fimA Gene Research Articles

Novel In Vivo Assessment of Antimicrobial Efficacy of Ciprofloxacin Loaded Mesoporous Silica Nanoparticles against Salmonella typhimurium Infection.

Salmonella enterica serovar Typhimurium (S. typhimurium) is known for its intracellular survival, evading the robust inflammation and adaptive immune response of the host. The emergence of decreased ciprofloxacin (CIP) susceptibility (DCS) requires a prolonged antibiotic course with increased dosage, leading to threatening, adverse effects. Moreover, antibiotic-resistant bacteria can persist in biofilms, causing serious diseases. Hence, we validated the in vitro and in vivo efficacy of ciprofloxacin-loaded mesoporous silica nanoparticles (CIP–MSN) using a rat model of salmonella infection to compare the oral efficacy of 5 mg/kg body weight CIP–MSN and a traditional treatment regimen with 10 mg/kg CIP postinfection. Our results revealed that mesoporous silica particles can regulate the release rate of CIP with an MIC of 0.03125 mg/L against DCS S. typhimurium with a greater than 50% reduction of biofilm formation without significantly affecting the viable cells residing within the biofilm, and a sub-inhibitory concentration of CIP–MSN significantly reduced invA and FimA gene expressions. Furthermore, oral supplementation of CIP–MSN had an insignificant effect on all blood parameter values as well as on liver and kidney function parameters. MPO and NO activities that are key mediators of oxidative stress were abolished by CIP–MSN supplementation. Additionally, CIP–MSN supplementation has a promising role in attenuating the elevated secretion of pro-inflammatory cytokines and chemokines in serum from S. typhimurium-infected rats with a reduction in pro-apoptotic gene expression, resulting in reduced S. typhimurium-induced hepatic apoptosis. This counteracted the negative effects of the S. typhimurium challenge, as seen in a corrected histopathological picture of both the intestine and liver, along with increased bacterial clearance. We concluded that, compared with a normal ciprofloxacin treatment regime, MSN particles loaded with a half-dose of ciprofloxacin exhibited controlled release of the antibiotic, which can prolong the antibacterial effect.

Anti-adhesion properties of 4-(adamantyl-1)-1-(1-aminobutyl) benzole against Еscherichia coli

One of the serious problems of medicine is the formation and spread of antibiotic-resistant E. coli strains capable of causing acute and chronic persistent infections due to biofilms. Insufficient effectiveness of antimicrobial chemotherapy in acute inflammatory diseases and the practical absence of drugs with an antibiofilm activity actualize the search for promising compounds and the development of effective and safe drugs on their basis.The aim of this work is to study the effect of 4-(adamantyl-1)-1-(1-aminobutyl) benzole (AM-166) on the adhesive properties of E. coli and the expression of genes that regulate adhesion.The antibiofilm activity of the adamantane-containing compound AM-166 was studied by the sorption of gentian violet on biofilm structures, the hydrophobicity of the E. coli cell surface was assessed by adhesion to a solvent (MATS test), swimming, swarming, and twitching migration – by standard methods. Cell adhesion to the abiotic surface was assessed by the Christensen method, the effect of AM-166 on the expression of the fimA, papC, fliC, and motB genes was investigated using realtime PCR.It was shown that the AM-166 compound disrupts the formation of E. coli biofilm: the biomass decreases at 5.0 MIC by 69.2 %, at 0.5 MIC – by 36.9 %. It was found that AM-166 reduces the hydrophobicity of E. coli cells (by 4.0 % at 0.5 MIC) and adhesion to an abiotic substrate (by 46.0–76.4 %, depending on the incubation time), inhibits twitching migration, and stimulates swarming migration. The diameters of the E. coli mobility zones increased by 1.5 times (0.5 MIC) and 1.2 times (2.0 MIC). Under the action of AM-166, an increase in the expression of the fimA gene, as well as a decrease in the expression of the fliCand motB genes (by 2 times) were recorded. The decrease in papC gene expression was statistically insignificant.Thus, the antibiofilm activity of AM-166 is due to the impaired mobility of microorganisms and altered expression of the fimA, fliC, and motB genes. In the future, it is necessary to study the effect of the adamantane derivative on the Quorum Sensing systems in E. coli.

