Emergence of resistance in Pseudomonas aeruginosa and Acinetobacter species after the use of antimicrobials for burned patients.
OBJECTIVE
To evaluate the emergence of resistance of Pseudomonas aeruginosa and Acinetobacter species to imipenem, ciprofloxacin, or both after the use of these drugs and to compare resistant with susceptible isolates by molecular typing.


METHODS
Cohort study.


METHODS
Burn intensive care unit (ICU) with 4 beds in a tertiary-care university hospital.


METHODS
During 16 months, surveillance cultures were performed for all patients admitted to the ICU. Demographic information was obtained for each patient. Molecular typing was done by pulsed-field gel electrophoresis using restriction enzymes for 71 isolates of P. aeruginosa and Acinetobacter species.


RESULTS
Thirty-four patients were admitted and 22 were colonized by susceptible P. aeruginosa or Acinetobacter species before they used the antimicrobials. Nine (41%) of these patients had a resistant isolate after antimicrobial use: 5 had used imipenem alone, 1 had used ciprofloxacin, and 3 had used both drugs. The interval between isolation of the susceptible and resistant isolates ranged from 4 to 25 days, but was 10 or more days for 6 patients. Molecular typing revealed that susceptible and resistant isolates from each patient were different and that although there were no predominant clones among susceptible isolates, there was a predominant clone among resistant isolates of P. aeruginosa and of Acinetobacter.


CONCLUSIONS
Resistance was not due to the acquisition of resistance mechanisms by a previously susceptible strain, but rather to cross-transmission. Although various measures involving antimicrobial use have received great attention, it would seem that practices to prevent cross-transmission are more important in controlling resistance.
Ferreira
Andrea C B
AC
Hospital das Clínicas, Faculdade de Medicina, University of São Paulo, São Paulo, Brazil.
Gobara
Satiko
S
Costa
Silvia E
SE
Sauaia
Naim
N
Mamizuka
Elsa M
EM
van der Heijden
Inneke M
IM
Soares
Robson E
RE
Almeida
Gisele D
GD
Fontana
Carlos
C
Levin
Anna S
AS
D000150:Acinetobacter / Q000187:drug effects* / Q000302:isolation & purification; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002056:Burns / Q000188:drug therapy*; D002939:Ciprofloxacin / Q000494:pharmacology* / Q000627:therapeutic use; D015331:Cohort Studies; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D015378:Imipenem / Q000494:pharmacology* / Q000627:therapeutic use; D007362:Intensive Care Units; D008297:Male; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D015378:Imipenem