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Diagnostic Microbiology and Infectious Disease 67 (2010) 266 – 269 www.elsevier.com/locate/diagmicrobio
Escherichia coli resistance to quinolones at a comprehensive cancer center☆ Coralia N. Mihua,⁎, Paul R. Rhombergb , Ronald N. Jonesb , Elizabeth Coylec , Randall A. Princec , Kenneth V. Rolstona a
b
The UT M.D. Anderson Cancer Center, Houston, TX 77030, USA Jones Microbiology Institute Laboratories, North Liberty, IA 52317, USA c University of Houston College of Pharmacy, Houston, TX 77204, USA Received 6 November 2009; accepted 14 February 2010
Abstract As part of Meropenem Yearly Susceptibility Test Information Collection/USA Surveillance Programme, we monitored the occurrence of quinolone resistance in Escherichia coli over a 10-year period. A total of 271 E. coli isolates from our institution were tested over a 10-year period. Screening for quinolone resistance (qnr) gene was performed. A decline in susceptibility of E. coli isolates to quinolones and aminoglycosides was noted over the 10-year span (P b 0.0001), which was significantly reduced compared with the average susceptibility of all sites. Introduction of quinolone prophylaxis has led to a significant decline in susceptibility of E. coli to all quinolones. The organisms remain susceptible to carbapenems, cefepime, and piperacillin/tazobactam. Periodic surveillance allows for detection of resistance patterns and adjustment of empiric antibiotic choice in patients at high risk for infection. © 2010 Elsevier Inc. All rights reserved. Keywords: Escherichia coli; Resistance; Quinolones
1. Introduction Bacterial infections remain a serious cause of morbidity and mortality in cancer patients who develop neutropenia (Hughes et al., 2002). Quinolones emerged as preferred
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C.N.M., P.R.R., and K.V.R. have none to declare. E.C has received research funding from Cubist, is a consultant for Astellas and Cubist, and is on the speakers' bureau for Pfizer and Cubist. R.A.P. has received research support from Merck, Astellas, and Enzon. R.N.J. has received research/ education grants from AB BIODISK, Abbott, API, Arpida, Astellas, AstraZeneca, Avexa, Bayer, bioMerieux, Cadence, Cempra, Cerexa, Cornerstone, Cubist, Daiichi, Elan, Elanco, Enanta, Forest, GlaxoSmithKline, Johnson & Johnson (Ortho McNeil), Merck, Novartis, Optimer, Ordway, Pacific Beach, Pfizer, Protez, Replidyne, Schering-Plough, Sequoia, Shionogi, Theravance, TREK Diagnostics, ViroPharma, and Wyeth. ⁎ Corresponding author. Department of Infectious Diseases, Infection Control and Employee Health, The UT M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. Tel.: +1-713-792-2972; fax: +1-713-794-4351. E-mail address:
[email protected] (C.N. Mihu). 0732-8893/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.diagmicrobio.2010.02.014
agents for prophylaxis given several advantages including once a day administration, acceptable safety profile, and broad spectrum of activity. Several randomized trials including 2 recent large trials have assessed the impact of quinolone prophylaxis in neutropenic patients (Bucaneve al., 2005; Cullen et al., 2005). As a recent metaanalysis suggested, the introduction of quinolones as prophylaxis for high-risk patients with hematologic malignancies undergoing intensive chemotherapy has resulted in fewer episodes of neutropenic fever and significantly reduced allcause mortality (Gafter-Gvili et al., 2005). Routine use of quinolones for infection prophylaxis started in our institution in the early 1990s. A major concern of prophylactic use of antibiotics in patients with cancer and neutropenia is that it increases bacterial resistance to these agents. In one report, quinolone prophylaxis increased the colonization with quinolone-resistant organisms, but the rates of infections with such organisms were not increased (Gafter-Gvili et al., 2007). However, microbiologic surveillance data, rates of quinolone resistance developing over
