Dataset Information

In vitro activity of ceftazidime/avibactam and comparators against Gram-negative bacterial isolates collected from Latin American centres between 2015 and 2017.

ABSTRACT:

Objectives

We report the in vitro activity of ceftazidime/avibactam and comparators against 7729 Enterobacterales isolates and 2053 Pseudomonas aeruginosa isolates collected from six Latin American countries between 2015 and 2017.

Methods

A central reference laboratory performed antimicrobial susceptibility testing using broth microdilution panels according to CLSI guidelines. The presence of β-lactamases was confirmed using multiplex PCR assays.

Results

Susceptibility rates among Enterobacterales were highest for ceftazidime/avibactam (99.3%, MIC90 = 0.5 mg/L), meropenem (95.4%, MIC90 = 0.12 mg/L) and amikacin (93.5%, MIC90 = 8 mg/L). High susceptibility rates were observed for ceftazidime/avibactam in all six countries. The majority of carbapenemase-positive isolates among Enterobacterales (N = 366, 4.7%) were susceptible to ceftazidime/avibactam (86.9%), colistin (76.8%) and amikacin (60.9%); MBL-positive isolates (N = 49, 0.6%) were susceptible only to colistin (79.6%), with a minority susceptible to amikacin (49.0%), aztreonam and levofloxacin (both 30.6%). Highest rates of susceptibility among P. aeruginosa isolates were for colistin (99.2%) and ceftazidime/avibactam (86.6%), with rates of susceptibility to all other agents being <80.0%. MDR P. aeruginosa isolates (N = 712, 34.7%) had a high rate of susceptibility to colistin (98.9%); the rate of susceptibility to ceftazidime/avibactam was 61.4% and <50.0% to all other comparator agents. A total of 235 (11.4%) isolates of P. aeruginosa were carbapenemase positive and 148 (7.2%) were MBL positive; both subsets had high rates of susceptibility to colistin (98.3% and 100%, respectively).

Conclusions

Ceftazidime/avibactam susceptibility rates in Latin American countries are stable and high; ceftazidime/avibactam can be an appropriate treatment for patients with infections caused by Enterobacterales or P. aeruginosa and for whom treatment options may be limited.

SUBMITTER: Stone GG

PROVIDER: S-EPMC7303818 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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In vitro activity of ceftazidime/avibactam and comparators against Gram-negative bacterial isolates collected from Latin American centres between 2015 and 2017.

Stone Gregory G GG Ponce-de-Leon Alfredo A

The Journal of antimicrobial chemotherapy 20200701 7

<h4>Objectives</h4>We report the in vitro activity of ceftazidime/avibactam and comparators against 7729 Enterobacterales isolates and 2053 Pseudomonas aeruginosa isolates collected from six Latin American countries between 2015 and 2017.<h4>Methods</h4>A central reference laboratory performed antimicrobial susceptibility testing using broth microdilution panels according to CLSI guidelines. The presence of β-lactamases was confirmed using multiplex PCR assays.<h4>Results</h4>Susceptibility rate ...[more]

PMID: 32277820

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Project description:The International Network for Optimal Resistance Monitoring (INFORM) global surveillance program collected clinical isolates of Enterobacteriaceae (n = 7,665) and Pseudomonas aeruginosa (n = 1,794) from 26 medical centers in six Latin American countries from 2012 to 2015. The in vitro activity of ceftazidime-avibactam and comparators was determined for the isolates using the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution method. Enterobacteriaceae were highly susceptible (99.7%) to ceftazidime-avibactam, including 99.9% of metallo-β-lactamase (MBL)-negative isolates; 87.4% of all P. aeruginosa isolates and 92.8% of MBL-negative isolates were susceptible to ceftazidime-avibactam. Susceptibility to ceftazidime-avibactam ranged from 99.4% to 100% for Enterobacteriaceae and from 79.1% to 94.7% for P. aeruginosa when isolates were analyzed by country of origin. Ceftazidime-avibactam inhibited 99.6% to 100% of Enterobacteriaceae isolates that carried serine β-lactamases, including extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases (KPC and OXA-48-like) as well as 99.7%, 99.6%, 99.5%, and 99.2% of MBL-negative isolates demonstrating ceftazidime-nonsusceptible, multidrug-resistant (MDR), meropenem-nonsusceptible, and colistin-resistant phenotypes, respectively. Among carbapenem-nonsusceptible isolates of P. aeruginosa (n = 750), 14.7% carried MBLs with or without additional acquired serine β-lactamases, while in the majority of isolates (70.0%), no acquired β-lactamase was identified. Ceftazidime-avibactam inhibited 89.5% of carbapenem-nonsusceptible P. aeruginosa isolates in which no acquired β-lactamase was detected. Overall, clinical isolates of Enterobacteriaceae collected in Latin America from 2012 to 2015 were highly susceptible to ceftazidime-avibactam, including isolates that exhibited resistance to ceftazidime, meropenem, colistin, or an MDR phenotype. Country-specific variations were noted in the susceptibility of P. aeruginosa isolates to ceftazidime-avibactam.