Molecular Study of Klebsiella Oxytoca Associated with Urinary Tract Infection in Children

Background:There are scarce reports about the association ofKlebsiella oxytoca(K. oxytoca) with urinary tract infection (UTI) in children. We aimed to evaluate the prevalence offimA, mrkA, matBandpilQadhesins genes and extended-spectrum beta-lactamase (ESBL) genesblaCTX-M, blaTEMandblaSHVby polymerase chain reaction (PCR) and to study biofilm formation and antibiotics resistance inK. oxytocafrom children with UTI.Methods:This study was a retrospective cross-sectional study that included 120 children with UTI due toK. oxytoca. The bacteria were subjected to molecular detection offimA, mrkA, matBandpilQadhesins genes and ESBL genesblaCTX-M, blaTEMandblaSHVby PCR. Biofilm capacity was determined by the microtiter plate method.Results:The isolatedK. oxytocahad positive ESBL activity in 45.8% of isolates. About 40% of isolates were biofilm producers. The frequency of adhesion genes amongK. oxytocawas 91.7%, 83.3%, 48.3% and 37.5% formatB, pilQ, fimAandmrkAgenes, respectively. For ESBL genes, the frequency was 38.3%, 36.7% and 33.3% forblaCTX-M, blaSHVandblaTEMgenes, respectively. The commonest genes among ESBL isolates wereblaCTX-M(83.6%),blaSHV(80%) thenblaTEMgene (72.7%). A significant association (p=0.048) was detected between ESBL activity and biofilm formation byK. oxytoca.Conclusion:Present study highlights the emergence ofK. oxytocaas a pathogen associated with UTI in children. There was a high prevalence of adhesin genes and ESBL genes among these isolates. The capacity ofK. oxytocato form biofilm was associated with ESBL production.

Expression of virulence factor genes in co-infections with Trueperella pyogenes isolates and other bacterial pathogens; an in vivo study

Trueperella pyogenes is an opportunistic bacterial pathogen causing several infectious diseases, including metritis, mastitis and abscesses in domestic animals such as dairy cattle. Several virulence proteins are released by T. pyogenes strains contributing to the pathogenic and causing disease potential of this pathogen. So far, many aspects of T. pyogenes pathogenesis are unknown. In this study, expression levels of plo, fimA, nanH and cbpA genes encoding pyolysin, fimbriae, neuraminidase and collagen-binding protein, respectively in T. pyogenes isolated from totally 15 metritis, mastitis and cutaneous abscesses convenience samples in response to co-culture with other pathogens including E. coli, St. dysgalactiae, S. aureus, F. necrophorum and L. plantarum strains in mice study model have been investigated. We found that expression levels of plo, fimA, nanH and cbpA genes in T. pyogenes isolates in response to co-culture with F. necrophorum and E. coli were significantly increased; however, no significant changes was seen in the level of expression of these genes in the isolates in response to co-culture with St. dysgalactiae and S. aureus. Notably, expression of all virulence factor genes was suppressed in T. pyogenes in response to co-culture with L. plantarum. We observed that L. plantarum might be used to prevent infectious diseases caused by T. pyogenes.

A Virulent Trueperella pyogenes Isolate, Which Causes Severe Bronchoconstriction in Porcine Precision-Cut Lung Slices.

Trueperella pyogenes causes disease in cattle, sheep, goats and swine, and is involved occasionally in human disease worldwide. Most reports implicating T. pyogenes have been associated with clinical cases, whereas no report has focused on pathogenicity of T. pyogenes in mouse models or precision-cut lung slice (PCLS) cultures from swine. Here, we isolated and identified a virulent, β-hemolytic, multidrug-resistant T. pyogenes strain named 20121, which harbors the virulence marker genes fimA, fimE, nanH, nanP and plo. It was found to be highly resistant to erythromycin, azithromycin and medemycin. Strain 20121 was pathogenic in mouse infection models, displaying pulmonary congestion and inflammatory cell infiltration, partial degeneration in epithelial cells of the tracheal and bronchiolar mucosa, a small amount of inflammatory cell infiltration in the submucosa, and bacteria (>104 CFU/g) in the lung. Importantly, we used T. pyogenes 20121 to infect porcine precision-cut lung slices (PCLS) cultures for the first time, where it caused severe bronchoconstriction. Furthermore, dexamethasone showed its ability to relieve bronchoconstriction in PCLS caused by T. pyogenes 20121, highlighting dexamethasone may assist antibiotic treatment for clinical T. pyogenes infection. This is the first report of T. pyogenes used to infect and cause bronchoconstriction in porcine PCLS. Our results suggest that porcine PCLS cultures as a valuable 3D organ model for the study of T. pyogenes infection and treatment in vitro.

