Imipenem Resistance Research Articles

Molecular characterization of extended-spectrum β-lactamases-producing Enterobacteriaceae species in ground beef and chicken meat

The objectives of this study were i) to characterize extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) using pheno- and genotyping methods, ii) to evaluate the antimicrobial resistance pattern against 10 antibiotics, and iii) to investigate class 1 integron (intI1) in 80 Enterobacteriaceae isolates obtained from chicken meat (n = 40; 47 isolates) and ground beef (n = 40; 33 isolates) samples. Through the study, we found that 55 (68.7 %) of 80 Enterobacteriaceae isolates were capable of β-lactamase activity, and 38 (47.5 %) of them were multi-drug-resistant (MDR). The ground meat-origin isolates are 1.2 times more likely to produce imipenem resistance compared to chicken-meat-origin isolates (z = 2.1, p < 0.05, OR = 1.42). ESBL-E was found in 18 (22.5 %) of the isolates, 16.3 % of chicken meat and 6.3 % of ground beef origin. The bla genes were detected in 14 isolates [bla-TEM (n = 10; 12.5 %); bla-SHV (n = 4; 5.0 %); bla-CTX-M (n = 0)], where the predominant species were Escherichia (E.) coli and Citrobacter braakii. The nine ESBL-E isolates were MDR. Twenty-eight (35.0 %) of 80 isolates were found to be resistant to at least one third-generation cephalosporin, and eight (28.6 %) of them were also ESBL-E. Eleven of 16 (48.5 %) carbapenem-resistant isolates were ESBL-E. The intI1 gene was found in 13 (16.3 %) isolates, five of which were ESBL-E, and four of which were MDR. Co-existing with bla-TEM and the intI1 isolate was ESBL-E. coli, which was resistant to nine antibiotics. In conclusion, chicken meat and ground beef may pose a potential risk of containing ESBL-E, and bla genes which could be spread to the entire food chain.

Epidemiological and Genetic Characteristics of Clinical Carbapenem-Resistant Pseudomonas aeruginosa Strains in Guangdong Province, China.

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a bacterial pathogen that may cause serious drug-resistant infections that are potentially fatal. To investigate the genetic characteristics of these organisms, we tested 416 P. aeruginosa strains recovered from 12 types of clinical samples collected in 29 different hospital wards in 10 hospitals in Guangdong Province, China, from 2017 to 2020. These strains were found to belong to 149 known sequence types (STs) and 72 novel STs, indicating that transmission of these strains involved multiple routes. A high rate of resistance to imipenem (89.4%) and meropenem (79.4%) and a high prevalence of pathogenic serotypes (76.4%) were observed among these strains. Six STs of global high-risk clones (HiRiCs) and a novel HiRiC strains, ST1971, which exhibited extensive drug resistance, were identified. Importantly, ST1971 HiRiC, which was unique in China, also exhibited high virulence, which alarmed the further surveillance on this highly virulent and highly resistant clone. Inactivation of the oprD gene and overexpression of efflux systems were found to be mainly responsible for carbapenem resistance in these strains; carriage of metallo-β-lactamase (MBL)-encoding genes was less common. Interestingly, frameshift mutations (49.0%) and introduction of a stop codon (22.4%) into the oprD genes were the major mechanisms of imipenem resistance. On the other hand, expression of the MexAB-OprM efflux pump and MBL-encoding genes were mechanisms of resistance in >70% of meropenem-resistant strains. The findings presented here provide insights into the development of effective strategies for control of worldwide dissemination of CRPA. IMPORTANCE Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a major concern in clinical settings worldwide, yet few genetic and epidemiological studies on CRPA strains have been performed in China. Here, we sequence and analyze the genomes of 416 P. aeruginosa strains from hospitals in China to elucidate the genetic, phenotypic, and transmission characteristics of CRPA strains and to identify the molecular signatures responsible for the observed increase in the prevalence of CRPA infections in China. These findings may provide new insight into the development of effective strategies for worldwide control of CRPA and minimize the occurrence of untreatable infections in clinical settings.

Rapid identification of canine uropathogens by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and the clinical factors that correlated bacterial species and antimicrobial resistance.

