Distribution of disinfectant resistant genes in mcr-1-carrying Escherichia coli isolated from children in southern China. - Related Documents




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233601.0000Distribution of disinfectant resistant genes in mcr-1-carrying Escherichia coli isolated from children in southern China. BACKGROUND: Colistin, a polymyxin antibiotic, serves as a crucial defense against multidrug-resistant gram-negative bacteria, despite its nephrotoxicity. However, the plasmid-mediated mobilization of the polymyxin resistance gene, mcr-1, presents a significant public health threat. The widespread use of disinfectants has resulted in Escherichia coli (E. coli) carrying mcr-1 also showing disinfectant resistance. The aim of this study is to investigate the distribution of disinfectant genes and resistance to disinfectants in mcr-1-carring E coli from children in the South China. METHODS: We evaluated the distribution of twelve disinfectant-resistance genes by PCR. Evaluated the correlation between disinfectant-resistance genes and resistance to disinfectants and antibiotics. We also examined the correlation between the strains' biofilm formation and the presence of disinfectant-resistance genes. Bioinformatic tools were employed to analyze resistance genes, virulence genes, and insertion sequences. Five strains were randomly selected to examine the effects of sub-inhibitory concentration (sub-MIC) of 8 disinfectants on the expression of the mcr-1 gene by qRT-PCR. RESULTS: The most prevalent of the nine biocide resistance genes were mdfA, sugE(c), ydgE, and ydgF (n = 21; all 100 %). The qacG, qacF, sugE(p) and tehA gene was not detected. Furthermore, benzalkonium chloride (BC) and potassium hydrogen persulfate (PMPS)-based disinfectants were effective against all mcr-1-carrying E. coli strains. The majority of mcr-1 were distributed among the InHI2 plasmid types, although three strains lacked mcr-1 on their plasmids. Biofilm formation was observed in 48 % of the strains. emrD and sitABCD showed significant associations with the susceptibility of the strains to 84 disinfectants (P of 0.0351 and 0.0300). In addition, sitABCD was significantly associated with susceptibility to povidone-iodine (PVP-I) (P value of 0.0062). Compared to the untreated group, stimulation with sub-MIC of peracetic acid (PAA) and PVP-I resulted in decreased or increased mcr-1 expression in five E. coli strains, respectively (P of 0.0011 for PAA and P of 0.0476 for PVP-I). CONCLUSION: BC and PMPS based disinfectants were effective against all mcr-1 carrying E. coli strains. Most of the mcr-1 genes were distributed among the InHI2 plasmid types. The emrD and sitABCD genes are highly associated with resistance to 84 disinfectants, and the sitABCD gene was highly associated with resistance to PVP-I. PVP-I selective pressure may encourage the maintenance of mcr-1 gene in E. coli.202539551109
233110.9995Bacteriological and molecular study of fosfomycin resistance in uropathogenic Escherichia coli. The identification of genes associated with resistance has the potential to facilitate the development of novel diagnostic tests and treatment methods. The objective of this study was to examine the antibiotic resistance and Fosfomycin resistance genes in uropathogenic Escherichia coli (UPEC) in patients in Baghdad, Iraq. After analyzing 250 urine samples using various identification methods, including the examination of morphological characteristics, biochemical tests, and genetic detection, it was determined that E. coli was the most common bacteria present, accounting for 63.6% of the samples. Antibiotic susceptibility testing showed a significant prevalence of resistance to various antibiotics, with 99.3% of E. coli isolates exhibiting multiple drug resistance (MDR). Fosfomycin showed antibacterial properties against UPEC. The minimum inhibitory concentration (MIC) ranged from 512 to 1024 μg/mL, while the minimum bactericidal concentration (MBC) was 2048 μg/mL. In the time-kill assay, fosfomycin was effective against fosfomycin-resistant isolates within 8-12 h. The genetic determinants associated with fosfomycin resistance were examined through the utilization of polymerase chain reaction (PCR). The findings indicated that the genes murA, glpT, and cyaA were detected in all the isolates when genomic DNA was used as a template. However, all the tests yielded negative results when plasmid was used as a template. The genes fosA3 and fosA4 were detected in 8.6% and 5% of the isolates when genomic DNA was used as a template. When plasmid was used as a template, the genes fosA3 and fosA4 were found in 5.7% and 2.9% of the isolates, respectively. In conclusion, there is an increasing problem with antibiotic resistance in UPEC, with elevated rates of resistance to several antibiotics. The study also offers novel insights into the genetic foundation of fosfomycin resistance in UPEC.202438367167
