scholarly journals Linezolid resistance genes in enterococci isolated from sediment and zooplankton in two Italian coastal areas

2021 ◽  
Author(s):  
Simona Fioriti ◽  
Sonia Nina Coccitto ◽  
Nicholas Cedraro ◽  
Serena Simoni ◽  
Gianluca Morroni ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Urban Areas ◽  
Acquired Resistance ◽  
Coastal Areas ◽  
Resistant Bacteria ◽  
Gram Positive Bacteria ◽  
Marine Samples ◽  
Linezolid Resistance ◽  
Environmental Setting ◽  
Severe Infections

Linezolid is a last resort antibiotic for the treatment of severe infections caused by multi-resistant Gram-positives; although linezolid resistance remains uncommon, the number of linezolid-resistant enterococci has increased during recent years due to worldwide spread of acquired resistance genes (cfr, optrA and poxtA) in clinical, animal and environmental setting. In this study we investigated the occurrence of linezolid-resistant enterococci in marine samples from two coastal areas in Italy. Isolates grown on florfenicol-supplemented Slanetz-Bartley were investigated for their carriage of optrA, poxtA and cfr genes: optrA was found in one E. faecalis, poxtA in three E. faecium and two E. hirae and cfr was not found. Two of the three poxtA-carrying E. faecium and the two E. hirae showed related PFGE profiles. Two E. faecium belonged to the new ST1710, which clustered in the clonal complex CC94, encompassing nosocomial strains. S1-PFGE/hybridization assays showed a double (chromosome and plasmid) location of poxtA and plasmid location of optrA. WGS revealed that poxtA was contained in a Tn6657-like element carried by two plasmids (pEfm-EF3 and pEh-GE2) of similar size, found in different species, and that poxtA were flanked by two copies of IS1216 in both plasmids. In mating experiments all but one (E. faecalis EN3) strains were able to transfer the poxtA gene to E. faecium 64/3. The occurrence of linezolid resistance genes in enterococci from marine samples is of great concern and highlights the need to improve practices aimed at limiting the transmission of linezolid resistant strains to humans from the environmental reservoirs. Importance Linezolid is one of the few antimicrobials available to treat severe infections due to drug-resistant Gram-positive bacteria, thus the emergence of linezolid-resistant enterococci carrying transferable resistance determinants is of great concern for public health. Linezolid resistance genes (cfr, optrA and poxtA), often plasmid located, can be transmitted via horizontal gene transfer and have the potential to spread globally. This study highlights the first detection of enterococci carrying linezolid resistance genes from sediment and zooplankton samples in two coastal urban areas in Italy. The presence of clinically relevant resistant bacteria, such as linezolid-resistant enterococci, in marine environment could reflect their spillover from human and/or animal reservoirs and could indicate that also coastal seawaters could represent a source of these resistance genes.

scholarly journals Population Structure and Resistance Genes in Antibiotic-Resistant Bacteria from a Remote Community with Minimal Antibiotic Exposure

2006 ◽  
Vol 51 (4) ◽  
pp. 1179-1184 ◽  
Author(s):  
Lucia Pallecchi ◽  
Chiara Lucchetti ◽  
Alessandro Bartoloni ◽  
Filippo Bartalesi ◽  
Antonia Mantella ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Acquired Resistance ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Antibiotic Exposure ◽  
Remote Community ◽  
E Coli ◽  
Class 1 ◽  
Phylogenetic Grouping ◽  
Group A

