Finger Necrotizing Fasciitis and Septicemia Caused by Vibrio vulnificus.

Background: Vibrio vulnificus infections develop rapidly and have high mortality and disability rates. Vibrio vulnificus can cause local wound infection, gastroenteritis, or septicemia. Case Presentation: In this case, an 86-year-old male was accidentally stabbed in the middle of his right thumb while cleaning whitewater fish and came to the emergency department with high fever and painful swelling of the right hand. Physical examination revealed hemorrhagic bullae in the right hand. Emergency surgery and bacterial culture were performed. Because of timely antibiotic use and surgical treatment, the patient eventually recovered and was discharged from the hospital. Conclusions: This case suggests that the possibility of Vibrio vulnificus should be considered in cases of severe infection of the extremities, even without a history of seafood consumption or seawater exposure. Early recognition, rational choice of antibiotic agents, and timely wound debridement can substantially improve the prognosis of patients and reduce mortality.

Microbial Community Changes in Silkworms Suspected of Septicemia and Identification of Serratia sp.

Diseases that occur in silkworms include soft rot, hardening disease, digestive diseases, and sepsis. However, research on the causes of bacterial diseases occurring in silkworms and the resulting changes in the microbial community is lacking. Therefore, we examined the morphological characteristics of sepsis and changes in the microbial community between silkworms that exhibit a unique odor and healthy silkworms; thus, we established a relationship between disease-causing microorganisms and sepsis. After producing a 16S rRNA amplicon library for samples showing sepsis, we obtained information on the microbial community present in silkworms using next-generation sequencing. Compared to that in healthy silkworms, in silkworms with sepsis, the abundance of the Firmicutes phylum was significantly reduced, while that of Proteobacteria was increased. Serratia sp. was dominant in silkworms with sepsis. After bacterial isolation, identification, and reinfection through the oral cavity, we confirmed this organism as the disease-causing agent; its mortality rate was 1.8 times higher than that caused by Serratia marcescens. In summary, we identified a new causative bacterium of silkworm sepsis through microbial community analysis and confirmed that the microbial community balance was disrupted by the aberrant proliferation of certain bacteria.

Redefining piscine lactococcosis.

Piscine lactococcosis is a significant threat to cultured and wild fish populations worldwide. The disease typically presents as a per-acute to acute hemorrhagic septicemia causing high morbidity and mortality, recalcitrant to antimicrobial treatment or management interventions. Historically, the disease was attributed to the gram-positive pathogen Lactococcus garvieae. However, recent work has revealed three distinct lactococcosis-causing bacteria (LCB)-L. garvieae, L. petauri, and L. formosensis-which are phenotypically and genetically similar, leading to widespread misidentification. An update on our understanding of lactococcosis and improved methods for identification are urgently needed. To this end, we used representative isolates from each of the three LCB species to compare currently available and recently developed molecular and phenotypic typing assays, including whole-genome sequencing (WGS), end-point and quantitative PCR (qPCR) assays, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), API 20 Strep and Biolog systems, fatty acid methyl ester analysis (FAME), and Sensititre antimicrobial profiling. Apart from WGS, sequencing of the gyrB gene was the only method capable of consistent and accurate identification to the species and strain level. A qPCR assay based on a putative glycosyltransferase gene was also able to distinguish L. petauri from L. garvieae/formosensis. Biochemical tests and MALDI-TOF MS showed some species-specific patterns in sugar and fatty acid metabolism or protein profiles but should be complemented by additional analyses. The LCB demonstrated overlap in host and geographic range, but there were relevant differences in host specificity, regional prevalence, and antimicrobial susceptibility impacting disease treatment and prevention. IMPORTANCE: Lactococcosis affects a broad range of host species, including fish from cold, temperate, and warm freshwater or marine environments, as well as several terrestrial animals, including humans. As such, lactococcosis is a disease of concern for animal and ecosystem health. The disease is endemic in European and Asian aquaculture but is rapidly encroaching on ecologically and economically important fish populations across the Americas. Piscine lactococcosis is difficult to manage, with issues of vaccine escape, ineffective antimicrobial treatment, and the development of carrier fish or biofilms leading to recurrent outbreaks. Our understanding of the disease is also widely outdated. The accepted etiologic agent of lactococcosis is Lactococcus garvieae. However, historical misidentification has masked contributions from two additional species, L. petauri and L. formosensis, which are indistinguishable from L. garvieae by common diagnostic methods. This work is the first comprehensive characterization of all three agents and provides direct recommendations for species-specific diagnosis and management.

