Development of resistance in Pseudomonas aeruginosa obtained from patients with cystic fibrosis at different times.
OBJECTIVE
Determination of the extent of changes in quantitative resistance in Pseudomonas aeruginosa isolates from patients with cystic fibrosis over a period of approximately 2 years.


METHODS
Three hundred and ninety nine isolates of P. aeruginosa collected from 34 pediatric patients in the period between April 1994 and April 1996 were investigated. During the 2 years the children were treated with a combination of a betalactam and an aminoglycoside, approximately every 3 months. In between they received ciprofloxacin orally, when required. The minimal inhibitory concentrations (MICs) of 38 clones of P. aeruginosa defined by different patterns in macrorestriction analysis (pulse field gel electrophoresis, PFGE) were established for 12 antibiotics: gentamicin, amikacin, tobramycin, ciprofloxacin, levofloxacin, moxifloxacin, trovafloxacin, imipenem, meropenem, ceftazidime, cefepime, and piperacillin by means of broth microdilution tests according to DIN 58940.


RESULTS
Twenty-four of the 38 clones developed increased MIC values during the time of observation especially for aminoglycosides and quinolones. Comparatively less affected were ceftazidime, imipenem and meropenem. An association between the number of the intravenous treatment courses and the increase of the MIC values could not be verified.


CONCLUSIONS
A trend towards an increase of the MICs against antipseudomonal agents was observed over a limited period of time. It is necessary to prevent this development possibly by employing suitable combinations of antibiotics and the introduction of new substances.
Spencker
F B
FB
Institute for Medical Microbiology and Epidemiology of Infectious Diseases, and Department of Pediatrics, University of Leipzig, Leipzig, Germany. spef@medizin.uni-leipzig.de
Staber
L
L
Lietz
T
T
Schille
R
R
Rodloff
A C
AC
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002648:Child; D003550:Cystic Fibrosis / Q000150:complications*; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007769:Lactams / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000639:trends; D011552:Pseudomonas Infections / Q000150:complications / Q000188:drug therapy*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D013997:Time Factors
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D007769:Lactams