Novel E. coli ST5123 Containing blaNDM-1 Carried by IncF Plasmid Isolated from a Pediatric Patient in Serbia

Carbapenem resistance determinants and their transmissibility among clinically isolated Enterobacterales in Lebanon

BACKGROUND

The occurrence of carbapenem-resistant bacterial infections has increased significantly over the years with Gram-negative bacteria exhibiting the broadest resistance range. In this study we aimed to investigate the genomic characteristics of clinical carbapenem-resistant Enterobacterales (CRE).

METHODS

Seventeen representative multi-drug resistant (MDR) isolates from a hospital setting showing high level of resistance to carbapenems (ertapenem, meropenem and imipenem) were chosen for further characterization through whole-genome sequencing. Resistance mechanisms and transferability of plasmids carrying carbapenemase-encoding genes were also determined in silico and through conjugative mating assays.

RESULTS

We detected 18 different β-lactamases, including four carbapenemases (blaNDM-1, blaNDM-5, blaNDM-7, blaOXA-48) on plasmids with different Inc groups. The combined results from PBRT and in silico replicon typing revealed 20 different replicons linked to plasmids ranging in size between 80 and 200 kb. The most prevalent Inc groups were IncFIB(K) and IncM. OXA-48, detected on 76-kb IncM1 conjugable plasmid, was the most common carbapenemase. We also detected other conjugative plasmids with different carbapenemases confirming the role of horizontal gene transfer in the dissemination of antimicrobial resistance genes.

CONCLUSION

Our findings verified the continuing spread of carbapenemases in Enterobacterales and revealed the types of mobile elements circulating in a hospital setting and contributing to the spread of resistance determinants. The occurrence and transmission of plasmids carrying carbapenemase-encoding genes call for strengthening active surveillance and prevention efforts to control antimicrobial resistance dissemination in healthcare settings.

Co-Harboring of Beta-Lactamases and mcr-1 Genes in Escherichia coli and Klebsiella pneumoniae from Healthy Carriers and Backyard Animals in Rural Communities in Ecuador

Few studies have addressed drug resistance of Enterobacterales in rural communities in developing countries. This study aimed to determine the coexistence of extended-spectrum β-lactamase (ESBL) and carbapenemase genes in Escherichia coli and Klebsiella pneumoniae strains carrying the mcr-1 gene in rural communities in Ecuador from healthy humans and their backyard animals. Sixty-two strains, thirty E. coli and thirty-two K. pneumoniae strains carrying the mcr-1 gene were selected from a previous study. PCR were performed for the presence of ESBLs and carbapenemase genes. The strains were further characterized, and the genetic relationship was studied with multi-locus sequencing typing (MLST) of seven housekeeping genes. Fifty-nine of the sixty-two mcr-1 isolates (95%) harbored at least on β-lactam resistance gene. The most prevalent ESBL genes were the bla_TEM genes (present in in 80% of the E. coli strains) and the bla_SHV gene (present in 84% of the K. pneumoniae strains). MSLT analysis revealed 28 different sequence types (ST); 15 for E. coli and 12 for K. pneumoniae, with most ST never described in humans and animals. The coexistence of mcr-1 and β-lactams resistant genes in E. coli and K. pneumoniae strains is alarming and threatens the efficacy of last-resort antibiotics. Our findings highlight backyard animals as a reservoir of mcr-1/β-lactams resistant genes.

Polyphenols as Inhibitors of Antibiotic Resistant Bacteria-Mechanisms Underlying Rutin Interference with Bacterial Virulence

The rising incidence of antibiotic resistant microorganisms urges novel antimicrobials development with polyphenols as appealing potential therapeutics. We aimed to reveal the most promising polyphenols among hesperetin, hesperidin, naringenin, naringin, taxifolin, rutin, isoquercitrin, morin, chlorogenic acid, ferulic acid, p-coumaric acid, and gallic acid based on antimicrobial capacity, antibiofilm potential, and lack of cytotoxicity towards HaCaT, and to further test its antivirulence mechanisms. Although the majority of studied polyphenols were able to inhibit bacterial growth and biofilm formation, the most promising activities were observed for rutin. Further investigation proved rutin’s ability to prevent/eradicate Pseudomonas aeruginosa and MRSA urinary catheter biofilms. Besides reduction of biofilm biomass, rutin antibiofilm mechanisms included reduction of cell viability, exopolysaccharide, and extracellular DNA levels. Moderate reduction of bacterial adhesion to human keratinocytes upon treatment was observed. Rutin antivirulence mechanisms included an impact on P. aeruginosa protease, pyocyanin, rhamnolipid, and elastase production and the downregulation of the lasI, lasR, rhlI, rhlR, pqsA and mvfR genes. Rutin also interfered with membrane permeability. Polyphenols could repress antibiotic resistant bacteria. Rutin has shown wide antimicrobial and antibiofilm capacity employing a range of mechanisms that might be used for the development of novel antimicrobials.