Chromobacterium sp. septicemia in Sweden. A clinical case report.

BACKGROUND: Chromobacterium is a genus of fourteen species with validly published names, most often found in soil and waters in tropical and subtropical regions around the world. The most well-known species of the genus, C. violaceum, occasionally causes clinically relevant infections; cases of soft tissue infections with septicemia and fatal outcomes have been described. CASE PRESENTATION: Here, we present a clinical case report of a 79-year-old man from Sweden with a soft-tissue infection and septicemia. The pathogen was identified as a strain of Chromobacterium species, but not C. violaceum. The patient was treated with clindamycin and ciprofloxacin and recovered well. CONCLUSIONS: This case report demonstrates the potential of Chromobacterium species as infectious agents in immunocompetent patients. It also indicates the existence of a novel species.

[Urosepsis: pathophysiology, diagnosis, and management-an update]. / Urosepsis: Pathophysiologie, Diagnose und Management ­ ein Update.

Urinary tract infections vary widely in their clinical spectrum, ranging from uncomplicated cystitis to septic shock. Urosepsis accounts for 9-31% of all cases of septicemia and is often associated with nosocomial infections. A major risk factor for urosepsis is the presence of obstructive uropathy, caused by conditions such as urolithiasis, tumors, or strictures. The severity and course of urosepsis depend on both the virulence of the pathogen and the patient's specific immune response. Prompt therapy, including antimicrobial treatment and eradication of the infection source, along with supportive measures for circulatory and respiratory stabilization, and adjunctive therapies such as hemodialysis and glucocorticoid therapy, is crucial. Due to demographic changes, an increase in cases of urosepsis is expected-thus, it is of utmost importance for urologists to be familiar with targeted diagnostics and effective treatment.

Critical Illness Polyneuropathy in a Child: A Case Report.

Critical illness polyneuropathy (CIP) and myopathy (CIM) are underreported conditions in critically ill children with prolonged intensive care unit stays and mechanical ventilation. We report a case of a 10-year-old boy with pneumococcal meningoencephalitis with severe sepsis and multiorgan dysfunction. The child required prolonged ventilation, sedation, and inotropic support. He had repeated extubation failures and the development of quadriparesis with areflexia. Electrophysiology studies were consistent with CIP with acute motor and sensory axonal polyneuropathy and elevated muscle enzymes. He was treated with supportive measures and physiotherapy along with management of the underlying condition. He recovered slowly over 68 days with a good recovery with a modified Rankin's scale score of 4 on discharge. There is a need to pay attention to all critically ill children and should have a high index of suspicion for the development of CIP/CIM which can have an impact on course and outcome.

Relevance and antimicrobial resistance profile of Klebsiella pneumoniae in neonatal sepsis.

