Objective Antibiotic restriction can be useful in maintaining bacterial susceptibility. The objective of this study was verify if restriction of cefepime, the most frequently used cephalosporin in our children with acute pneumonia, would ameliorate broadspectrum susceptibility of Gramnegative isolates.

Methods Nine hundred and ninetyfive children with acute pneumonia were divided into 3 cohorts, according to the prevalence of cefepime use in the unit Group 1 n396 comprised patients admitted from January 2004 to December 2005, a period in which cefepime was the most used broadspectrum antibiotic. Patients in Group 2 n349 were admitted when amoxacillintazobactam replaced cefepime January to December 2006 and in Group 3 n250 when cefepime was reintroduced January to December 2007. Meropenem was the alternative thirdline antibiotic for all groups.

Results Multiresistance was defined as resistance to 2 or more unrelated antibiotics, including necessarily a third or fourth generation cephalosporin, piperacillintazobactam or meropenem. Statistics involved KruskalWallis, MannWhitney and logrank tests, KaplanMeier analysis. Groups were comparable in length of stay, time of mechanical ventilation and age. Ninetyeight Gramnegative isolates were analyzed. Patients were more likely to remain free of multiresistant isolates by KaplanMeier analysis in Group 2 when compared to Group 1 p0.017 and Group 3 p0.003. There was also a significant difference in meropenem resistance rates.

Conclusions Cefepime has a greater propensity to select multiresistant Gramnegative pathogens than amoxacillintazobactam and should not be used extensively in children with acute pneumonia.