β-lactam resistance associated with β-lactamase production and porin alteration in clinical isolates of E. coli and K. pneumoniae

The prevalence of antibiotic-resistant fecal bacteria in recreational aquatic environments: phenotypic and molecular approach

The rising incidence of antibiotic resistance poses a significant threat to public health. In recent years the widespread use of antibiotics has led to an increase in the concentration of antibiotic-resistant bacteria also in natural environments. The study was conducted in bathing areas three recreational lakes located in the Zaborski Landscape Park in northern Poland. Water samples were collected in three parallel repetitions in April, June and September 2022. Our study indicates that anthropopressure connected with tourism and recreation promotes the growth of fecal bacteria, including antibiotic-resistant strains, whose significant accumulation was recorded in September, the month marking the end of summer vacation. Antibiotic resistance profiles showed that isolated strains of fecal bacteria were resistant to beta-lactam antibiotics. The highest percentage of Escherichia coli strains showed resistance to cefepime (39.1%), and enterococci to imipenem (26.9%). The amplification of resistance genes confirmed the presence of only selected bla genes in the examined strains of fecal bacteria. The blaTEM gene was found in 14 strains of Enterococcus faecium (82.4%), in all 4 isolates of Enterococcus faecalis, and in 4 out of 5 unspecified strains of fecal streptococci. In Escherichia coli only blaCTX gene was identified in one strain. The presence of blaTEM genes was strongly correlated with the concentration of fecal bacteria, it can therefore be assumed that the presence of resistance genes was caused by direct contamination of the studied lakes with feces containing antibiotic-resistant bacteria, presumably without contamination from other sources. Resistance genes found in the control strains from sewage treatment plants were not identified in the studied isolates. Antibiotic resistance genetic markers found in strains isolated from wastewater may prove helpful in determining the sources of contamination of natural aquatic ecosystems with antibiotic-resistant fecal bacteria and thus ensure efficient management of projects aimed at making these waterbodies available for public use.

Emerging threats: Antimicrobial resistance in extended-spectrum beta-lactamase and carbapenem-resistant Escherichia coli

Antimicrobial resistance (AMR) in Escherichia coli strains, particularly those producing Extended-Spectrum Beta-Lactamase (ESBL) and Carbapenemase (CR-Ec), represents a serious global health threat. These resistant strains have been associated with increased morbidity, mortality, and healthcare costs, as they limit the effectiveness of standard antibiotic therapies. The prevalence of ESBL- and CR-Ec-producing strains continues to rise, driven by the overuse and misuse of antibiotics in healthcare and agricultural settings, and facilitated by global interconnectedness through international travel, trade, and food distribution. This review article examines the molecular mechanisms behind ESBL and CR resistance, focusing on the key genes involved in these processes, such as blaCTX-M, blaKPC, and blaNDM, and the clinical challenges posed by these strains. Additionally, the public health impact, including the spread of infections in hospital and community environments, is highlighted. The discussion emphasizes the urgent need for improved diagnostic tools, robust surveillance systems, and innovative therapeutic strategies. Emerging treatments, including phage therapy and novel antibiotic combinations, show promise in addressing these challenges and offer potential breakthroughs in combating resistant strains. Lastly, the review calls for stronger antimicrobial stewardship and policy reforms to mitigate the spread of resistant E. coli strains and protect global public health. Effective intervention at multiple levels, from diagnostics to policy, is critical to controlling the threat posed by AMR.

Resistome phylodynamics of multidrug-resistant Shigella isolated from diarrheal patients

Multi-drug resistance (MDR) in Shigella continues to pose a significant public health challenge, particularly in developing countries. Recent advances in genomics strengthen the surveillance of MDR-pathogens and antimicrobial resistance (AMR) mediators. However, genome-based investigations into resistome dynamics in Shigella are limited, specifically in Bangladesh. Therefore, we investigated MDR-Shigella resistomes to evaluate their AMR transmission and phylodynamics. Clinical Shigella strains were screened for MDR phenotypes through susceptibility tests against 28 antibiotics from 10 different classes. Whole-genome sequencing (WGS) and bioinformatics approaches were performed to unveil the resistome dynamics: >500 global plasmid entities and >1,000 plasmid-mediated resistance gene clusters from global databases were included in this study. We identified 28 distinct antimicrobial resistance genes (ARGs) from nine antibiotic classes, with 75% originating from plasmids. Notably, two conjugative MDR plasmids included nearly all potential ARGs, conferring resistance to first-line drugs for shigellosis. Two third-generation cephalosporin-resistant [wubC-blaCTX-M-15-ISEcp1 and blaTEM-1] and two macrolide-resistant mobile genomic islands (GIs) [mphA-mrx-mph(R)A-IS6100 and mphE-msrE-IS482-IS6] had emerged in Shigella in Bangladesh. In addition, trimethoprim-aminoglycoside-streptothricin-sulfonamide-resistant dfrA1-sat1-aadA1 and aph3-dfrA14-aph6-sul2 were in conjugative plasmids in Bangladesh. The MDR plasmids and resistant GIs were phylogenetically relevant to Europe, USA, or China-derived isolates, indicating carry-over of the emerging ARGs from heavily industrialized countries and MSM-burdened (men who have sex with men) populations. The global burden of resistance GIs has increased sharply, especially after 2014. Emerging resistance mediators were most frequent (>80%) in human-associated Escherichia coli and Klebsiella pneumoniae. We infer ARGs horizontally propagate among Enteropathogens: informing treatment strategies and supporting policymakers in strengthening AMR-containment efforts utilizing the phylodynamics network.IMPORTANCEThe world is suffering from a high burden of MDR enteropathogens. Healthcare providers in low- and middle-income countries (LMICs) often face trouble finding effective drugs among the many antibiotics introduced in diarrheal treatment. Resistance-mediated drug inactivation is more rapid than the advent of new antimicrobials, leaving enteritis treatment on the edge. In Bangladesh, where one-third of users are self-prescribing antibiotics and thousands are dying due to resistance-related treatment failure, phylogenomic evidence of AMR transmission root is scarce. Therefore, investigating the resistomes of MDR-Shigella, the leading cause of diarrheal deaths in Bangladesh, is crucial. We identified several emerging resistance mediators and their phylogenetic links to global entities, which is significant for improving shigellosis treatment and enhancing AMR containment strategies. Understanding the MDR mechanism in Shigella will help physicians choose effective drugs and anticipate resistance-mediated changes in treatment approaches; the spatiotemporal phylodynamics of AMR mediators aid policymakers in setting effective checkpoints in the AMR transmission network.

Wastewater microbiology: occurrence and prevalence of antibiotic-resistant extended-spectrum β-lactamase-producing Enterobacteriaceae in the district wastewater system

Extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, including Klebsiella pneumoniae and Escherichia coli, pose a serious risk to human health because of antibiotic resistance. Wastewater serves as a reservoir for these bacteria, contributing to the evolution and transmission of antibiotic-resistant strains. The research aims to identify ESBL bacterium in wastewater samples from District Kohat. K. pneumoniae and E. coli were confirmed as ESBL-producing bacteria through a comprehensive array of diagnostic procedures, including Gram staining, biochemical analyses, and antibiotic susceptibility testing. Fecal coliform count (FCC) analyses revealed varying microorganism levels. Both E. coli and K. pneumoniae isolates showed ESBL enzyme expression, indicating antibiotic resistance. Resistance patterns included ciprofloxacin, ampicillin, cefotaxime, cefoxitin, and amoxicillin-clavulanic acid for both species. E. coli displayed higher sensitivity for chloramphenicol, trimethoprim- sulfamethoxazole, and gentamicin. Ceftazidime minimum inhibitory concentration results showed E. coli's higher resistance. The study accentuates the presence of antibiotic-resistant strains, emphasizing the value of effective wastewater treatment. The study provides crucial insights into microbial characteristics, fecal contamination, ESBL production, and antibiotic resistance in E. coli and K. pneumoniae isolates, advocating for monitoring and mitigation strategies.

Prevalence and molecular characterization of ESBL-producing Enterobacteriaceae in Egypt: a systematic review and meta-analysis of hospital and community-acquired infections

BACKGROUND

ESBL-producing Enterobacteriaceae (ESBL-PE) represent a significant global health threat. In response to this growing concern and the lack of a surveillance system for ESBL-PE infections in Egypt, we conducted this meta-analysis. In this study, we aimed to quantify the prevalence of ESBL-PE based on the source of infection and characterize their molecular dissemination. Additionally, we sought to uncover temporal trends to assess the spread of ESBL-PE over time.

METHODS

A comprehensive literature search was conducted in PubMed, Scopus, Google Scholar, Web of Science, and the Egyptian Knowledge Bank to identify studies that: (1) report the prevalence of ESBL-PE in Egypt; (2) use valid detection methods; (3) involve clinical specimens; and (4) were published between 2010 and 2024. The quality of the included studies was evaluated using the "Joanna Briggs Institute Critical Appraisal Checklist". Meta-analysis was performed using the R meta package, reporting pooled prevalence with 95% confidence intervals (CI) via a random effects model.

