OXA-48 Carbapenemase Research Articles

Successful Treatment of Bacteremia and Ventilator-Associated Pneumonia Caused by KPC/OXA-48-like Klebsiella pneumoniae Co-Producer with a Continuous Infusion of High-Dose Meropenem Plus Fosfomycin Guided by Real-Time Therapeutic Drug Monitoring.

Bacteremia and ventilator-associated pneumonia due to a pan-resistant Klebsiella pneumoniae strain co-producing KPC and OXA-48 carbapenemases was successfully treated in a COVID-19 critically ill patient with a combination therapy of a high-dose continuous infusion of meropenem (up to 3 g every 6 h, daily) plus fosfomycin (up to 24 g/daily) that was guided by real-time therapeutic drug monitoring. Clinical pharmacological advice was helpful in maximizing, over time, the pharmacodynamic target attainment of both antibiotics.

Diffusion of OXA-48 carbapenemase among urinary isolates of Klebsiella pneumoniae in non-hospitalized elderly patients

BackgroundRecently, a dramatic increase of Klebsiella pneumoniae positive for OXA-48 β-lactamases was observed first in the hospital setting and later in the long-term care facilities (LTCFs) and community in the Zagreb County, particularly, in urinary isolates. The aim of the study was to analyse the epidemiology and the mechanisms of antibiotic resistance of OXA-48 carbapenemase producing K. pneumoniae strains isolated from urine of non-hospitalized elderly patients.ResultsThe isolates were classified into two groups: one originated from the LTCFs and the other from the community. Extended-spectrum β-lactamases (ESBLs) were detected by double disk-synergy (DDST) and combined disk tests in 55% of the isolates (51/92). The ESBL-positive isolates exhibited resistance to expanded-spectrum cephalosporins (ESC) and in majority of cases to gentamicin. LTCFs isolates showed a significantly lower rate of additional ESBLs and consequential resistance to ESC and a lower gentamicin resistance rate compared to the community isolates, similarly to hospital isolates in Zagreb, pointing out to the possible transmission from hospitals.ESBL production was associated with group 1 of CTX-M or SHV-12 β-lactamases. Ertapenem resistance was transferable from only 12 isolates. blaOXA-48 genes were carried by IncL plasmid in 42 isolates. In addition IncFII and IncFIB were identified in 18 and 2 isolates, respectively. Two new sequence types were reported: ST4870 and ST4781.ConclusionsThis study showed eruptive and extensive diffusion of OXA-48 carbapenemase to LTCFs and community population in Zagreb County, particularly affecting patients with UTIs and urinary catheters. On the basis of susceptibility testing, β-lactamase production, conjugation experiments, MLST and plasmid characterization it can be concluded that there was horizontal gene transfer between unrelated isolates, responsible for epidemic spread of OXA-48 carbapenemase in the LTCFs and the community The rapid spread of OXA-48 producing K. pneumoniae points out to the shortcomings in the infection control measures.

Detection of NDM-1/5 and OXA-48 co-producing extensively drug-resistant hypervirulent Klebsiella pneumoniae in Northern Italy

Using a hybrid long-read sequencing approach, we aimed to fully characterise four extensively-drug resistant (XDR) hypervirulent Klebsiella pneumoniae isolates, one of which represented the first strain isolated in Italy co-expressing NDM-1/5 and OXA-48 carbapenemases. Whole-genome sequencing was performed using Illumina and Oxford Nanopore Technology platforms. An assembly pipeline was used to recover the structures both of the chromosome and plasmids. Multilocus sequence typing (MLST) showed that these strains belonged to high-risk sequence types (STs) not commonly circulating in Italy (ST383, ST147 and ST15). The hybrid sequencing approach allowed to characterise three multidrug resistance plasmids, which demonstrated high homology with previously sequenced plasmids, that were simultaneously detected in one ST383 strain carrying, respectively, blaNDM-1, blaNDM-5 and blaOXA-48. This is the first report in Italy of new hypervirulent XDR K. pneumoniae clones characterised by co-production of OXA-48, NDM-1 and NDM-5. The discovery of new high-risk clones harbouring multiple mobile elements is a growing problem that poses a great challenge for public health.

