Diagnostic Microbiology and Infectious Disease 80 (2014) 233–238

Contents lists available at ScienceDirect

Diagnostic Microbiology and Infectious Disease journal homepage: www.elsevier.com/locate/diagmicrobio

Ceftazidime-avibactam and comparator agents tested against urinary tract isolates from a global surveillance program (2011) Robert K. Flamm a,⁎, Helio S. Sader a, David J. Farrell a, b, Ronald N. Jones a, c a b c

JMI Laboratories, North Liberty, IA 52317 USA Department of Laboratory Medicine and Pathobiology, University of Toronto, Canada Tufts University School of Medicine, Boston, MA 02111 USA

a r t i c l e

i n f o

Article history: Received 7 May 2014 Received in revised form 7 July 2014 Accepted 8 July 2014 Available online 24 July 2014 Keywords: Ceftazidime-avibactam UTI Surveillance

a b s t r a c t Ceftazidime-avibactam, a combination of ceftazidime and the non–β-lactam β-lactamase inhibitor avibactam, is in advanced clinical development. In this study, we report results of in vitro testing of ceftazidimeavibactam and comparator agents against a collection of urinary tract infection (UTI) isolates from the United States (USA), Europe and Mediterranean region (EMR), Latin America (LATAM), and the Asia-Pacific/South Africa regions (APAC). Clinical isolates (1 per patient episode) were collected from patients with a UTI during 2011. A total of 1797 isolates were collected from 159 medical centers. Isolates were processed at the medical centers and forwarded to a central monitoring laboratory for confirmatory identification and reference susceptibility testing. Ceftazidime-avibactam was highly active against Enterobacteriaceae and Pseudomonas aeruginosa. The MIC90 values for ceftazidime-avibactam against Enterobacteriaceae in the USA, EMR, and LATAM regions ranged from 0.25 to 0.5μg/mL. The MIC90 in the APAC was slightly elevated at 1μg/mL. A total of 6.1% (8/131) of Escherichia coli in the USA, 23.5% (43/183) in the EMR, 61.2% (30/49) in LATAM, and 75.0% (9/12) in APAC exhibited an extended-spectrum β-lactamase (ESBL) screen–positive phenotype. A total of 1.6% (2/129) of Klebsiella pneumoniae isolates in the USA were meropenem-non-susceptible (MIC ≥2μg/mL), but a rate of 10.3% (10/97) was observed in the EMR. All ESBL screen–positive phenotype and meropenemnon-susceptible E. coli and K. pneumoniae isolates exhibited a ceftazidime-avibactam MIC ≤4μg/mL. All isolates of P. aeruginosa in the USA and 80.9% (38/47) in the EMR were inhibited at a ceftazidime-avibactam MIC of ≤8μg/mL compared to 88.2% (15/17) and 61.7% (29/47) for ceftazidime alone. Ceftazidime-avibactam demonstrated wide in vitro activity against Gram-negative bacteria from patients with UTI including high potencies against multidrug-resistant organisms. © 2014 Elsevier Inc. All rights reserved.

1. Introduction Urinary tract infections (UTIs) are common in both the community and hospital settings (Foxman, 2010; Gupta et al., 2011). In the hospital environment, complicated UTIs may lead to increased mortality, thus emphasizing the need for the selection of appropriate initial therapy (Hooton et al., 2010; Platt et al., 1982). Wide variation exists in the choice of antimicrobial agents and duration of treatment for UTI (Gupta et al., 2011). Treatment decisions must factor concerns about bacterial resistance among uropathogens, drug availability and cost, expected efficacy, and a desire to limit the effect of the antimicrobial on normal bacterial flora (Foxman, 2010; Gupta et al., 2011; Hooton et al., 2010).

⁎ Corresponding author. Tel.: +1-319-665-3370; fax: +1-319-665-3371. E-mail address: robert-fl[email protected] (R.K. Flamm). http://dx.doi.org/10.1016/j.diagmicrobio.2014.07.005 0732-8893/© 2014 Elsevier Inc. All rights reserved.

Ceftazidime-avibactam is a combination agent consisting of the non–β-lactam β-lactamase inhibitor avibactam and the broad-spectrum cephalosporin, ceftazidime (Bebrone et al., 2010; Bonnefoy et al., 2004; Coleman, 2011; Stachyra et al., 2009, 2010). In this combination, avibactam protects ceftazidime from hydrolysis by β-lactamases, thus preserving antibacterial activity (Coleman, 2011; Stachyra et al., 2009, 2010). Ceftazidime-avibactam exhibits a wide activity against Gramnegative bacteria including those that produce Class A, C, and some D β-lactamases. Ceftazidime-avibactam administered at 500mg of ceftazidime and 125mg of avibactam every 8hours was shown to have efficacy and safety similar to imipenem-cilastatin (500mg every 6) in a Phase II study of UTI (NCT00690378) (Vazquez et al., 2012). Escherichia coli was the predominant uropathogen recovered from patients followed by other Enterobacteriaceae and Pseudomonas aeruginosa. Ceftazidime-avibactam is currently in Phase III clinical trials for treatment of UTI, complicated intra-abdominal infections, and hospitalized patients with nosocomial pneumonia. In this investigation, we evaluated the activity of ceftazidimeavibactam tested against uropathogens on a global scale. Ceftazidime-

234

R.K. Flamm et al. / Diagnostic Microbiology and Infectious Disease 80 (2014) 233–238

