• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.651-661
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• 2019

Targeting the pathogen viability using drugs is associated with development of drug resistance due to selective pressure. Hence, there is an increased interest in developing agents that target bacterial virulence. In this study, the inhibitory effect of ciclopirox, an antifungal agent with iron chelation potential, on the microbial virulence factors was evaluated in 26 clinical MDR Pseudomonas aeruginosa isolates collected from Alexandria Main University Hospital, a tertiary hospital in Egypt. Treatment with 9 ㎍/ml ciclopirox inhibited the hemolytic activity in 70% isolates, reduced pyocyanin production, decreased protease secretion in 46% isolates, lowered twitching and swarming motility, and decreased biofilm formation by 1.5- to 4.5-fold. The quantitative real-time PCR analysis revealed that treatment with ciclopirox downregulated the expression levels of alkaline protease (aprA) and pyocyanin (phzA1). Ciclopirox is used to treat hematological malignancies and the systemic administration of ciclopirox is reported to have adequate oral absorption with a satisfactory drug safety profile. It is important to calculate the appropriate clinical dose and therapeutic index to reposition ciclopirox from a topical antifungal agent to a promising virulence-modifying agent agent against P. aeruginosa, a problematic Gram-negative pathogen.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.190-200
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• 2016

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) in rice (Oryza sativa L.). In this study, we investigated the effect of a mutation in opsX (XOO1056), which encodes a saccharide biosynthesis regulatory protein, on the virulence and bacterial chemotaxis of Xoo. We performed DNA micro-array analysis, which showed that 63 of 2,678 genes, including genes related to bacterial motility (flagellar and chemotaxis proteins) were significantly downregulated ($<\;-2\;log_2$ fold changes) by the mutation in opsX. Indeed, motility assays showed that the mutant strain was nonmotile on semisolid agar swarm plates. In addition, a mutant strain (opsX::Tn5) showed decreased virulence against the susceptible rice cultivar, IR24. Quantitative real-time RT-PCR reaction was performed to confirm the expression levels of these genes, including those related to flagella and chemotaxis, in the opsX mutant. Our findings revealed that mutation of opsX affects both virulence and bacterial motility. These results will help to improve our understanding of Xoo and provide insight into Xoo-rice interactions.

• International Journal of Oral Biology
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• v.43 no.4
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• pp.171-175
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• 2018

Quorum sensing (QS) is a cell density-dependent communication mechanism between bacteria through small signaling molecules. When the number of QS signaling molecules reaches a threshold, they are transported back into the cells or recognized by membrane-bound receptors, triggering gene expression which affects various phenotypes including bioluminescence, virulence, adhesion, and biofilm formation. These phenotypes are beneficial for bacterial survival in harsh environments. This review summarizes the application of QS inhibitors for control of biofilm formation and virulence expression of periodontal pathogens.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.253-260
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• 2000

The virulence(vir) genes in Ti plasmid at Agrobacterium tumefaciens are expressed by a phenolic compound synthesized at plant wound site. The vir genes inducing abilities of 8 phenolic compounds were tested using three wild type strains of A. tumefaciens. It was also investigated how the levels of vir gene expression among the strains tested could be related to the kinds of specific phenolic compounds. Five phenolic compounds like as 4-hydroxyacetophenone, phenol, catechol, resorcinol, and vanillin had exhibited a strong effect on the vir gene expression of A. tumefaciens MW102 whereas they did not be either non-functional or weakly inducible to the vir gene expression of other strains i.e. A. tumefaciens MW105 and MW108. Furthermore, the vir gene of A. tumefaciens MW102 was lowly expressed by acetosyringone that exposed an strong effect on the vir gene induction of other two strains. Thus, it appeared that the vir gene inducing abilities were differed by the kinds of phenolic compounds and Ti plasmids. In conclusion, we suppose that a change in vir gene inducing ability could be resulted from a difference of sensor protein expressed by vir A gene.

• Proceedings of the Microbiological Society of Korea Conference
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• 2009.05a
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• pp.137-138
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• 2009

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.220-226
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• 2014

Sixty-seven Vibrio parahaemolyticus isolates from surface seawater from the Wando area, on the southern coast of Korea, were analyzed for their susceptibility to 15 different antimicrobials and the presence of virulence genes. According to the disk diffusion susceptibility test, all of the strains studied were resistant to ampicillin and oxacillin, while decreasing percentages were resistant to vancomycin (64.2%), streptomycin (56.7%), amikacin (31.3%), kanamycin (22.3%), cephalothin (20.9%), erythromycin (10.4%), ciprofloxacin (4.5%), and tetracycline (3.0%). All of the strains were susceptible to five antimicrobials: chloramphenicol, gentamycin, nalidixic acid, sulfamethoxazole/trimethoprim, and trimethoprim. Fifty-nine isolates (88.1%) were resistant to three or more classes of antimicrobial and defined as multidrug resistant, and two strains were resistant to seven antimicrobial agents. The minimum inhibitory concentration (MIC) of the 67 V. parahaemolyticus isolates to ampicillin and oxacillin ranged from 512-2,048 and $64-512{\mu}g/mL$, respectively. All 67 isolates were also examined for the presence of the tdh and trh virulence genes using the polymerase chain reaction (PCR). However, no isolates possessed either tdh or trh. The VPA0477 (${\beta}$-lactamase) gene, present in all of the tested strains, was validated as a new specific marker gene in PCR assays for the accurate detection and identification of V. parahaemolyticus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.800-806
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• 2016