RESULTS

This meta-analysis included 34 studies with 4,528 isolates, spanning 2007 to 2023. The overall prevalence of ESBL-PE in Egypt was 60% (95% CI: 54-65). The leave-one-out meta-analysis demonstrated the absence of influential outliers and Egger's test indicated no evidence of publication bias (P = 0.25). The prevalence of ESBL-PE was 62% (95% CI: 55-68) in nosocomial infections and 65% (95% CI: 52-75) in community-acquired infections, with no statistically significant difference (P = 0.68). The prevalence of ESBL producers in E. coli (64%) and K. pneumoniae (63%) is higher than in Proteus mirabilis (46%) (P = 0.06). Temporal analysis showed a stable ESBL prevalence over time. Moreover, in phenotypically confirmed ESBL-producing, E. coli harboring blaCTX-M was most prevalent (73%), followed by blaTEM (60%) and blaSHV (22%), with significant differences (P < 0.01). Subsequent analysis identified blaCTX-M-15 as the predominant variant of the blaCTX-M gene.

CONCLUSIONS

The prevalence of ESBL-PE in Egypt is alarmingly high at 60%. The observed high rates in both hospital and community-acquired infections underscore the need for public health strategies targeting both settings. One limitation of this study is the high heterogeneity, which partly attributed to regional and institutional variations in antibiotic use and stewardship practices.

High prevalence of colonization with extended-spectrum β-lactamase-producing and multidrug-resistant Enterobacterales in the community in Addis Ababa Ethiopia: risk factors, carbapenem resistance, and molecular characterization

BACKGROUND

Globally, extended-spectrum beta-lactamase-producing and carbapenem-resistant Enterobacterales are major causes of hospital-acquired infections and there are increasing concerns about their role in community-acquired infections.

OBJECTIVE

We aimed to investigate the prevalence of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) and Carbapenemase-producing-Carbapenemresistant-Enterobacterales (CP-CRE) and associated factors in community settings in Gulele sub city, Addis Ababa, Ethiopia.

METHODS

A cross-sectional study was conducted among 261 healthy individuals. Stool samples were collected and processed using standard microbiological methods. Antimicrobial susceptibility and phenotypic ESBL and carbapenemase tests were performed. Antibiotic resistance genes were detected by Polymerase Chain Reaction (PCR).

RESULTS

The colonization rate of ESBL-PE and CP-CRE were 31.4% (82/261, 95% CI: 25.91-37.48) and 0.8% (2/261, 95% CI: 0.13-3.1), respectively by phenotypic method. Molecular detection of genes for ESBL-PE was 27.9% (73/261, 95% CI:22.7-33.9), and for CP-CRE was 0.8% (2/261, 95% CI: 0.13-3.1). The most prevalent genes were blaTEM [76.7% (56/73)] and blaCTX-M [45.2% (33/73)]. Previous antibiotic use (AOR:2.04, 95%CI: 1.35-4.41, P:0.041) and age between 42 and 53 years old (AOR:3.00, 95%CI:1.12-7.48, P:0.019) were significantly associated with ESBL-PE colonization.

CONCLUSION

Intestinal colonization by ESBL-PE harboring the associated antibiotic resistance genes was substantially high but with low CP-CRE. Continued surveillance of community-level carriage of antimicrobial resistance Enterobacterales is warranted.

Genetic determinants of increased sodium hypochlorite and ciprofloxacin susceptibility in Pseudomonas aeruginosa PA14 biofilms

Reactive chlorine species (RCS) like sodium hypochlorite (NaOCl) are potent oxidizing agents and widely used biocides in surface disinfection, water treatment, and biofilm elimination. Moreover, RCS are also produced by the human immune system to kill invading pathogens. However, bacteria have developed mechanisms to survive the damage caused by RCS. Using the comprehensive Pseudomonas aeruginosa PA14 transposon mutant library in a genetic screen, we identified a total of 28 P. aeruginosa PA14 mutants whose biofilms showed increased susceptibility to NaOCl in comparison to PA14 WT biofilms. Of these, ten PA14 mutants with a disrupted apaH, PA0793, acsA, PA1506, PA1547, PA3728, yajC, queA, PA3869, or PA14_32840 gene presented a 4-fold increase in NaOCl susceptibility compared to wild-type biofilms. While none of these mutants showed a defect in biofilm formation or attenuated susceptibility of biofilms toward the oxidant hydrogen peroxide (H2O2), all but PA14_32840 also exhibited a 2-4-fold increase in susceptibility toward the antibiotic ciprofloxacin. Further analyses revealed attenuated levels of intracellular ROS and catalase activity only for the apaH and PA1547 mutant, providing insights into the oxidative stress response in P. aeruginosa biofilms. The findings of this paper highlight the complexity of biofilm resistance and the intricate interplay between different mechanisms to survive oxidative stress. Understanding resistance strategies adopted by biofilms is crucial for developing more effective ways to fight resistant bacteria, ultimately contributing to better management of bacterial growth and resistance in clinical and environmental settings.

Prevalence of antibiotic resistance genes in bacteria from Gomti and Ganga rivers: implications for water quality and public health

Rivers serve as a significant habitat and water sources for diverse organisms, including humans. An important environmental and public health concern is the increase in antibiotic-resistant bacteria (ARBs) and genes (ARGs) in aquatic ecosystems brought about by excessive pollutant flow. The research highlighted that river water, which is receiving discharge from wastewater treatment plants, is harbouring multidrug-resistant bacteria. River water samples were collected in January, April, July and October 2022 from three separate locations of each Gomti and Ganga river. A total of 114 bacteria were isolated from Gomti as well as the Ganga River. All the isolates were tested for their resistance to various antibiotics by disc diffusion method. The isolated bacteria were tested for the antibiotic resistance genes using PCR and were identified by 16s rRNA sequencing. The ARBs percentages for each antibiotic were as follows: ampicillin (100%); cefotaxime (96.4, 63.1%); erythromycin (52.6, 57.8%); amikacin (68.4, 50.8%); tetracycline (47.3, 54.3%); nalidixic acid (47.3, 45.6%); streptomycin (68.4, 49.1%); gentamycin (43.8, 35%); chloramphenicol (26.3, 33.3%); neomycin (49.1, 29.8%) and ciprofloxacin (24.5, 7.01%). Further, antibiotic resistance genes in Gomti and Ganga water samples disclose distinctive patterns, including resistance to ermB (25, 40%); tetM (25, 33.3%); ampC (44.4, 40%) and cmlA1 (16.6%). Notably cmlA1 resistant genes were absent in all bacterial strains of the Gomti River. Additionally, gyrA gene was not found in both the river water samples. The presence of ARGs in the bacteria from river water shows threat of transferring these genes to native environmental bacteria. To protect the environment and public health, constant research is necessary to fully understand the extent and consequences of antibiotic resistance in these aquatic habitats.

Assessment of antibacterial activity, modes of action, and synergistic effects of Origanum vulgare hydroethanolic extract with antibiotics against avian pathogenic Escherichia coli

This study evaluates the antibacterial effectiveness of Origanum vulgare hydroethanolic extract, both independently and in combination with antibiotics, against Escherichia coli strains associated with avian colibacillosis-a significant concern for the poultry industry due to the rise of antibiotic-resistant E. coli. The urgent demand for new treatments is addressed by analyzing the extract's phytochemical makeup via High-Performance Liquid Chromatography (HPLC), which identified sixteen phenolic compounds. Antibacterial activity was determined through agar diffusion and the measurement of minimum inhibitory and bactericidal concentrations (MIC and MBC), showing moderate efficacy (MIC: 3.9 to 7.8 mg/mL, MBC: 31.2 to 62.4 mg/mL). Combining the extract with antibiotics like ampicillin and tetracycline amplified antibacterial activity, indicating a synergistic effect and highlighting the importance of combinatory treatments against resistant strains. Further analysis revealed the extract's mechanisms of action include disrupting bacterial cell membrane integrity and inhibiting ATPase/H+ proton pumps, essential for bacterial survival. Moreover, the extract effectively inhibited and eradicated biofilms, crucial for preventing bacterial colonization. Regarding cytotoxicity, the extract showed no hemolytic effect at 1 to 9 mg/mL concentrations. These results suggest Origanum vulgare extract, particularly when used with antibiotics, offers a promising strategy for managing avian colibacillosis, providing both direct antibacterial benefits and moderating antibiotic resistance, thus potentially reducing the economic impact of the disease on the poultry industry.

Characterization and genetic analysis of extensively drug-resistant hospital acquired Pseudomonas aeruginosa isolates

BACKGROUND

The incidence of hospital-acquired infections in extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) has been increasing worldwide and is frequently associated with an increase in mortality and morbidity rates. The aim of this study was to characterize clinical XDR-PA isolates recovered during six months at three different hospitals in Egypt.

