blaCTX-M Genes Research Articles

Bacterial diversity and detection of resistance genes to broad-spectrum betalactams in dairy family farm soils

Bovine mastitis is a complex disease that brings great losses to the dairy producer. The microbial diversity of the soils, as well as the presence of resistance genes in the environment directly influence the maintenance of mastitis in the farm. The objective of this work was to analyze the bacterial diversity in pasture soils of a dairy family farm, detecting enterobacteria that may be involved in the etiology of bovine mastitis, and to detect genes that encode broad-spectrum betalactamases in these soils. Twelve soil samples, representative of different areas of the farm located in the municipality of Barra do Piraí, Rio de Janeiro, were collected at different times of the year. Total DNA was extracted from the samples, gene amplified by Nested-PCR and then the amplification products were separated by DGGE (Denaturing Gradient Gel Electrophoresis). With the DGGE it was possible to construct dendograms that effectively represented the bacterial diversity of these soils. Eight of the soil samples were used to amplify the genes encoding the betalactamase enzymes TEM (blaTEM gene), SHV (blaSHV gene) and CTX (blaCTXM gene). In three of the eight soil samples, the blaSHV gene was found to be present. The blaTEM and blaCTX-M genes were not detected in any of the samples. The detection of genes encoding broad-spectrum betalactamases in dairy cattle pasture soils is of concern, because the transfer of gene material between pathogenic and non-pathogenic bacteria in this environment is a reality.

Emergence of ST1193 Clone in Maternal and Neonatal ESBL-Producing E. coli Isolates.

The emerging epidemic of extended-spectrum β-lactamase-producing E. coli (ESBL-EC) is a global public health crisis. ESBL-EC infections are increasing worldwide and contribute to morbidity and mortality among newborn infants. However, the antimicrobial resistance characteristics and clonal transmission of maternal and neonatal ESBL-EC isolates need to be further deciphered. We performed phenotypic and genotypic characterization of 33 ESBL-EC isolates from pregnant women and newborn during 2019-2020. Minimum inhibitory concentrations of 17 antimicrobial agents showed that all isolates were multidrug-resistant (MDR) and had a resistance rate of 100% to ampicillin, and mild resistance to florfenicol, gentamicin, ceftazidime, and amoxicillin-clavulanate. Additionally, imipenem, meropenem, polymyxin, and tigecycline exhibited good activity against the tested ESBL-EC isolates with low MIC50 (0.06-1 μg/mL) and MIC90 (0.06-1 μg/mL). Whole genome sequencing indicated that ESBL-EC isolates contained diverse antimicrobial resistant genes (blaCTX-M, blaTEM, blaSHV, tetA, etc.) and toxin genes (ompA, csg, fimH, hybtA, etc.). blaCTX-M genes were the main ESBL genotype. ST1193 (18.2%) was the second most abundant ST among the ESBL-EC isolates (ST131 was the most common, with 30.3%), and this is the first report of its mother-to-infant colonization transmission in China. These findings revealed the occurrence of high-risk ST1193 clone among ESBL-EC isolates from pregnant women and newborn colonization in China. Further national or regional multicenter studies are needed to assess the dissemination and evolution of ESBL-EC ST1193 clone as a nosocomial pathogen in China.

Kolistin direncinin moleküler tespitinde yanlış tanı: kolistine duyarlı Acinetobacter baumannii izolatlarında yanlış mcr-1-PCR pozitifliği

Purpose: The aim of this study was to investigate the presence of the mcr-1 gene, which is responsible for colistin resistance, in carbapenem-resistant Gram-negative bacteria that cause difficult-to-treat infections in a research hospital in Turkey. 
 Materials and Methods: The mcr-1 gene was examined using PCR in 103 carbapenem-resistant isolates, including 75 Acinetobacter baumannii, 19 Pseudomonas aeruginosa, and 9 Klebsiella pneumoniae. DNA sequencing was performed to confirm the mcr-1 positivity. Other antimicrobial resistance genes were investigated in isolates that were found to be mcr-1-positive by PCR and colistin-resistant isolates. 
 Results: Four (3.9% of the 103 carbapenem-resistant isolates and 5.3% of the 75 A. baumannii isolates) A. baumannii isolates, all susceptible to colistin, were found to be mcr-1-positive by PCR, whereas mcr-1 was not detected in four colistin-resistant isolates, one in A. baumannii and three in K. pneumoniae. DNA sequencing analysis determined that none of the amplification products was the targeted fragment, but they matched more than 70% with the chromosomal DNA fragments of A. baumannii strains. Therefore, these results were considered false-positive. Although these false-positive isolates were susceptible to colistin, they were extensively drug-resistant (XDR). Two of them were found to carry blaOXA23-like and blaTEM genes, another blaOXA23-like, blaTEM and blaOXA48-like genes, and the fourth one to have blaOXA23-like and blaCTXM genes. 
 Conclusion: Although the specificity of the primers used to detect the mcr-1 gene by PCR was reported as 100% in most studies, we concluded that PCR tests are insufficient yet to use alone or with antibiotic susceptibility tests in rapid routine diagnosis. Confirming at least PCR-positive samples using DNA sequence analysis would be appropriate for a certain period.