The Spread of Insertion Sequences Element and Transposons in Carbapenem Resistant Acinetobacter baumannii in a Hospital Setting in Southwestern Iran.

BackgroundAcinetobacter baumannii is one of the most important hospital pathogenic bacteria that cause infectious diseases. The present study aimed to determine the frequency of carbapenem resistance genes in association with transposable elements and molecular typing of carbapenem-resistant A. baumannii bacteria collected from patients in Shiraz, Iran.Materials and MethodsA total of 170 carbapenem-resistant A. baumannii isolates were obtained from different clinical specimens in two hospitals. The minimum inhibitory concentrations (MIC) of imipenem were determined and the prevalence of OXA Carbapenemases, Metallo-β-lactamases genes, insertion sequences (IS) elements, and transposons were evaluated by the polymerase chain reaction (PCR) method. Finally, molecular typing of the isolates was performed by the Enterobacterial Repetitive Intergenic Consensus-PCR method.ResultsThe MICs ranged from 16 to 1,024 µg/mL for imipenem-resistant A. baumannii isolates. Out of the 170 carbapenem resistant A. baumannii isolates, blaOXA-24-like (94, 55.3%) followed by blaOXA-23-like (71, 41.7%) were predominant. In addition, A. baumannii isolates carried blaVIM (71, 41.7%), blaGES (32, 18.8%), blaSPM (4, 2.3%), and blaKPC (1, 0.6%). Moreover, ISAba1 (94.2%) and Tn2009 (39.2%) were the most frequent transposable elements. Furthermore, (71, 44.0%) and (161, 94.7%) of the ISAba1 of the isolates were associated with blaOXA-23 and blaOXA-51 genes, respectively. Besides (3, 1.7%), (1, 0.6%) and (5, 2.9%) of blaOXA-23 were associated with IS18, ISAba4, and ISAba2, respectively. Considering an 80.0% cut off, clusters and four singletons were detected.ConclusionAccording to the results, transposable elements played an important role in the development of resistance genes and resistance to carbapenems. The results also indicated carbapenem-resistant A. baumannii bacteria as a public health concern.

Molecular Analysis of Oxacillinase Genes and Identification of Drug Resistance Pattern in MDR Strains of Acinetobacter baumannii Isolated from Burn Wound Samples in Kermanshah, Iran

Introduction: Carbapenem Resistant Acinetobacter Baumannii (CRAB) is a dangerous nosocomial pathogen that can cause high mortality in patients. This bacterium has a remarkable ability to acquire various resistance mechanisms due to this it is considered as one of the health priorities. Aim: To investigate the prevalence of the OXA-23, OXA-24, and OXA-58 genes in Acinetobacter baumannii isolates collected from burn wound samples in Kermanshah, Iran. Materials and Methods: A cross-sectional study was done during 11 months period from December 2018 to October 2019, 74 A. baumannii isolates were collected from those admitted to the Burns Unit of Imam Khomeini Hospital in Kermanshah, Iran. The 74 A. baumannii isolates were detected using particular bacteriological methods. Following determination of the antibiotic sensitivity of the specimens using the disk diffusion technique, polymerase chain reaction was performed to determine the frequency of the OXA-23, OXA-24, and OXA-58 genes using their specific primers. Data were analysed using Fisher’s-exact test and Chi-squared test in Statistical Package for the Social Sciences (SPSS) version 20.0. A p-value <0.05 was considered statistically significant. Results: All the 74 A. baumannii isolates were MultidrugResistant (MDR) (41 from males and 33 from females). The highest drug resistance was against cefotaxime (100%) and piperacillin (98.6%), while all the isolates were sensitive to polymyxin B and colistin. Oxacillinase genes with the highest and lowest frequencies were OXA-23 (64.7%) and OXA-58 (3.5%), respectively. The highest frequency of isolates with two genes were related to OXA-23 and OXA-24. A significant relationship was observed among the existence of oxacillinase genes and resistance to some antibiotics. Conclusion: The results of this study indicated the significance of OXA carbapenemase genes in burn patients. Due to the high drug resistance of A. baumannii isolates collected from wound samples, the identification of carbapenemase-producing A. baumannii isolates is paramount in developing prevention and control programs for these drug-resistant isolates.

