• Journal of Microbiology and Biotechnology
• /
• v.15 no.6
• /
• pp.1197-1206
• /
• 2005

Vibrio vulnificus is an opportunistic pathogen that causes a septicemia and expresses numerous virulence factors, in which luxS and smcR are genes encoding for components responsible for quorum-sensing regulation. In the present study, null mutants were constructed with lesions in each or both of these two genes from the V. vulnificus Vv$\Delta$Z strain, which is a lacZ$^{-}$ and chloramphenicol/streptomycin-resistant derivative of the wild-type ATCC29307 strain, and their phenotypes related to virulence were compared with those of the parental cells. $LD_{50}$ and histopathological findings of luxS-, smcR-, or luxS- smcR- deficient mutant were not different from those of the parent strain, a lacZ-deficient streptomycin-resistant strain in mice. However, time of death in mice was delayed, and numbers of bacteria survived in bloodstream after intraperitoneal injection in mice were decreased by mutation, especially luxS and smcR double mutant (VvSR$\Delta$ZSR). These phenomena were supported by increased serum sensitivity and delayed bacterial proliferation in both murine blood and iron-restricted medium. These results suggest that the luxS and luxR homologous genes in V. vulnificus could playa role in bacterial survival in host by enhancing proliferation and adjusting to changed environment.

• Pediatric Infection and Vaccine
• /
• v.19 no.3
• /
• pp.89-110
• /
• 2012

Meningococcal Disease, manifesting as meningitis and septicemia, is a life-threatening bacterial infection that results in significant morbidity and mortality, particularly in childhood. Its epidemic potential and limited opportunities for clinical intervention due to its rapid course present unique public health and clinical challenges. Incidence is highest in infants and young children, with a secondary peak of risk in adolescents. Approximately 10% of cases are fatal and survivors can be left with serious and permanent sequelae including amputations, hearing loss and cognitive impairment. Transmission is only from human-to-human, by infected respiratory tract secretions or saliva and therefore crowding poses a tremendously elevated risk for disease development. Military recruits and university students are at high risk due to the high carriage rate in adolescents, their behavior patterns and close contact. Menveo$^{(R)}$ (Novartis Vaccines and Diagnostics), a novel quadrivalent meningococcal conjugate vaccine directed against meningococcal serogroups A, C, W-135 and Y, has been shown to be immunogenic and well tolerated in all age groups and was recently licensed for use in Korea. Recent cases and deaths among military recruits drew public attention to their elevated risk and the Korean government has recommended vaccination of all new military recruits. Many Korean students seek to attend school, university, or language institutes in countries where routine meningococcal vaccination is required - clinicians should be aware of such requirements to ensure that students are vaccinated prior to arrival in the destination country.

• Microbiology and Biotechnology Letters
• /
• v.27 no.1
• /
• pp.70-74
• /
• 1999

Vibrio vulnificus, a normal bacterial inhabitant of estuaries, is of concern because it can be a potent human pathogen, a causing septicemia, wound infections and gastrointestinal disease in susceptible host. In this survey, total 431 samples were obtained from different sites of the Chonman coastal area during the periods from Mar. 1997 to Feb. 1998. Vibrio vulnificus was isolated from the middle of May to the begining of November of 1997 in Chonman coastal area, as the seawater temperature was at 20$^{\circ}C$ and 15$^{\circ}C$, respectively and was rapidly increased to above 40% from July to September. The isolation rates of V. vulnificus from sediment, seawater, raw seafoods and aquarium water were 52.1%, 49.1%, 32.5%, and 27.3%, respectively and isolation rate was highest in oyster among various collected samples. V.vulnificus was also isolated from 73.1%(38/52) of sampling sites of Chonman coastal area.

