Antimicrobial resistance and prevalence of extended-spectrum beta-lactamase-producing Klebsiella species in East Tennessee dairy farms.

Klebsiella species commonly reside in dairy cattle guts and are consistently exposed to beta-lactam antibiotics, including ceftiofur, which are frequently used on the U.S. dairy farms. This may impose selection pressure and result in the emergence of extended-spectrum beta-lactamase (ESBL)-producing strains. However, information on the status and antimicrobial resistance (AMR) profile of ESBL-Klebsiella spp. in the U.S. dairy farms is largely unknown. This study aimed to determine the prevalence and AMR profile of ESBL-Klebsiella spp. and the factors affecting their occurrence in dairy cattle farms. Rectal fecal samples (n = 508) and manure, feed, and water samples (n = 64) were collected from 14 dairy farms in Tennessee. Samples were directly plated on CHROMagar ESBL, and presumptive Klebsiella spp. were confirmed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Antimicrobial susceptibility testing was performed on the isolates against panels of 14 antimicrobial agents from 10 classes using minimum inhibitory concentration. Of 572 samples, 57 (10%) were positive for ESBL-Klebsiella spp. The fecal prevalence of ESBL-Klebsiella spp. was 7.2% (95% CI: 6.5-8.0). The herd-level fecal prevalence of ESBL-Klebsiella spp. was 35.7% (95% CI: 12.7-64.8). The fecal prevalence of ESBL-Klebsiella spp. was significantly higher in calves than in cows and higher in cows with higher parity (≥3) as compared to cows with low parity (P < 0.001). Most (96.5%, n = 57) ESBL-Klebsiella spp. were resistant to ceftriaxone. The highest level of acquired co-resistance to ceftriaxone in ESBL-Klebsiella spp. was to sulfisoxazole (66.7%; 38/57). About 19% of ESBL-Klebsiella spp. were multidrug resistant. The presence of ESBL-producing Klebsiella spp. in dairy cattle, feed, and water obtained from troughs could play a crucial epidemiological role in maintaining and spreading the bacteria on farms and serving as a point source of transmission. IMPORTANCE: We collected 572 samples from dairy farms, including rectal feces, manure, feed, and water. We isolated and identified extended-spectrum beta-lactamase (ESBL)-Klebsiella spp. and conducted an antimicrobial susceptibility test and analyzed different variables that may be associated with ESBL-Klebsiella spp. in dairy farms. The results of our study shed light on how ESBL-Klebsiella spp. are maintained through fecal-oral routes in dairy farms and possibly exit from the farm into the environment. We determine the prevalence of ESBL-Klebsiella spp. and their antimicrobial susceptibility profiles, underscoring their potential as a vehicle for multiple resistance gene dissemination within dairy farm settings. We also collected data on variables affecting their occurrence and spread in dairy farms. These findings have significant implications in determining sources of community-acquired ESBL-Enterobacteriaceae infections and designing appropriate control measures to prevent their spread from food animal production systems to humans, animals, and environments.

Comparison of antimicrobial resistant Enterobacterales isolates from the dairy production environment in low and high zinc containing regions.

Heavy metals occur naturally in the environment, and their concentration varies in soil across different regions. However, the presence of heavy metals may influence the antimicrobial resistance (AMR) in bacterial populations. Therefore, the objective of this study was to investigate and characterise the antimicrobial resistance profiles of Enterobacterales in soil and bovine milk filters from high and low zinc-containing regions in Ireland. In total, 50 soil samples and 29 milk filters were collected from two geographic locations with varying soil zinc concentrations. Samples were cultured for the enumeration and detection of Enterobacterales. Specifically, extended-spectrum beta-lactamase-producing Enterobacterales, carbapenem-resistant Enterobacterales and ciprofloxacin-resistant Enterobacterales were isolated using selective media. Species identification was performed using MALDI-TOF. The phenotypic resistance profiles of selected Enterobacterales were determined by disk diffusion testing, following EUCAST and CLSI criteria; while, the genotypic resistance profiles of the same isolates were determined by whole genome sequencing (WGS). Heavy metal concentrations were also measured for all soil samples. A total of 40 antimicrobial resistant Enterobacterales were identified in soil (n = 31) and milk filters (n = 9). The predominant species detected in the high zinc-containing region was Escherichia coli in both sample types (soil n = 10, milk filters n = 2), while in the low zinc-containing region Serratia fonticola was predominant in soil samples (n = 8) and E. coli in milk filters (n = 4). Ten E. coli isolates identified from soil samples in the high zinc-containing region were multidrug resistant, showing resistance to all the antimicrobials tested, except for carbapenems. The WGS findings confirmed the phenotypic resistance results. Moreover, zinc resistance-associated genes and genes encoding for efflux pumps were identified. The current study revealed distinct phenotypic resistance profiles of Enterobacterales in low and high zinc-containing regions, and highlighted the benefit of utilising milk filters for AMR surveillance in dairy production.