Project description:BackgroundIncreases in resistance to fluoroquinolones have been correlated with the use of levofloxacin in the treatment of infections caused by Escherichia coli. The analysis presents the in vitro activity of ceftazidime-avibactam and comparator agents against 10,840 levofloxacin-resistant E. coli isolates collected from four geographic regions (Africa/Middle East, Europe, Asia/South Pacific, Latin America) between 2012 and 2018.MethodsNon-duplicate clinical isolates of E. coli were collected from participating centres and shipped to IHMA, Inc., (Schaumburg, IL, USA). Susceptibility testing was performed with frozen broth microdilution panels manufactured by IHMA, according to CLSI guidelines. Levofloxacin-resistance was defined at a minimum inhibitory concentration of ≥ 2 mg/L. Isolates collected between 2012 and 2015 were tested for extended-spectrum β-lactamase (ESBL) activity by determining susceptibility to cefotaxime, cefotaxime-clavulanate, ceftazidime, and ceftazidime-clavulanate as recommended by CLSI guidelines. Isolates collected between 2016 and 2018 were identified as ESBL-positive by genotype using multiplex polymerase chain reaction assays.ResultsA total of 74.8% of levofloxacin-resistant E. coli isolates in the analysis were from three culture sources: urinary tract infections (N = 3229; 29.8%), skin and skin structure infections (N = 2564; 23.7%) and intra-abdominal infections (N = 2313; 21.3%). Susceptibility rates to ceftazidime-avibactam were consistently high in all regions against both ESBL-positive (97.0% in Asia/South Pacific to 99.7% in Africa/Middle East and Latin America) and ESBL-negative isolates (99.4% in Asia/South Pacific to 100% in Latin America). Susceptibility was also high in each region among ESBL-positive and ESBL-negative isolates to colistin (≥ 98.5%), imipenem (≥ 96.5%), meropenem (≥ 96.5%) and tigecycline (≥ 94.1%).ConclusionsAntimicrobial susceptibility to ceftazidime-avibactam among levofloxacin-resistant E. coli isolates, including ESBL-positive isolates, collected from four geographical regions between 2012 and 2018 was consistently high. Susceptibility to the comparator agents colistin, tigecycline, imipenem and meropenem was also high.

Project description:Oxacillinases (OXA)-48-like β-lactamases are one of the most common resistance determinants among carbapenem-resistant Enterobacterales reported globally. Moreover, there is no standard treatment available against organisms producing OXA-48-like enzymes, and they are sometimes difficult to detect, making treatment challenging. The objective of this study was to evaluate the distribution and antimicrobial susceptibility of blaOXA-48-like Enterobacterales isolates against ceftazidime-avibactam (CAZ-AVI) and a panel of comparators collected worldwide from 2016 to 2020 as a part of the Antimicrobial Testing Leadership and Surveillance program. Among all the Enterobacterales isolates collected, 1.8% (1,690/94,052) carried blaOXA-48-like, and a majority of those were identified as K. pneumoniae (86.5%, 1,462/1,690). Among all the blaOXA-48-like isolates, 88.9% (1,502/1,690) were extended-spectrum β-lactamase (ESBL)-positive, 20.7% (350/1,690) were metallo-β-lactamase (MBL)-positive, and 8.9% (150/1,690) were ESBL- and MBL-negative. There were 10 different variants of the OXA-48-like family of enzymes detected, with the major variant being blaOXA-48 (50.2%, 848/1,690), blaOXA-232 (29.3%, 496/1,690), and blaOXA-181 (18.0%, 304/1,690). Overall, all the blaOXA-48-like isolates showed a susceptibility of 78.6% to CAZ-AVI. Importantly, high susceptibility to CAZ-AVI was shown by all the blaOXA-48 type, MBL-negative isolates (n = 1,380, ≥99.0%), and all the MBL-negative isolates (n = 1,300, ≥97.6%) of the major variants (blaOXA-48, blaOXA-232, and blaOXA-181) studied. Among the comparator agents, all isolates showed good susceptibility to only tigecycline (>95.0%) and colistin (>78.6%). Considering the limited treatment options available, CAZ-AVI could be considered as a potential treatment option against blaOXA-48-like Enterobacterales. However, routine surveillance and appropriate stewardship strategies for these organisms may help identify emerging resistance mechanisms and effective treatment of infections.ImportanceResistance to carbapenems among Enterobacterales is often due to the production of enzymes that are members of the oxacillinases (OXA)-48-like family. These organisms can also be resistant to other classes of drugs and are difficult to identify and treat. This study evaluated the activity of the drug ceftazidime-avibactam (CAZ-AVI) and other comparator agents against a global collection of Enterobacterales that produce OXA-48-like enzymes. CAZ-AVI was active against blaOXA-48-like Enterobacterales, and only colistin and tigecycline were similarly active among the comparator agents, highlighting the limited treatment options against these organisms. Continued surveillance of the distribution of these OXA 48-like producing Enterobacterales and monitoring of resistance patterns along with the implementation of antimicrobial stewardship measures to guide antibiotic use and appropriate treatment are necessary to avoid drug resistance among these organisms.

