Search

A classical ayurvedic polyherbal formulation namely Triphala was assessed for its anti-pathogenic potential against five different pathogenic bacteria. Virulence of four of them towards the model host Caenorhabditis elegans was attenuated (by 18-45%) owing to pre-treatment with Triphala (≤20 µg/ml). Triphala could also exert significant therapeutic effect on worms already infected with Chromobacterium violaceum , Serratia marcescens or Staphylococcus aureus . Prophylactic use of Triphala allowed worms to score 14-41% better survival in face of subsequent pathogen challenge. Repeated exposure to this formulation induced resistance in S. marcescens , but not in P. aeruginosa . It also exerted a post-extract effect (PEE) on three of the test pathogens. Triphala was able to modulate production of quorum sensing (QS)-regulated pigments in three of the multidrug-resistant gram-negative test bacteria. Haemolytic activity of S. aureus was heavily inhibited under the influence of this formulation. P. aeruginosa's lysozyme-susceptibility was found to increase by ~25-43% upon Triphala -pretreatment. These results validate therapeutic potential of one of the most widely used polyherbal ayurvedic formulations called Triphala ., Competing Interests: No competing interests were disclosed., (Copyright: © 2019 Patel H et al.)

Chromosomal AmpC β-lactamase induction by several types of β-lactams has been reported, but not enough data are available on DHA-1 β-lactamase, a plasmid-mediated AmpC β-lactamase. Therefore, we evaluated the DHA-1 β-lactamase induction by various antibiotics including piperacillin/tazobactam (PIP/TZB) in this study. Six strains (Enterobacter cloacae 2 strains, Citrobacter freundii 1 strain, Serratia marcescens 2 strain, and Morganella morganii 1 strain) possessing chromosomal inducible AmpC β-lactamase were used as controls. Four strains (Escherichia coli 2 strains, Klebsiella pneumoniae 1 strain, and C. koseri 1 strain) possessing DHA-1 β-lactamase were used. The β-lactamase activities were determined by a spectrophotometer using nitrocefin. β-lactamase induction by PIP, PIP/TZB was not observed in any strains and β-lactamase induction by third- and fourth-generation cephems was not observed in most strains. The induction ratios of the chromosomal AmpC β-lactamase in the reference group by PIP/TZB were <1.51, and those of the DHA-1 β-lactamase were <1.36, except for K. pneumoniae Rkp2004 (2.22). The β-lactamase induction by first- and second-generation cephems, flomoxef, and carbapenem differed in each strain. Cefmetazole (CMZ) strongly induced β-lactamase. This study demonstrated that the induction of DHA-1 β-lactamase was similar to that of chromosomal AmpC using various Enterobacteriaceae, although the induction of β-lactamase in both groups by PIP/TZB was low. We also reported that the induction of PIP/TZB, a β-lactamase inhibitor combination antibiotic, against various AmpC-producing Enterobacteriaceae, including DHA-1 producers, was low., Competing Interests: The authors have declared that no competing interests exist.

The present study aimed to further clarify the genetic mechanisms responsible for the antimicrobial resistance of Serratia marcescens (S. marcescens) using RNA sequencing. Three drug‑susceptible S. marcescens strains (named MYQT1, MYQT2, and MYQT3) and three multidrug‑resistant S. marcescens strains (named MYQT4, MYQT5, and MYQT6) were isolated from six different patients and subjected to RNA sequencing. Differentially expressed genes (DEGs) between the multidrug‑resistant S. marcescens strains and drug‑susceptible strains were screened and compared, followed by functional enrichment analysis. In addition, a protein‑protein interaction (PPI) network was constructed, and significant modules were extracted from it. Genes enriched in the significant modules were subjected to further enrichment analysis. MYQT3 had very a different expression pattern from MYQT1 and MYQT2, and thus, MYQT3 was excluded from the following analysis. A total of 225 DEGs were identified, of which SMDB11&#95;RS09300 (GTP cyclohydrolase FolE2) was the most significantly upregulated with a log2 FC of 6.4; these DEGs were enriched in different GO terms, including hydrogen sulfide biosynthetic process, sulfur compound transmembrane transporter activity, and ABC transporter complex. Additionally, several genes were identified to be important genes in the PPI network, including SMDB11&#95;RS17755 (upregulated; glutamate synthase large subunit), SMDB11&#95;RS00590 (upregulated; sulfite reductase subunit α), and SMDB11&#95;RS04505 (upregulated; cystathionine β‑synthase). Thus, SMDB11&#95;RS09300, SMDB11&#95;RS17755, SMDB11&#95;RS00590, and SMDB11&#95;RS04505 may play significant roles in the antimicrobial resistance of S. marcescens by participating in folate metabolism or the integrity of cell membranes. However, further experiments are required to clarify these findings.

In this study, we present the genome sequence of Serratia marcescens SM03, recovered from a human gut in India. The final assembly consists of 26 scaffolds (4620 coding DNA sequences, 5.08 Mb, 59.6% G + C ratio) and 79 tRNA genes. Analysis identified novel genes associated with lactose utilization, virulence, P-loop GTPases involved in urease production, CFA/I fimbriae apparatus and Yersinia - type CRISPR proteins. Antibiotic susceptibility testing indicated drug tolerant phenotype and inhibition assays demonstrated involvement of extrusion in resistance. Presence of enzymes SRT-2, AAC(6')-Ic, with additional Ybh transporter and EamA-like efflux pumps signifies the genetic plasticity observed in S. marcescens SM03., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: Plant products are sources for drug development against multidrug resistant bacteria., Methods: The antimicrobial activity of Origanum vulgare L. essential oil (OVeo) against carbapenem-resistant strains was assessed by disk-diffusion, microdilution (REMA-Resazurin Microtiter Assay), and time kill assays., Results: Carbapenemase production was confirmed for all strains. OVeo exhibited a minimum inhibitory concentration of 0.059% v/v for Klebsiella pneumoniae and Serratia marcescens, and of 0.015 % v/v for Acinetobacter baumannii. A decrease in cell count was observed after a 4 h treatment., Conclusions: OVeo antimicrobial effect was rapid and consistent, making it a candidate for developing alternative therapeutic options against carbapenem-resistant strains.

Capsicum peppers have not been investigated as sources of quorum sensing (QS) inhibitors. This study aimed to identify compounds in pimenta-malagueta (Capsicum frutescens) and red pepper (Capsicum annuum) extracts and to evaluate their effect on violacein production in Chromobacterium violaceum ATCC 12472 and C. violaceum CV026, as well as biofilm formation (BF) in Pseudomonas aeruginosa PAO1 and Serratia marcescens MG1. Among the extracts, pimenta-malagueta methanolic extract (PMME) was chosen because it contained capsaicin, dihydrocapsaicin, and luteolin in greater amount than the other extracts. In general, PMME partially inhibited bacterial growth at 2.5 and 5.0 mg/mL, as well as capsaicin at 100 µg/mL and luteolin at 62.5, 125, and 250 µg/mL. At lower concentrations, PMME and luteolin reduced violacein production in C. violaceum ATCC 12472 without affecting growth, a result that was not observed with capsaicin. We show that violacein inhibition by PMME is likely due to luteolin. In silico docking evaluation showed that luteolin binds to the CviR QS regulator. Crystal violet staining and confocal microscopy revealed that BF was increased by PMME and capsaicin, being remarkably superior for P. aeruginosa PAO1 at 30 °C. Capsaicin is not an effective QS inhibitor, while luteolin should be further investigated for its potential effects in QS regulated phenotypes. PRACTICAL APPLICATION: Quorum sensing (QS) is a form of bacterial communication targeted for studies aiming to inhibit bacterial virulence. QS regulates phenotypes that influence microbial activities across many areas, including Food Science. Capsicum frutescens is a type of chili pepper consumed in Brazil, rich in bioactive compounds such as capsaicin (which gives its pungency) and luteolin (a phenolic compound). We show that C. frutescens extract and luteolin inhibit QS in a model bacterium, along with the possible molecular mechanism of inhibition. Capsaicin did not inhibit QS neither biofilm formation. Luteolin should be further investigated for its QS inhibition properties and biotechnological applications., (© 2019 Institute of Food Technologists®.)

