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Abstract: Multidrug efflux pumps contribute to multiple antibiotic resistance in Pseudomonas aeruginosa. Pump expression usually has been quantified by Western blotting. Quantitative real-time polymerase chain reaction has been developed to measure mRNA expression for genes of interest. Whether this method correlates with pump protein quantities is unclear. We devised a real-time PCR for mRNA expression of MexAB-OprM and MexXY-OprM multidrug efflux pumps. In laboratory strains differing in MexB and MexY expression and in several clinical isolates, protein and mRNA expression correlated well. Quantitative real-time PCR should be a useful alternative in quantitating expression of multidrug efflux pumps by P. aeruginosa isolates in clinical laboratories. [Copyright &y& Elsevier]

We have reported in this journal in vitro susceptibilities of clinical isolates to antibiotics every year since 1992. In this paper, we report the results of an analysis of in vitro susceptibilities of 12,919 clinical isolates from 72 centers in Japan to selected antibiotics in 2007 compared with the results from previous years. The common respiratory pathogens, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae maintained a high susceptibility to fluoroquinolones (FQs). The resistance of S. pyogenes to macrolides has been increasing every year and this was especially clear this year. Most strains of Enterobacteriaceae except for Escherichia coli showed a high susceptibility to FQs. Almost 30% of E. coli strains were resistant to FQs and the resistance increased further this year. FQs resistance of methicillin-resistant Staphylococcus aureus (MRSA) was approximately 95% with the exception of 45% for sitafloxacin (STFX). FQs resistance of methicillin-susceptible S. aureus (MSSA) was low at about 10%. FQs resistance of methicillin-resistant coagulase negative Staphylococci (MRCNS) was higher than that of methicillin-susceptible coagulase negative Staphylococci (MSCNS), but it was lower than that of MRSA. However, FQs resistance of MSCNS was higher than that of MSSA. FQs resistance of Enterococcus faecalis was 22.5% to 29.6%, while that of Enterococcusfaecium was more than 85% except for STFX (58.3%). In clinical isolates of Pseudomonas aeruginosa derived from urinary tract infections, FQs resistance was 21-27%, which was higher than that of P. aeruginosa from respiratory tract infections at 13-21%, which was the same trend as in past years. Multidrug resistant strains accounted for 5.6% in the urinary tract and 1.8% in the respiratory tract. Acinetobacter spp. showed high susceptibility to FQs. The carbapenem resistant strains, which present a problem at present, accounted for 2.7%. Neisseria gonorrhoeae showed high resistance of 86-88% to FQs. The results of the present survey indicated that although methicillin-resistant Staphylococci, Enterococci, E. coli, P. aeruginosa, and N. gonorrhoeae showed resistance tendencies, and other species maintained high susceptibility rates more than 90% against FQs, which have been used clinically for over 15 years.

The control of hospital-acquired infections is a matter of social concern, especially in the proper use of antimicrobial agents. The fundamentals of treatment for infectious diseases involve the exact identification of the responsible bacteria, and the minimum essential use of narrow-spectrum antimicrobial agents for the identified bacteria. We tested the antimicrobial susceptibility of 13 species which belong to the gram-negative rod type and isolated 50 or more strains at Tottori University Hospital in 2001. We evaluated the susceptibility pattern for every species, and have proposed a plan for the sensible use of narrow-spectrum antimicrobial agents. The resistant frequency in the present study was equal to or lower than previously reported. We think that it is possible to use narrow-spectrum antimicrobial agents more often, because the susceptible frequency to these agents was fairly high for some species. It is not too much to say that the history of the development of antimicrobial agents has been a road to broad-spectrum. Though the proper use of antimicrobial agents seems to go against this view, we should remain farsighted. Not only is the publicity of proper use indispensable but excellent surveillance is also highly necessary. We hope for the establishment of a good surveillance system gifted with simplicity, universality, high reproduction and continuity.