Skin Antisepsis before Surgical Fixation of Extremity Fractures.

BACKGROUND: Studies evaluating surgical-site infection have had conflicting results with respect to the use of alcohol solutions containing iodine povacrylex or chlorhexidine gluconate as skin antisepsis before surgery to repair a fractured limb (i.e., an extremity fracture). METHODS: In a cluster-randomized, crossover trial at 25 hospitals in the United States and Canada, we randomly assigned hospitals to use a solution of 0.7% iodine povacrylex in 74% isopropyl alcohol (iodine group) or 2% chlorhexidine gluconate in 70% isopropyl alcohol (chlorhexidine group) as preoperative antisepsis for surgical procedures to repair extremity fractures. Every 2 months, the hospitals alternated interventions. Separate populations of patients with either open or closed fractures were enrolled and included in the analysis. The primary outcome was surgical-site infection, which included superficial incisional infection within 30 days or deep incisional or organ-space infection within 90 days. The secondary outcome was unplanned reoperation for fracture-healing complications. RESULTS: A total of 6785 patients with a closed fracture and 1700 patients with an open fracture were included in the trial. In the closed-fracture population, surgical-site infection occurred in 77 patients (2.4%) in the iodine group and in 108 patients (3.3%) in the chlorhexidine group (odds ratio, 0.74; 95% confidence interval [CI], 0.55 to 1.00; P = 0.049). In the open-fracture population, surgical-site infection occurred in 54 patients (6.5%) in the iodine group and in 60 patients (7.3%) in the chlorhexidine group (odd ratio, 0.86; 95% CI, 0.58 to 1.27; P = 0.45). The frequencies of unplanned reoperation, 1-year outcomes, and serious adverse events were similar in the two groups. CONCLUSIONS: Among patients with closed extremity fractures, skin antisepsis with iodine povacrylex in alcohol resulted in fewer surgical-site infections than antisepsis with chlorhexidine gluconate in alcohol. In patients with open fractures, the results were similar in the two groups. (Funded by the Patient-Centered Outcomes Research Institute and the Canadian Institutes of Health Research; PREPARE ClinicalTrials.gov number, NCT03523962.).

[Acute haematogenous osteomyelitis of the pelvis with multifocal pyogenic abscesses in an adult]. / Ostryi gematogennyi osteomielit taza u vzroslogo s mnozhestvennymi gnoinymi metastazami.

Acute hematogenous osteomyelitis (AHO) in adults is a rare disease complicating timely diagnosis. Even greater difficulties are observed in case of pelvic bone lesion. The authors report AHO of the pelvis an adult. Osteomyelitis was complicated by generalized infection and multiple pyogenic abscesses in subcutaneous adipose tissue of the upper and lower extremities. Detection of primary infectious focus was complicated by extreme severity of the patient's condition and low informative value of X-ray and ultrasound at the early stage of disease. Staphylococcus aureus was obtained from blood culture and infectious foci. Surgical debridement along with complex intensive care ensured a positive outcome.

Umbilicated papules on the bilateral upper and lower extremities.

Cryptococcosis is a rare opportunistic infection with morphologically diverse cutaneous presentations. Primary infection typically occurs in the lungs with subsequent hematogenous dissemination to other organ systems, especially in immunocompromised patients. Herein, we report a woman in her 70's who presented with pruritic, umbilicated papulonodules of the bilateral upper and lower extremities present for many weeks. She was diagnosed with disseminated Cryptococcus and subsequently evaluated for potential pulmonary and meningeal disease involvement. She died as a result of multiple medical comorbidities.

Independent Predictors of Mortality for Aeromonas Necrotizing Fasciitis of Limbs: An 18-year Retrospective Study.

Necrotizing fasciitis (NF) of the limbs caused by Aeromonas species is an extremely rare and life-threatening skin and soft tissue infection. The purpose of this study was to evaluate the specific characteristics and the independent predictors of mortality in patients with Aeromonas NF. Sixty-eight patients were retrospectively reviewed over an 18-year period. Differences in mortality, demographics data, comorbidities, symptoms and signs, laboratory findings, microbiological analysis, empiric antibiotics treatment and clinical outcomes were compared between the non-survival and the survival groups. Twenty patients died with the mortality rate of 29.4%. The non-survival group revealed significant differences in bacteremia, monomicrobial infection, cephalosporins resistance, initial ineffective empiric antibiotics usage, chronic kidney disease, chronic hepatic dysfunction, tachypnea, shock, hemorrhagic bullae, skin necrosis, leukopenia, band polymorphonuclear neutrophils >10%, anemia, and thrombocytopenia. The multivariate analysis identified four variables predicting mortality: bloodstream infection, shock, skin necrosis, and initial ineffective empirical antimicrobial usage against Aeromonas. NF caused by Aeromonas spp. revealed high mortality rates, even through aggressive surgical debridement and antibacterial therapies. Identifying those independent predictors, such as bacteremia, shock, progressive skin necrosis, monomicrobial infection, and application of the effective antimicrobial agents against Aeromonas under the supervision of infectious doctors, may improve clinical outcomes.