BACKGROUND: Newborns are particularly susceptible to infection in hospitals, with neonatal sepsis being the most common infection symptom and the third leading cause of neonatal death. Klebsiella pneumoniae is a gram-negative bacterium of Enterobacteriaceae, which is a common pathogen of neonatal septicemia. In this study, we will analyze and evaluate the current status, clinical characteristics, and drug resistance of Klebsiella pneumoniaesepsis infection in Neonatal Intensive Care Unit (NICU), with the aim of providing effective basis for timely and accurate clinical diagnosis and treatment in clinical practice. METHODS: Statistical analysis was performed on 75 cases of Enterobacteriaceae septicemia in infants admitted to NICU in a special obstetrics and gynecology hospital in Shanghai from January 2020 to June 2022. Based on bacterial identification, isolates were divided into the Klebsiella pneumoniae (KP) group (n = 49) and the non-KP Enterobacteriaceae group (n = 26). The infection, clinical characteristics, and bacterial resistance of the two groups of infected patients were compared. RESULTS: Comparing the clinical characteristics of the two groups, the results showed that most of the subjects in the KP and non-KP groups were premature infants, accounting for 100% and 92.3% of subjects, respectively; late onset was the main disease in both groups, accounting for 93.9% and 80.8% of subjects, respectively. All patients received Peripherally Inserted Central Catheter(PICC). The levels of pro calcitonin and CRP (C-reactive protein) were significantly higher in the KP group compared with those in the non-KP group (p < .05). At the same time, the incidence of thrombocytopenia in the KP group was significantly higher than that in the non-KP group (p < .05). The proportion of antimicrobial drug exposure in the KP group is higher than that in the non-KP group. The drug resistance of the KP group to ceftazidime, ceftriaxone, cefepime, ampicillin/sulbactam, aztreonam, ciprofloxacin and compound sulfamethoxazole was significantly higher than that of the non-KP group, whereas the drug resistance rate to cefotetan, gentamycin and to bramycin was significantly lower than that of the non-KP group, Statistically significant differences (p < .05). 38 cases of Klebsiella pneumoniae producing ESBLs were tested for related resistance genes. The results showed that the main resistance types were SHV and TEM, with detection rates of 60.6% and 28.9%. CONCLUSIONS: This study shows that neonatal sepsis caused by Klebsiella pneumoniae infection has a high incidence and drug resistance in premature and low birth weight infants, and has become a serious public health problem; Clinicians should pay attention to differential diagnosis, Reasonable selection of antibiotics to reduce the generation of drug-resistant bacteria.

Septicemic salmonellosis in suckling piglets resulting from improper intramuscular administration of an oral vaccine.

We describe an unusual outbreak of mortality in suckling piglets following the misadministration of an oral vaccine against Salmonella Typhimurium and Salmonella Choleraesuis. Within 3-48 h of vaccination of a batch of ~700 piglets, ~300 developed marked swelling in the dorsal neck region, respiratory distress, fever, recumbency, and apathy. In total, ~100 died, and 4 were submitted for autopsy. Gross and microscopic lesions consisted of focally extensive areas of purple discoloration in the skin of the cervical region, associated with edema and hemorrhage in the subcutis and muscles. Additionally, there was interstitial pneumonia with marked interlobular edema and mild fibrinous pleuritis. Aerobic bacterial culture identified Salmonella Typhimurium (3 cases) and Salmonella Choleraesuis (1 case) in samples of skeletal muscle and lung and from pleural swab samples. Marked immunostaining against Salmonella spp. was observed in the skeletal muscle of the cervical region, as well as in blood vessels and macrophages from the lung, liver, spleen, and kidney. We concluded that inappropriate intramuscular administration of an oral vaccine against Salmonella resulted in septicemia and death in a batch of piglets.

A Case Report of Whitmore's Disease: A True Masquerader.

Melioidosis is an uncommon bacterial infection that is endemic to countries like Southeast Asia and Northern Australia but less common in temperate zones than when seen in returned travelers. This disease can affect almost every organ, with the lung being the most common organ to be involved. Here, we present a 21-year-old diabetic male who came with complaints of fever, nonproductive cough, and sore throat with grade III-IV shortness of breath. Laboratory investigations revealed hypokalemia and isolates of Burkholderia pseudomallei on blood culture and sensitivity. High-resolution computed tomography (HRCT) of the chest showed widespread, variable-sized nodules with central cavitations diffusely scattered in bilateral lungs.

High-mortality epizootic Mycobacterium ulcerans ecovar Liflandii in a colony of Zaire Dwarf Clawed Frogs (Hymenochirus boettgeri).