• Journal of Microbiology
• /
• v.39 no.3
• /
• pp.213-218
• /
• 2001

The treatment of Patients with bacteraemia and septicemia requires accurate and rapid identification of the pathogen so that the physician can be guided regarding the selection of the proper antimicrobial therapy. The usual procedure is to withdraw an aliquot of the positive blood culture sample for gram staining and subculturing on the media for the growth and subsequent identification, and susceptibility determinations. It was noticed that during the process some microbiologists would sniff the effluent gases that are products of metabolism and in some cases guess the identity of the bacterium. That Prompted us to engage in systematic investigation of two gram positive and two gram negative bacteria using an electronic nose that had been proven successful in distinguishing the aroma of coffee beans from different sources. The investigation was successful in illustrating the efficacy of such a device in this clinical setting to distinguish Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. A representative set of patterns obtained with this apparatus is displayed as well. A representative set of patterns obtained with this apparatus is displayed as well. No effort was made to determine an optimal set of sensors for some specific set of bacterial metabolism gaseous products.

• Pediatric Infection and Vaccine
• /
• v.26 no.3
• /
• pp.188-193
• /
• 2019

Since the implementation of conjugate Haemophilus influenzae serotype b (Hib) vaccine, the rate of infections caused by Hib has dramatically decreased, and the proportion of infections caused by non-type b H. influenzae has increased. Cerebral venous sinus thrombosis (CVST) is rare; however, it should be considered as a potential complication of bacterial meningitis. Herein, we report about a child who developed CVST after being diagnosed with H. influenzae serotype f meningitis.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.5
• /
• pp.595-598
• /
• 2000

Aeromonas hydrophila is a pathogen to fish as well as human. It is a food-borne disease, and causes severe mortality in fish, and sometimes severe septicemia in human. In this study, a rapid detection method using latex agglutination has been developed for A. hydrophila. Polyclonal antibodies were raised against membrane and whole cells of three isolates from rainbow trout. Among these, latex particles coated with antibodies raised against whole cells of isolate No. 2 showed the best sensitivity. With latex particles coated with this antibody, we could detect $5{\times}10^4$ CFU of A. hydrophila in 5 min. The cross-reactivity with bacteria constituting the normal intestinal microflora and other pathogens for rainbow trout was insignificant. This latex agglutination assay method produced positive reaction with all clinical isolates of A. hydrophila which were identified by species-specific PCR for 16S rRNA in A. hydrophila.

• Pediatric Infection and Vaccine
• /
• v.25 no.2
• /
• pp.82-90
• /
• 2018

Purpose: Survival after liver transplantation (LT) has improved over the years, but infection is still a major complication. We aimed to identify the characteristics of bacterial infections in pediatric LT recipients. Methods: This study is a retrospective review of 189 consecutive children undergoing LT between 2000 and 2015 at a single center. In this study, the incidence of infection was determined for the following periods: within 1 month, between 1-5 months, and between 6-12 months. Patients who underwent liver transplants more than once or multiple organ transplants were excluded. Results: All patients had received postoperative antibiotic for 3 days. Only the maintenance immunosuppression with oral tacrolimus and steroids were performed. As a result, 132 bacterial infections developed in 87 (46.0%) patients (0.70 events per person-year). Bacterial infections occurred most frequently within the first month (n=84, 63.6%) after LT. In the pathogens, Staphylococcus aureus (15.2%), Enterococcus species (15.2%), and Klebsiella species (13.6%) were most common. Regarding the organ infected, bloodstream was most common (n=39, 29.5%), followed by peritoneum (n=28, 21.2%), urinary tract (n=25, 18.9%), and lungs (n=20, 15.2%). We changed prophylactic antibiotics from ampicillin-sulbactam to piperacillin-tazobactam at 2011, October, there were no significant effects in the prevalence of antibiotics resistant bacterial infections. The 1-year mortality was 9.0% (n=17), in which 41.2% (n=7) was attributable to bacterial infection; septicemia (n=4), pneumonia (n=2), and peritonitis (n=1). Conclusions: The incidence and type of bacterial infectious complications after LT in pediatric patients were similar to those of previous studies. Bacterial complications affecting mortality occur within 6 months after transplantation, so proper prophylaxis and treatment in this period may improve the prognosis of LT.