Molecular characterization of highly prevalent Escherichia coli and Escherichia marmotae resistant to extended-spectrum cephalosporins in European starlings (Sturnus vulgaris) in Tunisia.

European starlings are widespread migratory birds that have already been described as carrying bacteria resistant to extended-spectrum cephalosporins (ESC-R). These birds are well known in Tunisia because they spend the wintertime in this country and are hunted for human consumption. The goal of our study was to estimate the proportion of ESC-R in these birds and to characterize the collected isolates using whole-genome sequencing. Results showed that 21.5% (42/200) of the birds carried either an extended-spectrum beta-lactamase (ESBL) or an acquired AmpC gene. Diverse bla CTX-M genes were responsible for the ESBL phenotype, bla CTX-M-14 being the most prevalent, while only bla CMY-2 and one bla CMY-62 were found in AmpC-positive isolates. Likewise, different genetic determinants carried these resistance genes, including IncHI2, and IncF plasmids for bla CTX-M genes and IncI1 plasmids for bla CMY-2 genes. Three chromosomally encoded bla CTX-M-15 genes were also identified. Surprisingly, species identification revealed a large proportion (32.7%) of Escherichia marmotae isolates. This species is phenotypically indistinguishable from Escherichia coli and has obviously the same capacity to acquire ESC-R genes. Our data also strongly suggest that at least the IncHI2/pST3 plasmid can spread equally between E. coli and E. marmotae. Given the potential transmission routes between humans and animals, either by direct contact with dejections or through meat preparation, it is important to closely monitor antimicrobial resistance in European starlings in Tunisia and to set up further studies to identify the sources of contamination of these birds. IMPORTANCE The One Health concept highlighted knowledge gaps in the understanding of the transmission routes of resistant bacteria. A major interest was shown in wild migratory birds since they might spread resistant bacteria over long distances. Our study brings further evidence that wild birds, even though they are not directly submitted to antibiotic treatments, can be heavily contaminated by resistant bacteria. Our results identified numerous combinations of resistance genes, genetic supports, and bacterial clones that can spread vertically or horizontally and maintain a high level of resistance in the bird population. Some of these determinants are widespread in humans or animals (IncHI2/pST3 plasmids and pandemic clones), while some others are less frequent (atypical IncI1 plasmid and minor clones). Consequently, it is essential to be aware of the risks of transmission and to take all necessary measures to prevent the proportions of resistant isolates from increasing uncontrollably.

Genetic determinants of antibiotic resistance in enterobacteria isolated during microbiological monitoring in the perinatal center

Relevance. Currently, studies of the prevalence of antibiotic resistance and its genetic characteristics are focused primarily on the adult population, although infection with multiple drug infection has been registered as etiological agents of a general infection in obstetric and gynecological and pediatric institutions. The study of the prevalence of genetic determinants of antibiotic resistance is an important area of scientific research.Aim. To analyze the results of the studies carried out to identify the genetic determinants of antibiotic resistance of enterobacteria isolated during microbiological monitoring in the perinatal center.Materials and methods. The genetic profile of antibiotic resistance was studied in ESBL-producing strains isolated from 45 women and 35 children examined at the departments of the Federal State Budgetary Institution «NII OMM» of the Ministry of Health of Russia. To determine the determinants of antibiotic resistance, 80 non-duplicate strains of 7 species of the Enterobacteriaceae family were studied. DNA of bacterial cells was isolated from a daily culture of microorganisms using the PROBA-NK kit, detection of the tem, ctx-M-1, shv genes; oxa-40-like, oxa-48-like, oxa-23-like, oxa-51-like, imp, kpc, ges, ndm, vim were carried out using the diagnostic kit «BacResista GLA» on the detecting amplifier DT-48 (DNA -technology, Russia). To assess the statistical significance of differences in the frequency of occurrence of genes, Pearson's c2 test with Yates' correction was used.Results and discussion. When analyzing the results of studies on the molecular genetic detection of antibiotic resistance determinants, which we conducted in 2022, it was found that 8 genovariants were found in bacterial strains isolated from patients of the departments of the Research Institute of OMM in Yekaterinburg, providing resistance to beta-lactam antibiotics. The dominant genome, as in 2021, remains blaCTX-M-1, found in 29 cases. The blaTEM gene was identified both in association with other genes and as a single variant in Escherichiae coli and Klebsiella pneumoniae strains. Of the eight strains of K. pneumoniae, 4 were found to have three antibiotic resistance genes blaCTX-M, blaTEM, blaSHV, strains with a genetic profile of blaCTX-M, blaTEM, blaSHV, blaNDM were isolated once; and blaTEM, blaSHV, blaKPC. In one strain of K. pneumoniae, phenotypically showing resistance to AB, no genetic determinants of AB resistance were found. In addition to resistance to beta-lactam antibiotics, the strains demonstrate resistance to such groups of antibacterial drugs as fluoroquinolones, phosphonic acid derivatives (fosfomycin), and aminoglycosides. The data obtained indicate that the intestines of newborns during their stay at the stationary stage of nursing in some cases are colonized by strains of enterobacteria with multidrug resistance. Consequently, children are a reservoir of resistant microorganisms and can be sources of pathogens of infectious diseases in families and children's organized groups.