Mycobacterium ulcerans ecovar Liflandii (MuLiflandii) was identified as the causative agent of mycobacteriosis in a research colony of Zaire dwarf clawed frogs (Hymenochirus boettgeri) at the University of Michigan. Clinical presentation included lethargy, generalized septicemia, cutaneous granulomas, coelomic effusion, and acute mortality. Identification of the mycobacterial species was based on molecular, microbiological, and histopathologic characteristics. These findings indicate that MuLiflandii is a primary cause of morbidity and mortality in Zaire dwarf clawed frogs and should be considered in the differential diagnosis of sepsis and coelomic effusion in amphibians. Mycobacterial speciation is important given the variability in pathogenesis within the family Mycobacteriaceae and the implications for both animal and human health as potential zoonoses. The Zaire dwarf clawed frog is a species common in the pet trade, and these findings provide consideration for this pathogen as a potentially important public health concern. This is the first report of MuLiflandii infection in the genus Hymenochirus and illustrates the diagnostic challenges of differentiating among both mycolactone-producing mycobacteria and Mycobacterium marinum. Furthermore, we demonstrate the utility of environmental sampling for this pathogen within the tank system, suggesting this mode of sampling could replace the need for direct frog surveillance.

Erysipelas with preferential brain and skin involvement in a Mediterranean bottlenose dolphin Tursiops truncatus.

Infections by Erysipelothrix rhusiopathiae occur in domestic animals and cause the disease known as 'erysipelas'. The ubiquity of Erysipelothrix spp. makes infection possible in a wide range of vertebrates and invertebrates. Cetaceans are highly susceptible to erysipelas, especially those under human care. The number of cases documented in wild cetaceans is low, the pathogenesis is incompletely understood, and the full spectrum of lesions is not well defined. The possible serotypes and species of the genus that can cause disease are unknown. In October 2022, a common bottlenose dolphin Tursiops truncatus stranded in Vilassar de Mar (Catalonia) showing skin lesions consistent with 'diamond skin disease', a characteristic lesion of erysipelas shared by swine and cetaceans. Necropsy was performed following standardized procedures, and multiple samples were taken for histopathology and bacteriology. Erysipelothrix sp. grew in pure culture in many tissue samples. Genetic characterization by multi-locus sequence analysis identified the species as E. rhusiopathiae. Histologically, the main lesions were an intense suppurative vasculitis of leptomeningeal arteries and veins with abundant intramural Gram-positive bacilli and meningeal hemorrhages. Meningeal lesions were considered the cause of death. The affected skin showed moderate suppurative dermatitis. Herein we document a case of erysipelas in a Mediterranean common bottlenose dolphin with unusual lesions in the leptomeningeal vessels and marked skin tropism. To our knowledge, this is the first case of severe brain involvement in erysipelas in a cetacean. We also provide a review of available cases in wild cetaceans, to highlight the characteristics of the disease and improve future diagnosis.

Ventricular mural thrombi - An occult occurrence?

Background: Ventricular mural thrombi are rare occurrences and form one of the common mechanical complications of myocardial infarctions. They also occur in patients with nonischemic myocardial disorders and even in those devoid of cardiac diseases. Clinical detection often depends on the size of the thrombi. Aim: This study was aimed at ascertaining the etiopathogenesis of mural thrombi with a clinicopathologic correlation. Materials and Methods: This was a 12-year retrospective observational study reviewing the autopsy records of all cases showing ventricular mural thrombi. The location, size, morphology, and histologic appearances of the thrombi were noted. The cases, depending on the etiology, were categorized into myocardial ischemic (Group 1), myocardial nonischemic (Group 2), and non-myocardial (Group 3) causes. These features were correlated with the clinical settings. Results: There were 93 cases of mural thrombi with an almost equal sex distribution and a mean age of 45.9 years. The cause was ischemic heart disease in most of the patients (Group 1, 46.2%), while 21.5% and 32.3% of patients belonged to Group 2 and Group 3, respectively. Unlike the large and dominantly left ventricular thrombi seen in Group 1, the other two groups frequently had biventricular involvement, location in the intertrabecular spaces, and a high microscopic detection. Clinical diagnosis had been made in only 3.2% of patients. Thromboembolism was noted in other organs in 34.4% of the total cases. Conclusion: Ventricular thrombi should be ruled out in patients with evidence of systemic and/or pulmonary thromboembolism, even in those without any cardiac disorders.

