scholarly journals Multicenter Evaluation of MIC Distributions for Epidemiologic Cutoff Value Definition To Detect Amphotericin B, Posaconazole, and Itraconazole Resistance among the Most Clinically Relevant Species of Mucorales

2015 ◽  
Vol 59 (3) ◽  
pp. 1745-1750 ◽  
Author(s):  
A. Espinel-Ingroff ◽  
A. Chakrabarti ◽  
A. Chowdhary ◽  
S. Cordoba ◽  
E. Dannaoui ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Acquired Resistance ◽  
The United States ◽  
Resistance Mechanisms ◽  
Wild Type ◽  
Content Type ◽  
Syncephalastrum Racemosum ◽  
Mucor Indicus ◽  
Clinical Breakpoints ◽  
Lichtheimia Corymbifera

ABSTRACTClinical breakpoints (CBPs) have not been established for theMucoralesand any antifungal agent. In lieu of CBPs, epidemiologic cutoff values (ECVs) are proposed for amphotericin B, posaconazole, and itraconazole and fourMucoralesspecies. Wild-type (WT) MIC distributions (organisms in a species-drug combination with no detectable acquired resistance mechanisms) were defined with available pooled CLSI MICs from 14 laboratories (Argentina, Australia, Canada, Europe, India, Mexico, and the United States) as follows: 10Apophysomyces variabilis, 32Cunninghamella bertholletiae, 136Lichtheimia corymbifera, 10Mucor indicus, 123M. circinelloides, 19M. ramosissimus, 349Rhizopus arrhizus, 146R. microsporus, 33Rhizomucor pusillus, and 36Syncephalastrum racemosumisolates. CLSI broth microdilution MICs were aggregated for the analyses. ECVs comprising ≥95% and ≥97.5% of the modeled populations were as follows: amphotericin B ECVs forL. corymbiferawere 1 and 2 μg/ml, those forM. circinelloideswere 1 and 2 μg/ml, those forR. arrhizuswere 2 and 4 μg/ml, and those forR. microsporuswere 2 and 2 μg/ml, respectively; posaconazole ECVs forL. corymbiferawere 1 and 2, those forM. circinelloideswere 4 and 4, those forR. arrhizuswere 1 and 2, and those forR. microsporuswere 1 and 2, respectively; both itraconazole ECVs forR. arrhizuswere 2 μg/ml. ECVs may aid in detecting emerging resistance or isolates with reduced susceptibility (non-WT MICs) to the agents evaluated.

scholarly journals Wild-Type MIC Distributions and Epidemiological Cutoff Values for Amphotericin B and Aspergillus spp. for the CLSI Broth Microdilution Method (M38-A2 Document)

2011 ◽  
Vol 55 (11) ◽  
pp. 5150-5154 ◽  
Author(s):  
A. Espinel-Ingroff ◽  
M. Cuenca-Estrella ◽  
A. Fothergill ◽  
J. Fuller ◽  
M. Ghannoum ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Acquired Resistance ◽  
The United States ◽  
Resistance Mechanisms ◽  
Broth Microdilution ◽  
Wild Type ◽  
Content Type ◽  
Microdilution Method ◽  
Cutoff Values ◽  
Broth Microdilution Method

ABSTRACTAlthough clinical breakpoints have not been established for mold testing, epidemiological cutoff values (ECVs) are available forAspergillusspp. versus the triazoles and caspofungin. Wild-type (WT) MIC distributions (organisms in a species-drug combination with no acquired resistance mechanisms) were defined in order to establish ECVs for sixAspergillusspp. and amphotericin B. Two sets (CLSI/EUCAST broth microdilution) of available MICs were evaluated: those forA. fumigatus(3,988/833),A. flavus(793/194),A. nidulans(184/69),A. niger(673/140),A. terreus(545/266), andA. versicolor(135/22). Three sets of data were analyzed: (i) CLSI data gathered in eight independent laboratories in Canada, Europe, and the United States; (ii) EUCAST data from a single laboratory; and (iii) the combined CLSI and EUCAST data. ECVs, expressed in μg/ml, that captured 95%, 97.5%, and 99% of the modeled wild-type population (CLSI and combined data) were as follows: forA. fumigatus, 2, 2, and 4; forA. flavus, 2, 4, and 4; forA. nidulans, 4, 4, and 4; forA. niger, 2, 2, and 2; forA. terreus, 4, 4, and 8; and forA. versicolor, 2, 2, and 2. Similar to the case for the triazoles and caspofungin, amphotericin B ECVs may aid in the detection of strains with acquired mechanisms of resistance to this agent.

