Resistant Enterococcus Strains Research Articles

Analysis of molecular epidemiological characteristics and antimicrobial susceptibility of vancomycin-resistant and linezolid-resistant Enterococcus in China

BackgroundThis study investigates the distribution and characteristics of linezolid and vancomycin susceptibilities among Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) and explores the underlying resistance mechanisms.MethodsA total of 2842 Enterococcus clinical isolates from patients were retrospectively collected, and their clinical data were further analyzed. The minimum inhibitory concentrations (MICs) of vancomycin and linezolid were validated by broth dilution method. The resistance genes optrA, cfr, vanA, vanB and vanM were investigated using polymerase chain reaction (PCR). Housekeeping genes and resistance genes were obtianed through whole-genome sequencing (WGS).ResultsOf the 2842 Enterococcus isolates, 88.5% (2516) originated from urine, with E. faecium accounted for 60.1% of these. The vanA gene was identified in 27/28 vancomycin resistant Enterococcus (VRE) isolates, 4 of which carried both vanA and vanM genes. The remaining strain was vanM positive. The optrA gene was identified in all E. faecalis isolates among linezolid resistant Enterococcus (LRE). E. faecium showed a higher multiple antibiotic resistance index (MAR index) compared to E. faecalis. The multi-locus sequence typing (MLST) showed the sequence type of E. faecium mainly belongs to clonal complex (CC) 17, nearly E. faecalis isolates analyzed were differentiated into 7 characteristics of sequence types (STs), among which ST16 of CC16 were the major lineage.ConclusionUrine was the primary source of VRE and LRE isolates in this study. E. faecium showed higher levels of resistance compared to E. faecalis. OptrA gene was detected in 91.6% of LRE, which could explain linezolid resistance, and van genes were detected in all vancomycin resistant Enterococcus strains, while vanA was a key resistance mechanism in VRE identified in this study.

Pyridine-2,6-Dicarboxamide Proligands and their Cu(II)/Zn(II) Complexes Targeting Staphylococcus Aureus for the Attenuation of InVivo Dental Biofilm.

In the pursuit to combat stubborn bacterial infections, particularly those stemming from gram-positive bacteria, this study is an attempt to craft a precision-driven platform characterized by unparalleled selectivity, specificity, and synergistic antimicrobial mechanisms. Leveraging remarkable potential of metalloantibiotics in antimicrobial applications, herein, this work rationally designs, synthesizes, and characterizes a new library of Pyridine-2,6-dicarboxamide ligands and their corresponding transition metal Cu(II)/Zn(II) complexes. The lead compoundL11 demonstrates robust antibacterial properties against Staphylococcus aureus (Minimum Inhibitory Concentration (MIC) = 2-16 µgmL-1), methicillin and vancomycin-resistant S. aureus (MIC = 2-4 µgmL-1) and exhibit superior antibacterial activity when compared to FDA-approved vancomycin, the drug of last resort. Additionally, the compound exhibits notable antimicrobial efficacy against resistant enterococcus strains (MIC = 2-8 µgmL-1). To unravel mechanistic profile, advanced imaging techniques including SEM and AFM are harnessed, collectively suggesting a mechanistic pathway involving cell wall disruption. Live/dead fluorescence studies further confirm efficacy of L11 and its complexes against S. aureus membranes. This translational exploration extends to a rat model, indicating promising in vivo therapeutic potential. Thus, this comprehensive research initiative has capabilities to transcends the confines of this laboratory, heralding a pivotal step toward combatting antibiotic-resistant pathogens and advancing the frontiers of metalloantibiotics-based therapy with a profound clinical implication.

Assessing the Emergence of Resistance in vitro and Invivo: Linezolid Combined with Fosfomycin Against Fosfomycin-Sensitive and Resistant Enterococcus.