N -acyl-homoserine lactone quorum sensing (AHL-QS) has been shown to regulate many physiological behaviors in Serratia marcescens MG1. In the current study, the effects of AHL-QS on the biosynthesis of acid and neutral products by S . marcescens MG1 and its isogenic ∆swrI with or without supplementing exogenous N -hexanoyl-L-homoserine lactone (C 6 -HSL) were systematically investigated. The results showed that swrI disruption resulted in rapid pH drops from 7.0 to 4.8, which could be restored to wild type by supplementing C 6 -HSL. Furthermore, fermentation product analysis indicated that ∆swrI could lead to obvious accumulation for acidogenesis products such as lactic acid and succinic acid, especially excess acetic acid (2.27 g/l) produced at the early stage of fermentation, whereas solventogenesis products by ∆swrI appeared to noticeably decrease by an approximate 30% for acetoin during 32-48 h and by an approximate 20% for 2,3-butanediol during 24-40 h, when compared to those by wild type. Interestingly, the excess acetic acid produced could be removed in an AHL-QS-independent manner. Subsequently, quantitative real-time PCR was used to determine the mRNA expression levels of genes responsible for acidogenesis and solventogenesis and showed consistent results with those of product synthesis. Finally, by close examination of promoter regions of the analyzed genes, four putative luxI box-like motifs were found upstream of genes encoding acetyl-CoA synthase, lactate dehydrogenase, α-acetolactate decarboxylase, and Lys-like regulator. The information from this study provides a novel insight into the roles played by AHL-QS in switching from acidogenesis to solventogenesis in S . marcescens MG1.

Susceptibility of ceftazidime-avibactam and in vitro synergy with meropenem were investigated using disk approximation and time-kill assays against 11 multiresistant Acinetobacter baumannii isolates harboring oxacillinases and 5 Serratia marcescens isolates carrying bla KPC-2 Ceftazidime-avibactam was very active and synergistic with meropenem against multiresistant S. marcescens isolates. On the other hand, only the A. baumannii isolates coharboring bla OXA-23 and bla OXA-117 displayed synergy. The disk approximation technique presented good sensitivity for synergism in S. marcescens infection., (Copyright © 2019 American Society for Microbiology.)

We investigated the role of the resistance-nodulation-cell division superfamily (RND) efflux system on intrinsic multidrug resistance in Serratia marcescens. We identified eight putative RND efflux system genes in the S. marcescens Db10 genome that included the previously characterized systems, sdeXY, sdeAB, and sdeCDE. Six out of the eight genes conferred multidrug resistance on KAM32, a drug hypersensitive strain of Escherichia coli. Five out of the eight genes conferred resistance to benzalkonium, suggesting the importance of RND efflux systems in biocide resistance in S. marcescens. The energy-dependent efflux activities of five of the pumps were examined using a rhodamine 6 G efflux assay. When expressed in the tolC-deficient strain of E. coli, KAM43, none of the genes conferred resistance on E. coli. When hasF, encoding the S. marcescens TolC ortholog, was expressed in KAM43, all of the genes conferred resistance on E. coli, suggesting that HasF is a major outer membrane protein that is used by all RND efflux systems in this organism. We constructed a sdeXY deletion mutant from a derivative strain of the clinically isolated multidrug-resistant S. marcescens strain and found that the sdeXY deletion mutant was sensitive to a broad spectrum of antimicrobial agents.

MALDI-TOF mass spectrometry (MS) may be used as a rapid typing method for nosocomial pathogens. Here, we evaluated MALDI-TOF MS for discrimination of hospital outbreak-related clusters of Serratia marcescens and carbapenemase-producing Citrobacter freundii. Thirty-three S. marcescens isolates collected from neonatal intensive care unit (NICU) patients, and 23 C. freundii isolates including VIM-positive isolates from a hospital colonization outbreak were measured by Vitek MS. Consensus spectra of each isolate were clustered using SARAMIS software. Genotyping was performed by whole-genome sequencing (WGS). First, a set of 21 S. marcescens isolates from 2014 with seven genotypes including three monoclonal clusters was used for the evaluation of MALDI-TOF typing. MS clustering was largely in agreement with genotyping results when the similarity cut-off for clonal identity was set on 90%. MALDI-TOF cluster analysis was then investigated for the surveillance of S. marcescens in the NICU in 2017 and demonstrated the introduction of new strains into the hospital and nosocomial transmissions. MS analysis of the C. freundii outbreak in 2016 revealed a monoclonal cluster of VIM-positive isolates and the separation of epidemiologically non-related VIM-positive and negative isolates. Two additional VIM-positive Citrobacter isolates from food samples were closely related to the large monoclonal cluster. WGS confirmed the MS results. MALDI-TOF MS may be used as a first-line typing tool for S. marcescens and C. freundii to detect transmission events in the hospital because isolates of an identical WGS type were grouped into the same MS cluster.

Serratia marcescens NJ01 is a pathogenic bacterium isolated from diseased tomato leaves. Here, we report on the development of a tomato- S. marcescens host-pathogen system as a model to evaluate the effects of hordenine on quorum sensing (QS)-mediated pathogenicity under native conditions. Exposure to hordenine at 25, 50, and 100 μg/mL significantly inhibited the production of acyl-homoserine lactones and the formation of biofilms. Hordenine treatment notably enhanced the susceptibility of the preformed biofilms to ciprofloxacin by reducing the production of extracellular polysaccharides, destroying the architecture of biofilms, and changing the permeability of membranes, as evidenced by the scattered appearance and dominant red fluorescence in the combination-treated biofilms. Furthermore, the addition of hordenine affected the production of virulence factors, influenced the intracellular metabolites, and downregulated the expressions of QS- and biofilm-related genes. The plant infection model indicated that hordenine could significantly attenuate the pathogenicity of S. marcescens NJ01 in tomato plants. Thus, hordenine could act as a potential pesticide or pesticide accelerant in treating crop infections.

Mosquitoes are hematophagous vectors that can acquire human viruses in their intestinal tract. Here, we define a mosquito gut commensal bacterium that promotes permissiveness to arboviruses. Antibiotic depletion of gut bacteria impaired arboviral infection of a lab-adapted Aedes aegypti mosquito strain. Reconstitution of individual cultivable gut bacteria in antibiotic-treated mosquitoes identified Serratia marcescens as a commensal bacterium critical for efficient arboviral acquisition. S. marcescens facilitates arboviral infection through a secreted protein named SmEnhancin, which digests membrane-bound mucins on the mosquito gut epithelia, thereby enhancing viral dissemination. Field Aedes mosquitoes positive for S. marcescens were more permissive to dengue virus infection than those free of S. marcescens. Oral introduction of S. marcescens into field mosquitoes that lack this bacterium rendered these mosquitoes highly susceptible to arboviruses. This study defines a commensal-driven mechanism that contributes to vector competence, and extends our understanding of multipartite interactions among hosts, the gut microbiome, and viruses., (Copyright © 2018 Elsevier Inc. All rights reserved.)

