Impact of cefepime restriction on susceptibility profile of Gram negative bacilli related to healthcare associated infections in a tertiary hospital in Brazil

Background: In recent decades, antimicrobial resistance has become a public health problem, particularly in cases of healthcare associated infections (HAI). Interaction between antibiotic consumption and resistance development is of particular interest regarding to Gram-negative bacilli (GNB), whose growing resistance has represented a great challenge.

Objective: To evaluate the impact of restriction on use of cefepime on antimicrobial susceptibility profile of GNB involved in HAI.

Methods: This quasi-experimental study was conducted in a 150-bed hospital in Sao Paulo, Brazil, specialized in orthopedics care. At this hospital, all antimicrobials are prescribed only by physicians belonging to infection control board (ICB). In May 2007, use of cefepime was restricted by ICB. For this study, it was compared data on hospital occupancy and mortality rates and incidence of HAI in two periods: from May 2005 to May 2007 (24 months prior to restriction) and from May 2007 to May 2009 (24 months after). Data on antimicrobial consumption and susceptibility profile of GNB-related HAI in both periods were also analyzed and compared. Diagnosis of HAI followed criteria defined by the Centers for Disease Control and Prevention (CDC). Cumulative antibiograms were prepared in accordance with standards recommended by the Clinical and Laboratory Standards Institute (CLSI).

Results: There were no differences between two periods in average lengths of hospital stay, hospital mortality rates and overall incidences of HAI. Use of amikacin, aztreonam, ertapenem and levofloxacin increased statistically significant (p <0.05) in second period, while consumption of cefepime, imipenem/cilastin and colistin decreased significantly (p <0.05). There was no difference in the incidences of GNB as causative agents in cases of HAI between the periods. A. baumanii, P. aeruginosa, K. pneumoniae and Enterobacter spp. were the most frequent GNB in both periods. After the restriction of cefepime, susceptibility of A. baumanii improved to gentamicin (p<0,05) and worsened to imipenem (p<0,05). There was no difference in susceptibility to antimicrobials for P. aeruginosa between the two periods. In the second period of this study, the susceptibility of both K. pneumoniae and Enterobacter spp improved to ciprofloxacin (p<0,05). There was no significant change in the incidence of extended spectrum beta lactamamasis (ESBL)-producing Enterobacteriaceae.

Conclusions: After restriction of cefepime, there was an improvement in the susceptibility of A. baumanii to gentamicin and worsening to imipenem. For P. aeruginosa, no significant changes were observed. Regarding K. pneumoniae and Enterobacter spp. significant improvement in susceptibility to ciprofloxacin was observed. There was no impact of this restriction regarding to ESBL-producing Enterobacteriaceae.