PurposeWe aimed to evaluate the synergistic effect of linezolid and fosfomycin on fosfomycin-sensitive and -resistant Enterococcus clinical isolates in vitro and in vivo and whether the emergence of fosfomycin resistance in Enterococcus is associated with changes in strain virulence, from the perspective of fitness cost.MethodsThe synergistic effect of linezolid and fosfomycin was studied via in vitro checkerboard and static time-kill assays, as well as based on the in vivo survival rate and hemolymph load of a Galleria mellonella infection model. Fosfomycin resistance was induced via a stepwise increase in concentration. Changes in the virulence of the strains after drug resistance were investigated using the G. mellonella infection model and reverse transcription quantitative polymerase chain reaction (RT-qPCR). In vitro and in vivo growth curves and competitive experiments were used to study the fitness cost of the strain. Finally, a static time-kill assay was performed to explore the effect of the combined medication.ResultsIn vitro and in vivo data showed that linezolid combined with fosfomycin had a good synergistic effect on Enterococcus treatment. The G. mellonella infection model and RT-qPCR data showed that the virulence of the resistant strains was weakened to varying degrees. A survival curve and competition experimental data showed that this was related to the fitness cost of strains while acquiring resistance and negatively impacted linezolid treatment; however, the combination still showed a good synergistic effect in drug-resistant strains.ConclusionLinezolid combined with fosfomycin had a synergistic effect on both fosfomycin-sensitive and -resistant Enterococcus strains. Strains incur fitness costs as they develop drug resistance, which leads to a decrease in virulence. There is an interaction between fitness cost, virulence, and drug resistance, which indirectly affects drug treatment.

Antimicrobial resistance and genetic relationships of enterococci from siblings and non-siblings Heliconius erato phyllis caterpillars.

BackgroundStudies evaluating bacteria in insects can provide information about host–microorganism–environment interactions. The gut microbial community has a profound effect on different physiological functions of insects. Enterococcus spp. are part of the gut community in humans and other animals, as well as in insects. The presence and antimicrobial resistance profile of enterococci are well studied in different animals; however, data for Heliconius erato phyllis (Lepidoptera: Nymphalidae) do not yet exist. Therefore, the aims of this study were to evaluate the distribution of enterococcal species, their antimicrobial resistance profile and virulence genes, and the genetic relationships between enterococci isolated from fecal samples from sibling and non-sibling H. erato phyllis caterpillars collected from different sites in South Brazil.MethodsThree H. erato phyllis females were captured (two from a forest fragment and one from an urban area), and kept individually in open-air insectaries. Eggs were collected and caterpillars (siblings and non-siblings) were fed daily with Passiflora suberosa leaves. Fecal samples (n = 12) were collected from fifth-instar caterpillars, inoculated in selective medium, and 15 bacterial colonies were randomly selected from each sample. Enterococci were identified by PCR and MALDI-TOF, analyzed by disk diffusion antimicrobial susceptibility tests, and screened for resistance and virulence genes by PCR. The genetic relationships between the strains were determined using pulsed-field gel electrophoresis (PFGE).ResultsA total of 178 enterococci strains were identified: E. casseliflavus (74.15%; n = 132), E. mundtii (21.34%; n = 38), E. faecalis (1.12%; n = 2) and Enterococcus sp. (3.37%; n = 6). High rates of resistance to rifampicin (56%) and erythromycin (31%) were observed; 120 (67.41%) of the isolates showed resistance to at least one antibiotic and six (3.37%) were multidrug-resistant.None of the erythromycin-resistant strains was positive for the erm(B) and msrC genes. The virulence genes esp, ace, and gelE were observed in 35%, 7%, and 1% of the strains, respectively. PFGE separated the enterococci into 22 patterns, four being composed of strains from sibling caterpillars.ConclusionEnterococcus casseliflavus was the dominant species in fecal samples of fifth-instar caterpillars. Resistant enterococci strains may be related to environmental pollution or the resistome. The PFGE analysis showed genetic relationships between some strains, suggesting that the enterococci isolated from fecal samples of the sibling caterpillars might have come from common sources, e.g., via diet (herbivory) and/or vertical transmission (through the egg surface). Further studies will be conducted to better understand the role of Enterococcus in the microbial community of the gastrointestinal tract of these insects, and the mechanisms involved in acquisition and maintenance of enterococci.

Anti-Biofilm and Antimicrobial Activities of Five Edible and Medicinal Macrofungi Samples on Some Biofilm Producing Multi Drug Resistant Enterococcus Strains