Multidrug-Resistant Escherichia coli from Raw Cow Milk in Namwala District, Zambia: Public Health Implications.

Escherichia coli (E. coli), a major foodborne disease-causing pathogen found in raw cow milk, has even far more reaching public health ramifications as it encodes for antimicrobial resistance (AMR). This study aimed to identify multidrug-resistant (MDR) E. coli from raw cow's milk and evaluate their antimicrobial-resistant profiles. In total, 418 pooled raw cow milk samples were collected from milk collection centers and analysed using standard culture methods to isolate E. coli. Antimicrobial Susceptibility Testing (AST) was conducted using the Kirby Bauer disk diffusion method and PCR was used to identify cefotaxime (CTX) resistant genes. Overall isolation of E. coli was 51.2% (214/418) with MDR observed in 21% (45/214) of isolates across different antibiotic combinations. Resistance was observed towards ampicillin (107/214, 50%), tetracycline (86/214, 40.1%), trimethoprim/sulfamethoxazole (61/214, 28.5%), and amoxicillin/clavulanic acid (CTX) (50/214, 23.4%). Notably, 15% (32/214) resistance to CTX was observed, while 12.6% (27/214) exhibited resistance to imipenem. The blaCTX-M and blaTEM genes were detected in CTX-resistant isolates. The findings of MDR E. coli that harbour blaCTX-M and blaTEM genes in raw cow's milk indicate serious public health risks for consumers.

The Aminoglycoside Resistance Genes, pehX, blaCTXM, blaAmpC, and npsB among Klebsiella oxytoca Stool Samples

Background: Klebsiella oxytoca may cause various infections, including respiratory, urinary, and bloodstream infections, often with multidrug-resistant strains posing challenges in treatment. The aim of this study was for molecular identification of K. oxytoca and to assess the existence of aminoglycoside resistance genes in biofilm and in toxin-producing and AmpC-positive isolates. Methods and Results: A total of 400 non-duplicate stool samples were collected from patients with colitis from 2019 to 2020 and were immediately cultured onto McConkey and blood agar (Merk, Germany). Antibiotic discs and Mueller-Hinton agar (MHA) culture medium (Merck, Germany) were used for antimicrobial susceptibility testing. The disk diffusion was done for susceptibility examination of them using CLSI 2020. Phenotypic detection of AmpC enzymes and biofilm formation were also determined. The PCR was performed to detect polygalacturonase (pehX) gene, blaCTX-M gene, npsB toxin-encoding gene, blaAmpC gene, and the aac(6′)-lb and aac(3′)-IIa AMEs genes. A total of 100 K. oxytoca were identified from stool samples. Most isolates were not susceptible to tetracycline, cotrimoxazole, or cefoxitin disks. Moreover, most were susceptible to amikacin and piperacillin-tazobactam disks. Among 100 isolates, 54% produced the AmpC enzyme in the combined disk method. Among them, 30 isolates were resistant to gentamicin. Strong biofilm formation was determined in 66% of isolates, and 30% of them produced moderate biofilms. Moreover, 4% of the isolates had weak biofilms. Among the 60 gentamicin-resistant K. oxytoca, 32 isolates had strong biofilms, and 11 isolates produced moderate ones. The pehX was used for the molecular identification of K. oxytoca; the results showed the presence of this gene in all isolates. The majority (98%) of K. oxytoca amplified the npsB toxin-encoding gene. The rate of blaCTX-M, blaAmpC, aac(6′)-lb, and aac(3)-IIa genes were 62%, 45%, 12%, 24%, respectively. Conclusion: In our study, more than half of K. oxytoca showed MDR phenotype. Moreover, half of the isolates carried the blaAmpC and blaCTX-M genes. Strong biofilm formation was observed in more than 60% of them.

Characterization of beta-lactamase producing Enterobacterales isolated from an urban community wastewater treatment plant in Iran.

he occurrence and characteristics of Extended Spectrum- and AmpC-β-lactamase producing Enterobacterales (ESBL-PE and AmpC-PE) in an urban wastewater treatment plant (WWTP) were investigated. A total of 30 wastewater samples were collected from all sections of WWTP. Enterobacterales were isolated and identified using standard microbiological tests. The antibiotic resistance profile was determined by the Kirby-Bauer disk diffusion method. Phenotypic screening for ESBL-PE and AmpC-PE isolates was performed by double-disk synergy and boronic acid disk potentiation tests, respectively. The isolates were examined for AmpC- and ESBL-encoding genes by PCR and sequencing methods. Among 146 Enterobacterales isolates, 8.9% (n=13) [ESBL-only; 5.48% (n=8) and ESBL + AmpC; 3.42% (n=5)] were ESBL-producers and 15.75% (n=23) [AmpC-only; 12.33% (n=18) and ESBL + AmpC; 3.42% (n=5)] AmpC-producers. Hafnia spp. with 33.33% (n=1/3) and E. coli with 20.58% (n=7/34) [ESBL-only; 17.64% (n=6/34) and ESBL + AmpC; 2.94% (n=1/34)] were the most common ESBL-producing bacteria. Enterobacter spp. with 37.50% (n=6/16) of isolates were the most common AmpC-producing organisms. ESBL- and/or AmpC-producing isolates were identified in all parts of the WWTP including 80% (n=8/10) of samples taken from effluent. Among ESBL-producing isolates, bla CTX-M , bla TEM, and bla SHV ESBL-encoding genes were found in 61.5% (n=8), 15.3% (n=2), and 7.7% (n=1) of isolates, respectively. All CTX-M-type enzymes belonged to the CTX-M-1 group and CTX-M-15 subgroup. bla TEM and bla SHV type genes belonged to bla TEM-20 and bla HSV-12 subtypes, respectively. bla DHA with 73.9% (n=17/23), and bla CIT and bla FOX with 30.4% (n=7/23) each, were the most common AmpC-encoding genes among AmpC-producing isolates. Overall, 75% of ESBL-producing and 55.5% of AmpC-producing isolates exhibited multi-drug resistance phenotypes. The organisms were most resistant against ampicillin (82.2%) nalidixic acid (43.8%) and cephalexin (41.1%). ESBL- and AmpC-producing Enterobacterales spp. with diverse genetic resistance backgrounds in WWTP effluent poses a significant risk to public health.