Table 1 Cumulative MIC distribution values for ceftazidime-avibactam when tested against selected UTI isolates from all regions (2011). Organism/resistant subset

No. of No. of isolates (cumulative %) inhibited at MIC (μg/mL) of: isolates ≤0.06 0.12 0.25 0.5 1

2

Enterobacteriaceae E. coli ESBL screen–positive phenotype K. pneumoniae ESBL screen–positive phenotype MER-non-susceptible (MIC, ≥2μg/mL) Klebsiella oxytoca M. morganii Citrobacter spp. Enterobacter spp. S. marcescens P. aeruginosa MER-non-susceptible (MIC, ≥4μg/mL) CAZ-non-susceptible (MIC, ≥16μg/mL) S. aureus β-Hemolytic streptococci

1297 375 90 254 84 12 42 127 176 159 67 80 26

4

640 (49.3) 364 (77.4) 178 (91.1) 244 (65.1) 96 (90.7) 30 (98.7) 34 (37.8) 31 (72.2) 20 (94.4)

64 (96.1) 4 (99.7) 4 (98.9)

23 (97.8) 0 (99.7) 0 (98.9)

14 (98.9) 0 (99.7) 0 (98.9)

3 (99.2) 1 (100.0) 1 (100.0)

103 (40.6) 10 (11.9) – 21 (50.0) 105 (82.7) 53 (30.1) 26 (16.4) 2 (3.0) – –

26

–

88 177

– –

8

16

≥32

0 (99.2) 0 (99.2) 11 (100.0) – – – – – –

MIC50 MIC90 0.12 0.06 0.12

0.25 0.12 0.25

86 (74.4) 25 (41.7)

33 (87.4) 20 (65.5)

18 (94.5) 15 (83.3)

6 (96.9) 6 (90.5)

7 (99.6) 7 (98.8)

1 (100.0) 1 (100.0)

– –

– –

– –

0.12 0.25

0.5 1

2 (16.7)

1 (25.0)

4 (58.3)

1 (66.7)

3 (91.7)

1 (100.0)

–

–

–

0.5

2

10 (73.8) 12 (92.1) 59 (63.6) 64 (56.6) 30 (47.8) – –

6 (88.1) 9 (99.2) 41 (86.9) 37 (79.9) 20 (77.6) 1 (1.3) –

0.06 0.06 0.12 0.12 0.25 2 8

0.5 0.12 0.5 1 1 32 N32

8

N32

– – 11 (6.2)

–

5 (100.0) – 1 (100.0) – 14 (94.9) 4 (97.2) 14 (88.7) 10 (95.0) 8 (89.6) 3 (94.0) 1 (2.5) 25 (33.8) – 1 (3.8) –

– – 18 (16.4) 147 (99.4)

1 (3.8) – 1 (100.0)

– – – – 1 (97.7) 1 (98.3) 5 (98.1) 0 (98.1) 1 (95.5) 0 (95.5) 24 (63.7) 10 (76.3) 4 (19.2) 3 (30.8) 3 (15.4) – –

4 (30.8) 12 (13.6) –

– – 0 (98.3) 0 (98.1) 0 (95.5) 6 (83.8) 6 (53.8)

– – – – 0 (98.3) 3 (100.0) 0 (98.1) 3 (100.0) 0 (95.5) 3 (100.0) 2 (86.3) 11 (100.0) 1 (57.7) 11 (100.0)

5 (50.0) 2 (57.7) 11 (100.0)

30 (47.7) 9 (58.0) 37 (100.0) 16 – – – 0.5

N32 0.5

CAZ = ceftazidime; MER = meropenem.

avibactam and comparator agents were tested against a contemporary collection of UTI isolates from the United States (USA), Europe and Mediterranean (EMR), Latin America (LATAM), and the Asia-Pacific and South Africa (APAC) regions. 2. Materials and methods 2.1. Organism collection A total of 1797 isolates were collected during 2011 and identified as UTI pathogens (including pathogens from both complicated and uncomplicated infections) based on the infection site and/or specimen type recorded by the participant laboratory. Isolates were collected from patients at 159 medical centers. In the USA, 821 isolates were contributed from 67 medical centers distributed across all 9 census regions. A total of 610 isolates were contributed from 46 medical centers in the EMR (17 EU countries [included Belgium, Bulgaria, Czech Republic, France, Germany, Greece, Hungary, Ireland, Italy, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, and the United Kingdom {UK}]) and 3 additional countries (Israel, Russia, and Turkey). From the LATAM (Argentina, Brazil, Chile, Columbia, Mexico, Panama, and Venezuela) and APAC (Australia, China, India, Korea, Malaysia, Singapore, and Thailand, Hong Kong, and South Africa) regions, 183 isolates (each region) were submitted from 16 and 30 medical centers, respectively. Isolates were processed at the respective medical centers and forwarded to a coordinating laboratory (JMI Laboratories, North Liberty, IA, USA; Australian isolates only, South Australia Pathology, Women's & Children's Hospital, Adelaide, Australia) for confirmatory identification and reference susceptibility testing using Clinical and Laboratory Standards Institute (CLSI, 2012, 2014) methods. Avibactam was tested at a fixed concentration of 4μg/mL. 2.2. Susceptibility testing Ceftazidime-avibactam and comparator agents were susceptibility tested by CLSI reference broth microdilution methods (CLSI, 2012).