Clinical features, microbiological epidemiology and recommendations for management of cellulitis in extremity lymphedema.

BACKGROUND: This high volume, single center study investigated the prevalence, bacterial epidemiology, and responsiveness to antibiotic therapy of cellulitis in extremity lymphedema. METHODS: From 2003 to 2018, cellulitis events from a cohort of 420 patients with extremity lymphedema were reviewed. Demographics, lymphedema grading, symptoms, inflammatory markers, cultures and antibiotic therapy regimens were compiled from cellulitis episodes data. Univariate and multivariate analyses were performed for detailed analysis. RESULTS: A total of 131 separate episodes of cellulitis were recorded from 43 (81.1%) lower limb and 10 (19.9%) upper limb lymphedema patients. The prevalence and recurrence rates for cellulitis in lymphedema patients were 12.6% (53 of 420) and 56.6% (30 of 53), respectively. The most common findings were increased limb circumference (127 of 131; 96.9%) and abnormal C-reactive protein (CRP) level (86 of 113; 76.1%). Blood cultures were obtained in 79 (60.3%) incidents, with 9 (11.4%) returning positive. Streptococcus agalactiae was the most isolated bacterium (5 of 9; 55.5%). CONCLUSIONS: The cellulitis prevalence and recurrence rate in extremity lymphedema were 12.6%, and 56.6%, respectively. Strongest indicators of cellulitis were increased affected limb circumference and elevated CRP level. Empiric antibiotic therapy began with coverage for Steptococcus species before broadening to anti-Methicillin-resistant Staphylococcus aureus and anti-Gram negatives if needed for effective treatment of extremity lymphedema cellulitis.

Risk factors associated with recurrence of extremity osteomyelitis treated with the induced membrane technique.

INTRODUCTION: Our aim was to observe the efficacy of the induced membrane technique in the treatment of extremity osteomyelitis and to analyse the causes of infection recurrence and its risk factors. METHODS: We retrospectively analysed 424 cases of extremity osteomyelitis treated with the induced membrane technique in our department between May 2013 and June 2017. Infection recurrence time, recurrence sites and other relevant information were collected, summarized, and analysed. RESULTS: A total of 424 patients were considered as "cured" of osteomyelitis after the first stage and the induced membrane technique was performed to rebuild the bone defects. After a mean follow-up of 31.6 (16-63) months, 52 patients had recurrence of infection, including 42 tibias and 10 femurs. The recurrence rate was 12.26%. Symptoms were relieved in 16 patients after intravenous antibiotic treatment. In the remaining 36 cases (8.49%), the infection was uncontrolled by intravenous antibiotics and surgical debridement was performed. The recurrence rate of infection of the tibia (16.22%) was higher than that of the femur (8.70%). The recurrence rate of post-traumatic osteomyelitis (14.66%) was significantly higher than that of hematogenous osteomyelitis (2.41%). Patients in whom Pseudomonas aeruginosa was isolated at the first stage had a recurrence rate of 28% (7/25), which was higher than that with the other isolated bacteria. Logistic regression analysis showed that repeated operations (≥3), post-traumatic osteomyelitis, and internal fixation at the first stage were risk factors for recurrence of infection, with odds ratios (ORs) of 2.30, 5.53 and 5.28 respectively. CONCLUSIONS: The induced membrane technique is an effective method in the treatment of extremity osteomyelitis, although infection recurs in some cases. Repeated operations, post-traumatic osteomyelitis, and internal fixation at the first stage were risk factors for recurrence of infection. P. aeruginosa isolated at the first stage, tibia osteomyelitis, the presence of sinus, or flaps may also be associated with recurrence of infection.

Risk factors for mortality in the late amputation of necrotizing fasciitis: a retrospective study.