Using the matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) method for bacterial diagnosis, rapid urine sample preparation can reduce time relapsing of diagnosis and improve discriminatory power in coinfection cases. We aimed to evaluate rapid urine preparation procedures before MALDI-TOF MS application using dog clinical urine samples in comparison with standard microbiological diagnostic methods by agreement analysis. We determined the frequency and distribution of bacteria and bacterial resistance and their correlations to clinical history. Three experimental procedures comprising direct centrifugation, 10% sodium dodecyl sulfate digestion, and ultrasonic preparation were performed for method validation and sensitivity. Sterile urine containing Escherichia coli and/or Staphylococcus aureus were used as simulated samples. By ultrasonic preparation, the microorganisms could be detected 1.46-1.51 × 105 CFU, which was considered the most suitable technique. This preparation was significantly consistent with the routine method based on data from Hospital Information Systems for 50 urine samples from canine cystitis. By standard protocol, Enterobacteriaceae and Staphylococcus pseudintermedius were found in most of the 155 urine samples with cystitis. Extended-spectrum beta-lactamase-producing Enterobacteriaceae was found in 25-30% of the samples. Imipenem resistance was found in 70% of Acinetobacter baumannii cases; almost all were resistant to second-generation fluoroquinolones and tetracyclines. The most efficient antibiotic for treating bacterial urinary tract infection was amoxicillin plus clavulanic acid. A. baumannii and Pseudomonas aeruginosa were susceptible to pradofloxacin. Prolonged urine catheterization was linked to lower urinary tract infections by Enterobacter spp., which also correlated with chronic kidney disease.

Molecular characterization of antibiotic resistance, aminoglycoside and PmrA genes among foodborne and clinical Acinetobacter spp.

The assessment of antibiotic resistance and related genes of foodborne Acinetobacter spp. and the analysis of whether they are genetically related to clinical infection-agent strains are crucial in terms of sustainability of food safety. The study at hand investigated antibiotic resistance, aminoglycoside-modifying enzyme (AME), and colistin resistance (PmrA) genes, clonal relationships while evaluating a possible correlation between antibiotic resistance and related genes between 27 foodborne and 50 clinical Acinetobacter spp. in Turkey. Antimicrobial susceptibilities, (AME), PmrA genes, and clonal relatedness of the strains were performed by disc diffusion, PCR, and Pulsed Field gel Electrophoresis (PFGE) methods, respectively. The aph-AI, aph-6, anth (3’’)-I, aadA1, aadB and PmrA genes were found as (24, 48%), (11, 22%), (7, 14%), (1, 2%), (2, 4%), and (46, 92%) respectively in clinical strains. This rate was found as (14, 51.9%), (16, 59.3%), (19, 70.4%), (2, 7.4%), (0, 0%), and (27, 100%) respectively in foodborne isolates. A positive correlation existed between the number of aph-AI gene positivity and trimethoprim-sulfamethoxazole and gentamycin resistance; anth (3’’)-I gene positivity, and colistin resistance; PmrA gene positivity and piperacillin-tazobactam, ceftazidime, meropenem, amikacin, and imipenem resistance in clinical strains (P

Prevalence and Characterization of Beta-Lactam and Carbapenem-Resistant Bacteria Isolated from Organic Fresh Produce Retailed in Eastern Spain

Fresh fruits and vegetables are potential reservoirs for antimicrobial resistance determinants, but few studies have focused specifically on organic vegetables. The present study aimed to determine the presence of third-generation cephalosporin (3GC)- and carbapenem-resistant Gram-negative bacteria on fresh organic vegetables produced in the city of Valencia (Spain). Main expanded spectrum beta-lactamase (ESBL)- and carbapenemase-encoding genes were also detected in the isolates. One hundred and fifteen samples were analyzed using selective media supplemented with cefotaxime and meropenem. Resistance assays for twelve relevant antibiotics in medical use were performed using a disc diffusion test. A total of 161 isolates were tested. Overall, 33.5% presented multidrug resistance and 16.8% were resistant to all β-lactam antibiotics tested. Imipenem resistance was observed in 18% of isolates, and low resistance levels were found to ceftazidime and meropenem. Opportunistic pathogens such as Acinetobacter baumannii, Enterobacter spp., Raoultella sp., and Stenotrophomonas maltophilia were detected, all presenting high rates of resistance. PCR assays revealed blaVIM to be the most frequently isolated ESBL-encoding gene, followed by blaTEM and blaOXA-48. These results confirm the potential of fresh vegetables to act as reservoirs for 3GC- and carbapenem-producing ARB. Further studies must be carried out to determine the impact of raw organic food on the spread of AMRs into the community.

Prediction of genome-wide imipenem resistance features in Klebsiella pneumoniae using machine learning.

