ESBL Phenotype Research Articles

AmpC- and Extended-Spectrum β-Lactamase–Producing Enterobacteriaceae Detected in Fresh Produce in Central Ohio

Salad vegetables purchased from farmer's markets and grocery stores in central Ohio during the summers of 2015 and 2016 were tested for the presence of Enterobacteriaceae resistant to extended-spectrum cephalosporins and carbapenems, Salmonella contamination, and coliform bacterial counts. A total of 364 samples were collected from 36 farmers' markets and 33 grocery stores. Using selective media, we found 23 (6.3%) samples that produced Enterobacteriaceae expressing an AmpC β-lactamase phenotype, with 11 (3.0%) confirmed to contain blaCMY and 6 (1.6%) that produced Enterobacteriaceae with an extended-spectrum β-lactamase (ESBL) phenotype, 1 (0.3%) of which was confirmed to contain blaCTX-M. All blaCMY and blaCTX-M strains were isolated from leafy greens. No Salmonella spp. or carbapenem-resistant Enterobacteriaceae were recovered from fresh produce samples. Adjusting for year, the geometric mean coliform count differed (P < 0.05) between produce types, with the count in tomatoes (15 CFU/mL) being lower than those in cucumbers (77.4 CFU/mL) and leafy greens (75.0 CFU/mL). The coliform counts also differed (P < 0.05) between years, with 19.6 CFU/mL in 2015 and 96.0 CFU/mL in 2016. There was no difference in coliform counts or the prevalences of Enterobacteriaceae expressing AmpC or ESBL phenotypes in produce purchased from farmers' markets and grocery stores.

Antimicrobial drug resistance of Escherichia coli strains isolated from urinary tract infection and raw beef meat in Oum El Bouaghi city of Algeria

Antimicrobial resistance, especially in Escherichia coli, represents one of the most important human and animal health-threatening issues worldwide. The aim of this study was the characterization and the comparison of Antimicro-bial drug resistance of Escherichia coli strains isolated from urinary tract in-fection (UTI) and food (raw beef meat) in Oum El Bouaghi city-Algeria. The determination of antibiotics susceptibility pattern was realized by using the agar disk diffusion method, according to the recommendations of the French Society for Microbiology (FSM, 2019). A total, 159 E. coli were obtained from both clinical and food samples, with a frequency of isolation of 100% from raw beef meat and 59% from UTI. ESBL phenotype was detected only in 17% of clinical isolates. Also, the results of this work reveal that there is a highly significant difference in antibiotic resistance between clinical and foodborne isolates except for gentamicin. This high prevalence is a warning sign to adopt new control policies to prevent the further spread of this antimicrobial resistance.

Coexistence of aminoglycoside resistance genes in CTX-M-producing isolates of Klebsiella pneumoniae in Bushehr province, Iran.

Background and Objectives:Increasing the rate of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae has given rise to a major healthcare issue in clinical settings over the past few years. Treatment of these strains is hardly effective since the plasmid encoding ESBL may also carry other resistance genes including aminoglycosides. The current study aimed to evaluate the prevalence of ESBL-producing K. pneumoniae and investigate the coexistence of Cefoxitamase-Munich (blaCTX-M) with aminoglycoside-modifying enzyme (AME) genes, aac(3)IIa as well as aac(6′)Ib, in CTX-M-producing K. pneumoniae isolated from patients in Bushehr province, Iran.Materials and Methods:A total of 212 K. pneumoniae isolates were collected and confirmed using polymerase chain reaction (PCR) of the malate dehydrogenase gene. Isolates were screened for production of ESBL. Phenotypic confirmatory test was performed using combined disk test. The genes encoding CTX-M groups and AME genes, aac(3)IIa and aac(6′)Ib, were investigated by PCR.Results:The ESBL phenotype was detected in 56 (26.4%) K. pneumoniae isolates. Moreover, 83.9% of ESBL-producing isolates carried the genes for CTX-M type β-lactamases, which were distributed into the two genetic groups of CTX-M-1 (97.8%)- and CTX-M-2 (2.1%)-related enzymes. Notably, among K. pneumoniae isolates containing the blaCTX-M gene, 68.08% of isolates harbored AME genes. In addition, the coexistence of blaCTX-M with aac(3)-IIa and aac(6′)-Ib was observed in 46.8% of CTX-M-producing K. pneumoniae isolates.Conclusion:This study provides evidence of a high prevalence of AME genes in CTX-M-producing K. pneumoniae isolates; therefore, in the initial empirical treatment of infections caused by ESBL-KP in regions with such antibiotic resistance patterns, aminoglycoside combination therapy should be undertaken carefully.

Occurrence of antibiotic resistance among Enterobacterales isolated from raw and ready-to-eat food – phenotypic and genotypic characteristics

ABSTRACT The aim of this study was phenotypic and genotypic characterization of antibiotic-resistant food-borne Enterobacterales. The largest number of isolates was identified as Enterobacter cloacae (42.4%) followed by Escherichia coli (9.8%), Proteus mirabilis, Salmonella enterica, Proteus penneri, Citrobacter freundii (7.6% each), Citrobacter braakii (6.6%), Klebsiella pneumoniae and Klebsiella oxytoca (5.4% each). More than half of isolates (52.2%) were resistant to at least one antibiotic. The majority were resistant to amoxicillin-clavulanate (28.3%) and ampicillin (19.5%). ESBL(+) phenotype was showed by 26 isolates and AmpC(+) phenotype by 32 isolates. The bla CTX-M gene was carried by 53.8% of ESBL-positive isolates, gene from CIT family by 43.8% of AmpC-positive isolates. Our results suggest that more attention should be paid to antibiotic resistance of food-borne Enterobacterales. The presence of transmissible antibiotic resistance markers is an important criterion in the evaluation of food safety.