Prevotella bivia Infection of a Horse Bite Wound.

Horse bites are common non-fatal injuries in the United States. Infections of horse bite wounds in humans are usually due to bacteria that correspond to the oropharyngeal bacterial flora of horses. We report the novel case of a 25-year-old woman who sustained a horse bite wound that was infected with Prevotella bivia, a Gram-negative, non-pigmented anaerobe. We discuss the epidemiology, bacteriology, and clinical management of horse bites.

Genome characterization of a multi-drug resistant Escherichia coli strain, L1PEag1, isolated from commercial cape gooseberry fruits (Physalis peruviana L.).

Introduction: Foodborne infections, which are frequently linked to bacterial contamination, are a serious concern to public health on a global scale. Whether agricultural farming practices help spread genes linked to antibiotic resistance in bacteria associated with humans or animals is a controversial question. Methods: This study applied a long-read Oxford Nanopore MinION-based sequencing to obtain the complete genome sequence of a multi-drug resistant Escherichia coli strain (L1PEag1), isolated from commercial cape gooseberry fruits (Physalis peruviana L.) in Ecuador. Using different genome analysis tools, the serotype, Multi Locus Sequence Typing (MLST), virulence genes, and antimicrobial resistance (AMR) genes of the L1PEag1 isolate were determined. Additionally, in vitro assays were performed to demonstrate functional genes. Results: The complete genome sequence of the L1PEag1 isolate was assembled into a circular chromosome of 4825.722 Kbp and one plasmid of 3.561 Kbp. The L1PEag1 isolate belongs to the B2 phylogroup, sequence type ST1170, and O1:H4 serotype based on in silico genome analysis. The genome contains 4,473 genes, 88 tRNA, 8 5S rRNA, 7 16S rRNA, and 7 23S rRNA. The average GC content is 50.58%. The specific annotation consisted of 4,439 and 3,723 genes annotated with KEEG and COG respectively, 3 intact prophage regions, 23 genomic islands (GIs), and 4 insertion sequences (ISs) of the ISAs1 and IS630 families. The L1PEag1 isolate carries 25 virulence genes, and 4 perfect and 51 strict antibiotic resistant gene (ARG) regions based on VirulenceFinder and RGI annotation. Besides, the in vitro antibiotic profile indicated resistance to kanamycin (K30), azithromycin (AZM15), clindamycin (DA2), novobiocin (NV30), amikacin (AMK30), and other antibiotics. The L1PEag1 isolate was predicted as a human pathogen, matching 464 protein families (0.934 likelihood). Conclusion: Our work emphasizes the necessity of monitoring environmental antibiotic resistance, particularly in commercial settings to contribute to develop early mitigation techniques for dealing with resistance diffusion.

When does antimicrobial resistance increase bacterial fitness? Effects of dosing, social interactions, and frequency dependence on the benefits of AmpC ß-lactamases in broth, biofilms, and a gut infection model.

One of the longstanding puzzles of antimicrobial resistance is why the frequency of resistance persists at intermediate levels. Theoretical explanations for the lack of fixation of resistance include cryptic costs of resistance or negative frequency-dependence but are seldom explored experimentally. ß-lactamases, which detoxify penicillin-related antibiotics, have well-characterized frequency-dependent dynamics driven by cheating and cooperation. However, bacterial physiology determines whether ß-lactamases are cooperative, and we know little about the sociality or fitness of ß-lactamase producers in infections. Moreover, media-based experiments constrain how we measure fitness and ignore important parameters such as infectivity and transmission among hosts. Here, we investigated the fitness effects of broad-spectrum AmpC ß-lactamases in Enterobacter cloacae in broth, biofilms, and gut infections in a model insect. We quantified frequency- and dose-dependent fitness using cefotaxime, a third-generation cephalosporin. We predicted that infection dynamics would be similar to those observed in biofilms, with social protection extending over a wide dose range. We found evidence for the sociality of ß-lactamases in all contexts with negative frequency-dependent selection, ensuring the persistence of wild-type bacteria, although cooperation was less prevalent in biofilms, contrary to predictions. While competitive fitness in gut infections and broth had similar dynamics, incorporating infectivity into measurements of fitness in infections significantly affected conclusions. Resistant bacteria had reduced infectivity, which limited the fitness benefits of resistance to infections challenged with low antibiotic doses and low initial frequencies of resistance. The fitness of resistant bacteria in more physiologically tolerant states (in biofilms, in infections) could be constrained by the presence of wild-type bacteria, high antibiotic doses, and limited availability of ß-lactamases. One conclusion is that increased tolerance of ß-lactams does not necessarily increase selection pressure for resistance. Overall, both cryptic fitness costs and frequency dependence curtailed the fitness benefits of resistance in this study.