Background: Necrotizing fasciitis (NF) is a rapidly progressive infectious disease that primarily involves the fascia and subcutaneous tissue. If not promptly treated, it can lead to morbidity as well as mortality. It can affect any part of the body, most commonly the extremities. Early and aggressive surgical treatment is the proper way of management. The purpose of this study was to identify the risk factors for mortality in late amputation among NF patients that may be used in routine clinical practice to prevent mortality. Methods: A retrospective cohort study of hospitalized patients with NF was conducted in a tertiary teaching hospital in Taiwan between March 2015 and March 2018. All collected data were statistically analyzed. Results: A total of 582 patients with NF were included; 35 of them had undergone amputation (7 primary and 28 late amputations), with a 6% amputation rate. Thirteen amputated patients still died eventually (all in the late amputation group). Significant risk factors for mortality identified in the late amputation group included hemorrhagic bullae (p = 0.001, OR 4.7, 95% confidence interval (CI) 2.68-8.69), peripheral vascular disease (p < 0.001, OR 3.2, 95% CI 1.12-10.58), bacteremia (p = 0.021, OR 2.87, 95% CI 2.07-5.96), and Laboratory Risk Indicator of Necrotizing Fasciitis (LRINEC) score > 8 (p < 0.001, OR 1.97, 95% CI 1.28-4.61). Vibrio vulnificus was the main causative organism based on our study, but the microbiology results showed no significant correlation. Conclusion: NF patients with hemorrhagic bullae, comorbidity with peripheral vascular disease, presence of bacteremia, or LRINEC score > 8 should receive early and primary amputation in order to prevent mortality.

The location of Australian Buruli ulcer lesions-Implications for unravelling disease transmission.

BACKGROUND: Buruli ulcer (BU), caused by Mycobacterium ulcerans, is increasing in incidence in Victoria, Australia. To improve understanding of disease transmission, we aimed to map the location of BU lesions on the human body. METHODS: Using notification data and clinical records review, we conducted a retrospective observational study of patients diagnosed with BU in Victoria from 1998-2015. We created electronic density maps of lesion locations using spatial analysis software and compared lesion distribution by age, gender, presence of multiple lesions and month of infection. FINDINGS: We examined 579 patients with 649 lesions; 32 (5.5%) patients had multiple lesions. Lesions were predominantly located on lower (70.0%) and upper (27.1%) limbs, and showed a non-random distribution with strong predilection for the ankles, elbows and calves. When stratified by gender, upper limb lesions were more common (OR 1·97, 95% CI 1·38-2·82, p<0·001) while lower limb lesions were less common in men than in women (OR 0·48, 95% CI 0·34-0·68, p<0·001). Patients aged ≥ 65 years (OR 3·13, 95% CI 1·52-6·43, p = 0·001) and those with a lesion on the ankle (OR 2·49, 95% CI 1·14-5·43, p = 0·02) were more likely to have multiple lesions. Most infections (71.3%) were likely acquired in the warmer 6 months of the year. INTERPRETATION: Comparison with published work in Cameroon, Africa, showed similar lesion distribution and suggests the mode of M. ulcerans transmission may be the same across the globe. Our findings also aid clinical diagnosis and provide quantitative background information for further research investigating disease transmission.

[IMPACT OF THE TISSUES OEDEMA ON THE RESULT OF SURGICAL TREATMENT OF INFLAMMATION].

Significance of the tissues oedema and its elimination in the course of inflammation and the wound healing was investigated. There were analyzed the results of treatment of 68 patients, suffering inflammatory and necrotic affection of soft tissues, including 65 ­ a lower one, 3 ­ an upper. In 47 observations the affection course was an acute, while in 18 ­ chronic. In 36 patients (control group) a local and systemic antibacterial therapy were conducted, and in accordance to indications ­ surgical interventions; in 32 (main group) this treatment was added with tight bandaging of the extremity, using elastic bandage. Tight squeezing of tissues with the oedema elimination on background of an adequate antibacterial therapy and surgical sanation of purulent-necrotic focus is accompanied by arrest of infiltrative and exudative stages of an acute inflammation, promotes an active course of the inflammation proliferative stage. While treatment of chronic cutaneous defect, the application of tight squeezing have promoted the granulating shaft resolution, the granulation growth in the wound and its boundary epithelization.

The effect of timing of antibiotic delivery on infection rates related to open limb fractures: a systematic review.