scholarly journals Multicenter Study of Anidulafungin and Micafungin MIC Distributions and Epidemiological Cutoff Values for Eight Candida Species and the CLSI M27-A3 Broth Microdilution Method

2013 ◽  
Vol 58 (2) ◽  
pp. 916-922 ◽  
Author(s):  
M. A. Pfaller ◽  
A. Espinel-Ingroff ◽  
B. Bustamante ◽  
E. Canton ◽  
D. J. Diekema ◽  
...  
Keyword(s):  
Acquired Resistance ◽  
The United States ◽  
Resistance Mechanisms ◽  
Broth Microdilution ◽  
Wild Type ◽  
Content Type ◽  
Microdilution Method ◽  
Cutoff Values ◽  
Broth Microdilution Method ◽  
Species Specific

ABSTRACTSince epidemiological cutoff values (ECVs) using CLSI MICs from multiple laboratories are not available forCandidaspp. and the echinocandins, we established ECVs for anidulafungin and micafungin on the basis of wild-type (WT) MIC distributions (for organisms in a species-drug combination with no detectable acquired resistance mechanisms) for 8,210Candida albicans, 3,102C. glabrata, 3,976C. parapsilosis, 2,042C. tropicalis, 617C. krusei, 258C. lusitaniae, 234C. guilliermondii, and 131C. dubliniensisisolates. CLSI broth microdilution MIC data gathered from 15 different laboratories in Canada, Europe, Mexico, Peru, and the United States were aggregated to statistically define ECVs. ECVs encompassing 97.5% of the statistically modeled population for anidulafungin and micafungin were, respectively, 0.12 and 0.03 μg/ml forC. albicans, 0.12 and 0.03 μg/ml forC. glabrata, 8 and 4 μg/ml forC. parapsilosis, 0.12 and 0.06 μg/ml forC. tropicalis, 0.25 and 0.25 μg/ml forC. krusei, 1 and 0.5 μg/ml forC. lusitaniae, 8 and 2 μg/ml forC. guilliermondii, and 0.12 and 0.12 μg/ml forC. dubliniensis. Previously reported single and multicenter ECVs defined in the present study were quite similar or within 1 2-fold dilution of each other. For a collection of 230 WT isolates (nofksmutations) and 51 isolates withfksmutations, the species-specific ECVs for anidulafungin and micafungin correctly classified 47 (92.2%) and 51 (100%) of thefksmutants, respectively, as non-WT strains. These ECVs may aid in detecting non-WT isolates with reduced susceptibility to anidulafungin and micafungin due tofksmutations.

scholarly journals Cryptococcus neoformans-Cryptococcus gattii Species Complex: an International Study of Wild-Type Susceptibility Endpoint Distributions and Epidemiological Cutoff Values for Amphotericin B and Flucytosine

2012 ◽  
Vol 56 (6) ◽  
pp. 3107-3113 ◽  
Author(s):  
A. Espinel-Ingroff ◽  
A. Chowdhary ◽  
M. Cuenca-Estrella ◽  
A. Fothergill ◽  
J. Fuller ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Species Complex ◽  
Acquired Resistance ◽  
International Study ◽  
Resistance Mechanisms ◽  
Cryptococcus Gattii ◽  
Wild Type ◽  
Content Type ◽  
Cutoff Values