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time, or development of cross-resistance to other antimicrobials remain largely unreported. 2. Materials and methods Our institution participated in the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program. From 1999 through 2008, 271 isolates of Escherichia coli from blood stream infections of patients in the intensive care unit were collected from our institution. Concomitantly, a total of 4416 clinical isolates of E. coli were collected from 14 other geographically dispersed institutions. Identification of the isolates was confirmed at a central laboratory (JMI Laboratories, North Liberty, IA). Antimicrobial susceptibility testing was performed on all isolates in accordance with Clinical and Laboratory Standards Institute (CLSI, formerly National Committee for Clinical Laboratory Standards) M7-A7 methods. All isolates were tested for 11 antimicrobials (meropenem, imipenem, ertapenem, cefepime, ceftazidime, ceftriaxone, piperacillin/ tazobactam, tobramycin, gentamycin, ciprofloxacin, and levofloxacin) using broth microdilution method. Quinolone resistance was defined as ciprofloxacin MIC N2 μg/mL. The CLSI extended-spectrum β-lactamase (ESBL) MIC screening criteria (N2 μg/mL for ceftazidime or ceftriaxone) were also applied as described in earlier MYSTIC monitoring reports (Castanheira et al., 2008). Isolates were screened for the plasmid-encoded quinolone resistance genes: qnrA, qnrB, and qnrS according to a previously described protocol (Mammeri al., 2005; Poirel et al., 2006). Polymerase chain reaction amplicons were sequenced on both strands and the nucleotide sequence, and deduced amino acid sequences were analyzed using the Lasergene software package (DNASTAR, Madison, WI). Sequences were compared with others available via internet sources (http://www.ncbi.nlm.nih.gov/blast/). At least 1
Fig. 1. Annual susceptibility rate of E. coli to meropenem, cefepime, piperacillin/tazobactam, tobramycin, and ciprofloxacin at MD Anderson Cancer Center (MDACC).
Fig. 2. Annual percentage of susceptibility to ciprofloxacin of E. coli isolates from MDACC compared with all sites.
amplicon of each type was sequenced and used as a control for the following experiments. Isolates from the same medical center showing the same susceptibility antibiogram were characterized by pulsed-field gel electrophoresis (PFGE) and/or automated ribotyping (Riboprinter™ Microbial Characterization System; Qualicon, Wilmington, DE) to evaluate for clonality. Genomic DNA was prepared in agarose gel and digested with SpeI (New England, Beverly, MA), and electrophoresis was performed on the CHEF-DR III apparatus (BioRad, Richmond, CA). 3. Results Fig. 1 illustrates in vitro susceptibility rates of E. coli isolates from our institution to commonly used antimicrobials. It demonstrates a significant decline over a 10-year period (Pb.0001). Susceptibility to tobramycin also declined over time. Meropenem, cefepime, and piperacillin/tazobactam showed in vitro susceptibility rates against E. coli with 90% to 100% of the isolates being susceptible. The yearly ciprofloxacin susceptibility rate of E. coli from our institution compared with all participating sites is shown in Fig. 2. Although there is a universal trend toward declining susceptibilities to ciprofloxacin, our institution has significantly lower rates of susceptibility. Based on CLSI screening criteria for ESBL, the percentage of ESBLproducing strains of E. coli in our institution during this period ranged from 4.5% to 19.4% (Fig. 3). Twenty-two resistant E. coli isolates were studied for clonality in 2004 to 2005. Twelve (54.5%) exhibited an identical ribotype and PFGE pattern suggesting an endemic clone, whereas 10 other isolates showed variability of ribotype and PFGE patterns. During 2006 to 2007, 22 strains underwent screening for plasmid-encoded quinolone resistance. Two of 22 strains (9%) were positive for qnrA and qnrB2, respectively. The isolate carrying qnrB2 gene also tested positive for the ESBL enzyme, Cefotaximase-15.
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Fig. 3. Number of E. coli isolates submitted by MDACC.