Meningoencephalitis caused by Non-O1, non-O139 Vibrio cholerae in an infant from southern Spain.

Non-O1, non-O139 Vibrio cholerae (NOVC) is an emergent pathogen that mainly causes gastroenteritis. Also, it causes ear, wound infections, and bacteremia but the nervous system is rarely affected. We report on a case of NOVC meningoencephalitis in an infant that recovered after antimicrobial therapy but later presented neurologic sequelae.

Predictors of Comorbidity of Malaria and Septicemia in Children Living in Malaria-Endemic Communities in Nigeria.

PURPOSE: The study attempted to identify possible overlap between serum cell-reactive proteins (C-rp) and hematological indices as predictors of comorbidity of malaria and septicemia among children attending primary healthcare facilities in Ilorin, Nigeria. METHODS: One hundred and ninety-three children (aged: ≤ 1-15 years) presenting with symptoms suggestive of malaria were enrolled. Blood specimens were collected and screened for: Romanowsky, culture, serum C-RP and hematological indices. RESULTS: One hundred and fifteen (59.6%) children had Plasmodium falciparum infections (female 69.0% and male 34.1%). Septicemia was common among 52 (26.9%), but malaria and septicemia co-infection was 42 (36.5%). C-rp levels were low (< 10 mg/L) in 41 (35.7%, OR 4.594, CI 2.463-8.571) and high (> 10 mg/L) in 74 (64.3%, OR 2.519, CI 1.681-3.775) among the malaria positives (p < 0.05). Children with low C-rp, 8 (15.4%, OR 9.413, CI 4.116-21.531) were positive for septicemia and high C-RP 44 (84.6%, OR 1.694, CI 1.396-2.055), but without malaria, respectively. Similarly, increased C-rp levels were significantly associated with clinical malaria; > 10,000 parasites/µL (OR 1.486, CI 1.076-2.054, P < 0.001). Malaria-positive versus negative showed that PCV, C-rp, hemoglobin, platelet, WBC, and neutrophil were statistically significant (P < 0.05). Two bacteria species were identified, viz; Staphylococcus aureus 39 (54.9%) and Escherichia coli 32 (45.1%). The trade-off between sensitivity and specificity occurred at 16.475 cut-off using C-rp and degree of malaria severity as the standard for AUROC. CONCLUSION: C-rp are inflammatory markers, though non-specificity may be associated with malaria prognosis and severity during malaria-septicemia co-infection.

A Comprehensive Review of the Common Bacterial Infections in Dairy Calves and Advanced Strategies for Health Management.

Dairy farming faces a significant challenge of bacterial infections in dairy calves, which can have detrimental effects on their health and productivity. This review offers a comprehensive overview of the most prevalent bacterial infections in dairy calves, including Escherichia coli, Salmonella typhimurium, Salmonella dublin, Salmonella enterica, Clostridium perfringens, Pasteurella multocida, Listeria monocytogenes, Mycoplasma bovis, and Haemophilus somnus. These pathogens can cause various clinical signs and symptoms, leading to diarrhea, respiratory distress, septicemia, and even mortality. Factors such as management practices, environmental conditions, and herd health influence the incidence and severity of the infections. Efficient management and prevention strategies include good colostrum and nutrient feeding, early detection, appropriate treatment, hygiene practices, and supportive care. Regular health monitoring and diagnostic tests facilitate early detection and intervention. The use of antibiotics should be judicious to prevent antimicrobial resistance and supportive care such as fluid therapy and nutritional support promotes recovery. Diagnostic methods, including immunological tests, culture, polymerase chain reaction (PCR), and serology, aid in the identification of specific pathogens. This review also explores recent advancements in the diagnosis, treatment, and prevention of bacterial infections in dairy calves, providing valuable insights for dairy farmers, veterinarians, and researchers. By synthesizing pertinent scientific literature, this review contributes to the development of effective strategies aimed at mitigating the impact of bacterial infections on the health, welfare, and productivity of young calves. Moreover, more research is required to enhance the understanding of the epidemiology and characterization of bacterial infections in dairy calves.