230020.9994Determining the Disinfectants Resistance Genes and the Susceptibility to Common Disinfectants of Extensively Drug-Resistant Carbapenem-Resistant Klebsiella pneumoniae Strains at a Tertiary Hospital in China. Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has become a significant threat to global health. The application of chemical disinfectants is an effective infection control strategy to prevent the spread of CRKP in hospital environments. However, bacteria have shown reduced sensitivity to clinical disinfectants in recent years. Furthermore, bacteria can acquire antibiotic resistance due to the induction of disinfectants, posing a considerable challenge to hospital infection prevention and control. This study collected 68 CRKP strains from the Fifth Affiliated Hospital of Xinjiang Medical University in China from 2023 to 2024. These strains were isolated from the sputum, urine, and whole blood samples of patients diagnosed with CRKP infection. Antibiotic susceptibility tests were performed on CRKP strains. Concurrently, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of disinfectants (benzalkonium bromide, 1% iodophor disinfectant, alcohol, and chlorine-containing disinfectant) against the test isolates were determined by the broth microdilution method. The efflux pump genes (cepA, qacE, qacEΔ1, qacEΔ1-SUL1, oqxA, and oqxB) were detected using polymerase chain reaction. The results showed that 21 out of the 68 CRKP strains exhibited extensive drug resistance, whereas 47 were nonextensively drug-resistant. The MIC value for benzalkonium bromide disinfectants displayed statistically significant differences (p < 0.05) between extensively drug-resistant (XDR) and non-XDR strains. Additionally, the MBC values for benzalkonium bromide disinfectants and 1% iodophor disinfectants displayed statistically significant differences (p < 0.05) between XDR and non-XDR strains. The detection rates for the efflux pump genes were as follows: cepA 52.9%, qacE 39.7%, qacEΔ1 35.2%, qacEΔ1-SUL1 52.9%, oqxA 30.8%, and oqxB 32.3%. The detection rate of the qacEΔ1-SUL1 gene in XDR CRKP strains was significantly higher than in non-XDR CRKP strains (p < 0.05). This indicates a potential link between CRKP bacterial disinfectant efflux pump genes and CRKP bacterial resistance patterns. Ongoing monitoring of the declining sensitivity of XDR strains against disinfectants is essential for the effective control and prevention of superbug.202439166283
229930.9993Determining the resistance of carbapenem-resistant Klebsiella pneumoniae to common disinfectants and elucidating the underlying resistance mechanisms. INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection is a serious problem in hospitals worldwide, posing a particular risk to immunocompromised patients. Elimination strategies may prevent these drug-resistant bacteria from spreading within hospital environments. Here, the susceptibility of patient-derived CRKP strains to common chemical disinfectants and possible correlations between the presence of drug-resistance genes and increased resistance to disinfectants were investigated. METHODS: The minimum inhibitory (MIC) and the minimum bactericidal concentrations (MBC) of common chemical disinfectants against each CRKP strain were determined using agar dilution; K. pneumoniae ATCC700603 served as a standard. The presence of the drug-resistance genes qacΔE, qacA, acrA and qacE was determined using PCR. RESULTS: A total of 27 clinically isolated CRKP strains collected in our hospital from 2011 to 2013 exhibited sensitivity to the following common chemical disinfectants in decreasing order of sensitivity: 75% ethyl alcohol > 2% glutaraldehyde > "84" disinfectant > 0.2% benzalkonium bromide > 2% iodine tincture > 1% iodophor > 0.1% chlorhexidine acetate. Of the 27 strains, 59, 41, 19 and 15% contained qacΔE, qacA, acrA and qacE resistance genes; 15% carried acrA, qacΔE and qacA, and 26% carried both qacA and qacΔE. Comparative analysis indicated that drug-resistance genes were correlated with higher MIC values. CONCLUSION: These pan-resistant pathogenic CRKP strains contained various drug-resistance genes and exhibited relatively high resistance to ethyl alcohol, chlorhexidine acetate and iodophor. Monitoring the drug-resistance rates of CRKP strains displaying disinfectant resistance may facilitate appropriate and effective sterilisation and thus preventing the spread of these pan-resistant strains.201526184804
158240.9993Integrated Genomic and Phenotypic Characterization of an Mcr-10.1-Harboring Multidrug Resistant Escherichia coli Strain From Migratory Birds in China. Background: The global rise in antibiotic resistance among multidrug resistant (MDR) Gram-negative (GN) bacteria has posed significant health challenges, leading to the resurgence of colistin as a key defense against these bacteria. However, the widespread use of colistin has resulted in the rapid emergence of colistin resistance on a global scale. Ten members of the (mobile colistin resistance) mcr gene family, mcr-1 through mcr-10, have been reported and documented. Currently, bacteria reported to carry the mcr-10.1 gene are sensitive to colistin, but the mechanism underlying the low-level resistance phenomenon mediated by mcr-10.1 remains unclear. Methods: In this study, antimicrobial susceptibility testing (AST) was conducted on Escherichia coli (E.coli) isolated from Chinese migratory birds, resulting in the selection of 87 strains exhibiting MDR phenotypes. Whole-genome sequencing (draft) was performed on these 87 MDR E. coli strains, and