RESULTS

Seventy hospital-acquired clinical isolates of P. aeruginosa were classified into multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR), according to their antimicrobial resistance profile. In addition, the possession of genes associated with mobile genetic elements and genes encoding antimicrobial resistance determinants among isolates were detected using polymerase chain reaction. As a result, a significant percentage of the isolates (75.7%) were XDR, while 18.5% were MDR, however only 5.7% of the isolates were non-MDR. The phenotypic detection of carbapenemases, extended-spectrum β-lactamases (ESBLs) and metallo β-lactamase (MBL) enzymes showed that 73.6% of XDR-PA isolates were carbapenemases producers, whereas 75.5% and 88.7% of XDR-PA isolates produced ESBLs and MBL respectively. In addition, PCR screening showed that oxa gene was the most frequently detected gene of carbapenemases (91.4%), while aac(6')-lb gene was mostly detected (84.3%) among the screened aminoglycosides-resistance genes. Furthermore, the molecular detection of the colistin resistance gene showed that 12.9% of isolates harbored mcr-1 gene. Concerning mobile genetic element markers (intI, traA, tnp513, and merA), intI was the highest detected gene as it was amplified in 67 isolates (95.7%). Finally, phylogenetic and molecular typing of the isolates via ERIC-PCR analysis revealed 10 different ERIC fingerprints.

CONCLUSION

The present study revealed a high prevalence of XDR-PA in hospital settings which were resistant to a variety of antibiotics due to several mechanisms. In addition, 98% of the XDR-PA clinical isolates contained at least one gene associated with movable genetic elements, which could have aided the evolution of these XDR-PA strains. To reduce spread of drug resistance, judicious use of antimicrobial agents and strict infection control measures are therefore essential.

Upregulation of pmrA, pmrB, pmrC, phoQ, phoP, and arnT genes contributing to resistance to colistin in superbug Klebsiella pneumoniae isolates from human clinical samples in Tehran, Iran

Background

Antibiotic resistance in Klebsiella pneumoniae isolates, particularly resistance to colistin, has become a growing concern. This study seeks to investigate the upregulation of specific genes (pmrA, pmrB, pmrC, phoQ, phoP, and arnT) that contribute to colistin resistance in K. pneumoniae isolates collected from human clinical samples in Tehran, Iran.

Methods

Thirty eight K. pneumoniae isolates were obtained and subjected to antibiotic susceptibility testing, as well as evaluation for phenotypic AmpC and ESBL production according to CLSI guidelines. The investigation of antibiotic resistance genes was conducted using polymerase chain reaction (PCR), whereas the quantification of colistin resistance related genes expressions was performed via Real-Time PCR.

Results

The highest and lowest antibiotics resistance were observed for cefotaxime 33 (86.8%) and minocycline 8 (21.1%), respectively. Twenty-four (63.2%) and 31 (81.6%) isolates carried AmpC and ESBLs, respectively. Also, antibiotic resistance genes containing blaNDM, blaIMP, blaVIM, blaSHV, blaTEM, blaCTXM, qnrA, qnrB, qnrS, and aac(6')-Ib were detected in K. pneumoniae isolates. Only 5 (13.1%) isolates were resistant to colistin and the MIC range of these isolates was between 4 and 64 μg ml-1. Upregulation of the pmrA, pmrB, pmrC, phoQ, phoP, and arnT genes was observed in colistin-resistant isolates. The colistin-resistant isolates were found to possess a simultaneous presence of ESBLs, AmpC, fluoroquinolone, aminoglycoside, and carbapenem resistant genes.

Conclusions

This study reveals escalating antibiotic resistance in K. pneumoniae, with notable coexistence of various resistance traits, emphasizing the need for vigilant surveillance and innovative interventions.

Semi-mechanistic modeling of resistance development to β-lactam and β-lactamase-inhibitor combinations

The use of β-lactam (BL) and β-lactamase inhibitor (BLI) combinations, such as piperacillin-tazobactam (PIP-TAZ) is an effective strategy to combat infections by extended-spectrum β-lactamase-producing bacteria. However, in Gram-negative bacteria, resistance (both mutational and adaptive) to BL-BLI combination can still develop through multiple mechanisms. These mechanisms may include increased β-lactamase activity, reduced drug influx, and increased drug efflux. Understanding the relative contribution of these mechanisms during resistance development helps identify the most impactful mechanism to target in designing a treatment to counter BL-BLI resistance. This study used semi-mechanistic mathematical modeling in combination with antibiotic sensitivity assays to assess the potential impact of different resistance mechanisms during the development of PIP-TAZ resistance in a Klebsiella pneumoniae isolate expressing CTX-M-15 and SHV-1 β-lactamases. The mathematical models were used to evaluate the potential impact of several cellular changes as a sole mediator of PIP-TAZ resistance. Our semi-mechanistic model identified 2 out of the 13 inspected mechanisms as key resistance mechanisms that may independently support the observed magnitude of PIP-TAZ resistance, namely porin loss and efflux pump up-regulation. Simulation using the resulting models also suggested the possible adjustment of PIP-TAZ dose outside its commonly used 8:1 dosing ratio. The current study demonstrated how theory-based mechanistic models informed by experimental data can be used to support hypothesis generation regarding potential resistance mechanisms, which may guide subsequent experimental studies.

Antimicrobial resistance profiles of Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae strains isolated from broiler chickens

Globally, the spread of multidrug-resistant Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae from food to humans poses a severe threat to public health. The aim of this study was to assess the co-occurrence of colistin and β-lactamase resistance genes in E. coli, K. pneumoniae, and P. aeruginosa strains isolated from faeces of abattoir broiler chickens. The E. coli, P. aeruginosa and K. pneumoniae isolates were successfully detected from faecal samples by polymerase chain reaction (PCR) at infection rates of 60.7%, 22.5% and 16.7% respectively. The isolates displayed the highest levels of antibiotic resistance (AR) against ampicillin (82.3%) and amoxicillin-clavulanic acid (74.2%) for E. coli, followed by cefoxitin (70.6%) for K. pneumoniae, whilst P. aeruginosa displayed 26.1% antibiotic resistance (AR) against both ampicillin and colistin sulphate. The colistin mcr-1 gene was harboured by 46.8%, 47.1% and 21.7%, E. coli, K. pneumonia and P. aeruginosa isolates respectively. Ten out of 62 (16.1%), 6/17 (35.3%), 4/23 (17.4%) isolates were phenotypically classified as ESBL E. coli, K. pneumoniae, and P. aeruginosa respectively. The ESBL-E. coli isolates respectively possessed blaCTX-M (60%), blaTEM (20%) and blaCTX-M-9 (10%) genes. The ESBL-K. pneumoniae harboured, blaCTX-M (50%), blaOXA (33%), blaCARB (17%), and blaCTX-M-9 (17%) genes respectively, whilst, P. aeruginosa isolates respectively carried blaTEM (75%), blaCTX-M (50%), blaOXA (25%) and blaCARB (25%) genes. Molecular analysis identified the blaCTX-Mβ-lactamase-encoding genes collectively from E. coli, P. aeruginosa, K. pneumoniae isolates. Colistin and β-lactamase genes were present in only 16.7%, 6.9%, and 2.9% of E. coli, K. pneumoniae, and P. aeruginosa isolates, respectively. A total of 17, 7 and 3 isolates for E. coli, K. pneumoniae and P. aeruginosa respectively carried both colistin and β-lactamase antibiotics resistant genes. This is a public health threat that points to a challenge in the treatment of infections caused by these zoonotic bacteria. Data generated from this study will contribute to formulation of new strategies for combating spread of E. coli, K. pneumoniae, and P. aeruginosa isolates as well as prevention of their AR development.