Citrobacter freundii and Acinetobacter baumanii infection in a patient with neoplastic lung disease – Case report

An 85-year-old male with a tumour in his right lung was admitted to Internal Diseases Ward to continue treatment after suffering a sudden cardiac arrest. An empiric antibiotic therapy with amoxycillin was introduced due to increased inflammation markers. Blood and sputum were collected. An abundant growth of AmpC β-lactamase-producing Citrobacter freundii was observed in culture grown from the sputum. The antibiogram showed retained sensitivity to fluoroquinolones. The therapy was modified by replacing β-lactam with ciprofloxacin. Neither clinical nor laboratory improvement were observed. Blood culture indicated sepsis of Acinetobacter baumannii etiology. The strain was suspected of producing OXA carbapenemase (CARBA test positive), KPC (-), MBL (-). Antibiogram illustrated retained sensitivity to gentamicin and colistin with complete resistance to ciprofloxacin. Another modification in treatment was implemented and ciprofloxacin was replaced with colistin.

High Prevalence of OXA-23 Carbapenemase-Producing Proteus mirabilis among Amoxicillin-Clavulanate-Resistant Isolates in France.

In this multicentric study performed in 12 French hospitals, we reported that 26.9% (14/52) of the amoxicillin-clavulanate-resistant Proteus mirabilis isolates produced the OXA-23 carbapenemase. We found that an inhibition zone diameter of <11 mm around the amoxicillin-clavulanate disc was an accurate screening cutoff to detect these OXA-23 producers. We confirmed by whole-genome sequencing that these OXA-23-producers all belonged to the same lineage that has been demonstrated to disseminate OXA-23 or OXA-58 in P. mirabilis.

First Clinical Cases of OXA-48-Producing Klebsiella pneumoniae in Peru

Background: Carbapenemase-producing Enterobacteriaceae (CPE) represents a global public health concern and systemic infections associated with OXA-48 carbapenemase are increasingly being reported in Latin America. Here, we present the first 2 cases of systemic infections by OXA-48-Producing Klebsiella pneumoniae in Peru. A favorable clinical response was observed after targeted treatment with colistin as a backbone.

Impact of Phage Therapy on Multidrug-Resistant Escherichia coli Intestinal Carriage in a Murine Model.

Introduction: The growing resistance of bacteria to antibiotics is a major global public health concern. An important reservoir of this resistance is the gut microbiota. However, limited data are available on the ability of phage therapy to reduce the digestive carriage of multidrug-resistant bacteria. Materials and methods: Four novel lytic phages were isolated in vitro for efficacy against an extended-spectrum beta-lactamase-producing (ESBL) Escherichia coli strain also resistant to carbapenems through a carbapenemase OXA-48. The first step was to develop models of ESBL E. coli digestive carriage in mice. The second step was to test the efficacy of an oral and rectal phage therapy (a cocktail of four phages or microencapsulated phage) to reduce this carriage. Results: The two most intense models of digestive carriage were obtained by administering amoxicillin (0.5 g·L−1) continuously in the drinking water (Model 1) or pantoprazole (0.1 g·L−1) continuously in the drinking water, combined with amoxicillin (0.5 g·L−1), for the first 8 days (Model 2). Oral administration of the phage cocktail to Model 1 resulted in a transient reduction in the concentration of ESBL E. coli in the faeces 9 days after the bacterial challenge (median = 5.33 × 108 versus 2.76 × 109 CFU·g−1, p = 0.02). In contrast, in Model 2, oral or oral + rectal administration of this cocktail did not alter the bacterial titre compared to the control (area under the curve, AUC, 3.49 × 109; 3.41 × 109 and 3.82 × 109 for the control, oral and oral + rectal groups, respectively; p-value > 0.8 for each two-by-two group comparison), as well as the administration of an oral microencapsulated phage in Model 1 (AUC = 8.93 × 109 versus 9.04 × 109, p = 0.81). Conclusions: Oral treatment with amoxicillin promoted digestive carriage in mice, which was also the case for the addition of pantoprazole. However, our study confirms the difficulty of achieving efficacy with phage therapy to reduce multidrug-resistant bacterial digestive carriage in vivo.

