Plasmid mediated colistin resistant mcr-1 and co-existence of OXA-48 among Escherichia coli from clinical and poultry isolates: first report from Nepal

Protective effects of antibiotic resistant bacteria on susceptibles in biofilm: Influential factors, mechanism, and modeling

In environmental biofilms, antibiotic-resistant bacteria facilitate the persistence of susceptible counterparts under antibiotic stresses, contributing to increased community-level resistance. However, there is a lack of quantitative understanding of this protective effect and its influential factors, hindering accurate risk assessment of biofilm resistance in diverse environment. This study isolated an opportunistic Escherichia coli pathogen from soil, and engineered it with plasmids conferring antibiotic resistance. Protective effects of the ampicillin resistant strain (AmpR) on their susceptible counterparts (AmpS) were observed in ampicillin-stress colony biofilms. The concentration of ampicillin delineated protective effects into 3 zones: continuous protection (<1 MIC of AmpS), initial AmpS/R dependent (1-8 MIC of AmpS), and ineffective (>8 MIC of AmpS). Intriguingly, Zone 2 exhibited a surprising "less is more" phenomenon tuned by the initial AmpS/R ratio, where biofilm with an initially lower AmpR (1:50 vs 50:1) harbored 30-90 % more AmpR after 24 h growth under antibiotic stress. Compared to AmpS, AmpR displayed superiority in adhesion, antibiotic degradation, motility, and quorum sensing, allowing them to preferentially colonize biofilm edge and areas with higher ampicillin. An agent-based model incorporating protective effects successfully simulated tempo-spatial dynamics of AmpR and AmpS influenced by antibiotic stress and initial AmpS/R. This study provides a holistic view on the pervasive but poorly understood protective effects in biofilm, enabling development of better risk assessment and precisely targeted control strategies of biofilm resistance in diverse environment.

Multidrug resistance plasmids commonly reprogram the expression of metabolic genes in Escherichia coli

Multidrug-resistant Escherichia coli is a leading cause of global mortality. Transfer of plasmids carrying genes encoding beta-lactamases, carbapenamases, and colistin resistance between lineages is driving the rising rates of hard-to-treat nosocomial and community infections. Multidrug resistance (MDR) plasmid acquisition commonly causes transcriptional disruption, and while a number of studies have shown strain-specific fitness and transcriptional effects of an MDR plasmid across diverse bacterial lineages, fewer studies have compared the impacts of different MDR plasmids in a common bacterial host. As such, our ability to predict which MDR plasmids are the most likely to be maintained and spread in bacterial populations is limited. Here, we introduced eight diverse MDR plasmids encoding resistances against a range of clinically important antibiotics into E. coli K-12 MG1655 and measured their fitness costs and transcriptional impacts. The scale of the transcriptional responses varied substantially between plasmids, ranging from >650 to <20 chromosomal genes being differentially expressed. However, the scale of regulatory disruption did not correlate significantly with the magnitude of the plasmid fitness cost, which also varied between plasmids. The identities of differentially expressed genes differed between transconjugants, although the expression of certain metabolic genes and functions were convergently affected by multiple plasmids, including the downregulation of genes involved in L-methionine transport and metabolism. Our data show the complexity of the interaction between host genetic background and plasmid genetic background in determining the impact of MDR plasmid acquisition on E. coli.

IMPORTANCE

The increase in infections that are resistant to multiple classes of antibiotics, including those isolates that carry carbapenamases, beta-lactamases, and colistin resistance genes, is of global concern. Many of these resistances are spread by conjugative plasmids. Understanding more about how an isolate responds to an incoming plasmid that encodes antibiotic resistance will provide information that could be used to predict the emergence of MDR lineages. Here, the identification of metabolic networks as being particularly sensitive to incoming plasmids suggests the possible targets for reducing plasmid transfer.

Antibiotic resistance determinants among carbapenemase producing bacteria isolated from wastewaters of Kathmandu, Nepal

The emergence of carbapenem resistant bacteria (CRB) possesses a remarkable threat to the health of humans. CRB and carbapenem resistance genes (CRGs) have frequently been reported in clinical isolates from hospitals, however, their occurrence and distribution in wastewaters from various sources and river water have not been emphasized in Nepal. So, this study aimed to detect carbapenem resistant bacterial isolates and their resistance determinants in river water and different types of wastewaters. River water and both untreated and treated wastewater samples from hospitals, pharmaceutical industries, and municipal sewage were collected in summer and winter seasons. From 68 grab wastewater samples, CRB were detected only in 16 samples, which included eight hospital wastewater, and four each from untreated municipal sewage and river water. A total of 25 CRB isolates were detected with dominance of E. coli (44.0%) and K. pneumoniae (24.0%). The majority of the isolates harbored blaNDM-1 (76.0%), followed by blaOXA (36.0%) and blaKPC (20.0%) genes. Hospital wastewater majorly contributed to the presence of blaNDM-1, blaKPC, and blaOXA along with intI1 genes compared to river water and untreated municipal sewage, especially during the winter season. However, CRB were not detected in treated effluents of hospitals and municipal sewage, and both influents and effluents from pharmaceutical industries. The combined presence of each blaNDM-1 & blaOXA and blaKPC & blaOXA occurred in 16.0% of the bacterial isolates. The increased minimum inhibitory concentration (MIC) of meropenem was significantly associated with the presence of CRGs. The results of this study highlight the significance of carbapenem resistance in bacteria isolated from wastewater and river water, and underscore the necessity for efficient monitoring and control strategies to prevent the dispersion of carbapenem resistance in the environment and its potential consequences on human health.

Inactivation of MST1/2 Controls Macrophage Polarization to Affect Macrophage-Related Disease via YAP and Non-YAP Mechanisms

Macrophage polarization is a critical process that regulates in inflammation, pathogen defense, and tissue repair. Here we demonstrate that MST1/2, a core kinase of Hippo pathway and a recently identified regulator of inflammation, plays a significant role in promoting M2 polarization. We provide evidence that inhibition of MST1/2, achieved through either gene-knockout or pharmacological treatment, leads to increased M1 polarization in a YAP-dependent manner, resulting in the development of M1-associated inflammatory disorders. Moreover, MST1/2 inhibition also leads to a substantial reduction in M2 polarization, but this occurs through the STAT6 and MEK/ERK signaling. The STAT6 is independent of YAP, but MEK/ERK is dependent of YAP. Consistent with these observations, both MST1/2-conditional knockout mice and wild-type mice treated with XMU-MP-1, a chemical inhibitor of MST1/2, exhibited reduced M2-related renal fibrosis, while simultaneously displaying enhanced LPS-mediated inflammation and improved clearance of MCR3-modified gram-negative bacteria. These findings uncover a novel role of MST1/2 in regulating macrophage polarization and establish it as a potential therapeutic target for the treatment of macrophage-related fibrotic diseases.