CLSI interpretative criteria were applied per M100-S24 (CLSI, 2014). European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretations were based on the EUCAST breakpoint tables for interpretation of MIC results (EUCAST, 2014). An extendedspectrum β-lactamase (ESBL) screen–positive phenotype was defined as an MIC of ≥2μg/mL for ceftazidime or ceftriaxone or aztreonam (CLSI, 2014). Concurrent quality control (QC) testing was performed including the following strains: Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Streptococcus pneumoniae ATCC 49619, E. coli ATCC 25922 and 35218, and Klebsiella pneumoniae ATCC 700603, and all QC results were within published ranges (CLSI, 2014). 3. Results 3.1. Antimicrobial profile of Enterobacteriaceae Ceftazidime-avibactam was highly active against all tested Enterobacteriaceae from UTI with MIC50 and MIC90 values of 0.12 and 0.25μg/mL (Table 1). The MIC90 value for ceftazidime tested alone against these organisms was 128-fold higher (32μg/mL) than for ceftazidime-avibactam. Enterobacteriaceae isolates from the APAC region exhibited the highest ceftazidime-avibactam MIC90 of 1μg/mL (N32μg/mL for ceftazidime alone; Table 2). In the USA, all ceftazidime-avibactam MIC values for Enterobacteriaceae were ≤2μg/mL; 99.4 and 99.2% of values in the EMR and LATAM were ≤4μg/mL, respectively (CLSI susceptibility breakpoint for ceftazidime when tested alone; data not shown). Ciprofloxacin resistance among all Enterobacteriaceae was 23.5/26.1% (CLSI/EUCAST), and meropenem resistance was 1.9/1.0% (data not shown). Regional ciprofloxacin resistance varied from a low of 11.1/13.4% (CLSI/EUCAST) in the USA to a high of 40.0/45.4% in LATAM (Table 2). Meropenem resistance varied from a low of 0.8/0.0% in LATAM to a high of 3.7/2.9% in APAC (Table 2). The MIC50 and MIC90 for ceftazidime-avibactam tested against all E. coli from UTI were 0.06 and 0.12μg/mL, respectively (Table 1), compared to 0.25 and 32μg/mL for ceftazidime alone (data not shown). Regional ceftazidime-avibactam MIC90 values were 0.12μg/mL (USA), 0.25μg/mL (EMR), 0.25μg/mL (LATAM), and 0.5μg/mL (APAC) (Table 2). Overall, there were 24.0% ESBL screen–positive phenotype E. coli (Table 1). When analyzed by region, 6.1% (8/131) of E. coli in the USA, 23.5% (43/183) in the EMR, 61.2% (30/ 49) in LATAM, and 75.0% (9/12) in APAC showed an ESBL screen–positive phenotype (Table 2). Ciprofloxacin resistance among all E. coli was 37.9/37.9% (CLSI/EUCAST), and there was no meropenem resistance (data not shown). Regional ciprofloxacin resistance rates varied from a low of 22.1/22.1% in the USA (CLSI/EUCAST) to a high of 75.0/75.0% in APAC (Table 2). The MIC90 for ceftazidime-avibactam tested against all Klebsiella pneumoniae was N64fold lower than for ceftazidime alone (0.5μg/mL compared to N32μg/mL; data not shown).

R.K. Flamm et al. / Diagnostic Microbiology and Infectious Disease 80 (2014) 233–238 Regional ceftazidime-avibactam MIC90 values were 0.25μg/mL (USA), 1μg/mL (EMR), and 0.25μg/mL (LATAM) (Table 2). The overall percentage of ESBL screen–positive phenotype K. pneumoniae was 33.1% (Table 1). A total of 6.2% (8/129) of K. pneumoniae in the USA, 61.9% (60/97) in the EMR, 60.0% (15/25) in LATAM, and 33.3% (1/3) in APAC showed an ESBL screen–positive phenotype. Ciprofloxacin resistance among all K. pneumoniae was 26.4/29.1% (CLSI/EUCAST), and meropenem resistance was 4.3/3.2% (data not shown). Regional ciprofloxacin resistance for K. pneumoniae varied from 5.4/5.4% in the USA to 55.7/57.7% in the EMR (Table 2). There were no meropenem-resistant K. pneumoniae in LATAM and APAC; however, in the USA, the rate was 1.6/0.8%, and in the EMR, it was 9.3/ 7.2% (Table 2). All meropenem-non-susceptible K. pneumoniae strains in the USA and EMR exhibited a ceftazidime-avibactam MIC ≤4μg/m (Table 1). Ceftazidime-avibactam showed potent activity against other members of the Enterobacteriaceae family including Citrobacter spp. (MIC50 and MIC90, 0.12 and 0.5μg/mL, respectively), Enterobacter spp. (MIC50 and MIC90, 0.12 and 1μg/mL), Morganella morganii (MIC50 and MIC90, 0.06 and 0.12μg/mL), and Serratia marcescens (MIC50 and MIC90, 0.25 and 1μg/mL; Table 1). However, regional susceptibility for ceftazidime varied greatly. For Citrobacter spp., susceptibility ranged from 63.6% (CLSI criteria) in LATAM to 79.6% (USA; Table 2), and regional ceftazidime susceptibility for Enterobacter spp. ranged from 17.6% (CLSI criteria) in LATAM to 91.0% in the USA (Table 2).