In the current study, the anti-quorum sensing (QS) efficacy of cyclic dipeptide -cyclo(L-leucyl-L-prolyl) (CLP) of marine origin was explored against Serratia marcescens. Minimal -inhibitory (MIC) and -bactericidal concentrations (MBC) of CLP against both reference as well as a clinical isolate of S. marcescens was identified to be 200 and 400 µg/mL, respectively. CLP proficiently inhibited the QS controlled prodigiosin production in S. marcescens, which affirm its anti-QS efficacy towards S. marcescens. At sub-MIC (100 µg/mL), CLP exhibited a phenomenal inhibitory propensity towards the production of virulence traits viz. biofilm, exopolymeric substance, protease and lipase to the level of 81, 77, 71 and 92%, respectively. Further, the confocal and scanning electron microscopic analyses validated the antibiofilm efficacy of CLP. Besides, CLP effectively modified the hydrophobic and motility characteristics of S. marcescens. Furthermore, the in vivo assay using C. elegans revealed the non-toxic and anti-adherence propensity of CLP. Concomitantly, the down regulation of QS controlled virulence genes (unveiled through qPCR analysis) are in accordance with the data of phenotypic and in vivo assays. Therefore, this study exemplifies that CLP could plausibly be a convincing alternative over conventional antibiotics in preventing the QS associated pathogenesis of uropathogens., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Purpose: To compare effects of 5% topical povidone iodine with prophylactic topical azithromycin and moxifloxacin on bacterial flora in patients undergoing intravitreal injection., Methods: A total of 132 patients were randomly assigned to receive treatment with azithromycin or moxifloxacin, or no treatment (control group). In total, 528 specimens were obtained at the time of admission, 4 days before intravitreal injection, 4 days after intravitreal injection, and 8 days after intravitreal injection. Samples were immediately sent to the microbiology laboratory for incubation., Results: The microorganism observed most frequently was coagulasenegative Staphylococcus (23.8%). When the results of samples obtained on Day 4 before injection were assessed, growth of coagulase-negative Staphylococcus was significantly lower in the moxifloxacin group, compared with controls (p=0.049). Acinetobacter baumannii continued to grow after administration of azithromycin (p=0.033). When the results of four days after intravitreal injection were evaluated, growth of coagulase-ne gative Staphylococcus was higher in controls, compared with patients who received azithromycin or moxifloxacin (p=0.004). Eradication rate was significantly higher in the moxifloxacin group than in the control group (p=0.001). Samples obtained on Day 8 after intravitreal injection showed similar levels of bacterial growth in all groups (p=0.217)., Conclusion: Moxifloxacin was more effective than 5% povidone iodine in controlling the growth of conjunctival bacterial flora. Use of moxifloxacin in combination with 5% povidone iodine resulted in a synergistic effect.

Microbial keratitis is the infection caused by pathogenic microorganisms that commonly occurs among the contact lens users. Various antimicrobial compounds were coated on contact lenses to kill keratitis causing microorganisms, however these compounds caused several adverse side effects. Hence, the aim of this study is to develop a silicone hydrogel contact lens coated with phomopsidione nanoparticle that inhibit keratitis causing clinical isolates. Phomopsidione nanoparticles were synthesized using polyvinyl alcohol as encapsulant. The nanoparticles showed an average size of 77.45 nm, with neutral surface charge. Two drug release patterns were observed in the drug release profile, which are the initial slow release phase with extended drug release (release rate 46.65 μg/h), and the burst release phase observed on Day 2 (release rate 2224.49 μg/h). This well-regulated drug delivery system enables the control of drug release to meet the therapeutic requirements. On agar diffusion assay, 3 out of 5 test microorganisms were inhibited by phomopsidione nanoparticle coated contact lenses, including two Gram negative bacteria. Besides, all test microorganisms showed at least 99% of growth reduction, with the treatment of the contact lens model. The drug loaded onto the nanoparticles is sufficient to prevent the bacterial growth. In conclusion, this study provides an effective alternative to combat keratitis-causing microorganisms among contact wearers., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We observed the death of insect caterpillars of Spodoptera exigua in the laboratory culture line and identified Serratia marcescens as the bacterial causative agent of the insect death. We confirmed that S. marcescens had insecticidal activity against S. exigua and caused high mortality of larvae. The LC 50 values of S. marcescens CFU per 1 cm 2 of insect diet surface were similar for all isolates. Our research reports novel strains with high pesticidal activity as candidates for future research on a new bioinsecticide. As bioinsecticides cannot be harmful to non-target organisms, we determined the pathogenic properties of S. marcescens to humans. We proved the ability of S. marcescens to damage mammalian epithelial cells. All strains had cytopathic effects to Vero cells with a cytotoxic index ranging from 51.2% ± 3.8% to 79.2% ± 4.1%. We found that all of the strains excreted catecholate siderophore - enterobactin. All isolates were resistant to sulfamethoxazole, tobramycin, gentamicin, cefepime, and aztreonam. We did not observe the ESBL phenotype and the integrons' integrase genes. Resistance to sulfamethoxazole was due to the presence of the sul1 or sul2 gene. The use of resistant S. marcescens strains that are pathogenic to humans in plant protection may cause infections difficult to cure and lead to the spread of resistance genes. The results of our study emphasize the necessity of determination of the safety to vertebrates of the bacteria that are proposed to serve as biocontrol agents. The novelty of our study lies in the demonstration of the indispensability of the bacteria verification towards the lack of hazardous properties to humans., We observed the death of insect caterpillars of Spodoptera exigua in the laboratory culture line and identified Serratia marcescens as the bacterial causative agent of the insect death. We confirmed that S. marcescens had insecticidal activity against S. exigua and caused high mortality of larvae. The LC 50 values of S. marcescens CFU per 1 cm 2 of insect diet surface were similar for all isolates. Our research reports novel strains with high pesticidal activity as candidates for future research on a new bioinsecticide. As bioinsecticides cannot be harmful to non-target organisms, we determined the pathogenic properties of S. marcescens to humans. We proved the ability of S. marcescens to damage mammalian epithelial cells. All strains had cytopathic effects to Vero cells with a cytotoxic index ranging from 51.2% ± 3.8% to 79.2% ± 4.1%. We found that all of the strains excreted catecholate siderophore – enterobactin. All isolates were resistant to sulfamethoxazole, tobramycin, gentamicin, cefepime, and aztreonam. We did not observe the ESBL phenotype and the integrons’ integrase genes. Resistance to sulfamethoxazole was due to the presence of the sul1 or sul2 gene. The use of resistant S. marcescens strains that are pathogenic to humans in plant protection may cause infections difficult to cure and lead to the spread of resistance genes. The results of our study emphasize the necessity of determination of the safety to vertebrates of the bacteria that are proposed to serve as biocontrol agents. The novelty of our study lies in the demonstration of the indispensability of the bacteria verification towards the lack of hazardous properties to humans.

Aim: Serratia marcescens clinical isolates are increasingly resistant to antibiotics. Therefore, the treatment of infections caused by S. marcescens becomes difficult. The aim of this study was to examine the antimicrobial resistance profiles of S. marcescens bacteria isolated from various clinical specimens according to body regions and clinics and to evaluate for enzyme production rates associated with antibiotic resistance of these isolates., Materials and Methods: Blood culture samples were incubated in a fully automated BACTEC-FX system. Identification and antibiogram processing was carried out by fully automated VITEK 2 identification and antibiogram system. The obtained results were retrospectively screened., Results: S. marcescens was identified in a total of 158 clinical specimens. The departments where S. marcescens was most commonly identified were the Anesthesia Intensive Care Unit (25.9%), followed by Chest Diseases (19.6%). Serratia isolates were most commonly determined in blood culture (35.4%) and sputum culture (24.6%). Resistance rates to ceftriaxone and ceftazidime were 22.7% and 19.6%, respectively. However, the rate of resistance detected to cefotaxime and gentamicin (0.6%) was very low., Conclusion: Clinical isolates of Serratia exhibited highest resistance to ceftriaxone, ceftazidime, and piperacillin/tazobactam. However, it was found that the tested Serratia strains did not exhibit high resistance to other antibiotics. Our results suggest that cefotaxime and gentamicin are the most suitable antibiotics for treatment. The extended-spectrum β-lactamase and inducible β-lactamase ratios were found to be decreased by 6%-7%. Although different results may be obtained from different hospitals and regions, it should not be forgotten that Serratia strains may be resistant to many antibiotics and that the results of antibiotic susceptibility testing may help plan antibiotic treatment., Competing Interests: There are no conflicts of interest.

