Efficacy of intralesional meglumine antimoniate in the treatment of canine tegumentary leishmaniasis: A Randomized controlled trial

Dogs living in areas of Leishmania (Viannia) braziliensis transmission may present canine tegumentary leishmaniasis (CTL) characterized by cutaneous or muzzle ulcers as well as asymptomatic L. braziliensis infection. It is not clear if dogs participate in the transmission chain of L. braziliensis to humans. However, dogs may remain with chronic ulcers for a long time, and as there are no public policies about CTL, these animals die or are sacrificed. Here we compare the efficacy of intralesional meglumine antimoniate with intralesional 0.9% NaCl solution in CTL treatment. This randomized control study included 32 dogs with cutaneous or muzzle lesions who had L. braziliensis DNA detected by PCR in tissue biopsied. Group one received 5ml of intralesional Glucantime, and group two received 5ml 0.9% NaCl solution, both applied in the four cardinal points on days 0, 15, and 30. Cure was defined as complete healing of the ulcers in the absence of raised borders on day 90. There was no difference in animals' demographic and clinical features in the two groups (p >.05). While at the endpoint, the cure rate was 87.5% in the group test, and in those who received 0.9 NaCl the cure rate was only 12.5%. As important as the high cure rate, the healing time was faster in dogs treated with antimony than in those treated with saline (p < .001). Intralesional meglumine antimoniate is effective in the treatment of dogs with L. braziliensis infection and accelerates the healing time of CTL.

Immunohistochemical diagnosis of tenacibaculosis in paraffin-embedded tissues of Senegalese sole Solea senegalensis Kaup, 1858

A sensitive and specific immunohistochemical technique was developed to improve the diagnosis of tenacibaculosis and to better understand its pathogenesis. Senegalese sole Solea senegalensis Kaup, 1858 were inoculated subcutaneously with a bacterial suspension of Tenacibaculum maritimum, and samples were taken at different hours post-inoculation. Sections from different organs were used as positive controls. In addition, a total of 128 field samples from different organs collected from tenacibaculosis outbreaks were used. Tenacibaculum maritimum antigens were detected in several organs of experimentally infected Senegalese sole and in at least one of the tissues from fish suffering from natural tenacibaculosis previously confirmed by culture and PCR-based methods. In fish collected during outbreaks, a strong positive reaction was detected in ulcerative skin areas. Moreover, bacterial antigen was identified inside scale pockets and in sites of the skin with mild lesion. In kidney and spleen, evident immunostaining of bacterial antigen was detected in both naturally and experimentally infected fish. Besides, the presence of T. maritimum in the intestinal tract without associated histological changes suggests that this organ may act as a reservoir for T. maritimum. The results of this study confirm the usefulness of IHC for the diagnosis of tenacibaculosis in paraffin-embedded tissues.

Morphopathological features of a severe ulcerative disease outbreak associated with Tenacibaculum maritimum in cultivated sole, Solea senegalensis (L.)

This study describes morphopathologic changes in naturally infected farmed Senegalese sole affected by tenacibaculosis caused by Tenacibaculum maritimum. Macroscopic observation, in addition to light microscopy and scanning electron microscopy, was used to study the lesions. Main lesions were characterized by complete loss of epidermis and dermis, as well as extensive necrosis of muscle layers. Mild-to-moderate inflammatory response with the presence of macrophages was noted around hyaline degenerated muscle cells. Gram-negative filamentous bacteria could be detected only at the dermis. Under scanning electron microscopy, filamentous bacteria located over the scales without epithelium could be observed. These findings together with the isolation and PCR detection of the bacteria in kidney and skin tissues suggest that once the bacteria reach the dermis, probably through eroded epidermis, they are able to proliferate and produce enzymes that are responsible for the damage in the underlying tissues.