for one of the E. coli strains carrying the mcr-10.1 gene, whole-genome sequencing, phenotypic characterization, AST and conjugation experiments were conducted to identify its resistance phenotypes and genetic characteristics. Results: Whole-genome sequencing (draft) of 87 MDR E. coli isolates revealed a diverse array of resistance genes, predominantly including aminoglycoside, β-lactam, tetracycline, and sulfonamide resistance genes. Remarkably, one isolate, despite being sensitive to colistin, harbored the mcr-10.1 gene. Further sequencing showed that mcr-10.1 was located in the conserved region of xerC-mcr-10.1, a hotspot for movable elements with various insertion sequences (ISs) or transposons nearby. Phenotypic characterization indicated that the MDR plasmid pGN25-mcr10.1 had no significant effect on the growth of GN25 and its derivatives but reduced the number of bacterial flagella. Conclusions: It is particularly important to note that bacteria harboring the mcr-10.1 gene may exhibit low minimum inhibitory concentration (MIC) values, but that the MIC values under colistin selective pressure can become progressively higher and exacerbate the difficulty of treating infections caused by mcr-10.1-associated bacteria. Therefore, vigilance for such "silent transmission" is warranted, and continuous monitoring of the spread of mcr-10.1 is necessary in the future.202540343190
233050.9993Antimicrobial and disinfectant resistance of Escherichia coli isolated from giant pandas. AIMS: The study aims to demonstrate the antimicrobial and disinfectant resistance phenotypes and genotypes of Escherichia coli isolates obtained from giant pandas (Ailuropoda melanoleuca). METHODS AND RESULTS: Antimicrobial testing was performed according to the standard disk diffusion method. The minimal inhibitory concentrations (MICs) of disinfectants were determined using the agar dilution method. All isolates were screened for the presence of antimicrobial and disinfectant resistance genes and further analysed for genetic relatedness by pulse-field gel electrophoresis (PFGE). Results showed that 46·6% of the isolates were resistant to at least one antimicrobial. Escherichia coli isolates showed resistance to fewer antimicrobials as panda age increased. Among antimicrobial-resistant E. coli isolates, the antimicrobial resistance genes blaCTX-M (88·2%) and sul1 (92·3%) were most prevalent. The disinfectant resistance genes emrE, ydgE/ydgF, mdfA and sugE(c) were commonly present (68·2-98·9%), whereas qac and sugE(p) were relatively less prevalent (0-21·3%). The frequencies of resistance genes tended to be higher in E. coli isolated in December than in July, and PFGE profiles were also more diverse in isolates in December. The qacEΔ1 and sugE(p) genes were higher in adolescent pandas than in any other age groups. PFGE revealed that antimicrobial resistance correlated well with sampling time and habitat. CONCLUSIONS: This study demonstrated that antimicrobial and disinfectant resistance was common in giant panda-derived E. coli, and the antimicrobial resistance was associated with sampling time and habitat. Escherichia coli could serve as a critical vector in spreading disinfectant and antimicrobial resistance. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that demonstrated the phenotypic and genetic characterizations of antimicrobial and disinfectant resistance in E. coli isolates from more than 60 giant pandas. Frequent transfer of pandas to other cages may lead to the dissemination of antimicrobial resistance. The study highlights the need for regularly monitoring the antimicrobial and disinfectant resistance in bacteria from giant pandas.201525846200
164260.9993Characterization of resistance genes and plasmids from sick children caused by Salmonella enterica resistance to azithromycin in Shenzhen, China. INTRODUCTION: Samonella is 1 of 4 key global causes of diarrhoeal diseases, sometimes it can be serious, especially for yong children. Due to the extensive resistance of salmonella serotypes to conventional first-line drugs, macrolides (such as azithromycin) have been designated as the most important antibiotics for the treatment of salmonella. Antimicrobial resistance is a major public health problem in the world, and the mechanism of azithromycin resistance is rarely studied. METHODS: This study determined the azithromycin resistance and plasmids of Salmonella enterica isolates from children attending the Shenzhen Children's Hospital. The susceptibility of ampicillin (AMP), ciprofloxacin (CIP), ceftriaxone (CRO), sulfamethoxazole (SMZ), chloramphenicol (CL), and azithromycin (AZM) were detected and the genes and plasmids from azithromycin-resistant Salmonella were detected by Illumina hi-seq and Nanopore MinIone whole genome sequencing (WGS) using a map-based method, and the genomic background of these factors was evaluated using various bioinformatics tools. RESULTS: In total, 15 strains of nontyphoid Salmonella strains that were isolated (including S. typhimurium, S.London, S. Goldcoast, and S.Stanley) demonstrated resistance to azithromycin (minimum inhibitory concentration,MIC from 32 to >256 µg/mL), and the resistance rate was 3.08% (15/487). The sensitivity test to other antibiotics demonstrated 