Comparing the activity of broad-spectrum beta-lactams in combination with aminoglycosides against VIM-producing Enterobacteriaceae.

Metallo-beta-lactamase (MBL)-producing carbapenem-resistant Enterobacteriaceae (CRE) infections continue to pose a serious threat to healthcare. Due to their unique active site, MBLs evade the activity of many novel beta-lactam/beta-lactamase inhibitor combinations, which have been specifically targeted toward those carbapenemases with serine active sites. Furthermore, resistance to most, if not all, other clinically relevant antimicrobial classes leaves few reliable therapeutic options. Combination therapy has thus played a vital role in the treatment of MBL-producing CRE infections. In this study, we utilized the static time-kill assay to investigate clinically relevant concentrations of cefepime, piperacillin-tazobactam, and meropenem alone and in combination with either amikacin or the novel plazomicin to determine if combinations of routinely used beta-lactam therapy with an aminoglycoside would achieve bactericidal activity against eight clinically isolated Verona integron-encoded MBL (VIM)-producing CRE. Furthermore, we compared this activity to the combination of aztreonam/avibactam, which has shown potent activity against MBL-producing CRE. Both aztreonam/avibactam and meropenem with either aminoglycoside were rapidly bactericidal within 4 hours and remained bactericidal through 24 hours against all isolates with few exceptions. Combinations including cefepime and piperacillin-tazobactam were also rapidly bactericidal, but activity after 24 hours was inconsistent depending upon the partner aminoglycoside and isolate. Further investigation is warranted to elucidate optimal antibiotic exposures against MBL-producing CRE, including novel agents in the pipeline.IMPORTANCECarbapenem-resistant Enterobacterales (CRE) are one of the most pressing antimicrobial-resistant threats at present. In addition to exhibiting resistance to many, if not all, commonly used antimicrobial agents, CRE achieves these resistant phenotypes through a variety of mechanisms, each of which can uniquely affect available treatment options. The present study is an in vitro investigation of several Verona integron-encoded metallo-beta-lactamase (VIM)-producing CRE isolated from patients at our academic medical center. Because metallo-beta-lactamases (MBLs) are inherently resistant to many of the novel treatments designed to treat CRE due to their different active site composition, we tested several antimicrobial combinations containing routinely utilized broad-spectrum beta-lactams and aminoglycosides. Our results further our understanding of combination therapy options against VIM-producing CRE, including with non-carbapenem-beta-lactams cefepime and piperacillin. By optimizing combinations of existing antimicrobial agents, we hope to expand the available armamentarium against these resistant pathogens.

Clinical emergence of a novel extended-spectrum variant deriving from the OXY-1 ß-lactamase.

The genomic comparison of two Klebsiella michiganensis clinical isolates recovered from the same patient, one resistant to piperacillin-tazobactam and intermediate to cefotaxime, the other resistant to ceftazidime but susceptible to piperacillin-tazobactam, revealed one mutation in the blaOXY-1-24 gene accounting for a L169M substitution in the Ω loop. Cloning experiment in Escherichia coli demonstrated the contribution of this mutation to the hydrolysis spectrum extension towards ceftazidime and cefepime, whereas the resistance to piperacillin-tazobactam was reduced. To the best of our knowledge, this study shows for the first time that ceftazidime resistance can occur in vivo from OXY-1 precursor by structural alteration.

Global Dynamics of Gastrointestinal Colonisations and Antimicrobial Resistance: Insights from International Travellers to Low- and Middle-Income Countries.

Gastrointestinal microorganism resistance and dissemination are increasing, partly due to international travel. This study investigated gastrointestinal colonisations and the acquisition of antimicrobial resistance (AMR) genes among international travellers moving between Spain and low- and middle-income countries (Peru and Ethiopia). We analysed 102 stool samples from 51 volunteers collected before and after travel, revealing significantly higher rates of colonisation by both bacteria and protists upon return. Diarrhoeagenic strains of E. coli were the most notable microorganism detected using RT-PCR with the Seegene Allplex™ Gastrointestinal Panel Assays. A striking prevalence of ß-lactamase resistance genes, particularly the TEM gene, was observed both before and after travel. No significant differences in AMR genes were found between the different locations. These findings highlight the need for rigorous surveillance and preventive strategies, as travel does not significantly impact AMR gene acquisition but does affect microbial colonisations. This study provides valuable insights into the intersection of gastrointestinal microorganism acquisition and AMR in international travellers, underscoring the need for targeted interventions and increased awareness.