ABSTRACT In a previous study, we detected unexpectedly high levels of acquired antibiotic resistance in commensal Escherichia coli isolates from a remote Guaraní Indian (Bolivia) community with very low levels of antibiotic exposure and limited exchanges with the exterior. Here we analyzed the structure of the resistant E. coli population from that community and the resistance mechanisms. The E. coli population (113 isolates from 72 inhabitants) showed a high degree of genetic heterogeneity, as evidenced by phylogenetic grouping (77% group A, 10% group B1, 8% group D, 5% group B2) and genotyping by randomly amplified polymorphic DNA (RAPD) analysis (44 different RAPD types). The acquired resistance genes were always of the same types as those found in antibiotic-exposed settings [bla TEM, bla PSE-1, catI, cmlA6, tet(A), tet(B), dfrA1, dfrA7, dfrA8, dfrA17, sul1, sul2, aphA1, aadA1, aadA2, aadA5, aadB, and sat-1]. Class 1 and class 2 integrons were found in 12% and 4% of the isolates, respectively, and harbored arrays of gene cassettes similar to those already described. The cotransferability of multiple-resistance traits was observed from selected isolates and was found to be associated with resistance conjugative plasmids of the F, P, and N types. Overall, these data suggest that the resistance observed in this remote community is likely the consequence of the dissemination of resistant bacteria and resistance genes from antibiotic-exposed settings (rather than of an independent in situ selection) which involved both the clonal expansion of resistant strains and the horizontal transfer/recombination of mobile genetic elements harboring resistance genes.

scholarly journals In vitro Activity of Contezolid Against Methicillin-Resistant Staphylococcus aureus, Vancomycin-Resistant Enterococcus, and Strains With Linezolid Resistance Genes From China

2021 ◽  
Vol 12 ◽  
Author(s):  
Siheng Wang ◽  
Chang Cai ◽  
Yingbo Shen ◽  
Chengtao Sun ◽  
Qingxin Shi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Resistance Genes ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Linezolid Resistance ◽  
Staphylococcus Capitis ◽  
Potential Benefits ◽  
Vancomycin Resistant ◽  
Better Than

Contezolid is a novel oxazolidinone, which exhibits potent activity against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and penicillin-resistant Streptococcus pneumoniae (PRSP). In this study, the in vitro activity of contezolid was compared with linezolid (LZD), tigecycline (TGC), teicoplanin (TEC), vancomycin (VA), daptomycin (DAP), and florfenicol (FFC) against MRSA and VRE strains isolated from China. Contezolid revealed considerable activity against MRSA and VRE isolates with MIC90 values of 0.5 and 1.0 μg/mL, respectively. For VRE strains with different resistance genotypes, including vanA- and vanM-type strains, contezolid did not exhibit significantly differential antibacterial activity. Furthermore, the antimicrobial activity of contezolid is similar to or slightly better than that of linezolid against MRSA and VRE strains. Subsequently, the activity of contezolid was tested against strains carrying linezolid resistance genes, including Staphylococcus capitis carrying cfr gene and Enterococcus faecalis carrying optrA gene. The results showed that contezolid exhibited similar antimicrobial efficacy to linezolid against strains with linezolid resistance genes. In general, contezolid may have potential benefits to treat the infections caused by MRSA and VRE pathogens.

Renaissance of vancomycin: approaches for breaking antibiotic resistance in multidrug-resistant bacteria

2020 ◽  
Vol 66 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Eric Mühlberg ◽  
Florian Umstätter ◽  
Christian Kleist ◽  
Cornelius Domhan ◽  
Walter Mier ◽  
...  
Keyword(s):  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Multidrug Resistant Bacteria ◽  
Structural Modifications ◽  
Gram Positive Bacteria ◽  
Vancomycin Resistant Enterococci ◽  
New Antibiotics ◽  
Life Threatening ◽  
Severe Infections ◽  
Vancomycin Resistant

The emergence of multidrug-resistant bacteria demands innovations in the development of new antibiotics. For decades, the glycopeptide antibiotic vancomycin has been considered as the “last resort” treatment of severe infections caused by Gram-positive bacteria. Since the discovery of the first vancomycin-resistant enterococci strains in the late 1980s, the number of resistances has been steadily rising, with often life-threatening consequences. As an alternative to the generation of completely new substances, novel approaches focus on structural modifications of established antibiotics such as vancomycin to overcome these resistances. Here, we provide an overview of several promising modifications of vancomycin to restore its efficacy against vancomycin-resistant enterococci.