OBJECTIVE: To examine whether the timing of delivery of intravenous antibiotics following open limb fractures has an effect on deep infection rates and other outcomes. DESIGN: We published an a priori study protocol in PROSPERO. Our search strategy combined terms for antibiotics, timing of administration and fractures. Two independent reviewers screened, selected, assessed quality and extracted data from identified studies. DATA SOURCES: We searched five electronic databases with no limits and performed grey literature searches. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised and non-randomised controlled studies, prospective and retrospective observational studies in which the effect of the timing of delivery of antibiotics on the outcome of deep infection in open fractures was considered were included. RESULTS: Eight studies were included according to the above criteria. There were no randomised or non-randomised controlled trials. None of the included studies provided data on patient reported or health-related quality of life. The overall deep infection rate ranged from 5% to 17.5%. All of the studies were at substantial risk of bias. One study reported a reduced infection rate with the delivery of antibiotics within 66 min of injury and seven studies reporting no effect. CONCLUSIONS: Sufficiently robust evidence is not available currently to determine whether the timing of delivery of intravenous antibiotics has an effect on the risk of deep infection or other outcomes following open limb fractures. There is therefore a need for a randomised controlled trial in this area before policy changes should be instigated. TRIAL REGISTRATION NUMBER: PROSPERO (CRD42015016729).

Necrotising fasciitis of the extremities: implementation of new management technologies.

INTRODUCTION: Necrotising fasciitis (NF) is potentially life-threatening soft-tissue infection. Early diagnosis and aggressive surgical debridement are critical to decrease mortality and morbidity. The impacts of new management technologies such as hydro-bisturi-assisted debridement (HAD) and negative pressure wound therapy (NPWT) are not yet clear with respect to treatment of NF. The objective of this study was to describe laboratory (including LRINEC score), clinical and microbiological factors, treatment methods and outcomes related to managing necrotising fasciitis, focusing on the implementation of new treatment methods in our centre. METHODS: From June 2010 to June 2014, adult patients diagnosed with necrotising fasciitis affecting an upper or lower limb that were admitted to our hospital, a referral tertiary care centre, were eligible to participate in this study. Demographic data, clinical features, location of infection, Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC) score on the day of admission, microbiology and laboratory results, use of HAD, wound management using NPWT, and patient outcomes were retrospectively analysed. A univariate risk factor analysis was performed, in an attempt to define prognostic factors for mortality. RESULTS: A total of 20 patients satisfied the inclusion criteria. Type II NF (Group A ß-haemolytic streptococci) was found in 8 cases (40%). The average LRINEC score on the day of admission was 6. The lower extremity was affected in 60% of the cases. All patients were treated operatively, with 2.5 interventions on average. Hydro-bisturi was used in the first debridement in 40% of the cases (8 out 20). In 75% of the studied cases, Negative Pressure Wound Therapy (NPWT) was the technique selected for surgical wound management. The global mortality rate was 30%. On univariate analysis, the only factors significantly associated with mortality were high levels of creatinin (p=0.033) and low blood glucose levels (p=0.012). Finally, four amputations were observed in this series. CONCLUSION: We confirm that necrotising fasciitis (NF) of the extremities, despite new advancements in treatment and critical care management, is still a potentially life-threatening soft-tissue infection (30% mortality). New, advanced wound management modalities have been heavily used in management of necrotising fasciitis, but these have not had significant impacts on morbidity and mortality rates.

Eroded swimmeret syndrome in female crayfish Pacifastacus leniusculus associated with Aphanomyces astaci and Fusarium spp. infections.

We describe a novel syndrome in crayfish, eroded swimmeret syndrome (ESS), affecting wild female signal crayfish Pacifastacus leniusculus. ESS causes partial or total swimmeret erosion. We observed ESS only in female signal crayfish larger than 40 mm carapace length, i.e. sexually mature and probably having carried eggs at least once. The eroded swimmerets were melanised, indicating a crayfish immune system response. We isolated Fusarium tricinctum species complex (SC), F. sambucinum SC, Saprolegnia parasitica and S. australis from the melanised tissue of the eroded swimmerets. ESS includes chronic Aphanomyces astaci infection and a secondary infection by Fusarium sp. In Sweden, we found female signal crayfish with ESS in 6 out of 11 populations with a prevalence below 1% in lakes with commercially productive signal crayfish populations and higher than 29% in lakes with documented signal crayfish population crashes. In Finland, the ESS prevalence was from 3.4 to 6.2% in a commercially productive population. None of the sampled male signal crayfish showed signs of ESS. A caging experiment indicated that females with at least 1 lost swimmeret carried on average 25% fewer fertilized eggs compared to females with intact swimmerets. ESS could significantly reduce individual female fecundity and thus could also affect fecundity at the population level. The decline in reproductive success due to ESS could be among the factors contributing to fluctuations in wild signal crayfish populations.

