total specimens significantly increased from 1.25% in 1992-1993 to 2.30% in 1997-1998 (p=0.011). The ratio of MRSA positive to the total S. aureus positive specimens significantly increased from 10.7% in 1992 1993 to 20.3% in 1997-1998 (p=0.003). These findings demonstrated that prevalence of MRSA carriers among children is increasing.

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Immune complex containing alginate and antialginate antibodies plays an important role in the disease-progress of chronic airway infection with mucoid-alginate producing strains. For the purpose of clarifying the immune-pathogenic influence of the alginate induced immune complex (alg-IC) on inflammatory cells in bronchoalveolar lavage fluid (BALF), an experimental study was performed.
The alginate immunized mice were injected through the trachea with alg-IC extracted from the immunized mouse serum in advance, and the changes in BALF-cells, such as macrophage, neutrophil, lymphocyte, CD16/32 positive neutrophil, CD4+lymphocyte, CD4+CD45+lymphycyte, CD8+ lymphocyte, CD8+CD11b-lymphocyte were investigated along with the passage of time as compared with those of the non-immunized mice.
1) On the 2nd day after intratracheal injection, the time which was chosen as an acute phase, the total count of macrophages, neutrophils, lymphocytes were increased in both groups. However CD16/32 positive neutrophil (with the expression of Fc-γ recepter on it) was significantly decreased in the immunized group.
2) On the 5th day being chosen as the resolving phase of acute inflammation, the number of the increased inflammatory cells tended to recover to the base line value in both groups. But the continuous decrease in CD16/32 positive cell and the significant increase in CD4+CD45+lymphocytes were found in only the immunized group.
3) On the 16th day being chosen as the beginning of the chronic phase, all inflammatory cells investigated in the non-immunized group recovered to the base line level. In the immunized group, however, significantly higher values of neutrophil-count still remained, in spite of the decrease in CD 16/32 positive neutrophils. Also, CD4+CD45+, CD8+, CD8+CD11b-lymphocytes were significantly at a higher level.
4) Histological findings in the lung tissue was supported the above findings.
5) From the above, in the alginate immunized group, the scavenging function of neutrophils for the alg-IC deposited in lung tissue would be suppressed resulting from the decrease in CD16/32 positive neutrophils, in sipte of the increase in total count of neutrophils.

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Pathogenic mechanisms of mycoplasmal pneumonia is not fully understood at present though some kind of cell-mediated hypersensitivity is closely related to its mechanisms. Though eosinophilia in peripheral blood are sometimes revealed in patient with mycoplasmal pneumonia, it is not unclear whether eosinophils related to its pathogenesis, or not. We evaluated the clinical significance of ECP in serum and BAL fluid in patients with mycoplasmal pneumonia. The diagnosis of mycoplasmal pneumonia was confirmed both by serological diagnosis from paired serum and by the polymerase chain reaction (PCR) methods using specific primers of the Mycoplasma pneumoniae for detecting specific DNA from bronchial washing fluids. ECP level in serum were measured in 27 patients (11 male, 16 female, average age 31.7yo) with mycoplasmal pneumonia by ELISA methods. ECP level in BALF were also measured in ten of all patients. The level of ECP in serum was high in 17 cases (63%) of the total cases. In addition the level of ECP in BALF was also high in all tested patients (10 cases). There was a correlation between serum ECP level and days from onset. There was also a correlation between serum ECP level and WBC counts, the degree of Pa0₂. These results suggested that ECP derived from activated eosinophils in the lung might in part play a role in the pathogenesis of mycoplasmal pneumonia.

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We experienced 142 cases with community-acquired pneumonia between April 1998 and March 2000. By measuring the titers of respiratory viruses for these cases, we were able to identify acute phase infections of influenza A virus in 10 cases and RS virus in 6 cases and determined that there was an increase in community-acquired pneumonia during both winter seasons. Thereafter we compared the clinical features of community acquired pneumonia with regard to these two types of virus infection by dividing the patients into two groups, both of which frequently included in the elderly. In the influenza virus group, such general symptoms as high fever, headache and general fatigue were dominant. Common bacteria were isolated in nine cases with mixed infection; four of them with Streptococcus pneumoniae. In the RS virus group, there were fewer general symptoms and common bacteria were isolated in four cases with mixed infection; three with Haemophilus influenzae. The severity of the illness was greater in the Influenza virus group; i.e.) three cases required mechanical ventilation and two of these three cases died. In the RS virus group, on the other hand, the prognosis was good because no mechanical ventilation was required and there were no deaths.
Influenza vaccination is especially important for the elderly, because the epidemiology of the influenza virus groups showed none had a history of influenza vaccination in this study.

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Two separate febrile Indian patients who reside in Japan and had recently returned from their country were diagnosed as suffering from typhoid fever. Fluoroquinolone therapy was clinically ineffective and the addition of a third-generation cephalosporin was required in each case. Each strain of Salmonella Typhi was resistant to nalidixic acid in vitro and also showed higher minimal inhibitory concentration to other quinolones than usual susceptible strains. Similar cases of typhoid fever responding poorly to quinolone treatment have been observed in the Indian subcontinent, south-east Asia and central Asia since the early 1990s, and potential spread by travelers into Japan is of serious concern. Although quinolones still remain the drugs of choice for treatment of typhoid fever, physiciansshould be aware of the possibility and implications of clinical treatment failure.

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