Comparative in vitro analysis of different antimicrobial agent action/activity against Pseudomonas aeruginosa strains isolated from human infections

Comparative in vitro analysis of different antimicrobial agent action/activity against Pseudomonas aeruginosa strains isolated from human infections.

THESIS: N. B. M. Ferrari submitted this dissertation for her Masters in Tropical Diseases at Botucatu School of Medicine, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil, 1999.

Advisor: Professor Carlos Alberto de Magalhães Lopes

^{Address to correspondence}

ABSTRACT:Pseudomonas aeruginosa is a widely distributed pathogen, found in all environments, such as water and soil. These organisms infect compromised in-patients submitted to invasive procedures, such as the use of probes, catheters, and ventilators. They are either intrinsically resistant microorganisms or become resistant through genetic recombination. Their resistance results from selective pressure factors by the constant use of antimicrobials, which act as selective and/or generator resistance factors. In this study, we analyzed 120 Pseudomonas aeruginosa strains from in-patients of the Hospital das Clínicas da Faculdade de Medicina – Campus de Botucatu – UNESP. Antimicrobial sensitivity was analyzed using the disk diffusion and the dilution methods, following recommendations of the National Committee for Clinical Laboratory Standards (NCCLS). Discrepancy indices were observed between the two methods, and the Time-Kill curve was performed on the multi-resistant strains submitted to the association of several drugs. In general, the results show compatibility between strain percentages sensitive to both methods, and the best antimicrobial agents imipenem and ceftazidime at minimum inhibitory concentrations (MICs) of 32 mg/ml and 64 mg/ml, respectively. The results also show the highest percentages for strains false sensitive to ciprofloxacin (8.3%) and strains false resistant to carbenicillin (15%). Analyses of association were performed for ciprofloxacin with chloramphenicol, gentamicin, imipenem, aztreonam, cefepime, and amikacin and for amikacin with aztreonam, cefepime and ceftazidime; a synergist effect was seen for the following associations: ciprofloxacin with gentamicin, chloramphenicol, and imipenen; and amikacin with ceftazidime, cefepime, imipenem, and aztreonam. Our data suggest that these latter results are a viable alternative for the control of infections caused by multi-resistant Pseudomonas aeruginosa.

Key words:Pseudomonas aeruginosa, antimicrobial sensitivity, antibiotics.

Publication Dates

• Publication in this collection
  09 Dec 2003
• Date of issue
  2003