Ornithine decarboxylase (ODC) is an immediate precursor of polyamine biosynthesis in Serratia marcescens and a potential target for inhibition of its growth. We predicted the 3D structural conformation of ODC enzyme and validated it using MDS in our previous study. In this current study, the potential inhibitors of ODC were obtained by virtual screening of potential inhibitors from ZINC database and studied in depth for their different binding pose. Among the ten virtually screened inhibitors, Conessine exhibited the best binding with ODC and its inhibition property was studied further by MDS studies. The natural compound conessine is isolated from plant Holarrhena antidysenterica and it is studied against ODC of Serratia marcenses for its inhibitory potentials. This revealed unforeseen twisted position in root mean square fluctuation (RMSF) and ODC modelled conformation that influenced ligand binding. Both predicted model and ligand bound model were compared and found to be stable with Root Mean Square Deviation (RMSD) of approximately 7 nm and 0.25 nm to that of crystallographic structure over simulation time of 55 ns and 70 ns respectively. This work paves the way for future development of new drugs against nosocomial diseases caused by Serratia marcescens., (Copyright © 2018. Published by Elsevier B.V.)

This work illustrates a new role for the membranotropic peptide gH625 and its derivative gH625-GCGKKK in impairing formation of polymicrobial biofilms. Mixed biofilms composed of Candida and bacterial species cause frequently infections and failure of medical silicone devices and also show a major drug resistance than single-species biofilms. Inhibition and eradication of biofilms were evaluated by complementary methods: XTT-reduction, and crystal violet staining (CV). Our results indicate that gH625-GCGKKKK, better than the native peptide, strongly inhibited formation of mixed biofilms of clinical isolates of C. tropicalis/S. marcescens and C. tropicalis/S. aureus and reduced the biofilm architecture, interfering with cell adhesion and polymeric matrix, as well as eradicated the long-term polymicrobial biofilms on silicone surface., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

We evaluated the genetic environment of bla GES-16 found in 2 carbapenem-resistant Serratia marcescens clinical isolates recovered from patients hospitalized at a tertiary hospital located in Rio de Janeiro, Brazil. We also compared the kinetics constants for GES-16 and GES-5 against several β-lactams. Both S. marcescens isolates showed identical PFGE pattern and carried the carbapenemase-encoding gene bla GES-16 and the extended-spectrum β-lactamase encoding gene bla OXA-10 . The bla GES-16 was inserted at the first position of a defective class 1 integron, composed by a fragmented integrase gene that lacked its attI1 recombination site, followed by dfr22, aac(6')-IIc, and aadA1 genes. This integron was located on a 30-kb nonconjugative plasmid. The GES-16 showed 2 amino acid substitutions (Gln38Glu and Gly170Ser) compared to GES-1. Kinetic analysis showed that GES-16 presented hydrolytic activity against all β-lactams tested, except for aztreonam. Imipenem was the carbapenem more efficiently hydrolyzed (highest k cat /K m ) by GES-16. The kinetic parameters of GES-16 were similar to those of GES-5. In conclusion, we identified a new GES-type enzyme with carbapenemase activity in S. marcescens. The increasing diversity of such resistance determinants confirms the ongoing evolution of these β-lactamases towards a broader spectrum of activity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Persisters represent a small bacterial population that is dormant and that survives under antibiotic treatment without experiencing genetic adaptation. Persisters are also considered one of the major reasons for recalcitrant chronic bacterial infections. Although several mechanisms of persister formation have been proposed, it is not clear how cells enter the dormant state in the presence of antibiotics or how persister cell formation can be effectively controlled. A fatty acid compound, cis-2-decenoic acid, was reported to decrease persister formation as well as revert the dormant cells to a metabolically active state. We reasoned that some fatty acid compounds may be effective in controlling bacterial persistence because they are known to benefit host immune systems. This study investigated persister cell formation by pathogens that were exposed to nine fatty acid compounds during antibiotic treatment. We found that three medium chain unsaturated fatty acid ethyl esters (ethyl trans-2-decenoate, ethyl trans-2-octenoate, and ethyl cis-4-decenoate) decreased the level of Escherichia coli persister formation up to 110-fold when cells were exposed to ciprofloxacin or ampicillin antibiotics. RNA sequencing analysis and gene deletion persister studies elucidated that these fatty acids inhibit bacterial persistence by regulating antitoxin HipB. A similar persister cell reduction was observed for pathogenic E. coli EDL933, Pseudomonas aeruginosa PAO1, and Serratia marcescens ICU2-4 strains. This study demonstrates that fatty acid ethyl esters can be used to disrupt bacterial dormancy to combat persistent infectious diseases.

We report contemporary (2014-2016) Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) global data on activity of tigecycline and comparators against WHO 'priority pathogens', and global trends (2004-2016) in antimicrobial resistance. MICs were determined using CLSI broth microdilution methodology. Antimicrobial resistance was determined using CLSI breakpoints (FDA breakpoints for tigecycline). Data are reported for Africa, Asia, Europe, North America and South America. From 2014-2016, Africa, Asia and South America reported highest resistance rates among Acinetobacter baumannii; North America lowest (all antimicrobials tested). The tigecycline MIC 90 against A. baumannii was 2 mg/L in all regions except South America (1 mg/L). Among Enterobacteriaceae, meropenem resistance was low and tigecycline resistance was ≤1.3% in all regions (Escherichia coli, 0.0-0.3%; Klebsiella pneumoniae 0.0-1.3%; Enterobacter spp. 0.5-1.1%; Serratia marcescens 0.0-1.3%). Ceftriaxone resistance among E. coli ranged from 14.5% (North America) to 54.7% (Asia), and among K. pneumoniae from 9.1% (North America) to 54.0% (South America). North America reported highest rates of vancomycin-resistant Enterococcus faecium (64.6%); Europe lowest (17.7%). The tigecycline MIC 90 against methicillin-resistant Staphylococcus aureus (MRSA) ranged from 0.12 mg/L (Africa and North America) to 0.5 mg/L (Asia). From 2004-2016, carbapenem resistance increased among A. baumannii (all regions), reaching 92.3% in Africa and 85.7% in South America (2016). Rates of ceftriaxone-resistant E. coli increased in all regions except Asia. Ceftriaxone resistance in K. pneumoniae increased in Europe. Rates of vancomycin-resistant E. faecium and MRSA were highest in North America and South America (and Asia for MRSA); lowest in Europe., (Copyright © 2018. Published by Elsevier B.V.)

Serratia marcescens is an opportunistic human pathogen causing various nosocomial infections, most importantly urinary tract infections (UTIs). It exhibits increased resistance towards the conventional antibiotics. This study was aimed to evaluate the anti-virulence effect of a rhizosphere soil bacterium Bacillus subtilis strain R-18 against the uropathogen S. marcescens. First, the bacterial cell-free culture supernatant (CFCS) of B. subtilis strain R-18 was evaluated for its quorum sensing inhibitory (QSI) potential against biomarker strain Chromobacterium violaceum and the test pathogen S. marcescens. The B. subtilis R-18 CFCS effectively inhibited the quorum sensing (QS)-mediated violacein pigment production in C. violaceum and prodigiosin pigment production in S. marcescens. Furthermore, B. subtilis R-18 CFCS was successively extracted with different solvent systems. Of these solvents, B. subtilis R-18 petroleum ether (PE) extract showed inhibition in biofilm formation, protease, lipase, and hemolysin productions in S. marcescens. Fourier transform infrared spectroscopic (FT-IR) analysis revealed the alterations in the cellular components of bacterial cell pellets obtained from B. subtilis R-18 PE extract treated and untreated S. marcescens. The differential gene expression study further validated the downregulation of virulence-associated genes. Characterization of the active principle in B. subtilis R-18 PE extract by gas chromatography-mass spectrometry (GC-MS) analysis showed the presence of multiple compounds with therapeutic values, which could possibly reduce the QS-dependent phenotypes in S. marcescens., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Aim: Serratia marcescens is an important multidrug-resistant human pathogen. The pathogenicity of S. marcescens mainly depends on the quorum sensing (QS) mechanism, which regulates the virulence factors production and biofilm formation. Hence, targeting QS mechanism in S. marcescens will ultimately pave the way to combat its pathogenicity. Thus, the present study is intended to evaluate the efficacy of Vetiveria zizanioides root extract-mediated silver nanoparticles (AgNPs) as a potent anti-QS and antibiofilm agent against S. marcescens., Methods and Results: The AgNPs were synthesized using V. zizanioides aqueous root extract and the physiochemical properties of V. zizanioides-based AgNPs (VzAgNPs) were evaluated using analytical techniques such as ultraviolet-visible absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, dynamic light scattering and scanning and transmission electron microscopic techniques. VzAgNPs were found to attenuate the QS-dependent virulence factors, namely prodigiosin, protease, lipase, exopolysaccharide productions and biofilm formation of S. marcescens, without inhibiting its growth. Further, the transcriptomic analysis confirmed the down-regulation of QS-dependent genes, which encode for the production of virulence factors and biofilm formation., Conclusion: The current study confirms VzAgNPs as an ideal anti-QS and antibiofilm agent against S. marcescens., Significance and Impact of the Study: This is the first approach that validates the anti-QS and antibiofilm potential of phytosynthesized VzAgNPs against the nosocomial pathogen, S. marcescens. As VzAgNPs exhibits potent antivirulent activities, it could be used to treat hospital-acquired S. marcescens infections., (© 2018 The Society for Applied Microbiology.)