Fecal Carriage of Colibactin-Encoding Escherichia coli Associated With Colorectal Cancer Among a Student Populace

Fecal carriage of the colibactin (clb) gene in Escherichia coli is described as a source that could promote carcinogenesis, progressing to colorectal cancer. The present study investigated the demographic, dietary, and antibiotic consumption variables as correlates for fecal carriage of clb+/E coli among the student populace. In a randomized cross-sectional survey, E coli (N = 136) from the fecal samples of eligible students were characterized and evaluated for antibiotic resistance, β-lactamase (blm), biofilm, virulence factor production, and strain tryptophan reverse mutagenic activity. The encoded clb+/E coli were analyzed for correlates with principal component analysis. Of all the E coli strains, a low rate of 2 clb+/E coli (1.5%) and higher rates of biofilm (13.2%) and blm producers (11.8%) were recorded among the mutant strains as compared with the nonmutant types. All the clb+/E coli showed complete resistance to amoxicillin, Augmentin (amoxicillin and clavulanate), gentamicin, and trimethoprim/sulfamethoxazole. The fecal clb-encoded E coli (1.5%) were not associated with demographic status, fiber-based food (odds ratio [OR], 1.03; 95% CI, 56.74-138.7; P = .213), alcohol (OR, 1.27; 95% CI, 61.74-147.1; P = .221), antibiotic consumptions (OR, 1.11; 95% CI, 61.29-145.3; P = .222), and handwashing (OR, 1.17; 95% CI, 60.19-145.5; P = .216). The hierarchical cluster of blm+/E coli revealed high-level resistance with a multiantibiotic resistance index ≥0.2 (P < .05). Only 12% of all strains were tryptophan mutant/blm+, and 1.5% of clb+/ECblm+ were observed in fecal samples with a 452-base pair size. Trimethoprim/sulfamethoxazole and biofilm production positively regressed with clb expression (P > .05). Principal component analysis score plot indicated an association of clb+/ECblm+ with dietary pattern, alcohol, blm, and hemolysin production. The combined activity of blm and biofilm production in the gut microbiota could promote clb+/E coli colonization, facilitating genotoxin production and possible colorectal cancer induction.

The global burden of antimicrobial resistance - urinary tract infections

Antimicrobial resistance (AMR) has emerged as a significant global healthcare problem. Antibiotic use has accelerated the physiologic process of AMR, particularly in Gram-negative pathogens. Urinary tract infections (UTIs) are predominantly of a Gram-negative nature. Uropathogens are evolutionarily highly adapted and selected strains with specific virulence factors, suggesting common mechanisms in how bacterial cells acquire virulence and AMR factors. The simultaneous increase in resistance and virulence is a complex and context-dependent phenomenon. Among known AMR mechanisms, the plenitude of different β-lactamases is especially prominent. The risk for AMR in UTIs varies in different patient populations. A history of antibiotic consumption and the physiology of urinary flow are major factors that shape AMR prevalence. The urinary tract is in close crosstalk with the microbiome of other compartments, including the gut and genital tracts. In addition, pharmacokinetic properties and the physiochemical composition of urinary compartments can contribute to the emergence of AMR. Alternatives to antibiotic treatment and a broader approach to address bacterial infections are needed. Among the various alternatives studied, antimicrobial peptides and bacteriophage treatment appear to be highly promising approaches. We herein summarize the present knowledge of clinical and microbiological AMR in UTIs and discuss innovative approaches, namely new risk prediction tools and the use of non-antibiotic approaches to defend against uropathogenic microbes.

Correlation between antimicrobial resistance, biofilm formation, and virulence determinants in uropathogenic Escherichia coli from Egyptian hospital

BACKGROUND

Uropathogenic Escherichia coli (UPEC) is the main etiological agent behind community-acquired and hospital-acquired urinary tract infections (UTIs), which are among the most prevalent human infections. The management of UPEC infections is becoming increasingly difficult owing to multi-drug resistance, biofilm formation, and the possession of an extensive virulence arsenal. This study aims to characterize UPEC isolates in Tanta, Egypt, with regard to their antimicrobial resistance, phylogenetic profile, biofilm formation, and virulence, as well as the potential associations among these factors.

METHODS

One hundred UPEC isolates were obtained from UTI patients in Tanta, Egypt. Antimicrobial susceptibility was assessed using the Kirby-Bauer method. Extended-spectrum β-lactamases (ESBLs) production was screened using the double disk synergy test and confirmed with PCR. Biofilm formation was evaluated using the microtiter-plate assay and microscopy-based techniques. The phylogenetic groups of the isolates were determined. The hemolytic activity, motility, siderophore production, and serum resistance of the isolates were also evaluated. The clonal relatedness of the isolates was assessed using ERIC-PCR.

RESULTS

Isolates displayed elevated resistance to cephalosporins (90-43%), sulfamethoxazole-trimethoprim (63%), and ciprofloxacin (53%). Ninety percent of the isolates were multidrug-resistant (MDR)/ extensively drug-resistant (XDR) and 67% produced ESBLs. Notably, there was an inverse correlation between biofilm formation and antimicrobial resistance, and 31%, 29%, 32%, and 8% of the isolates were strong, moderate, weak, and non-biofilm producers, respectively. Beta-hemolysis, motility, siderophore production, and serum resistance were detected in 64%, 84%, 65%, and 11% of the isolates, respectively. Siderophore production was correlated to resistance to multiple antibiotics, while hemolysis was more prevalent in susceptible isolates and associated with stronger biofilms. Phylogroups B2 and D predominated, with lower resistance and stronger biofilms in group B2. ERIC-PCR revealed considerable diversity among the isolates.

CONCLUSION

This research highlights the dissemination of resistance in UPEC in Tanta, Egypt. The evident correlation between biofilm and resistance suggests a resistance cost on bacterial cells; and that isolates with lower resistance may rely on biofilms to enhance their survival. This emphasizes the importance of considering biofilm formation ability during the treatment of UPEC infections to avoid therapeutic failure and/or infection recurrence.

Phenotypic and Genotypic Characterization of Extended Spectrum Beta-Lactamase-Producing Clinical Isolates of Escherichia coli and Klebsiella pneumoniae in Two Kenyan Facilities: A National Referral and a Level Five Hospital

Background

The emergence of antimicrobial resistance (AMR) and multidrug resistance (MDR) among Escherichia coli and Klebsiella pneumoniae, especially through the production of extended spectrum β-lactamases (ESBLs), limits therapeutic options and poses a significant public health threat.

Objective

The aim of this study was to assess the phenotypic and genetic determinants of antimicrobial resistance of ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates from patient samples in two Kenyan Hospitals.

Methods

We collected 138 E. coli and 127 K. pneumoniae isolates from various clinical specimens at the two health facilities from January 2020 to February 2021. The isolates' ESBL production and antibiotic susceptibility were phenotypically confirmed using a standard procedure. Molecular analysis was done through conventional polymerase chain reaction (PCR) with appropriate primers for gadA, rpoB, blaTEM, blaSHV, blaOXA, blaCTX-M-group-1, blaCTX-M-group-2, blaCTX-M-group-9, and blaCTX-M-group-8/25 genes, sequencing and BLASTn analysis.

Results

Most E. coli (82.6%) and K. pneumoniae (92.9%) isolates were ESBL producers, with the highest resistance was against ceftriaxone (69.6% among E. coli and 91.3% among K. pneumoniae) and amoxicillin/clavulanic acid (70.9% among K. pneumoniae). The frequency of MDR was 39.9% among E. coli and 13.4% among K. pneumoniae isolates. The commonest MDR phenotypes among the E. coli isolates were CRO-FEP-AZM-LVX and CRO-AZM-LVX, while the FOX-CRO-AMC-MI-TGC-FM, FOX-CRO-FEP-AMC-TZP-AZM-LVX-MI and CRO-AMC-TZP-AZM-MI were the most frequent among K. pneumoniae isolates. Notably, the FOX-CRO-FEP-AMC-TZP-AZM-LVX-MI phenotype was observed in ESBL-positive and ESBL-negative K. pneumoniae isolates. The most frequent ESBL genes were blaTEM (42%), blaSHV (40.6%), and blaOXA (36.2%) among E. coli, and blaTEM (89%), blaSHV (82.7%), blaOXA (76.4%), and blaCTX-M-group-1 (72.5%) were most frequent ESBL genes among K. pneumoniae isolates. The blaSHV and blaOXA and blaTEM genotypes were predominantly associated with FOX-CRO-FEP-MEM and CRO-FEP multidrug resistance (MDR) and CRO antimicrobial resistance (AMR) phenotypes, among E. coli isolates from Embu Level V (16.7%) and Kenyatta National Hospital (7.0%), respectively.

Conclusions

The high proportion of ESBL-producing E. coli and K. pneumoniae isolates increases the utilization of last-resort antibiotics, jeopardizing antimicrobial chemotherapy. Furthermore, the antimicrobial resistance patterns exhibited towards extended-spectrum cephalosporins, beta-lactam/beta-lactamase inhibitor combinations, fluoroquinolones, and macrolides show the risk of co-resistance associated with ESBL-producing isolates responsible for MDR. Hence, there is a need for regular surveillance and implementation of infection prevention and control strategies and antimicrobial stewardship programs.