1251. Comparative Evaluation of Phenotypic Synergy Tests vs. Resist-4 O.K.N.V® and NG Test Carba 5® Lateral Flow Immunoassays for the Detection and Differentiation of Carbapenemases in Enterobacterales and Pseudomonas aeruginosa

BackgroundThe spread of carbapenem resistant Pseudomonas aeruginosa and carbapenemase-producing Enterobacterales (CPE) has had a great impact on morbidity and mortality. COVID-19 pandemic has favoured the selection of these microorganisms because of the excessive and prolonged use of broad-spectrum antibiotics and the outbreaks related to patient transfer between hospitals and inadequate use of personal protective equipment. Therefore, detection is considered essential for their control. Our aim was to compare conventional phenotypic synergy tests and two lateral flow immunoassays for detecting carbapenemases in Enterobacterales and P. aeruginosa.MethodsWe analysed 100 carbapenem-resistant Gram-negative bacilli isolates, 80 Enterobacterales and 20 Pseudomonas aeruginosa, (86 isolates producing KPC, NDM, OXA-48, IMP and VIM carbapenemases and 14 non-carbapenemase-producing isolates). We performed a modified Hodge test, boronic acid and ethylenediaminetetraacetic acid (EDTA) synergy tests, and two lateral flow immunoassays: RESIST-4 O.K.N.V (Coris Bioconcept®) and NG Test Carba 5® (NG Biotech®).ResultsIn total, 76 KPC, 7 VIM, 1 NDM, 1 OXA-48 and 1 isolate coproducing KPC + NDM enzymes were included. The concordance of different methods estimated by Kappa index was 0.432 (Standard error: 0.117), thus showing a high variability with the synergy tests with boronic acid and EDTA and reporting 16 false negatives that were detected by the two immunochromatographic methods. Co-production was only detected using immunoassays. Figure 1. Errors in synergy tests. 1) KPC-producing K. pneumoniae not detected with boronic acid and EDTA (1a). Positive result adjusting distance to 5 mm (1b) and positive result by NG Test Carba 5® and RESIST-4 O.K.N.V® immunoassays (1c). 2) VIM -producing P. aeruginosa with inconclusive EDTA result (2a), Positive result adjusting distance to 5 mm (2b), confirmation of VIM by immunoassay (2c). 3) K. pneumoniae with KPC and NDM co-production without synergistic effect with boronic acid or EDTA (3a), positivity for both enzymes by immunoassay (3b). 4) Impact of distance between disks: False negative for serine-carbapenemases with 15 mm (4a) positive result at 10 mm (4b). Differences in boronic acid tests for serin-carbapenemases at 10 mm, 5 mm and 0 mm distance (4c, 4d). Differences in synergy between imipenem, meropenem and ertapenem discs at 0 mm distance (4e).Table 2. Results of synergy methods and immunoassay tests for Enterobacterales and Pseudomonas aeruginosa MHTModified Hodge Test, APB: boronic acid synergy; EDTA: EDTA synergy; Pos: positive; Neg: negative. KPC (Klebsiella pneumoniae Carbapenemase), VIM (Verona integron-mediated metallo- β-lactamase), NDM (New Delhi metallo-β-lactamase), OXA (oxacillinase-48-like carbapenemase (OXA-48))ConclusionConventional phenotypic synergy tests with boronic acid and EDTA used for detecting carbapenemases are suboptimal and their routine use should be reconsidered. They depend on the degree of enzyme expression and the distance between disks. Lateral flow immunoassay tests are a rapid and cost-effective tool to detect and differentiate carbapenemases, improving clinical outcomes through targeted therapy and promoting infection prevention measures. Disclosures Diego Josa, Msc, ALIFAX (Speaker’s Bureau) German Esparza, n/a, Biomerieux (Consultant)Pfizer (Speaker’s Bureau) Luis Reyes, n/a, MSD (Speaker’s Bureau)

Carbapenem-Resistant Citrobacter spp. as an Emerging Concern in the Hospital-Setting: Results From a Genome-Based Regional Surveillance Study.