Objectives: Antibiotic selective pressure may result in changes to antimicrobial susceptibility throughout the course of infection, especially for organisms that harbour chromosomally encoded AmpC β-lactamases, notably Enterobacter spp., in which hyperexpression of ampC may be induced following treatment with cephalosporins. In this study, we document a case of bacteraemia caused by a blaSME-1-harbouring Serratia marcescens that subsequently developed resistance to expanded-spectrum cephalosporins, piperacillin/tazobactam and fluoroquinolones, over the course of several months of treatment with piperacillin/tazobactam and ciprofloxacin., Methods: Susceptibility testing and WGS were performed on three S. marcescens isolates from the patient. β-Lactamase activity in the presence or absence of induction by imipenem was measured by nitrocefin hydrolysis assays. Expression of ampC and blaSME-1 under the same conditions was determined by real-time PCR., Results: WGS demonstrated accumulation of missense and nonsense mutations in ampD associated with stable derepression of AmpC. Gene expression and β-lactamase activity of both AmpC and SME-1 were inducible in the initial susceptible isolate, but were constitutively high in the resistant isolate, in which total β-lactamase activity was increased by 128-fold., Conclusions: Although development of such in vitro resistance due to selective pressure imposed by antibiotics is reportedly low in S. marcescens, our findings highlight the need to evaluate isolates on a regular basis during long-term antibiotic therapy.

Whole-genome sequence analyses revealed the presence of bla NDM-1 ( n = 31), bla GES-5 ( n = 8), bla OXA-232 ( n = 1), or bla NDM-5 ( n = 1) in extensively drug-resistant and pandrug-resistant Enterobacteriaceae organisms isolated from in-patients in 10 private hospitals (2012 to 2013) in Durban, South Africa. Two novel NDM-1-encoding plasmids from Klebsiella pneumoniae were circularized by PacBio sequencing. In p19-10&#95;01 [IncFIB(K); 223.434 bp], bla NDM-1 was part of a Tn 1548 -like structure (16.276 bp) delineated by IS 26 The multireplicon plasmid p18-43&#95;01 [IncR&#95;1/IncFIB(pB171)/IncFII(Yp); 212.326 bp] shared an 80-kb region with p19-10&#95;01, not including the bla NDM-1 -containing region. The two plasmids were used as references for tracing NDM-1-encoding plasmids in the other genome assemblies. The p19-10&#95;01 sequence was detected in K. pneumoniae ( n = 7) only, whereas p18-43&#95;01 was tracked to K. pneumoniae ( n = 4), Klebsiella michiganensis ( n = 1), Serratia marcescens ( n = 11), Enterobacter spp. ( n = 7), and Citrobacter freundii ( n = 1), revealing horizontal spread of this bla NDM-1 -bearing plasmid structure. Global phylogeny showed clustering of the K. pneumoniae (18/20) isolates together with closely related carbapenemase-negative ST101 isolates from other geographical origins. The South African isolates were divided into three phylogenetic subbranches, where each group had distinct resistance and replicon profiles, carrying either p19-10&#95;01, p18-10&#95;01, or pCHE-A1 (8,201 bp). The latter plasmid carried bla GES-5 and aacA4 within an integron mobilization unit. Our findings imply independent plasmid acquisition followed by local dissemination. Additionally, we detected bla OXA-232 carried by pPKPN4 in K. pneumoniae (ST14) and bla NDM-5 contained by a pNDM-MGR194-like genetic structure in Escherichia coli (ST167), adding even more complexity to the multilayer molecular mechanisms behind nosocomial spread of carbapenem-resistant Enterobacteriaceae in Durban, South Africa., (Copyright © 2018 American Society for Microbiology.)

The aim of this study was to evaluate the anti-biofilm and anti-virulence properties of petroselinic acid (PSA) against the environmental pathogen Serratia marcescens. PSA significantly inhibited the quorum sensing (QS)-dependent virulence factors such as prodigiosin, protease productions, and biofilm formation in S. marcescens. The antibiofilm potential of PSA was also confirmed through light, confocal laser scanning, and scanning electron microscopic analyses. Furthermore, PSA effectively inhibited the biofilm-related phenomena such as exopolysaccharide production, hydrophobicity production, swimming, and swarming motility without affecting the bacterial growth. In FT-IR analysis, the PSA treated S. marcescens cells displayed a reduction in cellular components compared to the untreated controls. The real-time analysis revealed the downregulation of QS-controlled virulence genes such as bsmB, fimA, fimC, and flhD in S. marcescens on treatment with PSA. The obtained results strongly suggested that PSA could be further explored as an antipathogenic drug to treat QS-mediated infections caused by S. marcescens.

Urinary tract infections are the utmost common bacterial infections caused by Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, and Serratia marcescens. These uropathogens resist the action of several antibiotics due to their ability to form biofilms. Most of these bacterial pathogens use the quorum sensing (QS) machinery to co-ordinate their cells and regulate several virulence factors and biofilm formation. On the other hand, the anti-quorum sensing (anti-QS) and antibiofilm potential of silver nanoparticles have been well reported against certain bacterial pathogens, but to the best of our knowledge, no report is available against the pathogenicity of uropathogens in particular S. marcescens and P. mirabilis. Therefore, the present study is primarily focused on the anti-QS and antibiofilm potential of Piper betle-based synthesized silver nanoparticles (PbAgNPs) against S. marcescens and P. mirabilis. Initially, the silver nanoparticles were synthesized by the aqueous extract of P. betle and characterized by UV-absorbance spectroscopy, XRD, FT-IR, SEM, TEM, and DLS. The synthesized silver nanoparticles were assessed for their anti-QS activity and the obtained results revealed that the PbAgNPs inhibited the QS-mediated virulence factors such as prodigiosin, protease, biofilm formation, exopolysaccharides and hydrophobicity productions in uropathogens. The gene expression analysis divulged the downregulation of fimA, fimC, flhD, and bsmB genes in S. marcescens and flhB, flhD, and rsbA genes in P. mirabilis, respectively. The in vivo Caenorhabditis elegans assays revealed the non-toxic and anti-adherence efficiency of PbAgNPs. Furthermore, the non-toxic effect of PbAgNPs was also confirmed through peripheral blood mononuclear cells and normal lung epithelial cells. Therefore, the contemporary study demonstrates the use of PbAgNPs as a possible alternative toward conventional antibiotics in controlling QS and biofilm-related uropathogen infections.