Feedback loop regulation between viperin and viral hemorrhagic septicemia virus through competing protein degradation pathways.

Viperin is an antiviral protein that exhibits a remarkably broad spectrum of antiviral activity. Viperin-like proteins are found all kingdoms of life, suggesting it is an ancient component of the innate immune system. However, viruses have developed strategies to counteract viperin's effects. Here, we describe a feedback loop between viperin and viral hemorrhagic septicemia virus (VHSV), a common fish pathogen. We show that Lateolabrax japonicus viperin (Ljviperin) is induced by both IFN-independent and IFN-dependent pathways, with the C-terminal domain of Ljviperin being important for its anti-VHSV activity. Ljviperin exerts an antiviral effect by binding both the nucleoprotein (N) and phosphoprotein (P) of VHSV and induces their degradation through the autophagy pathway, which is an evolutionarily conserved antiviral mechanism. However, counteracting viperin's activity, N protein targets and degrades transcription factors that up-regulate Ljviperin expression, interferon regulatory factor (IRF) 1 and IRF9, through ubiquitin-proteasome pathway. Together, our results reveal a previously unknown feedback loop between viperin and virus, providing potential therapeutic targets for VHSV prevention. Importance: Viral hemorrhagic septicaemia (VHS) is a contagious disease caused by the viral hemorrhagic septicaemia virus (VHSV), which poses a threat to over 80 species of marine and freshwater fish. Currently, there are no effective treatments available for this disease. Understanding the mechanisms of VHSV-host interaction is crucial for preventing viral infections. Here, we found that, as an ancient antiviral protein, viperin degrades the N and P proteins of VHSV through the autophagy pathway. Additionally, the N protein also impacts the biological functions of IRF1 and IRF9 through the ubiquitin-proteasome pathway, leading to the suppression of viperin expression. Therefore, the N protein may serve as a potential virulence factor for the development of VHSV vaccines and screening of antiviral drugs. Our research will serve as a valuable reference for the development of strategies to prevent VHSV infections.

The Assessment of Infection Risk in Patients with Vitiligo Undergoing Dialysis for End-Stage Renal Disease: A Retrospective Cohort Study.

Vitiligo is an autoimmune condition that causes patchy skin depigmentation. Although the mechanism by which vitiligo induces immunocompromise is unclear, other related autoimmune diseases are known to predispose those affected to infection. Individuals with vitiligo exhibit epidermal barrier disruption, which could potentially increase their susceptibility to systemic infections; patients with renal disease also show a predisposition to infection. Nevertheless, there is little research addressing the risk of infection in dialysis patients with vitiligo in comparison to those without it. A retrospective analysis was performed on patients with end-stage renal disease (ESRD) in the United States Renal Data System who started dialysis between 2004 and 2019 to determine if ESRD patients with vitiligo are at an increased risk of bacteremia, cellulitis, conjunctivitis, herpes zoster, or septicemia. Multivariable logistic regression modeling indicated that female sex, black compared to white race, Hispanic ethnicity, hepatitis C infection, and tobacco use were associated with an enhanced risk of vitiligo, whereas increasing age and catheter, versus arteriovenous fistula, and access type were associated with a decreased risk. After controlling for demographics and clinical covariates, vitiligo was found to be significantly associated with an increased risk of bacteremia, cellulitis, and herpes zoster but not with conjunctivitis and septicemia.

Horse to human: Streptococcus equi septicemia presenting as endogenous endophthalmitis.

