Impact of Previous Use of Antibiotics on Development of Resistance to Extended-Spectrum Cephalosporins in Patients with Enterobacter Bacteremia

Abstract

This retrospective study was conducted to determine the risk factors for resistance to extended-spectrum cephalosporins (ESCs) and to examine the influence of previous use of an aminoglycoside with an ESC on resistance to ESCs in patients with Enterobacter bacteremia from January 1991 through December 2000. A total of 423 episodes of Enterobacter bacteremia among 414 patients were documented during the 10-year study period. Three hundred thirty-two (78%) isolates were Enterobacter cloacae, 72 (17%) Enterobacter aerogenes, and 19 (4%) other Enterobacter species. Causative isolates exhibited resistance to ESCs in 225 episodes and susceptibility in 198 episodes. Nosocomial acquisition was an independent risk factor for resistance to ESCs (odds ratio [OR], 3.4; 95% confidence interval [95%CI], 1.7-6.8). The median number of antibiotics used was significantly greater in cases caused by resistant isolates than in cases caused by susceptible isolates (OR, 1.8; 95%CI, 1.2-2.6). Resistance to ESCs was associated with previous use of any ESC (OR, 5.0; 95%CI, 2.5-10.2). The proportion of resistant episodes in patients treated previously with an aminoglycoside plus an ESC was not different from that in patients treated with an ESC alone. In conclusion, previous use of ESCs was associated with resistance to ESCs in patients with Enterobacter bacteremia; moreover, previous use of an aminoglycoside with an ESC did not significantly decrease the risk of resistance to ESCs.

Enterobacter Bacteremia: Clinical Features, Risk Factors for Multiresistance and Mortality in a Chinese University Hospital

“…The species most commonly causing Enterobacter bacteremia was E. cloacae (77.8%) in our study, which was consistent with a previous report (78%) [10]. Enterobacter bacteremia is frequently polymicrobial.…”

“…The number showed the global mortality of Enterobacter bacteremia had evidently increased in recent 10 years. It might be explained with the higher nosocomial infection and multiresistance [10,19]. Because septic shock is an intermediate variable on the causal pathway to death [20], we excluded it in the multivariate analysis of the mortality.…”

Emergence of Antibiotic Resistance during Therapy for Infections Caused by Enterobacteriaceae Producing AmpC β-Lactamase: Implications for Antibiotic Use

“…In a prospective, case-controlled observational study of organisms producing the AmpC ␤-lactamase, episodes of resistance were less frequent in patients treated with a broad-spectrum cephalosporin plus an aminoglycoside than in those treated with a broad-spectrum cephalosporin alone (6). In our study, however, the incidence of the emergence of resistance did not differ significantly between patients receiving monotherapy and those receiving combination therapy, which is consistent with the findings of previous cohort studies (2,8). Even if combination therapy cannot prevent the emergence of resistance, it may be considered, since it is likely that a particular strain would become resistant to only one of the two agents but remain susceptible to the other (2).…”

Effect of Aminoglycoside and β‐Lactam Combination Therapy versus β‐Lactam Monotherapy on the Emergence of Antimicrobial Resistance: A Meta‐analysis of Randomized, Controlled Trials

“…For example, 3 studies that examined the emergence of antimicrobial resistance in initially antimicrobial-susceptible Enterobacter clinical isolates reported different results. Chow et al [76] (in a prospective, noninterventional study) and Lee et al [77] (in a retrospective study) reported that emergence of resistance to the administered blactam therapy did not occur less frequently among patients receiving aminoglycoside/b-lactam combination therapy than among patients receiving b-lactam monotherapy. On the other hand, in a retrospective study, Kaye et al [78] reported a lower rate of emergence of antimicrobial resistance with the use of aminoglycoside/b-lactam combination therapy, compared with b-lactam monotherapy, although this finding was not statistically significant.…”