#9: Frequency and Antimicrobial Susceptibility of Gram-Negative Organisms Causing Bloodstream Infections in Pediatric Patients from United States (US) Medical Centers (2014–2018)

Abstract Background Ceftazidime–avibactam is US FDA approved for the treatment of pneumonia and complicated intra-abdominal and urinary tract infections in adults, and it is in late-stage clinical development for the treatment of pediatric patients. Methods Organisms were consecutively collected from pediatric patients (≤17 years old) with bloodstream infections in 33 US medical centers in 2014–2018. Enterobacterales, P. aeruginosa, and H. influenzae isolates (n = 976) were susceptibility (S) tested against ceftazidime–avibactam and comparators by reference broth microdilution methods; 42.9% of isolates tested were from patients &amp;lt;1 year old, and 70.7% from patients ≤5 years old. Isolates with an ESBL–phenotype were screened for β-lactamase genes. Results Overall, 40.1% of organisms were Gram-negative bacteria (GNB), 57.0% Gram-positives, and 2.8% Candida spp. The five most common GNB were E. coli (32.4% of GNB), K. pneumoniae (17.3%), E. cloacae (9.8%), P. aeruginosa (9.2%), and S. marcescens (5.5%; Table). Enterobacterales, P. aeruginosa, and H. influenzae isolates combined represented 89% of GNB and all isolates (100.0%) were susceptible to ceftazidime–avibactam. Among Enterobacterales (n = 845; MIC50/90, 0.12/0.25 mg/L), the highest ceftazidime–avibactam MIC value was only 4 mg/L and 99.2% of isolates were inhibited at ≤1 mg/L. Enterobacterales susceptibility to ceftriaxone, piperacillin–tazobactam, ceftolozane–tazobactam, and meropenem were 88.2%, 93.1%, 97.5%, and 99.5%, respectively. Forty-four Enterobacterales isolates (5.2%) produced an ESBL, including CTX-M-type (n = 35 [79.5% of ESBL producers], 21 being CTX-M-15), SHV-type (12; 27.3%), and OXA-1/30 (9; 20.5%). Twelve isolates (27.3%) produced &amp;gt;1 ESBL. No carbapenemase gene was detected. Among ESBL producers, highest ceftazidime–avibactam MIC was 2 mg/L, and susceptibility rates for ceftolozane–tazobactam and meropenem were 92.9% and 100.0%, respectively. Ceftazidime–avibactam exhibited complete activity against P. aeruginosa (MIC50/90, 2/4 mg/L; 100.0% susceptible). P. aeruginosa susceptibility rates for meropenem, piperacillin–tazobactam, and ceftolozane–tazobactam were 82.5%, 85.6%, and 100.0%, respectively; and 10.3% of isolates exhibited multidrug-resistance phenotype (not susceptible to ≥3 classes). Ceftazidime–avibactam was highly active against H. influenzae (n = 34; MIC50/90, ≤0.015/0.03 mg/L; highest MIC, 0.06 m/L). Conclusions Ceftazidime–avibactam exhibited potent activity against a large collection of GNB isolated from pediatric patients with bacteremia and showed complete coverage (100.0% susceptibility) against P. aeruginosa, Enterobacterales, and H. influenzae.

ESBL-producing strains isolated from imported cases of enteric fever in England and Wales reveal multiple chromosomal integrations of blaCTX-M-15 in XDR Salmonella Typhi.

There are approximately 300 cases of enteric fever reported annually from England and Wales; most are imported infections. Clinical management of enteric fever remains a challenge with the emergence of ESBL-producing strains, especially XDR Salmonella Typhi from Sindh, Pakistan. All strains of S. Typhi and Salmonella Paratyphi A isolated from cases presenting with symptoms of enteric fever in England and Wales, between 1 April 2014 and 31 March 2020, were characterized using WGS. Antibiotic susceptibility testing was performed using an agar dilution method. ESBL strains contributed to 69 cases of enteric fever (S. Typhi n = 68, S. Paratyphi A n = 1); 68 were imported (Pakistan n = 64, Iraq n = 2, Bangladesh n = 1 and India n = 1). Ages ranged from 1 to 56 years, 36/69 (52%) were children, 52% were female and the duration of hospital stay ranged from 1 to 23 days. The ESBL phenotype was conferred by the presence of blaCTX-M-15 (S. Typhi n = 67 and S. Paratyphi A n = 1) or blaCTX-M-55 (S. Typhi n = 1). An IncY plasmid harbouring blaCTX-M-15 and qnr was detected in 56 strains from Pakistan. The IncY plasmid was absent in the remaining strains and there was evidence of a 4 kb ISEcpl-blaCTX-M-15-tnp gene cassette insertion into the chromosome at one of three integration points. Chromosomal integration of blaCTX-M-15 within the XDR Sindh strains may lead to the maintenance of resistance in the absence of antibiotic selection pressure. Empirical treatment of cases of complicated enteric fever returning from Pakistan will henceforth have to include a carbapenem.