Molecular identification of blaTEM and blaCTX-M genes in multidrug-resistant Escherichia coli found in milk samples from dairy cattle farms in Tulungagung, Indonesia.

Escherichia coli is an opportunistic bacteria that can grow easily, produce toxins, and resist antibiotics. The phenomenon of E. coli developing multidrug resistance is currently the subject of extensive research. The objective of this study was to molecularly identify blaTEM and blaCTX-M genes in multidrug-resistant E. coli found in milk samples from dairy cattle farms in Tulungagung, Indonesia. One hundred and ten milk samples were collected from 45 dairy cattle farms in Tulungagung, Indonesia. Indole, methyl red, Voges-Proskauer and in citrate tests and triple iron sugar agar tests were used to identify E. coli. Multidrug resistance was determined in isolates through antibiotic sensitivity tests using tetracycline, streptomycin, trimethoprim, chloramphenicol and aztreonam. Extended-spectrum beta lactamase enzyme production was confirmed by double-disc synergy test (DDST). Molecular identification was performed to confirm the blaTEM and blaCTX-M genes. One hundred and one (91.82%) E. coli strains were isolated from the samples. The antibiotic sensitivity test showed four (3.96%) multidrug-resistant (MDR) and one (0.99%) ESBL-positive E. coli by DDST confirmation. There were three (77.78%) blaTEM genes and one (0.99%) blaCTX-M gene discovered in the MDR E. coli isolates using PCR for molecular identification. The findings of the blaTEM and blaCTX-M genes encoding ESBL E. coli in dairy cattle milk in Tulungagung, Indonesia is concerning and argues for prompt action to stop the emergence of antibiotic resistance which has an impact on public health.

Genomic Determinants and Antimicrobial Resistance Pattern of Clinical Isolates of Extended Spectrum Beta Lactamase (ESBL) Producing Escherichia coli

The growing prevalence of antibiotic-resistant bacteria is a worldwide public health apprehension, and Escherichia coli (E. coli) is one of the most commonly implicated bacterial species. Among E. coli isolates, extended-spectrum β-lactamase (ESBL)-producing strains have been identified as a key contributor to antibiotic resistance. Penicillin’s, cephalosporins, and monobactams are only a few of the β-lactam antibiotics that can be rendered inactive by ESBLs. This investigation’s goals were to determine the prevalence of ESBL-producing E. coli isolates found in clinical samples and to analyze the distribution of the blaTEM, blaSHV, and blaCTX-M genes among them. Additionally, we aimed to determine the antibiotic susceptibility patterns of these isolates to other antibiotics. Clinical isolates from urine, ear swab, and wound/pus swabs were collected from patients with suspected E. coli bacterial infections from different regions of north India viz., SKIMS-JVC medical college and NABL accredited Dr. Qadri’s Lab both from Srinagar Kashmir valley region and SMSR, SU from Greater Noida UP. Standard laboratory techniques were used to identify E. coli isolates, and the combined disc method and other phenotypic confirmation techniques were used to confirm ESBL formation. PCR amplification and sequencing were used to find the blaTEM, blaSHV, and blaCTX-M genes. The Kirby-Bauer disc diffusion method was used to test the antimicrobial susceptibility of various bacteria to different antibiotics. A total of 210 E. coli isolates were collected from different clinical samples and only 158 isolates showed positive results for ESBL by DDST and phenotypic confirmatory tests. Of these, 124 (78.48%) were ESBL-producing isolates. We found that blaTEM was the most prevalent gene (45.16%), followed by blaCTX-M (34.16%) and blaSHV (12.09%). Antimicrobial resistance profiles were assessed for each of the 120 isolates. Ampicillin and Cefepime were the most resistant drugs to ESBL-producing isolates, followed by Gentamicin, Ceftriaxone, and Cefixime.

First Emergence of NDM-5 and OqxAB Efflux Pumps Among Multidrug-Resistant Klebsiella pneumoniae Isolated from Pediatric Patients in Assiut, Egypt.