Background: Quorum sensing is a cell-to-cell communication system in bacteria that controls the production of virulence factors. Serratia marcescens is a causative agent of hospital-acquired infections that shows high resistance to antibiotics. This makes the treatment of these infections difficult. Quorum sensing regulates the production of virulence factors of S. marcescens such as prodigiosin, protease, swimming and swarming motilities and formation of biofilms. Inhibition of quorum sensing may be an alternative to antibiotic treatment to avoid emergence of resistance., Objectives: Testing the ability of glyceryl trinitrate to inhibit quorum sensing and virulence factors of Serratia marcescens ., Methods: The inhibiting activities of sub-inhibitory concentration of glyceryl trinitrate against the quorum-sensing regulated violacein pigment in Chromobacterium violaceum CV026 was performed to evaluate the anti-quorum sensing effect of glyceryl trinitrate. The anti-virulence activity was assessed against prodigiosin, protease, biofilm formation in addition to swimming and swarming motilities., Results: Glyceryl trinitrate at at a concentration of 0.25 mg/ml produced significant inhibitory effects against violacein (67.01%), prodigiosin (82.67%), protease, swimming (36.72%) and swarming (79.31%) motilities and biofilm formation (87.83%)., Conclusion: Glyceryl trinitrate is a quorum sensing and virulence inhibitor that may be useful in treatment of nosocomial infections caused by Serratia marcescens .

Purpose: There is currently a paucity of published literature focused on the treatment of infections caused by NDM-producing organisms., Methods: We describe a case of a bacteraemia caused by an extensively drug-resistant (XDR) New Delhi metallo-β-lactamase (NDM)-producing Serratia marcescens and review the treatment options for XDR NDM-producing Enterobacteriaceae., Results: Infections caused by New Delhi beta-lactamase (NDM)-producing Enterobacteriaceae are becoming increasingly prevalent worldwide. The presence of the enzyme results in multidrug-resistant and extensively drug-resistant phenotypes which often pose a treatment challenge. Despite this challenge, case reports and series have demonstrated good clinical outcomes with numerous treatment options in comparison to infections due to KPC-producing Enterobacteriaceae., Conclusions: Further good-quality research focused on the treatment of NDM-producing Enterobacteriaceae is warranted.

Purpose: We have previously shown that invasive strains of Pseudomonas aeruginosa exploit the robust neutrophil response to form biofilms on contact lens surfaces and invade the corneal epithelium. The present study investigated the ability of multiple bacterial genera, all commonly recovered during contact lens-related infectious events, to adhere to and form biofilms on contact lens surfaces in the presence of neutrophils., Methods: Five reference strains from the American Type Culture Collection were used: P. aeruginosa, Serratia marcescens, Stenotrophomonas maltophilia, Staphylococcus aureus, and Staphylococcus epidermidis . Each bacterial strain was incubated overnight with or without stimulated human neutrophils in the presence of an unworn contact lens. Standard colony counts and laser scanning confocal microscopy of BacLight-stained contact lenses were used to assess bacterial viability. Three-dimensional modeling of lens-associated biofilms with Imaris software was used to determine the biofilm volume. Lenses were further examined using scanning electron microscopy., Results: Less than 1% of the starting inoculum adhered to the contact lens surface incubated with bacteria alone. There were no differences in adhesion rates to contact lens surfaces between bacteria in the absence of neutrophils for either the Gram-negative or Gram-positive test strains. Bacterial adhesion to contact lens surfaces was accelerated in the presence of human neutrophils for all test strains. This effect was least evident with S. epidermidis. There was also an increase in the number of viable bacteria recovered from contact lens surfaces (p<0.001 for the Gram-negative and Gram-positive test strains, respectively) and in biofilm volume (p<0.001 for the Gram-negative test strains, p = 0.005 for S. aureus )., Conclusions: These results show that in addition to P. aeruginosa , other bacteria commonly encountered during contact lens wear possess the capacity to utilize neutrophil-derived cellular debris to facilitate colonization of the lens surface. These data suggest that this phenomenon is conserved among multiple genera. Thus, during contact lens wear, the presence of inflammation and the accumulation of neutrophil debris under the posterior lens surface likely contribute to colonization of the lens. Further studies are needed to correlate these findings with risk for infection in an animal model.

Uterine artery embolization (UAE)-assisted induction of labor is an alternative method of managing pregnant women with complete placenta previa (CPP). Sepsis secondary to UAE, although rare, is a serious complication. We herein present a case of severe sepsis following UAE-assisted termination of a pregnancy at 27 gestational weeks in a woman with CPP. The woman developed a high-grade fever and elevated inflammatory indices following UAE. She did not recover until the infected tissue was removed by emergency cesarean section. This case suggests that the increasing use of UAE for termination of pregnancy in women with CPP requires awareness regarding the possibility of serious sepsis associated with this procedure.

Quorum Sensing (QS) mechanism, a bacterial density-dependent gene expression system, governs the Serratia marcescens pathogenesis through the production of virulence factors and biofilm formation. The present study demonstrates the anti-quorum sensing (anti-QS), antibiofilm potential and in vivo protective effect of phytol, a diterpene alcohol broadly utilized as food additive and in therapeutics fields. In vitro treatment of phytol (5 and 10 μg/ml) showed decreasing level of biofilm formation, lipase and hemolysin production in S. marcescens compared to their respective controls. More, microscopic analyses confirmed the antibiofilm potential of phytol. The biofilm related phenomenons such as swarming motility and exopolysccharide productions were also inhibited by phytol. Furthermore, the real-time analysis elucidated the molecular mechanism of phytol which showed downregulation of fimA, fimC, flhC, flhD, bsmB, pigP , and shlA gene expressions. On the other hand, the in vivo rescue effect of phytol was assessed against S. marcescens associated acute pyelonephritis in Wistar rat. Compared to the infected and vehicle controls, the phytol treated groups (100 and 200 mg/kg) showed decreased level of bacterial counts in kidney, bladder tissues and urine samples on the 5th post infection day. As well, the phytol treatment showed reduced level of virulence enzymes such as lipase and protease productions compared to the infected and vehicle controls. Further, the infected and vehicle controls showed increasing level of inflammatory markers such as malondialdehyde (MDA), nitric oxide (NO) and myeloperoxidase (MPO) productions. In contrast, the phytol treatment showed decreasing level of inflammatory markers. In histopathology, the uninfected animal showed normal kidney and bladder structure, wherein, the infected animals showed extensive infiltration of neutrophils in kidney and bladder tissues. In contrast, the phytol treatment showed normal kidney and bladder tissues. Additionally, the toxic effect of phytol (200 mg/kg) was assessed by single dose toxicity analysis. No changes were observed in hematological, biochemical profiles and histopathological analysis of vital organs in phytol treated animals compared to the untreated controls. Hence, this study suggested the potential use of phytol for its anti-QS, antibiofilm and anti-inflammatory properties against S. marcescens infections and their associated inflammation reactions.

A bioactive ligand and its dinuclear metal(II) complexes were synthesized and characterized by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Visible), nuclear magnetic resonance (¹H-NMR), mass spectroscopy and molar conductance measurements. The ligand has been crystalized in the monoclinic system with a P21/c space group. The biological activities of metal complexes were evaluated using disc diffusion and broth dilution methods. In vitro antibacterial activities of the ligand and their metal complexes were examined against two Gram-positive bacteria ( Bacillus subtilis and Staphylococcus aureus ) and two Gram-negative bacteria ( Escherichia coli and Serratia marcescens ) and compared to the standard drugs. It was found that metal complexes displayed much higher antibacterial activities and better inhibitory effects than that of the ligand and standard drugs. Among these complexes, the compound having Zn-metal showed greater antibacterial activity against all four tested bacteria and was more effective against Serratia marcescens with the zone inhibition diameter of 26 mm and MIC value of 31.25 µg/mL., Competing Interests: The authors declare no conflict of interest.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been associated with serious urinary tract infections (UTIs) including pyelonephritis and urosepsis. The Food and Drug Administration (FDA) issued a label change to include this warning in December 2015 due to a small number of cases (n = 19) reported to the FDA Adverse Event Reporting System. Details of these cases are limited and none involved empagliflozin. To date, there has been no published literature comprehensively describing serious UTIs attributed to empagliflozin. We describe a case of septic shock due to Serratia marcescens pyelonephritis and bacteremia that required intensive care unit admission in a well-controlled, type 2 diabetic patient who had begun taking empagliflozin 2 months prior. The patient was treated successfully with intravenous antibiotics followed by oral ciprofloxacin. After discontinuation of empagliflozin and completion of antibiotic therapy, no subsequent UTIs were documented in the following 4 months.