Prevalence of tet(X4) in Escherichia coli From Duck Farms in Southeast China

Objectives

Carbapenems, colistin, and tigecycline are critically important antibiotics in clinics. After the global appearance of bla_NDM and mcr mediating the resistance to carbapenems and colistin, respectively, tigecycline becomes the last-resort drug against severe human infections caused by multidrug-resistant bacteria. Recently, a mobile tigecycline resistance gene tet(X4) has been identified in Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii that causes high resistance to tigecycline and other tetracyclines. In this study, the prevalence of tet(X4) in E. coli isolates from duck and goose farms in Southeast China was identified and characterized.

Methods

Feces, soil, sewage, and dust samples were collected from duck and goose farms along with the southeast coast provinces of China. Antimicrobial susceptibility testing and polymerase chain reaction screening were performed to investigate the phenotype and genotype of tigecycline resistance. Conjugation, S1 pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing were used to determine the transferability, genetic location, and the genomic characteristics of tet(X4).

Results

In total, 1,716 samples were collected, and 16 isolates (0.9%) recovered from Guangdong, Shandong, and Jiangsu were positive for tet(X4) gene with tigecycline minimum inhibitory concentrations ≥16 mg/L. Notably, among these tet(X4)-positive E. coil isolates, seven of them were from the environment samples (soil and sewage). PFGE and multilocus sequence typing demonstrated that ST3997 was the most prevalent sequence type (eight isolates, 50%) in Jiangsu province. By conjugation assays, 11 isolates were able to transfer tet(X4) plasmid to E. coli C600 recipient, and these plasmids belonged to IncHI1 and IncX1 detected by sequence analysis. tet(X4) was found adjacent to an insertion sequence ISCR2 downstream and a catD gene upstream for all isolates. In addition, multiple-drug resistance to tigecycline, chlortetracycline, ampicillin, florfenicol, ciprofloxacin, gentamicin, trimethoprim/sulfamethoxazole, and fosfomycin was profiled in most of the tet(X4)-positive isolates.

Conclusion

The identification of tet(X4) harboring E. coli strains in duck farms and their surrounding environment enlarges our knowledge of the variety and prevalence of tigecycline resistance. The prevalence of tet(X4) raises concern for the use of tetracyclines in animal farming, and the tet(X4) gene should be listed as primary gene for resistance surveillance.

The present danger of New Delhi metallo-β-lactamase: a threat to public health

The evolution of antimicrobial-resistant Gram-negative pathogens is a substantial menace to public health sectors, notably in developing countries because of the scarcity of healthcare facilities. New Delhi metallo-β-lactamase (NDM) is a potent β-lactam enzyme able to hydrolyze several available antibiotics. NDM was identified from the clinical isolates of Klebsiella pneumoniae and Escherichia coli from a Swedish patient in New Delhi, India. This enzyme horizontally passed on to various Gram-negative bacteria developing resistance against a variety of antibiotics which cause treatment crucial. These bacteria increase fatality rates and play an integral role in the economic burden. The efficient management of NDM-producing isolates requires the coordination between each healthcare setting in a region. In this review, we present the prevalence of NDM in children, fatality and the economic burden of resistant bacteria, the clonal spread of NDM harboring bacteria and modern techniques for the detection of NDM producing pathogens.

Genotypic and Phenotypic Characterization of Stenotrophomonas maltophilia Strains from a Pediatric Tertiary Care Hospital in Serbia

Background

Stenotrophomonas maltophilia is an environmental bacterium and an opportunistic pathogen usually associated with healthcare-associated infections, which has recently been recognized as a globally multi-drug resistant organism. The aim of this study was genotyping and physiological characterization of Stenotrophomonas maltophilia isolated in a large, tertiary care pediatric hospital in Belgrade, Serbia, hosting the national reference cystic fibrosis (CF) center for pediatric and adult patients.

Methods

We characterized 42 strains of cystic fibrosis (CF) and 46 strains of non-cystic fibrosis (non-CF) origin isolated from 2013 to 2015 in order to investigate their genetic relatedness and phenotypic traits. Genotyping was performed using sequencing of 16S rRNA gene, Pulse Field Gel Electrophoresis (PFGE) and Multi locus sequencing typing (MLST) analysis. Sensitivity to five relevant antimicrobial agents was determined, namely trimethoprim/sulfamethoxazole (TMP/SMX), chloramphenicol, ciprofloxacin, levofloxacin and tetracycline. Surface characteristics, motility, biofilm formation and adhesion to mucin were tested in all strains. Statistical approach was used to determine correlations between obtained results.

Results

Most of the isolates were not genetically related. Six new sequence types were determined. Strains were uniformly sensitive to all tested antimicrobial agents. The majority of isolates (89.8%) were able to form biofilm with almost equal representation in both CF and non-CF strains. Swimming motility was observed in all strains, while none of them exhibited swarming motility. Among strains able to adhere to mucin, no differences between CF and non-CF isolates were observed.

Conclusions

High genetic diversity among isolates implies the absence of clonal spread within the hospital. Positive correlation between motility, biofilm formation and adhesion to mucin was demonstrated. Biofilm formation and motility were more pronounced among non-CF than CF isolates.