100% resistance to AMP, and the resistance to SMZ and CL was 86.7% and 80.0%, respectively. Through WGS analysis, all isolates were positive for a plasmid-encoded mphA gene. Plasmid incompatibility typing identified five IncFIB(K), five IncHI2/HI2A/Q1, two IncC, one IncHI2/HI2A/N, one IncR, one IncFII and one IncHI2/HI2A plasmids. Sequence analyses of plasmids revealed extensive homology to various plasmids or transposons in regions involved in plasmid replication/maintenance functions and/or in antibiotic resistance gene clusters. CONCLUSION: mphA is the main gene involved in azithromycin, a macrolide, and resistance to Salmonella. It is usually located on plasmids and easily spreads, hence posing a great threat to the current treatment of Salmonella infection. The plasmid sequence similarities suggest that the plasmids acquired resistance genes from a variety of enterica bacteria and underscore the importance of a further understanding of horizontal gene transfer among enterica bacteria.202337065212
114070.9993High abundance of the colistin resistance gene mcr-1 in chicken gut-bacteria in Bangladesh. Colistin is considered a last-resort reserved drug for the treatment of critical human infections by Gram-negative bacteria. Phenotypic colistin-resistance is strongly associated with plasmid-mediated mobile colistin resistance (mcr) genes. The mcr-bearing Enterobacteriaceae have been detected in many countries from environments, animals, and humans. This study investigated phenotypic colistin-resistance and the distribution of mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes in chicken-gut bacteria in Bangladesh. Bacteria were isolated from poultry- and native-chicken droppings, and their susceptibilities to colistin were determined by agar dilution and E-test minimal inhibitory concentration (MIC) measurements. Multiplex polymerase chain reactions detected mcr-1 to mcr-5 genes. Overall, 61.7% (92/149) of the isolates showed colistin resistance by agar dilution assessment (MIC > 2.0 μg/mL). The phenotypic resistance was observed considerably higher in poultry-chicken isolates (64.6%, 64/99) than in native-chicken isolates (56%, 28/50; p = 0.373). All the resistant isolates showed MIC levels between > 2 and > 128 μg/mL. The mcr-genes (mcr-1and mcr-2 combined) were detected more in poultry gut bacteria (36.4%) than native-chicken isolates (20%, p = 0.06). Despite bacteria sources, mcr-genes appeared to be significantly associated with phenotypic colistin-resistance phenomena (p < 0.001). Prior colistin usage led to a substantial increase in the proportion of bacteria with mcr-genes and phenotypic resistance (p < 0.001).202033057111
204680.9993QRDR mutations, efflux system & antimicrobial resistance genes in enterotoxigenic Escherichia coli isolated from an outbreak of diarrhoea in Ahmedabad, India. BACKGROUND & OBJECTIVES: Diverse mechanisms have been identified in enteric bacteria for their adaptation and survival against multiple classes of antimicrobial agents. Resistance of bacteria to the most effective fluoroquinolones have increasingly been reported in many countries. We have identified that most of the enterotoxigenic Escherichia coli (ETEC) were resistant to several antimicrobials in a diarrhoea outbreak at Ahmedabad during 2000. The present study was done to identify several genes responsible for antimicrobial resistance and mobile genetic elements in the ETEC strains. METHODS: Seventeen ETEC strains isolated from diarrhoeal patients were included in this study. The antimicrobial resistance was confirmed by conventional disc diffusion method. PCR and DNA sequencing were performed for the identification of mutation in the quinolone resistance-determining regions (QRDRs). Efflux pump was tested by inhibiting the proton-motive force. DNA hybridization assay was made for the detection of integrase genes and the resistance gene cassettes were identified by direct sequencing of the PCR amplicons. RESULTS: Majority of the ETEC had GyrA mutations at codons 83 and 87 and in ParC at codon 80. Six strains had an additional mutation in ParC at codon 108 and two had at position 84. Plasmid-borne qnr gene alleles that encode quinolone resistance were not detected but the newly described aac(6')-Ib-cr gene encoding a fluoroquinolne-modifying enzyme was detected in 64.7 per cent of the ETEC. Class 1 (intI1) and class 2 (intI2) integrons were detected in six (35.3%) and three (17.6%) strains, respectively. Four strains (23.5%) had both the classes of integrons. Sequence analysis revealed presence of dfrA17, aadA1, aadA5 in class 1, and dfrA1, sat1, aadA1 in class 2 integrons. In addition, the other resistance genes such as tet gene alleles (94.1%), catAI (70.6%), strA (58.8%), bla TEM-1 (35.2%), and aphA1-Ia (29.4%) were detected in most of the strains. INTERPRETATION & CONCLUSIONS: Innate gene mutations and acquisition of multidrug resistance genes through mobile genetic elements might have contributed to the emergence of multidrug resistance (MDR) in ETEC. This study reinforces the necessity of utilizing molecular techniques in the epidemiological studies to understand the nature of resistance responsible for antimicrobial resistance in different species of pathogenic bacteria.201121911975