Introduction. The resistance rate of Klebsiella pneumoniae (K. pneumoniae) to imipenem is increasing year by year, and the imipenem resistance mechanism of K. pneumoniae is complex. Therefore, it is urgent to develop new strategies to explore the resistance mechanism of imipenem for its effective and accurate use in clinical practice.Hypothesis/Gap sStatement. Machine learning could identify resistance features and biological process that influence microbial resistance from whole-genome sequencing (WGS) data.Aims. This work aimed to predict imipenem resistance genetic features in K. pneumoniae from whole-genome k-mer features, and analyse their function for understanding its resistance mechanism.Methods. This study analysed WGS data of K. pneumoniae combined with resistance phenotype for imipenem, and established K. pneumoniae to imipenem genotype-phenotype model to predict resistance features using chi-squared test and random forest. An external clinical dataset was used to verify prediction power of resistance features. The potential genes were identified through alignment the resistance features with the K. pneumoniae reference genome using blastn, the functions of potential genes were further analysed to explore its resistance-related signalling pathways with GO and KEGG analysis, the resistance sequence patterns were screened using streme software. Finally, the resistance features were combined and modelled through four machine-learning algorithms (logistic regression, SVM, GBDT and XGBoost) to evaluate their phenotype prediction ability.Results. A total of 16 670 imipenem resistance features were predicted from genotype-phenotype model. The 30 potential genes were identified by annotating the resistance features and corresponded to known antibiotic-related genes (mdtM, dedA, rne, etc.). GO and KEGG pathway analyses indicated the possible association of imipenem resistance with metabolism process and cell membrane. CRYCAGCDN and CGRDAAAN were found from the imipenem resistance features, which were widely presented in the reported β-lactam resistance genes (bla SHV, bla CTX-M, bla TEM, etc.), and YCYAGCMCAST with metabolic functions (organic substance metabolic process, nitrogen compound metabolic process and cellular metabolic process) was identified from the top 50 resistance features. The 25 resistance genes in the training dataset included 19 genes in the external dataset, which verified the accuracy of prediction. The area under curve values of logistics regression, SVM, GBDT and XGBoost were 0.965, 0.966, 0.969 and 0.969, respectively, indicating that the imipenem resistance features have a strong prediction power.Conclusion. Machine-learning methods could effectively predict the imipenem resistance feature in K. pneumoniae, and provide resistance sequence profiles for predicting resistance phenotype and exploring potential resistance mechanisms. It provides an important insight into the potential therapeutic strategies of K. pneumoniae resistance to imipenem, and speed up the application of machine learning in routine diagnosis.

Detection of Carbapenem-resistance in CRE by Comparative Assessment of RAPIDEC® CARBA NP and Xpert™Carba-R Assay.

Carbapenem-resistant Enterobacteriaceae (CRE) infections resist nearly most available antimicrobials, resulting in poor clinical outcomes. Saudi Arabia has a relatively high CRE prevalence. This study aims to evaluate the sensitivity of Rapidec Carba NP test and GeneXpert Carba-R assay compared with conventional manners for detection of carbapenemase-producing Enterobacteriaceae. This is a cross-sectional study including a total of 90 CRE isolates examined at two tertiary hospitals in KSA from October 2020 to December 2021. Gram-negative Enterobacteriaceae were identified by using Vitek 2 system and were furtherly tested for imipenem and meropenem susceptibility by E- test strips, followed by Rapidec Carba NP test and the Xpert™Carba-R assay. Carbapenem-resistant K. pneumoniae (78.9%) and carbapenem-resistant E. coli (14.4%) were the two most common isolates species. Colistin (98.9%) and tigecycline (88.9%) were the most effective antibiotics against CRE isolates, followed by amikacin (52.2%), gentamicin (33.3%), cotrimoxazole (15.6%), and ciprofloxacin (8.9%). blaOXA-48 was the predominant carbapenemase gene (44.4%), followed by blaNDM (32.2%). blaKPC gene was not detected. The Rapidec Carba NP and the Xpert™Carba-R demonstrated an overall sensitivity of 69.3% and 88%, respectively, in comparison to gold standard detection of meropenem and imipenem resistance by Vitek 2 system and E- test strips. RAPIDEC® CARBA NP may be a beneficial screening test for detecting CRE, but for confirmation of the results, Xpert Carba-R assay is more sensitive, significantly lowering the turnaround time compared to reference traditional methods. The information on carbapenemase genes may be used for epidemiologic purposes and outbreak management.

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Fresh fruits are popular sources of healthy diets with low energy density. Since they are consumed raw, it may act as a source of foodborne disease and a reservoir for antibiotic-resistant organisms. This study aimed to determine microbial prevalence among the fruits sold around hospital along with antimicrobial profiles. Thirty-five different types of fruits were bought from around Dhaka Medical College and Hospital (DMCH) and analyzed for the presence of bacteria. Antibiotic sensitivity, detection of ESBL, AmpC &beta;-lactamase, and MBL positive strains were done by standard methods followed by PCR to detect ESBL, AmpC &beta;-lactamase and MBL genes. Twenty-seven different organisms were isolated: Klebsiella spp. (33.33%), Citrobacter spp. (29.64%), Enterobacter spp. (22.22%), Escherichia coli (11.11%) and Staphylococcus aureus (3.70%). Among them, 48.15% were resistant to different antibiotics. Only one organism (Citrobacter spp.) produced ESBL phenotypically (7.69%). Two (15.38%) were positive for AmpC &beta;-lactamase and one of these (Enterobacter spp.) possessed SHV and CTX-M15A genes by PCR. Imipenem resistance was 84.62% of the antibiotic-resistant organisms and 10 (90.91%) were phenotypically MBL positive. By PCR, one Enterobacter spp. had MBL encoding gene OXA-48.&nbsp; Fresh fruits, contaminated with pathogens, might be a source of resistant organisms&#39; transmission and contribute to public health issues. &nbsp; Key words: Antibiogram, bacteria, Bangladesh, fresh fruits, fruit venders around hospital.

