Some antimicrobial agents have been reported to modify the host immune and inflammatory responses both in vivo and in vitro. Fosfomycin (FOM) and clarithromycin (CAM) have immunomodulatory activity on human lymphocyte function. In the present study, we examined the effects of FOM and CAM on cytokine synthesis by lipopolysaccharide (LPS)-stimulated human monocytes in comparison with that of dexamethasone in vitro.The three drugs demonstrated positive or negative effects on the synthesis of various cytokines by LPS-primed monocytes. They suppressed the synthesis of tumor necrosis factor alpha, interleukin 1␣ (IL-1␣), IL-1␤, the IL-1 receptor antagonist, and granulocyte-macrophage colony-stimulating factor in a concentration-dependent manner at concentrations between 1.6 and 40 g/ml. On the contrary, the drugs showed different actions on the synthesis of IL-6 and IL-10. Namely, FOM enhanced both IL-6 and IL-10 synthesis, CAM enhanced only IL-10 synthesis, but dexamethasone deeply suppressed the synthesis of both cytokines. These data indicate that antibacterial agents may modify acute-phase inflammatory responses through their effects on cytokine synthesis by monocytes.

We previously reported an outbreak in a neurosurgery ward of catheter-associated urinary tract infection with multidrug-resistant (MDR) Pseudomonas aeruginosa strain IMCJ2.S1, carrying the 6-N-aminoglycoside acetyltransferase gene [aac(6)-Iae]. For further epidemiologic studies, 214 clinical isolates of MDR P. aeruginosa showing resistance to imipenem (MIC > 16 g/ml), amikacin (MIC > 64 g/ml), and ciprofloxacin (MIC > 4 g/ml) were collected from 13 hospitals in the same prefecture in Japan. We also collected 70 clinical isolates of P. aeruginosa that were sensitive to one or more of these antibiotics and compared their characteristics with those of the MDR P. aeruginosa isolates. Of the 214 MDR P. aeruginosa isolates, 212 (99%) were serotype O11. We developed a loop-mediated isothermal amplification (LAMP) assay and a slide agglutination test for detection of the aac(6)-Iae gene and the AAC(6)-Iae protein, respectively. Of the 212 MDR P. aeruginosa isolates, 212 (100%) and 207 (98%) were positive in the LAMP assay and in the agglutination test, respectively. Mutations of gyrA and parC genes resulting in amino acid substitutions were detected in 213 of the 214 MDR P. aeruginosa isolates (99%). Of the 214 MDR P. aeruginosa isolates, 212 showed pulsed-field gel electrophoresis patterns with >70% similarity to that of IMCJ2.S1 and 83 showed a pattern identical to that of IMCJ2.S1, indicating that clonal expansion of MDR P. aeruginosa occurred in community hospitals in this area. The methods developed in this study to detect aac(6)-Iae were rapid and effective in diagnosing infections caused by various MDR P. aeruginosa clones.Pseudomonas aeruginosa causes nosocomial infections as a result of its ubiquitous nature, ability to survive in moist environments, and resistance to many antibiotics and antiseptics. A serious problem is the emergence of multidrug-resistant (MDR) P. aeruginosa strains resistant to ␤-lactams, aminoglycosides, and quinolones (34,39,46 We previously reported a nosocomial outbreak of catheterassociated urinary tract infection involving new MDR P. aeruginosa strain IMCJ2.S1, which occurred in a neurosurgery ward of a hospital located in the Tohoku area of Japan (46). This strain showed broad-spectrum resistance to aminoglycosides, ␤-lactams, fluoroquinolones, tetracyclines, sulfonamide, and chlorhexidine. We found that IMCJ2.S1 harbored a novel class 1 integron, In113, containing an array of three gene cassettes of the metallo-␤-lactamase (MBL) bla IMP-1 gene, aminoglycoside 6Ј-acetyltransferase aac(6Ј)-Iae gene, and aminoglycoside 3Ј-adenylyltransferase aadA1 gene (46). This strain possessed mutations of the gyrA (83Thr3Ile) and parC (87Ser3Leu) genes involving amino acid substitutions, resulting in high-level resistance to fluoroquinolones.In the geographic area where the MDR P. aeruginosa outbreak occurred (46), hospitals and a commercial clinical laboratory were surveyed for similar organisms. Because 99% of the MDR P. aeruginosa isolates analyzed were found to harbor the aac(6Ј)-Iae gene, we d...

Toxic shock syndrome toxin-1 (TSST-1)-binding assay using 125I-labeled TSST-1 showed the presence of specific TSST-1 binding in a B cell fraction of human peripheral blood mononuclear cells and L cells transfected with DR2 genes or DR4 genes but not in a T cell fraction and control L cells. Fixation with paraformaldehyde, an inhibitor of antigen processing, did not remove TSST-1-binding activity of the transfectants. Binding of 125I-labeled TSST-1 to the transfectants was reduced by an anti-DR monoclonal antibody. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a single band with TSST-1-binding activity and the same migration pattern as DR heterodimers. TSST-1-induced T cell responses, proliferation and interleukin 2 (IL2) production were observed in the presence of the transfectants but not in the presence of control L cells, while concanavalin A-induced IL2 production was observed in the presence of either the transfectants or control L cells. Presence of an anti-DR monoclonal antibody inhibited the TSST-1-induced responses. Paraformaldehyde-fixed Daudi cells were effective in supporting TSST-1-induced IL2 production by T cells. These results indicate that HLA class II molecules directly bind intact TSST-1 and perform an essential role as the TSST-1-binding structures on accessory cells in T cell activation by the toxin.

A novel gene, dfrG, encoding a trimethoprim (TMP)-resistant dihydrofolate reductase (DHFR, designated S3DHFR) was cloned from a clinical isolate of methicillin-resistant Staphylococcus aureus. Escherichia coli expressing dfrG was highly resistant to TMP. Recombinant S3DHFR exhibited DHFR activity that was not inhibited by TMP

To evaluate the susceptibility of a large number of strains to various antiseptics, we elaborated a simple, qualitative broth turbidity method in which we could quickly judge the efficacy visually. For this method, we prepared a modified neutralizer broth, consisting of trypticase soy broth containing 15% Tween 80, 1% soybean lecithin and 0.5% sodium thiosulfate. The susceptibilities of Serratia marcescens No. 26 to 4 antiseptics obtained from the turbidity method showed a good agreement with those obtained from the colony-counting method; the 4 antiseptics tested were povidone-iodine (PVP-I), chlorhexidine gluconate (CHG), benzalkonium chloride (BAC) and alkyldiaminoethylglycine hydrochloride (AEG). Both PVP-I and BAC had complete efficacy in 0.5 min against all isolates tested [100 isolates of S. marcescens, 103 of Klebsiella pneumoniae, 99 of Pseudomonas aeruginosa, 19 of Alcaligenes faecalis and 30 of A. xylosoxidans subsp. xylosoxydans (A. xylosoxydans)]. In contrast, the effectiveness of CHG was weak compared with PVP-I, BAC and AEG. Strong resistance against AEG was noted even after 3-min exposure in 1 isolate each of A. faecalis and A. xylosoxydans. It is concluded that the turbidity test is a simple and accurate method to evaluate susceptibility to various antiseptics and that it is suitable for a screening of a large number of strains. Among the 4 antiseptics tested, PVP-I and BAC showed a consistently high activity against all isolates, confirming PVP-I and BAC to be clinically useful antiseptics.