Antimicrobial susceptibility and resistance of non-aeruginosa pseudomanas spp., west general hospital, Caracas, Venezuela (1997-2003) Non-aeruginosa pseudomonas spp drug resistance

Abstract

Objective: To investigate the antimicrobial resistance among non-fermenting gramnegative bacilli, particularly, non-aeruginosa Pseudomonas species. Significance: Surveillance of this pathogens, because the antimicrobial resistance among nonfermenting gram-negative bacilli has increased significantly in Venezuela in recent years. Study: We evaluated non-aeruginosa Pseudomonas species strains isolates collected from patients with suspected infections in a hospital of Caracas, Venezuela (West General Hospital) between 1997–2003. Study population: For the studied period, 146 clinical strains of non-aeruginosa Pseudomonas species were isolated, we consider also in this analysis related species: Burkholderia, Stenotrophomonas, Flavimonas, Sphingomonas, Ralstonia and Comamonas. Methodology: Clinical samples were processed and identified with standard cultures and biochemical tests. In vitro antimicrobial susceptibility of the isolates was assessed by an agar disk diffusion method using Mueller-Hinton agar as recommended by the National Committee for Clinical Laboratory Standards (NCCLS). Isolates were tested against 15 drugs: imipenem, meropenem, aztreonam, piperacillin, tobramycin, amikacin, gentamicin, ceftazidime, cefepime, netilmicin, cefoperazone, ciprofloxacin, levofloxacin, lomefloxacin, ofloxacin. Epi Info v.6.0 was used in statistical analysis. Results: From total isolated strains, 50.7% corresponded to Stenotrophomonas maltophilia, 21.2% to Burkholderia cepacia, 17.8% to P. fluorescens, 4.1% to P. putida, 1.4% to P. stutzeri, 1.4% to Flavimonas oryzihabitans, 1.4% to Sphingomonas paucimobilis, 1.4% to Ralstonia pickettii, 0.7% to P. mendocina, 0.7% to Comamonas testosteroni. S. maltophilia showed high resistance to carbapenemes (100% of resistance to imipenem and meropenem), and a considerable susceptibility to certain quinolones (63.6% of susceptibility to ciprofloxacin and 95.% to levofloxacin). B. cepacia displayed higher resistance to gentamicin (58.3%) and high susceptibility levels to carbapenems (80.0% to meropenem and 88.5% to imipenem). P. fluorescens showed high resistance to piperacillin and gentamicin (55.6% and 47.8% respectively) and high susceptibility to quinolones (72.7% for ofloxacin, 73.9% for ciprofloxacin and 80.0% to lomefloxacin). P. putida showed higher resistance for amikacin and ciprofloxacin (50%, both). Conclusions: The high rates of antimicrobial resistance among these bacterial pathogens in this hospital are important. Judicious use of antimicrobial agents can never be overemphasized. Continued surveillance of the changes of resistance patterns over time is necessary.