Assessment of work ability of health professionals in the mobile emergency unit

Ergonomics is the study of a workplace and the worker. Its aim is to better adapt the workplace to man by preserving the body for short and long term work. This helps to adjust and improve functionality, thus preserving the body for short and long term work. It was through the observation of SAMU's (Mobile Emergency Unit) professional's helpers that the interest to evaluate these individuals arose. In addition, the aim of this research is to investigate the work ability of health professionals that work for SAMU/JP. The population was composed of 97 health professionals who currently work for SAMU/JP. A sociodemographic questionnaire was used as data collection instrument and it was validated by the index of the Work Ability (WAI). The research took place in 2010, in the headquarters of SAMU, in the city of João Pessoa, state of Paraíba - Brazil. The data analysis was carried out by simple descriptive statistics followed by comparison of the results with the pertinent literature. The quantity of daily sleeping hours, the levels of satisfaction in the job and the number of diagnosed diseases were among the most worrying factors. In spite of this, the health professionals obtained a work ability average considered to be "good".

Relationship between exposure to cement and the incidence of respiratory diseases in children: a preventive perspective

Respiratory disease in childhood is a factor of concern to health professionals, resulting in a primary determinant of lung function in adulthood. Studies indicate that people placed in areas with established industries, are exposed to pollutants from many industrial processes, thus increasing the risk of diseases. The aim was to examine the connection between exposure to cement and the incidence of respiratory diseases in the Jardins Community. It was a field study, descriptive, conducted in a community in the city of Cabedelo- PB, and result in a qualitative-quantitative approach. The sample comprised 51 children aged between 1 to 12 years who have symptoms or diagnosis of respiratory disease. The survey data was obtained by applying a semistructured interview, and analysed using chi-square, MacNemar and Mann-Whitney tests for statistical analysis. A high number of complaints about environmental pollution, small houses and subdued, lack of paving and sanitation, a high frequency of respiratory symptoms and especially the occurrence of the onset of symptoms after arrival in the community were found. There is a correlation between environmental exposure and the incidence of respiratory diseases in children; therefore the community requires specific actions to reduce the exposure.

Phenotypic Characteristics and Virulence of Vibrio anguillarum-Related Organisms

The phenotypic, molecular, and virulence properties of 46 Vibrio anguillarum-related (VAR) strains isolated from diseased fish and shellfish and from the environment were investigated. Twelve reference strains belonging to the 10 serotypes of V. anguillarum and the Vibrio splendidus type strain were included for comparison. Numerical taxonomy studies allowed us to group the isolates into four phena. The main phenotypic traits to differentiate VAR strains from V. anguillarum were fermentation of arabinose and mannitol, indole and Voges-Proskauer reactions, gelatin and casein hydrolysis, hemolytic activity, growth at 37 and 4 degrees C, and resistance to ampicillin. Serological analysis confirmed that phena I and II were composed mainly of strains of V. anguillarum, while phena III and IV included VAR strains. Excluding the reference strains, the typeable isolates belonged to serotypes O3 (15 strains), O4 (3 strains), and O5 (2 strains) of V. anguillarum. The infectivity trials showed that only 9 of a total of 24 strains tested displayed virulence for rainbow trout. Virulent strains (50% lethal dose ranging from 10 to 10 cells) included V. anguillarum strains belonging to serotypes O1 (one strain), O2 (one strain), O3 (three isolates), and O4 (one isolate) and only three strains of the VAR group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of lipopolysaccharide and outer membrane proteins showed heterogeneity not only among the 10 V. anguillarum serotypes but also within the VAR group. Immunoblot assays demonstrated a close relationship among V. anguillarum strains from the same serotype, while strains from different serotypes were not antigenically related. The VAR strains did not share antigenic components with the serotypes of V. anguillarum tested (serotypes O1 to O5). Plasmids were detected in only 19 of the total of 59 strains. The majority of the strains carrying plasmids were grouped within phenon IV, in which plasmid bands of 27 and 36 MDa were found in all the isolates. No correlation between the plasmid content of VAR microorganisms and their phenotypic or virulence characteristics was observed. From these results it can be concluded that VAR strains associated with disease should be included together with V. anguillarum in the formulation of vaccines against vibriosis.