The rise of Carbapenem-resistant Enterobacterales (CRE) represents an increasing threat to patient safety and healthcare systems worldwide. Citrobacter spp., long considered not to be a classical nosocomial pathogen, in contrast to Klebsiella pneumoniae and Escherichia coli, is fast gaining importance as a clinical multidrug-resistant pathogen. We analyzed the genomes of 512 isolates of 21 CRE species obtained from 61 hospitals within a three-year-period and found that Citrobacter spp. (C. freundii, C. portucalensis, C. europaeus, C. koseri and C. braakii) were increasingly detected (n=56) within the study period. The carbapenemase-groups detected in Citrobacter spp. were KPC, OXA-48/-like and MBL (VIM, NDM) accounting for 42%, 31% and 27% respectively, which is comparable to those of K. pneumoniae in the same study. They accounted for 10%, 17% and 14% of all carbapenemase-producing CRE detected in 2017, 2018 and 2019, respectively. The carbapenemase genes were almost exclusively located on plasmids. The high genomic diversity of C. freundii is represented by 22 ST-types. KPC-2 was the predominantly detected carbapenemase (n=19) and was located in 95% of cases on a highly-conserved multiple-drug-resistance-gene-carrying pMLST15 IncN plasmid. KPC-3 was rarely detected and was confined to a clonal outbreak of C. freundii ST18. OXA-48 carbapenemases were located on plasmids of the IncL/M (pOXA-48) type. About 50% of VIM-1 was located on different IncN plasmids (pMLST7, pMLST5). These results underline the increasing importance of the Citrobacter species as emerging carriers of carbapenemases and therefore as potential disseminators of Carbapenem- and multidrug-resistance in the hospital setting.

Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii Isolated from the Intensive Care Unit in a Tertiary Teaching Hospital in Malaysia.

The emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) has now become a global sentinel event. CRAB infections often instigate severe clinical complications and are potentially fatal, especially for debilitated patients. The present study aimed to conduct molecular characterization on CRAB isolated from patients in the intensive care unit from 2015 to 2016 and determine the risk factors associated with patients’ mortality. One hundred CRAB isolates were retrospectively selected and included in this study. Antimicrobial susceptibility testing showed that all isolates remained susceptible to colistin, even though 62% of them conferred resistance to all other classes of antibiotics tested. OXA carbapenemase gene was found to be the predominant carbapenemase gene, with 99% of the isolates coharbouring blaOXA-23-like and blaOXA-51-like carbapenemase genes. All isolates were carrying intact CarO genes, with the presence of various degree of nucleotide insertion, deletion and substitution. Overall, PFGE subtyped the isolates into 13 distinct pulsotypes, with the presence of 2 predominant pulsotypes. Univariate analysis implied that age, infection/colonization by CRAB, ethnicity, comorbidity and CRAB specimen source were significantly associated with in-hospital mortality. Multivariate analysis identified a higher risk of mortality for patients who are of Chinese ethnicity with diabetes as an underlying disease. As CRAB infection could lead to high rate of mortality, comprehensive infection control measures are needed to minimize the spread of this pathogen.