Contribution of genetic factors towards cefotaxime and ciprofloxacin resistance development among Extended spectrum beta-lactamase producing-Quinolone resistant pathogenic Enterobacteriaceae

β-lactams and quinolones are widely utilised to treat pathogenic Enterobacterial isolates worldwide. Due to improper use of these antibiotics, both ESBL producing and quinolone resistant (ESBL-QR) pathogenic bacteria have emerged. Nature of contribution of beta-lactamase (bla)/quinolone resistant (QR) genes, efflux pumps (AcrAB-TolC) over-expression and outer membrane proteins (OMPs) /porin loss/reduction and their combinations towards development of this phenotype were explored in this study. Kirby-Bauer disc diffusion method was used for phenotypic characterization of these bacteria and minimum inhibitory concentration of cefotaxime and ciprofloxacin was determined by broth micro dilution assay. Presence of bla, QR, gyrA/B genes was examined by PCR; acrB upregulation by real-time quantitative PCR and porin loss/reduction by SDS-PAGE. Based on antibiogram, phenotypic categorization of 715 non-duplicate clinical isolates was: ESBL+QR+ (n = 265), ESBL+QR- (n = 6), ESBL-QR+ (n = 346) and ESBL-QR-(n = 11). Increased OmpF/K35 and OmpC/K36 reduction, acrB up-regulation, prevalence of bla, QR genes and gyrA/B mutation was observed among the groups in following order: ESBL+QR+> ESBL-QR+> ESBL+QR-> ESBL-QR-. Presence of bla gene alone or combined porin loss and efflux pump upregulation or their combination contributed most for development of a highest level of cefotaxime resistance of ESBL+QR+ isolates. Similarly, combined presence of QR genes, porin loss/reduction, efflux pump upregulation and gyrA/B mutation contributed towards highest ciprofloxacin resistance development of these isolates.

An insights into emerging trends to control the threats of antimicrobial resistance (AMR): an address to public health risks

Antimicrobial agents are used to treat microbial ailments, but increased use of antibiotics and exposure to infections in healthcare facilities and hospitals as well as the excessive and inappropriate use of antibiotics at the society level lead to the emergence of multidrug-resistant (MDR) bacteria. Antimicrobial resistance (AMR) is considered a public health concern and has rendered the treatment of different infections more challenging. The bacterial strains develop resistance against antimicrobial agents by limiting intracellular drug accumulation (increasing efflux or decreasing influx of antibiotics), modification and inactivation of drugs and its targets, enzymatic inhibition, and biofilm formation. However, the driving factors of AMR include the sociocultural and economic circumstances of a country, the use of falsified and substandard medicines, the use of antibiotics in farm animals, and food processing technologies. These factors make AMR one of the major menaces faced by mankind. In order to promote reciprocal learning, this article summarizes the current AMR situation in Pakistan and how it interacts with the health issues related to the COVID-19 pandemic. The COVID-19 pandemic aids in illuminating the possible long-term impacts of AMR, which are less immediate but not less severe since their measures and effects are equivalent. Impact on other sectors, including the health industry, the economy, and trade are also discussed. We conclude by summarizing the several approaches that could be used to address this issue.

High Genetic Diversity in Third-Generation Cephalosporin-Resistant Escherichia coli in Wastewater Systems of Schleswig-Holstein

The spread of multidrug-resistant bacteria from humans or livestock is a critical issue. However, the epidemiology of resistant pathogens across wastewater pathways is poorly understood. Therefore, we performed a detailed comparison of third-generation cephalosporin-resistant Escherichia coli (3GCREC) from wastewater treatment plants (WWTPs) to analyze dissemination pathways. A total of 172 3GCREC isolated from four WWTPs were characterized via whole genome sequencing. Clonal relatedness was determined using multi-locus sequence typing (MLST) and core genome MLST. Resistance genotypes and plasmid replicons were determined. A total of 68 MLST sequence types were observed with 28 closely related clusters. Resistance genes to eight antibiotic classes were detected. In fluoroquinolone-resistant isolates, resistance was associated with three-or-more point mutations in target genes. Typing revealed high genetic diversity with only a few clonal lineages present in all WWTPs. The distribution paths of individual lines could only be traced in exceptional cases with a lack of enrichment of certain lineages. Varying resistance genes and plasmids, as well as fluoroquinolone resistance-associated point mutations in individual isolates, further corroborated the high diversity of 3GCREC in WWTPs. In total, we observed high diversity of 3GCREC inside the tested WWTPs with proof of resistant strains being released into the environment even after treatment processes.

Phenotypic Detection of Carbapenemase and AmpC-β-Lactamase Production among Extended Spectrum β-Lactamase (ESBL)-Producing Escherichia coli and Klebsiella spp. Isolated from Clinical Specimens

Introduction: Data on antimicrobial resistance (AMR) are sparse across numerous African countries, as microbiological analyses are not routinely conducted and surveillance data are not collected. Accordingly, clinical samples are not routinely tested for carbapenem-resistant bacteria and, therefore, the general understanding of their prevalence in the region remains limited. Methods: Between January 2020 and June 2022, we collected extended spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-PE) isolates from five hospitals in Burkina Faso. After an initial culture on ESBL-selective media, the species were identified using API20E and isolates were tested against 13 antimicrobial agents using the disc diffusion method on Mueller-Hinton (MH) agar. ESBL production was confirmed via a double-disc synergy test. Production of carbapenemases and AmpC-β-lactamases and phenotypic co-resistance were determined. Results: Among the 473 ESBL-PE, 356 were ESBL-E. coli (ESBL-Ec) and 117 were Klebsiella spp. (ESBL-K). Of these isolates, 5.3% were carbapenemase and 5.3% were AmpC-β-lactamase-positive. Three types of carbapenemases were identified: 19 NDM, 3 OXA-48-like and 1 VIM. Two isolates produced both NDM and OXA-48-like carbapenemases. Carbapenemase producers were detected at all levels of healthcare. Co-resistance rates were up to 85% for aminoglycosides, 90% for sulfonamides, 95% for fluoroquinolones and 25% for chloramphenicol. Fosfomycin resistance was 6% for ESBL-Ec and 49% for ESBL-K (49%). Conclusions: Some of the ESBL-Ec and ESBL-K co-produced carbapenemases and/or AmpC-β-lactamases at all healthcare levels and in various sample types with high co-resistance rates to non-betalactams. Carbapenem resistance is no longer rare, calling for testing in routine diagnostics, a comprehensive resistance surveillance system and infection control within healthcare.

Klebsiella pneumoniae clinical isolates with features of both multidrug-resistance and hypervirulence have unexpectedly low virulence

Klebsiella pneumoniae has been classified into two types, classical K. pneumoniae (cKP) and hypervirulent K. pneumoniae (hvKP). cKP isolates are highly diverse and important causes of nosocomial infections; they include globally disseminated antibiotic-resistant clones. hvKP isolates are sensitive to most antibiotics but are highly virulent, causing community-acquired infections in healthy individuals. The virulence phenotype of hvKP is associated with pathogenicity loci responsible for siderophore and hypermucoid capsule production. Recently, convergent strains of K. pneumoniae, which possess features of both cKP and hvKP, have emerged and are cause of much concern. Here, we screen the genomes of 2,608 multidrug-resistant K. pneumoniae isolates from the United States and identify 47 convergent isolates. We perform phenotypic and genomic characterization of 12 representative isolates. These 12 convergent isolates contain a variety of antimicrobial resistance plasmids and virulence plasmids. Most convergent isolates contain aerobactin biosynthesis genes and produce more siderophores than cKP isolates but not more capsule. Unexpectedly, only 1 of the 12 tested convergent isolates has a level of virulence consistent with hvKP isolates in a murine pneumonia model. These findings suggest that additional studies should be performed to clarify whether convergent strains are indeed more virulent than cKP in mouse and human infections.

Current status of β-lactam antibiotic use and characterization of β-lactam-resistant Escherichia coli from commercial farms by integrated broiler chicken operations in Korea

β-Lactam antibiotics are one of the most clinical importance in human and veterinary medicine because they are used for both preventive and therapeutic purposes against several gram-positive, gram-negative, and anaerobic organisms. In this study, it was confirmed that β-lactams (81.1%) were found to be significantly prescribed the most among 74 farms in 5 integrated broiler operations, and single prescription (84.6%), 2-day (41.5%) or 3-day (40.0%) administration, and 15 to 22 d of age (67.7%) administration was significantly higher in the farms (P < 0.05). Among the E. coli isolated from 74 farms in 5 integrated broiler operations, β-lactam-resistant E. coli isolates were detected more frequently in fecal sample (94.6%) than in dust sample (60.8%) (P < 0.05). The prevalence of MDR in β-lactam-resistant isolates, ranging from 88.1 to 96.5%, was significantly higher than that in non-β-lactam-resistant isolates (P < 0.05), without significant differences among operations. Of 466 β-lactam-resistant isolates, 432 (92.7%) isolates harbored β-lactamase genes. The non-extended-spectrum β-lactamase (ESBL) gene blaTEM-1 (81.8%) showed the highest prevalence among isolates, followed by the non-ESBL gene blaTEM-135 (6.4%) (P < 0.05). Five ESBL genes, SHV-12, OXA-1, CTX-M-27, CTX-M-55, and CTX-M-65, were found in 0.9 to 6.0% of the isolates. The pAmpC gene blaCMY-2 was detected in 17 isolates (3.6%). These results suggest that feces and dust are important reservoirs of antimicrobial-resistant bacteria, highlighting the need to strengthen farm management regulations, such as cleaning, disinfection, and litter disposal and to reduce the use of antibiotics in broiler operations.