• Journal of fish pathology
• /
• v.30 no.2
• /
• pp.135-148
• /
• 2017

Pathogen introductions associated with aquatic invasive species threaten ecosystems and biodiversity worldwide. Bigheaded carps (BHC), including Silver Carp Hypophthalmichthys molitrix, Bighead Carp H. nobilis, and their hybrids, are prolific, invasive pests in central US rivers. However, little is known about pathogen effects on invading BHC or how BHC affect the disease risk profile for native fishes in receiving ecosystems. We therefore conducted, from May 2013-December 2014, a systematic pathogen survey for BHC and native fishes in the Wabash River watershed, Indiana, USA. We found Pseudomonas fluorescens, P. putida, and Salmonella enterica DNA in BHC as well as native fishes, although none of these bacteria were exclusively present in BHC. DNA from other bacterial taxa was detected only in native fishes and Common Carp Cyprinus carpio. No gastrointestinal helminths were detected in BHC, although they were common in most native fishes examined. We also conducted in vitro studies on BHC tissues (skin, gill, fin, and fry) and found high sensitivity to Largemouth Bass virus, viral hemorrhagic septicemia virus, and infectious pancreatic necrosis virus. We conclude that BHC are not heavily burdened by bacteria, viruses and parasites in the invaded study ecosystems, although they do harbor native bacteria and show potential for high sensitivity to endemic viruses.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2002.10a
• /
• pp.59-62
• /
• 2002

The role of a TolC homologue in the virulence of Vibrio vulnificus, a marine bacterium causing serious wound infection and fulminant septicemia in persons with underlying conditions, has been studied. TolC, an outer membrane protein, has been implicated in a variety of bacterial functions including export of diverse molecules ranging from large proteins to antibiotics. A homologue of the tolC gene of V. cholerae, which has been shown to be required for bile resistance, cytotoxicity and colonization of this organism, was identified in the partially determined genome sequence of V. vulnificus. To determine the role of TolC in the virulence of V. vulnificus, a TolC-deficient (TD) mutant was isolated by in vivo allelic exchange. Compared with the parent strain, the TD mutant was more sensitive to bile, and much less virulent in mice challenged subcutaneously. This mutant was noncytotoxic to the HEp-2 cells, but its metalloprotease and cytolysin activities in the culture supernatant were comparable to the parent strain. In addition, the resistance of the TD mutant to human serum bactericidal activity as well as its growth in either human or murine blood was not affected. Collectively, our data suggest that TolC may be involved in colonization and/or spread of V. vulnificus to the blood stream, probably by secreting a cytotoxin other than the cytolysin.

• Journal of fish pathology
• /
• v.35 no.1
• /
• pp.77-92
• /
• 2022

Aquaculture development is based on the ideas of increasing production while reducing economic losses. Bacterial diseases are the leading source of fish cases. Citrobacter freundii has been linked to septicemia and mortality all over the world. In the current study, the cause of mortality in O. niloticus was C. freundii MW279218. External hemorrhages were seen on the affected fish, as well as paleness in the liver and kidney congestion. C. freundii MW279218 had a median lethal dosage of 1.5×10⁵ CFU/mL. Zinc oxide and zinc oxide nanoparticles (ZnO-NPs) were tested for their biocidal effectiveness against C. freundii MW279218. The lethal effect of ZnO-NPs for C. freundii MW279218 was 100% when compared to zinc oxide compound, and the inhibition zone width was 2.31.1mm at the highest tested concentrations (70 mg/L) compared to the lowest (35 and 45 mg/L, respectively). Fish were fed three different diets for 28 days: diet 1 (no additives), diet 2 (100 mg of ZnO-NPs/kg of feed), and diet 3 (200 mg of ZnO-NPs/kg of feed). Organs were also collected for histopathology 96 hours after injection (P<0.05). In the groups given 200 mg of ZnO-NPs, there was 10% mortality and 80% RPS. The group fed 100 mg of ZnO-NPs/kg, on the other hand, had 20% mortality and 60% RPS, compared to 50% mortality in the control positive group. Histopathological examinations demonstrated significant alterations in the control positive group and mild lesions in the hepatopancreas of the groups administered 100 mg ZnO-NPs/kg of feed. The groups fed 200 mg of ZnO-NPs/kg diet, on the other hand, showed no histological alterations. ZnO-NPs were found to be effective in the up regulation of both IL-10 and complement 5 immune-related genes.