3.2. Antimicrobial profile of P. aeruginosa Against all P. aeruginosa strains, ceftazidime-avibactam exhibited an MIC50 that was 2fold lower than ceftazidime alone (2 versus 4μg/mL; Table 1; data not shown). The MIC90 value for both ceftazidime-avibactam and ceftazidime alone was 32μg/mL (Table 1, data not shown). A total of 83.8% (ceftazidime-avibactam) and 67.5% (ceftazidime alone) of isolates exhibited MIC values of ≤8μg/mL (Table 1; data not shown). Ceftazidimeavibactam was more active against meropenem-non-susceptible and ceftazidime-nonsusceptible strains than ceftazidime alone (Table 1). The MIC50 and MIC90 values for ceftazidime-avibactam against meropenem-non-susceptible P. aeruginosa were 8 and N32μg/mL, while for ceftazidime alone, the values were 32 and N32μg/mL, respectively (Table 1, data not shown). A total of 53.8% of meropenem-non-susceptible and 50.0% of ceftazidime-non-susceptible isolates showed an MIC value of ≤8μg/mL, respectively, for ceftazidime-avibactam (Table 1). All P. aeruginosa isolates in the USA and 80.9% (38/47) in the EMR were inhibited by a ceftazidime-avibactam MIC of ≤8μg/mL compared to 88.2% (15/17) and 61.7% (29/47), respectively, for ceftazidime alone (data not shown). In the EMR, all 9 P. aeruginosa isolates with ceftazidime-avibactam MIC values ≥32μg/mL were from Romania (5), Portugal (3), and Poland (1), indicating potentially significant national differences for these resistant isolates.

3.3. Antimicrobial profile of Gram-positive bacteria Ceftazidime-avibactam and ceftazidime alone exhibited similar activity against β-hemolytic streptococci (MIC 50 and MIC90 , 0.5 and 0.5μg/mL, respectively) and poor activity against S. aureus (MIC50 and MIC90 , 16 and N32μg/mL; Table 1, data not shown).

4. Discussion Ceftazidime-avibactam was highly active against Gram-negative bacteria isolated from UTI in a global surveillance program conducted during 2011. The MIC50 and MIC90 for Enterobacteriaceae in this study were 0.12 and 0.25μg/mL, respectively. This level of potency for ceftazidime-avibactam against UTI isolates is similar to that reported for bloodstream, respiratory tract, and soft tissue infection isolates by Sader et al. (2014) for a collection of 8,640 Enterobacteriaceae from USA medical centers. Among the Enterobacteriaceae, ceftazidime-avibactam demonstrated activity against a variety of multidrug-resistant (MDR) bacteria, including ESBL- and KPC-phenotype strains. A total of 99.2 and 97.8% of all Enterobacteriaceae exhibited a ceftazidime-avibactam MIC of ≤4μg/mL (CLSI susceptible breakpoint for ceftazidime alone) or ≤1μg/mL (EUCAST susceptible breakpoint for ceftazidime alone), a marked improvement over the in vitro activity of ceftazidime (78.3%). A high level of in vitro activity for the isolates from UTI infections in this study was demonstrated by ceftazidime-avibactam MIC90 values for ESBL screen–positive phenotype E. coli and ESBL screen–positive phenotype K. pneumoniae of 0.25μg/mL and 1μg/mL, respectively. The overall high level of potency against ESBL screen–positive phenotype strains shown was similar to that previously documented against a collection of USA isolates from a broad range of infection types (Sader et al., 2014).

235

The ESBL screen–positive phenotype for E. coli and K. pneumoniae in this study may have included strains resistant to third-generation cephalosporins due to increased cephalosporinase or carbapenemase activity. However, the majority of ESBL screen–positive phenotype strains would be expected to confirm as ESBL as shown by the work of Castanheira et al. (2014) where 90% of ESBL screen–positive isolates were later confirmed with a microarray-based method. Ceftazidime-avibactam demonstrated potent in vitro activity against P. aeruginosa isolated from UTI infections. Ceftazidimeavibactam was more active than ceftazidime when tested alone against P. aeruginosa strains including those isolates that were non-susceptible to meropenem. In a previous study from the USA, 96.9% of P. aeruginosa displayed a ceftazidime-avibactam MIC value ≤8μg/mL compared to 83.2% for ceftazidime alone (Sader et al., 2014). In this global UTI study, 83.8% of P. aeruginosa exhibited a ceftazidime-avibactam MIC value ≤8μg/mL while only 67.5% for ceftazidime. Although molecular mechanisms of resistance were not determined in this global surveillance study, it is noteworthy that isolates of P. aeruginosa from patients in some countries of Europe in 2011 were characterized by a relatively high prevalence of carriage of the metallo-β-lactamase gene, VIM-2 (Castanheira et al 2014). This may account for some of the observed regional differences in susceptibility among P. aeruginosa to β-lactam agents, including the ceftazidime-avibactam combination. Regional variations in susceptibility occurred for a number of comparison agents. If one were to apply for analysis purposes either the EUCAST or CLSI susceptible breakpoints for Enterobacteriaceae of ceftazidime alone of 1 and 4μg/mL, respectively, to ceftazidimeavibactam, more than 90% of isolates would be categorized as susceptible. Meropenem also demonstrated greater than 90% susceptibility rates in all regions. For P. aeruginosa, no agent exhibited 90% or greater susceptibility rates in any region, demonstrating the challenge that MDR strains present. Ciprofloxacin regional susceptibility ranged from 51.1% to 64.7%; meropenem susceptibility, from 61.5% to 88.2%; cefepime susceptibility, from 61.5% to 88.2%; and piperacillin-tazobactam, from 53.8% to 76.5%. Ceftazidime-avibactam activity compared very favorably to these comparators with regional MIC values ≤8μg/mL (the CLSI and EUCAST susceptible breakpoint for ceftazidime alone for P. aeruginosa) ranging from 61.7% to 100.0%. Limitations of the current study include 1) that it was conducted during 2011 and the epidemiology of microorganisms in UTI may have changed in the intervening time; 2) there are incomplete epidemiologic data distinguishing between complicated and uncomplicated UTI and nosocomial versus community-acquired infections; and 3) numbers of isolates from individual medical centers and the number of medical centers in the LATAM and APAC were relatively low; thus, the calculation of the percentage of resistance may have been overestimated due to a small denominator. Surveillance studies at the local level enrolling a higher number of centers and isolates with more definitive demographic information would be highly desirable. The efficacy of ceftazidime-avibactam against resistant organisms has been shown in various animal models of infection (Crandon et al., 2012; Endimiani et al., 2011; Zhanel et al., 2013). For example, in a sepsis and a neutropenic thigh model, ceftazidime-avibactam was shown to be effective against highly resistant KPC-2–producing K. pneumoniae isolates (Endimiani et al., 2011). In a mouse thigh model of infection (immunocompetent and neutropenic), ceftazidime-avibactam was shown to be effective against multiple P. aeruginosa strains including ceftazidime-non-susceptible strains (Crandon et al., 2012). Doses of ceftazidime-avibactam, mimicking or resembling pharmacologic human doses, provided predictable activity against isolates with MICs of ≤16μg/mL (Crandon et al., 2012). With its activity against resistant organisms as described above in animal models and activity in various in