Evaluation of and risk factors for the metallo-beta-lactamase enzyme with respect to production of carbapenem-resistant Pseudomonas and Acinetobacter species

Purpose: To investigate the frequency of MBLs in Pseudomonas and Acinetobacter species with E-test, to determine the risk factors and to evaluate the demographic and clinical features of infected patients. Materials and methods: Imipenem or meropenem resistance of Pseudomonas and Acinetobacter isolated from several clinical samples with conventional methods were evaluated with imipenem EDTA E-test and the presence of Metallo-β-lactameses MBL was examined. Several isolates were screened for VIM-1, VIM-2, IMP-1, and IMP-2 with a PCR test. Results: Of 46 carbapenem resistant Acinetobacter isolates, 41 (89%), as well as of 19 carbapenem resistant Pseudomonas isolates, 5 (26%) had MBL positivity with imipenem-EDTA E-test. A history of Intensive Care Unit stay, mechanical ventilation and cephalosporin use were found to be significant risk factors with respect to MBL production. Conclusion: Detection of MBL production in Acinetobacter and Pseudomonas species especially in ICU patients is of prime importance to control infection rapidly and effectively, which contribute to prevention of outbreaks.

Changing Epidemiology of Pathogenic Bacteria Over the Past 20 Years in Korea.

The epidemiology of pathogenic bacteria varies according to the socioeconomic status and antimicrobial resistance status. However, longitudinal epidemiological studies to evaluate the changes in species distribution and antimicrobial susceptibility of pathogenic bacteria nationwide are lacking. We retrospectively investigated the nationwide trends in species distribution and antimicrobial susceptibility of pathogenic bacteria over the last 20 years in Korea. From 1997 to 2016, annual cumulative antimicrobial susceptibility and species distribution data were collected from 12 university hospitals in five provinces and four metropolitan cities in South Korea. The prevalence of Staphylococcus aureus was the highest (13.1%) until 2012 but decreased to 10.3% in 2016, consistent with the decrease in oxacillin resistance from 76.1% in 2008 to 62.5% in 2016. While the cefotaxime resistance of Escherichia coli increased from 9.0% in 1997 to 34.2% in 2016, E. coli became the most common species since 2013, accounting for 14.5% of all isolates in 2016. Pseudomonas aeruginosa and Acinetobacter baumannii rose to third and fifth places in 2008 and 2010, respectively, while imipenem resistance increased from 13.9% to 30.8% and 0.7% to 73.5% during the study period, respectively. Streptococcus agalactiae became the most common pathogenic streptococcal species in 2016, as the prevalence of Streptococcus pneumoniae decreased since 2010. During the same period, pneumococcal penicillin susceptibility decreased to 79.0%, and levofloxacin susceptibility of S. agalactiae decreased to 77.1% in 2016. The epidemiology of pathogenic bacteria has changed significantly over the past 20 years according to trends in antimicrobial resistance in Korea. Efforts to confine antimicrobial resistance would change the epidemiology of pathogenic bacteria and, consequently, the diagnosis and treatment of infectious diseases.

Evaluation of Antibiotic Resistance and adeABC, adeR, adeS Efflux Pump Genes among Foodborne and Clinical Acinetobacter spp. in Türkiye.

The adeABC efflux pump has a crucial role in the resistance of Acinetobacter baumannii strains to antimicrobial agents; it is encoded by adeABC, adeR, adeS genes. We evaluated antibiotic resistance, efflux pump genes, clonal relationships, and analyzed a probable correlation that can exist between antibiotic resistance and the aforementioned genes. We conducted this study on 27 food-originated and 50 human clinical Acinetobacter spp. in Southern Türkiye. MALDI-TOF system and disc diffusion/agar dilution (colistin) methods were used for the identification and antibiotic susceptibility. The efflux pump genes and genetic relatedness of the two groups were investigated by (PCR) and (PFGE) methods. Foodborne A. dijkshoorniae strain was multidrug- resistant (MDR), and none of them resistant to colistin. Most of the clinical isolates (92%) were Extensive-Drug Resistant (XDR); highest resistant to ceftazidime, piperacillin-tazobactam, and imipenem (47, 94%), and were lowest to colistin (7, 14%), respectively. adeABC, and adeR, adeS genes were (23, 85.2%), (9, 33.3%), (27, 100%) and (10, 37.3%), (18, 66.7%) in foodborne strains respectively. These rates were (43, 86%), (48, 96%), (50, 100%), and (34, 68%), (48, 96.7%) in clinical strains respectively. A positive correlation existed between adeA gene positivity and piperacillintazobactam, ceftazidime, gentamycin, imipenem (P=0.048), amikacin (P=0.007) and trimethoprimsulfamethoxazole (P=0.029) resistance in clinical strains. A positive correlation of trimethoprimsulfamethoxazole resistance and adeS gene positivity was seen in foodborne strains (P=0.018). Multiple-efflux pump genes rise in parallel to multidrug-resistance in clinical isolates, while susceptible to diverse antibiotics; food may be a potential provenance for the dissemination of adeABC, adeR and adeS genes.