Occurrence of extended-spectrum β-lactamase-producing Enterobacteriaceae in raw milk from cows with subclinical mastitis in northeast Brazil

Extended-spectrum β-lactamase (ESBL)-producing Gram negative bacteria are becoming increasingly important in veterinary and human medicine because they can hydrolyze the third generation β-lactams, penicillins, and monobactams. The aim of this study was to identify ESBL-producing Enterobacteriaceae in raw cow milk samples from northeast Brazil. Twenty-six bacterial isolates belonging to the Enterobacteriaceae family were obtained from milk samples from 257 cows with subclinical mastitis. Using microbiological tests, 53.85% (14/26) were identified as Escherichia coli, 15.38% (4/26) as Proteus mirabilis, 26.92% (7/26) as Klebsiella spp., and 3.85% (1/26) as Citrobacter spp. Of all the isolates, 61.54% (16/26) were positive in the ESBL screening test, of which 12.5% (2/16) were positive in the double-disc synergy test using three types of cephalosporins and amoxicillin/clavulanic acid. The two isolates were identified as Klebsiella spp. Among all the isolates, 53.85% (14/26) were positive for one or both ESBL-encoding genes, blaSHV and blaTEM; among these, 71.43% (10/14) were identified as E. coli. This study demonstrates that ESBL-producing bacteria can be found in raw cow milk from northeast Brazil. Cows with subclinical mastitis should be recognized as reservoirs of these strains, which can propagate to humans.

Impact of short chain fatty acids (SCFAs) on antimicrobial activity of new β-lactam/β-lactamase inhibitor combinations and on virulence of Escherichia coli isolates

In a healthy gut microbiota, short chain fatty acids (SCFAs) are produced. The antibacterial action of SCFAs against intestinal pathogens makes them useful for ensuring the safety of food and human health. In this study, we aimed to assess the in vitro inhibitory activity of SCFAs, and to report, for the first time, their impact on the activity of new β-lactam/β-lactamase inhibitor combinations. The minimum inhibitory concentrations of acetic, propionic, and butyric acids were determined against E. coli clinical isolates recovered from gastrointestinal infections. Cefoperazone/sulbactam, ceftazidime/avibactam and cefepime/enmetazobactam are new β-lactam/β-lactamase inhibitor combinations that were studied for their combined therapeutic effects. Also, the effects of pH and concentration of SCFAs were evaluated on in vitro bacterial growth and expression of genes encoding for motility, adhesion, invasion, and biofilm formation. SCFAs were tested at concentrations of 12 mM at pH 7.4 (ileum-conditions), in addition to 60 mM and 123 mM, at pH 6.5 (colon-conditions). The tested SCFAs showed the same MIC (3750 μg ml-1 ≃ 60 mM) against all isolates. Furthermore, the addition of SCFAs to the tested β-lactam/β-lactamase inhibitor combinations greatly restored the susceptibility of the isolates. SCFAs had significant effect on bacterial growth and virulence in a pH and concentration-dependent manner; low ileal concentration potentiated E. coli growth, while higher colonic concentration significantly suppressed growth and down-regulated the expression of virulence genes (fliC, ipaH, FimH, BssS). Therefore, the significant inhibitory effect of colonic SCFAs on β-lactam/β-lactamase inhibitor combinations might lead to the development of promising treatment strategies.

Evolution of Antibiotic Resistance in Escherichia coli and Klebsiella pneumoniae Clinical Isolates in a Multi-Profile Hospital over 5 Years (2017-2021)

In recent years, we have witnessed a growing drug resistance among bacteria, which is associated with the use and availability of an increasing number of broad-spectrum antimicrobial agents, as well as with their irrational and excessive use. The present study aims to analyze changes in the drug resistance of Gram-negative Enterobacterales: Escherichia coli and Klebsiella pneumoniae, isolated from infections in a multi-profile hospital over five years (from 2017 to 2021). Among the practical outcomes of the evaluation of these data will be the possibility of determining changes in susceptibility to the antibiotics used in the hospital. In turn, this will help propose new therapeutic options, especially for empirical therapy that is necessary in severe infections. The analysis of the use of individual groups of antibiotics allowed for identification of the causes of the increasing resistance of Gram-negative bacilli. The highest number of infections whose etiological agent was K. pneumoniae ESBL(+) and E. coli ESBL(+) was observed in 2018. In the analyzed five-year period, the number of multi-resistant (MDR) K. pneumoniae strains increased successively, which seems to be related to the growing use, especially in the pandemic period, of broad-spectrum antibiotics, mainly penicillins with inhibitors, third-generation cephalosporins, and carbapenems.

Antibiotics and Bacterial Resistance-A Short Story of an Endless Arms Race

Despite the undisputed development of medicine, antibiotics still serve as first-choice drugs for patients with infectious disorders. The widespread use of antibiotics results from a wide spectrum of their actions encompassing mechanisms responsible for: the inhibition of bacterial cell wall biosynthesis, the disruption of cell membrane integrity, the suppression of nucleic acids and/or proteins synthesis, as well as disturbances of metabolic processes. However, the widespread availability of antibiotics, accompanied by their overprescription, acts as a double-edged sword, since the overuse and/or misuse of antibiotics leads to a growing number of multidrug-resistant microbes. This, in turn, has recently emerged as a global public health challenge facing both clinicians and their patients. In addition to intrinsic resistance, bacteria can acquire resistance to particular antimicrobial agents through the transfer of genetic material conferring resistance. Amongst the most common bacterial resistance strategies are: drug target site changes, increased cell wall permeability to antibiotics, antibiotic inactivation, and efflux pumps. A better understanding of the interplay between the mechanisms of antibiotic actions and bacterial defense strategies against particular antimicrobial agents is crucial for developing new drugs or drug combinations. Herein, we provide a brief overview of the current nanomedicine-based strategies that aim to improve the efficacy of antibiotics.

β-Lactam potentiators to re-sensitize resistant pathogens: Discovery, development, clinical use and the way forward

β-lactam antibiotics are one of the most widely used and diverse classes of antimicrobial agents for treating both Gram-negative and Gram-positive bacterial infections. The β-lactam antibiotics, which include penicillins, cephalosporins, monobactams and carbapenems, exert their antibacterial activity by inhibiting the bacterial cell wall synthesis and have a global positive impact in treating serious bacterial infections. Today, β-lactam antibiotics are the most frequently prescribed antimicrobial across the globe. However, due to the widespread use and misapplication of β-lactam antibiotics in fields such as human medicine and animal agriculture, resistance to this superlative drug class has emerged in the majority of clinically important bacterial pathogens. This heightened antibiotic resistance prompted researchers to explore novel strategies to restore the activity of β-lactam antibiotics, which led to the discovery of β-lactamase inhibitors (BLIs) and other β-lactam potentiators. Although there are several successful β-lactam-β-lactamase inhibitor combinations in use, the emergence of novel resistance mechanisms and variants of β-lactamases have put the quest of new β-lactam potentiators beyond precedence. This review summarizes the success stories of β-lactamase inhibitors in use, prospective β-lactam potentiators in various phases of clinical trials and the different strategies used to identify novel β-lactam potentiators. Furthermore, this review discusses the various challenges in taking these β-lactam potentiators from bench to bedside and expounds other mechanisms that could be investigated to reduce the global antimicrobial resistance (AMR) burden.

Cefiderocol, a Siderophore Cephalosporin, as a Treatment Option for Infections Caused by Carbapenem-Resistant Enterobacterales

Carbapenem-resistant Enterobacterales (CRE) remain a significant public health threat, and, despite recent approvals, new antibiotics are needed. Severe infections caused by CRE, such as nosocomial pneumonia and bloodstream infections, are associated with a relatively high risk of morbidity and mortality. The recent approval of ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam, plazomicin, eravacycline and cefiderocol has broadened the armamentarium for the treatment of patients with CRE infections. Cefiderocol is a siderophore cephalosporin with overall potent in vitro activity against CRE. It is taken up via iron transport channels through active transport, with some entry into bacteria through traditional porin channels. Cefiderocol is relatively stable against hydrolysis by most serine- and metallo-beta-lactamases, including KPC, NDM, VIM, IMP and OXA carbapenemases-the most frequent carbapenemases detected in CRE. The efficacy and safety of cefiderocol has been demonstrated in three randomised, prospective, parallel group or controlled clinical studies in patients at risk of being infected by multidrug-resistant or carbapenem-resistant Gram-negative bacteria. This paper reviews the in vitro activity, emergence of resistance, preclinical effectiveness, and clinical experience for cefiderocol, and its role in the management of patients with CRE infections.