Clinical Efficacy of Ceftazidime-Avibactam in the Treatment of Infections Caused by Carbapenem–Resistant Gram-Negative Bacteria

The wide spread of carbapenemases among gram-negative bacteria of the Enterobacterales order in hospitals around the world, including Russia, creates great difficulties in the effective use of antibiotics for these infections in the ICU. Ceftazidime-avibactam is the first antibiotic developed and studied for the treatment of infections caused by carbapenem-resistant enterobacteria. Ceftazidime-avibactam shows high activity against producers of class A and D serine carbapenemases (KPC and OXA-48). In combination with aztreonam it is effective in infections caused by producers of class B metallo-beta-lactamases (NDM and VIM). The review analyzes the results of 19 non-comparative and 10 comparative studies of ceftazidime-avibactam in infections caused by carbapenem-resistant Enterobacterales, as well as case reports. According to the data of non- comparative studies, the clinical efficacy of ceftazidime-avibactam ranged from 45.0 to 87.2%, on average 71.7±11.3%, and the eradication rate of KPC or OXA-48 carbapenemase producers ranged from 40.0 to 100%, on average 65.5±18.6%. The effectiveness of ceftazidime-avibactam in comparative studies was 67.9±17.3%, which was significantly higher compared to other antibiotics (44.3±14.4%,P=0.012). Treatment with ceftazidime-avibactam was accompanied by a significantly lower 30-day mortality in contrast to other antibiotics – 23.8±13.5% and 41.0±13.6%, respectively,P=0.001. The development of resistance in Enterobacterales species to ceftazidime-avibactam during therapy is rarely observed, on average 5.4±4.4%, which characterizes a rather low potential of the antibiotic in resistance selection. Early administration of ceftazidime-avibactam is accompanied by better treatment results as opposed to delayed therapy. Treatment of infections caused by carbapenem-resistant enterobacteria with ceftazidime-avibactam is associated with a significantly higher recovery rate and a lower mortality compared to other regimens of antibacterial therapy.

Comparison of Chromogenic Culture Media, Rapid Immunochromatographic Test and Temocillin Resistance for The Detection of OXA-48 Carbapenemase-Positive Klebsiella Pneumonia Strains

Objectives: The study was aimed to compare the performance of three different approaches (temocillin disc diffusion test (TDD), immunochromatographic assay, OXA-48 K-SET, and chromogenic assay containing ChromID OXA-48 media) with PCR in a collection of K. pneumoniae producing OXA-48. Materials and methods: A total of 45 carbapenem resistant K. pneumoniae isolates (27 were OXA-48 positive) were included in the study. Polymerase chain reaction (PCR), TDD, OXA-48 K-SET, ChromID OXA-48 media were applied to all isolates. Results: The OXA-48 K-SET was found to be 100% compatible with gold standard PCR for the identification of OXA-48 positive Klebsiella pneumoniae strains. 100% sensitivity and 88.8% specificity were found with the ChromID OXA-48 medium method. Sensitivity and specificity of the TDD assay were found 100% and 77.8%, respectively. Conclusion: The OXA-48 K-Set had excellent performance for detecting OXA-48 carbapenemase and can be used easily and reliably in the routine clinical microbiology laboratory for rapid detection of OXA-48 producing K. pneumoniae isolates, particularly in endemic regions. ChromID media and temocillin disc diffusion testing can be applied in laboratories as part of the identification and screening of carbapenemase-positive Klebsiella pneumoniae.

High occurrence of carbapenem-resistant Escherichia coli isolates from healthy rabbits (Oryctolagus cuniculus): first report of blaIMI and blaVIM type genes from livestock in Tunisia.

We aimed to study the antibiotic susceptibility and possible occurrence of extended-spectrum beta-lactamases (ESBL)/carbapenemase-producing Escherichia coli isolates collected from rabbits in Tunisia. In all, 35 faecal samples from healthy rabbits were collected from one farm and E.coli were isolated from three media: antibiotic-free TBX agar, TBX+2 mg l-1 cefotaxime and TBX+1 mg l-1 imipenem. In total, 39 E.coli isolates were recovered; the majority showed resistance to at least one antibiotic and none was ESBL producer. Carbapenem resistance was detected in 16 isolates from either selective or un-selective media. Phenotypic methods used to detect carbapenemase production showed two positive isolates by Modified Hodge Test, six metallo-carbapenemase producers (Imipenem disc+EDTA) and all were temocillin resistant (possible OXA-48 carbapenemase). blaVIM and blaIMP type genes were detected in two and one isolates, respectively; one of them harboured both genes. Isolates contained common genes encoding resistance to sulphonamides (sul1, sul2), tetracycline (tetA, tetB, tetC) and fluoroquinolones (qnrS, aac(6')-Ib-cr). Class 1 and 2 integrons were detected in five and four isolates, respectively. These findings highlight the importance of rabbit production as reservoir of carbapenem-resistant E.coli and argument the first report of blaVIM and blaIMP genes in livestock in Tunisia.