Characterization of antimicrobial resistant Enterobacterales isolated from spinach and soil following zinc amendment.

Antimicrobial resistant bacteria can occur in the primary food production environment. The emergence and dissemination of antimicrobial resistance (AMR) in the environment can be influenced by several factors, including the presence of heavy metals. The aim of this study was to examine the presence and characteristics of antimicrobial resistant Enterobacterales in soils and spinach grown in soils with and without zinc amendment. A total of 160 samples (92 soil and 68 spinach) were collected from two locations, in which some plots had been amended with zinc. Samples were cultured on selective agars for detection of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL), carbapenem-resistant Enterobacterales and ciprofloxacin-resistant Enterobacterales. Samples were also cultured for enumeration of total Enterobacterales. Isolates were identified by MALDI-TOF. Antimicrobial susceptibility testing was carried out in accordance with EUCAST and CLSI criteria. The whole genome sequence (WGS) of selected isolates was determined. Inductively coupled plasma atomic emission spectrometry was also performed on soil samples in order to measure the concentration of zinc. In total 20 antimicrobial resistant Enterobacterales were isolated from the soil (n = 8) and spinach samples (n = 12). In both sample types, Serratia fonticola (n = 16) was the dominant species, followed by Escherichia coli (n = 1), Citrobacter freundii (n = 1) and Morganella morganii (n = 1) detected in spinach samples, and Enterobacter cloacae (n = 1) detected in a soil sample. The WGS identified genes conferring resistance to different antimicrobials in agreement with the phenotypic results; 14 S. fonticola isolates were confirmed as ESBL producers and harboured the blaFONA gene. Genes that encoded for zinc resistance and multidrug efflux pumps, transporters that can target both antimicrobials and heavy metals, were also identified. Overall, the findings of this study suggest the presence of zinc did not influence the AMR Enterobacterales in soil or spinach samples.

Resistance and Co-Resistance of Metallo-Beta-Lactamase Genes in Diarrheal and Urinary-Tract Pathogens in Bangladesh.

Carbapenems are the antibiotics of choice for treating multidrug-resistant bacterial infections. Metallo-ß-lactamases (MBLs) are carbapenemases capable of hydrolyzing nearly all therapeutically available beta-lactam antibiotics. Consequently, this research assessed the distribution of two MBL genes and three ß-lactamases and their associated phenotypic resistance in diarrheal and urinary-tract infections (UTIs) to guide future policies. Samples were collected through a cross-sectional study, and ß-lactamase genes were detected via PCR. A total of 228 diarrheal bacteria were isolated from 240 samples. The most predominant pathogens were Escherichia coli (32%) and Klebsiella spp. (7%). Phenotypic resistance to amoxicillin-clavulanic acid, aztreonam, cefuroxime, cefixime, cefepime, imipenem, meropenem, gentamicin, netilmicin, and amikacin was 50.4%, 65.6%, 66.8%, 80.5%, 54.4%, 41.6%, 25.7%, 41.2%, 37.2%, and 42.9%, respectively. A total of 142 UTI pathogens were identified from 150 urine samples. Klebsiella spp. (39%) and Escherichia coli (24%) were the major pathogens isolated. Phenotypic resistance to amoxicillin-clavulanic acid, aztreonam, cefuroxime, cefixime, cefepime, imipenem, meropenem, gentamicin, netilmicin, and amikacin was 93.7%, 75.0%, 91.5%, 93.7%, 88.0%, 72.5%, 13.6%, 44.4%, 71.1%, and 43%, respectively. Twenty-four diarrheal isolates carried blaNDM-1 or blaVIM genes. The overall MBL gene prevalence was 10.5%. Thirty-six UTI pathogens carried either blaNDM-1 or blaVIM genes (25.4%). Seven isolates carried both blaNDM-1 and blaVIM genes. MBL genes were strongly associated with phenotypic carbapenem and other ß-lactam antibiotic resistance. blaOXA imparted significantly higher phenotypic resistance to ß-lactam antibiotics. Active surveillance and stewardship programs are urgently needed to reduce carbapenem resistance in Bangladesh.

Prevalence of Antimicrobial Resistance in Klebsiella pneumoniae, Enterobacter cloacae, and Escherichia coli Isolates among Stillbirths and Deceased Under-Five Children in Sierra Leone: Data from the Child Health and Mortality Prevention Surveillance Sites from 2019 to 2022.

Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae are associated with most nosocomial infections worldwide. Although gaps remain in the knowledge of their susceptibility patterns, these are in antimicrobial stewardship. This study aimed to describe antimicrobial susceptibility profiles of the above organisms isolated from postmortem blood from stillbirths and under-five children enrolled in the Child Health and Mortality Prevention Surveillance (CHAMPS) program in Sierra Leone. This was a surveillance study of bacteria isolates from postmortem blood cultures taken within 24 h of death from stillbirths and children aged 0-59 months between March 2019 and February 2022. This was followed by identification and antibiotic sensitivity testing using Becton Dickinson Phoenix M50 (USA). Descriptive analysis was used to characterize the isolates and their antimicrobial susceptibility patterns. Of 367 isolates, K. pneumoniae was the most frequently isolated organism (n = 152; 41.4%), followed by E. coli (n = 40; 10.9%) and E. cloacae (n = 35; 9.5%). Using BACTEC™ FX 40 (Franklin Lakes, NJ, USA), 367 isolates were identified from blood using bacteriological methods. Extended spectrum beta-lactamase (ESBL) was observed in 143 (94.1%) of K. pneumoniae isolates and 27 (65.5%) of E. coli isolates. Carbapenem-resistant organisms (CRO) were seen in 31 (20.4%) of K. pneumoniae and 5 (12.5%) of E. coli isolates. A multidrug resistance (MDR) pattern was most prevalent in E.cloacae (33/35; 94.3%), followed by K. pneumoniae (138/152; 90.8%). Our study showed a high prevalence of multidrug resistance among bacterial isolates in the catchment areas under surveillance by the CHAMPS sites in Sierra Leone.

Green Tea Catechin Epigallocatechin Gallate Inhibits Vegetative Cell Outgrowth and Expression of Beta-Lactamase Genes in Penicillin-Resistant Bacillus anthracis Strain PCr.

The green tea catechin epigallocatechin gallate (EGCg) has antimicrobial effects on many bacteria. In this study, we investigated the inhibitory effects of EGCg on Bacillus anthracis spores and vegetative cells. The B. anthracis spores were insensitive to EGCg, but the growth of vegetative cells derived from germinated spores was inhibited by EGCg. Moreover, EGCg decreased the minimum inhibitory concentration of penicillin and meropenem for penicillin-resistant B. anthracis. In the penicillin-resistant B. anthracis strain, the transcription levels of the beta-lactamase genes (bla1 and bla2) decreased significantly following the treatment with 50 µg/mL EGCg. These results suggest that the appropriate application of EGCg may effectively control the penicillin-resistant B. anthracis growth and beta-lactamase production.

Adverse obstetric outcomes in cases of meconium-stained amniotic fluid complicated with intrapartum fever.

PURPOSE: Meconium-stained amniotic fluid (MSAF) often signifies colonization of the amniotic sac by microorganisms. This study investigated additional adverse obstetric outcomes associated with MSAF in deliveries complicated by maternal intrapartum fever (IF). METHODS: This retrospective study included all singleton pregnancies from 2014 to 2020, with intrapartum maternal fever ≥ 38 °C during a trial of labor. In accordance with departmental protocol, all patients received intravenous antibiotic therapy consisting of ampicillin and gentamicin in the absence of allergies to these medications. Subsequent antibiotic therapy was adjusted based on the culture results. Antibiotic treatment was discontinued postpartum after 48 h without fever. Swab cultures were obtained immediately postpartum from both the maternal and fetal sides of the placenta. Maternal and fetal outcomes, along with positive placental cultures, were compared between participants with MSAF&IF and those with clear amniotic fluid &IF (control group). RESULTS: In comparison to the control group (n = 1089), the MSAF&IF group (n = 264) exhibited significantly higher rates of cesarean delivery (CD) (p = 0.001), CD due to non-reassuring fetal heart rate (p = 0.001), and cord pH ≤ 7.1 (p = 0.004). Positive swab cultures from the placental maternal and fetal sides were more prevalent among the MSAF&IF group (23.1% vs. 17.6%, p = 0.041 and 29.2% vs. 22.9%, p = 0.032, respectively). Placental cultures yielding gastrointestinal pathogens and extended spectrum beta-lactamase were notably more common in the MSAF&IF group compared to controls (p = 0.023). However, there was no significant difference between groups regarding the rate of group B streptococcus positive placental cultures. CONCLUSIONS: Women experiencing IF and MSAF during labor face an elevated risk of CD compared to those with IF alone. The presence of MSAF heightens the risk of positive placental cultures, particularly with gastrointestinal and extended spectrum beta-lactamase pathogens.

Retrospective ANalysis of multi-drug resistant Gram-nEgative bacteRia on veno-venous extracorporeal membrane oxygenation. The multicenter RANGER STUDY.