Characterization of OXA-48-producing Klebsiella oxytoca isolates from a hospital outbreak in Tunisia

ObjectiveThere is very limited information about OXA-48-producing Klebsiella oxytoca. The aim of this study was to describe the phenotypic and molecular characterization of OXA-48-producing K. oxytoca isolates that caused an outbreak in a hospital in Tunisia. MethodsNineteen OXA-48-producing K. oxytoca were isolated from 2013 to 2016 in the University Hospital Farhat Hached, Sousse, Tunisia. Antibiotic susceptibility testing was performed by broth microdilution. Carbapenemase activity was investigated using the modified carbapenem inactivation method (mCIM). Phenotypic tests were also carried out to detect extended-spectrum β-lactamases. PCR was used to test for the presence of carbapenemase genes (blaIMP, blaVIM, blaNDM, blaSPM, blaAIM, blaDIM, blaGIM, blaSIM, blaKPC, blaBIC and blaOXA-48). Genetic relatedness among isolates was investigated using rep-PCR. Whole genome sequencing (WGS) was performed in three representative isolates. ResultsmCIM was positive in all isolates. None of the isolates presented an ESBL phenotype. All strains were susceptible to cefoxitin, ceftazidime, cefepime, aztreonam, imipenem, meropenem, fluoroquinolones, aminoglycosides and colistin, and resistant to piperacillin-tazobactam, ertapenem, ticarcillin and ampicillin-sulbactam. All isolates presented the blaOXA-48 gene located in a ca. 63 kb IncL plasmid, which carried no additional resistance genes. They belonged to the new ST220. ConclusionIsolates from this study did not co-express an ESBL, which could complicate their detection in clinical laboratories. As OXA-48 has been mostly reported in K. pneumoniae there is a risk that the production of this enzyme is not suspected in the less common species K. oxytoca. These difficulties could play an important role in the hidden spread of this enzyme.

Emergence of the New KPC-49 Variant Conferring an ESBL Phenotype with Resistance to Ceftazidime-Avibactam in the ST131-H30R1 Escherichia coli High-Risk Clone.

We report the emergence of an isolate belonging to the sequence type (ST)131-Escherichia coli high-risk clone with ceftazidime-avibactam resistance recovered from a patient with bacteremia in 2019. Antimicrobial susceptibility was determined and whole genome sequencing (Illumina-NovaSeq6000) and cloning experiments were performed to investigate its resistance phenotype. A KPC-3-producing E. coli isolate susceptible to ceftazidime-avibactam (MIC = 0.5/4 mg/L) and with non-wild type MIC of meropenem (8 mg/L) was detected in a blood culture performed at hospital admission. Following 10-days of standard ceftazidime-avibactam dose treatment, a second KPC-producing E. coli isolate with a phenotype resembling an extended-spectrum β-lactamase (ESBL) producer (meropenem 0.5 mg/L, piperacillin-tazobactam 16/8 mg/L) but resistant to ceftazidime-avibactam (16/4 mg/L) was recovered. Both E. coli isolates belonged to ST131, serotype O25:H4 and sublineage H30R1. Genomics analysis showed a core genome of 5,203,887 base pair with an evolutionary distance of 6 single nucleotide polymorphisms. A high content of resistance and virulence genes was detected in both isolates. The novel KPC-49 variant, an Arg-163-Ser mutant of blaKPC-3, was detected in the isolate with resistance to ceftazidime-avibactam. Cloning experiments revealed that blaKPC-49 gene increases ceftazidime-avibactam MIC and decreases carbapenem MICs when using a porin deficient Klebsiella pneumoniae strain as a host. Both blaKPC-3 and blaKPC-49 genes were located on the transposon Tn4401a as a part of an IncF [F1:A2:B20] plasmid. The emergence of novel blaKPC genes conferring decreased susceptibility to ceftazidime-avibactam and resembling ESBL production in the epidemic ST131-H30R1-E. coli high-risk clone presents a new challenge in clinical practice.

Prevalence and Antimicrobial Resistance of Gram-Negative Bacteria Isolates in Shellfish Samples from Two River Estuaries in South-South Nigeria