ABSTRACTClinical breakpoints (CBPs) are not available for theCryptococcus neoformans-Cryptococcus gattiispecies complex. MIC distributions were constructed for the wild type (WT) to establish epidemiologic cutoff values (ECVs) forC. neoformansandC. gattiiversus amphotericin B and flucytosine. A total of 3,590 amphotericin B and 3,045 flucytosine CLSI MICs forC. neoformans(including 1,002 VNI isolates and 8 to 39 VNII, VNIII, and VNIV isolates) and 985 and 853 MICs forC. gattii, respectively (including 42 to 259 VGI, VGII, VGIII, and VGIV isolates), were gathered in 9 to 16 (amphotericin B) and 8 to 13 (flucytosine) laboratories (Europe, United States, Australia, Brazil, Canada, India, and South Africa) and aggregated for the analyses. Additionally, 442 amphotericin B and 313 flucytosine MICs measured by using CLSI-YNB medium instead of CLSI-RPMI medium and 237 Etest amphotericin B MICs forC. neoformanswere evaluated. CLSI-RPMI ECVs for distributions originating in ≥3 laboratories (with the percentages of isolates for which MICs were less than or equal to ECVs given in parentheses) were as follows: for amphotericin B, 0.5 μg/ml forC. neoformansVNI (97.2%) andC. gattiiVGI and VGIIa (99.2 and 97.5%, respectively) and 1 μg/ml forC. neoformans(98.5%) andC. gattiinontyped (100%) and VGII (99.2%) isolates; for flucytosine, 4 μg/ml forC. gattiinontyped (96.4%) and VGI (95.7%) isolates, 8 μg/ml for VNI (96.6%) isolates, and 16 μg/ml forC. neoformansnontyped (98.6%) andC. gattiiVGII (97.1%) isolates. Other molecular types had apparent variations in MIC distributions, but the number of laboratories contributing data was too low to allow us to ascertain that the differences were due to factors other than assay variation. ECVs may aid in the detection of isolates with acquired resistance mechanisms.

scholarly journals Wild-Type MIC Distributions and Epidemiological Cutoff Values for Caspofungin and Aspergillus spp. for the CLSI Broth Microdilution Method (M38-A2 Document)

2011 ◽  
Vol 55 (6) ◽  
pp. 2855-2859 ◽  
Author(s):  
A. Espinel-Ingroff ◽  
A. Fothergill ◽  
J. Fuller ◽  
E. Johnson ◽  
T. Pelaez ◽  
...  
Keyword(s):  
Antifungal Susceptibility ◽  
Acquired Resistance ◽  
The United States ◽  
Resistance Mechanisms ◽  
Broth Microdilution ◽  
Wild Type ◽  
Content Type ◽  
Microdilution Method ◽  
Cutoff Values ◽  
Broth Microdilution Method

ABSTRACTClinical breakpoints have not been established for mold testing. Epidemiologic cutoff values (ECVs) are available for sixAspergillusspp. and the triazoles, but not for caspofungin. Wild-type (WT) minimal effective concentration (MEC) distributions (organisms in a species-drug combination with no acquired resistance mechanisms) were defined in order to establish ECVs for sixAspergillusspp. and caspofungin. The number of available isolates was as follows: 1,691A. fumigatus, 432A. flavus, 192A. nidulans, 440A. niger, 385A. terreus, and 75A. versicolorisolates. CLSI broth microdilution MEC data gathered in five independent laboratories in Canada, Europe, and the United States were aggregated for the analyses. ECVs expressed in μg/ml that captured 95% and 99% of the modeled wild-type population were forA. fumigatus0.5 and 1,A. flavus0.25 and 0.5,A. nidulans0.5 and 0.5,A. niger0.25 and 0.25,A. terreus0.25 and 0.5, andA. versicolor0.25 and 0.5. Although caspofungin ECVs are not designed to predict the outcome of therapy, they may aid in the detection of strains with reduced antifungal susceptibility to this agent and acquired resistance mechanisms.

scholarly journals Multicenter Study of Method-Dependent Epidemiological Cutoff Values for Detection of Resistance in Candida spp. and Aspergillus spp. to Amphotericin B and Echinocandins for the Etest Agar Diffusion Method

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
A. Espinel-Ingroff ◽  
M. Arendrup ◽  
E. Cantón ◽  
S. Cordoba ◽  
E. Dannaoui ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
The United States ◽  
Fungal Isolate ◽  
Diffusion Method ◽  
Wild Type ◽  
Candida Spp ◽  
Content Type ◽  
Phenotypic Resistance ◽  
Cutoff Values