236

Table 2 Activity by geographic region for ceftazidime-avibactam and comparator agents when tested against selected UTI Gram-negative clinical isolates (2011). Antimicrobial agent (N)

USA

MIC50b (N=560) 0.06 0.12 ≤0.5 ≤0.03 ≤0.06 2 (N=131) 0.06 0.12 ≤0.5 ≤0.03 ≤0.06 2 (N=8c) 0.12 4 4 N4 ≤0.06 4 (N=129) 0.06 0.12 ≤0.5 ≤0.03 ≤0.06 2 (N=8c) 0.25 16 16 N4 ≤0.06 8 (N=67) 0.12 0.25 ≤0.5 ≤0.03 ≤0.06 4 (N=93) 0.12 0.25 ≤0.5 ≤0.03 ≤0.06 2 (N=51) 0.06 0.12

EUCASTa

MIC90b

%S/%R

%S/%R

0.25 2 ≤0.5 N4 ≤0.06 8

-/-/ 91.1/8.4 97.5/1.4 86.6/11.1 98.8/0.9 94.3/3.2

-/-/ 89.5/8.9 93.9/2.9 85.0/13.4 99.1/0.2 92.7/5.7

0.12 0.5 ≤0.5 N4 ≤0.06 4

-/-/ 96.9/2.3 97.7/1.5 77.9/22.1 100.0/0.0 96.9/1.5

-/-/ 94.7/3.1 93.9/3.1 77.9/22.1 100.0/0.0 94.7/3.1

-

-/50.0/37.5 62.5/25.0 37.5/62.5 100.0/0.0 87.5/0.0

-/12.5/50.0 12. 5/50.0 37.5/62.5 100.0/0.0 62.5/12.5

0.25 0.5 ≤0.5 0.5 ≤0.06 8 -

-/-/ 93.8/5.4 95.3/3.1 94.6/5.4 98.5/1.6 96.9/3.1

-/-/ 93.8/6.2 93.8/4.7 92.2/5.4 98.5/0.8 95.3/3.1

-/0.0/87.5 25.0/50.0 25.0/75.0 75.0/25.0 50.0/50.0

-/0.0/100.0 0.0/75.0 25.0/75.0 75.0/12.5 50.0/50.0

0.25 4 ≤0.5 0.25 ≤0.06 8

-/-/ 91.0/9.0 95.5/3.0 92.5/6.0 95.5/3.0 94.0/4.5

-/-/ 88.1/9.0 91.0/4.5 92.5/7.5 97.0/0.0 92.5/6.0

0.25 N32 1 0.25 ≤0.06 64

-/-/ 79.6/20.4 97.8/0.0 93.5/3.2 97.8/1.1 82.8/6.5

-/-/ 79.6/20.4 92.5/3.2 92.5/6.5 98.9/0.0 79.6/17.2

0.25 32

-/-/ 78.4/19.6

-/-/ 72.5/21.6

MIC50b (N=470) 0.06 0.25 ≤0.5 0.06 ≤0.06 2 (N=183) 0.06 0.25 ≤0.5 ≤0.03 ≤0.06 2 (N=43) 0.12 32 N16 N4 ≤0.06 8 (N=97) 0.12 32 8 N4 ≤0.06 8 (N=60) 0.25 N32 N16 N4 ≤0.06 32 (N=44) 0.12 0.5 ≤0.5 ≤0.03 ≤0.06 4 (N=37) 0.12 0.25 ≤0.5 ≤0.03 ≤0.06 2 (N=36) ≤0.03 0.25