Antibiotic resistant bacteria pathogens remain the leading cause of shellfish borne diseases and a major health threat to humans worldwide. The objectives of this study were to isolate, identify, and determine the antibiotic resistance patterns of Gram-negative bacteria from shellfish. We analyzed a total of 540 shellfish (117 clams, 88 oysters, and 136 periwinkles) samples collected from different vendors at Iko and Douglas Creeks in Akwa Ibom State, South-South Nigeria. Conventional cultural techniques, morphological, biochemical characteristics, and PCR amplification were used to identify the bacterial isolates. Antibiotic susceptibility tests (Kirby-Bauer disk diffusion method) and ESBL phenotype (disk) of the isolates were performed. One hundred and thirty-five (135) Gram-negative bacteria comprising 5 genera and 14 species were detected at a prevalence of: Alcaligenes faecalis TRB-7 38 (28.2%), Pseudomonas oryzihabitans strain KCB005 16 (11.9%), Paenalcaligenes retgerii strain B5 12 (8.9%) Pseudomonas aeruginosa JB2 10 (7.4%), Providencia stuartii DMC-28b 9 (6.7%), Alcaligenes species TLT151 8 (5.9%), Pseudomonas aeruginosa CIFRI DTSB1 7 (5.2%), Paenalcaligenes species UN24 7 (5.2%), Alcaligenes faecalis BT10 7 (5.2%), Vibrio species strain PrVy108 6 (4.4%), Pseudomonas xiamenensis C10-2 5 (3.7%), Providencia vemicola Bu15_38 4 (2.9%), Pseudomonas anguillisceptica 4029 3 (2.2%), and Pseudomonas aeruginosa N15-01092 3 (2.2%). All tested isolates showed various degrees of resistance to the thirteen antimicrobials evaluated. High levels of resistance (100%) to cefepime and imipenem were expressed by all isolates except the Providencia species. For the EBSL indicators, all isolates apart from Alcaligenes species were resistant (100%) to ceftriaxone. All Vibrio species were susceptible to norfloxacin, nalidixic acid, and ceftazidime. The identification of antibiotic resistant Gram-negative bacteria (GNARB) from shellfish in this study highlights the risk of disseminated multi-drug resistance—a serious public health concern.

Molecular Identification of Co-Existence of Carbapenemase and Extended-Spectrum &amp;lt;i&amp;gt;β&amp;lt;/i&amp;gt;-Lactamase Genes in &amp;lt;i&amp;gt;Klebsiella pneumoniae&amp;lt;/i&amp;gt; Clinical Isolates, and Their Phylogenetic Patterns in Kenya

The increasing incidence of multidrug-resistant Klebsiella pneumoniae strains has become a serious global healthcare problem. Additionally, the carriage of both extended-spectrum ß-lactamase and carbapenemase genes on plasmid and genomic DNA in K. pneumoniae clinical isolates has not been documented in Kenya. This study aimed to assess the presence of extended spectrum β-lactamase (ESBL) and carbapenemase genes on genomic and plasmid DNA in K. pneumoniae, and classify these super-bug clinical isolates based on their phylogenetic patterns. The identification of Klebsiella-like clinical isolates (n = 20) collected from Kenyatta National Hospital in Nairobi was performed using API 20E Kit. Screening and confirmation for ESBL and carbapenemase phenotypes were conducted using Kirby-Bauer disk diffusion susceptibility test protocol. Conventional PCR technique was used to characterize ESBL and carbapenemase resistant genes on both genomic and plasmid DNA. Subsequently, 16S rRNA gene amplification and sequencing were performed. The 16S rRNA gene contiguous sequences of the bacterial isolates were analyzed using the ChromasPro. The gene sequence was compared with the sequences in GenBank database, using the BLAST program of NCBI to obtain the nearest phylogenetic neighbours from the databases. Then, the sequences of MDR K. pneumoniae and its relatives were aligned using ClustalW. The evolutionary history was inferred by using the maximum likelihood algorithm in MEGA MX. The phenotypic data of antibiotic susceptibility testing revealed that 2/20 (10%) clinical isolates were resistant both to imipenem and meropenem and producers of carbapenemase. These isolates were carbapenemase producers but not extended β-lactamases. However, 3/20 (15%) isolates that co-harboured blaNDM-1, blaIMP, blaTEM, and bla-OXA were identified during genotypic analysis. The positive control used separately yielded the expected band sizes for blaIMP (275 bp), blaOXA-48 (438 bp), and BlaKPC (798). The phylogenetic analysis showed the dual ESBL and carbapenemase producing Klebsiella pneumoniae could be classified as K. pneumoniae strain DSM 30104 and K. pneumonia subsp. pneumoniae strain GMH1080. This study confirmed the co-existence of ESBL and carbapenemase genes in Klebsiella pneumoniae on both bacterial genomic and Plasmid DNA, and demonstrated that the isolates are evolutionarily distinct. These findings raise a concern about the genotypic diversity of antibiotic resistance genes in bacterial isolates and their location. We, therefore, recommend an alternative management approach to combat these MDR bacterial isolates as well as frequent molecular surveillance programs to support antimicrobial stewardship.

Molecular characterisation of extended-spectrum β-lactamase-producing Escherichia coli and Salmonella isolated from poultry and poultry products in Egypt