Prevalence of blaCTX-M and blaTEM Genes in Cefotaxime-Resistant Escherichia coli Recovered from Tertiary Care at Central Nepal: A Descriptive Cross-Sectional Study

Urinary tract infections (UTIs) are highly prevalent globally, and various antibiotics are employed for their treatment. However, the emergence of drug-resistant uropathogens towards these antibiotics causes a high rate of morbidity and mortality. This study was conducted at the Microbiology Laboratory of Grande International Hospital from November 2021 to May 2022 and aimed to assess the prevalence of UTI caused by Escherichia coli and their antibiotic susceptibility pattern with a focus on extended-spectrum beta-lactamases (ESBLs) and the prevalence of two genes (blaCTX-M and blaTEM) in cephalosporin-resistant E. coli. Altogether, 1050 urine samples were processed to obtain 165 isolates of E. coli. The isolates were identified by colony morphology and biochemical characteristics. Antimicrobial susceptibility tests (ASTs) were determined by the Kirby-Bauer disk diffusion method, and their ESBL enzymes were estimated by the combined disk method (CDM). Two ESBL genes (blaCTX-M and blaTEM) were investigated by polymerase chain reaction (PCR) in cefotaxime-resistant E. coli. Among the 1050 urine samples that were processed, 335 (31.9%) were culture-positive with 165 (49.2%) identified as E. coli. The age group ≥60 years (30.3%) had greater susceptibility to bacterial infections. AST revealed that meropenem was highly effective (95.7% susceptibility), while ampicillin showed the least sensitivity (42.4%). Among the E. coli isolates, 86 were multidrug resistant (MDR) and 10 were extensively drug resistant (XDR). Of these, 46 MDR (96%) and 2 XDR (4%) were ESBL producers. The prevalence of ESBL genes (blaCTX-M and blaTEM) was 49.3% and 54.8%, respectively. The overall accuracy of CDM as compared to PCR for the detection of the blaCTX-M gene was 55.26%. The prevalence of MDR E. coli harboring the blaCTX-M and blaTEM genes underscores the imperative role of ESBL testing in accurately identifying both beta-lactamase producers and nonproducers.

Synergistic effects of polymyxin and vancomycin combinations on carbapenem- and polymyxin-resistant Klebsiella pneumoniae and their molecular characteristics

IMPORTANCE

This study provides insights into the mechanisms of polymyxin resistance in K. pneumoniae clinical isolates and demonstrates potential strategies of polymyxin and vancomycin combinations for combating this resistance. We also identified possible mechanisms that might be associated with the treatment of these combinations against carbapenem- and polymyxin-resistant K. pneumoniae clinical isolates. The findings have significant implications for the development of alternative therapies and the effective management of infections caused by these pathogens.

Effect of Zinc Oxide and Copper Sulfate on Antibiotic Resistance Plasmid Transfer in Escherichia coli

Heavy metals such as zinc (Zn) and copper (Cu) may be associated with antibiotic resistance dissemination. Our aim was to investigate whether sub-lethal dosage of Zn and Cu may enhance plasmid transfer and subsequently resistance genes dissemination. Plasmid conjugation frequencies (PCF) were performed with Escherichia coli strains bearing IncL-blaOXA-48, IncA/C-blaCMY-2, IncI1-blaCTX-M-1, IncF-blaCTX-M-1, and IncX3-blaNDM-5 as donors. Mating-out assays were performed with sub-dosages of zinc oxide (ZnO) and Cu sulfate (CuSO4). Quantification of the SOS response-associated gene expression levels and of the production of reactive oxygen species were determined. Increased PCF was observed for IncL, IncA/C, and IncX3 when treated with ZnO. PCF was only increased for IncL when treated with CuSO4. The ROS production presented an overall positive correlation with PCF after treatment with ZnO for IncL, IncA/C, and IncX3. For CuSO4 treatment, the same was observed only for IncL. No increase was observed for expression of SOS response-associated genes under CuSO4 treatment, and under ZnO treatment, we observed an increase in SOS response-associated genes only for IncX3. Our data showed that sub-dosages of ZnO and CuSO4 could significantly enhance PCF in E. coli, with a more marked effect observed with IncL, IncA/C, and IncX3 scaffolds. Our study suggested that use of certain heavy metals is not the panacea for avoiding use of antibiotics in order to prevent the dissemination of antibiotic resistance.

Impact of veterinary antibiotics on plasmid-encoded antibiotic resistance transfer

OBJECTIVES

Resistance genes can be genetically transmitted and exchanged between commensal and pathogenic bacterial species, and in different compartments including the environment, or human and animal guts (One Health concept). The aim of our study was to evaluate whether subdosages of antibiotics administered in veterinary medicine could enhance plasmid transfer and, consequently, resistance gene exchange in gut microbiota.

METHODS

Conjugation frequencies were determined with Escherichia coli strains carrying IncL- (blaOXA-48) or IncI1-type (blaCTX-M-1) plasmids subjected to a series of subinhibitory concentrations of antibiotics used in veterinary medicine, namely amoxicillin, ceftiofur, apramycin, neomycin, enrofloxacin, colistin, erythromycin, florfenicol, lincomycin, oxytetracycline, sulfamethazine, tiamulin and the ionophore narasin. Treatments with subinhibitory dosages were performed with and without supplementation with the antioxidant edaravone, known as a mitigator of the inducibility effect of several antibiotics on plasmid conjugation frequency (PCF). Expression of SOS-response associated genes and fluorescence-based reactive oxygen species (ROS) detection assays were performed to evaluate the stress oxidative response.

RESULTS

Increased PCFs were observed for both strains when treating with florfenicol and oxytetracycline. Increased expression of the SOS-associated recA gene also occurred concomitantly, as well as increased ROS production. Addition of edaravone to the treatments reduced their PCF and also showed a decreasing effect on SOS and ROS responses for both plasmid scaffolds.

CONCLUSIONS

We showed here that some antibiotics used in veterinary medicine may induce transfer of plasmid-encoded resistance and therefore may contribute to the worldwide spread of antibiotic resistance genes.

Uncovering the Resistance Mechanisms in Extended-Drug-Resistant Pseudomonas aeruginosa Clinical Isolates: Insights from Gene Expression and Phenotypic Tests

(1) Background: The purpose of the study was to describe the activity of mex efflux pumps in Multidrug-Resistant (MDR) clinical isolates of Pseudomonas aeruginosa and to compare the carbapenem-resistance identification tests with PCR; (2) Methods: Sixty MDR P. aeruginosa were analyzed for detection of carbapenemase by disk diffusion inhibitory method, carbapenem inactivation method and Modified Hodge Test. Endpoint PCR was used to detect 7 carbapenemase genes (blaKPC, blaOXA48-like, blaNDM, blaGES-2, blaSPM, blaIMP, blaVIM) and mcr-1 for colistin resistance. The expression of mexA, mexB, mexC, mexE and mexX genes corresponding to the four main efflux pumps was also evaluated; (3) Results: From the tested strains, 71.66% presented at least one carbapenemase gene, with blaGES-2 as the most occurring gene (63.3%). Compared with the PCR, the accuracy of phenotypic tests did not exceed 25% for P. aeruginosa. The efflux pump genes were present in all strains except one. In 85% of the isolates, an overactivity of mexA, mexB and mostly mexC was detected. Previous treatment with ceftriaxone increased the activity of mexC by more than 160 times; (4) Conclusions: In our MDR P. aeruginosa clinical isolates, the carbapenem resistance is not accurately detected by phenotypic tests, due to the overexpression of mex efflux pumps and in a lesser amount, due to carbapenemase production.