ABSTRACTMethod-dependent Etest epidemiological cutoff values (ECVs) are not available for susceptibility testing of eitherCandidaorAspergillusspecies with amphotericin B or echinocandins. In addition, reference caspofungin MICs forCandidaspp. are unreliable.CandidaandAspergillusspecies wild-type (WT) Etest MIC distributions (microorganisms in a species-drug combination with no detectable phenotypic resistance) were established for 4,341Candida albicans, 113C. dubliniensis, 1,683C. glabrataspecies complex (SC), 709C. krusei, 767C. parapsilosisSC, 796C. tropicalis, 1,637Aspergillus fumigatusSC, 238A. flavusSC, 321A. nigerSC, and 247A. terreusSC isolates. Etest MICs from 15 laboratories (in Argentina, Europe, Mexico, South Africa, and the United States) were pooled to establish Etest ECVs. Anidulafungin, caspofungin, micafungin, and amphotericin B ECVs (in micrograms per milliliter) encompassing ≥97.5% of the statistically modeled population were 0.016, 0.5, 0.03, and 1 forC. albicans; 0.03, 1, 0.03, and 2 forC. glabrataSC; 0.06, 1, 0.25, and 4 forC. krusei; 8, 4, 2, and 2 forC. parapsilosisSC; and 0.03, 1, 0.12, and 2 forC. tropicalis. The amphotericin B ECV was 0.25 μg/ml forC. dubliniensisand 2, 8, 2, and 16 μg/ml for the complexes ofA. fumigatus,A. flavus,A. niger, andA. terreus, respectively. While anidulafungin Etest ECVs classified 92% of theCandida fksmutants evaluated as non-WT, the performance was lower for caspofungin (75%) and micafungin (84%) cutoffs. Finally, although anidulafungin (as an echinocandin surrogate susceptibility marker) and amphotericin B ECVs should identifyCandidaandAspergillusisolates with reduced susceptibility to these agents using the Etest, these ECVs will not categorize a fungal isolate as susceptible or resistant, as breakpoints do.

scholarly journals In VitroActivity of ASP2397 against Aspergillus Isolates with or without Acquired Azole Resistance Mechanisms

2015 ◽  
Vol 60 (1) ◽  
pp. 532-536 ◽  
Author(s):  
Maiken Cavling Arendrup ◽  
Rasmus Hare Jensen ◽  
Manuel Cuenca-Estrella
Keyword(s):  
Amphotericin B ◽  
Target Gene ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Wild Type ◽  
Resistance Mutations ◽  
Content Type

ABSTRACTASP2397 is a new compound with a novel and as-yet-unknown target different from that of licensed antifungal agents. It has activity againstAspergillusandCandida glabrata. We compared itsin vitroactivity against wild-type and azole-resistantA. fumigatusandA. terreusisolates with that of amphotericin B, itraconazole, posaconazole, and voriconazole. Thirty-four isolates, including 4 wild-typeA. fumigatusisolates, 24A. fumigatusisolates with alterations in CYP51A TR/L98H (5 isolates), M220 (9 isolates), G54 (9 isolates), and HapE (1 isolate), andA. terreusisolates (2 wild-type isolates and 1 isolate with an M217I CYP51A alteration), were analyzed. EUCAST E.Def 9.2 and CLSI M38-A2 MIC susceptibility testing was performed. ASP2397 MIC50values (in milligrams per liter, with MIC ranges in parentheses) determined by EUCAST and CLSI were 0.5 (0.25 to 1) and 0.25 (0.06 to 0.25) againstA. fumigatusCYP51A wild-type isolates and were similarly 0.5 (0.125 to >4) and 0.125 (0.06 to >4) against azole-resistantA. fumigatusisolates, respectively. These values were comparable to those for amphotericin B, which were 0.25 (0.125 to 0.5) and 0.25 (0.125 to 0.25) against wild-type isolates and 0.25 (0.125 to 1) and 0.25 (0.125 to 1) against isolates with azole resistance mechanisms, respectively. In contrast, MICs for the azole compounds were elevated and highest for itraconazole: >4 (1 to >4) and 4 (0.5 to >4) against isolates with azole resistance mechanisms compared to 0.125 (0.125 to 0.25) and 0.125 (0.06 to 0.25) against wild-type isolates, respectively. ASP2397 was active againstA. terreusCYP51A wild-type isolates (MIC 0.5 to 1), whereas MICs of both azole and ASP2397 were elevated for the mutant isolate. ASP2397 displayedin vitroactivity againstA. fumigatusandA. terreusisolates which was independent of the presence or absence of azole target gene resistance mutations inA. fumigatus. The findings are promising at a time when azole-resistantA. fumigatusis emerging globally.