BACKGROUND: Veno-venous extracorporeal membrane oxygenation (V-V ECMO) is a rapidly expanding life-support technique worldwide. The most common indications are severe hypoxemia and/or hypercapnia, unresponsive to conventional treatments, primarily in cases of acute respiratory distress syndrome. Concerning potential contraindications, there is no mention of microbiological history, especially related to multi-drug resistant (MDR) bacteria isolated before V-V ECMO placement. Our study aims to investigate: (i) the prevalence and incidence of MDR Gram-negative (GN) bacteria in a cohort of V-V ECMOs; (ii) the risk of 1-year mortality, especially in the case of predetected MDR GN bacteria; and (iii) the impact of annual hospital V-V ECMO volume on the probability of acquiring MDR GN bacteria. METHODS: All consecutive adults admitted to the Intensive Care Units of 5 Italian university-affiliated hospitals and requiring V-V ECMO were screened. Exclusion criteria were age < 18 years, pregnancy, veno-arterial or mixed ECMO-configuration, incomplete records, survival < 24 h after V-V ECMO. A standard protocol of microbiological surveillance was applied and MDR profiles were identified using in vitro susceptibility tests. Cox-proportional hazards models were applied for investigating mortality. RESULTS: Two hundred and seventy-nine V-V ECMO patients (72% male) were enrolled. The overall MDR GN bacteria percentage was 50%: 21% (n.59) detected before and 29% (n.80) after V-V ECMO placement. The overall 1-year mortality was 42%, with a higher risk observed in predetected patients (aHR 2.14 [1.33-3.47], p value 0.002), while not in 'V-V ECMO-acquired MDR GN bacteria' group (aHR 1.51 [0.94-2.42], p value 0.090), as compared to 'non-MDR GN bacteria' group (reference). Same findings were found considering only infections. A larger annual hospital V-V ECMO volume was associated with a lower probability of acquiring MDR GN bacteria during V-V ECMO course (aOR 0.91 [0.86-0.97], p value 0.002). CONCLUSIONS: 21% of MDR GN bacteria were detected before; while 29% after V-V ECMO connection. A history of MDR GN bacteria, isolated before V-V ECMO, was an independent risk factor for mortality. The annual hospital V-V ECMO volume affected the probability of acquiring MDR GN bacteria. Trial Registration ClinicalTrial.gov Registration Number NCTNCT06199141, date 12.26.2023.

Gram-negative bacterial colonization in the gut: Isolation, characterization, and identification of resistance mechanisms.

BACKGROUND: The gut microbiome is made up of a diverse range of bacteria, especially gram-negative bacteria, and is crucial for human health and illness. There is a great deal of interest in the dynamic interactions between gram-negative bacteria and their host environment, especially considering antibiotic resistance. This work aims to isolate gram-negative bacteria that exist in the gut, identify their species, and use resistance-associated gene analysis to define their resistance mechanisms. METHODS: Samples were collected from all patients who had a stool culture at a tertiary care center in Lebanon. Each type of bacteria that was identified from the stool samples was subjected to critical evaluations, and all discovered strains underwent antimicrobial susceptibility testing. Polymerase chain reaction was used to profile the genes for Carbapenem-resistant Enterobacteriaceae (CRE), Extended-spectrum beta-lactamase (ESBL), and that of Pseudomonas aeruginosa strains. RESULTS: Escherichia coli, Klebsiella species, and Pseudomonas aeruginosa turned out to be the predominant microbiota members. Escherichia coli strains had a high frequency of extended-spectrum beta-lactamase genes, with the most discovered gene being bla CTX-M. Additionally, a considerable percentage of isolates had carbapenemase-resistant Enterobacteriaceae genes, suggesting the rise of multidrug-resistant strains. Multidrug resistance genes, such as bla mexR, bla mexB, and bla mexA, were found in strains of Pseudomonas aeruginosa, highlighting the possible difficulties in treating infections brought on by these bacteria. CONCLUSION: The findings highlight the critical importance of effective surveillance and response measures to maintain the effectiveness of antibiotics considering the introduction of multidrug resistance genes in Pseudomonas aeruginosa and ESBL and CRE genes in Escherichia coli.

ARGONAUT-III and -V: susceptibility of carbapenem-resistant Klebsiella pneumoniae and multidrug-resistant Pseudomonas aeruginosa to the bicyclic boronate ß-lactamase inhibitor taniborbactam combined with cefepime.