Carbapenem resistance in the food supply chain

Carbapenems are critically important antibiotic agents because they are considered the "last-resort" antibiotics for treating serious infections. However, resistance to carbapenems is increasing throughout the world and has become an urgent problem. Some carbapenem-resistant bacteria are considered urgent threats by the United States Centers for Disease Control and Prevention. In this review, we searched and summarized studies published mostly in the recent five years related to carbapenem resistance in three main areas in the food supply chain: livestock, aquaculture, and fresh produce. We have found that many studies have shown a direct or indirect correlation between carbapenem resistance in the food supply chain and human infections. Our review also revealed the worrisome incidences of the cooccurrence of resistance to carbapenem and other "last-resort" antibiotics, such as colistin and/or tigecycline, in the food supply chain. Antibiotic resistance is a global public health challenge, and more effort related to carbapenem resistance in the food supply chain for different food commodities is still needed in some countries and regions, including the United States. In addition, antibiotic resistance in the food supply chain is a complicated issue. Based on the knowledge from current studies, only restricting the use of antibiotics in food animal production might not be enough. Additional research is needed to determine factors contributing to the introduction and persistence of carbapenem resistance in the food supply chain. Through this review, we hope to provide a better understanding of the current state of carbapenem resistance, and the niches of knowledge that are needed for developing strategies to mitigate antibiotic resistance, especially carbapenem resistance in the food supply chain.

Mobile Colistin Resistance (mcr) Gene-Containing Organisms in Poultry Sector in Low- and Middle-Income Countries: Epidemiology, Characteristics, and One Health Control Strategies

Mobile colistin resistance (mcr) genes (mcr-1 to mcr-10) are plasmid-encoded genes that threaten the clinical utility of colistin (COL), one of the highest-priority critically important antibiotics (HP-CIAs) used to treat infections caused by multidrug-resistant and extensively drug-resistant bacteria in humans and animals. For more than six decades, COL has been used largely unregulated in the poultry sector in low- and middle-income countries (LMICs), and this has led to the development/spread of mcr gene-containing bacteria (MGCB). The prevalence rates of mcr-positive organisms from the poultry sector in LMICs between January 1970 and May 2023 range between 0.51% and 58.8%. Through horizontal gene transfer, conjugative plasmids possessing insertion sequences (ISs) (especially ISApl1), transposons (predominantly Tn6330), and integrons have enhanced the spread of mcr-1, mcr-2, mcr-3, mcr-4, mcr-5, mcr-7, mcr-8, mcr-9, and mcr-10 in the poultry sector in LMICs. These genes are harboured by Escherichia, Klebsiella, Proteus, Salmonella, Cronobacter, Citrobacter, Enterobacter, Shigella, Providencia, Aeromonas, Raoultella, Pseudomonas, and Acinetobacter species, belonging to diverse clones. The mcr-1, mcr-3, and mcr-10 genes have also been integrated into the chromosomes of these bacteria and are mobilizable by ISs and integrative conjugative elements. These bacteria often coexpress mcr with virulence genes and other genes conferring resistance to HP-CIAs, such as extended-spectrum cephalosporins, carbapenems, fosfomycin, fluoroquinolone, and tigecycline. The transmission routes and dynamics of MGCB from the poultry sector in LMICs within the One Health triad include contact with poultry birds, feed/drinking water, manure, poultry farmers and their farm workwear, farming equipment, the consumption and sale of contaminated poultry meat/egg and associated products, etc. The use of pre/probiotics and other non-antimicrobial alternatives in the raising of birds, the judicious use of non-critically important antibiotics for therapy, the banning of nontherapeutic COL use, improved vaccination, biosecurity, hand hygiene and sanitization, the development of rapid diagnostic test kits, and the intensified surveillance of mcr genes, among others, could effectively control the spread of MGCB from the poultry sector in LMICs.

Antimicrobial Resistance Profiles and Co-Existence of Multiple Antimicrobial Resistance Genes in mcr-Harbouring Colistin-Resistant Enterobacteriaceae Isolates Recovered from Poultry and Poultry Meats in Malaysia

The co-existence of the colistin resistance (mcr) gene with multiple drug-resistance genes has raised concerns about the possibility of the development of pan-drug-resistant bacteria that will complicate treatment. This study aimed to investigate the antibiotic resistance profiles and co-existence of antibiotic resistance genes among the colistin-resistant Enterobacteriaceae isolates recovered from poultry and poultry meats. The antibiotic susceptibility to various classes of antibiotics was performed using the Kirby-Bauer disk diffusion method and selected antimicrobial resistance genes were detected using PCR in a total of 54 colistin-resistant Enterobacteriaceae isolates including Escherichia coli (E. coli) (n = 32), Salmonella spp. (n = 16) and Klebsiella pneumoniae (K. pneumoniae) (n = 6) isolates. Most of the isolates had multi-drug resistance (MDR), with antibiotic resistance against up to seven classes of antibiotics. All mcr-harbouring, colistin-resistant Enterobacteriaceae isolates showed this MDR (100%) phenotype. The mcr-1 harbouring E. coli isolates were co-harbouring multiple antibiotic resistance genes. The seven most commonly identified resistance genes (^blaTEM, tetA, floR, aac-3-IV, aadA1, fosA, aac(6_)-lb) were detected in an mcr-1-harbouring E. coli isolate recovered from a cloacal swab. The mcr-5 harbouring Salmonella spp. isolate recovered from poultry meats was positive for ^blaTEM, tetA, floR, aac-3-IV, fosA and aac(6_)-lb genes. In conclusion, the colistin-resistant Enterobacteriaceae with mcr genes co-existing multiple clinically important antimicrobial resistance genes in poultry and poultry meats may cause potential future threats to infection treatment choices in humans and animals.

Epidemiology and zoonotic transmission of mcr-positive and carbapenemase-producing Enterobacterales on German turkey farms

Introduction

The emergence of carbapenem-resistant bacteria causing serious infections may lead to more frequent use of previously abandoned antibiotics like colistin. However, mobile colistin resistance genes (mcr) can jeopardise its effectiveness in both human and veterinary medicine. In Germany, turkeys have been identified as the food-producing animal most likely to harbour mcr-positive colistin-resistant Enterobacterales (mcr-Col-E). Therefore, the aim of the present study was to assess the prevalence of both mcr-Col-E and carbapenemase-producing Enterobacterales (CPE) in German turkey herds and humans in contact with these herds.