New Delhi metallo-β-lactamase (NDM)-producing K. pneumoniae poses a high risk, especially among Egyptian pediatric patients who consume carbapenems antibiotics very widely and without adequate diagnostic sources. In addition, presence of efflux pump genes such as OqxAB increases resistance against many groups of antimicrobials which exacerbates the problem faced for human health. This study aimed to determine NDM variants among K. pneumoniae strains isolated from pediatric patients in Egypt, analyze the presence of OqxAB genes, and molecular characterization ofblaNDM-5-positiveK. pneumoniae. Fifty-six K. pneumoniaeisolates were recovered from pediatric patients, and tested for carbapenemase by modified carbapenem inactivation methods (mCIM) test. Minimum inhibitory concentrations of meropenem and colistin were determined by meropenem E-test strips and broth microdilution, respectively. PCR was used for the detection of the resistant genes (ESBL gene (blaCTX-M), carbapenemase genes (blaNDM, blaKPC) colistin resistant (mcr1, mcr2)) and genes for efflux pump (oqxA and oqxB). BlaNDM was sequenced. The effect of efflux pump in NDM-5-producing isolates was assessed by measuring MIC of ciprofloxacin and meropenem before and after exposure to the carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The horizontal gene transfer ability ofblaNDM-5 was determined using liquid mating assay and PCR-based replicon typing (PBRT) was done to determine the major plasmid incompatibility group. Twenty-nine isolates were positive for blaNDM-1, nine isolates were positive for blaNDM-5, and 15 isolates were positive for blaKPC. There is a significant increase of meropenem MIC of NDM-5-positive isolates compared with NDM-1-positive isolates. In addition, 38 isolates were positive for CTX-M, and 15 isolates were positive for mcr1. Both OqxA and OqxB were detected in 26 isolates and 13 isolates were positive for OqxA while 11 isolates were positive for OqxB only. All NDM-5-producing isolates except one isolate could transfer their plasmids by conjugation to their corresponding transconjugants (E. coli J53). Plasmid replicon typing showed that FII was predominant in NDM-5-producing K. pneumoniae. Similar strains were found between the three isolates and similarity was also detected between the two isolates. The highly resistant K. pneumoniae producing blaNDM-5 type was firstly isolated from pediatric patients. The association of efflux pump genes such as OqxAB is involved in resistance to ciprofloxacin. This highlighted the severity risk ofblaNDM-5-positiveK. pneumonia as it could transfer blaNDM-5 to other bacteria and has more resistance against carbapenems. This underlines the importance of continuous monitoring of infection control guidelines, and the urgent need for a national antimicrobial stewardship plan in Egyptian hospitals.

Detection of blaCTX-M and blaDHA genes in stool samples of healthy people: comparison of culture- and shotgun metagenomic-based approaches.

We implemented culture- and shotgun metagenomic sequencing (SMS)-based methods to assess the gut colonization with extended-spectrum cephalosporin-resistant Enterobacterales (ESC-R-Ent) in 42 volunteers. Both methods were performed using native and pre-enriched (broth supplemented with cefuroxime) stools. Native culture screening on CHROMID® ESBL plates resulted in 17 positive samples, whereas the pre-enriched culture (gold-standard) identified 23 carriers. Overall, 26 ESC-R-Ent strains (24 Escherichia coli) were identified: 25 CTX-M and 3 DHA-1 producers (2 co-producing CTX-Ms). Using the SMS on native stool ("native SMS") with thresholds ≥60% for both identity and coverage, only 7 of the 23 pre-enriched culture-positive samples resulted positive for blaCTX-M/blaDHA genes (native SMS reads mapping to blaCTX-M/blaDHAs identified in gold-standard: sensitivity, 59.0%; specificity 100%). Moreover, an average of 31.5 and 24.6 antimicrobial resistance genes (ARGs) were detected in the 23 pre-enriched culture-positive and the 19 negative samples, respectively. When the pre-enriched SMS was implemented, more blaCTX-M/blaDHA genes were detected than in the native assay, including in stools that were pre-enriched culture-negative (pre-enriched SMS reads mapping to blaCTX-M/blaDHAs identified in gold-standard: sensitivity, 78.3%; specificity 75.0%). In addition, the pre-enriched SMS identified on average 38.6 ARGs/sample, whereas for the corresponding native SMS it was 29.4 ARGs/sample. Notably, stools resulting false-negative by using the native SMS had lower concentrations of ESC-R-Ent (average: ~105 vs. ~107 CFU/g) and E. coli classified reads (average: 193,959 vs. 1.45 million) than those of native SMS positive samples. Finally, the detection of blaCTX-M/blaDHA genes was compared with two well-established bioinformatic tools. In conclusion, only the pre-enriched SMS assured detection of most carriers of ESC-R-Ent. However, its performance was not comparable to the pre-enriched culture-based approach.