Phenotypic Detection of Carbapenem Resistance in Clinical Isolate of Klebsiella Pneumoniae in Tertiary Care Hospital

The emergence and rapid spread of Multidrug resistant isolates of Klebsiella pneumoniae causing nosocomial infections, which require the great afford for the treating the patients by the clinician. The emergence of Metallo β-lactamase (MBL) producing isolates poses a challenge to routine microbiology laboratories. The purpose of this study was to assess the accuracy of various phenotypic methods for detecting MBL production among K. pneumoniae isolate. The current study may provide the necessary data to formulate a hospital antibiotic policy and to prevent the spread of multidrug resistance in the community. Total 240 K. pneumoniae isolates were included in our study which was isolated from various clinical samples from patients visiting a tertiary care hospital in central India. A total of 148 (61.7%) of K. pneumoniae were isolated from male patients whereas 92 (38.3%) isolates were from female patients. Out of 240 K. pneumoniae, 102 (42.5%) was detected Imipenem resistance by conventional (Kirby-Bauer) disc diffusion method which was confirmed by minimum inhibitory concentration (MIC) test (Epsilometer test). By the MIC Carbapenem resistance K. pneumoniae were confirmed for MBL producer by using phenotypic test. Combined disc synergy test (CDST) (Imipenem 10 mcg and Imipenem 10mcg + 0.5 m EDTA) and Modified Hodge test (MHT).The MHT test found most sensitive approach for detecting MBL in K. pneumoniae. This procedure is simple and clear and it may use in routine clinical labs for detection of MBL because carbapenems are last resort for treating bacterial infections. In recent years, carbapenem resistance has rampantly increased across the globe.

143. Genomics analysis of Carbapenem resistance in BCC Identify PenR E151V substitution and novel Burkholderia cepacia complex specific OXA-1043 subgroup

Abstract Background Treatment options for Burkholderia cepacia complex (Bcc) remain limited, and previous study revealed 26% of strains was susceptible to meropenem. In B. cenocepacia and many Bcc species, ampC and its regulator, ampR, named penR in Burkholderia genomes are not associated, sharing a divergent promoter, as in other previously studied species. Recently, Josselin Bodilis et el (2018) found that there was no different in genetic organization between imipenem-sensitive and imipenem-resistant strains. Our study is to provide an answer to the different of genetic expression pattern between imipenem resistance and imipenem sensitive Burkholderia cepacia complex species. Methods The Bcc species genome was deeply sequenced using Nanopore technology. Protein-coding genes, and coding and non-coding RNAs in the chromosomes and plasmids were annotated via the NCBI PGAP pipeline. Antibiotic-resistant genes (ARGs) were predicted by aligning protein-coding genes against the Comprehensive Antibiotic Resistance Database (CARD) using Diamond. Results In our study, drug susceptibility test of different antibiotic showed only Burkholderia cenocepacia strain MC0-3 revealed sensitive to imipenem (Table 1). Further genetic organization between imipenem-resistance and imipenem-sensitive strains showed similar β-lactamase-encoding genes (Figure 1). In the multiple sequence alignment of PenR, nine imipenem-resistance Bcc stains, which amino acid sequence at position 151 is glutamic acid, however, in imipenem-sensitive strain amino acid substitute glutamic acid with valine (Figure 2b). PROVEAN also showed amino acid substitutions at position E151 in PenR is deleterious (Table 2). We also analyzed 95 strains of Burkholderia, and drew the phylogenetic tree which showed PenR E151V subsititution consisted in other imipenem-sensitive strains of Burkholderia. In addition, a novel Burkholderia cepacia complex specific OXA-1043 subgroup is found in stain toggle 2, toggle 3 and toggle 4 (Figure 3). Figure 1.Genetic organization of imipenem resistance and imipenem sensitive in different strain of Burkholderia cepacia complex. Conclusion The results of this study indicate that antibiotic resistance related to the amino acid substitutions, which may explain the imipenem-sensitive strain of Burkholderia cenocepacia. Bedsides, a new OXA family is found in Burkholderia cenocepacia strain, and is named OXA 1403. Figure 2.Multiple sequence alignment PenR in different strains of Burkholderia cepacia complex and phylogenetic tree of Burkholderia spp. Disclosures All Authors: No reported disclosures.