Methods

In 2018 and 2019, 175 environmental (boot swabs of turkey faeces) and 46 human stool samples were analysed using a combination of enrichment-based culture, PCR, core genome multilocus sequence typing (cgMLST) and plasmid typing.

Results

mcr-Col-E were detected in 123 of the 175 turkey farms in this study (70.3%). mcr-Col-E isolates were Escherichia coli (98.4%) and Klebsiella spp. (1.6%). Herds that had been treated with colistin were more likely to harbour mcr-Col-E, with 82.2% compared to 66.2% in untreated herds (p = 0.0298). Prevalence also depended on husbandry, with 7.1% mcr-Col-E in organic farms compared to 74.5% in conventional ones (p < 0.001). In addition, four of the 46 (8.7%) human participants were colonised with mcr-Col-E. mcr-Col-E isolates from stables had minimum inhibitory concentrations (MICs) from 4 to ≥ 32 mg/l, human isolates ranged from 4 to 8 mg/l. cgMLST showed no clonal transmission of isolates. For one farm, plasmid typing revealed great similarities between plasmids from an environmental and a human sample. No CPE were found in turkey herds or humans.

Discussion

These findings confirm that mcr-Col-E-prevalence is high in turkey farms, but no evidence of direct zoonotic transmission of clonal mcr-Col-E strains was found. However, the results indicate that plasmids may be transmitted between E. coli isolates from animals and humans.

Uropathogenic Escherichia coli endeavors: an insight into the characteristic features, resistance mechanism, and treatment choice

Uropathogenic Escherichia coli (UPEC) are the strains diverted from the intestinal status and account mainly for uropathogenicity. This pathotype has gained specifications in structure and virulence to turn into a competent uropathogenic organism. Biofilm formation and antibiotic resistance play an important role in the organism's persistence in the urinary tract. Increased consumption of carbapenem prescribed for multidrug-resistant (MDR) and Extended-spectrum-beta lactamase (ESBL)-producing UPECs, has added to the expansion of resistance. The World Health Organization (WHO) and Centre for Disease Control (CDC) placed the Carbapenem-resistant Enterobacteriaceae (CRE) on their treatment priority lists. Understanding both patterns of pathogenicity, and multiple drug resistance may provide guidance for the rational use of anti-bacterial agents in the clinic. Developing an effective vaccine, adherence-inhibiting compounds, cranberry juice, and probiotics are non-antibiotical approaches proposed for the treatment of drug-resistant UTIs. We aimed to review the distinguishing characteristics, current therapeutic options and promising non-antibiotical approaches against ESBL-producing and CRE UPECs.

The menace of colistin resistance across globe: Obstacles and opportunities in curbing its spread

Colistin-resistance in bacteria is a big concern for public health, since it is a last resort antibiotic to treat infectious diseases of multidrug resistant and carbapenem resistant Gram-negative pathogens in clinical settings. The emergence of colistin resistance in aquaculture and poultry settings has escalated the risks associated with colistin resistance in environment as well. The staggering number of reports pertaining to the rise of colistin resistance in bacteria from clinical and non-clinical settings is disconcerting. The co-existence of colistin resistant genes with other antibiotic resistant genes introduces new challenges in combatting antimicrobial resistance. Some countries have banned the manufacture, sale and distribution of colistin and its formulations for food producing animals. However, to tackle the issue of antimicrobial resistance, a one health approach initiative, inclusive of human, animal, and environmental health needs to be developed. Herein, we review the recent reports in colistin resistance in bacteria of clinical and non-clinical settings, deliberating on the new findings obtained regarding the development of colistin resistance. This review also discusses the initiatives implemented globally in mitigating colistin resistance, their strength and weakness.

Extended-Spectrum Beta-Lactamase and Carbapenem-Resistant Gram-Negative Pathogens in Makkah, Saudi Arabia

Background

This study aimed to determine the prevalence of extended-spectrum-beta-lactamase (ESBL) and carbapenem-resistant gram-negative bacteria (GNB) isolated from patients at the King Faisal Hospital in Makkah, Saudi Arabia.

Methods

In this cross-sectional study, a total of 298 patients admitted to the intensive care unit for 48 hours and who had a central venous catheter were selected using a census sampling method. Only patients with ESBL and carbapenem-resistant GNB-isolated organisms (175 patients) were included. The susceptibility test of GNB was carried out according to the standard recommendations. The identified strains were tested in-vitro against several antimicrobial drugs. Statistical analysis was performed using SPSS version 24.

Results

36(20.6%) of samples were ESBL-producing GNB, whereas 139(79.4%) were carbapenem-resistant GNB. The pooled proportional estimates of ESBL-producing GNB Escherichia coli, Klebsiella pneumoniae, and other GNB were 44.4%, 41.6%, and 14.0%, respectively; the pooled proportional estimates of carbapenem resistance GNB Klebsiella pneumoniae, Acinetobacter baumannii complex/hemolyticus and other GNB were 82.8%, 10.8%, and 6.4%, respectively. All ESBL-producing GNB and carbapenem-resistance GNB were multidrug-resistant pathogens. The highest carbapenem resistance GNB 139(100%) was to ampicillin, and the lowest 122(87.7%) was to Amoxicillin/clavulanic acid (Amox/clav). All ESBL-producing GNB 36 (100%) were resistant to cefotaxime, and 35 (97.2%) were resistant to ampicillin, cefuroxime, cefepime, and ceftazidime. Additionally, the effective antibiotic against ESBL-producing GNB was imipenem.

Conclusion

Antibiotic utilization measures appear to contribute to the control of the emergence of multidrug-resistant pathogens such as ESBL and carbapenem-resistant GNB. Strict adherence to well-accepted infection control guidelines along with caution in using broad-spectrum antimicrobial agents represents the best strategy for preventing the emergence and spread of multidrug-resistant pathogens.

Genetic Diversity of Escherichia coli Coharboring mcr-1 and Extended Spectrum Beta-Lactamases from Poultry

Background. The emergence of resistance to beta-lactam agents in poultry results in multidrug-resistant (MDR) phenotypes in Escherichia coli isolates from poultry birds. The appearance of mobile colistin resistance (mcr) genes in the poultry sector has further worsened the situation. Therefore, the current study is aimed at investigating the molecular epidemiology of mcr harboring colistin-resistant E. coli among poultry. Methods. The isolation and identification of colistin-resistant E. coli (CR-Ec) were done from the broiler’s fecal samples through culturing using selective media supplemented with colistin sulfate (4 μg/ml). The antibiogram studies of the isolates were performed using the disc diffusion method and broth microdilution method as per CLSI guidelines. The screening for the genes conferring resistance to colistin as well as beta-lactam agents was performed by PCR. The genetic diversity of mcr-positive strains was assessed by multilocus sequencing typing (MLST). Results. Out of 500 fecal samples, 7% (35/500) were found positive for the presence of colistin-resistant E. coli (CR-Ec). Among the CR-Ec isolates, 74.28% (26/35) were detected as ESBL producers carrying the blaCTX-M-1 gene in 15/35 (42.85%) isolates and blaCTX-M-15 and blaTEM genes in 21/35 (60%) and 35/35 (100%) isolates, respectively. E. coli isolates were found positive for the presence of mcr-1, although none of the isolates exhibited the mcr-2 or mcr-3 genes. The MLST of CR-Ec has shown the ST1035 as the most prevalent genotype, while 82.85% (29/35) of CR-Ec strains belonged to clonal complex (CC) 131 comprising ST1035, ST131, ST1215, ST1650, and ST2279. Conclusions. The findings suggest a continuous monitoring system in veterinary and clinical settings to avoid unnecessary antibiotics. Further studies are needed at the national level to help control the increasing resistance among Enterobacterales in poultry settings.