It is commonly well-known that biofilms are the predominant mode of bacterial growth, reflected in the clinic observations, where approximately 80% of all bacterial infections are related to biofilms. Bacteria in biofilms are well protected against environmental stresses, antibiotics, disinfectants and the host‘s immune system and are usually extremely difficult to eradicate. Due to common problems caused by biofilms, alternative anti-biofilm strategies must be developed. Enterococcus strains are able to form complex surface-associated communities (biofilms), which contribute to its resistance and persistence in both host and non-host environments, and are especially important in food processing and clinical environments. Enterococcus biofilms showed increased antimicrobial resistance to the most of antibiotics as compared to the planktonic bacteria, which make them difficult to combat. There is an increasing evidence that biofilms are often associated with infectious diseases. Novel anti-biofilm strategies must be designed to include natural bio products instead of common antibiotics. Mushrooms are a nutritionally functional foods and a source of pharmaceuticals having functions such as antitumor, immunomodulating, antioxidant, cardiovascular, anti-hypercholesterolemia, antiviral, antibacterial, anti-parasitic, antifungal, detoxification, hepatoprotective, and antidiabetic. In addition, they have a notable activity against biofilms. In this study, the antimicrobial and anti-biofilm activities of some medicinal and edible mushrooms, namely Morchella angusticeps Peck, Ganoderma lucidum (Curtis) P. Karst., Cerioporus squamosus (Huds.) Quél., Trametes versicolor (L.) Lloyd and Lentinula edodes (Berk.) Singer were screened against multi drug resistant Enterococcus strains. As a result, it was observed that these mushrooms have notable potency to develop alternative medicines to struggle infectious diseases and biofilms.

Effect Oral Administration Ampicillin on the Ecological Balance of rat Enterococcal gut Microbiota.

The main objective of this work is to investigate the impact of oral administration of ampicillin on the ecological balance of enterococci in the intestinal microbiota of rats during a treatment and a post-treatment. The results have showed that the treated animals excreted significantly higher percentages of resistant enterococci compared to the control group (P ≤ 0.05) during the treatment and after the treatment. The most predominant species selected after the treatment began were Enterococcus faecium. The MICs for ampicillin for all isolates of E. faecium were 32 to 64µg/mL, with the exception of two strains (TR1LBMB, TR5LBMB), were found to be highly resistant (MICs ≥ 128µg/mL). Quantification of ampicillin in faeces by the RT-HPLC showed that the significant increase in the number of ampicillin-resistant enterococci was associated with the gradual accumulation of high levels of unabsorbed ampicillin in the faeces. Our results suggest that ampicillin treatment can now be understood as a side effect contributing to the increase in the number of resistant Enterococcus strains, particularly E. faecium strains, recognized as important nosocomial pathogens.

Glycyrrhizic Acid Decreases Gentamicin-Resistance in Vancomycin-Resistant Enterococci.

The resistance of commensal bacteria against first and second line antibiotics has reached an alarming level in many parts of the world and endangers the effective treatment of infectious diseases. Particularly vancomycin-resistant Enterococcus faecium represents an increasing clinical problem in the treatment of infectious diseases and hinders adequate antibiotic stewardship. In consideration of the lack of novel antibiotic compounds, the development of resistance-modifying agents, however, can mitigate the spread of bacterial drug resistance and might possibly extend the useful application indices of an existing licensed antibiotic. Given that saponins modify the local chemical environment at cell membranes and might modify the uptake or mode of action of antibiotics in bacteria, we investigated the influence of the triterpenoid saponin glycyrrhizic acid of Glycyrrhiza glabra on the susceptibility of vancomycin-resistant enterococci against the aminoglycoside antibiotic gentamicin in 47 clinical isolates by applying the checkerboard method. The fractional inhibitory concentration indices values were determined between 0.016 and ≤ 0.5 (synergy is accepted with values ≤ 0.5). Glycyrrhizic acid at the subinhibitory concentration of 2.4 mM was found to reduce the minimal inhibitory concentration of gentamicin in intrinsically resistant E. faecium strains down to 6.25 % of the minimal inhibitory concentration of gentamicin alone, whereas relatively low concentrations of glycyrrhizic acid (18 µM) resulted in increased susceptibilities for some E. faecium isolates to gentamicin. In conclusion, our study points towards a therapeutic potential of glycyrrhizic acid in co-application with gentamicin for defined local bacterial infections caused by vancomycin resistant Enterococcus strains.