Результаты выявления поливирулентных штаммов бактерий Lactobacillus spp. при ассоциативном взаимодействии с простейшими Blastocystis hominis in vivo

The identification of polyvirulent strains of Lactobacillus spp. bacteria with associative interaction with protozoa Blastocystis hominis in vivo was carried out. Lactobacillus spp. and B. hominis strains were obtained from the feces of 396 patients undergoing examination for intestinal dysbiosis. Identification was carried out using microscopic, bacteriological and parasitological methods. 112 reference strains of lactobacilli NK1 and K3SH24 deposited at the Institute of Genetics and Breeding of Industrial Microorganisms were used as control. The degree of virulence of the simplest blastocysts was determined by intraperitoneal administration to white mice (weighing 17.4+1.5 g) 0.5 ml of a culture suspension of the studied microorganisms grown on Suresh medium. Primers to several genes determining the ability to form type 1 fimbriae, type S and P fimbriae, bacterial adhesin intimin and hemolysin were used in the investigation. Testing of 396 Lactobacillus spp. strains isolated from microsymbiocenoses with Blastocystis hominis of varying degrees of virulence showed that the dynamics of detection of pathogenicity genes in lactobacilli increased with an increase in the degree of virulence of protozoa. Most often, in the general pool of lactobacillus strains, the desired amplicons were detected using primers to the fimA gene (up to 67.9%). During associative interaction with moderately and highly virulent blastocysts, an increase in the heterogeneity of the lactobacillus population was revealed, manifested by an increase in the frequency of detection of all studied genetic determinants of pathogenicity, compared with Lactobacillus spp. strains isolated from associations with avirulent B. hominis and in the control group.

Characterization of virulence factors of Salmonella isolated from human stools and street food in urban areas of Burkina Faso

BackgroundThis study was undertaken to identify and functionally characterize virulence genes from Salmonella isolates in street food and stool cultures. From February 2017 to May 2018, clinical and food Salmonella strains were isolated in three regions in Burkina Faso. Salmonella was serotyped according to the White-Kauffmann-Le Minor method, and polymerase chain reaction (PCR) was used to detec invA, spvR, spvC, fimA and stn virulence genes commonly associated with salmonellosis in Sub-Saharan Africa.ResultsA total of 106 Salmonella isolates (77 human stools; 14 sandwiches) was analyzed using a serological identification with an O-group test reagent. The presence of Salmonella was confirmed in 86% (91/106) of the samples were reactive (OMA-positive/OMB-positive). Salmonella serogroup O:4,5 was the most common serogroup detected (40%; 36/91). Salmonella Enteritidis and Typhimurium represented 5.5% (5/91) and 3.3% (3/91), respectively and were identified only from clinical isolates. Furthermore, 14 serotypes of Salmonella (12/91 human strains and 2/15 sandwich strains) were evocative of Kentucky/Bargny serotype. For the genetic profile, 66% (70/106) of the Salmonella had invA and stn genes; 77.4% (82/106) had the fimA gene. The spvR gene was found in 36.8% (39/106) of the isolates while 48.1% (51/106) had the spvC gene. Among the identified Salmonella Enteritidis and Salmonella Typhimurium isolated from stools, the virulence genes detected were invA (3/5) versus (2/3), fimA (4/5) versus (3/3), stn (3/5) versus (2/3), spvR (4/5) versus (2/3) and spvC (3/5) versus (2/3), respectively.ConclusionThis study reports the prevalence of Salmonella serotypes and virulence genes in clinical isolates and in street foods. It shows that food could be a significant source of Salmonella transmission to humans. Our results could help decision-making by the Burkina Faso health authority in the fight against street food-related diseases, in particular by training restaurateurs in food hygiene.