Detection of NDM Variants (bla NDM-1, bla NDM-2, bla NDM-3) from Carbapenem-Resistant Escherichia coli and Klebsiella pneumoniae: First Report from Nepal

Background

Increasing burden of carbapenem resistance among Enterobacterales is attributable to their ability to produce carbapenemase enzymes like metallo-beta-lactamase (MBL), Klebsiella pneumoniae carbapenemase (KPC), and OXA-type. This study aimed to determine the prevalence of carbapenemases and MBL genes ((bla_NDM-1,bla_NDM-1 and bla_NDM-3) among E. coli and K. pneumoniae isolates.

Methods

A total of 2474 urine samples collected during the study period (July–December 2017) were processed at the microbiology laboratory of Kathmandu Model Hospital, Kathmandu. Isolates of E. coli and K. pneumoniae were processed for antimicrobial susceptibility testing (AST) by disc diffusion method. Carbapenem-resistant isolates were subjected to Modified Hodge Test (MHT) for phenotypic confirmation, and inhibitor-based combined disc tests for the differentiation of carbapenemase (MBL and KPC). MBL-producing isolates were screened for NDM genes by polymerase chain reaction (PCR).

Results

Of the total urine samples processed, 19.5% (483/2474) showed the bacterial growth. E. coli (72.6%; 351/483) was the predominant isolate followed by K. pneumoniae (12.6%; 61/483). In AST, 4.4% (18/412) isolates of E. coli (15/351) and K. pneumonia (3/61) showed resistance towards carbapenems, while 1.7% (7/412) of the isolates was confirmed as carbapenem-resistant in MHT. In this study, all (3/3) the isolates of K. pneumoniae were KPC-producers, whereas 66.7% (10/15), 20% (3/15) and 13.3% (2/15) of the E. coli isolates were MBL, KPC and MBL/KPC (both)-producers, respectively. In PCR assay, 80% (8/10), 90% (9/10) and 100% (10/10) of the isolates were positive for bla_NDM-1, bla_NDM-2 and bla_NDM-3, respectively.

Conclusion

Presence of NDM genes among carbapenemase-producing isolates is indicative of potential spread of drug-resistant variants. This study recommends the implementation of molecular diagnostic facilities in clinical settings for proper infection control, which can optimize the treatment therapies, and curb the emergence and spread of drug-resistant pathogens.

OXA-48-Like β-Lactamases: Global Epidemiology, Treatment Options, and Development Pipeline

Modern medicine is threatened by the rising tide of antimicrobial resistance, especially among Gram-negative bacteria, where resistance to β-lactams is most often mediated by β-lactamases. The penicillin and cephalosporin ascendancies were, in their turn, ended by the proliferation of TEM penicillinases and CTX-M extended-spectrum β-lactamases. These class A β-lactamases have long been considered the most important. For carbapenems, however, the threat is increasingly from the insidious rise of a class D carbapenemase, OXA-48, and its close relatives. Over the past 20 years, OXA-48 and "OXA-48-like" enzymes have proliferated to become the most prevalent enterobacterial carbapenemases across much of Europe, Northern Africa, and the Middle East. OXA-48-like enzymes are notoriously difficult to detect because they often cause only low-level in vitro resistance to carbapenems, meaning that the true burden is likely underestimated. Despite this, they are associated with carbapenem treatment failures. A highly conserved incompatibility complex IncL plasmid scaffold often carries bla_OXA-48 and may carry other antimicrobial resistance genes, leaving limited treatment options. High conjugation efficiency means that this plasmid is sometimes carried by multiple Enterobacterales in a single patient. Producers evade most β-lactam-β-lactamase inhibitor combinations, though promising agents have recently been licensed, notably ceftazidime-avibactam and cefiderocol. The molecular machinery enabling global spread, current treatment options, and the development pipeline of potential new therapies for Enterobacterales that produce OXA-48-like β-lactamases form the focus of this review.

Worldwide Prevalence of mcr-mediated Colistin-Resistance Escherichia coli in Isolates of Clinical Samples, Healthy Humans, and Livestock-A Systematic Review and Meta-Analysis

Background: Antimicrobial resistance is a serious public-health problem throughout the world. Escherichia coli, the most common Gram-negative microorganism, has developed different resistance mechanisms, making treating infections difficult. Colistin is considered a last-resort drug in the treatment of infections caused by E. coli. Plasmid-mediated mobile-colistin-resistant (mcr) genes in E. coli, now disseminated globally, are considered a major public-health threat. Humans, chickens, and pigs are the main reservoirs for E. coli and the sources of antibiotic resistance. Hence, an up-to-date and precise estimate of the global prevalence of mcr resistance genes in these reservoirs is necessary to understand more precisely the worldwide spread and to more effectively implement control and prevention strategies. Methodology: Publications were identified in the PubMed database on the basis of the PRISMA guidelines. English full-text articles were selected from December 2014 to March 2021. Descriptive statistics and a meta-analysis were performed in Excel and R software, respectively. Colistin resistance was defined as the molecular-genetic detection of the mcr genes. The crude and estimated prevalence were calculated for each host and continent. The studies were divided into two groups; community-based when they involved isolates from healthy humans, chickens, or pigs, and clinical studies when they involved only hospital, outpatient, or laboratory isolates. Results: A total of 1278 studies were identified and 218 were included in this systematic review and meta-analysis, divided into community studies (159 studies) and clinical studies (59 studies). The general prevalence of mcr-mediated colistin-resistant E. coli (mcrMCRE) was 6.51% (n = 11,583/177,720), reported in 54 countries and on five continents; Asia with 119 studies followed by Europe with 61 studies registered the most articles. Asia reported the major diversity of mcr-variants (eight of nine, except mcr-2). Worldwide, chickens and pigs proved to be the principal reservoir of mcr with an estimated prevalence of 15.8% and 14.9%, respectively. Healthy humans and clinical isolates showed a lower prevalence with 7.4% and 4.2% respectively. Conclusions: In this systematic review and meta-analysis, the worldwide prevalence of mcr in E. coli isolated from healthy humans, chickens, and pigs was investigated. A wide prevalence and distribution of mcr genes was demonstrated on all continents in E. coli isolates from the selected reservoirs. Understanding the epidemiology and occurrence in the reservoirs of mcr in E. coli on different continents of the world facilitates tracing how mcr genes are transmitted and determining the infection risks for humans. This knowledge can be used to reduce the incidence of zoonotic transmission by implementing the appropriate control programs.