Most Commonly Isolated Bacteria in Urine and their In Vitro Sensitivity to Antibiotics in Men with Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms commonly affect older men. Men with BPH in Podgorica in almost half (47.5%) cases have positive urine culture, out of which 14.2% have polyinfection. Urinary tract infections are most common in the age group 71 to 80 years. Although both groups of men (with and without BPH) are more prone to gram-negative bacterial infections of the urinary tract, K. pneumoniae is significantly more common in men with BPH compared with men without BPH. The results indicate that treatment of men with BPH is much more complex than in men without BPH due to the fact that in the treatment, a number of strains are resistant to levofloxacin (resistance of gram-negative bacteria to levofloxacin at the level of 80.4%, with 89.7% of resistant strains of K. pneumoniae and 73.3% of E. coli strains, as well as resistance of gram-positive bacteria at level of 24.8%, with resistant strains of enterococci in 64.7% of the strains) and Ž²-lactam antibiotics (53.4% of isolated gram-negative bacteria synthesize ESBL enzymes out of which K. pneumoniae in up to 89.7% of the strains). Also, men with BPH have multi drug resistant strains in 53.1% of gram-positive bacteria and 79.7% of gram-negative bacteria. Carbapenems still represent a reserve group of drugs that have a good therapeutic effect in 93.2% of urinary tract infections in men with BPH.

Gastrointestinal Colonization with Vancomycin-Resistant Enterococci In Hospitalized and Outpatients.

BACKGROUND:The incidence of infection and intestinal colonization with vancomycin resistant enterococci (VRE) is increasing in many countries in the last decade. Concerning the difficult antimicrobial treatment of infections caused by VRE, decreasing the incidence and prevalence of these infections is an important factor in VRE-induced morbidity and mortality control.AIM:To determine the prevalence of gastrointestinal colonization with vancomycin resistant enterococci in hospitalized and outpatients, and to determine the genetic base of the vancomycin resistance in VRE isolates.MATERIAL AND METHODS:Seven hundred and eighty stool specimens were investigated for the gastrointestinal carriage of vancomycin-resistant enterococci (VRE). Susceptibility to vancomycin was tested in all isolates by disk-diffusion test and E-test (AB Biodisk, Sweden). Determined vancomycin resistant enterococci were than tested for detection of vanA, vanB and vanC genes by PCR.RESULTS:Vancomycin resistant strains of enterococci were isolated from 46 (16.1 %) of the 285 hospitalized patients and 5 (7.7 %) of the 65 patients living in the community (p < 0.05). The most of the highly resistant enterococci strains to vancomycin (95.2 %), were identified as E. faecium. Minimal inhibitory concentrations (MICs) to vancomycin in all 39 vanA genotypes of E. faecium and two vanA genotypes of E. fecalis were > 256 μg/ml. Three vanB genotypes of E. faecium and one vanB genotype of E. faecalis had MICs of 32 μg/ml. All six vanC genotypes of E. gallinarum had MICs of 8 μg/ml. All vanA genotypes of VRE were highly resistant to vancomycin, with MICs above 256 μg/ml. Three vanB genotypes of VR E. faecium and one VR E. fecalis were resistant, with MICs 32 μg/ml. vanC genotypes of VR E. gallinarum were intermediate resistant to vancomycin with MICs of 8 μg/ml.CONCLUSIONS:The prevalence of vancomycin resistant enterococci in Republic of Macedonia was 2-fold higher in hospitalized than in outpatients. VanA genotype was dominant in isolates of E. faecium and it was highly associated with the MIC values above the 256 μg/ml. Since most of the enterococcal infections are endogenous, there is a need for screening the colonization of patient’s intestinal flora with VRE at the hospital entry. Identification and genotyping of faecal enterococci, together with their susceptibility testing to vancomycin, could be useful marker for the infection control.

Erreger- und Resistenzspektrum einer chirurgischen ITS im systematischen 10-Jahres-Vergleich 1996-2005 im Rahmen des mikrobiologischen Routinemonitorings