Project description:The activities of the novel β-lactam-β-lactamase inhibitor combination ceftazidime-avibactam and comparator agents were evaluated against a contemporary collection of clinically significant Gram-negative bacilli. Avibactam is a novel non-β-lactam β-lactamase inhibitor that inhibits Ambler class A, C, and some D enzymes. A total of 10,928 Gram-negative bacilli-8,640 Enterobacteriaceae, 1,967 Pseudomonas aeruginosa, and 321 Acinetobacter sp. isolates-were collected from 73 U.S. hospitals and tested for susceptibility by reference broth microdilution methods in a central monitoring laboratory (JMI Laboratories, North Liberty, IA, USA). Ceftazidime was combined with avibactam at a fixed concentration of 4 μg/ml. Overall, 99.8% of Enterobacteriaceae strains were inhibited at a ceftazidime-avibactam MIC of ≤4 μg/ml. Ceftazidime-avibactam was active against extended-spectrum β-lactamase (ESBL)-phenotype Escherichia coli and Klebsiella pneumoniae, meropenem-nonsusceptible (MIC≥2 μg/ml) K. pneumoniae, and ceftazidime-nonsusceptible Enterobacter cloacae. Among ESBL-phenotype K. pneumoniae strains, 61.1% were meropenem susceptible and 99.3% were inhibited at a ceftazidime-avibactam MIC of ≤4 μg/ml. Among P. aeruginosa strains, 96.9% were inhibited at a ceftazidime-avibactam MIC of ≤8 μg/ml, and susceptibility rates for meropenem, ceftazidime, and piperacillin-tazobactam were 82.0, 83.2, and 78.3%, respectively. Ceftazidime-avibactam was the most active compound tested against meropenem-nonsusceptible P. aeruginosa (MIC50/MIC90, 4/16 μg/ml; 87.3% inhibited at ≤8 μg/ml). Acinetobacter spp. (ceftazidime-avibactam MIC50/MIC90, 16/>32 μg/ml) showed high rates of resistance to most tested agents. In summary, ceftazidime-avibactam demonstrated potent activity against a large collection of contemporary Gram-negative bacilli isolated from patients in U.S. hospitals in 2012, including organisms that are resistant to most currently available agents, such as K. pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae and meropenem-nonsusceptible P. aeruginosa.