228390.9993Association of qacE and qacEDelta1 with multiple resistance to antibiotics and antiseptics in clinical isolates of Gram-negative bacteria. Clinical isolates of Enterobacter cloacae, Citrobacter freundii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia were tested for resistance to antibiotics and to the antiseptics benzalkonium chloride and cetyltrimethylammonium bromide. Furthermore, they were examined for the presence of the resistance genes qacE and qacEDelta1. qacEDelta1 was detected by PCR in 10% of all (n=103) and in 81% of multiply antibiotic-resistant strains (n=15). qacE was found in only one of 37 P. aeruginosa strains. The minimum inhibitory concentrations of benzalkonium chloride, cetyltrimethylammonium bromide, and ethidium bromide were not significantly different for qacEDelta1/qacE-positive or -negative strains. Our data indicate that multiply antibiotic-resistant Gram-negative bacteria are not necessarily more resistant to quaternary ammonium compounds than antibiotic-sensitive strains even though qacE or qacEDelta1 is present.200010650208
1182100.9993Disinfectant and heavy metal resistance profiles in extended spectrum β-lactamase (ESBL) producing Escherichia coli isolates from chicken meat samples. Biocidal compounds are frequently used as disinfectants in poultry industry and their widespread usage has risen concern due to the co-selection and persistence of antimicrobial resistance among bacteria. In this study, extended spectrum β-lactamase producing (ESBL) Escherichia coli isolates (n = 60) obtained from chicken meat were characterized by Pulsed Field Gel Electrophoresis (PFGE) and further tested for disinfectant and heavy metal resistance phenotypically and genotypically. Plasmid replicon types of these isolates were also determined. ESBL producing E. coli isolates were found to be resistant to ciprofloxacin (48.3 %) and gentamicin (15 %). The majority of these isolates (46.5 %) carried bla(CTX-M-55) gene. The isolates showed higher minimal inhibitory concentrations to cetylpyridinium chloride (90 %), cetyltrimethylammonium bromide (50 %), hexadecyltrimethylammonium bromide (46.7 %), triclosan (38.3 %), benzalkonium chloride (28.3 %), chlorhexidine (21.7 %), acriflavine (3.3 %), benzethonium chloride (1.7 %) and N-alkyl dimethyl benzyl ammonium chloride (1.7 %), but 18.3 % of the isolates were resistant to triclosan. Of the quaternary ammonium compounds (QACs) tolerance genes, mdfA, sugE(c), ydgE and ydgF were most present in all isolates, but the qacE, qacG, oqxA and oqxB genes were not detected. Of genes mediating the heavy metal resistance, the zitB gene was detected in all isolates, whereas the copA and cueO genes were detected in 96.67 % and 95 % of isolates, respectively. The IncFIB plasmid was commonly present (93.3 %) in ESBL producing E. coli isolates. Consequently, given the detection of genes mediating disinfectant and heavy metal resistance commonly in ESBL producing E. coli isolates as well as high rate of MICs against disinfectant compounds, the use of QACs for decontamination of the facilities may not be as effective as expected in poultry sector in Turkey.202235843029
5927110.9992The prevalence of, associations between and conjugal transfer of antibiotic resistance genes in Escherichia coli isolated from Norwegian meat and meat products. OBJECTIVES: To investigate the distribution of, associations between and the transferability of antimicrobial resistance genes in resistant Escherichia coli strains isolated from Norwegian meat and meat products. METHODS: The 241 strains investigated were collected within the frame of the Norwegian monitoring programme for antimicrobial resistance in bacteria from feed, food and animals (NORM-VET) during the years 2000-2003. PCR was carried out for detection of resistance genes. Conjugation experiments were carried out with the resistant isolates from meat as donor strains and E. coli DH5alpha as the recipient strain. Statistical analyses were performed with the SAS-PC-System version 9.1 for Windows. RESULTS: Resistance genes common in pathogenic E. coli were frequently found among the isolates investigated. Strains harbouring several genes encoding resistance to the same antimicrobial agent were significantly (P < 0.0001) more frequently multiresistant than others. Strong positive associations were found between the tet(A) determinant and the genetic elements sul1, dfrA1 and aadA1. Negative associations were found between resistance genes encoding resistance to the same antimicrobial agent: tet(A)/tet(B), sul1/sul2 and strA-strB/aadA1. The resistance genes were successfully transferred from 38% of the isolates. The transfer was more frequent from resistant isolates harbouring class 1 integrons (P < 0.001). CONCLUSIONS: Acquired resistance played a major role in conferring resistance among the isolates investigated. The possibility of transferring resistance increases both by increased multiresistance and by the presence of class 1 integrons. The conjugation experiments suggest that tet(A) and class 1 integrons are often located on the same conjugative plasmid.200616931539