4. Discussion After their introduction in clinical practice, quinolones demonstrated excellent activity across a wide range of pathogens including enteric Gram-negative bacilli and Pseudomonas, making them ideal drugs for use in prophylaxis and treatment of febrile patients with neutropenia. A study from our institution published in 1999 reported susceptibility rates of 84% to 100% for all species of Enterobacteriaceae. Specifically for E. coli, 94% of isolates were susceptible to ciprofloxacin and levofloxacin (Jacobson et al., 1999). Widespread use of quinolones for prophylaxis and treatment has inevitably led to emergence of resistance. Particularly for E. coli, there have been several studies reporting emergence of quinolone-resistant E. coli associated with quinolone use, but the impact on the rates of clinically significant infections is unclear (Carratala et al., 1995; Cattaneo et al., 2008; Kern et al., 1994). In the present report, we focused on E. coli blood stream isolates obtained from critically ill patients. Our data show a significant decline in quinolone susceptibility among these isolates. Although direct causality is not established, we associate this trend with the widespread use of quinolone prophylaxis. This decline was more significant at our institution when compared with other participating centers. This trend appears more obvious when compared with 84% to 100% susceptibility rates reported in the 1990s (Jacobson et al., 1999). Similarly, because aminoglycosides are routinely used as part of empiric regimens for neutropenic fevers, especially if quinolones were also used for prophylaxis, there is a trend toward declining susceptibilities of this class of antibacterials. Carbapenems, cefepime, and piperacillin/tazobactam retain excellent in vitro activity for the majority of E. coli isolates. Despite these in vitro data, based on CLSI screening criteria, 4.5% to 19.4% of E. coli isolates were ESBL producing; current recommendations preclude use of cephalosporins to treat ESBL-producing isolates. Quinolone resistance occurs as a result of multiple mechanisms. Recently, a plasmid-encoded quinolone resis-
tance (qnr) gene was described, which allows spread of resistance to other antimicrobials (i.e., ESBL) (Poirel et al., 2005; Poirel et al., 2006; Tran and Jacoby 2002). More recently, the presence of aac(6′)-Ib-cr and qepA quinolone resistance mechanisms have also been described; however, the presence of these mechanism were not investigated (Park et al., 2007). Starting in 2002, ribotyping followed up with PFGE was performed on the resistant isolates. Interestingly, over a 2-year period, half of the resistant isolates demonstrated the same ribotype and PFGE pattern, whereas the other half had no clonal pattern suggesting both independent development and horizontal spread of resistance mechanisms. In parallel, ESBL production of the E. coli isolates has increased over the years, reaching 12% to 19% of all clinically significant isolates submitted. Two (10%) of the quinolone-resistant isolates tested harbored qnr genes, 1 of the 2 isolates containing both qnr and CTX-M-15, confirming previous reports suggesting that mobile genetic elements may transmit resistance to multiple classes of antibiotics. Based on our data, carbapenems, cefepime, and piperacillin/tazobactam remain the most useful antimicrobials for treatment of severe E. coli infections. For each individual institution, structured surveillance allows for detection of mechanisms and patterns of resistance, dictating adjustment of empiric antibiotic choice in patients at high risk for infection. Effective infection control measures are needed to prevent spread of these resistant organisms. References Bucaneve G, Micozzi A, et al (2005) Levofloxacin to prevent bacterial infection in patients with cancer and neutropenia. N Engl J Med 353:977–987. Carratala J, Fernandez-Sevilla A, et al (1995) Emergence of quinoloneresistant Escherichia coli bacteremia in neutropenic patients with cancer who have received prophylactic norfloxacin. Clin Infect Dis 20:557–560 discussion 561–3. Cattaneo C, Quaresmini G, et al (2008) Recent changes in bacterial epidemiology and the emergence of fluoroquinolone-resistant Escherichia coli among patients with haematological malignancies: results of a prospective study on 823 patients at a single institution. J Antimicrob Chemother 61:721–728. Castanheira M, Mendes R, et al (2008) Rapid emergence of blaCTX-M among Enterobacteriaceae in U.S. medical centers; molecular evaluation from the MYSTIC Program (2007). Microb Drug Resist 14:211–216. Cullen M, Steven N, et al (2005) Antibacterial prophylaxis after chemotherapy for solid tumors and lymphomas. N Engl J Med 353: 988–998. Gafter-Gvili A, Fraser A, et al (2005) Meta-analysis: antibiotic prophylaxis reduces mortality in neutropenic patients. Ann Intern Med 142(12 Pt 1):979–995. Gafter-Gvili A, Paul M, et al (2007) Effect of quinolone prophylaxis in afebrile neutropenic patients on microbial resistance: systematic review and meta-analysis. J Antimicrob Chemother 59:5–22. Hughes WT, Armstrong D, et al (2002) 2002 guidelines for the use of antimicrobial agents in neutropenic patients with cancer. Clin Infect Dis 34:730–751.
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