Project description:Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae isolates have been increasingly reported worldwide, and therapeutic options to treat infections caused by these organisms are limited. We evaluated the activity of ceftazidime-avibactam and comparators against 456 Enterobacteriaceae isolates carrying blaKPC collected from 79 U.S. hospitals during 2012 to 2015. Overall, ceftazidime-avibactam (MIC50/90, 0.5/2 μg/ml; 99.3% susceptible) and tigecycline (MIC50/90, 0.5/1 μg/ml; 98.9% susceptible at ≤2 μg/ml) were the most active agents. Only 80.5% and 59.0% of isolates were susceptible to colistin and amikacin, respectively. All three isolates (0.7%) displaying resistance to ceftazidime-avibactam (K. pneumoniae; MICs, ≥16 μg/ml) were evaluated using whole-genome sequencing analysis and relative quantification of expression levels of porins and efflux pump. Two isolates carried metallo-β-lactamase genes, blaNDM-1 or blaVIM-4, among other β-lactam resistance mechanisms, and one displayed a premature stop codon in ompK35 and decreased expression of ompK36 Ceftazidime-avibactam was active against 100.0 and 99.3% of isolates carrying blaKPC-3 (n = 221) and blaKPC-2 (n = 145), respectively. Isolates carrying blaKPC were more commonly recovered from pneumonia (n = 155), urinary tract (n = 93), and skin/soft tissue (n = 74) infections. Ceftazidime-avibactam (97.8 to 100.0% susceptible) was consistently active against isolates from all infection sites. K. pneumoniae (83.3% of the collection) susceptibility rates were 99.2% for ceftazidime-avibactam, 98.9% for tigecycline, and 80.1% for colistin. Ceftazidime-avibactam susceptibility did not vary substantially when comparing isolates from intensive care unit (ICU) patients to those from non-ICU patients. Ceftazidime-avibactam was active against this large collection of isolates carrying blaKPC and represents a valuable addition to the armamentarium currently available for the treatment of infections caused by KPC-producing Enterobacteriaceae.

Project description:The Antimicrobial Testing Leadership and Surveillance (ATLAS) global surveillance program collected clinical isolates of Enterobacterales (n = 8416) and Pseudomonas aeruginosa (n = 2521) from 41 medical centers in 10 Latin American countries from 2017 to 2019. In vitro activities of ceftazidime-avibactam and comparators were determined using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Overall, 98.1% of Enterobacterales and 86.9% of P. aeruginosa isolates were susceptible to ceftazidime-avibactam. When isolates were analyzed by country of origin, susceptibility to ceftazidime-avibactam for Enterobacterales ranged from 97.8% to 100% for nine of 10 countries (except Guatemala, 86.3% susceptible) and from 75.9% to 98.4% for P. aeruginosa in all 10 countries. For Enterobacterales, 100% of AmpC-positive, ESBL- and AmpC-positive, GES-type carbapenemase-positive, and OXA-48-like-positive isolates were ceftazidime-avibactam-susceptible as were 99.8%, 91.8%, and 74.7% of ESBL-positive, multidrug-resistant (MDR), and meropenem-nonsusceptible isolates. Among meropenem-nonsusceptible isolates of Enterobacterales, 24.4% (139/570) carried a metallo-β-lactamase (MBL); 83.3% of the remaining meropenem-nonsusceptible isolates carried another class of carbapenemase and 99.4% of those isolates were ceftazidime-avibactam-susceptible. Among meropenem-non-susceptible isolates of P. aeruginosa (n = 835), 25.6% carried MBLs; no acquired β-lactamase was identified in the majority of isolates (64.8%; 87.2% of those isolates were ceftazidime-avibactam-susceptible). Overall, clinical isolates of Enterobacterales collected in Latin America from 2017 to 2019 were highly susceptible to ceftazidime-avibactam, including isolates carrying ESBLs, AmpCs, and KPCs. Country-specific variation in susceptibility to ceftazidime-avibactam was more common among isolates of P. aeruginosa than Enterobacterales. The frequency of MBL-producers among Enterobacterales from Latin America was low (1.7% of all isolates; 146/8,416), but higher than reported in previous surveillance studies.