1691120.9992The increasing threat of silver-resistance in clinical isolates from wounds and burns. PURPOSE: The widespread use of silver-containing compounds has led to emergence of silver-resistant bacteria. Few studies are available on the detectability of plasmid-mediated silver-resistance in developing countries. Therefore, we aimed to detect silver-resistance in isolates from wounds and burns, and to genetically characterize plasmid-mediated silver-resistance genes (sil genes). METHODS: One hundred and fifty clinical isolates were obtained from burns and wounds. They were identified using the suitable Analytical Profile Index and MicroScan identification systems. Their antimicrobial susceptibility was tested by the disk diffusion and broth microdilution methods. Their silver nitrate (AgNO(3)) minimum inhibitory concentration (MIC) was determined using the broth macrodilution method. The presence of different sil genes on plasmids extracted from silver-resistant isolates and the replicon types of the extracted plasmids were investigated using polymerase chain reaction (PCR). The ability of these plasmids to impart silver-resistance was tested by transformation. RESULTS: All except two isolates were multidrug-resistant. Nineteen silver-resistant bacterial isolates (12.6%) were detected; with AgNO(3) MIC ≥512 µg/mL. They were identified as Klebsiella pneumoniae (n=7), Staphylococcus aureus (n=4), Escherichia coli (n=2), Enterobacter cloacae (n=2), Pseudomonas aeruginosa (n=2) and Acinetobacter baumannii (n=2). PCR revealed the presence of different sil genes on the extracted plasmids. Plasmid transformation resulted in the transfer of silver-resistance to the resulting transformants. The extracted plasmids had different replicon types. CONCLUSION: Plasmid-mediated silver-resistance was detected for the first time, in clinical P. aeruginosa, A. baumannii and S. aureus isolates; in addition to its detection in K. pneumoniae, E. coli and Enterobacter cloacae. Therefore, strict monitoring on the use of silver compounds in medical settings is required; with implementation of an approved standardized method for silver-resistance detection.201931372006
5274130.9992Presence of heavy metal resistance genes in Escherichia coli and Salmonella isolates and analysis of resistance gene structure in E. coli E308. OBJECTIVES: With the wide use of heavy metals as feed additives in animal production, little attention has been paid to heavy metal resistance in pathogenic bacteria. This study was performed to investigate the presence of heavy metal resistance genes (HMRGs) in Escherichia coli and Salmonella isolates and its correlation with disinfectant resistance genes (DRGs) and antibiotic resistance genes (ARGs). METHODS: HMRGs of 178 E. coli and 294 Salmonella isolated from chicken broiler farms and retail meat were detected by PCR. Minimum inhibitory concentrations (MICs) of heavy metals were determined by the broth microdilution method. The complete genome of E. coli E308, which had indications of multidrug resistance, was recovered and assembled using third-generation sequencing. RESULTS: The frequency of different HMRGs in E. coli and Salmonella ranged from 0.60-77.0% and 0.30-87.1%, respectively. MICs of heavy metals for E. coli and Salmonella ranged widely from ≤12.5 mg/L to 1600 mg/L. Moreover, HMRGs (zntA, arsB, merA, pcoR, pcoA, pcoC and chrA) were found to be significantly associated with one or more DRGs [sugE(c), emrE, mdfA, ydgE/ydgF, qacF, sugE(p) and qacEΔ1] and ARGs (sul1, sul2, sul3, tetA, tetB, tetC, bla(TEM), bla(SHV) and bla(CTX)) (P < 0.05). CONCLUSION: This study demonstrated that HMRGs are widely present in E. coli and Salmonella isolated from chicken farms and retail meat. The association between HMRGs with DRGs and ARGs may lead to co-resistance to heavy metals and other antimicrobial agents.202032006752
1625140.9992Colistin-resistant Escherichia coli carrying mcr-1 in food, water, hand rinse, and healthy human gut in Bangladesh. BACKGROUND: One of the most significant public health concerns in today's world is the persistent upsurge of infections caused by multidrug resistant bacteria. As a result, clinicians are being forced to intervene with either less effective backup drugs or ones with substantial side-effects. Colistin is a last resort antimicrobial agent for the treatment of infections caused by multi-drug resistant gram-negative bacteria. METHODS: Escherichia coli (n = 65) isolated from street food (n = 20), hand rinse (n = 15), surface water (n = 10), and healthy human stool (n = 20) were tested for colistin resistance gene mcr-1 and response to antimicrobial agents. Antimicrobial resistance genes and virulence genes were detected by employing polymerase chain reaction. DNA fingerprinting of the strains were determined by pulsed-field gel electrophoresis. RESULTS: Screening of E. coli allowed us to confirm colistin resistance marker gene mcr-1 in 13 strains (street food, n = 4; hand rinse, n = 2; surface water, n = 4; and stool, n = 3); and two of these E. coli strains carrying mcr-1 harbored bla (TEM) gene encoding extended spectrum beta lactamase. Antibiotic assay results revealed all 13 E. coli strains carrying mcr-1 to be multi-drug resistant (MDR), including to colistin. The minimum inhibitory concentration (MIC) for colistin ranged from 2 to 6 μg/ml. DNA sequencing confirmed homogeneity of the nucleotide sequence for mcr-1, but the E. coli strains were heterogenous, as confirmed by pulsed-field gel electrophoresis suggesting horizontal transmission of colistin resistance in Bangladesh. CONCLUSION: Widespread dissemination of E. coli strains carrying mcr-1 encoding resistance to colistin in the present study is alarming as this is the last resort drug for the treatment of infections caused by MDR gram-negative bacteria resistant to almost all drugs used commonly.202032002025
