[Multiresistant Pseudomonas spp. in vitro susceptibility to a combination of two antibiotics].
BACKGROUND
In vitro antibiotic combination testing would guide therapy selection in patients severely affected by multi-drug resistant Pseudomonas.


OBJECTIVE
In vitro, a two-antibiotic combination susceptible against multi-drug resistant Pseudomonas isolated at the Laboratorio Clínico of the Hospital de Oncología, Centro Médico Nacional Siglo XXI in Mexico City were analyzed to determine which antibiotic combination showed the best bactericidal activity.


METHODS
During 10 months, 30 multi-drug resistant Pseudomonas strains were tested. An automated method was used, including a diluting solution with a well-known concentration of a second antibiotic. Quality controls recommended by the NCCLS were used. Pseudomonas aeruginosa ATCC 27853; Escherichia coli ATCC 25922; and Escherichia coli ATCC 35218. Combinations were betalactamics-aminoglycosides; carbapenemis-amikacin; fluoroquinolones-cefepime; and ciprofloxacin-ampicillin.


RESULTS
Ampicillin-ciprofloxacin combination was bactericidal against 100% of the isolates. Cefazolin, cefixime and ticarcillin with amikacin: <50%; aztreonam, cefoxilin, cefuroxime, cefotaxime, ceftazidime and piperacillin with amikacin: 50-60%; cefepime with gentamicin: 76%; cefepime with amikacin: 86%; imipenem and meropenem with amikacin: 70% and 76%; cefepime with ciprofloxacin: 83%; cefepime with levofloxacin: 73%.


CONCLUSIONS
In vitro antibiotic combination susceptibilities against multi-drug resistant bacteria would be the only way to guide clinicians to select the best therapy in severe infections. We found that the ampicillin-ciprofloxacin combination showed the best in vitro effect against multi-drug resistant Pseudomonas.
Pliego-Castañeda
Q F B Amanda
QF
Laboratorio de Microbiología, Hospital de Oncología, Centro Médico Nacional Siglo XXI, IMSS. pliegoamanda@yahoo.com.mx
Yánez-Viguri
Jorge Antonio
JA
López-Valle
Tiburcio
T
D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004359:Drug Therapy, Combination; D006801:Humans; D008826:Microbial Sensitivity Tests; D011549:Pseudomonas / Q000187:drug effects*; D015363:Quinolones / Q000494:pharmacology; D047090:beta-Lactams / Q000494:pharmacology
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D015363:Quinolones; D047090:beta-Lactams