Extended-spectrum β-lactamase (ESBL) producing E. coli and salmonellae have spread rapidly worldwide and pose a serious threat to human and animal health. The present study was conduct-ed to determine the prevalence of ESBL-producing E.coli and salmonellae, to perform molecular characterisation of the ESBL-related bla genes, including blaTEM, blaSHV and blaCTX, and the sus-ceptibilities of these bacteria to various antimicrobial agents. From a total of 300 poultry samples, 25 and 20 samples were recognised as Salmonella and E. coli, respectively by microbiological and molecular methods. All E. coli and Salmonella isolates were positive for an ESBL phenotype. Mo-lecular detection for antibiotic resistance gene revealed blaTEM in all isolates of salmonellae and E. coli (100%), while blaSHV was detected in 5 (20%) and 2 (10%) of salmonellae and E. coli isolates, respectively. None of the isolates contained blaCTX gene. Serotyping of Salmonella spp. in chick-ens revealed that S. enteritidis was the major isolates followed by S. Infantis (21.4%), S. Kentucky (14.2%) and S. Typhimurium, S. Kapemba, S. Newport, S. Vejle and S. Magherafelt were detected at 7.1% respectively. S. Infantis was the major isolate detected in chicks (60%), while in ducks S. Typhimurium and S. Blegdam were identified. In ducklings, S. Sinchew, S. Infantis and S. Sekon-di were equally prevalent. Only S. Newmexico was identified in poultry products. E. coli in chick-en were serotyped into O1, O8, O29, O125, O128 and O157. In chicks, O29 and O126 serotypes were detected. In poultry products only O8 was detected. The results indicate that ESBL frequen-cy has reached an alarming level in poultry isolates in Egypt, with TEM enzymes being the pre-dominant β-lactamases detected.

1262. Antimicrobial Activity of Gepotidacin against Clinical Isolates of Escherichia coli and Staphylococcus saprophyticus Collected Worldwide in 2019

BackgroundGepotidacin (GSK2140944) is a novel triazaacenaphthylene bacterial type II topoisomerase inhibitor in Phase 3 clinical development for the treatment of gonorrhea and uncomplicated urinary tract infections (UTI). This study reports on interim results from a global surveillance program to monitor the in vitro activity of gepotidacin and comparator agents when tested against contemporary Escherichia coli (EC) and Staphylococcus saprophyticus (SSAP) clinical isolates collected from patients with UTIs worldwide as part of the SENTRY Antimicrobial Surveillance Program.MethodsA total of 1,467 EC and 92 SSAP isolates were collected from 73 medical centers located in US (38), Europe (27), Asia-Pacific region (4), and Latin America (4). These isolates were tested for susceptibility by reference methods in a central laboratory (JMI Laboratories). MIC results for gepotidacin and comparators were interpreted as per US FDA and EUCAST criteria. Isolates were from UTIs, 70% of which were from ambulatory, outpatient, emergency, and family practice medical services.ResultsGepotidacin (MIC50/90, 2/4 mg/L) displayed activity against 1,467 EC isolates with 98.2% of all observed MICs ≤ 4 mg/L. Susceptibility rates of trimethoprim-sulfamethoxazole (TMP-SMX; MIC50/90, ≤ .12/ > 16 mg/L), ciprofloxacin (MIC50/90, 0.015/ > 4 mg/L), and amoxicillin-clavulanate (MIC50/90, 8/16 mg/L) were 67.1%, 72.9%, and 78.7% (CLSI), respectively. Greater susceptibility against EC isolates was seen for fosfomycin (MIC50/90, 0.5/1 mg/L; 99.0%S), nitrofurantoin (MIC50/90, 16/32 mg/L; 97.4%S), and meropenem (≤ 0.015/0.03 mg/L; 100%S). An ESBL phenotype was observed in 15.3% of EC isolates; gepotidacin (MIC50/90, 2/4 mg/L) remained active against these isolates. Gepotidacin (MIC50/90, 0.06/0.12 mg/L) also was active against 92 SSAP isolates, with 100% of MICs ≤ 0.25 mg/L. Susceptibility of SSAP isolates to TMP-SMX, ciprofloxacin, or nitrofurantoin was greater than 98.8% (CLSI), while fosfomycin showed little activity (MIC50/90, 64/ > 256 mg/L; 98.9% R [EUCAST]).ConclusionGepotidacin demonstrated potent activity against contemporary Escherichia coli, including ESBL-producing isolates and S. saprophyticus isolates collected worldwide.Table 1 Disclosures S. J. Ryan Arends, PhD, Allergan (Research Grant or Support)Cipla Ltd. (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support) Deborah Butler, n/a, GlaxoSmithKline (Employee) Nicole Scangarella-Oman, MS, GlaxoSmithKline plc. (Employee, Shareholder) Mariana Castanheira, PhD, 1928 Diagnostics (Research Grant or Support)A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Amplyx Pharmaceuticals (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Fox Chase Chemical Diversity Center (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Paratek Pharma, LLC (Research Grant or Support)Pfizer (Research Grant or Support)Qpex Biopharma (Research Grant or Support) Rodrigo E. Mendes, PhD, A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Basilea Pharmaceutica International, Ltd (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Department of Health and Human Services (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Pfizer (Research Grant or Support)

663. Improved Detection of ESBL and AmpC Beta-Lactamase Producing Isolates of Enterobacteriaceae in Pediatric Patients with Bloodstream Infections Using Combined Genotypic and Phenotypic Antimicrobial Susceptibility Testing