To grapple with multidrug resistant bacterial infections, implementations of antibacterial nanomedicines have gained prime attention of the researchers across the globe. Nowadays, zinc oxide (ZnO) at nano-scale has emerged as a promising antibacterial therapeutic agent. Keeping this in view, ZnO nanostructures (ZnO-NS) have been synthesised through reduction by P. aphylla aqueous extract without the utilisation of any acid or base. Structural examinations via scanning electron microscopy (SEM) and X-ray diffraction have revealed pure phase morphology with highly homogenised average particle size of 18 nm. SEM findings were further supplemented by transmission electron microscopy examinations. The characteristic Zn-O peak has been observed around 363 nm using ultra-violet-visible spectroscopy. Fourier-transform infrared spectroscopy examination has also confirmed the formation of ZnO-NS through detection of Zn-O bond vibration frequencies. To check the superior antibacterial activity of ZnO-NS, the authors' team has performed disc diffusion assay and colony forming unit testing against multidrug resistant E. coli, S. marcescens and E. cloacae . Furthermore, protein kinase inhibition assay and cytotoxicity examinations have revealed that green fabricated ZnO-NS are non-hazardous, economical, environmental friendly and possess tremendous potential to treat lethal infections caused by multidrug resistant pathogens.

Objectives: Bloodstream infections (BSIs) are a major cause of paediatric morbidity and mortality worldwide. This study describes the epidemiology and antimicrobial resistance of Gram-negative bacteria (GNB) from BSIs in children admitted to an Iranian paediatric hospital., Methods: Clinical and microbiological data of patients with positive blood cultures were collected from March 2011 to September 2016. Standard laboratory methods were used for blood culture and bacterial identification. Antimicrobial sensitivity was evaluated by the Kirby-Bauer disk diffusion and broth microdilution methods., Results: Of 2325 bacterial pathogens isolated from blood cultures, 41.1% (n=956) were GNB. Most clinical isolates (n=208; 21.8%) were identified in the cardiac intensive care unit. Predominant bacterial isolates were Klebsiella pneumoniae subsp. pneumoniae (n=263; 27.5%), Escherichia coli (n=192; 20.1%), Serratia marcescens (n=151; 15.8%), Pseudomonas aeruginosa (n=111; 11.6%) and Enterobacter spp. (n=100; 10.5%). Enterobacter isolates showed a high level of ampicillin resistance. Escherichia coli were highly resistant to chloramphenicol (100%), cefixime (100%), ceftriaxone (100%) and ampicillin (96%). Cefixime had the least efficacy against Haemophilus spp. (100% resistant). All K. pneumoniae (100%) were ampicillin-resistant. All S. marcescens were ceftazidime-resistant. No Acinetobacter baumannii were resistant to colistin. All P. aeruginosa were resistant to cefotaxime and trimethoprim/sulfamethoxazole., Conclusions: These results demonstrate the increasing trend in antibiotic resistance among GNB associated with BSI in children, emphasising the importance of continuous screening and surveillance programmes for detection of antibiotic resistance in BSI pathogens for selection of appropriate treatment regimens., (Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

Serratia marcescens is one of the important nosocomial pathogens which rely on quorum sensing (QS) to regulate the production of biofilm and several virulence factors. Hence, blocking of QS has become a promising approach to quench the virulence of S. marcescens. For the first time, QS inhibitory (QSI) and antibiofilm potential of Actinidia deliciosa have been explored against S. marcescens clinical isolate (CI). A. deliciosa pulp extract significantly inhibited the virulence and biofilm production without any deleterious effect on the growth. Vanillic acid was identified as an active lead responsible for the QSI activity. Addition of vanillic acid to the growth medium significantly affected the QS regulated production of biofilm and virulence factors in a concentration dependent mode in S. marcescens CI, ATCC 14756 and MG1. Furthermore vanillic acid increased the survival of Caenorhabditis elegans upon S. marcescens infection. Proteomic analysis and mass spectrometric identification of differentially expressed proteins revealed the ability of vanillic acid to modulate the expression of proteins involved in S-layers, histidine, flagellin and fatty acid production. QSI potential of the vanillic acid observed in the current study paves the way for exploring it as a potential therapeutic candidate to treat S. marcescens infections.

A series of amphiphilic diblock copolypeptides (K 30 -b-F 15 , K 30 -b-F 30 , and K 30 -b-F 45 ) were synthesized via N-carboxy-α-amino-anhydride ring-opening polymerization. The copolypeptides had excellent antibacterial efficacy to both Gram positive (S. aureus) and Gram negative (E. coli) bacteria. The minimum inhibitory concentrations (MICs) against E. coli and S. aureus are 8 μg mL -1 and 2 μg mL -1 , respectively, lower than most natural and artificial antimicrobial peptides (AMPs). The morphological changes of the bacteria treated with diblock copolypeptides were investigated by transmission electron microscopy; the results proved that the diblock copolypeptides had a similar antibacterial pore-forming mechanism to natural cationic peptides. This was confirmed by laser scanning confocal microscope images. CCK-8 results and the MICs showed that the diblock copolypeptides have high selectivity to bacteria, which suggested that the diblock copolypeptides could be excellent candidates to replace traditional antibiotics in future., (© 2017 Wiley Periodicals, Inc.)

The impact of substituents on the photochemical and biological properties of tetraphenylporphyrin-based photosensitizers for photodynamic therapy of cancer (PDT) as well as photodynamic inactivation of microorganisms (PDI) was examined. Spectroscopic and physicochemical properties were related with therapeutic efficacy in PDT of cancer and PDI of microbial cells in vitro. Less polar halogenated, sulfonamide porphyrins were most readily taken up by cells compared to hydrophilic and anionic porphyrins. The uptake and PDT of a hydrophilic porphyrin was significantly enhanced with incorporation in polymeric micelles (Pluronic L121). Photodynamic inactivation studies were performed against Gram-positive (S. aureus, E. faecalis), Gram-negative bacteria (E. coli, P. aeruginosa, S. marcescens) and fungal yeast (C. albicans). We observed a 6 logs reduction of S. aureus after irradiation (10 J/cm2) in the presence of 20 μM of hydrophilic porphyrin, but this was not improved with incorporation in Pluronic L121. A 2-3 logs reduction was obtained for E. coli using similar doses, and a decrease of 3-4 logs was achieved for C. albicans. Rational substitution of tetraphenylporphyrins improves their photodynamic properties and informs on strategies to obtain photosensitizers for efficient PDT and PDI. However, the design of the photosensitizers must be accompanied by the development of tailored drug formulations.

Aims: To evaluate the antibiofilm potential of water-soluble Moringa oleifera seed lectin (WSMoL) on Serratia marcescens and Bacillus sp., Methods and Results: WSMoL inhibited biofilm formation by S. marcescens at concentrations lower than 2·6 μg ml -1 and impaired bacterial growth at higher concentrations, avoiding biofilm formation. For Bacillus sp., the lectin inhibited bacterial growth at all concentrations. The antibiofilm action of WSMoL is associated with damage to bacterial cells. WSMoL did not disrupt preformed S. marcescens biofilms but was able to damage cells inside them. On the other hand, the lectin reduced the number of cells in Bacillus sp. biofilm treated with it. WSMoL was able to control biofilm formation when immobilized on glass surface (116 μg cm -2 ), damaging S. marcescens cells and avoiding adherence of Bacillus sp. cells on glass. The Bacillus sp. isolate is member of Bacillus subtilis species complex and closely related to species of the conspecific 'amyloliquefaciens' group., Conclusion: WSMoL prevented biofilm development by S. marcescens and Bacillus sp. and the antibiofilm effect is also observed when the lectin is immobilized on glass., Significance and Impact of the Study: Taking together, our results provide support to the potential use of WSMoL for controlling biofilm formation by bacteria., (© 2017 The Society for Applied Microbiology.)