In silico study and biological screening of benzoquinazolines as potential antimicrobial agents against methicillin-resistant Staphylococcus aureus, carbapenem-resistant Klebsiella pneumoniae, and fluconazole-resistant Candida albicans

Globally, antibiotic-resistant pathogens have become a serious threat to public health. The use of drugs having structures different from those applied in the clinical treatments of bacterial infections is a well-known potential solution to the antibiotic resistance crisis. Benzo-[g]-quinazolines were identified by our research group as a new class of antimicrobial agents. Herein, to follow-up the research on such compounds, three benzo-[g]-quinazolines (1–3) were studied, as in vitro antibacterial candidates against methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Klebsiella pneumoniae, and fluconazole-resistant Candida albicans, as well. The minimum inhibitory concentration (MIC) assay for benzoquinazolines was carried out via the calorimetric broth microdilution method using the XTT assay in comparison with vancomycin, ciprofloxacin, and ketoconazole as reference drugs. The target compounds 1–3 revealed high variation in their activity against the examined resistant microbial strains. Benzoquinazoline 3 exhibited a more potent effect against the resistant strains compared with the reference drugs. A docking study was performed to identify the interactions between the benzoquinazolines 1–3 and ligand proteins (OXA-48 carbapenemase, β-lactamase, and sterol 14-alpha demethylase (CYP51)) at the active sites. Benzoquinazolines 1–3 showed very weak cytotoxicity against human lung fibroblast normal cells (WI-38). The targets showed promising antimicrobial effects against the three resistant strains. These findings may inform future inhibitor discoveries targeting penicillin-binding proteins.

Meropenem Versus Piperacillin-Tazobactam for Definitive Treatment of Bloodstream Infections Caused by AmpC β-Lactamase-Producing Enterobacter spp, Citrobacter freundii, Morganella morganii, Providencia spp, or Serratia marcescens: A Pilot Multicenter Randomized Controlled Trial (MERINO-2).

BackgroundCarbapenems are recommended treatment for serious infections caused by AmpC-producing gram-negative bacteria but can select for carbapenem resistance. Piperacillin-tazobactam may be a suitable alternative.MethodsWe enrolled adult patients with bloodstream infection due to chromosomal AmpC producers in a multicenter randomized controlled trial. Patients were assigned 1:1 to receive piperacillin-tazobactam 4.5 g every 6 hours or meropenem 1 g every 8 hours. The primary efficacy outcome was a composite of death, clinical failure, microbiological failure, and microbiological relapse at 30 days.ResultsSeventy-two patients underwent randomization and were included in the primary analysis population. Eleven of 38 patients (29%) randomized to piperacillin-tazobactam met the primary outcome compared with 7 of 34 patients (21%) in the meropenem group (risk difference, 8% [95% confidence interval {CI}, –12% to 28%]). Effects were consistent in an analysis of the per-protocol population. Within the subcomponents of the primary outcome, 5 of 38 (13%) experienced microbiological failure in the piperacillin-tazobactam group compared to 0 of 34 patients (0%) in the meropenem group (risk difference, 13% [95% CI, 2% to 24%]). In contrast, 0% vs 9% of microbiological relapses were seen in the piperacillin-tazobactam and meropenem arms, respectively. Susceptibility to piperacillin-tazobactam and meropenem using broth microdilution was found in 96.5% and 100% of isolates, respectively. The most common AmpC β-lactamase genes identified were blaCMY-2, blaDHA-17, blaCMH-3, and blaACT-17. No ESBL, OXA, or other carbapenemase genes were identified.ConclusionsAmong patients with bloodstream infection due to AmpC producers, piperacillin-tazobactam may lead to more microbiological failures, although fewer microbiological relapses were seen.Clinical Trials RegistrationNCT02437045.