scholarly journals Comparison of the In Vitro Efficacies of Moxifloxacin and Amoxicillin against Listeria monocytogenes

2008 ◽  
Vol 52 (5) ◽  
pp. 1697-1702 ◽  
Author(s):  
S. Grayo ◽  
O. Join-Lambert ◽  
M. C. Desroches ◽  
A. Le Monnier
Keyword(s):  
Listeria Monocytogenes ◽  
Bactericidal Effect ◽  
Cross Resistance ◽  
Resistant Bacteria ◽  
Gram Positive Bacteria ◽  
Severe Infections ◽  
Potential Alternative ◽  
Kill Curve ◽  
Time Kill

ABSTRACT Listeria monocytogenes is a facultative intracellular bacterium that causes severe infections associated with a high mortality rate. Moxifloxacin presents extended activity against gram-positive bacteria and has recently been suggested to be a potential alternative in the treatment of listeriosis. We evaluated the in vitro efficacy of moxifloxacin against L. monocytogenes using a combination of epidemiological and experimental approaches. The median MIC of moxifloxacin for a large collection of L. monocytogenes strains of various origins (human, food, and environment) was 0.5 μg/ml (MIC range, 0.064 to 1 μg/ml). No differences were observed, irrespective of the origin of the strains. Moreover, no cross-resistance with fluoroquinolones was detected in strains that have been reported to be resistant to ciprofloxacin. The in vitro activities of moxifloxacin and amoxicillin were compared by time-kill curve and inhibition of intracellular growth experiments by using a model of bone marrow-derived mouse macrophages infected by L. monocytogenes EGDe. Both moxifloxacin and amoxicillin were bactericidal in broth against extracellular forms of L. monocytogenes. However, moxifloxacin acted much more rapidly, beginning to exert its effects in the first 3 h and achieving complete broth sterilization within 24 h of incubation. Moxifloxacin has a rapid bactericidal effect against intracellular reservoirs of bacteria, whereas amoxicillin is only bacteriostatic and appears to prevent cellular lysis and the subsequent bacterial spreading to adjacent cells. No resistant bacteria were selected during the in vitro experiments. Taken together, our results suggest that moxifloxacin is an interesting alternative to the reference treatment, combining rapid and bactericidal activity, even against intracellular bacteria.

scholarly journals Current perspectives on glycopeptide resistance.

1995 ◽  
Vol 8 (4) ◽  
pp. 585-615 ◽  
Author(s):  
N Woodford ◽  
A P Johnson ◽  
D Morrison ◽  
D C Speller
Keyword(s):  
Antimicrobial Therapy ◽  
Molecular Typing ◽  
Acquired Resistance ◽  
Resistant Bacteria ◽  
Glycopeptide Antibiotics ◽  
Glycopeptide Resistance ◽  
Gram Positive Bacteria ◽  
Reliable Detection ◽  
Typing Methods ◽  
Sporadic Cases

In the last 5 years, clinical isolates of gram-positive bacteria with intrinsic or acquired resistance to glycopeptide antibiotics have been encountered increasingly. In many of these isolates, resistance arises from an alteration of the antibiotic target site, with the terminal D-alanyl-D-alanine moiety of peptidoglycan precursors being replaced by groups that do not bind glycopeptides. Although the criteria for defining resistance have been revised frequently, the reliable detection of low-level glycopeptide resistance remains problematic and is influenced by the method chosen. Glycopeptide-resistant enterococci have emerged as a particular problem in hospitals, where in addition to sporadic cases, clusters of infections with evidence of interpatient spread have occurred. Studies using molecular typing methods have implicated colonization of patients, staff carriage, and environmental contamination in the dissemination of these bacteria. Choice of antimicrobial therapy for infections caused by glycopeptide-resistant bacteria may be complicated by resistance to other antibiotics. Severe therapeutic difficulties are being encountered among patients infected with enterococci, with some infections being untreatable with currently available antibiotics.