1736. Xeruborbactam (QPX) Potentiates the Activity of Multiple β-Lactams Against Highly Resistant Pseudomonas aeruginosa to a Greater Degree than Other β-Lactamase Inhibitors

Abstract Background Pseudomonas aeruginosa (PA) is an important pathogen notorious for antibiotic resistance. Xeruborbactam (QPX) is a potent ultra-broad-spectrum boronic acid β-lactam inhibitor (BLI) that, in combination with selected BL antibiotics, has excellent in vitro activity against carbapenem-resistant Enterobacterales (CRE), and Acinetobacter baumanii or PA producing class A/B or D carbapenemases. We evaluated QPX in combination with anti-pseudomonal BLs against clinical PA isolates from tertiary care US hospitals. Methods We tested PA clinical isolates resistant to ≥1 BL (imipenem (IMP), meropenem (MEM), cefepime (FEP), piperacillin-tazobactam (PIP-TAZ), aztreonam (ATM), ceftolozane-tazobactam (TOL-TZP), ceftazidime-avibactam (CZA), IMI-relebactam (IMI-REL), MEM-vaborbactam (MVB)) against QPX (in fixed concentration of 8 µg/mL) combined with anti-pseudomonal BLs. We performed whole-genome sequencing on isolates using the MiSeq platform (Illumina). Results Antibiograms and resistance determinants of 77 isolates tested to date are summarized in Figs 1, 2. 91% of isolates were CR; 43%, 58% and 61% were resistant to CZA, IMI-REL and MVB, respectively. No isolates produced class A/B/D carbapemases. All except 2 isolates carried PDC variants. 92% either had oprD porin single nucleotide polymorphism (SNP) or deletions. mutS mutations (present in 23% of isolates) were associated with resistance to IPM/QPX (p=.04), but not TOL-QPX or PIP-QPX. Addition of QPX significantly reduced MIC50 of IPM (32-fold), PIP (16-fold), FEP and ATM (4-fold) (all p&amp;lt; .0001, Fig 3). Addition of QPX to MEM or TOL reduced MIC50 by 2-fold (p=.02, p&amp;lt; .0001). QPX reduced IMP and PIP MICs more than did REL (32 vs 8-fold, p&amp;lt; .0001) or TZP (16 vs nil, p=.0007), respectively. Addition of QPX reduced BL resistance, especially for TOL, PIP and IMP (Fig 4). We identified factors associated with BL/QPX resistance by logistic regression; for IMP/QPX: IMP resistance (p=.001), SNP in mexB (p=.01); for TOL/QPX: TOL resistance (p=.02); for PIP/QPX (SNP in mexR and mexB (p=.03). Conclusion QPX enhanced the activity of BLs, especially TOL and PIP, against PA with baseline resistance to BL, more so than other BLIs. TOL/QPX and PIP/QPX are less impacted by PA efflux and porin mutations than IMP/QPX. Disclosures Cornelius J. Clancy, MD, receives research funding paid to his institution from Astellas and Merck: Grant/Research Support|serves as an advisory Board member for Astellas, Cidara, and Scynexis, served on the advisory board for Merck, Qpex Biopharma, and Shionogi: Advisor/Consultant|Venatorx and Needham &amp; Associates: Advisor/Consultant.

The Emergence of Colistin- and Imipenem-Associated Multidrug Resistance in Escherichia coli Isolates from Retail Meat.

To determine the prevalence of Escherichia coli and their drug resistance profiles in fresh pork sold at two retail outlets (open-air market and closed retail stores) in Alice, South Africa. Retail meat samples (n = 176) collected from four shops (two from open-air markets and two from closed stores) were analyzed by conventional biochemical and PCR-based molecular confirmatory tests. The confirmed isolates were profiled for antimicrobial susceptibility to a panel of 12 commercial antibiotics: tetracycline, ampicillin, sulphamethoxazole trimethoprim, erythromycin, gentamycin, colistin sulphate, cefotaxime, chloramphenicol, norfloxacin, ciprofloxacin, cefuroxime, and imipenem. Colistin, ampicillin, and erythromycin resistance genes were profiled with the gene-specific primers. Multidrug resistance (MDR) and the association of imipenem and colistin in the MDR profile were determined. A total of 68 (39.08%) E. coli isolates were confirmed by PCR analysis. Resistance was most common to erythromycin (100%), followed by cefotaxime (95.58%), ampicillin (88.23%), cefuroxime (88.23%), trimethoprim-sulphamethoxazole (88.23%), and tetracycline (60.29%). Overall, 27/68 (39.70%) were MDR (≥ 3antibiotics classes). MDR E. coli isolates associated with imipenem resistance (50.00%) and colistin resistance (33.82%) were detected. The resistance genes were detected among the isolates though not in all the phenotypically resistant isolates. The detection of colistin resistance among MDR E. coli isolates from retail meat is troubling as the drug is a last resort antibiotic. Overall, the epidemiological implications of the findings are of public health importance.