Eugenol exposure in vitro inhibits the expressions of T3SS and TIF virulence genes in Salmonella Typhimurium and reduces its pathogenicity to chickens

BackgroundSalmonella enterica serovar Typhimurium (S. Typhimurium) is a common food-borne pathogen, which has the ability to infect a wide range of hosts. The increasing emergence of drug-resistant strains urgently requires new alternative therapies. Eugenol has been shown to be very effective against drug-resistant strains of Gram-negative and Gram-positive bacteria. The purpose of this study is to explore the effects of eugenol on the virulence factors and pathogenicity of S. Typhimurium. MethodsThe antibacterial activity of eugenol was investigated via the changes of cell morphology, fimbriae related-genes and virulence factors of S. Typhimurium, then the pathogenicity of S. Typhimurium pretreated by eugenol to chickens was evaluated. ResultsSusceptibility testing showed that eugenol possessed significant antimicrobial activity. Scanning electron microscope analysis showed eugenol treatment deformed the morphology with damaged fimbriae structure of S. Typhimurium. Real time PCR assay confirmed eugenol significantly down-regulated the expressions of virulence factors (hilA, hilD, sipA, sipC, spiC, misL) of Type III secretion system (T3SS) and adherence genes (fimA, fimH, fimD, fimY, fimZ, stm0551) of Type I fimbriae (TIF). Animal experiment proved that the pathogenicity of S. Typhimurium exposed by eugenol was reduced, which was evidenced by the higher survival rate, weight gains and organs indexes, the lower bacterial loads in organs. Meanwhile, the duodenal histopathological changes were mitigated, with a significantly decline in the expressions of TNF-α, IL-6 and IL-18. ConclusionIn summary, eugenol pretreatment may alleviate the pathogenicity of the S. Typhimurium to chickens via wrecking the fimbriae and inhibiting the mRNA expressions of virulence factors and adhesion molecules. These data dedicated the potential mechanisms of eugenol against S. Typhimurium in vitro.

Virulence genes and enterobacterial repetitive intergenic consensus region (ERIC) profiling reveals highly diverse genetic population among avian strains of Pasteurella multocida

Pasteurella multocida is a multispecies pathogen with certain host specific capsular types but interspecies transmission cannot be overlooked. Knowing the diversity of P. multocida in a geographical location is essential to formulate a vaccination programme. Diversity among the P. multocida isolates from different avian species recovered in the state of Tamil Nadu, India was studied using enterobacterial repetitive intergenic consensus region (ERIC)-PCR and virulence gene profiling (VP). Capsular typing revealed that 44 (97.78%) strains belonged to capsular type A while only one (2.22%) strain belonged to capsular type B. ERIC-PCR analysis showed eight different clusters and four individual strains. The index of discrimination (D value) was found to be 0.8899. Virulence profiling showed that genes fimA, pfhA, hsf-2 and pmHAS were found in 100% of the strains while ompH, omp87, ompA, plpB, sodA, sodC, ptfA, hsf-1, exbB, fur, hgbA and hgbB were found in ≥90% of the strains. Dermonecrotoxin gene toxA was present only in 4.44% of the strains, while nanH in 68.89% and nanB in 88.89% of the strains. One strain each from turkey and Guinea fowl had toxA gene. Correlation analysis revealed a positive correlation between ptfA and hgbA gene, exbB and fur gene, ptfA and sodC gene, exbB and hsf-1 gene, ompA and ompH gene. Majority of duck strains clustered together both in ERIC and virulence gene profiles. Turkey strains were highly diverse with different VPs and ERIC-PCR patterns.

Phenotypic and molecular evaluation of biofilm formation in Klebsiella pneumoniae carbapenemase (KPC) isolates obtained from a hospital of Pelotas, RS, Brazil.