Antibiotic Resistance, Biofilm Formation and Detection of mexA/mexB Efflux-Pump Genes Among Clinical Isolates of Pseudomonas aeruginosa in a Tertiary Care Hospital, Nepal

Efflux-pump system and biofilm formation are two important mechanisms Pseudomonas aeruginosa deploys to escape the effects of antibiotics. The current study was undertaken from September 2019 to March 2020 at a tertiary-care hospital in Kathmandu in order to ascertain the burden of P. aeruginosa in clinical specimens, examine their biofilm-forming ability and determine their antibiotic susceptibility pattern along with the possession of two efflux-pump genes-mexA and mexB. Altogether 2820 clinical specimens were collected aseptically from the patients attending the hospital and processed according to standard microbiological procedures. Identification of P. aeruginosa was done by Gram stain microscopy and an array of biochemical tests. All the P. aeruginosa isolates were subjected to in vitro antibiotic susceptibility testing and their biofilm-forming ability was also examined. Presence of mexA and mexB efflux-pump genes was analyzed by Polymerase Chain Reaction (PCR) using specific primers. Out of 603 culture positive isolates, 31 (5.14%) were found to be P. aeruginosa, of which 55% were multi-drug resistant (MDR). Out of 13 commonly used antibiotics tested by Kirby-Bauer disc diffusion method, greatest resistance was shown against piperacillin-tazobactam 15 (48.4%) and ceftazidime 15 (48.4%), and least against meropenem 6 (19.4%) and ofloxacin 5 (16.2%). Of all 17 MDR isolates subjected to biofilm detection, strong biofilm formation was exhibited by 11 (65%) and 14 (82%) isolates with microtiter plate method and tube method respectively. Out of 17 isolates tested, 12 (70.6%) isolates possessed mexA and mexB genes indicating the presence of active efflux-pump system. Higher number of the isolates recovered from sputum 7 (58.3%) and pus 5 (41.7%) possessed mexA/mexB genes while the genes were not detected at all in the isolates recovered from the urine (p&lt;0.05). This study assessed no significant association between biofilm production and multi-drug resistance (p&gt;0.05). Adoption of stern measures by the concerned authorities to curb the incidence of multi-drug resistant and biofilm-forming isolates is recommended to prevent their dissemination in the hospital settings.

Review on Multiple Facets of Drug Resistance: A Rising Challenge in the 21st Century

With the advancements of science, antibiotics have emerged as an amazing gift to the human and animal healthcare sectors for the treatment of bacterial infections and other diseases. However, the evolution of new bacterial strains, along with excessive use and reckless consumption of antibiotics have led to the unfolding of antibiotic resistances to an excessive level. Multidrug resistance is a potential threat worldwide, and is escalating at an extremely high rate. Information related to drug resistance, and its regulation and control are still very little. To interpret the onset of antibiotic resistances, investigation on molecular analysis of resistance genes, their distribution and mechanisms are urgently required. Fine-tuned research and resistance profile regarding ESKAPE pathogen is also necessary along with other multidrug resistant bacteria. In the present scenario, the interaction of bacterial infections with SARS-CoV-2 is also crucial. Tracking and in-silico analysis of various resistance mechanisms or gene/s are crucial for overcoming the problem, and thus, the maintenance of relevant databases and wise use of antibiotics should be promoted. Creating awareness of this critical situation among individuals at every level is important to strengthen the fight against this fast-growing calamity. The review aimed to provide detailed information on antibiotic resistance, its regulatory molecular mechanisms responsible for the resistance, and other relevant information. In this article, we tried to focus on the correlation between antimicrobial resistance and the COVID-19 pandemic. This study will help in developing new interventions, potential approaches, and strategies to handle the complexity of antibiotic resistance and prevent the incidences of life-threatening infections.

Global Prevalence and Molecular Epidemiology of mcr-Mediated Colistin Resistance in Escherichia coli Clinical Isolates: A Systematic Review

BACKGROUND AND AIM

The continuing rise in infections caused by multi-drug resistant (MDR) bacteria is one of the most serious public health issues in today's societies. Colistin is a last-resort antimicrobial medication used to treat infections caused by MDR gram-negative bacteria; therefore resistance to this antibiotic is extremely hazardous. The current study aimed to evaluate the global prevalence and distribution of colistin resistance genes among human clinical isolates of Escherichia coli (E. coli) as a systematic review.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. For further evaluation, all original English-language articles that demonstrated colistin resistance in E. coli clinical isolates published between 2000 and 2020 were examined.

RESULTS

Out of 4857 initial articles, after various stages of review and evaluation, 190 related articles were selected. More than 79 % of the publications selected in this research were published from 2014 to 2020. In Asia, Europe, America, Africa, and Oceania, the prevalence of mobilized colistin resistance (mcr) producing colistin-resistant E. coli was 66.72%, 25.48%, 5.19%, 2.27%, and 0.32 %, respectively.

CONCLUSION

The recent widespread spreading of E. coli strains harboring mcr conferring colistin resistance, especially in Asia and Europe, is concerning and needs more attention.

Antibiotic Resistance Profile of Common Bacteria Isolated from Blood Stream, Lower Respiratory Tract and Urinary Infections in Intensive Care Unit in Saudi Arabia: A Retrospective Study

Background

The rate of infections in the intensive care units (ICUs) is rising, mainly because of the increasing use of invasive procedures and specialized devices. This study aimed to identify the antibiotic resistance profile of common bacteria isolated from lower respiratory tract infections (LRTIs), bloodstream infections (BSIs), and urinary infections (UTIs) in ICUs in Saudi Arabia.

Methods

In the current retrospective study, the isolates and antibiotic resistance were collected from the Electronic Medical Record (EMR) for respiratory, blood, and urine samples. The study sample compromised 96 patients admitted to the ICU at least for 48 hours and have a central venous catheter (CVC) between November 1, 2020, and January 31, 2021.

Results

66 (68.8%) of the study sample were males, and 30 (31.2%) were females. LRTIs were the most common isolates (51 samples), followed by BSIs (28 samples) and UTIs (17 samples). The isolated pathogens in this study were Klebsiella pneumoniae (K. pneumoniae) (59.4%), Coagulase-negative staphylococci (CoNS) (11.5%), Escherichia coli (E. coli) (8.4%), Acinetobacter baumannii (A. baumannii) (7.3%), and Staphylococcus aureus (S. aureus) (6.2%). BSI were frequently caused by CoNS (35.7%) and K. pneumoniae (35.7%), while Methicillin-resistant Staphylococcus aureus (MRSA) represented 10.7% of BSI. Vancomycin, Synercid, and Teicoplanin were the commonly used antibiotics and showed 100% sensitivity among S. aureus, including MRSA, while almost 100% resistance was observed for penicillin and oxacillin against the same organisms. The maximum resistance was observed with aztreonam (96.4%), ampicillin (87.3%), followed by co-amoxiclav (83.9%), cotrimoxazole (79.5%) and cephalosporin group antibiotics.