Taniborbactam, a bicyclic boronate ß-lactamase inhibitor with activity against Klebsiella pneumoniae carbapenemase (KPC), Verona integron-encoded metallo-ß-lactamase (VIM), New Delhi metallo-ß-lactamase (NDM), extended-spectrum beta-lactamases (ESBLs), OXA-48, and AmpC ß-lactamases, is under clinical development in combination with cefepime. Susceptibility of 200 previously characterized carbapenem-resistant K. pneumoniae and 197 multidrug-resistant (MDR) Pseudomonas aeruginosa to cefepime-taniborbactam and comparators was determined by broth microdilution. For K. pneumoniae (192 KPC; 7 OXA-48-related), MIC90 values of ß-lactam components for cefepime-taniborbactam, ceftazidime-avibactam, and meropenem-vaborbactam were 2, 2, and 1 mg/L, respectively. For cefepime-taniborbactam, 100% and 99.5% of isolates of K. pneumoniae were inhibited at ≤16 mg/L and ≤8 mg/L, respectively, while 98.0% and 95.5% of isolates were susceptible to ceftazidime-avibactam and meropenem-vaborbactam, respectively. For P. aeruginosa, MIC90 values of ß-lactam components of cefepime-taniborbactam, ceftazidime-avibactam, ceftolozane-tazobactam, and meropenem-vaborbactam were 16, >8, >8, and >4 mg/L, respectively. Of 89 carbapenem-susceptible isolates, 100% were susceptible to ceftolozane-tazobactam, ceftazidime-avibactam, and cefepime-taniborbactam at ≤8 mg/L. Of 73 carbapenem-intermediate/resistant P. aeruginosa isolates without carbapenemases, 87.7% were susceptible to ceftolozane-tazobactam, 79.5% to ceftazidime-avibactam, and 95.9% and 83.6% to cefepime-taniborbactam at ≤16 mg/L and ≤8 mg/L, respectively. Cefepime-taniborbactam at ≤16 mg/L and ≤8 mg/L, respectively, was active against 73.3% and 46.7% of 15 VIM- and 60.0% and 35.0% of 20 KPC-producing P. aeruginosa isolates. Of all 108 carbapenem-intermediate/resistant P. aeruginosa isolates, cefepime-taniborbactam was active against 86.1% and 69.4% at ≤16 mg/L and ≤8 mg/L, respectively, compared to 59.3% for ceftolozane-tazobactam and 63.0% for ceftazidime-avibactam. Cefepime-taniborbactam had in vitro activity comparable to ceftazidime-avibactam and greater than meropenem-vaborbactam against carbapenem-resistant K. pneumoniae and carbapenem-intermediate/resistant MDR P. aeruginosa.

Modified Carbapenem Inactivation Method and Ethylenediaminetetraacetic Acid (EDTA)-Carbapenem Inactivation Method for Detection of Carbapenemase-Producing Enterobacterales and Pseudomonas aeruginosa.

INTRODUCTION: The rising incidence of carbapenem resistance in Enterobacterales and Pseudomonas aeruginosa is a concern. Since carbapenemase production is the primary resistance mechanism, detecting and identifying the genes responsible for it is crucial to effectively monitor its spread. OBJECTIVE: This study aims to detect positivity for the modified carbapenem inactivation method (mCIM) and ethylenediaminetetraacetic acid (EDTA)-carbapenem inactivation method (eCIM) for the detection of carbapenemase-producing Enterobacterales and Pseudomonas aeruginosa. METHODS: Methods: A cross-sectional study was carried out at a tertiary care hospital, including 250 clinical isolates of Enterobacterales and Pseudomonas aeruginosa. These isolates exhibited resistance to at least one of the carbapenems as determined by the VITEK AST 2 System (bioMérieux, USA). The isolates were subjected to mCIM testing, and those that tested positive were further tested using eCIM. The results were interpreted in accordance with the guidelines provided by the Clinical and Laboratory Standards Institute (CLSI) 2023. RESULTS: Out of the total 250 carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa isolates, 151 (60.4%) were Klebsiella pneumonia, 44 (17.6%) were Escherichia coli, 10 (4.0%) were Enterobacter cloacae, 6 (2.4%) were Providencia spp., 4 (1.6%) were Serratia marcescens, 4 (1.6%) were Proteus mirabilis and 31 (12.4%) were Pseudomonas aeruginosa. Positivity for the mCIM was observed in 96% (240 out of 250) of the isolates. Of the mCIM-positive isolates, 234 (97.5%) also tested positive for eCIM, indicating metallo-ß-Lactamase (MLB) production. A statistically significant association was found between both mCIM and eCIM positivity and the degree of resistance to carbapenem (p<0.05). Conclusion: This study shows that the inexpensive method, a combination of mCIM and eCIM assists in differentiating between serine carbapenemase producers and MLB producers, thereby guiding the selection of appropriate therapy and useful in infection control in resource-limited settings.