LATAM CLSIa

EUCASTa

MIC90b

%S/%R

%S/%R

0.5 N32 N16 N4 0.12 64

-/-/ 73.2/23.6 80.9/18.3 65.5/32.3 97.0/2.8 82.3/9.0

-/-/ 69.6/26.8 74.7/21.3 63.2/34.5 97.2/1.7 78.9/17.7

0.25 32 N16 N4 ≤0.06 16

-/-/ 80.9/15.8 84.2/14.2 60.7/39.3 100.0/0.0 92.3/2.2

-/-/ 77.0/19.1 78.7/16.9 59.6/39.3 100.0/0.0 87.9/7.7

0.25 N32 N16 N4 ≤0.06 64

-/18.6/67.4 32.6/60.5 16.3/83.7 100.0/0.0 76.7/4.7

-/2.3/81.4 11.6/72.1 16.3/83.7 100.0/0.0 65.1/23.3

1 N32 N16 N4 2 N64

-/-/ 42.3/53.6 50.5/48.5 42.3/55.7 89.7/9.3 56.7/23.7

-/-/ 40.2/57.7 41.2/53.6 41.2/57.7 90.7/7.2 50.5/43.3

1 N32 N16 N4 N8 N64

-/6.7/86.7 20.0/78.3 18.3/78.3 83.3/15.0 35.0/35.0

-/3.3/93.3 6.7/86.7 16.7/81.7 85.0/11.7 28.3/65.0

0.5 N32 8 N4 0.12 N64

-/-/ 63.6/34.1 93.2/6.8 77.3/18.2 97.7/2.3 72.7/15.9

-/-/ 61.4/36.4 79.5/13.6 72.7/22.7 97.7/2.3 72.7/27.3

0.5 32 8 N4 ≤0.06 64

-/-/ 78.4/18.9 91.9/8.1 86.5/10.8 100.0/0.0

-/-/ 75.7/21.6 89.2/10.8 86.5/13.5 100.0/0.0

0.12 8

-/-/ 88.9/5.6

-/-/ 80.6/11.1

MIC50b (N=130) 0.12 2 ≤0.5 0.25 ≤0.06 4 (N=49) 0.06 8 N16 N4 ≤0.06 4 (N=30) 0.12 16 N16 N4 ≤0.06 8 (N=25) 0.12 4 8 1 ≤0.06 8 (N=15) 0.12 16 N16 2 ≤0.06 16 (N=17) 0.25 32 1 0.25 ≤0.06 16 (N=11) 0.12 0.5 ≤0.5 ≤0.03 ≤0.06 2 (N=11) ≤0.03 0.25

APAC CLSIa

EUCASTa

MIC90b

%S/%R

%S/%R

0.25 N32 N16 N4 ≤0.06 32

-/-/ 55.4/38.5 67.7/27.7 54.6/40.0 99.2/0.8 83.8/4.6

-/-/ 46.9/44.6 56.9/39.2 51.5/45.4 99.2/0.0 73.8/16.2

0.25 32 N16 N4 ≤0.06 16

-/-/ 44.9/44.9 46.9/51.0 34.7/65.3 100.0/0.0 91.8/2.0

-/-/ 42.9/55.1 38.8/59.2 34.7/65.3 100.0/0.0 81.6/8.2

0.25 32 N16 N4 ≤0.06 32

-/10.0/73.3 13.3/83.3 3.3/96.7 100.0/0.0 86.7/3.3

-/6.7/90.0 0.0/96.7 3.3/96.7 100.0/0.0 70.0/13.3

0.25 N32 N16 N4 ≤0.06 N64

-/-/ 64.0/32.0 60.0/32.0 56.0/24.0 100.0/0.0 76.0/12.0

-/-/ 40.0/36.0 48.0/52.0 48.0/44.0 100.0/0.0 64.0/24.0

0.25 N32 N16 N4 ≤0.06 N64

-/40.0/53.3 33.3/53.3 26.7/40.0 100.0/0.0 60.0/20.0

-/0.0/60.0 13.3/86.7 13.3/73.3 100.0/0.0 46.7/40.0

1 N32 N16 N4 0.12 64

-/-/ 17.6/76.5 82.4/11.8 64.7/35.3 100.0/0.0 52.9/5.9

-/-/ 11.8/82.4 58.8/23.5 58.8/35.3 100.0/0.0 29.4/47.1

0.5 N32 1 0.25 ≤0.06 32

-/-/ 63.6/27.3 90.9/9.1 90.9/9.1 90.9/9.1 81.8/9.1

-/-/ 54.5/36.4 90.9/9.1 90.9/9.1 90.9/0.0 72.7/18.2

0.12 2

-/-/ 90.9/9.1

-/-/ 72.7/9.1

MIC50b (N=137) 0.12 0.5 ≤0.5 0.12 0.06 2 (N=12) 0.12 4 16 N4 ≤0.06 4 (N=9c) 0.12 16 N16 N4 ≤0.06 8 (N=3c) 0.06 0.12 ≤0.5 ≤0.03 ≤0.06 4 (N=1c) (N=31) 0.25 16 ≤0.5 0.12 ≤0.06 8 (N=35) 0.12 0.5 ≤0.5 0.06 ≤0.06 4 (N=29) 0.06 0.12

