Analysis of the influence of drug resistance factors on the efficacy of combinations of antibiotics for multidrug-resistant Pseudomonas aeruginosa isolated from hospitals located in the suburbs of Kanto area, Japan.

Infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa are very difficult to treat. The aim of this study was to develop more effective treatments by investigating in vitro the effects of combinations of antibiotics against 47 MDR P. aeruginosa isolates harbouring various resistance factors. The isolates included 41 (87%) metallo-ß-lactamase (MBL)-positive strains, 37 (79%) strains with mutations in OprD and 46 (98%) strains carrying the genes encoding aminoglycoside-modifying enzymes (AMEs). The quinolone resistance-determining region was mutated in all of the strains. These strains were classified into 16 groups according to amplified fragment length polymorphism and resistance factors. The effects of combinations of antibiotics on 16 representative strains were determined using a 'Break-point Checkerboard Plate' assay. Combinations of amikacin+aztreonam (coverage rate, 81.3%) and arbekacin+aztreonam (93.8%) inhibited growth. In contrast, combinations of ciprofloxacin+meropenem (6.3%) and ciprofloxacin+ceftazidime (12.5%) were much less effective. Aztreonam and arbekacin (or amikacin) are not substrates for MBLs and AMEs, respectively. We conclude that the combined effects of these drugs were possibly because of resistance factors.

[Precautions regarding prevent acute urethritis caused by Neisseria meningitidis in Japan].

In Japan, Neisseria meningitidis is not sufficiently recognized as the primary causative bacteria of sexually transmitted diseases (STDs) as the number of reported cases is small. Here, we summarize reports from 3 medical institutions, present clinical courses for each case, as well recommending precautions to prevent infection with this bacterium. Fourteen cases of N. meningitidis urethritis (MU) were admitted between April 2001 and June 2006. All patients were male, consulted a doctor after experiencing subjective symptoms, such as micturition pain and pus discharge, and were diagnosed as having urethritis using isolation culture methods. In 8 of the 14 cases, history of sexual contact in the preclinical stage was confirmed, and contact was with a commercial sex worker (CSW) in 6 of these cases. Many of these patients recalled oral contact. All strains indicated susceptibility to many drugs, and there were no problems with treatment. With regard to serotype, there were 10 cases of type Y, 1 case of type B, and 3 cases that were not classifiable or unidentified. In addition, among the 9 strains that were subjected to genotype identification, 7 strains were ST-23. The recent increase in availability of nucleic acid amplification methods has facilitated simultaneous detection of Neisseria gonorrhoeae and Chlamydia trachomatis. However, we fear that MU will become latent. For screening of urethritis, Gram staining and culture of urethral material must be performed to detect this disease. The relationship of the detected strain and its role in the pathogenesis of meningitis are uncertain, but its serotype and genotype are common in cases of meningitis. Thus, precautions are required to prevent spread of this bacterium.

[In vitro chemosensitivity test for hepatocellular carcinoma using collagen-gel droplet embedded cultures].

This study evaluated an in vitro assay for chemosensitivity test using a collagen-gel droplet-embedded culture drug sensitivity test (CD-DST) for hepatocellular carcinoma (HCC). In 25 patients with HCC, in vitro chemosensitivity to 5-fluorouracil (5-FU), epirubicin (EPI), and cisplatin (CDDP) was examined by CD-DST, and 5-FU, EPI, and paclitaxel (PTX) were examined in 38 patients with breast cancer. Successful rates of chemosensitive evaluation by CD-DST were 64% for HCC and 79% for breast cancers. Although chemosensitivities of breast cancer were 5-FU 23.1%, EPI 83.3%, and PTX 67.7%, only one HCC sample was sensitive to EPI. Growth rates of HCC for 7 days of culture were significantly lower than those of breast cancers (1.04 vs 3.61). The culture methods for HCC in CD-DST should be improved to estimate accurate results.