Carbapenem and colistin-resistant bacteria in North Lebanon: Coexistence of mcr-1 and NDM-4 genes in Escherichia coli.

The increasing incidence of infections caused by multidrug-resistant bacteria is considered a global health problem. This study aimed to investigate this resistance in Gram-negative bacteria isolated from patients hospitalized in North-Lebanon. All isolates were identified using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antibiotic susceptibility testing was achieved using disk diffusion, E-test and Broth microdilution methods. Phenotypic detection of carbapenemase was carried out using the CarbaNP test. RT-PCR, standard-PCR and sequencing were performed to detect resistance genes and oprD gene. Conjugal transfer was carried out between our isolates and Escherichia coli J53 to detect the genetic localization of resistance genes. MLST was conducted to determine the genotype of each isolate. Twenty-three carbapenem-resistant Enterobacterales of which eight colistin-resistant Escherichia coli, and Twenty carbapenem-resistant Pseudomonas aeruginosa were isolated. All isolates showed an imipenem MIC greater than 32 mg/mL with MICs for colistin greater than 2 mg/L for E. coli isolates. All the Enterobacterales isolates had at least one carbapenemase-encoding gene, with E. coli isolates coharboring blaNDM-4 and mcr-1 genes. Moreover, 16/20 Pseudomonas aeruginosa harbored the blaVIM-2 gene and 18/20 had mutations in the oprD gene. MLST revealed that the isolates belonged to several clones. We report here the first description in the world of clinical E. coli isolates coharboring blaNDM-4 and mcr-1 genes, and K. pneumoniae isolates producing NDM-6 and OXA-48 carbapenemases. Also, we describe the emergence of NDM-1-producing E. cloacae in Lebanon. Screening for these isolates is necessary to limit the spread of resistant microorganisms in hospitals.

Ceftazidime - Avibactam susceptibility among carbapenem-resistant Enterobacterales in a pilot study in Turkey.

This study aimed to detect carbapenemase genes and to determine the in vitro susceptibility of Ceftazidime-Avibactam (CZA) in Enterobacterales isolates. Carbapenemase genes were detected by polymerase chain reaction. CZA sensitivity of isolates was evaluated with broth microdilution (BMD) and disk diffusion methods. A total of 318 carbapenem-resistant Enterobacterales isolates were included. Most of the isolates (n = 290, 91.2%) were identified as Klebsiella pneumoniae. The most common carbapenemase type was OXA-48 (n = 82, 27.6%). CZA susceptibility was evaluated in 84 isolates with OXA-48 and KPC carbapenemase activity. Both BMD and disk diffusion methods revealed that 95.2% of the isolates were sensitive to CZA; whereas, 4 (4.76%) isolates were resistant to CZA. Among colistin resistant isolates, 96.5% (n = 80) of them were susceptible to CZA. Our study demonstrated high in vitro efficacy of CZA in Enterobacterales isolates producing OXA-48 carbapenemase. High susceptibility rates against colistin resistant isolates which generally are also pan drug resistant, makes CZA a promising therapeutic choice for difficult-to-treat infections. Due to its high correlation with the BMD, disk diffusion method is a suitable and more practical method in detecting CZA in vitro activity.

Absence of transmission of NDM and OXA-48 carbapenemase genes in a chronic care unit of a long-term care facility.

Infection prevention and control measures are used to contain outbreaks of carbapenemase-producing Enterobacteriaceae. We report the absence of transmission of Klebsiella pneumoniae carrying New Delhi metallo-β-lactamase and oxacillinase-48 genes among 19 screened contacts of an index case after 14 months of routine practices in a long-term care facility.