Evaluation of [¹¹¹In]-labeled zinc-dipicolylamine tracers for SPECT imaging of bacterial infection.

PURPOSE: This study prepared three structurally related zinc-dipicolylamine (ZnDPA) tracers with [(111)In] labels and conducted biodistribution and single-photon emission computed tomography/computed tomography (SPECT/CT) imaging studies of a mouse leg infection model. PROCEDURES: Two monovalent tracers, ZnDPA-[(111)In]DTPA and ZnDPA-[(111)In]DOTA, each with a single zinc-dipicolylamine targeting unit, and a divalent tracer, Bis(ZnDPA)-[(111)In]DTPA, with two zinc-dipicolylamine units were prepared. Organ biodistribution and SPECT and CT imaging studies were performed on living mice with a leg infection created by injection of clinically relevant Gram positive Streptococcus pyogenes. Fluorescent and luminescent Eu(3+)-labeled versions of these tracers were also prepared and used to measure relative affinity for the exterior membrane surface of bacterial cells and mimics of healthy mammalian cells. RESULTS: All three (111)In-labeled radiotracers were prepared with a radiopurity of >90 %. The biodistribution studies showed that the two monovalent tracers were cleared from the body through the liver and kidney, with retained percentage injected dose for all organs of <8 % at 20 h and infected leg target to non-target ratio (T/NT) ratio of ≤3.0. Clearance of the divalent tracer from the bloodstream was slower and primarily through the liver, with a retained percentage injected dose for all organs <37 % at 20 h and T/NT ratio rising to 6.2 after 20 h. The SPECT/CT imaging indicated the same large difference in tracer pharmacokinetics and higher accumulation of the divalent tracer at the site of infection. CONCLUSIONS: All three [(111)In]-ZnDPA tracers selectively targeted the site of a clinically relevant mouse infection model that could not be discerned by visual external inspection of the living animal. The highest target selectivity, observed with a divalent tracer equipped with two zinc-dipicolylamine targeting units, compares quite favorably with the imaging selectivities previously reported for other nuclear tracers that target bacterial cell surfaces. The tracer pharmacokinetics depended heavily on tracer molecular structure suggesting that it may be possible to rapidly fine tune the structural properties for optimized in vivo imaging performance and clinical translation.

Identification of Dermatophilus congolensis from lower leg dermatitis of cattle in Kerala, India.

This study was conducted to identify the aetiological agents associated with a particular type of lower leg dermatitis, locally called pododermatitis, among dairy cattle in Kerala. Skin scabs and scrapings were collected aseptically from 82 naturally occurring cases of lower leg dermatitis in cattle and were subjected to direct microscopical examination and bacterial and fungal culture. Microscopical examination of the skin scrapings with 10% potassium hydroxide revealed fungal spores in hair shafts from only two samples and did not reveal the presence of mites or other parasites. Fungal culture yielded dermatophytes from only five samples; these were identified as Trichophyton mentagrophytes in two cases, T verrucosum in one case, Epidermophyton floccosum in one case and Microsporum nanum in one case. Microscopical examination of Giemsa- and Gram-stained smears of the scab material from the lesions from 72 cases revealed characteristic Gram-positive septate branching filaments with multiple rows of spherical to ovoid cocci, with a typical 'tram-track' appearance suggestive of Dermatophilus congolensis. Culture of the scab materials on sheep blood agar in the presence of 10% carbon dioxide yielded typical beta haemolytic colonies of D. congolensis from 75 samples. The isolates were further confirmed by the macroscopic and microscopic morphology of the colonies, and biochemical test results. This study confirmed the presence of dermatophilosis caused by D. congolensis in cattle in Kerala.

Pancytopenia due to lepromatous involvement of the bone marrow: successful treatment with multidrug therapy.

Leprosy is a chronic infectious disease with a wide spectrum of signs and symptoms depending on the ability of the host's immune system to resist the infection. The disease is frequently associated with sensory loss in skin lesions and damage in peripheral nerve trunks leading to nerve function impairment. In lepromatous leprosy, the immune system offers no protection against the multiplying bacilli and this results in heavy infiltration of the internal organs. We report a case of florid lepromatous leprosy with bone marrow suppression due to the disease, presenting with anemia, leukocytopenia and thrombocytopenia. The hematological abnormalities were fully reversed by mutidrug therapy for leprosy. We suggest that infiltration of the bone marrow by Mycobacterium leprae can cause pancytopenia, which can be cured by treatment of the leprosy alone.