Fatty acid analysis as a chemotaxonomic tool for taxonomic and epidemiological characterization of four fish pathogenic Tenacibaculum species

AIMS

In this work, fatty acid content and profiles were analysed in order to differentiate the species Tenacibaculum maritimum, Tenacibaculum gallaicum, Tenacibaculum discolor and Tenacibaculum ovolyticum that are pathogenic for cultured marine fish and to assess the potential of fatty acid profiles as a tool for epizootiological typing.

METHODS AND RESULTS

The fatty acid methylesters (FAMEs) were extracted from cells grown on marine agar for 48 h at 25 degrees C and were prepared and analysed according to the standard protocol of the MIDI/Hewlett Packard Microbial Identification System. The cellular fatty acid profiles of Tenacibaculum strains tested were characterized by the presence of large amounts of branched (36.1-40.2%) and hydroxylated (29.6-31.7%) fatty acids. The FAME products from the four species significantly (P < 0.05) differed in the content of iso-C(15:0)3-OH, iso-C(16:0)3-OH, iso-C(15:1)G, summed feature 3 (a component that contains C(16:1)omega7c and/or iso-C(15:0) 2-OH), iso-C(16:0), C(17:1)omega6c, C(15:0)3-OH, iso-C(17:0)3-OH.

CONCLUSIONS

Results of present study demonstrated the existence of differences in the fatty acids content between the T. maritimum isolates from different marine fish/geographical origin and between strains of T. maritimum, T. discolor, T. gallaicum and T. ovolyticum.

SIGNIFICANCE AND IMPACT OF THE STUDY

Profiling of fatty acids may be a useful tool to distinguish T. maritimum from other Tenacibaculum species pathogenic for fish as well as for epizootiological differentiation of T. maritimum isolates.

Efficacy of furunculosis vaccines in turbot, Scophthalmus maximus (L.): evaluation of immersion, oral and injection delivery

The commercial furunculosis vaccine Aquavac Furovac 5 and an autogenous vaccine, based on the challenge strain, induced immune protection in turbot, Scophthalmus maximus (L.), as shown in challenge tests 120 days post-immunization by injection (relative percentage of survival, RPS = 72-99%). This protective effect lasted for at least 6 months post-immunization at appreciable levels (RPS = 50-52%). Neither the autogenous vaccine nor the commercial vaccine was able to induce significant levels of protection against Aeromonas salmonicida in turbot when administered by immersion. Antibody levels were high or moderate in fish vaccinated by injection with the different vaccines and very low in fish vaccinated by immersion. The field results show that delivering an oral boost after the primary vaccination by injection did not enhance protection of turbot against furunculosis and that water-based (autogenous vaccine) and oil adjuvanted (Alpha Ject 1200) vaccines administered by injection conferred similar levels of protection (RPS > 80%) in turbot.

Evaluation of the AQUARAPID-Va, AQUAEIA-Va and dot-blot assays for the detection of Vibrio anguillarum in fish tissues

The comparative accuracy of the serological assays AQUARAPID-Va, AQUAEIA-Va (BIONOR AS), and dot-blot for a rapid diagnosis of vibriosis in fish was evaluated. Twenty-one Vibrio anguillarum strains, representative of pathogenic and environmental serotypes, and 13 strains of other fish pathogenic bacteria were used to assess the sensitivity and specificity of the detection methods. The serological assays tested detected all the strains of V. anguillarum serotypes O1 and O2. The dot-blot assay was the most specific and sensitive method, detecting almost all isolates from serotypes O1, O2 and O3, with an average sensitivity of 1 x 10(6) bacteria g(-1) of fish tissue. The AQUARAPID-Va and the AQUAEIA-Va systems were able to detect 5 x 10(6) and 5 x 10(7) bacteria g(-1) of fish tissue, respectively. The simplicity, effectiveness and speed of the AQUARAPID-Va system confirmed this method as the most suitable serological test for the detection of V. anguillarum in field analysis and small-scale laboratory studies.