The emergence and spread of carbapenem-resistant gram-negative bacteria poses a serious threat to human health worldwide. Currently, little is known about the molecular mechanisms underlying carbapenem resistance and their prevalence among gram-negative bacteria in Egypt. In this study, we analyzed carbapenemase production in gram-negative bacteria isolated from hospitalized patients in Egypt in 2014. All isolates were subjected to phenotypic and genotypic susceptibility testing for carbapenem resistance. Our results indicated a high level of carbapenem-resistant gram-negative bacteria in Egypt, with 50.8% of the isolates harboring at least one carbapenem resistance gene. OXA-48-like and NDM-1 were the most prevalent carbapenemases, being detected in 49.2%, and 47.7% of carbapenemase-positive isolates, respectively, whereas Verona integron-encoded metallo-β-lactamase (VIM) was detected in only 26.2% of carbapenemase-positive isolates. This study reports for the first time carbapenemase-producing Serratia marcescens, Morganella morganii, and bla VIM-1-like -producing Pseudomonas aeruginosa in Egypt. It is also the first demonstration of the coexistence of different carbapenemases, being detected in 21.5% of carbapenemase-positive isolates. Effective antibiotic supervision, regional surveillance, and early detection of carbapenemase producers are imperative to prevent their future spread to epidemic levels.

Fenamiphos is a systematic nematicide-insecticide used extensively for the control of soil nematodes. Fenamiphos and oxidation products have been known to induce water pollution, soil pollution and ecotoxicological effects on aquatic organisms, as well as heath issues. This contaminant can be removed by phytoremediation. Herein, we tested several strategies to improve the effectiveness of this technology. A combination of G. max plus Pseudomonas fluorescens was more efficient than G. max plus Serratia marcescens or G. max alone in degrading fenamiphos to other metabolites. Three major metabolites, namely fenamiphos sulfoxide (FSO), fenamiphos sulfone (FSO 2 ) and fenamiphos phenol (F-phenol), were detected in roots and leaves in which G. max amended with P. fluorescens or amended with S. marcescens produced a significant accumulation of FSO and FSO 2 with higher amounts than for G. max alone. Leaf concentrations of FSO were always higher than in the roots, while FSO 2 accumulated significantly more in G. max roots than in G. max leaves. In soil treated with fenamiphos, G. max roots and leaves alone, and in combined effects of plant and microorganisms, resulted in the disappearance of fenamiphos and the appearance of F-SO, F-SO 2 and F-phenol, which in turn caused toxic stress in G. max and the resulting production of reactive oxygen species such as H 2 O 2 with higher content and an increase in antioxidant GPX activity. Although a batch equilibrium technique showed that use of SiO 2 resulted in the efficient removal of fenamiphos when compared with other treatments for removing adsorbed fenamiphos from soil, a fewer amount of fenamiphos was removed by G. max L. with SiO 2 . H 2 O 2 content and GPX activity increased in G. max under fenamiphos treatment and its degradation products, while amended G. max with SiO 2 or Argal led to a decrease in GPX activity and H 2 O 2 content., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Introduction/background: Xeroform ® is a petrolatum-based fine mesh gauze containing 3% bismuth tribromophenate. Bismuth, similar to other metals, has antimicrobial properties. Xeroform ® has been used for decades in burn and plastic surgery as a donor site dressing and as a covering for wounds or partial thickness burns. Despite this, the antimicrobial spectrum of Xeroform ® remains largely unknown. We examined the in-vitro efficacy of Xeroform ® against common burn pathogens using zone-of-inhibition methodology in a commercial research facility., Methods/design: Pure strains of 15 common burn pathogens including Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus (MSSA), Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterobacter cloacae, Escherichia coli, Candida albicans, Vancomycin resistant Enterococcus, Acinetobacter baumennii, Klebsiella pneumonia, Extended spectrum beta-lactamase producing Klebsiella, Beta hemolytic Streptococcus pyogenes, Proteus mirabilis, Serratia marcescens, and Salmonella enterica ssp. Enterica were inoculated at a strength of 10 6 -10 10 CFU/ml onto appropriate agar plates. A sterile 1 in 2 Xeroform ® square was placed in the center of each plate, and the Zone of Inhibition (ZOI) was measured following 18-24h of incubation at 37°C. A second bismuth pharmaceutical (bismuth subsalicylate, Pepto-Bismol ® ) was then tested using the same methodology against the same strains of MRSA, MSSA, E. coli, K. pneumonia and S. marcescens. Finally, 3% w/v bismuth tribromophenate in glycerol suspension was tested against 13 burn pathogens for antimicrobial activity independent of the Xeroform ® dressing by measure of Zone of Inhibition., Results/findings: For Xeroform ® , none of the fifteen pathogens had a measurable zone of inhibition on any plate. Bismuth subsalicylate showed a zone of inhibition for MSSA in 3 plates (mean of 47.2mm), in one of three plates for MRSA (13.8mm), and in one of three plates for S. marcesens (89.6mm). There was no zone of inhibition seen for K. pneumonia or E. coli. Bismuth tribromophenate, when not bound to Xeroform ® showed activity against 12 of 13 pathogens., Conclusions/implications: While bismuth subsalicylate, and bismuth tribromophenate unbound to Xeroform ® demonstrate antimicrobial activity, it appears that Xeroform ® dressings do not. The utility of Xeroform ® in burn medicine may relate more to use as an impervious dressing than to antimicrobial effect. Donor sites are clean surgical wounds and clean partial thickness burns may have minimal colonization present. In such circumstances, an inactive and impervious dressing may be all that is necessary to promote wound healing., (Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.)

Escherichia coli strains resistant to extended-spectrum cephalosporins (ESC) are widely distributed in Norwegian broiler production, and the majority harbor transferable IncK or IncI1 plasmids carrying bla CMY-2 Persistent occurrence in broiler farms may occur through the survival of ESC-resistant E. coli strains in the farm environment, or by transfer and maintenance of resistance plasmids within a population of environmental bacteria with high survival abilities. The aim of this study was to determine the transferability of two successful bla CMY-2 -carrying plasmids belonging to the incompatibility groups IncK and IncI1 into E. coli and Serratia species recipients. Initially, conjugative plasmid transfer from two E. coli donors to potential recipients was tested in an agar assay. Conjugation was further investigated for selected mating pairs in surface and planktonic assays at temperatures from 12°C to 37°C. Transfer of plasmids was observed on agar, in broth, and in biofilm at temperatures down to 25°C. The IncK plasmid was able to transfer into Serratia marcescens , and transconjugants were able to act as secondary plasmid donors to different E. coli and Serratia species recipients. All transconjugants displayed an AmpC phenotype corresponding to the acquisition of bla CMY-2 In summary, the results indicate that the IncK plasmid may transfer between E. coli and Serratia spp. under conditions relevant for broiler production. IMPORTANCE Certain bla CMY-2 -carrying plasmids are successful and disseminated in European broiler production. Traditionally, plasmid transferability has been studied under conditions that are optimal for bacterial growth. Plasmid transfer has previously been reported between E. coli bacteria in biofilms at 37°C and in broth at temperatures ranging from 8 to 37°C. However, intergenus transfer of bla CMY-2 -carrying plasmids from E. coli to environmental bacteria in the food-processing chain has not been previously studied. We demonstrate that bla CMY-2 -carrying plasmids are capable of conjugative transfer between different poultry-associated bacterial genera under conditions relevant for broiler production. Transfer to Serratia spp. and to hosts with good biofilm-forming abilities and with the potential to act as secondary plasmid donors to new hosts might contribute to the persistence of these resistance plasmids. These results contribute to increased knowledge of factors affecting the persistence of ESC resistance in broiler production and can provide a basis for improvement of routines and preventive measures., (Copyright © 2017 Mo et al.)