Purpose: To present a rarely reported systemic infection with streptococcus equi subspecies zooepidemicus (streptococcus equi), transmitted from a horse, and to describe successful treatment when complicated by endogenous endophthalmitis. Observations: We diagnosed suspected streptococcus equi septicemia presenting as loss of vision in the right eye of an otherwise healthy polo player/horse trainer. He received immediate intravenous antibiotics and three vitrectomies with two intravitreal antibiotic injections during the first week, to cure infection and subsequent retinal detachment. Blood and initial vitreous cultures rapidly grew streptococcus equi. The septicemia was quickly controlled by systemic antibiotics without developing commonly seen and often fatal meningitis. The right eye recovered 20/30 visual acuity three months post infection. Conclusions: Presentation of this rare septicemia as endogenous endophthalmitis illustrates the potentially lifesaving role of early diagnosis by the ophthalmologist. Immediate and recurrent vitrectomy in conjunction with intravitreal and systemic antibiotic therapy resulted in recovery of near normal vision, whereas less timely and interventional treatments have failed heretofore.

Susceptibility of the cultured Amazonian fish, Colossoma macropomum, to experimental infection with Aeromonas species from ornamental fish.

The global ornamental fish trade carries important risk factors for spreading pathogens between different countries and regions, not only for ornamental fish but also for cultured fish and even other animal species. In the current study, we reported the capacity of Aeromonas veronii and A. hydrophila isolated from ornamental fish to experimentally infect the reared Amazonian fish Colossoma macropomum. For this, those bacteria were identified, and a primary characterization was performed. Fish were inoculated with 0.1 mL of increasing concentrations of A. hydrophila or A. veronii (C1 = 1 × 102; C2 = 1.8 × 104; C3 = 2.1 × 106; C4 = 2.4 × 108 bacterial cells per mL) in the coelomic cavity. In the control group, fish received the same volume of sterile saline solution (0.9 %). Fish presented petechiae, skin suffusions, and mortality rates up to 100 % according to the inoculum concentration. Histopathologically, fish presented necrosis with karyolysis, loss of the cytoplasmic delimitation of cells of the renal tubules and hepatocytes, hemorrhage, cellular edema, and the presence of bacterial cells. The LD50-96h of A. veronii on C. macropomum was estimated at 2.4 × 106 CFU mL-1 and of A. hydrophila at 1.408 × 105 CFU mL-1. The results demonstrated that it is possible that Aeromonas species isolated from ornamental fish affect C. macropomum, causing similar clinical signs and lesions. This shows the importance of promoting risk control measures worldwide regarding the trade of ornamental fish.

The role of Aeromonas genotyping in virulence for Dicentrarchus labrax.

Aeromonas septicemia still represents a serious challenge facing the global aquaculture sector. In the present study, Aeromonas caviae and A. veronii were isolated from four diseased European seabass (Dicentrarchus labrax) farms experiencing a high mortality rate. Diseased fish showed haemorrhages on the external body surface with exophthalmia, cataracts, scale desquamation, skin ulcers and fin erosions. The most common post-mortem findings were congested internal organs, particularly the liver and posterior kidney. Twenty-eight A. Veronii and 11 A. caviae isolates were identified biochemically by the Vitek 2 system and then confirmed by PCR and phylogenetic analysis. Hemolysin (hlyA) and aerolysin (aer) were the most abundant virulence genes in the recovered isolates, followed by cytotoxic enterotoxin (act) and heat-stable enterotoxin (ast). A. caviae was more virulent than A. veronii for D. labrax fingerlings as LD50 ranging between (>1 × 108 -6.2 × 107 ) for A. veronii and (2.9 × 107 -8.3 × 107 ) for A. caviae. The sensitivity test indicated the effectiveness of norfloxacin, doxycycline and oxytetracycline against the tested isolates. Serum cortisol significantly increased in the infected groups, while catalase and glutathione peroxidase activities significantly decreased at 2 days post-infection (DPI) and then increased at 6 DPI. The presence of virulence genes was associated with bacterial pathogenicity expressed in fish mortality rate. Virulence genes also drastically affect cortisol levels more than catalase and glutathione peroxidase levels.