Knockout of Targeted Plasmid-Borne β-Lactamase Genes in an Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strain: Impact on Resistance and Proteomic Profile

Resistance to β-lactams is known to be multifactorial, although the underlying mechanisms are not well established. The aim of our study was to develop a system for assessing the phenotypic and proteomic responses of bacteria to antibiotic stress as a result of the loss of selected antimicrobial resistance genes. We applied homologous recombination to knock out plasmid-borne β-lactamase genes (blaOXA-1, blaTEM-1, and blaCTX-M15) in Escherichia coli CCUG 73778, generating knockout clone variants lacking the respective deleted β-lactamases. Quantitative proteomic analyses were performed on the knockout variants and the wild-type strain, using bottom-up liquid chromatography tandem mass spectrometry (LC-MS/MS), after exposure to different concentrations of cefadroxil. Loss of the blaCTX-M-15 gene had the greatest impact on the resulting protein expression dynamics, while losses of blaOXA-1 and blaTEM-1 affected fewer proteins' expression levels. Proteins involved in antibiotic resistance, cell membrane integrity, stress, and gene expression and unknown function proteins exhibited differential expression. The present study provides a framework for studying protein expression in response to antibiotic exposure and identifying the genomic, proteomic, and phenotypic impacts of resistance gene loss. IMPORTANCE The critical situation regarding antibiotic resistance requires a more in-depth effort for understanding underlying mechanisms involved in antibiotic resistance, beyond just detecting resistance genes. The methodology presented in this work provides a framework for knocking out selected resistance factors, to study the adjustments of the bacterium in response to a particular antibiotic stress, elucidating the genetic response and proteins that are mobilized. The protocol uses MS-based determination of the proteins that are expressed in response to an antibiotic, enabling the selection of strong candidates representing putative resistance factors or mechanisms and providing a basis for future studies to understand their implications in antibiotic resistance. This allows us to better understand how the cell responds to the presence of the antibiotic when a specific gene is lost and, consequently, identify alternative targets for possible future treatment development.

Antibiotic-Loaded Gold Nanoparticles: A Nano-Arsenal against ESBL Producer-Resistant Pathogens

The advent of new antibiotics has helped clinicians to control severe bacterial infections. Despite this, inappropriate and redundant use of antibiotics, inadequate diagnosis, and smart resistant mechanisms developed by pathogens sometimes lead to the failure of treatment strategies. The genotypic analysis of clinical samples revealed that the rapid spread of extended-spectrum β-lactamases (ESBLs) genes is one of the most common approaches acquired by bacterial pathogens to become resistant. The scenario compelled the researchers to prioritize the design and development of novel and effective therapeutic options. Nanotechnology has emerged as a plausible groundbreaking tool against resistant infectious pathogens. Numerous reports suggested that inorganic nanomaterials, specifically gold nanoparticles (AuNPs), have converted unresponsive antibiotics into potent ones against multi-drug resistant pathogenic strains. Interestingly, after almost two decades of exhaustive preclinical evaluations, AuNPs are gradually progressively moving ahead toward clinical evaluations. However, the mechanistic aspects of the antibacterial action of AuNPs remain an unsolved puzzle for the scientific fraternity. Thus, the review covers state-of-the-art investigations pertaining to the efficacy of AuNPs as a tool to overcome ESBLs acquired resistance, their applicability and toxicity perspectives, and the revelation of the most appropriate proposed mechanism of action. Conclusively, the trend suggested that antibiotic-loaded AuNPs could be developed into a promising interventional strategy to limit and overcome the concerns of antibiotic-resistance.

Resistance to Some New Drugs and Prevalence of ESBL- and MBL-Producing Enterobacteriaceae Uropathogens Isolated from Diabetic Patients

Diabetes is a leading non-communicable disease and a risk factor for relapsing infections. The current study was aimed at investigating the prevalence and antibiotic susceptibility of carbapenem-resistant (CR) uropathogens of the family Enterobacteriaceae in diabetic patients. The data of 910 bacterial isolates was collected from diagnostic laboratories during January 2018 to December 2018. The bacterial isolates were identified using traditional methods including colonial characteristics, biochemical tests, and API (20E). Antimicrobial susceptibility and phenotypic characterization of ESBL, MBLs, and KPC was determined by utilizing CLSI recommended methods. The phenotypically positive isolates were further analyzed for resistance-encoding genes by manual PCR and Check-MDR CT103XL microarray. Susceptibility to colistin and cefiderocol was tested in accordance with CLSI guidelines. The data revealed that most of the patients were suffering from type 2 diabetes for a duration of more than a year and with uncontrolled blood sugar levels. Escherichia coli and Klebsiella pneumoniae were the most frequently encountered pathogens, followed by Enterobacter cloacae and Proteus mirabilis. More than 50% of the isolates showed resistance to 22 antibiotics, with the highest resistance (>80%) against tetracycline, ampicillin, and cefazolin. The uropathogens showed less resistance to non-β-lactam antibiotics, including amikacin, fosfomycin, and nitrofurantoin. In the phenotypic assays, 495 (54.3%) isolates were found to be ESBL producers, while ESBL-TEM and -PER were the most prevalent ESBL types. The resistance to carbapenems was slightly less (250; 27.5%) than ESBL producers, yet more common amongst E. coli isolates. MBL production was a common feature in carbapenem-resistant isolates (71.2%); genotypic characterization also validated this trend. The isolates were found to be sensitive against the new drugs, cefiderocol and eravacycline. with 7−28% resistance, except for P. mirabilis which had 100% resistance against eravacycline. This study concludes that a few types of ESBL and carbapenemases are common in the uropathogens isolated from the diabetic patients, and antibiotic stewardship programs need to be revisited, particularly to cure UTIs in diabetic patients.

Human Cell-Camouflaged Nanomagnetic Scavengers Restore Immune Homeostasis in a Rodent Model with Bacteremia

Bloodstream infection caused by antimicrobial resistance pathogens is a global concern because it is difficult to treat with conventional therapy. Here, scavenger magnetic nanoparticles enveloped by nanovesicles derived from blood cells (MNVs) are reported, which magnetically eradicate an extreme range of pathogens in an extracorporeal circuit. It is quantitatively revealed that glycophorin A and complement receptor (CR) 1 on red blood cell (RBC)-MNVs predominantly capture human fecal bacteria, carbapenem-resistant (CR) Escherichia  coli, and extended-spectrum beta-lactamases-positive (ESBL-positive) E. coli, vancomycin-intermediate Staphylococcus aureus (VISA), endotoxins, and proinflammatory cytokines in human blood. Additionally, CR3 and CR1 on white blood cell-MNVs mainly contribute to depleting the virus envelope proteins of Zika, SARS-CoV-2, and their variants in human blood. Supplementing opsonins into the blood significantly augments the pathogen removal efficiency due to its combinatorial interactions between pathogens and CR1 and CR3 on MNVs. The extracorporeal blood cleansing enables full recovery of lethally infected rodent animals within 7 days by treating them twice in series. It is also validated that parameters reflecting immune homeostasis, such as blood cell counts, cytokine levels, and transcriptomics changes, are restored in blood of the fatally infected rats after treatment.

Prevalence of Extended-Spectrum Beta Lactamase-Producing Microorganisms in Dr. Mohammad Hoesin Hospital Palembang

Production of Extended-Spectrum Beta-Lactamase (ESBL) by Enterobacteriaceae continues to be a problem of infectious diseases, especially in hospitals. The main causes of ESBL-producing bacteria colonization are urinary tract infections, length of hospital stay, invasive medical equipment, and antibiotics usage. This study aims to compare the incidence of ESBL based on the type of organism in Dr. Mohammad Hoesin Hospital for the 2017 and 2018 periods. The research design used was descriptive with a cross-sectional approach, which used secondary data at the Clinical Pathology Department of Dr. RSUP. Mohammad Hoesin Palembang. The findings of this study showed a decreasing pattern in the incidence of ESBL in 2017 and 2018, but with a similar pattern which was dominated by Klebsiella pneumoniae (followed by Escherichia coli and Klebsiella ozaenae), inpatients in pediatric wards, internal medicine, and intensive care units, and on sputum specimens. This study showed the presence of high levels of ESBL-producing bacteria (>60%) in Dr. Mohammad Hoesin Hospital, which was mainly caused by Klebsiella pneumoniae.