BackgroundInfections secondary to pathogens resistant to third-generation cephalosporins (3GC), such as extended-spectrum (ESBL) and AmpC β-lactamase (AmpC) producing Enterobacteriaceae, are increasing. Currently, there are no recommendations regarding identification of AmpC in Citrobacter, Enterobacter, Morganella and Serratia spp. (CEMS organisms). This study’s aim was to increase the detection of AmpC and ESBL producing Enterobacteriaceae in blood cultures from pediatric population by combining genotypic with phenotypic antimicrobial susceptibility testing (AST).MethodsAll first time Enterobacteriaceae isolates recovered from blood cultures of pediatric patients at CCHMC between January 2017 and December 2018 were evaluated. The Check-MDR CT103XL assay was used to determine the presence of AmpC and ESBL. AST was performed using the Vitek 2 platform. Phenotypic ESBL resistance was defined by resistant to either ceftriaxone of ceftazidime using CLSI breakpoints. Combined cefoxitin resistance with ceftriaxone or ceftazidime resistance was used to define phenotypic AmpC (EUCAST standards).ResultsThere were 170 isolates, from 147 patients, with 21 (12.4%) AmpC and 18 (10.6%) ESBL genes detected. Using AST, 11 (6.5%) and 26 (15.3%) isolates met AmpC and ESBL phenotypic criteria respectively. However, 14 of the isolates with AmpC genes detected and 2 of isolates with ESBL genes detected failed to meet phenotypic criteria. In addition, 4 (19%) of 21 AmpC isolates were susceptible to cefoxitin and 3GC while both E. coli and S. marcescens genotypic ESBL isolates were susceptible to 3GC.Number of AmpC- and ESBL- Producing Isolates Detected Using Phenotypic Method a,b, Genotypic Method and Combined Testing ConclusionWe identified 16 (9.4%) isolates with resistance genes detected but that failed to meet phenotypic criteria.Without molecular testing, patients with these isolates may have been treated with 3GC which could have resulted in treatment failure.The addition of genotypic testing to AST improved the identification of AmpC and ESBL organisms and provided clinically relevant data to guide treatment of resistant organisms. Combined testing is also beneficial for infection control and epidemiological purposes.Disclosures All Authors: No reported disclosures

1565. In Vitro Activities of Ceftaroline and Comparator Agents against Bacterial Pathogens Collected from Patients with Skin and Skin Structure Infections: ATLAS Global Surveillance Program 2012-2018

BackgroundCeftaroline fosamil, the prodrug of ceftaroline, is a parenteral cephem approved for the treatment of patients with skin and skin structure infections (SSSIs) caused by Staphylococcus aureus (both methicillin-susceptible [MSSA] and methicillin-resistant [MRSA] isolates), β-hemolytic streptococci (Streptococcus pyogenes, Streptococcus agalactiae), and select species of Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca). The current study is part of the ATLAS (Antimicrobial Testing Leadership and Surveillance) program and evaluated the current activities of ceftaroline and comparator agents against commonly encountered bacterial isolates associated with SSSIs.MethodsFrom 2012 to 2018 the ATLAS program received 90,119 bacterial isolates that had been cultured by 370 clinical laboratories in 56 countries from samples of patients diagnosed with SSSIs. All isolates were transported to IHMA, Inc., (Schaumburg, IL, USA) where their identities were confirmed using MALDI-TOF mass spectrometry and antimicrobial susceptibility testing performed following standardized CLSI broth microdilution methodology (M07). Percent susceptibilities were determined using 2020 CLSI MIC breakpoints. Phenotypic ESBL screening and confirmatory testing were performed using the CLSI M100 method.ResultsThe in vitro activity of ceftaroline is summarized in the following table. Overall, 100% of MSSA and 93.8% of MRSA from SSSI were susceptible to ceftaroline (MIC ≤1 µg/ml); 6.2% of MRSA isolates were ceftaroline -susceptible dose-dependent (MIC 2-4 µg/ml) with greatest proportion being from Chile (57.1% of 1,669 isolates), Thailand (36.5% of 2,318 isolates), and S. Korea (29.3% of 1,231 isolates). No ceftaroline-resistant MRSA were observed. All S. pyogenes and 88.5% of ESBL-negative Enterobacterales were also susceptible to ceftaroline.Table ConclusionCeftaroline continues to demonstrate potent in vitro activity against clinically relevant pathogens associated with SSSIs.Disclosures Greg Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor)

1594. Antimicrobial Resistance Monitoring through the ATLAS Global Surveillance Program 2012-2018

BackgroundAntimicrobial resistance is an increasingly serious threat to global public health. The Antimicrobial Testing Leadership and Surveillance (ATLAS) program has provided reliable, global, regional and local in vitro susceptibility data, including mechanisms of resistance, since 2004. In this analysis, data from the ATLAS program are used to measure the in vitro activity of several key gram-negative/gram-positive agents against major global pathogens.MethodsA total of 251,837 gram-negative and 132,363 gram-positive non-duplicate, clinical isolates were collected from multiple infection sources from 743 unique sites in 74 countries during 2012-2018 in the ATLAS program. Identification was confirmed to the species level using MALDI-TOF spectrometry. Only one clinically relevant causative isolate per patient was accepted into the study. MICs were determined by broth microdilution following CLSI guidelines and interpreted using 2020 CLSI breakpoints. Phenotypic ESBL screening and confirmatory testing were performed using the CLSI M100 method.ResultsThe in vitro activities of selected antimicrobial agents are provided in the table below. Based on percent susceptibility, ceftazidime-avibactam, amikacin, tigecycline, meropenem, and ceftolozane-tazobactam were the most active agents against most gram-negative isolates. The CRE rate among Enterobacterales isolates was 3.2%, with tigecycline and ceftazidime-avibactam the most active among this resistant subgroup. Ceftazidime-avibactam, ceftolozane-tazobactam, and amikacin were the most active agents against Pseudomonas aeruginosa. Ceftaroline, linezolid, tigecycline and vancomycin all showed good activity against gram-positive isolates.Table ConclusionCeftazidime-avibactam, ceftolozane-tazobactam, tigecycline, meropenem, and amikacin all showed good activity against a global collection of Enterobacterales. Ceftaroline, tigecycline, linezolid and vancomycin all exhibited excellent activity against gram-positive isolates. Continued monitoring of susceptibility patterns among common pathogens will provide useful information for determining treatment strategies.DisclosuresDaniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor) Michael Dowzicky, MS, M.T. A.S.C.P., Pfizer, Inc. (Employee)