Characterization of young infants with fecal carriage of multidrug-resistant Escherichia coli in Southern Taiwan

The accelerating prevalence of extended-spectrum β-lactamase (ESBL)-producing and multidrug-resistance (MDR) Escherichia coli(E. coli) become a public health challenge worldwide. This study aimed to discuss the prevalence of drug-resistant E. coli colonization and analyze its risk factors and clinical characteristics among young infants in Southern Taiwan. Stool samples were collected from young infants, aged less than three months, within three days of their hospitalization from September to December 2019 in a tertiary hospital. A questionnaire was designed for parents to complete. E. coli colonies were selected and analyzed for antimicrobial susceptibility. PCR-based multilocus sequence typing was to detect the presence of sequence type ST131 and blaCTX-M genes. Among 100 enrolled infants, 36% had fecal carriage of E. coli isolates, of which twenty nine (80.5%) were MDR, thirteen (36.1%) were ESBL-producing isolates and five (13.8%) and ten (27.7%) were ST131 and strains carrying CTX-M-14 gene, respectively. Compared to non-ST131 and non-CTX-M-14 gene carrier, isolates of ST131 and CTX-M-14 gene carrier showed a significantly higher resistance rate to cefixime, ceftriaxone, and gentamycin, with p value all <0.05. The prevalence of ESBL-producing and MDR E. coli fecal carriage were both high in young infants. The most common sequence type is ST131, of which all are strains carrying CTX-M-14. Further surveillance and investigation to control for the high prevalence of antimicrobial-resistant E. coli fecal carriage among infants in Taiwan are warranted.

Prophage and Plasmid-Mediated Beta-Lactamases in Multidrug-Resistant Extraintestinal Escherichia coli

Abstract Objectives Antibiotic resistance can arise as a mutation to adapt to stress or be mediated by horizontal gene transfer. This study aimed at identifying the resistance determinants present in the mobile genetic elements of prophages and plasmids within multidrug-resistant (MDR) extraintestinal Escherichia coli. Materials and Methods Thirty-five anonymized MDR E. coli isolates of nonintestinal infections were confirmed for their antimicrobial resistance to six categories of antimicrobials by the disk diffusion test. Genes coding for beta-lactamases and carbapenemases in bacterial genome, plasmid, and prophage fractions were separately determined by polymerase chain reaction. Transducing ability of prophages carrying resistance genes was determined. Results Twenty-six isolates were positive for the gene bla CTX-M, nine for bla TEM, one each for bla KPC and bla VIM, thirteen for bla NDM, and seven for bla OXA. A majority of these isolates carried these determinants in plasmids and prophage fractions. Twenty-one percent of the prophage fractions (4 of 19) were able to successfully transfer resistance to sensitive isolates. Conclusions This study indicates bla CTX-M, bla TEM, and bla NDM genes that are reported most frequently in MDR isolates are more frequent in the plasmid and prophage fractions thus supporting for increased mobility.

Antimicrobial susceptibility and molecular characteristics of beta-lactam- and fluoroquinolone-resistant E. coli from human clinical samples in Nigeria

This study determined the antimicrobial resistance profiles and molecularly characterized beta-lactam- and fluoroquinolone-resistant E. coli recovered from human clinical samples. Three hundred (300) clinical samples collected from two major tertiary healthcare institutions were analyzed using standard microbiological techniques. Antimicrobial susceptibility testing and phenotypic detection of extended-spectrum beta-lactamase (ESBL) were done by disc diffusion and Double Disk Synergy Test. Molecular characterization for ESBL and fluoroquinolone-resistant genes were done by PCR with specific primers. In total, 44 (14.7%) ESBL-producing E. coli were recovered from human clinical specimens. The recovered isolates were multidrug-resistant with multiple antibiotics resistance index values ranging from 0.5–0.8. Isolates exhibited resistance to sulfamethoxazole/trimethoprim 44 (100%), cefoxitin 42 (95.5%), tetracycline 42 (95.5 %), cefuroxime 41 (93.2%), ciprofloxacin 40 (90.9%), cefotaxime 37 (84.1%), amoxicillin 37 (84.1%), amoxicillin/clavulanic acid 37 (84.1), and ceftazidime 35 (79.5%). BlaTEM 41 (93.2%) ESBL gene was the most predominant gene among the isolates, followed by blaCTX-M 9 (20.5%), and blaSHV 1 (2.3%) genes. Co-existence of blaTEM +blaSHV, blaTEM + blaCTX-M, and blaTEM +blaSHV + blaCTX-M genes was observed in 1 (2.3%), 7 (15.9%), and 4 (9.1%) isolates, respectively. All the fluoroquinolone-resistant isolates harbored aac-lb-6-cr gene while Qnr gene was absent. Association of fluoroquinolone resistance- and β-lactam resistance genes; aac-lb-6-cr + blaTEM + blaSHV + blaCTM was observed in 5 (11.4%) isolates. Our study showed high frequency of ESBL-producing E. coli harboring ESBL and fluoroquinolone resistance genes from human clinical samples in Ebonyi State, Nigeria. The high frequency of multidrug-resistant E. coli in our study is very worrisome and could have significant public health impact such as treatment failures, and possibly death, if not properly managed. It is therefore imperative to establish strong regulative measures and guidelines that would help in curtailing the increasing dissemination of these superbugs in healthcare institutions in Nigeria.