scholarly journals Multicenter Study of Isavuconazole MIC Distributions and Epidemiological Cutoff Values for Aspergillus spp. for the CLSI M38-A2 Broth Microdilution Method

2013 ◽  
Vol 57 (8) ◽  
pp. 3823-3828 ◽  
Author(s):  
A. Espinel-Ingroff ◽  
A. Chowdhary ◽  
G. M. Gonzalez ◽  
C. Lass-Flörl ◽  
E. Martin-Mazuelos ◽  
...  
Keyword(s):  
Species Complex ◽  
Acquired Resistance ◽  
Resistance Mechanism ◽  
The United States ◽  
Resistance Mechanisms ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Cutoff Values ◽  
Broth Microdilution Method

ABSTRACTEpidemiological cutoff values (ECVs) were established for the new triazole isavuconazole andAspergillusspecies wild-type (WT) MIC distributions (organisms in a species-drug combination with no detectable acquired resistance mechanisms) that were defined with 855Aspergillus fumigatus, 444A. flavus, 106A. nidulans, 207A. niger, 384A. terreus, and 75A. versicolorspecies complex isolates; 22AspergillussectionUstiisolates were also included. CLSI broth microdilution MIC data gathered in Europe, India, Mexico, and the United States were aggregated to statistically define ECVs. ECVs were 1 μg/ml for theA. fumigatusspecies complex, 1 μg/ml for theA. flavusspecies complex, 0.25 μg/ml for theA. nidulansspecies complex, 4 μg/ml for theA. nigerspecies complex, 1 μg/ml for theA. terreusspecies complex, and 1 μg/ml for theA. versicolorspecies complex; due to the small number of isolates, an ECV was not proposed forAspergillussectionUsti. These ECVs may aid in detecting non-WT isolates with reduced susceptibility to isavuconazole due tocyp51A(anA. fumigatusspecies complex resistance mechanism among the triazoles) or other mutations.

scholarly journals Establishing Genotypic Cutoff Values To Measure Antimicrobial Resistance in Salmonella

2016 ◽  
Vol 61 (3) ◽  
Author(s):  
Gregory H. Tyson ◽  
Shaohua Zhao ◽  
Cong Li ◽  
Sherry Ayers ◽  
Jonathan L. Sabo ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Large Scale ◽  
Acquired Resistance ◽  
Resistance Mechanisms ◽  
Wild Type ◽  
Content Type ◽  
Phenotypic Resistance ◽  
Large Scale Assessment ◽  
Resistance Determinants ◽  
Cutoff Values

ABSTRACT Whole-genome sequencing (WGS) has transformed our understanding of antimicrobial resistance, helping us to better identify and track the genetic mechanisms underlying phenotypic resistance. Previous studies have demonstrated high correlations between phenotypic resistance and the presence of known resistance determinants. However, there has never been a large-scale assessment of how well resistance genotypes correspond to specific MICs. We performed antimicrobial susceptibility testing and WGS of 1,738 nontyphoidal Salmonella strains to correlate over 20,000 MICs with resistance determinants. Using these data, we established what we term genotypic cutoff values (GCVs) for 13 antimicrobials against Salmonella. For the drugs we tested, we define a GCV as the highest MIC of isolates in a population devoid of known acquired resistance mechanisms. This definition of GCV is distinct from epidemiological cutoff values (ECVs or ECOFFs), which currently differentiate wild-type from non-wild-type strains based on MIC distributions alone without regard to genetic information. Due to the large number of isolates involved, we observed distinct MIC distributions for isolates with different resistance gene alleles, including for ciprofloxacin and tetracycline, suggesting the potential to predict MICs based on WGS data alone.

scholarly journals Multicenter Clinical and Molecular Epidemiological Analysis of Bacteremia Due to Carbapenem-Resistant Enterobacteriaceae (CRE) in the CRE Epicenter of the United States

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Michael J. Satlin ◽  
Liang Chen ◽  
Gopi Patel ◽  
Angela Gomez-Simmonds ◽  
Gregory Weston ◽  
...  
Keyword(s):  
New York ◽  
Empirical Therapy ◽  
Carbapenem Resistance ◽  
The United States ◽  
Resistance Mechanisms ◽  
Rapid Diagnostics ◽  
Multicenter Studies ◽  
Content Type ◽  
Medical Centers ◽  
Carbapenem Resistant

