Diagnostic Microbiology and Infectious Disease 94 (2019) 88–92 Contents lists available at ScienceDirect Diagnostic Microbiology and Infectious Disease journal homepage: www.elsevier.com/locate/diagmicrobio In vitro activity of flomoxef against extended-spectrum β-lactamase–producing Escherichia coli and Klebsiella pneumoniae in Korea Younghee Jung a, Seung Soon Lee a,⁎,1, Wonkeun Song b,1,Han-SungKimc, Young Uh d a Division of Infectious Diseases, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine,Anyang,SouthKorea b Department of Laboratory Medicine, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, South Korea c Department of Laboratory Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, South Korea d Department of Laboratory Medicine, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju, South Korea article info abstract Article history: To find an alternative regimen for the treatment of extended-spectrum β-lactamase (EBSL)–producing Received 15 September 2018 Enterobacteriaceae infections, we examined the in vitro activity of flomoxef against Escherichia coli and Klebsiella Received in revised form 18 November 2018 pneumoniae having CTX-M-1 group and/or CTX-M-9 group ESBLs. Boronic acid disk methods and polymerase Accepted 21 November 2018 chain reaction amplification were used to detect for ESBL, and AmpC β-lactamase and AmpC β-lactamase Available online 26 November 2018 co-producers were excluded. Minimum inhibitory concentrations (MICs) were determined for flomoxef by broth microdilution. One hundred seventy-six isolates (E. coli, n =93andK. pneumoniae, n = 83) were analyzed Keywords: fl Flomoxef for susceptibility test. A total of 94.3% (166/176) of isolates were susceptible to omoxef (MIC50/MIC90 were μ μ Cephamycins 0.5/8 g/mL); 98.9% of the ESBL-producing E. coli (MIC50/MIC90 were 1/4 g/mL) and 89.2% of the Extended-spectrum β-lactamase–producing ESBL-producing K. pneumoniae (MIC50/MIC90 were 0.5/16 μg/mL) were susceptible to flomoxef. Flomoxef Enterobacteriaceae has good in vitro activity against ESBL-producing E. coli and K. pneumoniae and could be considered as an alternative for infections caused by these organisms. © 2018 Elsevier Inc. All rights reserved. 1. Introduction cephalosporin nuclei, have been reported to be highly active against ESBL-producing organism in vitro (Jacoby and Carreras, 1990), but Extended-spectrum β-lactamases (ESBLs) confers resistance to they have not been evaluated as much as β-lactam and β-lactamase in- most commonly used β-lactam antimicrobial agents and often to hibitors in clinical studies. This is because there were early reports of a other classes of antibiotics concurrently, thus limiting the choice of an- few cases of in vivo resistance during treatment with cephamycins tibiotic to carbapenems. Following the increased use of carbapenems, (Pangon et al., 1989; Siu et al., 1999). Therefore, the use of this drug to carbapenem-resistant Enterobacteriaceae (CRE) emerged and spread treat ESBL-producers was somewhat discouraged. Flomoxef is unique rapidly worldwide (Chia et al., 2010). CRE is a serious threat to public among cephamycins in having a difluoromethylthio-acetamido group health, as infection with these organisms can be fatal, with mortality at position 7, which improves its in vitro activity against ESBL- rates as high as 40–50% (Patel et al., 2008). Consequently, there has producing Enterobacteriaceae (Bauernfeind et al., 1991; Jacoby and been much effort to reduce the use of carbapenems, as this would re- Carreras, 1990). Since Lee et al. firstly reported in vivo activity of duce the selection pressure for CRE. In this respect, possible alternative flomoxef against ESBL-producers, a few clinical studies have evaluated regimens to carbapenems for treating ESBL infections without the clinical efficacy of cephamycins, mainly flomoxef, as alternatives compromising treatment outcomes have been frequently evaluated in to carbapenems for the treatment of ESBL infections (Doi et al., 2013; observational studies. The candidates are β-lactam and β-lactamase Fukuchi et al., 2016; Lee et al., 2006, 2015b; Matsumura et al., 2015; inhibitor combinations, cefepime, quinolones, and cephamycins. Yang et al., 2012). Along with these clinical studies, the in vitro activity Piperacillin–tazobactam is to date the most studied alternative, and its of flomoxef against clinical ESBL-producing isolates has been efficacy seems to be not inferior to that of carbapenems, at least in reevaluated in Japan, China, and Taiwan (Matsumura et al., 2016; mild to moderate infections (Tamma and Rodriguez-Bano, 2017). Yang et al., 2015a, 2015b). Cephamycins (e.g., cefotetan, cefoxitin, cefmetazole and flomoxef), According to the Clinical and Laboratory Standards Institute (CLSI), which have a methoxy group at the 7-alpha position of their ESBL-producing E. coli and K. pneumoniae should be reported as resis- tant to moxalactam regardless of MIC value, and the cutoff for flomoxef is not currently determined. This is because moxalactam and flomoxef ⁎ Corresponding author. Tel.: +82-31-380-3724; fax: +82-31-381-3724. have been used mainly in Asia, and data about their pharmacokinetics E-mail addresses: [email protected] [email protected] (S.S. Lee). 