Molecular detection of extended spectrum β-lactamase genes in Escherichia coli clinical isolates from diarrhoeic children in Kano, Nigeria.

The increase in antimicrobial resistance in developed and developing countries is a global public health challenge. In this context β-lactamase production is a major contributing factor to resistance globally. The aim of this study was to determine the prevalence of phenotypic and genotypic extended spectrum β-lactamases (ESBLs) in 296 E. coli isolates recovered from diarrhoeic children younger than five years in Kano whose susceptibility profile against 7 antimicrobials had been determined. The E. coli isolates were subjected to double disc synergy test for phenotypic ESBLs detection and ESBL associated genes (blaCTX-M, blaTEM and blaSHV) were detected using conventional PCR. Phenotypically, 12.8% (38/296) E. coli isolates presented a ESBLs phenotype, with a significantly higher proportion in isolates from females compared with males (P-value = 0.024). blaCTX-M 73.3% and blaTEM 73.3% were the predominant resistance genes in the ESBLs positive E. coli (each detected in 22/30 isolates, of which 14 harboured both). In addition, 1/30 harboured blaCTX-M + blaTEM + blaSHV genes simultaneously. This study demonstrates the presence of ESBLs E. coli isolates in clinically affected children in Kano, and demonstrates the circulation of blaCTX-M and blaTEM associated with those phenotypes. Enactment of laws on prudent antibiotic use is urgently needed in Kano.

Resistance among urinary tract pathogens collected in Europe during 2018

ObjectivesEscherichia coli, Klebsiella pneumoniae and Proteus mirabilis are urinary tract infection (UTI) pathogens and extended spectrum β-lactamase (ESBL)-producing pathogens exhibit co-resistance to oral fluoroquinolones (FQ) and trimethoprim-sulphamethoxazole (TMP-SMX). This study assessed the prevalence of ESBL phenotypes and co-resistance to FQ and TMP-SMX. MethodsIn total, 766 E. coli, 260 K. pneumoniae and 104 P. mirabilis from UTIs in 18 countries were evaluated for susceptibility in the SENTRY surveillance programme, and results interpreted using EUCAST criteria. ResultsE. coli, K. pneumoniae and P. mirabilis accounted for 57.1%, 11.3% and 7.8%, respectively, of the isolates. Among E. coli, resistance to levofloxacin and TMP-SMX ranged from 21.8% to 32.7% for all isolates increasing to 66.5–67.0% among those with a ESBL phenotype (17.9% of all UTI E. coli from Europe were ESBL phenotypes). In contrast, all E. coli were susceptible to meropenem. For K. pneumoniae, resistance rates for levofloxacin and TMP-SMX were 32.2–40.0% increasing to 69.1–78.6% for ESBL phenotypes. Meropenem was the most active agent, with 7.7% resistance. Among P. mirabilis resistance to levofloxacin and TMP-SMX was 26–38.5% and increased to 100% for ESBL phenotypes. No meropenem-resistant P. mirabilis were reported. ConclusionsHigh co-resistance rates were observed for oral antibiotics among ESBL phenotypes raising concerns regarding empiric use of FQ and TMP-SMX for treating resistant UTIs outside of the hospital. In contrast, intravenous carbapenems retain activity against resistant UTI pathogens. New oral options with the spectrum of the carbapenems would address an unmet need for managing resistant UTIs.

Retrospective Analysis on Antimicrobial Resistance Trends and Prevalence of β-lactamases in Escherichia coli and ESKAPE Pathogens Isolated from Arabian Patients during 2000-2020.