Primary Carrier Status and Alteration in the Colonization of the Extended-Spectrum β-Lactamase Producing Enterobacteriaceae Among Children in Pediatric Intensive Care Unit During the Hospital Stay

Background: Widespread and inappropriate use of antibiotics has led to an increase in antibiotic-resistant bacteria worldwide. Extended-spectrum β-lactamases (ESBLs) are among the most important resistance mechanisms in members of Enterobacteriaceae, which can pose a threat to patients. Objectives: This study aimed to investigate the carrier status and alteration in the fecal transmission of ESBL-producing Enterobacteriaceae (ESBL-E) on admission and during the hospital stay, as well as its correlation with the usage of antibiotics among children in a pediatric intensive care unit (PICU). Molecular typing between the primary and secondary isolates was done to detect the homotypic clonal strains. Methods: Demographic and medical data of PICU children were collected, and the carrier status of ESBL-E was investigated in pairs of their rectal swab samples at the admission and discharge time. Detection of ESBL phenotype and antimicrobial susceptibility to 12 antibiotics were performed by double-disk synergy and disc diffusion methods, respectively. Polymerase chain reaction for detection of blaTEM, blaSHVblaPER, blaCTX-M, and blaVEB genes was performed using specific primers. The phylogenetic relations were analyzed by the enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) method. Results: Extended-spectrum β-lactamase-producing Enterobacteriaceae was detected in 48% of the samples at admission and 42% at discharge time. The highest frequency of resistance was observed in cephazolin, amoxicillin-clavulanic acid, and ampicillin. Children with a history of meropenem administration showed a significantly higher frequency of meropenem resistance Enterobacteriaceae in their samples. Moreover, the administration of metronidazole increased the isolation of ESBL-Escherichia species in hospitalized children. The most common gene associated with the ESBL phenotype was blaCTX-M, while blaPER and blaVEB were not detected in the ESBL-E isolates. The phylogenetic analysis did not confirm the occurrence of the cross-transmission of ESBL-E in the patients during hospitalization. Conclusions: Our results showed a high frequency of ESBL-E in the feces of children upon admission to the PICU, which did not change significantly during the hospital stay. Although the prescription of metronidazole showed an association with the enrichment of ESBL-E due to observed diversity in the molecular types and resistance phenotypes of the isolates, the community seems to be the primary source of ESBL-E transmission in children. Further investigations are needed to understand the role of hospital stay in the colonization and enrichment of ESBL-E in the intestinal tract of children and their association with infections during the medical interventions in the PICU.

Drug resistance and molecular typing of diarrheagenic escherichia coli from the diarrhea clinics in Qingpu District, Shanghai City from 2015 to 2019

Objective: To analyze the drug resistance and multilocus sequence typing of five types of diarrheagenic Escherichia coli (DEC) isolated from diarrhea outpatients of diarrhea comprehensive monitoring designated hospital in Qingpu District, Shanghai City from 2015 to 2019. Methods: From January 2015 to December 2019, five types of DEC, isolated and identified from diarrhea outpatient cases' anal swabs of the Qingpu branch of Zhongshan Hospital were collected to determine the minimal inhibitory concentration by using the micro broth dilution susceptibility test. The strains, resistant to the third-generation cephalosporins or carbapenems, or producing ESBLs, were selected based on the results of sensitivity tests and determined by WGS. The MLST typing of DEC was analyzed based on the WGS technology and the minimum spanning tree was constructed by BioNumerics 7.6 software to analyze the local dominant flora. Results: A total of 513 strains of DEC were detected and isolated from 4 494 anal swabs, with a detection rate of 11.42%. About 500 strains were tested for drug sensitivity to nine antibiotics in four classes, including 330 strains of enterotoxigenic E.coli (ETEC), 72 strains of enteroaggregative E.coli (EAEC), 95 strains of enteropathogenic E.coli (EPEC), 1 strain of enterohemorrhagic E.coli (EHEC), and 2 strains of enteroinvasive E.coli (EIEC). From 2015 to 2019, the resistance rate of cefotaxime-clavulanic acid was significantly different (P<0.05). The resistance rate of virulence types of DEC to nalixic acid was significantly different (P<0.05). About 71 strains of DEC were determined by WGS, and 77 drug-resistant genes were detected. Strains were classified into 32 ST subtypes, with the dominant genotypes being ST-1491 (29.6%, 21/71) and ST-10 Complex (23.9%, 17/71). All ST-1491 produced ESBLs, which were blaCTX-M gene mutant strains. The dominant type of ST-10 complex was ST-218 (35.3%, 6/17). In addition, 8 strains of EAEC, 14 strains of EPEC and 49 strains of ETEC were classified into 7, 14 and 18 ST subtypes, respectively. Conclusion: The drug resistance of DEC strains from the diarrhea outpatient case of Qingpu District is serious. The ST types of EAEC and EPEC are highly polymorphic. The dominant ST types of DEC are basically consistent with the common genotypes in southeast China.

High frequency and molecular characterization of ESBL-producing Enterobacteriaceae isolated from wound infections in North Lebanon

ABSTRACT Background Extended-spectrum beta-lactamases producing Enterobacteriaceae (ESBL-PE) represent a major problem in wound infections. Here, we investigated the prevalence and molecular characterization of ESBL-PE associated with wound infections in North Lebanon. Research design and methods A total of 103 non-duplicated E. coli and K. pneumoniae strains isolated from 103 patients with wound infections, were collected from seven hospitals in North Lebanon. ESBL-producing isolates were detected using a double-disk synergy test. In addition, multiplex polymerase chain reaction (PCR) was used for the molecular detection of ESBLs genes. Results E. coli was the predominant bacteria (77.6%), followed by K. pneumoniae (22.3%). The overall prevalence of ESBL-PE was 49%, with a significantly higher rate among females and elderly patients. K. pneumoniae was the common MDR and ESBL-producer bacteria (86.95% and 52.17%) compared to E. coli (77.5% and 47.5%). Most of the isolated ESBL producers harbored multiple resistant genes (88%), where blaCTX-M was the most predominant gene (92%), followed by blaTEM (86%), blaSHV (64%), and blaOXA genes (28%). Conclusions This is the first data on the ESBL-PE prevalence associated with wound infections in Lebanon, showing the emergence of multidrug-resistant ESBL-PE, the dominance of multiple gene producers, and the widespread dissemination of blaCTX-M and blaTEM genes.