scholarly journals Antibacterial Activity of Fluorobenzoylthiosemicarbazides and Their Cyclic Analogues with 1,2,4-Triazole Scaffold

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 170
Author(s):  
Urszula Kosikowska ◽  
Monika Wujec ◽  
Nazar Trotsko ◽  
Wojciech Płonka ◽  
Piotr Paneth ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Resistant Bacteria ◽  
Binding Affinities ◽  
Substitution Pattern ◽  
Minimal Inhibitory Concentrations ◽  
Gram Positive Bacteria ◽  
Structure Activity ◽  
Drug Resistant Bacteria ◽  
Reference Strains

The development of drug-resistant bacteria is currently one of the major challenges in medicine. Therefore, the discovery of novel lead structures for the design of antibacterial drugs is urgently needed. In this structure–activity relationship study, a library of ortho-, meta-, and para-fluorobenzoylthiosemicarbazides, and their cyclic analogues with 1,2,4-triazole scaffold, was created and tested for antibacterial activity against Gram-positive bacteria strains. While all tested 1,2,4-triazoles were devoid of potent activity, the antibacterial response of the thiosemicarbazides was highly dependent on substitution pattern at the N4 aryl position. The optimum activity for these compounds was found for trifluoromethyl derivatives such as 15a, 15b, and 16b, which were active against both the reference strains panel, and pathogenic methicillin-sensitive and methicillin-resistant Staphylococcus aureus clinical isolates at minimal inhibitory concentrations (MICs) ranging from 7.82 to 31.25 μg/mL. Based on the binding affinities obtained from docking, the conclusion can be reached that fluorobenzoylthiosemicarbazides can be considered as potential allosteric d-alanyl-d-alanine ligase inhibitors.

scholarly journals First Case of Staphylococci Carrying Linezolid Resistance Genes from Laryngological Infections in Poland

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 335
Author(s):  
Michał Michalik ◽  
Maja Kosecka-Strojek ◽  
Mariola Wolska ◽  
Alfred Samet ◽  
Adrianna Podbielska-Kubera ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Ribosomal Proteins ◽  
Multidrug Resistant ◽  
Aureus Strain ◽  
Coagulase Negative Staphylococci ◽  
Spa Typing ◽  
Linezolid Resistance ◽  
First Case ◽  
Resistance Patterns

Linezolid is currently used to treat infections caused by multidrug-resistant Gram-positive cocci. Both linezolid-resistant S. aureus (LRSA) and coagulase-negative staphylococci (CoNS) strains have been collected worldwide. Two isolates carrying linezolid resistance genes were recovered from laryngological patients and characterized by determining their antimicrobial resistance patterns and using molecular methods such as spa typing, MLST, SCCmec typing, detection of virulence genes and ica operon expression, and analysis of antimicrobial resistance determinants. Both isolates were multidrug resistant, including resistance to methicillin. The S. aureus strain was identified as ST-398/t4474/SCCmec IVe, harboring adhesin, hemolysin genes, and the ica operon. The S. haemolyticus strain was identified as ST-42/mecA-positive and harbored hemolysin genes. Linezolid resistance in S. aureus strain was associated with the mutations in the ribosomal proteins L3 and L4, and in S. haemolyticus, resistance was associated with the presence of cfr gene. Moreover, S. aureus strain harbored optrA and poxtA genes. We identified the first case of staphylococci carrying linezolid resistance genes from patients with chronic sinusitis in Poland. Since both S. aureus and CoNS are the most common etiological factors in laryngological infections, monitoring of such infections combined with surveillance and infection prevention programs is important to decrease the number of linezolid-resistant staphylococcal strains.

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