The production of diverse and extended spectrum β-lactamases among Escherichia coli and ESKAPE pathogens is a growing threat to clinicians and public health. We aim to provide a comprehensive analysis of evolving trends of antimicrobial resistance and β-lactamases among E. coli and ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acine to bacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) in the Arabian region. A systematic review was conducted in Medline PubMed on papers published between January 2000 and February 2020 on countries in the Arab region showing different antibiotic resistance among E. coli and ESKAPE pathogens. A total of n = 119,144 clinical isolates were evaluated for antimicrobial resistance in 19 Arab countries. Among these clinical isolates, 74,039 belonged to E. coli and ESKAPE pathogen. Distribution of antibiotic resistance among E. coli and ESKAPE pathogens indicated that E. coli (n = 32,038) was the predominant pathogen followed by K. pneumoniae (n = 17,128), P. aeruginosa (n = 11,074), methicillin-resistant S. aureus (MRSA, n = 4370), A. baumannii (n = 3485) and Enterobacter spp. (n = 1574). There were no reports demonstrating Enterococcus faecium producing β-lactamase. Analyses revealed 19 out of 22 countries reported occurrence of ESBL (Extended-Spectrum β-Lactamase) producing E. coli and ESKAPE pathogens. The present study showed significantly increased resistance rates to various antimicrobial agents over the last 20 years; for instance, cephalosporin resistance increased from 37 to 89.5%, fluoroquinolones from 46.8 to 70.3%, aminoglycosides from 40.2 to 64.4%, mono-bactams from 30.6 to 73.6% and carbapenems from 30.5 to 64.4%. An average of 36.9% of the total isolates were reported to have ESBL phenotype during 2000 to 2020. Molecular analyses showed that among ESBLs and Class A and Class D β-lactamases, blaCTX-M and blaOXA have higher prevalence rates of 57% and 52.7%, respectively. Among Class B β-lactamases, few incidences of blaVIM 27.7% and blaNDM 26.3% were encountered in the Arab region. Conclusion: This review highlights a significant increase in resistance to various classes of antibiotics, including cephalosporins, β-lactam and β-lactamase inhibitor combinations, carbapenems, aminoglycosides and quinolones among E. coli and ESKAPE pathogens in the Arab region.

Extended-Spectrum β-Lactamase-Producing Enterobacterales Shedding by Dogs and Cats Hospitalized in an Emergency and Critical Care Department of a Veterinary Teaching Hospital.

Extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) gut shedding in human medicine is considered as a major reservoir for ESBL-associated infections in high risk patients. In veterinary medicine, data regarding ESBL-PE gut shedding on admission to emergency and critical care department is scarce. We aimed to determine ESBL-PE shedding rates by dogs and cats in this setting and to determine the risk factors for shedding, at two separate periods, three-years apart. Rectal swabs were collected from animals, on admission and 72 h post admission, enriched and plated on Chromagar ESBL plates, followed by bacterial identification. ESBL phenotype was confirmed and antibiotic susceptibility profiles were determined (Vitek 2). Medical records were reviewed for risk factor analysis (SPSS). Overall, 248 animals were sampled, including 108 animals on period I (2015–2016) and 140 animals on period II (2019). In both periods combined, 21.4% of animals shed ESBL-PE on admission, and shedding rates increased significantly during hospitalization (53.7%, p-value < 0.001). The main ESBL-PE species were Escherichia coli and Klebsiella pneumoniae, accounting for more than 85% of the isolates. In a multivariable analysis, previous hospitalization was a risk factor for ESBL-PE gut shedding (p-value = 0.01, Odds ratio = 3.05, 95% Confidence interval 1.28–7.27). Our findings demonstrate significant ESBL-PE gut shedding among small animals in the emergency and critical care department, posing the necessity to design and implement control measures to prevent transmission and optimize antibiotic therapy in this setting.

Occurrence and Characteristics of the Extended-spectrum Beta-lactamase-producing Enterobacterale in a Hospital Setting

Objectives:Infectious diseases caused by ESBL-producingEnterobacteraleare an emerging problem worldwide, which increase hospital costs, empirical treatment failure, together with rates of morbidity and mortality. The aims of this study were to determine the antibiotic-resistant patterns and the frequency ofblaTEM,blaCTX-M andblaSHV genes amongEnterobacterale.Methods:A total of 239 non-repeated clinical isolates of theEnterobacteralefamily, including 202 (84.5%)Escherichia coliandKlebsiella pneumoniae25 (12.3%) were collected. Identification and susceptibility tests were carried out on 60 (25.9%) ESBL phenotypes using biomérieux VITEK®2 compact system. Isolates showing ESBL positivity by the phenotypic method were all screened forblaTEM,blaCTX-M andblaSHV genes by PCR.Results:The prevalence of ESBL-producingEnterobacteraleisolates was found to be 25.9%. These ESBL-producing isolates displayed an increasing rate of resistance for aminopenicillins (ampicillin) (96.3%), followed by piperacillin-tazobactam (54.2%), amoxicillin/clavulanic acid (45.8), the cephalosporin groups, ceftriaxone (52.4%), ceftazidime (46.7%), and fluoroquinolone (ciprofloxacin) (42.7%). Both the organisms showed a higher susceptibility to the carbapenems (Imipenem) and aminoglycosides (Amikacin). Out of the 62 ESBL positive isolates, 11 (17.7%) carried the TEM gene, 22 (35.5%) carried the CTX-M gene alone, 8 (12.9%) carried both TEM and CTX-M genes, 1(1.6%) carried both SHV and CTX-M genes, and 20 (32.3%) carried the TEM, SHV, and CTX-M genes. SHV gene alone was not reported in any of the isolates.Conclusion:The study indicated a moderate occurrence of ESBL-producingEnterobacteralewith CTX-M being the most dominant gene. The co-existence of all three genes on many occasions suggested the carriage of multiple plasmids with three resistance genes that might pose a serious epidemiological, clinical and public health threat.