Knowledge on potentially pathogenic microbes including characteristics of their antibiotic resistance in septic patients as well as on the ward- and department-specific microbial spectrum can be considered essential for an efficient initiation of an adequate antimicrobial treatment, which turns out to become pivotal for patient outcome. Permanent changes in microbial patterns and antibiotic resistance can only be identified by a continuous investigation of various microbiological specimens. Based on the retrospective evaluation of prospectively collected data on microbiological investigations of the surgical ICU in 1996, 2002, 2004 and 2005, the short- and long-term changes by trend of microbial spectrum and antibiotic resistance following reorganisation and restructuring of the University Hospital from the more traditional pavillon-based system to a multidisciplinary complex building in 2003 were investigated. Twice a week, routine microbiological testing of blood and urinary cultures as well as swabs from wound areas and endotracheal swabs were initiated in septic patients (suspect, manifestation) or in case of their clinical impairment. The microbial spectrum was sub-divided according to Gram-staining (Gram-positive/ -negative), various species and fungi with descriptive absolute and relative data values. -Various groups and time periods were statistically compared using χ² test as appropriate. P values < 0.05 were considered statistically significant. In total (n (Total) = 4 899), microbiological testing resulted in the detection of microbes in 699 and 833 blood and urinary cultures (14.3 % and 17 %, respectively) as well as 1 232 wound swabs (25.1 %) together with 2 135 samples from the endotracheal sites (43.6 %). During the short- (2002 vs. 2004) and long-term analyses (1996 vs. 2005), the proportion of Gram-positive microbes increased. Al-though Gram-positive bacteria can be considered the most frequent microbes for bacteriemia, there was a shift onto urinary and wound infections as well as pneumonias through the observation period. Despite the decreasing incidence of Enterococcus and the consistent proportion of MRSA, the increase of resistant Enterococcus strains (0 % vs. 43.2 %; P < 0.05) is critical. However, in the Gram-negative microbial spectrum there was an increase of the bacteraemia rate but a fall of the detection rate in wound and endotracheal swabs. In parallel, an increase of the detection rate of E. coli in blood (6.5 % vs. 45.5 %; P < 0.05) and endotracheal swabs (9.2 % vs. 16.2 %; P < 0.05) is associated with an increase of multiresistant Enterobacteriaceae strains (0 % vs. 30.7 %; P < 0.05). The portion of multiresistant strains of Pseudomonas with 31 % stayed the same through the 10-year time period. While Candida-based colonisation showed a decreased incidence (25 % vs. 15 %; P < 0.05) during the whole investigation period, there was a relative rise in the frequency of candidemia. ICU relocation from the pavillon-based system to a new complex clinic building was not associated with any significant alteration of the microbial spectrum on the surgical ICU. Increasing incidences of resistant Enterococcus and Gram-negative problematic microbes may indicate a general spread of multi-resistant microbes under the steady selecting pressure of a not always adequately initiated antibiotic / antimicrobial therapeutic regimen and underline the required but specific and selected microbiological screening.

Aminoglycoside-modifying enzymes in high-level streptomycin and gentamicin resistant Enterococcus spp. in Spain

Aminoglycoside resistance was evaluated in 690 enterococcus strains isolated from different clinical sources originating from patients at the University Clinic Hospital of Zaragoza (Spain). The enterococci obtained from clinically significant samples (blood, urine, or exudates) showed more high-level resistance to gentamicin and streptomycin (65 and 42%, respectively) than those isolated from faecal samples (49 and 23%, respectively). Aminoglycoside-modifying enzymes (AME) from 119 of these high-level gentamicin and streptomycin resistant enterococcus strains were studied. The most frequent AMEs found were APH(3′) and AAC(6′)-APH(2″). More than one enzyme was detected in 71% of the strains (four different enzymes in 5% of the strains). Three Enterococcus faecalis strains had ANT(4′)(4″) enzymatic activity. Different enzymatic expressions of the bifunctional enzyme AAC(6′)-APH(2″) were demonstrated in strains in which the complete aac(6′)-aph(2″ ) gene was detected by PCR and hybridization: (i) AAC(6′)+APH(2″) activity; (ii) AAC(6′) only; (iii) APH(2″) only; and (iv) no activity of AAC(6′) or APH(2″).

Treatment of experimental endocarditis caused by multidrug resistant Enterococcus faecium with ramoplanin and penicillin.

Antibiotic resistant strains of enterococci are being isolated with increasing frequency. Effective treatment of infections caused by Enterococcus faecium resistant to ampicillin, vancomycin and aminoglycosides has not been established. We studied the activity of ramoplanin, a new lipoglycopeptide antibiotic, against two strains of multidrug resistant E. faecium. In time kill studies, ramoplanin was bactericidal against both strains, but not in the presence of 50% serum. The combination of ramoplanin and penicillin was bactericidal even in the presence of serum. In rabbits with experimental endocarditis neither penicillin nor ramoplanin significantly reduced vegetation colony counts when given alone, although ramoplanin significantly reduced spleen and kidney bacterial counts of both strains. The combination of ramoplanin plus penicillin resulted in a significant reduction of vegetation bacterial counts (-3.2 and -3.7 log10 cfu/g for strains VA3 and MMC3, respectively, P < 0.01). All spleen cultures and 9 out of 10 kidney cultures from each strain were sterile following combination therapy. While ramoplanin will not be available for parenteral therapy, further research into the development of other lipoglycopeptide antibiotics is warranted.