Project description:BackgroundData on antibiotic resistance is essential to adapt treatment strategies against the rapidly changing reality of antimicrobial resistance.ObjectiveTo study the in vitro activity of ceftaroline, ceftazidime-avibactam, and comparators against Gram-positive and Gram-negative bacteria collected from China in the year 2018.MethodsA total of 2301 clinical isolates were collected from 17 medical center laboratories in China, which participated in the ATLAS program in 2018. Antimicrobial susceptibilities were determined by the broth microdilution method at a central laboratory. Clinical and Laboratory Standards Institute (CLSI) breakpoints were used to interpret the results except for tigecycline, for which the US Food and Drug Administration (FDA) breakpoint were used.ResultsThe susceptibility rates of methicillin-resistant Staphylococcus aureus (MRSA), penicillin-resistant Streptococcus pneumoniae (PRSP), and β-hemolytic streptococcus to ceftaroline were 83.9%, 100%, and 100%, respectively. Escherichia coli, imipenem-susceptible (IMP-S) Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, IMP-S Enterobacter cloacae, Proteus mirabilis, Morganella morganii, Serratia marcescens and Pseudomonas aeruginosa had high susceptibility rates to ceftazidime-avibactam (95.8%, 100%, 97.7%, 94.5%, 100%, 90.2%, 96.0%, 97.5% and 90.7%, respectively). However, imipenem-resistant Escherichia coli and imipenem-resistant Pseudomonas aeruginosa demonstrated low susceptibility to ceftazidime-avibactam (33.3% and 75.8%, respectively). Against MRSA, methicillin-susceptible Staphylococcus aureus (MSSA), S. pneumoniae and β-hemolytic streptococci, the susceptibility rates of tigecycline were 93.5%, 99.2%, 100% and 100%, respectively. Levofloxacin also showed high in vitro activity against S. pneumoniae and β-hemolytic streptococci with a susceptibility rate of 100% and 98.4%. The susceptibility rate of E. faecalis to ampicillin was 100%. Among Gram-negative isolates, tigecycline and colistin showed good activity against E. coli, K. pneumoniae, imipenem-resistant E. cloacae, C. freundii and A. baumannii (susceptibility rates and intermediate susceptibility rates of 99.3% and 96.8%, 95.4% and 94.5%, 100% and 87.5%, 96.4% and 89.3%, MIC90 of 2 mg/L and 97.4%, respectively). E. coli and E. cloacae had high susceptibility rates to imipenem and meropenem (93.0% and 92.8%, 89.8% and 92.1%, respectively). M. morganii and P. mirabilis demonstrated meropenem and piperacillin-tazobactam susceptibility rates of 96.0% and 94.0%, 94.1% and 92.2%, respectively.ConclusionCeftaroline showed good activity among tested antimicrobial agents against Gram-positive species, while ceftazidime-avibactam had good activity against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Proteus mirabilis, Morganella morganii, Serratia marcescens and Pseudomonas aeruginosa excluding carbapenem-resistant isolates.

Project description:Objective: To systematically review and compare the efficacy and posttreatment resistance of ceftazidime-avibactam therapy and ceftazidime-avibactam-based combination therapy in patients with Gram-negative pathogens. Methods: PubMed, Embase, Web of Science, CNKI, and Wanfang Data databases were searched from their inception up to March 31, 2021, to obtain studies on ceftazidime-avibactam therapy versus ceftazidime-avibactam-based combination therapy in patients with carbapenem-resistant Gram-negative pathogens. The primary outcome was mortality rate, and the second outcomes were microbiologically negative, clinical success, and the development of resistance after ceftazidime-avibactam treatment. Results: Seventeen studies representing 1,435 patients (837 received ceftazidime-avibactam-based combination therapy and 598 received ceftazidime-avibactam therapy) were included in the meta-analysis. The results of the meta-analysis showed that no statistically significant difference was found on mortality rate (Petos odds ratio (OR) = 1.03, 95% confidence interval (CI) 0.79-1.34), microbiologically negative (OR = 0.99, 95% CI 0.54-1.81), and clinical success (OR =0.95, 95% CI 0.64-1.39) between ceftazidime-avibactam-based combination therapy and ceftazidime-avibactam therapy. Although there was no difference in posttreatment resistance of ceftazidime-avibactam (OR = 0.65, 95% CI 0.34-1.26) in all included studies, a trend favoring the combination therapy was found (according to the pooled three studies, OR = 0.18, 95% CI 0.04-0.78). Conclusions: The current evidence suggests that ceftazidime-avibactam-based combination therapy may not have beneficial effects on mortality, microbiologically negative, and clinical success to patients with carbapenem-resistant Gram-negative pathogens. A trend of posttreatment resistance occurred more likely in ceftazidime-avibactam therapy than the combination therapy. Due to the limited number of studies that can be included, additional high-quality studies are needed to verify the above conclusions.