2291150.9992Multiple mechanisms contributing to ciprofloxacin resistance among Gram negative bacteria causing infections to cancer patients. Fluoroquinolones have been used for prophylaxis against infections in cancer patients but their impact on the resistance mechanisms still require further investigation. To elucidate mechanisms underlying ciprofloxacin (CIP) resistance in Gram-negative pathogens causing infections to cancer patients, 169 isolates were investigated. Broth microdilution assays showed high-level CIP resistance in 89.3% of the isolates. Target site mutations were analyzed using PCR and DNA sequencing in 15 selected isolates. Of them, all had gyrA mutations (codons 83 and 87) with parC mutations (codons 80 and 84) in 93.3%. All isolates were screened for plasmid-mediated quinolone resistance (PMQR) genes and 56.8% of them were positive in this respect. Among PMQR genes, aac(6')-Ib-cr predominated (42.6%) while qnr genes were harbored by 32.5%. This comprised qnrS in 26.6% and qnrB in 6.5%. Clonality of the qnr-positive isolates using ERIC-PCR revealed that most of them were not clonal. CIP MIC reduction by CCCP, an efflux pump inhibitor, was studied and the results revealed that contribution of efflux activity was observed in 18.3% of the isolates. Furthermore, most fluoroquinolone resistance mechanisms were detected among Gram-negative isolates recovered from cancer patients. Target site mutations had the highest impact on CIP resistance as compared to PMQRs and efflux activity.201830115947
2306160.9992Resistance to nitrofurantoin is an indicator of extensive drug-resistant (XDR) Enterobacteriaceae. Introduction. Nitrofurantoin is one of the preferred antibiotics in the treatment of uropathogenic multidrug-resistant (MDR) infections. However, resistance to nitrofurantoin in extensively drug-resistant (XDR) bacteria has severely limited the treatment options.Gap statement. Information related to co-resistance or collateral sensitivity (CS) with reference to nitrofurantoin resistant bacteria is limited.Aim. To study the potential of nitrofurantoin resistance as an indicator of the XDR phenotype in Enterobacteriaceae.Methods. One hundred (45 nitrofurantoin-resistant, 21 intermediately resistant and 34 nitrofurantoin-susceptible) Enterobacteriaceae were analysed in this study. Antibiotic susceptibility testing (AST) against nitrofurantoin and 17 other antimicrobial agents across eight different classes was performed by using the Vitek 2.0 system. The isolates were screened for the prevalence of acquired antimicrobial resistance (AMR) and efflux pump genes by PCR.Results. In total, 51 % of nitrofurantoin-resistant and 28 % of intermediately nitrofurantoin resistant isolates exhibited XDR characteristics, while only 3 % of nitrofurantoin-sensitive isolates were XDR (P=0.0001). Significant co-resistance was observed between nitrofurantoin and other tested antibiotics (β-lactam, cephalosporin, carbapenem, aminoglycoside and tetracycline). Further, the prevalence of AMR and efflux pump genes was higher in the nitrofurantoin-resistant strains compared to the susceptible isolates. A strong association was observed between nitrofurantoin resistance and the presence of bla (PER-1), bla (NDM-1), bla (OXA-48), ant(2) and oqxA-oqxB genes. Tigecycline (84 %) and colistin (95 %) were the only antibiotics to which the majority of the isolates were susceptible.Conclusion. Nitrofurantoin resistance could be an indicator of the XDR phenotype among Enterobacteriaceae, harbouring multiple AMR and efflux pump genes. Tigecycline and colistin are the only antibiotics that could be used in the treatment of such XDR infections. A deeper understanding of the co-resistance mechanisms in XDR pathogens and prescription of AST-based appropriate combination therapy may help mitigate this problem.202133830906
5915170.9992Characterization of Two Macrolide Resistance-Related Genes in Multidrug-Resistant Pseudomonas aeruginosa Isolates. In analyzing the drug resistance phenotype and mechanism of resistance to macrolide antibiotics of clinical Pseudomonas aeruginosa isolates, the agar dilution method was used to determine the minimum inhibitory concentrations (MICs), and PCR (polymerase chain reaction) was applied to screen for macrolide antibiotics resistance genes. The macrolide antibiotics resistance genes were cloned, and their functions were identified. Of the 13 antibiotics tested, P. aeruginosa strains showed high resistance rates (ranging from 69.5-82.1%), and MIC levels (MIC90 > 256 μg/ml) to macrolide antibiotics. Of the 131 known macrolide resistance genes, only two genes, mphE and msrE, were identified in 262 clinical P. aeruginosa isolates. Four strains (1.53%, 4/262) carried both the msrE and mphE genes, and an additional three strains (1.15%, 3/262) harbored the mphE gene alone. The cloned msrE and mphE genes conferred higher resistance levels to three second-generation macrolides compared to two first-generation ones. Analysis of MsrE and MphE protein polymorphisms revealed that they are highly conserved, with only 1-3 amino acids differences between the proteins of the same type. It can be concluded that even though the strains showed high resistance levels to macrolides, known macrolide resistance genes are seldom present in clinical P. aeruginosa strains, demonstrating that a mechanism other than this warranted by the mphE and msrE genes may play a more critical role in the bacteria's resistance to macrolides.202033574864