CLSIa

EUCASTa

MIC90b

%S/%R

%S/%R

1 N32 N16 N4 0.25 64

-/-/ 65.0/32.8 79.6/16.8 68.6/28.5 94.9/3.7 81.0/9.5

-/-/ 58.4/35.0 73.7/23.4 67.2/31.4 96.4/2.9 75.9/19.0

0.5 N32 N16 N4 ≤0.06 16

50.0/41.7 41.7/41.7 25.0/75.0 100.0/0.0 91.7/8.3

25.0/50.0 25.0/75.0 25.0/75.0 100.0/0.0 75.0/8.3

-

-/33.3/55.6 22.2/55.6 22.2/77.8 100.0/0.0 88.9/11.1

-/0.0/66.7 0.0/100.0 22.2/77.8 100.0/0.0 77.8/11.1

-

-

-

-

-/0.0/100.0 100.0/0.0 100.0/0.0 100.0/0.0 100.0/0.0

-/0.0/100.0 0.0/100.0 100.0/0.0 100.0/0.0 100.0/0.0

2 N32 N16 N4 1 N64

-/41.9/58.1 71.0/25.8 58.1/38.7 90.3/6.5 58.1/29.0

-/35.5/58.1 67.7/29.0 54.8/41.9 93.5/6.5 51.6/41.9

0.5 N32 N16 4 ≤0.06 64

-/-/ 65.7/34.3 82.9/14.3 80.0/17.1 94.3/2.9 77.1//2.9

-/-/ 62.9/34.3 77.1/20.0 80.0/20.0 97.1/0.0 74.3/22.9

0.06 16

-/-/ 82.8/13.8

-/-/ 72.4/17.2

R.K. Flamm et al. / Diagnostic Microbiology and Infectious Disease 80 (2014) 233–238

Enterobacteriaceae Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam E. coli Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam ESBL screen–positive Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam K. pneumoniae Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam ESBL screen–positive Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam Enterobacter spp. Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam Citrobacter spp. Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam M. morganii Ceftazidime-avibactam Ceftazidime

EMR CLSIa

93.1/0.0 65.5/31.0 100.0/0.0 93.1/0.0

-

%S/%R

100.0/0.0 69.0/24.1 100.0/0.0 100.0/0.0

%S/%R

237

vitro studies (including the current study), ceftazidime-avibactam has shown that it may have a potential role for therapy of UTI infections where MDR Gram-negative pathogens are a major concern (Crandon et al., 2012; Endimiani et al., 2011; Flamm et al., 2013; Lagace-Wiens et al., 2011; Levasseur et al., 2012; Livermore et al., 2011; Mushtaq et al., 2010; Sader et al., 2014; Zhanel et al., 2013).

16 32 N16 N4 N8 N64

16 N4 0.12 2

-/-/ 61.7/38.3 66.0/34.0 51.1/48.9 61.7/23.4 57.4/42.6 -/-/ 61.7/31.9 66.0/21.3 51.1/44.7 61.7/29.8 57.4/25.5

MIC90 MIC50

≤0.5 N4 ≤0.06 ≤0.5 (N=13) 2 8 8 0.5 2 16 100.0/0.0 80.6/8.3 100.0/0.0 100.0/0.0

%S/%R %S/%R

EUCAST CLSI

32 32 N16 N4 N8 N64 -/-/ 88.2/11.8 88.2/11.8 52.9/35.3 88.2/5.9 76.5/23.5 -/-/ 88.2/11.8 88.2/5.9 64.7/35.3 88.2/11.8 76.5/11.8 4 32 16 N4 8 N64

MIC90 MIC50

≤0.5 ≤0.03 ≤0.06 ≤0.5 (N=47) 2 4 8 0.5 0.5 16 96.1/0.0 62.7/31.4 100.0/0.0 98.0/2.0

%S/%R %S/%R

100.0/0.0 68.6/23.5 100.0/0.0 98.0/2.0 ≤0.5 N4 0.12 2

b

EUCAST

Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam P. aeruginosa Ceftazidime-avibactam Ceftazidime Cefepime Ciprofloxacin Meropenem Piperacillin/tazobactam

MIC90 MIC50

b

≤0.5 ≤0.03 ≤0.06 ≤0.5 (N=17) 2 2 4 0.5 0.25 8

b

CLSI

≤0.5 1 0.12 2

b

100.0/0.0 91.7/5.6 100.0/0.0 100.0/0.0

b

LATAM a a

EMR a a

USA Antimicrobial agent (N)

Table 2 (continued)

S=susceptible and R=resistant. a Criteria as published by the CLSI (2014) and EUCAST (2014). As there are currently no established susceptibility criteria for ceftazidime avibactam, no susceptibility interpretation was provided. b Units in μg/mL. c Susceptibility values were not presented when the number of isolates was b10.

-/-/ 61.5/38.5 61.5/38.5 53.8/38.5 61.5/30.8 53.8/46.2 -/-/ 61.5/23.1 61.5/23.1 61.5/38.5 61.5/30.8 53.8/15.4

EUCAST

b

CLSI

1 N4 0.12 4 81.8/8.2 27.3/72.7 100.0/0.0 100.0/0.0 81.8//0.0 27.3/63.6 100.0/0.0 100.0/0.0

MIC50 %S/%R %S/%R

APAC a a

Acknowledgment

≤0.5 0.06 0.12 ≤0.5 (N=3c) 1 4 2 0.12 0.25 8

b

MIC90

b

CLSIa

EUCASTa

R.K. Flamm et al. / Diagnostic Microbiology and Infectious Disease 80 (2014) 233–238

This study was funded by AstraZeneca, and JMI Laboratories received compensation fees for services in relation to preparing the manuscript, also funded by AstraZeneca. This work was presented in part in abstract form at the 53rd Interscience Conference of Antimicrobial Agents and Chemotherapy, 2013.