Introduction. A significant cause of mortality in the intensive care unit (ICU) is multidrug-resistant (MDR) Gram-negative bacteria, such as Klebsiella pneumoniae carbapenemase (KPC). Biofilm production is a key factor in KPC colonization and persistence in the host, making the treatment difficult.Gap Statement. The aim of this study was to evaluate the antibiotic resistance, molecular and phenotypic biofilm profiles of 12 KPC isolates associated with nosocomial infection in a hospital in Pelotas, Rio Grande do Sul, Brazil.Methodology. Clinical isolates were obtained from different sources, identified and characterized by antibiotic resistance and carbapenemase synthesis following the Clinical and Laboratory Standards Institute (CLSI) guidelines. Polymerase chain reaction (PCR) was used to evaluate the presence of carbapenemase (blaKPC) and biofilm formation-associated genes (fimA, fimH, rmpA, ecpA, mrkD and wabG). Additionally, phenotypic evaluation of in vitro biofilm formation capacity was evaluated by Congo red agar (CRA) assay and the crystal violet staining method.Results. The 12 isolates evaluated in this study presented the blaKPC gene and were positive for synthesizing carbapenemases in vitro. In the carbapenem class, 83.3 % isolates were resistant and 16.7 % intermediately resistant to imipenem and meropenem. Molecular analyses found that the fimA and wabG genes were detected in 75 % of isolates, while fimH and ecpA were detected in 42 % and mrkD were detected in 8.3 % (1). The CRA assay demonstrated that all isolates were slime producers and 91.7 % (11) of isolates were classified as strong and 8.3 % (1) as moderate biofilm producers by the crystal violet staining method. The optical density (OD540nm) for strong biofilm formers ranged from 0.80±0.05 to 2.47±0.28 and was 0.55±0.12 for moderate biofilm formers.Conclusion. Our study revealed a high level of antibiotic resistance and biofilm formation in KPC isolates obtained from a hospital in Pelotas, RS, Brazil.

Molecular diversity survey on diarrheagenic Escherichia coli isolates among children with gastroenteritis inFars, Iran.

Aim: To differentiate Escherichia coli isolates from diarrheal pediatric patients in clinical laboratories. Materials & methods: Patients with watery diarrhea were selected for sampling and tested for diarrheagenic E. coli(DEC)by APIkit. DEC isolates were tested for phylotyping, pathotyping and presence of determined virulence-encoding genes by specific molecular methods. Results: About 50% of isolates were detected as DECs (>55and >31% were categorized B2 and D phylotypes respectively). Enterotoxigenic E. coli was the most and enteroinvasive E. coli was the lowest prevalent pathotypes. csgand fim genes were the most present virulence factors. Conclusion: Typing of E. coli isolates from stool specimens will help to determine the diversity of diarrheal pathogens and take proper decisions to reduce the health burden of diarrheal diseases.

An in Vitro Study of Molecular Effects of a Combination Treatment with Antibiotics and Nanofluid Containing Carbon Nano-tubes on Klebsiella pneumoniae.

Background:We aimed to prepare a nanofluid, containing f-MWCNTs, and investigate the antibacterial efficacy of f-MWCNTs+ ciprofloxacin (cip) on Klebsiella pneumoniae by evaluating the virulence gene expression.Methods:This study was carried out from 2019 to 2020, in the Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran. The nanofluid containing antibiotic and f-MWCNTs were prepared by the ultrasonic method. The minimum inhibitory concentrations (MICs) of ciprofloxacin and f-MWCNTs were determined using the broth micro dilution MIC tests. For examining the antibacterial effects, the expression level of virulence genes, under the influence of f-MWCNTs, was evaluated by a real-time PCR.Results:The effect of 8 μg/ml ciprofloxacin + 400 μg/ml f-MWCNTs, completely inhibited the growth of the resistant isolate of K. pneumoniae, while, in the ATCC 700,603 isolate, 2 μg/ml ciprofloxacin with 100 μg/ml f-MWCNT could inhibit a bacterial growth. In the resistant K. pneumoniae clinical isolate, after f-MWCNT+cip treatment, the expression of fimA, fimD, wza, and wzi genes was significantly downregulated, compared to the ciprofloxacin treatment, and upregulated, compared to the negative control. For the ATCC 700,603 isolate treated with f-MWCNT+cip, the expression of fimA, fimD and wza virulence genes showed upregulation, compared to the negative control and downregulated in comparison with the ciprofloxacin treatment.Conclusion:Simultaneous treatment of resistant isolate of K. pneumoniae with f-MWCNTs +antibiotic could improve the effectiveness of antibiotic at lower doses, due to the reduced expression of virulence genes in comparison with antibiotic treatment, besides the increased cell wall permeability to antibiotics.