ABSTRACT Although the New York/New Jersey (NY/NJ) area is an epicenter for carbapenem-resistant Enterobacteriaceae (CRE), there are few multicenter studies of CRE from this region. We characterized patients with CRE bacteremia in 2013 at eight NY/NJ medical centers and determined the prevalence of carbapenem resistance among Enterobacteriaceae bloodstream isolates and CRE resistance mechanisms, genetic backgrounds, capsular types (cps), and antimicrobial susceptibilities. Of 121 patients with CRE bacteremia, 50% had cancer or had undergone transplantation. The prevalences of carbapenem resistance among Klebsiella pneumoniae, Enterobacter spp., and Escherichia coli bacteremias were 9.7%, 2.2%, and 0.1%, respectively. Ninety percent of CRE were K. pneumoniae and 92% produced K. pneumoniae carbapenemase (KPC-3, 48%; KPC-2, 44%). Two CRE produced NDM-1 and OXA-48 carbapenemases. Sequence type 258 (ST258) predominated among KPC-producing K. pneumoniae (KPC-Kp). The wzi154 allele, corresponding to cps-2, was present in 93% of KPC-3-Kp, whereas KPC-2-Kp had greater cps diversity. Ninety-nine percent of CRE were ceftazidime-avibactam (CAZ-AVI)-susceptible, although 42% of KPC-3-Kp had an CAZ-AVI MIC of ≥4/4 μg/ml. There was a median of 47 h from bacteremia onset until active antimicrobial therapy, 38% of patients had septic shock, and 49% died within 30 days. KPC-3-Kp bacteremia (adjusted odds ratio [aOR], 2.58; P = 0.045), cancer (aOR, 3.61, P = 0.01), and bacteremia onset in the intensive care unit (aOR, 3.79; P = 0.03) were independently associated with mortality. Active empirical therapy and combination therapy were not associated with survival. Despite a decade of experience with CRE, patients with CRE bacteremia have protracted delays in appropriate therapies and high mortality rates, highlighting the need for rapid diagnostics and evaluation of new therapeutics.

scholarly journals Antimicrobial Susceptibility to Azithromycin among Salmonella enterica Isolates from the United States

2011 ◽  
Vol 55 (9) ◽  
pp. 3985-3989 ◽  
Author(s):  
Maria Sjölund-Karlsson ◽  
Kevin Joyce ◽  
Karen Blickenstaff ◽  
Takiyah Ball ◽  
Jovita Haro ◽  
...  
Keyword(s):  
United States ◽  
Antimicrobial Susceptibility ◽  
Salmonella Enterica ◽  
Antimicrobial Agents ◽  
The United States ◽  
Outcome Data ◽  
Content Type ◽  
Susceptibility Data ◽  
Retail Meat ◽  
Clinical Breakpoints

ABSTRACTDue to emerging resistance to traditional antimicrobial agents, such as ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol, azithromycin is increasingly used for the treatment of invasiveSalmonellainfections. In the present study, 696 isolates of non-TyphiSalmonellacollected from humans, food animals, and retail meats in the United States were investigated for antimicrobial susceptibility to azithromycin. Seventy-twoSalmonella entericaserotype Typhi isolates from humans were also tested. For each isolate, MICs of azithromycin and 15 other antimicrobial agents were determined by broth microdilution. Among the non-TyphiSalmonellaisolates, azithromycin MICs among human isolates ranged from 1 to 32 μg/ml, whereas the MICs among the animal and retail meat isolates ranged from 2 to 16 μg/ml and 4 to 16 μg/ml, respectively. AmongSalmonellaserotype Typhi isolates, the azithromycin MICs ranged from 4 to 16 μg/ml. The highest MIC observed in the present study was 32 μg/ml, and it was detected in three human isolates belonging to serotypes Kentucky, Montevideo, and Paratyphi A. Based on our findings, we propose an epidemiological cutoff value (ECOFF) for wild-typeSalmonellaof ≤16 μg/ml of azithromycin. The susceptibility data provided could be used in combination with clinical outcome data to determine tentative clinical breakpoints for azithromycin andSalmonella enterica.

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