A review of horses as a source of spreading livestock-associated methicillin-resistant Staphylococcus aureus to human health

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) was first discovered in horses in 1989. Since then, LA-MRSA has begun to be considered an important strain of pathogenic bacteria in horses, which can cause LA-MRSA infection and colonization in humans with public health impacts. The anterior nares are the primary site of LA-MRSA colonization in horses, although LA-MRSA colonization may also occur in the gastrointestinal tract in horses. LA-MRSA-infected horses typically exhibit clinical infection or may not exhibit clinical infection. There are two potential risks associated with LA-MRSA colonization in horses: The possibility of disease development in horses infected with LA-MRSA and the possibility of LA-MRSA transfer to humans and other horses. The diagnosis of LA-MRSA in horses can be made by conducting in vitro sensitivity testing for oxacillin and cefoxitin, and then followed by a molecular test using polymerase chain reaction. LA-MRSA transmission in animal hospitals and on farms is most likely due to contact with horses infected or colonized by LA-MRSA. The history of prior antibiotic administration, history of prior LA-MRSA colonization, and length of equine hospitalization were described as risk factors in cases of infection and colonization of LA-MRSA in horses. Nebulized antibiotics may be a viable alternative to use in horses, but nebulized antibiotics are only used in horses that are persistently colonized with LA-MRSA. Controlling the spread of LA-MRSA in horses can be done by regularly washing horses, eradicating vectors in horse stalls such as rats, and maintaining the cleanliness of the stable and animal hospital environment. Meanwhile, cleaning hands, using gloves, and donning protective clothes are ways that humans can prevent the transmission of LA-MRSA when handling horses. This review will explain the definition of LA-MRSA in general, LA-MRSA in horses, the epi­demiology of LA-MRSA in horses, the diagnosis of LA-MRSA in horses, the transmission of LA-MRSA in horses, risk factors for spreading LA-MRSA in horses, public health impact, treatment of LA-MRSA infection in horses, and control of the spread of LA-MRSA in horses.

Characterization of Beta-Lactam Resistance Genes and Virulence Factors Associated with Multidrug-Resistant Klebsiella pneumoniae Isolated from Patients at Major Hospitals in Trinidad, West Indies

Accurate species identification and antibiotic resistance profiling are essential for the effective management of infections caused by bacterial pathogens. In this study, 373 clinical isolates of K. pneumoniae from major hospitals in Trinidad, West Indies, were characterized for resistance against beta-lactam antibiotics and the presence of genes encoding important virulence factors. Most of the isolates showed extended spectrum β-lactamase (ESBL) activity but few also displayed carbapenemase or 'ESBL + carbapenemase' activities. Polymerase chain reaction analysis revealed the presence of genes for ESBL subtypes bla_TEM, bla_SHV, and bla_CTX-M that were dominant in isolates with the ESBL phenotype as well as those that did not show ESBL or carbapenemase activities. The carbapenem resistance gene, bla_KPC, and the metallo-β-lactamase (MBL) gene, bla_NDM-1, were also detected in some of the isolates. Multiple virulence genes were also detected, but the fimH-uge was the most common combination found among the local isolates. The findings of this study represent the first comprehensive study on the prevalence of ESBL, KPC and MBL genes and virulence profiling in antibiotic-resistant K. pneumoniae in Trinidad. Furthermore, the occurrence of multiple resistant phenotypes and gene combinations were revealed, though at low prevalence rates. This work emphasizes the need to implement molecular-based techniques in diagnostic workflows for rapid and accurate species identification and profiling of resistance and virulence genes in K. pneumoniae in Trinidad and Tobago.

Antibacterial Mechanisms of Zinc Oxide Nanoparticle against Bacterial Food Pathogens Resistant to Beta-Lactam Antibiotics

The increase in β-lactam-resistant Gram-negative bacteria is a severe recurrent problem in the food industry for both producers and consumers. The development of nanotechnology and nanomaterial applications has transformed many features in food science. The antibacterial activity of zinc oxide nanoparticles (ZnO NPs) and their mechanism of action on β-lactam-resistant Gram-negative food pathogens, such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Klebsiella pneumoniae, and Proteus mirabilis, are investigated in the present paper. The study results demonstrate that ZnO NPs possesses broad-spectrum action against these β-lactamase-producing strains. The minimal inhibitory and minimal bactericidal concentrations vary from 0.04 to 0.08 and 0.12 to 0.24 mg/mL, respectively. The ZnO NPs elevate the level of reactive oxygen species (ROS) and malondialdehyde in the bacterial cells as membrane lipid peroxidation. It has been confirmed from the transmission electron microscopy image of the treated bacterial cells that ZnO NPs diminish the permeable membrane, denature the intracellular proteins, cause DNA damage, and cause membrane leakage. Based on these findings, the action of ZnO NPs has been attributed to the fact that broad-spectrum antibacterial action against β-lactam-resistant Gram-negative food pathogens is mediated by Zn2+ ion-induced oxidative stress, actions via lipid peroxidation and membrane damage, subsequently resulting in depletion, leading to β-lactamase enzyme inhibition, intracellular protein inactivation, DNA damage, and eventually cell death. Based on the findings of the present study, ZnO NPs can be recommended as potent broad-spectrum antibacterial agents against β-lactam-resistant Gram-negative pathogenic strains.

Effect of Essential Oils Supplemented with Caprylic Acid and Sodium Chloride against Faecal ESBL-Producing Escherichia coli Isolated from Pigs

The purpose of the present investigation was to compare the antibacterial activity of six commercial and lab-scale extracted essential oils (EOs) alone or in combination with caprylic acid (CA) and sodium chloride (NaCl) against faecal Escherichia coli with and without extended-spectrum beta-lactamase (ESBL) encoding genes, and of isolates classified as multidrug-resistant (MDR). Gas chromatography−mass spectrometry (GC−MS) was used for the analysis of chemical composition of EOs, while the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were carried out to elucidate the antibacterial activity of non-supplemented and supplemented EOs against different resistance levels of E. coli strains. The main compounds in commercial EOs were aromatic monoterpenoids (30−56%) and p-cymene (8−35%), while the main compounds in the lab-scale EOs were aromatic monoterpenoids (12−37%) and γ-terpinene (18−22%). Commercial EOs exhibited superior inhibitory activity of E. coli in comparison to lab-scale produced EOs. Antibacterial activity of EOs was significantly enhanced by enrichment of the EOs with NaCl (p < 0.001) or CA (p = 0.012). Most of the non-supplemented EOs exhibited lower activity against MDR and ESBL producing E. coli. In contrast, EOs supplemented with CA and especially NaCl was equally effective against ESBL and non-ESBL as well as MDR and non-MDR E. coli. It was found that supplementation of EOs with NaCl could enhance the antibacterial activity towards ESBL and MDR E. coli isolates. However, additional studies are needed to clarify the potential risks of developing resistance.

Antimicrobial Peptides: From Design to Clinical Application

Infection of multidrug-resistant (MDR) bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae (CRE), and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, brings public health issues and causes economic burden. Pathogenic bacteria develop several methods to resist antibiotic killing or inhibition, such as mutation of antibiotic function sites, activation of drug efflux pumps, and enzyme-mediated drug degradation. Antibiotic resistance components can be transferred between bacteria by mobile genetic elements including plasmids, transposons, and integrons, as well as bacteriophages. The development of antibiotic resistance limits the treatment options for bacterial infection, especially for MDR bacteria. Therefore, novel or alternative antibacterial agents are urgently needed. Antimicrobial peptides (AMPs) display multiple killing mechanisms against bacterial infections, including directly bactericidal activity and immunomodulatory function, as potential alternatives to antibiotics. In this review, the development of antibiotic resistance, the killing mechanisms of AMPs, and especially, the design, optimization, and delivery of AMPs are reviewed. Strategies such as structural change, amino acid substitution, conjugation with cell-penetration peptide, terminal acetylation and amidation, and encapsulation with nanoparticles will improve the antimicrobial efficacy, reduce toxicity, and accomplish local delivery of AMPs. In addition, clinical trials in AMP studies or applications of AMPs within the last five years were summarized. Overall, AMPs display diverse mechanisms of action against infection of pathogenic bacteria, and future research studies and clinical investigations will accelerate AMP application.

Proteomics in antibiotic resistance and tolerance research: Mapping the resistome and the tolerome of bacterial pathogens

Antibiotic resistance, the ability of a microbial pathogen to evade the effects of antibiotics thereby allowing them to grow under elevated drug concentrations, is an alarming health problem worldwide and has attracted the attention of scientists for decades. On the other hand, the clinical importance of persistence and tolerance as alternative mechanisms for pathogens to survive prolonged lethal antibiotic doses has recently become increasingly appreciated. Persisters and high-tolerance populations are thought to cause the relapse of infectious diseases, and provide opportunities for the pathogens to evolve resistance during the course of antibiotic therapy. Although proteomics and other omics methodology have long been employed to study resistance, its applications in studying persistence and tolerance are still limited. However, due to the growing interest in the topic and recent progress in method developments to study them, there have been some proteomic studies that yield fresh insights into the phenomenon of persistence and tolerance. Combined with the studies on resistance, these collectively guide us to novel molecular targets for the potential drugs for the control of these dangerous pathogens. In this review, we surveyed previous proteomic studies to investigate resistance, persistence, and tolerance mechanisms, and discussed emerging experimental strategies for studying these phenotypes with a combination of adaptive laboratory evolution and high-throughput proteomics. This article is protected by copyright. All rights reserved.