In total, 151 Escherichia coli isolates from Ruditapes philippinarum in Gomso Bay were analyzed for their susceptibility to 18 different antimicrobial agents and for genes associated with virulence. For virulence genes, each strain of the isolates was positive for the enterotoxigenic E. coli (ETEC)-specific heat-stable toxin (estA), enteroinvasive E. coli (EIEC)-specific invasion-associated locus (iaa) gene and enteropathogenic E. coli (EPEC)-specific attaching and effacing (eae) gene. According to a disk diffusion susceptibility test, resistance to ampicillin was most prevalent (23.2%), followed by resistance to amoxicillin (22.5%), ticarcillin (20.5%), tetracycline (18.5%), nalidixic acid (12.6%), ciprofloxacin (10.6%), streptomycin (9.9%), and chloramphenicol (6.6%). More than 35.8% of the isolates were resistant to at least one antimicrobial agent, and 19.9% were resistant to four or more classes of antimicrobials; these were consequently defined as multidrug resistant. Minimum inhibitory concentration (MIC) ranges for the antimicrobial resistance of the 15 different antimicrobial agents of 54 E. coli strains were confirmed by varying the concentrations from $32-2,048{\mu}g/mL$. Overall, these results not only provide novel insights into the necessity for seawater and R. philippinarum sanitation in Gomso Bay but they also help to reduce the risk of contamination by antimicrobial-resistant bacteria.

• Journal of Microbiology
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• v.38 no.3
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• pp.117-121
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• 2000

Recent advances in studies of bacterial gene expression and light microscopy show that cell-to cell communication and communication and community behavior are the rule rather than the exception. One type of cell-cell communication, quorum sensing in Gram-negative bacteria involves acyl-homoserine lactone signals. This type of quorum sension represents a dedicated communication system that enables a given species to sense when it has reached a critical population density. and to respond by activating expression of specific genes. The LuxR and LuxI proteins of Vibrio fisheri are the founding members of the acyl-homoserine lactone quorum sensing signal receptor and signal generator families of proteins. Acyl-homeserine lactone signaling in Pseudomonas aeruginosa is one model for the relationship between quorum sensing community behavior, and virulence. In the P. aeruginosa model. quorum sensing is required for normal biofilm maturation and virulence. There are multiple quorum-sensing circuits that control the expression of dozens of specific genes in P. aeruginosa.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.171-178
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• 2017

A series of novel effector molecules secreted by the type three secretion system (T3SS) of Shigella spp. have been reported in recent years. In this study, a proteomic approach was applied to study T3SS effectors systematically. First, proteins secreted by the S. flexneri wild-type strain after Congo Red induction were separated and identified using two-dimensional electrophoresis to display the relative abundance of all kinds of early effectors for the first time. Then, a gene deletion mutant of known virulence repressor (OspD1) and a gene overexpressed mutant of two known virulence activators (MxiE and IpgC) were constructed and analyzed to discover potential late effectors. Furthermore, the supernatant proteins of gene deletion mutants of two known translocators (IpaB and IpaD), which would constantly secrete effectors, were also analyzed. Among all of the secreted proteins identified in our study, IpaH1.4, IpaH_5, and IpaH_7 have not been reported before. These proteomics data of the secreted effectors will be valuable to understand the pathogenesis of S. flexneri.

• Journal of Veterinary Science
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• v.21 no.4
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• pp.54.1-54.11
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• 2020

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of severe infections in humans and animals worldwide. Studies elucidating the population structure, staphylococcal cassette chromosome mec types, resistance phenotypes, and virulence gene profiles of animal-associated MRSA are needed to understand spread and transmission. Objectives: The objective of this study was to determine 1) clonal complexes and spa types, 2) resistance phenotypes, and 3) virulence/resistance gene profiles of MRSA isolated from animals in Switzerland. Methods: We analyzed 31 presumptive MRSA isolates collected from clinical infections in horses, dogs, cattle, sheep, and pigs, which had tested positive in the Staphaurex Latex Agglutination Test. The isolates were characterized by spa typing and DNA microarray profiling. In addition, we performed antimicrobial susceptibility testing using the VITEK 2 Compact system. Results: Characterization of the 31 presumptive MRSA isolates revealed 3 methicillinresistant Staphylococcus pseudintermedius isolates, which were able to grow on MRSA2 Brilliance agar. Of the 28 MRSA isolates, the majority was assigned to CC398 (86%), but CC8 (11%) and CC1 (4%) were also detected. The predominant spa type was t011 (n = 23), followed by t009 (n = 2), t034 (n = 1), t008 (n = 1), and t127 (n = 1). Conclusions: The results of this study extend the current body of knowledge on the population structure, resistance phenotypes, and virulence and resistance gene profiles of MRSA from livestock and companion animals.