[Antimicrobial resistance of clinical isolates of Stenotrophomonas maltophilia].

OBJECTIVE: To investigate the antimicrobial resistance of clinical isolates of Stenotrophomonas matophilia (SMA) and the mechanisms of their drug resistance. METHODS: Disc diffusion method (NCCLS) was used to detect the resistant patterns of 88 initial SMA isolates resistant to 12 antibiotics isolated from a local hospital in the past 4 years. PCR was used to detect the 7 aminoglycosides modifying enzymes genes (AME) against amikacin and gentamicin. Metal-beta-lactamases (MBLs) were screened by synergic method, and extended-spectrum beta-lactamases (ESBLs) were detected by double-disk synergy test. RESULTS: The resistance rates of the SMA isolates were 0%-9.7% to minocycline, 12.5%-22.6% to ticarcillin-clavulanic acid, 12.5%-28.6% to levofloxacin, 18.8%-33.3% to doxycycline, 18.8%-40% to sulfamethoxazole compound, 50%-65.7% to ciprofloxacin, 50%-66.7% to cehazindme, 54.8%-66.7% to amikacin, 75%-100% to gentamicin, 81.3%-100% to piperacillin, 87.5%-100% to aztreonam and 93.5%-100% to imipenem. Aac(3)-I and ant(4')-II were not detected in these strains. The positive rates of the other 5 AME genes of aac(3)-II, ant(2'')-I, aac(6')-I, aac(3)-III, aac(3)-IV were 2.3%, 5.7%, 8%, 10%, and 10%, respectively. SMA strains producing ESBLs were found at the rate of 38.6%; 25% of the strains were MBL-producing, and 13.6% produced both ESBLs and MBLs. CONCLUSION: Most of the SMAs we isolated are multidrug-resistant through various mechanisms. The choice of antibiotics should be made according to the susceptibility results.

[Detection of pathogenicity island-associated genes in enterococcal isolates].

OBJECTIVE: To investigate the presence of pathogenicity island (PAI)-associated genes in the enterococcal isolates. METHODS: Using PCR and hybridization methods, PAI-associated genes were detected in 155 enteococcal strains isolated from clinical patients and healthy individuals. RESULTS: Among the 155 enterococcal isolates, 137 (88.39%) carried at least one of PAI-associated genes, namely hyd (positivity rate of 81.94%), psaA (78.06%), nuc (57.42%), esp (53.55%), cylB (52.90%), and gls24-like (38.06%) genes. Expect for esp gene, the other 5 genes showed higher positivity rates in the E. faecalis strains than in the E. faecium strains, and this difference was statistically significant for the genes nuc, cylB, and gls24-like. The positivity rates and the number of these genes in the E. faecalis from clinical isolates were both significantly higher than those in the strains isolated from healthy individuals. CONCLUSION: The data show a wide distribution of the PAI-associated genes among the enterococcal strains, and E. faecalis strains are more likely than E. faecium strains to be positive for the 6 genes, which are present at significant higher rates in the clinically isolated samples than in that from healthy individuals.