Pathogens and resistance

Abstract number: 1732_256

Matsumoto T.

Escherichia coli accounted for about 80% of organisms in uncomplicated UTIs. In contrast, in complicated UTI many kinds of enterobacteriaceae isolates, staphylococci, enterococci, Pseudomonas aeruginosa, and the other glucose-nonfermentable Gram-negative rod (NFGNR) are isolated. Almost nosocomial UTI (NUTI) is complicated UTI. In the 2003 GPIU study (formerly PEP study), NUTI prevalence rate was 9.4% (326/3350). In the 2003 GPIU study, E. coli was the most frequent pathogen, accounting for about 30% of all pathogens isolated. Pseudomonas (13%), Klebsiella (10%), Enterococcus (9%), and Proteus (7%) were isolated frequently. In our hospital, Enterococcus faecalis was the most frequent of all isolated organisms, accounting for 24%. The other enterococci (12%), S. marcescens (12%), P. aeruginosa (9%), the other NFGNR (9%), E. coli (6%), Staphylococcus epidermidis (6%) were isolated frequently. It is considered that these differences occurred by the difference of patients' background.

The fluoroquinolone- and cephem-resistant enterobacteriaceae isolates from patients with NUTI are increasing. Most of the cephem-resistant isolates of E. coli, K. pneumoniae and P. mirabilis are producing Extended-Spectrum b-lactamases (ESBLs). ESBLs are plasmid-mediated broad-spectrum b-lactamases. The ratios of ESBL producers in E. coli and K. pneumoniae are quite different in each country (less than 5% to more than 80%). Most of the nosocomial ESBL producers have acquired resistance to non-b-lactams, such as fluoroquinolones, phosphomycin, co-trimoxazole. Some of the multi-drug resistant isolates have no effective oral antibiotics. According to the 2003–2004 GISP study, the ratios of fluoroquinolone resistance of E. coli and K. pneumoniae accounted for about 20%, respectively, that of enterococci accounted for more than 60%. Mechanisms of resistance to quinolones are mainly target mutations, especially GyrA and ParC. Qnr that is plasmid encoded quinolone resistance reported in 2002. The emergence of qnr also alerts us to the potential rapid dissemination of quinolone-resistant determinants. Qnr shows quinolone specific resistance, but the qnr-plasmids reported are integron-associated and carry multiple resistance determinants providing resistance to several classes of antimicrobials including b-lactams and aminoglycosides.

Multi-drug resistant isolates cause nosocomial spread easily. There are many reports about nosocomial spread of multi-drug resistant ESBL producers. To prevent prevalence of antimicrobial-resistant isolates appropriate antimicrobial selection is needed. Geographic variations in pathogen occurrence and susceptibility profiles require monitoring continuously, and it is important to update treatment guidelines based on susceptibility profile and the results of clinical trials.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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