1 Seung Soon Lee and Wonkeun Song contributed equally to this work as corresponding (PK) and pharmacodynamics (PD) in ESBL infections are scarce even authors. though moxalactam and flomoxef have potent in vitro activity against https://doi.org/10.1016/j.diagmicrobio.2018.11.017 0732-8893/© 2018 Elsevier Inc. All rights reserved. Y. Jung et al. / Diagnostic Microbiology and Infectious Disease 94 (2019) 88–92 89 ESBL-producing isolates (Bauernfeind et al., 1991; Carmine et al., 1983; done in previous studies (Matsumura et al., 2016; Yang et al., 2015a, Jacoby and Carreras, 1990). However, recent PK/PD analysis has re- 2015b) for comparison purposes only. vealed that flomoxef and moxalactam have bactericidal activity against ESBL-producing isolates (Huang et al., 2018; Ito et al., 2013, 2014). This 3. Results suggests that moxalactam and flomoxef may be promising alternatives in treatment of ESBL infections. 3.1. ESBL-producing isolates and their genotypic distribution Flomoxef has been available in South Korea since 1990s and has been used in intra-abdominal infections and gynecologic infections, A total of 237 ESBL-positive isolates were collected from the study but its in vitro activity against ESBL-producers has not been investi- hospitals. Carbapenem-resistant isolates (imipenem MIC N1 μg/mL, gated. Since CRE is an urgent problem in South Korea, as it is worldwide n = 24) were excluded from the study, and the remaining 213 isolates (Jeong et al., 2016), potential alternative options need to be studied to were tested for ESBL and AmpC β-lactamases. In phenotyping tests, reduce carbapenem use. In view of this, we have evaluated the in vitro 191 were only positive for ESBL and 10 only for AmpC β-lactamase, activity of flomoxef against ESBL-producing Enterobacteriaceae. while12werepositiveforboth.AmongtheESBL-only–positive isolates (n = 191), the number of isolates having CTX-M-1 and/or CTX-M-9 β β 2. Materials and methods group lactamase was 178. Of these, 2 had AmpC -lactamase concurrently (CMY, n = 2). Finally, 176 isolates were subjected to 2.1. Collection of ESBL-positive isolates the antibiotic susceptibility tests (E. coli, n =93andK. pneumoniae, n = 83). The sources of these isolates were: 89 urine, 54 respiratory fl fl This study was conducted at 3 university-affiliated hospitals secretion, 10 pus, 14 blood, 5 gastrointestinal uid, and 4 bile uid. β – (Kangnam Sacred Heart Hospital, Hallym University Sacred Heart Among the 22 AmpC -lactamase positive isolates from the phenotyp- β Hospital, and Wonju Severance Christian Hospital) in South Korea. ing test (ESBL and AmpC -lactamase co-producers, n =12andAmpC β – Bacteria were identified in the respective microbiology laboratories -lactamase only producers, n = 10), 11 isolates (E. coli, n = 8 and β using ViTek-2 (bioMérieux) or Microscan (Siemens Healthcare). K. pneumoniae, n = 3) were found to carry AmpC -lactamase gene Nonduplicated clinical ESBL-positive Klebsiella pneumoniae (ESBL-KP) (blaCMY, n =6andblaDHA, n = 5). The genotypic distributions of and ESBL-positive Escherichia coli (ESBL-EC) isolates were collected ESBL-EC and ESBL-KP were given in Table 1. between June and July 2016 and sent to a reference laboratory (Kangnam Sacred Heart Hospital) for further investigation. 3.2. Antimicrobial susceptibilities of the ESBL-producing E. coli and K. pneumoniae β 2.2. Detection of ESBL and AmpC -lactamase Amikacin had excellent activity (96.6% susceptible). The MICs of flomoxef against the 176 ESBL-producing isolates ranged from – ESBL phenotyping was performed using ceftazidime clavulanate ≤0.125 μg/mL to 128 μg/mL (MIC =0.5μg/mL and MIC = – 50 90 and/or cefotaxime clavulanate in combination with boronic acid versus 8 μg/mL). Rates of susceptibility to flomoxef and cefotetan were also ≥ ceftazidime and/or cefotaxime containing boronic acid. A 5-mm in- high (94.3% and 91.5%), and to cefoxitin, they were moderate (76.7%). β crease in zone diameter was considered positive. AmpC -lactamase About 65% of the isolates were susceptible to amoxicillin–clavulanate production was tested by cefoxitin and/or cefotetan containing boronic and piperacillin–tazobactam. The rates of susceptibility of the ESBL-EC ≥ acid versus cefoxitin and/or cefotetan; a 5-mm increase in zone diam- to all the tested antibiotics were greater than those of the ESBL-KP. eter was considered positive, as described (Song et al., 2007). Isolates Detailed data on the in vitro susceptibilities to all the tested antibiotics, not susceptible to cefotaxime were evaluated for having ESBL genes, and the MIC50 and MIC90 values of them are presented in Table 2. and polymerase chain reaction (PCR) amplification was performed for the blaCTX-M-1 group and blaCTX-M-9 group as described (Abdalhamid 3.3.