Whole genome sequencing and protein structure analyses of target genes for the detection of Salmonella

Rapid and sensitive detection of Salmonella is a critical step in routine food quality control, outbreak investigation, and food recalls. Although various genes have been the targets in the design of rapid molecular detection methods for Salmonella, there is limited information on the diversity of these target genes at the level of DNA sequence and the encoded protein structures. In this study, we investigated the diversity of ten target genes (invA, fimA, phoP, spvC, and agfA; ttrRSBCA operon including 5 genes) commonly used in the detection and identification of Salmonella. To this end, we performed whole genome sequencing of 143 isolates of Salmonella serotypes (Enteritidis, Typhimurium, and Heidelberg) obtained from poultry (eggs and chicken). Phylogenetic analysis showed that Salmonella ser. Typhimurium was more diverse than either Enteritidis or Heidelberg. Forty-five non-synonymous mutations were identified in the target genes from the 143 isolates, with the two most common mutations as T ↔ C (15 times) and A ↔ G (13 times). The gene spvC was primarily present in Salmonella ser. Enteritidis isolates and absent from Heidelberg isolates, whereas ttrR was more conserved (0 non-synonymous mutations) than ttrS, ttrB, ttrC, and ttrA (7, 2, 2, and 7 non-synonymous mutations, respectively). Notably, we found one non-synonymous mutation (fimA-Mut.6) across all Salmonella ser. Enteritidis and Salmonella ser. Heidelberg, C → T (496 nt postion), resulting in the change at AA 166 position, Glutamine (Q) → Stop condon (TAG), suggesting that the fimA gene has questionable sites as a target for detection. Using Phyre2 and SWISS-MODEL software, we predicted the structures of the proteins encoded by some of the target genes, illustrating the positions of these non-synonymous mutations that mainly located on the α-helix and β-sheet which are key elements for maintaining the conformation of proteins. These results will facilitate the development of sensitive molecular detection methods for Salmonella.

Porphyromonas gingivalis FimA and Mfa1 fimbriae: Current insights on localization, function, biogenesis, and genotype.

In general, the periodontal pathogen Porphyromonas gingivalis expresses distinct FimA and Mfa1 fimbriae. Each of these consists of five FimA–E and five Mfa1–5 proteins encoded by the fim and mfa gene clusters, respectively. The main shaft portion comprises FimA and Mfa1, whereas FimB and Mfa2 are localized on the basal portion and function as anchors and elongation terminators. FimC–E and Mfa3–5 participate in the assembly of an accessory protein complex on the tips of each fimbria. Hence, they serve as ligands for the receptors on host cells and other oral bacterial species. The crystal structures of FimA and Mfa1 fimbrial proteins were recently elucidated and new insights into the localization, function, and biogenesis of these proteins have been reported. Several studies indicated a correlation between P. gingivalis pathogenicity and the fimA genotype but not the mfa1 genotype. We recently revealed polymorphisms of all genes in the fim and mfa gene clusters. Intriguingly, mfa5 occurred in numerous different forms and underwent duplication. Detailed structural and functional knowledge of the fimbrial proteins in the context of the entire filament could facilitate the development of innovative therapeutic strategies for structure-based drug design.

Molecular Analysis of fimA Operon Genes among UPEC Local Isolates in Baghdad City.

Specialized Escherichia coli (E. coli) isolates, called uropathogenic E. coli (UPEC), cause most of urinary tract infections (UITs). Once bacteria reached the urinary tract of the host, they have to adhere to the host cell for the colonization. For this purpose, bacteria have different structures including fimbrial adhesins. Most of the UPECs contain type 1 fimbriae encoded by fim operon (fimB, E, A, I, C, D, F, G, H) which is responsible for the adhesive ability in these isolates. Ninety-four isolates of UPEC were obtained from UTI patients in Baghdad hospitals and their diagnosis were confirmed by the PCR method using 16srDNA as a housekeeping gene. The UPEC isolates were tested for their ability of adherence to the urothelialcells obtained from the mid-stream urine from healthy women. Fifty isolates were subjected to detect type1 fimbriae genes (fimA operon) using specific primers followed by sequencing the amplified fragment which they were analyzed by Geneious software. The results confirm that all the isolates were E. coli according to the genetic analysis by the PCR test, and also, the ability of attachment for all isolates were approved (100%). For type 1 fimbriae, the findings figured out that 100% of the isolates harbored fimA,fimI, fimC, fimD, fimG and fimH genes; while 96% of them were positive for fimB, fimF,and 82% of the isolates were positive for fimE. This result exhibited a higher prevalence of fim genes, as the attachment ability was 100%. Approximately, all UPEC have type 1fimbrial genes, so it could be used as a genetic marker in the investigation of E. coli adhesion ability.