Conclusions

Strict adherence to infection prevention practices and wise use of antibiotics are recommended to slow the spread of antimicrobial resistance (AMR).

Efficacy of Urine Dipstick Test in Diagnosing Urinary Tract Infection and Detection of the blaCTX-M Gene among ESBL-Producing Escherichia coli

A urine dipstick test used for prompt diagnosis of urinary tract infection (UTI) is a rapid and cost-effective method. The main objective of this study was to compare the efficacy of the urine dipstick test with culture methods in screening for UTIs along with the detection of the bla_CTX-M gene in extended spectrum β-lactamase (ESBL)-producing Escherichia coli. A total of 217 mid-stream urine samples were collected from UTI-suspected patients attending Bharatpur Hospital, Chitwan, and tested by dipstick test strip (COMBI-10SL, Germany) prior to the culture. E. coli isolates were identified by standard microbiological procedures and subjected to antimicrobial susceptibility testing by Kirby Bauer disc diffusion method following CLSI guideline. Primary screening of ESBL-producing E. coli isolates was conducted using ceftriaxone, cefotaxime and ceftazidime discs and phenotypically confirmed by combined disk diffusion test. Plasmid DNA of ESBL-producing strains was extracted by phenol-chloroform method and subjected to PCR for detection of the bla_CTX-M gene. Out of 217 urine samples, 48 (22.12%) showed significant bacteriuria. Among 46 (21.20%) Gram negative bacteria recovered, the predominant one was E. coli 37 (77.08%) of which 33 (89.19%) were multidrug resistant (MDR). E. coli isolates showed a higher degree of resistance towards cefazolin (62.16%) while 81.08% of the isolates were sensitive towards amikacin followed by nitrofurantoin (70.27%). Among 14 (37.84%) phenotypically confirmed ESBL isolates, only eight (21.62%) isolates carried the bla_CTX-M gene. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of urine dipstick test were 43.75%, 77.51%, 35.59% and 82.91%, respectively. Besides, the use of dipstick test strip for screening UTI was associated with many false positive and negative results as compared to the gold standard culture method. Hence, dipstick nitrite test alone should not be used as sole method for screening UTIs.

Antibiotic resistance and detection of plasmid mediated colistin resistance mcr-1 gene among Escherichia coli and Klebsiella pneumoniae isolated from clinical samples

BACKGROUND

The prevalence of antimicrobial resistance (AMR) among Gram-negative bacteria is alarmingly high. Reintroduction of colistin as last resort treatment in the infections caused by drug-resistant Gram-negative bacteria has led to the emergence and spread of colistin resistance. This study was designed to determine the prevalence of drug-resistance among beta-lactamase-producing strains of Escherichia coli and Klebsiella pneumoniae, isolated from the clinical specimens received at a tertiary care centre of Kathmandu, Nepal during the period of March to August, 2019.

METHODS

A total of 3216 different clinical samples were processed in the Microbiology laboratory of Kathmandu Model Hospital. Gram-negative isolates (E. coli and K. pneumoniae) were processed for antimicrobial susceptibility test (AST) by using modified Kirby-Bauer disc diffusion method. Drug-resistant isolates were further screened for extended-spectrum beta-lactamase (ESBL), metallo-beta-lactamase (MBL), carbapenemase and K. pneumoniae carbapenemase (KPC) production tests. All the suspected enzyme producers were processed for phenotypic confirmatory tests. Colistin resistance was determined by minimum inhibitory concentration (MIC) using agar dilution method. Colistin resistant strains were further screened for plasmid-mediated mcr-1 gene using conventional polymerase chain reaction (PCR).

RESULTS

Among the total samples processed, 16.4% (529/3216) samples had bacterial growth. A total of 583 bacterial isolates were recovered from 529 clinical samples. Among the total isolates, 78.0% (455/583) isolates were Gram-negative bacteria. The most predominant isolate among Gram-negatives was E. coli (66.4%; 302/455) and K. pneumoniae isolates were 9% (41/455). In AST, colistin, polymyxin B and tigecycline were the most effective antibiotics. The overall prevalence of multidrug-resistance (MDR) among both of the isolates was 58.0% (199/343). In the ESBL testing, 41.1% (n = 141) isolates were confirmed as ESBL-producers. The prevalence of ESBL-producing E. coli was 43% (130/302) whereas that of K. pneumoniae was 26.8% (11/41). Similarly, 12.5% (43/343) of the total isolates, 10.9% (33/302) of E. coli and 24.3% of (10/41) K. pneumoniae were resistant to carbapenem. Among 43 carbapenem resistant isolates, 30.2% (13/43) and 60.5% (26/43) were KPC and MBL-producers respectively. KPC-producers isolates of E. coli and K. pneumoniae were 33.3% (11/33) and 20% (2/10) respectively. Similarly, 63.6% (21/33) of the E. coli and 50% (5/10) of the K. pneumoniae were MBL-producers. In MIC assay, 2.2% (4/179) of E. coli and 10% (2/20) of K. pneumoniae isolates were confirmed as colistin resistant (MIC ≥ 4 µg/ml). Overall, the prevalence of colistin resistance was 3.1% (6/199) and acquisition of mcr-1 was 16.6% (3/18) among the E. coli isolates.

CONCLUSION

High prevalence of drug-resistance in our study is indicative of a deteriorating situation of AMR. Moreover, significant prevalence of resistant enzymes in our study reinforces their roles in the emergence of drug resistance. Resistance to last resort drug (colistin) and the isolation of mcr-1 indicate further urgency in infection management. Therefore, extensive surveillance, formulation and implementation of effective policies, augmentation of diagnostic facilities and incorporation of antibiotic stewardship programs can be some remedies to cope with this global crisis.

Use of antimicrobials and antimicrobial resistance in Nepal: a nationwide survey

Nepal suffers from high burden of antimicrobial resistance (AMR) due to inappropriate use of antibiotics. The main objective of this study was to explore knowledge, attitude and practices of antibiotics uses among patients, healthcare workers, laboratories, drug sellers and farmers in eight districts of Nepal. A cross-sectional survey was conducted between April and July 2017. A total of 516 individuals participated in a face-to-face interview that included clinicians, private drug dispensers, patients, laboratories, public health centers/hospitals and, livestock and poultry farmers. Out of 516 respondents, 62.8% (324/516) were patients, 16.9% (87/516) were clinicians, 6.4% (33/516) were private drug dispensers. A significant proportion of patients (42.9%; 139/324) thought that fever could be treated with antibiotics. Majority (79%; 256/324) of the patients purchased antibiotics over the counter. The knowledge of antibiotics used among patients increased proportionately with the level of education: literate only [AOR = 1.4 (95% Cl = 0.6-4.4)], versus secondary education (8-10 grade) [AOR = 1.8 (95% Cl = 1.0-3.4)]. Adult patients were more aware of antibiotic resistance. Use of antibiotics over the counter was found high in this study. Knowledge, attitude and practice related to antibiotic among respondents showed significant gaps and need an urgent effort to mitigate such practice.