References Bebrone C, Lassaux P, Vercheval L, Sohier JS, Jehaes A, Sauvage E, et al. Current challenges in antimicrobial chemotherapy: focus on ss-lactamase inhibition. Drugs 2010;70:651–79. Bonnefoy A, Dupuis-Hamelin C, Steier V, Delachaume C, Seys C, Stachyra T, et al. In vitro activity of AVE1330A, an innovative broad-spectrum non-β-lactam β-lactamase inhibitor. J Antimicrob Chemother 2004;54:410–7. Castanheira M, Farrell SE, Krause KM, Jones RN, Sader HS. Contemporary diversity of β-lactamases among Enterobacteriaceae in the nine United States census regions and ceftazidime-avibactam activity tested against isolates producing the most prevalent β-lactamase groups. Antimicrob Agents Chemother 2014; 58:833–88. Clinical and Laboratory Standards Institute (CLSI). M07-A9. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard. ninth ed. Wayne, PA: CLSI; 2012. Clinical and Laboratory Standards Institute (CLSI). M100-S24. Performance standards for antimicrobial susceptibility testing: 24th informational supplement. Wayne, PA: CLSI; 2014. Coleman K. Diazabicyclooctanes: a potent new class of non-β-lactam β-lactamase inhibitors. Curr Opin Microbiol 2011;14:550–5. Crandon JL, Schuck VJ, Banevicius MA, Beaudoin ME, Nichols WW, Tanudra MA, et al. Comparative in vitro and in vivo efficacies of human simulated doses of ceftazidime and ceftazidime-avibactam against Pseudomonas aeruginosa. Antimicrob Agents Chemother 2012;56:6137–46. Endimiani A, Hujer KM, Hujer AM, Pulse ME, Weiss WJ, Bonomo RA. Evaluation of ceftazidime and NXL104 in two murine models of infection due to KPCproducing Klebsiella pneumoniae. Antimicrob Agents Chemother 2011;55: 82–5. EUCAST Breakpoint tables for interpretation of MICs and zone diameters. Version 4. 0. January 2014. Available at http://www.eucast.org/clinical_breakpoints/. [Accessed January 2014]. Flamm RK, Stone GG, Sader HS, Jones RN, Nichols WW. Avibactam reverts the ceftazidime MIC90 of European Gram-negative bacterial clinical isolates to the epidemiological cut-off value. J Chemother 2013. [1973947813Y0000000145, Epub ahead of print]. Foxman B. The epidemiology of urinary tract infection. Nat Rev Urol 2010;7:653–60. Gupta K, Hooton TM, Naber KG, Wullt B, Colgan R, Miller LG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis 2011;52:e103–20. Hooton TM, Bradley SF, Cardenas DD, Colgan R, Geerlings SE, Rice JC, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clin Infect Dis 2010;50:625–63. Lagace-Wiens PR, Tailor F, Simner P, DeCorby M, Karlowsky JA, Walkty A, et al. Activity of NXL104 in combination with β-lactams against genetically characterized Escherichia coli and Klebsiella pneumoniae isolates producing class A extendedspectrum b-lactamases and class C b-lactamases. Antimicrob Agents Chemother 2011;55:2434–7. Levasseur P, Girard AM, Claudon M, Goossens H, Black MT, Coleman K, et al. In vitro antibacterial activity of the ceftazidime-avibactam (NXL104) combination against Pseudomonas aeruginosa clinical isolates. Antimicrob Agents Chemother 2012;56: 1606–8. Livermore DM, Mushtaq S, Warner M, Zhang J, Maharjan S, Doumith M, et al. Activities of NXL104 combinations with ceftazidime and aztreonam against carbapenemase-producing Enterobacteriaceae. Antimicrob Agents Chemother 2011;55: 390–4. Mushtaq S, Warner M, Livermore DM. In vitro activity of ceftazidime+NXL104 against Pseudomonas aeruginosa and other non-fermenters. J Antimicrob Chemother 2010; 65:2376–81.

238

R.K. Flamm et al. / Diagnostic Microbiology and Infectious Disease 80 (2014) 233–238

Platt R, Polk BF, Murdock B, Rosner B. Mortality associated with nosocomial urinarytract infection. N Engl J Med 1982;307:637–42. Sader HS, Castanheira M, Flamm RK, Farrell DJ, Jones RN. Antimicrobial activity of ceftazidime-avibactam against gram-negative organisms collected from U.S. medical centers in 2012. Antimicrob Agents Chemother 2014;58:1684–92. Stachyra T, Levasseur P, Pechereau MC, Girard AM, Claudon M, Miossec C, et al. In vitro activity of the β-lactamase inhibitor NXL104 against KPC-2 carbapenemase and Enterobacteriaceae expressing KPC carbapenemases. J Antimicrob Chemother 2009;64:326–9. Stachyra T, Pechereau MC, Bruneau JM, Claudon M, Frere JM, Miossec C, et al. Mechanistic studies of the inactivation of TEM-1 and P99 by NXL104, a novel

non-b-lactam b-lactamase inhibitor. Antimicrob Agents Chemother 2010;54: 5132–8. Vazquez JA, Gonzalez Patzan LD, Stricklin D, Duttaroy DD, Kreidly Z, Lipka J, et al. Efficacy and safety of ceftazidime-avibactam versus imipenem-cilastatin in the treatment of complicated urinary tract infections, including acute pyelonephritis, in hospitalized adults: results of a prospective, investigator-blinded, randomized study. Curr Med Res Opin 2012;28:1921–31. Zhanel GG, Lawson CD, Adam H, Schweizer F, Zelenitsky S, Lagace-Wiens PR, et al. Ceftazidime-avibactam: a novel cephalosporin/β-lactamase inhibitor combination. Drugs 2013;73:159–77.