Prevalence and characterization of quinolone resistance and integrons in clinical Gram-negative isolates from Gaza strip, Palestine.

BACKGROUND: Gram-negative bacteria with quinolone resistance and extended-spectrum beta-lactamases (ESBLs) present significant treatment challenges. This study evaluated the prevalence and characteristics of quinolone resistance in Gram-negative strains, investigating the relationship between plasmid-mediated quinolone resistance (PMQR), ESBLs, and integrons. METHODS AND RESULTS: We collected 146 Gram-negative isolates from patients in three Palestinian hospitals. For quinolone resistance isolates, the presence and characterization of PMQR, ß-lactamase genes and integrons were studied by PCR and sequencing. Out of 146 clinical isolates, 64 (43.8%) were resistant to quinolones, with 62 (97%) being multidrug-resistant (MDR) and 33 (51.5%) ESBL-producers. PMQR-encoding genes were present in 45 (70.3%) isolates, including aac(6')-Ib-cr (26.6%), qnrA (18.8%), qnrS1 (20.8%), and qnrB (6.4%). BlaCTX-M genes were detected in 50% (32/64) of isolates, with blaCTX-M-15 being the most common. BlaTEM-1, blaSHV-1 and blaVIM genes were found in 13, 6, and 4 isolates, respectively. Class I integrons were found in 31/64 (48%) of isolates, with 14 containing gene cassettes conferring resistance to trimethoprim (dhfr17, dfrA12, dfrA1) and aminoglycosides resistance genes (aadA1, aadA2, aadA5, and aadA6). CONCLUSIONS: This study found a high rate of quinolone resistance, ESBL and integrons in clinical Gram-negative isolates from our hospitals. Urgent measures are crucial, including implementing an antimicrobial resistance surveillance system, to control and continuously monitor the development of antimicrobial resistance.

New Delhi Metallo-Beta-Lactamase Inhibitors: A Systematic Scoping Review.

Background/Objectives: Among various carbapenemases, New Delhi metallo-beta-lactamases (NDMs) are recognized as the most powerful type capable of hydrolyzing all beta-lactam antibiotics, often conferring multi-drug resistance to the microorganism. The objective of this review is to synthesize current scientific data on NDM inhibitors to facilitate the development of future therapeutics for challenging-to-treat pathogens. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews, we conducted a MEDLINE search for articles with relevant keywords from the beginning of 2009 to December 2022. We employed various generic terms to encompass all the literature ever published on potential NDM inhibitors. Results: Out of the 1760 articles identified through the database search, 91 met the eligibility criteria and were included in our analysis. The fractional inhibitory concentration index was assessed using the checkerboard assay for 47 compounds in 37 articles, which included 8 compounds already approved by the Food and Drug Administration (FDA) of the United States. Time-killing curve assays (14 studies, 25%), kinetic assays (15 studies, 40.5%), molecular investigations (25 studies, 67.6%), in vivo studies (14 studies, 37.8%), and toxicity assays (13 studies, 35.1%) were also conducted to strengthen the laboratory-level evidence of the potential inhibitors. None of them appeared to have been applied to human infections. Conclusions: Ongoing research efforts have identified several potential NDM inhibitors; however, there are currently no clinically applicable drugs. To address this, we must foster interdisciplinary and multifaceted collaborations by broadening our own horizons.

Detection of Klebsiella pneumoniae Carbapenem Resistance Genes by qPCR: Choosing the Right Method for Total DNA Extraction.

Rapid and accurate detection of Klebsiella pneumoniae carbapenem resistance is important for infection control and targeted antibiotic therapy. PCR-based assay performance heavily depends on the quality and quantity of template DNA. Challenges arise from the necessity to isolate chromosomal and large plasmid-encoded resistance genes simultaneously from a limited number of target cells and to remove PCR inhibitors. qPCRs for the detection of K. pneumoniae strains carrying blaOXA-48, blaNDM-1, blaKPC-2, and blaVIM-1 carbapenemase genes were developed. We compared the performance of template DNA extracted with silica column-based methods, reversed elution systems, and lysis-only methods either from diluted culture fluid or from a synthetic stool matrix which contained PCR inhibitors typically present in stool. The synthetic stool matrix was chosen to mimic K. pneumoniae containing rectal swabs or stool samples in a reproducible manner. For total DNA isolated from culture fluid, resistance gene detection by qPCR was always possible, independent of the extraction method. However, when total DNA was isolated from synthetic stool matrix spiked with K. pneumoniae, most methods were insufficient. The best performance of template DNA was obtained with reversed elution. This highlights the importance of choosing the right DNA extraction method for consistent carbapenem resistance detection by PCR.