Exploring Photoactivated Disinfection-Induced Bystander Effects on Microbial Biofilms of Aggregatibacter actinomycetemcomitans.

Photoactivated disinfection (PAD) has been indicated as one of the potential methods for the initial periodontal therapy in periodontitis and peri-implantitis, which may have bystander effects on the viability of off-target cells. In this article, we evaluated the effects of PAD-induced bystander on biofilm formation ability, metabolic activity, and gene expression level of Aggregatibacter actinomycetemcomitans as one of the bacteria involved in causing periodontitis and peri-implantitis. Bystander effects induced by bacterial cell suspension (BCST) obtained from treated A. actinomycetemcomitans culture with indocyanine green (ICG)-PAD on biofilm formation of A. actinomycetemcomitans were determined using microbial viability assay. Additionally, metabolic activity and changes in gene expression of fimA were assessed using the XTT reduction method and quantitative real-time PCR (qRT-PCR) assay, respectively. The results revealed that 1000 and 125 μg/mL of ICG combined with diode laser irradiation for 1 min were significant and sub-significant reduction doses of ICG-PAD, respectively, versus A. actinomycetemcomitans. The biofilm formation ability, metabolic activity, as well as, expression level of fimA gene in A. actinomycetemcomitans were significantly reduced after treatment by a significant reduction dose of ICG-PAD-induced bystander effects (P<0.05). ICG-PAD could significantly reduce the microbial population, cell metabolic activity, and gene expression through the bystander effects and could enhance the efficiency of PAD as an adjunct approach for the nonsurgical treatment of periodontitis and peri-implantitis.

Antibacterial and antibiofilm efficacy of Ag NPs, Ni NPs and Al2O3 NPs singly and in combination against multidrug-resistant Klebsiella pneumoniae isolates

BackgroundAlthough traditional antibiotic therapy provided an effective approach to combat pathogenic bacteria, the long-term and widespread use of antibiotic results in the evolution of multidrug-resistant bacteria. Recent progress in nanotechnology offers an alternative opportunity to discover and develop novel antibacterial agents. MethodsA total of 51 K. pneumoniae strains were collected from several specimens of hospitalized patients and identified by two parallel methods (biochemical tests and Vitek-2 system). The antibiotic sensitivity of isolates was evaluated by disk diffusion antibiogram and Vitek-2 system. The biofilms formation ability of antibiotic-resistant strains was examined by microtiter plate and tube methods based on crystal violet staining. The molecular technique was used to determine key genes responsible for biofilms formation of clinical isolates. The antibacterial and antibiofilm activities of Ag NPs, Ni NPs, Al2O3 NPs singly (NPs) and in combination (cNPs) were investigated against selected strains using standard methods. Moreover, the cytotoxicity of NPs was evaluated on mouse neural crest-derived (Neuro-2A) cell line. ResultsThe results of bacterial studies revealed that more than 80 % of the isolates were resistant to commonly used antibiotics and about 95 % of them were able to form biofilms. Moreover, the presence of fimA and mrkA genes were determined in all biofilm-producing strains. The results of antibacterial and antibiofilm activities of NPs and cNPs demonstrated the lower MIC and MBEC values for Al2O3 NPs singly as well as for Ag/Ni cNPs and Ag/Al2O3 cNPs in combination, respectively. Overall, the inhibitory effects of cNPs were superior to NPs against all strains. Furthermore, the results of the checkerboard assays showed that Ag NPs act synergistically with two other NPs against multidrug-resistant Klebsiella pneumoniae (MDR-K. pneumoniae) isolates. The in vitro cytotoxicity assay revealed no significant toxicity of NPs against Neuro-2A cells. ConclusionIn the present study, the combination of Ag NPs, Ni NPs, and Al2O3 NPs were used against MDR-K. pneumoniae strains and antibacterial and antibiofilm activities were observed for Ag/Ni cNPs and Ag/Al2O3 cNPs.