An Alliance of Carbapenem-Resistant Klebsiella pneumoniae with Precise Capsular Serotypes and Clinical Determinants: A Disquietude in Hospital Setting

Carbapenemase-resistant Klebsiella pneumoniae (CRKP) is a genuine burden for physicians and researchers. We aimed at carbapenemase resistance and its relation with capsular serotyping in K. pneumoniae and studied some clinical determinants, which may influence the clinical infections. Initially, 61 K. pneumoniae isolates obtained from various clinical specimens were confirmed at the molecular level and then antimicrobial susceptibility test was performed followed by capsular serotyping performed by multiplex PCR. All isolates were subjected to the detection of carbapenemase genes including bla KPC, bla NDM-1, bla OXA-48, bla VIM, and bla IMP. Clinical and demographic data of all patients were reviewed including age, gender, underlying diseases, and the treatment obtained. Multidrug-resistance was a predominant feature in 77% K. pneumoniae strains. Presence of extended-spectrum beta-lactamase was detected phenotypically in 59% K. pneumoniae strains. Carbapenem resistance was noticed phenotypically in 24.6% isolates. bla OXA-48 and bla NDM-1 were the most frequent carbapenemase genes. bla NDM-1 positive isolates correlated with gentamicin, amikacin, imipenem, and meropenem resistance (p < 0.05). The nosocomial isolates mostly harbored bla OXA-48 gene (p < 0.02). Amongst all the K. pneumoniae isolates, 59% isolates could be typed and serotype K54 had the highest prevalence followed by K20 and K5. Correlation between the carbapenemase genes, serotype and type of infection showed that bla OXA-48 positive strains had a significant association with K20 serotype and urinary tract infections (p=0.2) while, K20 serotype and bla KPC positive strains were significantly associated with wound infections (K20, p=0.3 and bla KPC, and p=0.4). Mucoid phenotype was not found related to presence of specific carbapenemase genes or serotypes except serotype K20 (p < 0.001). Patients with monotherapy had treatment failure in comparison to the combination therapy for bla KPC-associated infections. In conclusion, the present investigation exhibited the significant association between K20 serotype with bla OXA-48. The predominance of K54 reveals the possibility of endemicity in our hospital setting. K. pneumoniae isolated from wound specimens significantly harbors K20 serotype and bla KPC gene. Comprehensive clinical information and the distribution of antibiotic resistance genes, and serotypes may play important roles in the treatment process.

Genome-wide association study of Klebsiella pneumoniae identifies variations linked to carbapenems resistance.

Klebsiella pneumoniae (KP) is one of the microorganisms that can acquire carbapenem-resistance (CR), and few antimicrobial therapy options exist for infections caused by Carbapenem-Resistant KP (CRKP). In recent years, with the increase of carbapenem resistance rates, treating CRKP has become a serious public health threat in clinical practice. We have collected 2,035 clinical KP isolates from a tertiary hospital in China. Whole genome sequencing data coupled with their binary antimicrobial susceptibility testing data were obtained to conduct the genome-wide association study using a bayesian-based method, including single nucleotide polymorphisms (SNPs) and genes. We identified 28 and 37 potential maker genes associated with imipenem and meropenem resistance, respectively. Among which 19 of them were selected in both drugs by genome-wide association study (GWAS), 11 genes among them were simultaneously validated in independent datasets. These genes were likely related to biofilm formation, efflux pump, and DNA repairing. Moreover, we identified 13 significant CR related SNPs in imipenem or meropenem, with one SNP located in the non-coding region and validated in the independent datasets. Our study indicates complex mechanisms of carbapenems resistance and further investigation of CRKP-related factors are warranted to better understand their contributions to carbapenems resistance. These identified biomarkers may provide targets for future drug interventions or treatments.

Glyphosate and glyphosate-based herbicides (GBHs) induce phenotypic imipenem resistance in Pseudomonasaeruginosa

GBHs are the most widely used herbicides for weed control worldwide that potentially affect microorganisms, but the role of their sublethal exposure in the development of antibiotic resistance of Pseudomonasaeruginosa is still not fully investigated. Here, the effects of glyphosate acid (GLY), five glyphosate-based herbicides (GBHs), and POE(15), a formerly used co-formulant, on susceptibility to imipenem, a potent carbapenem-type antibiotic, in one clinical and four non-clinical environmental P.aeruginosa isolates were studied. Both pre-exposure in broth culture and co-exposure in solid media of the examined P.aeruginosa strains with 0.5% GBHs resulted in a decreased susceptibility to imipenem, while other carbapenems (doripenem and meropenem) retained their effectiveness. Additionally, the microdilution chequerboard method was used to examine additive/antagonistic/synergistic effects between GLY/POE(15)/GBHs and imipenem by determining the fractional inhibitory concentration (FIC) indexes. Based on the FIC index values, glyphosate acid and Total demonstrated a potent antagonistic effect in all P.aeruginosa strains. Dominator Extra 608 SL and Fozat 480 reduced the activity of imipenem in only one strain (ATCC10145), while POE(15) and three other GBHs did not have any effect on susceptibility to imipenem. Considering the simultaneous presence of GBHs and imipenem in various environmental niches, the detected interactions between these chemicals may affect microbial communities. The mechanisms of the glyphosate and GBH-induced imipenem resistance in P.aeruginosa are yet to be investigated.