1597180.9992Longitudinal Monitoring Reveals Persistence of Colistin-Resistant Escherichia coli on a Pig Farm Following Cessation of Colistin Use. Colistin-resistant bacteria harboring plasmid-mediated mcr genes are of concern as they may be a cause of serious nosocomial infections. It is hypothesized that cessation of colistin use as a feed additive for pigs will reduce the occurrence and distribution of mcr genes in farms. The aim of this study was to investigate this hypothesis by longitudinal monitoring and characterizing of mcr positive Escherichia coli (MCRPE) isolates after colistin was withdrawn on a central Thailand pig farm that previously had a high frequency of MCRPE. Colistin use ceased at the beginning of 2017, and subsequently 170 samples were collected from farrowing sows and suckling piglets (n = 70), wastewater (n = 50) and farm workers (n = 50) over a 3.5-year period. Bacteria were identified by MALDI-TOF mass spectrometry and minimal inhibitory concentrations were determined by broth microdilution. The antibiogram of mcr positive E. coli isolates was determined using the Vitek2 automated susceptibility machine, and multiplex and simplex PCRs were performed for mcr-1-8 genes. MCRPE containing either mcr-1 or mcr-3 were isolated from pigs throughout the investigation period, but with a declining trend, whereas MCRPE isolates were recovered from humans only in 2017. MCRPE were still being recovered from wastewater in 2020. Most MCRPE isolates possessed the virulence genes Stap, Stb, or Stx2e, reflecting pathogenic potential in pigs, and showed high rates of resistance to ampicillin, gentamicin and tetracycline. Pulsed-field gel electrophoresis and multi-locus sequence typing showed that diverse MCRPE clones were distributed on the farm. The study identified a decline of pathogenic MCRPE following withdrawal of colistin, with pigs being the primary source, followed by wastewater. However, short-term therapeutic usage of other antibiotics could enhance the re-occurrence of mcr-carrying bacteria. Factors including the environment, management, and gene adaptations that allow maintenance of colistin resistance require further investigation, and longer-term studies are needed.202235372535
1988190.9992Different fosA genes were found on mobile genetic elements in Escherichia coli from wastewaters of hospitals and municipals in Turkey. AIMS: The increasing number of globally established fosfomycin-resistant (Fos(R)) Gram-negative bacteria inspired us to investigate the occurrence of Fos(R)Enterobacterales populations (esp. E. coli) in samples of city wastewater treatment plants (WWTPs) and hospital sewage in Hatay, Turkey. Fos(R) target bacteria were further characterized for their clonal relatedness, resistomes and mobile genetic elements (MGEs) to evaluate their impact on fosfomycin resistance dissemination. METHODS: A total of 44 samples from raw and treated waters of WWTPs as well as of two hospitals in the Hatay province were subjected to selective cultivation for recovering Fos(R)Enterobacterales. The presence of fosA was verified by PCR and Sanger amplicon sequencing. Detected E. coli were further evaluated against antimicrobial susceptibility-testing, macrorestriction profiling (PFGE) and whole-genome sequencing (WGS). Bioinformatics analysis was performed for genome subtyping (i.e., MLST, serotype), resistome/virulome determination and dissection of the genetic determinants of plasmidic fosA3/4 resistances. RESULTS: Besides ten non-E. coli Enterobacterales, 29 E. coli were collected within this study. In silico-based subtyping revealed that E. coli isolates were assigned to six different serovars and 14 sequence types (ST), while O8:H21 and ST410 represented the major prevalent types, respectively. Fosfomycin resistance in the isolates was found to be mediated by the fosA4 (n = 18), fosA3 (n = 10) and fosA (n = 1), which are frequently associated with transmissible MGEs. Reconstruction of plasmid-associated fosA gene context revealed a linkage between the resistance cassette and IS6 (IS26 family) transposases, which might represent a major driver for the distribution of the genes and the generation of novel fosA-carrying plasmids. CONCLUSIONS: The occurrence of plasmid-mediated, transmissible Fos(R) in E. coli from wastewater pose a foreseeable threat to "One-Health". To minimize further spread of the resistances in bacterial populations associated with environmental, animal and human health further resistance monitoring and management strategies must be developed.202235182630