English

Trueperella pyogenes is considered as a causative agent of many infections, such as mastitis, endometritis, pneumonia, liver abscessation. T. pyogenes can express several virulence genes such as plo, fimA, cbpA, nanH and nanP contributing to its pathogenicity. The aim of this study was to provide an investigation about antimicrobial resistance, as well as virulence genes distribution and gene cassettes among T. pyogenes isolates from dairy cows with clinical mastitis. The susceptibility to different antimicrobial agents was determined by the Broth Microdilution Method, and virulence genes and gene cassette was detected by polymerase chain reactions (PCRs). There are 10.49% (17/162) of milk samples from dairy cows with mastitis were positive for T. pyogenes. High levels of resistance were found to clindamycin (23.53%), oxytetracycline (23.53%), ciprofloxacin (47.06%), sulfamethoxazole/trimethoprim (100%). Moreover, all isolates carried class I integrons, and gene cassette arrays were aadA9 (2/17) or aadA5-dfrA17 (3/17). Finally, all isolates harbored plo nanH and fimA genes, but other genes encoding virulence genes including fimC, fimE, nanP and cbpA are ranged from 47.06% to 88.23%. Our study showed T. pyogenes isolates from dairy cows with clinical mastitis were susceptible to β-lactams. In addition, all seven virulence genes occurred in isolates, and plo, nanH, and fimA gene showed a significantly higher frequency in T. pyogenes of the Liaoning Province, China.

Xylitol Inhibits Growth and Blocks Virulence in Serratia marcescens

Serratia marcescens is an opportunistic nosocomial pathogen and causes wound and burn infections. It shows high resistance to antibiotics and its pathogenicity is mediated by an arsenal of virulence factors. Another therapeutic option to such infections is targeting quorum sensing (QS), which controls the expression of different S. marcescens virulence factors. Prevention of QS can deprive S. marcescens from its bacterial virulence without applying stress on the bacterial growth and facilitates the eradication of the bacteria by immunity. The objective of the current study is to explore the antimicrobial and antivirulence activities of xylitol against S. marcescens. Xylitol could inhibit the growth of S. marcescens. Sub-inhibitory concentrations of xylitol could inhibit biofilm formation, reduce prodigiosin production, and completely block protease activity. Moreover, xylitol decreased swimming motility, swarming motility and increased the sensitivity to hydrogen peroxide. The expression of rsmA, pigP, flhC, flhD fimA, fimC, shlA bsmB, and rssB genes that regulate virulence factor production was significantly downregulated by xylitol. In silico study showed that xylitol could bind with the SmaR receptor by hydrophobic interaction and hydrogen bonding, and interfere with the binding of the natural ligand with SmaR receptor. An in vivo mice survival test confirmed the ability of xylitol to protect mice against the virulence of S. marcescens. In conclusion, xylitol is a growth and virulence inhibitor in S. marcescens and can be employed for the treatment of S. marcescens wound and burn infections.

The emergence of extended-spectrum β-lactamase (ESBL)-producing Salmonella London isolates from human patients, retail meats and chickens in southern China and the evaluation of the potential risk factors of Salmonella London

Salmonella is a major foodborne pathogen that causes a broad range of infection in humans and animals. This research was undertaken to investigate the antimicrobial resistance, virulence genes and genotyping of the extended-spectrum β-lactamase (ESBL)-producing Salmonella London (S. London) isolates originating from human patients, retail meats and chickens in southern China. The high antimicrobial resistance rates to trimethoprim/sulfamethoxazole (100%), methoxypyrimidine (100%), sulfaisoxazole (100%), ampicillin (73.68%) and amoxicillin (63.16%) were observed among a total of 19 S. London isolates, and the particular concern is that all isolates exhibited multidrug resistance (MDR). The ESBL-positive phenotype, which is resistant to antibiotics such as ampicillin, ceftazidime and cefotaxime, was observed in the isolates (15/19). These strains harbor the emerging ESBL-coding genes blaSHV, blaTEM-1, blaCTX-M and blaOXA, and co-harbor the virulence genes stn, invA, sseL and virK. In addition, the predominant genotypic virulence profile was characterized by the presence of stn, fimA, virK, invA, sseL, mgtC, siiE and sopB genes in the strains. The profiles of enterobacterial repetitive intergenic consensus (ERIC)-PCR revealed that S. London isolates with genetic diversity were widely disseminated. This study highlights the potential threat to public health posed by the foodborne transmission of the multidrug-resistant S. London isolates from diverse sources.