424.3: Trends of Antibiotic Resistance in E. Coli, Klebsiella Spp., Pseudomonas Aeruginosa and Enterococcus Spp. Urinary Tract Infection in Renal Transplant Recipients From Pakistan Over a Decade

Introduction: Antimicrobial resistance is a major public threat worldwide. There has been an emergence of multi-drug resistant (MDR) bacterial infections over the last decade. MDR Klebsiella species have become one of the most common nosocomial pathogens in hospitals. In Pakistan, many studies reported a rising trend of resistance to antimicrobials in clinical isolates of Klebsiella species (spp.), E-coli, Pseudomonas aeruginosa and Enterococcus spp. Solid-organ transplant (SOT) recipients are more prone to infections, particularly with MDR organisms due to immunocompromised status, multiple hospital visits, and increased exposure to antibiotics. There is a paucity of data on antibiotic susceptibility patterns among renal transplant recipients from Pakistan. This study is conducted to find the trends in antimicrobial resistance patterns among common organisms isolated in the urinary tract over a 10-year period in renal transplant recipients. The aim is to guide the physicians regarding decisions over empirical antimicrobial choices. Methods: Sindh Institute of Urology and Transplantation (SIUT) is a 700-bedded tertiary care hospital in Karachi, Pakistan. It has had a comprehensive renal transplantation program with more than 6500 transplantations now. A retrospective computerized data review of urine cultures from renal transplant recipients in 2010 and 2020 was conducted. The trend of E.coli, Klebsiella species (spp.) Pseudomonas aeruginosa and Enterococcus spp. were collected. The resistance pattern of amoxicillin-clavulanic acid, ceftriaxone (ceftazidime for Pseudomonas aeurginosa), piperacillin-tazobactam, ciprofloxacin, amikacin, co-trimoxazole, and imipenem were compared over the 10 years period. Results: A total of 2,088 out of 6,249 (33%) and 2902 out of 8,115 (36%) urine cultures were positive in 2010 and 2020 respectively. The most common organisms isolated and their trend in the last decade is shown in figure 1.Over the decade, E-coli strains become 100% resistant to ciprofloxacin, ceftriaxone resistance has increased to 80%, and imipenem to 11%. In Klebsiella spp. imipenem resistance has increased to 19%. There is no significant change in the resistance pattern among Pseudomonas aeurginosa. Regarding Enterococcus spp. there is a rise in vancomycin resistance over the decade from 13% to 17% (Figure 2).Conclusion: Resistance to broad-spectrum antimicrobials has been increased with a>10% increase in carbapenems resistance over the last 10 years. E-coli has particularly become more resistant over the decade. We are also seeing more vancomycin-resistant enterococcus. The alarming increase in resistance may lead to increased morbidity in renal transplant recipients because we are left with only injectable options. We need a robust stewardship program for judicious use of antimicrobials and better infection control measures to contain increasing resistance.

Resistance evolution can disrupt antibiotic exposure protection through competitive exclusion of the protective species

Antibiotic degrading bacteria can reduce the efficacy of drug treatments by providing antibiotic exposure protection to pathogens. While this has been demonstrated at the ecological timescale, it is unclear how exposure protection might alter and be affected by pathogen antibiotic resistance evolution. Here, we utilised a two-species model cystic fibrosis (CF) community where we evolved the bacterial pathogen Pseudomonas aeruginosa in a range of imipenem concentrations in the absence or presence of Stenotrophomonas maltophilia, which can detoxify the environment by hydrolysing β-lactam antibiotics. We found that P. aeruginosa quickly evolved resistance to imipenem via parallel loss of function mutations in the oprD porin gene. While the level of resistance did not differ between mono- and co-culture treatments, the presence of S. maltophilia increased the rate of imipenem resistance evolution in the four μg/ml imipenem concentration. Unexpectedly, imipenem resistance evolution coincided with the extinction of S. maltophilia due to increased production of pyocyanin, which was cytotoxic to S. maltophilia. Together, our results show that pathogen resistance evolution can disrupt antibiotic exposure protection due to competitive exclusion of the protective species. Such eco-evolutionary feedbacks may help explain changes in the relative abundance of bacterial species within CF communities despite intrinsic resistance to anti-pseudomonal drugs.