Detection of TEM and CTX-M Genes in Escherichia coli Isolated from Clinical Specimens at Tertiary Care Heart Hospital, Kathmandu, Nepal

Background: Antimicrobial resistance (AMR) among Gram-negative pathogens, predominantly ESBL-producing clinical isolates, are increasing worldwide. The main aim of this study was to determine the prevalence of ESBL-producing clinical isolates, their antibiogram, and the frequency of ESBL genes (bla_TEM and bla_CTX-M) in the clinical samples from patients. Methods: A total of 1065 clinical specimens from patients suspected of heart infections were collected between February and August 2019. Bacterial isolates were identified on colony morphology and biochemical properties. Thus, obtained clinical isolates were screened for antimicrobial susceptibility testing (AST) using modified Kirby–Bauer disk diffusion method, while ESBL producers were identified by using a combination disk diffusion method. ESBL positive isolates were further assessed using conventional polymerase chain reaction (PCR) to detect the ESBL genes bla_TEM and bla_CTX-M. Results: Out of 1065 clinical specimens, 17.8% (190/1065) showed bacterial growth. Among 190 bacterial isolates, 57.4% (109/190) were Gram-negative bacteria. Among 109 Gram-negative bacteria, 40.3% (44/109) were E. coli, and 30.2% (33/109) were K. pneumoniae. In AST, 57.7% (n = 63) Gram-negative bacterial isolates were resistant to ampicillin and 47.7% (n = 52) were resistant to nalidixic acid. Over half of the isolates (51.3%; 56/109) were multidrug resistant (MDR). Of 44 E. coli, 27.3% (12/44) were ESBL producers. Among ESBL producer E. coli isolates, 58.4% (7/12) tested positive for the bla_CTX-M gene and 41.6% (5/12) tested positive for the bla_TEM gene. Conclusion: Half of the Gram-negative bacteria in our study were MDR. Routine identification of an infectious agent followed by AST is critical to optimize the treatment and prevent antimicrobial resistance.

Extended-Spectrum β-Lactamase and Carbapenemase Producing Gram-Negative Bacilli Infections Among Patients in Intensive Care Units of Felegehiwot Referral Hospital: A Prospective Cross-Sectional Study

Background

Owing to the specific risk profile of its residents, intensive care units (ICUs) are the best place for selection pressure and the epicenter for resistance development and dissemination. Infections with β-lactamase releasing Gram-negative bacilli (GNB) at ICUs are an emerging global threat. This study dogged the magnitude of extended-spectrum β-lactamase (ESBL) and carbapenemase releasing Gram-negative bacilli infections and associated factors among patients in the ICUs of Felegehiwot Referral Hospital, Ethiopia.

Methods

A cross-sectional study was done through February to June 2020. Wound swabs, urine, blood and sputum samples were collected from patients in the ICUs symptomatic for infections while excluding those under coma and shock. Bacterial species were verified using standard microbiological methods. Carbapenemase and ESBL production were identified using modified carbapenem inactivation and combined disk diffusion methods, respectively. Multivariable analysis was calculated for factors associated with ESBL production. P-value < 0.05 was taken as cut-off for statistical significance.

Results

Out of 270 patients in the ICU, 67 (24.8%) and 14 (5.2%) had infections with ESBL and carbapenemase releasing GNB, respectively. The most frequent ESBL producing isolates were P. aeruginosa (100%), E. cloacae (100%), K. pneumoniae (82.8%) and E. coli (64%). The predominant carbapenemase producer isolates were K. pneumoniae (27.6%) and E. cloacae (33.3%). Overall, 77 (81.1%) of species were multi-drug resistant. All GNB species were 100% resistant to tetracycline and ampicillin. They are also resistant to cefuroxime, ceftazidime, sulfamethoxazole-trimethoprim and cefotaxime. Prior hospitalization (AOR = 5.5, CI = 2.63-11.46), support with medical care devices (AOR = 23.7, CI = 4.6-12) and arterial intravenous catheterization (AOR = 2.7, CI = 1.3-5.3) had significant association with β-lactamase producing GNB infection.

Conclusion

Infection with ESBL and carbapenemase producing Gram-negative bacilli linked with an alarming degree of multi-drug resistant isolates is a major healthcare threat among patients in ICUs. Hence, strict adherence to infection prevention practices and wise use of antibiotics are recommended to slow the spread of antimicrobial resistance.

Detection of Plasmid-Mediated Colistin Resistant mcr-1 Gene in Escherichia coli Isolated from Infected Chicken Livers in Nepal

Background: Plasmid-mediated resistance to the colistin in poultry is considered as an emerging problem worldwide. While poultry constitutes the major industry in Nepal, there is a paucity of evidence on colistin resistance in Escherichia coli isolates causing natural infections in poultry. This study aimed to explore the prevalence of plasmid-mediated colistin resistance gene, mcr-1 in E. coli isolated from liver samples of dead poultry suspected of E. coli infections. Methods: A total of two hundred and seventy liver samples (227 broilers and 43 layers) from dead poultry suspected of colibacillosis were collected from post-mortem in the Central Veterinary Laboratory (CVL), Kathmandu, between 1 February and 31 July 2019. The specimens were processed to isolate and identify E. coli; an antimicrobial susceptibility test (AST) using disk diffusion method was performed with 12 different antibiotics: Amikacin (30 µg), ampicillin (10 µg), ciprofloxacin (5 µg), chloramphenicol (30 µg), cefoxitin (30 µg), ceftazidime (30 µg), ceftriaxone (30 µg), cotrimoxazole (25 µg), gentamicin (10 µg), imipenem (10 µg), levofloxacin (5 µg) and tetracycline (30 µg). Colistin resistance was determined by agar dilution method and colistin-resistant strains were further screened for plasmid-mediated mcr-1 gene, using conventional polymerase chain reaction (PCR). Results: Out of 270 liver samples, 53.3% (144/270) showed growth of E. coli. The highest number (54%; 109/202) of E. coli isolates was obtained in the liver samples from poultry birds (of both types) aged less than forty days. In AST, 95.1% (137/144) and 82.6% (119/144) of E. coli isolates were resistant against tetracycline and ciprofloxacin, respectively, while 13.2% (19/144) and 25.7% (37/144) isolates were resistant to cefoxitin and imipenem, respectively. In the same assay, 76.4% (110/144) E. coli isolates were multi-drug resistant (MDR). The phenotypic prevalence of colistin resistance was 28.5% (41/144). In the PCR assay, 43.9% (18/41) of colistin-resistant isolates were screened positive for plasmid-mediated mcr-1. Conclusion: The high prevalence of mcr-1 in colistin-resistant E. coli isolates in our study is a cause of concern for the probable coming emergence of colistin resistance in human pathogens, due to horizontal transfer of resistant genes from poultry to human isolates.