Project description:BackgroundThis antimicrobial surveillance study reports in vitro antimicrobial activity and susceptibility data for a panel of agents against respiratory isolates of Enterobacterales and Pseudomonas aeruginosa.MethodsIsolates from respiratory specimens were collected in Africa/Middle East, Asia/South Pacific, Europe and Latin America between 2016 and 2018, as part of the Antimicrobial Testing Leadership and Surveillance (ATLAS) program. Broth microdilution methodology was used to quantify minimum inhibitory concentrations, from which rates of susceptibility were determined using EUCAST breakpoints (version 10). Rates of subsets with genes encoding β-lactamases (extended-spectrum β-lactamases [ESBLs], serine carbapenemases and metallo-β-lactamases [MBLs]) were also determined, as well as rates of multidrug-resistant (MDR) P. aeruginosa.ResultsAmong all respiratory Enterobacterales isolates, susceptibility to ceftazidime-avibactam, meropenem, colistin and amikacin was ≥94.4% in each region. For Enterobacterales isolates that were ESBL-positive or carbapenemase-positive/MBL-negative, ceftazidime-avibactam susceptibility was 93.6 and 98.9%, respectively. Fewer than 42.7% of MBL-positive Enterobacterales isolates were susceptible to any agents, except colistin (89.0% susceptible). Tigecycline susceptibility was ≥90.0% among Citrobacter koseri and Escherichia coli isolates, including all β-lactamase-positive subsets. ESBL-positive Enterobacterales were more commonly identified in each region than isolates that were ESBL/carbapenemase-positive; carbapenemase-positive/MBL-negative; or MBL-positive. Among all respiratory P. aeruginosa isolates, the combined susceptibility rates (susceptible at standard dosing regimen plus susceptible at increased exposure) were highest to ceftazidime-avibactam, colistin and amikacin (≥82.4% in each region). Susceptibility to colistin was ≥98.1% for all β-lactamase-positive subsets of P. aeruginosa. The lowest rates of antimicrobial susceptibility were observed among MBL-positive isolates of P. aeruginosa (≤56.6%), with the exception of colistin (100% susceptible). MDR P. aeruginosa were most frequently identified in each region (18.7-28.7%), compared with the subsets of ESBL-positive; carbapenemase-positive/MBL-negative; or MBL-positive isolates.ConclusionsRates of susceptibility among the collections of respiratory Enterobacterales and P. aeruginosa isolates were highest to ceftazidime-avibactam, colistin and amikacin in each region. Tigecycline was active against all subsets of C. koseri and E. coli, and colistin was active against all subsets of P. aeruginosa. The findings of this study indicate the need for continued antimicrobial surveillance among respiratory Gram-negative pathogens, in particular those with genes encoding MBLs.

Project description:Ceftazidime-avibactam (CZA) is the combination of a third-generation cephalosporin and a new non-β-lactam β-lactamase inhibitor capable of inactivating class A, C, and some D β-lactamases. From a collection of 2,727 clinical isolates of Enterobacterales (n = 2,235) and P. aeruginosa (n = 492) that were collected between 2016 and 2017 from five Latin American countries, we investigated the molecular resistance mechanisms to CZA of 127 (18/2,235 [0.8%] Enterobacterales and 109/492 [22.1%] P. aeruginosa). First, by qPCR for the presence of genes encoding KPC, NDM, VIM, IMP, OXA-48-like, and SPM-1 carbapenemases, and second, by whole-genome sequencing (WGS). From the CZA-resistant isolates, MBL-encoding genes were detected in all 18 Enterobacterales and 42/109 P. aeruginosa isolates, explaining their resistant phenotype. Resistant isolates that yielded a negative qPCR result for any of the MBL encoding genes were subjected to WGS. The WGS analysis of the 67 remaining P. aeruginosa isolates showed mutations in genes previously associated with reduced susceptibility to CZA, such as those involved in the MexAB-OprM efflux pump and AmpC (PDC) hyperproduction, PoxB (blaOXA-50-like), FtsI (PBP3), DacB (PBP4), and OprD. The results presented here offer a snapshot of the molecular epidemiological landscape for CZA resistance before the introduction of this antibiotic into the Latin American market. Therefore, these results serve as a valuable comparison tool to trace the evolution of the resistance to CZA in this carbapenemase-endemic geographical region. IMPORTANCE In this manuscript, we determine the molecular mechanisms of ceftazidime-avibactam resistance in Enterobacterales and P. aeruginosa isolates from five Latin American countries. Our results reveal a low rate of resistance to ceftazidime-avibactam among Enterobacterales; in contrast, resistance in P. aeruginosa has proven to be more complex, as it might involve multiple known and possibly unknown resistance mechanisms.

Dataset Information

In vitro activity of ceftazidime/avibactam and comparators against Gram-negative bacterial isolates collected from Latin American centres between 2015 and 2017.

Objectives

Methods

Results

Conclusions

Publications

In vitro activity of ceftazidime/avibactam and comparators against Gram-negative bacterial isolates collected from Latin American centres between 2015 and 2017.

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