P14 Optimization of real-time sequencing for rapid detection of bacterial species and antimicrobial resistance in blood and urine infections

Abstract Objectives To optimize the process to obtain bacterial DNA directly from human urine and blood samples to produce high-quality genomic data using long-read Nanopore sequencer. Methods A total of 22 blood cultures and 24 urine samples positive for Escherichia coli or Klebsiella pneumoniae and corresponding isolates were collected from the microbiology diagnostics laboratory. DNA isolation optimization was performed testing three different sample volumes and seven DNA extraction kits. DNA concentration was quantified with Qubit fluorometer. Nanopore sequencing was performed on a MinION Mk1C device in R9.4.1 flow cells using the Rapid Barcoding Kit. Bacterial species and antimicrobial resistance (AMR) genes were determined with EPI2ME ARMA pipeline. Genomes were assembled with Flye, polished with Medaka and remaining human contigs removed with Krakentools. Bacterial isolates from the same samples were also sequenced using Illumina technology. Illumina and Nanopore assemblies were quality checked with Quast, Kraken was used to identify bacterial species, MLST for multilocus sequence typing and ABRicate with ResFinder database to detect AMR genes. Results A total of 72 DNA extractions from 24 urine and 22 blood samples with different kits were performed to find the optimal extraction protocol for each sample type. DNA from urine samples was isolated from 5 mL, while 1 mL was best for blood cultures. We found that the host depletion step prior to DNA extraction using MolYsis basic 5 Kit (VH-Bio) was essential. DNA from urine samples was extracted with GenElute Bacterial Genomic DNA Kit (Merck) and QIAamp Biostic bacteremia Kit (Qiagen) was best to allow successful bacterial genome sequencing for blood samples. Bacterial isolates from 11 urine and 1 blood sample (out of 54 sequenced) were successfully sequenced. In all 12 cases, the highest percentage of bacterial reads matched with the causative organism found during routine microbiology diagnostics (E. coli). A variety of clinically relevant AMR genes were detected, such as dfrA and bla CTX-M genes, which matched the phenotypic antimicrobial susceptibility testing results. Comparison of genomic assemblies obtained through Nanopore sequencing of 10 urine samples and Illumina sequencing of the corresponding clinical isolates showed a high degree of matching, validating Nanopore sequencing as an alternative option to support diagnosis and treatment choice. Conclusions We have successfully optimized the protocols to extract and sequence pathogenic bacterial DNA directly from blood and urine samples. Short-read sequencing confirmed results acquired by Nanopore sequencer, endorsing long-read sequencing in clinical settings to support timely diagnosis and treatment.

Characterization of Multiple Resistance Genes of Escherichia coli Strains Isolated from Food and Clinical Samples.

Multi-drug resistance (MDR), which is formed by the development of antimicrobial resistance, which is one of the defense mechanisms in bacteria, has pushed human beings to constantly seek new antimicrobial agents in the fight against these microorganisms. Speed and precision are very important in identifying resistance in strains with MDR that reach humans in an open system through the consumption of contaminated food or water. The main aim of this study was the molecular characterization of ESBL gene variants (blaTEM, blaOXA, blaSHV, and blaCTX-M), integron genes (int1, int2, and int3), and sulphonamide (sul1, sul2, and sul3) resistance genes by PCR from E. coli isolates originated from food and clinical samples. A total of 17 sets of primers were used for phylogenetic identification, molecular detection, and resistance and integron gene characterization of phenotypically identified E. coli isolates. The 45 red meat samples were collected from local markets, which are located in four (Adıyaman, Gaziantep, Kahramanmaraş, and Hatay) different provinces, clinical isolates were obtained from urine samples of patients with UTI from Şanlıurfa Mehmet Akif İnan Training and Research Hospital. Three gene groups were screened with 3 multiplex PCR applications in 63 food and 33 clinical isolates found to be E. coli by molecular identification. In terms of the 3 gene groups screened in food samples, the highest rates were found in the blaSHV gene at 44.44%, the sul1 gene at 69.84% and the int2 gene at 73.02%; in clinical samples, it is listed as blaCTX-M gene at 15.15%, sul2 gene at 81.82% and int1 gene at 54.55%. In terms of 3 gene groups scanned, the presence of 3 or more genes, including at least one gene from each gene group, was detected in 31 isolates from food samples and 2 isolates from clinical samples. Overall, it can be said that the high frequency of MDR genes isolated from E. coli-contaminated red meat samples and clinical samples gives a clue about the overuse of antibiotics in Türkiye.