[Recent advances in research on Malassezia microbiota in humans].

Malassezia species of lipophilic yeasts account for most fungal microbiota. Although they colonize healthy skin, they are also associated with several skin diseases, including pityriasis versicolor, seborrheic dermatitis, Malassezia folliculitis, and atopic dermatitis. To date, 14 members of the Malassezia genus have been identified. Of these, both M. globosa and M. restricta predominate, regardless of skin-disease type. Comprehensive analysis of fungal microbiota in the skin of patients with atopic dermatitis using an rRNA clone library method revealed that fungal microbiota cluster according to disease severity. The external ear canal and sole of the foot are colonized by specific Malassezia microbiota.

Successful treatment of a severe case of fusariomycosis in a beluga whale (Delphinapterus leucas leucas).

An adult male beluga whale (Delphinapterus leucas leucas) was presented with a 4-cm-diameter, raised, firm nodule on the medial aspect of the left pectoral fin. A fissure developed within the center of the nodule, which formed an ulcerated cyst-like lesion. The lesion rapidly progressed in size, and, with peeling of material present within the cyst, the lesion flattened to a 36 x 25-cm cutaneous ulcer that extended into the axilla. Histopathologic features were consistent with lymphocytic and suppurative dermatitis with intralesional fungi. Fusarium solani was diagnosed by polymerase chain reaction (PCR). Fungal susceptibility testing was performed and revealed drug resistance to multiple antifungal medications tested individually and in combination therapies. Treatments used included serial surgical debridement of affected and surrounding tissue, topical application and regional infusion of various azole, and allylamine antifungals combined with either dimethyl sulfoxide or Tricide for absorption potentiation, and oral voriconazole administration. Although susceptibility testing revealed resistance to voriconazole, visible improvement of the lesion was noted after 6 weeks of oral voriconazole therapy. The voriconazole dosage was tapered based on serum levels and was administered over a 12-mo period. No local recurrence or new lesions were visible by 14 mo from first presentation.

Autopsy cases of fulminant bacterial infection in adults: clinical onset depends on the virulence of bacteria and patient immune status.

To assist physicians in recognizing the potentially fatal onset of symptoms in cases of fulminant bacterial infection, we analyzed 11 autopsy cases of such infection (four caused by Streptococcus pneumoniae, four by S. pyogenes, one by S. dysgalactiae subsp. equisimilis, one by Staphylococcus aureus, and one by Vibrio vulnificus). Clinicohistopathologic features were evaluated. All patients experienced sudden onset of hypotension and multiple organ failure, leading to unexpected death. Blood culture confirmed bacteremia. The main chief complaints were gastrointestinal symptoms (45%) and limb pain (36%). All had an underlying chronic illness (82%), e.g., a hematologic disorder (36.3%) or liver cirrhosis (27.2%). Necrotizing fasciitis occurred in only 55% of cases, with none involving pneumococcal infection. Laboratory tests typically showed C-reactive protein elevation but without leukocytosis, indicating a high-level inflammatory state. In ten cases, death was attributed to circulatory collapse due to sepsis; severe pulmonary congestion and hemorrhage were present in these cases. The onset of fulminant bacterial infection depends on both virulence of the bacterium and status of the host defense system.

Experimentally induced marine flexibacteriosis in Atlantic salmon smolts Salmo salar. II. Pathology.

The fish disease marine flexibacteriosis is characterised by necrotic lesions on the body, head, fins, and occasionally gills, with erosive lesions on the external surface as the prominent clinical sign. In Australia, the main species affected are Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss in sea-cage culture in Tasmania. Using a dose-dependent trial to determine pathology, 2 forms of the disease were noted in Atlantic salmon. The acute form occurs within 2 to 3 d after inoculation at high doses (1 x 10(8) cells ml(-1)) and is characterised by the disintegration of the epithelium. The chronic form of the disease began as small superficial blisters of the epidermis, which develop into ulcerative lesions that leave musculature exposed. The predominant lesion sites were the dorsum and pectoral fins. Jaws were commonly affected, and gill necrosis was also noted. Behaviour of Atlantic salmon as well as the conditions under which they were kept contribute to the size and distribution of lesions observed. Lack of an inflammatory response in pathology and rapid and destructive mortalities observed in higher inoculum doses suggested a role of toxins in the pathogenesis of Tenacibaculum maritimum. This is the first study to examine the development of marine flexibacteriosis lesions and to utilise immunohistochemistry to verify that the bacteria observed in histology was T. maritimum.