Detection of Flexibacter maritimus in fish tissue using nested PCR amplification

A nested polymerase chain reaction (PCR) system was developed for the detection of Flexibacter maritimus from fish tissue. The total procedure for the diagnosis of marine flexibacteriosis, from the point of DNA extraction to the electrophoretic analysis, can be performed in < 4 h. This was achieved by the combination of a short thermal cycling programme with a rapid DNA extraction procedure. The assay was extremely sensitive, capable of detecting as few as 75 cfu mg(-1) fish tissue. The accuracy of the nested PCR was confirmed under field conditions using tissue samples recovered during 1993-2002 from fish suffering marine flexibacteriosis. The nested PCR method proved to be efficient for the rapid and sensitive detection of F. maritimus from fish tissues and can be used for routine diagnosis of the disease caused by this pathogen.

A proposed serotyping system for Flavobacterium psychrophilum

AIMS

To develop a common serological system for rapid and routine identification of the fish pathogen Flavobacterium psychrophilum.

METHODS

Thirty-four isolates of Fl. psychrophilum from different fish species and different geographical areas were typed using a slide agglutination test and an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Seven host-dependent serovars (1: salmon; 2: trout; 3: trout; 4: eel; 5: carp; 6: tench; 7: ayu) were found. Serovar 2 was divided into two antigenic subgroups (2a and 2b). The results achieved by both slide agglutination and ELISA methods were totally consistent with each other. Although both techniques proved to be simple to carry out and useful, only the ELISA allowed identification of Fl. psychrophilum serovars using unabsorbed antiserum and whole-cells as antigens.

SIGNIFICANCE AND IMPACT OF THE STUDY

This paper proposes a harmonized scheme for serological identification of Fl. psychrophilum to be used for diagnostic and seroepidemiological studies of the diseases it causes.

Presence of high-affinity iron uptake systems in fish-isolated and environmental strains of Vibrio anguillarum serotype O3

This work describes the presence of high-affinity iron uptake systems in Vibrio anguillarum serotype O3 strains (subgroups A and B), isolated from diseased fish and environmental samples, as well as the presumptive effect of iron on their virulence. All strains demonstrated an ability to grow under iron-limiting conditions, production of catechol-type siderophores and synthesis of iron-regulated outer membrane proteins. However, clear differences were found depending on the isolation source, suggesting a more efficient iron uptake system in fish-isolated strains. Comparing the iron-regulated outer membrane protein profiles with those described for O1 and O2 serotypes, we found a protein which is specific for serotype O3, and another one that allows the differentiation of serotype O3 fish isolates from environmental strains. Moreover, only the strains showing this protein increased their virulence when iron was added to the inoculum in pathogenicity assays.

Rapid and low-level toxic PCR-based method for routine identification of Flavobacterium psychrophilum

We describe a rapid, low-toxicity and simple method for the detection of the bacterial fish pathogen Flavobacterium psychrophilum. The method, based on the polymerase chain reaction (PCR), combined the electrophoresis of PCR products in a vertical agarose gel and a modified methylene blue stain. DNA was amplified directly either from bacterial suspensions or from tissues experimentally infected with F. psychrophilum, using different non-toxic commercial DNA extraction kits. The protocol allowed to detect 15 to 150 cells of the pathogen in bacterial suspension, without prior DNA extraction, and 7500 to 75,000 cells in seeded spleen tissue and ovarian fluid using Dynabeads DNA DIRECT extraction system. This method, which has the advantage of not using hazardous products, is proposed as a fast tool for routine identification of F. psychrophilum.

Immunization with bacterial antigens: Vibrio infections

Within the genus Vibrio, the species causing the most economically important diseases in marine culture are Vibrio anguillarum, V. ordalii, V. salmonicida and V. vulnificus biotype 2. For these bacterial fish pathogens host range, clinical importance, virulence mechanisms, the antigenic variants relevant to vaccination, the existence of genetic intraspecific diversity and the available vaccines including commercial or domestically produced will be described. Among the 10 serotypes described in V. anguillarum, only serotypes O1, O2 and O3 have been associated with mortality in a great variety of farmed and feral fish worldwide. Whereas serotype O1 is a very homogeneous group from the biochemical, serological and genetic stand-point, within serotype O2 and O3 two antigenic entities have been detected. Moreover these two serotypes present a remarkable genetic heterogeneity. However, many of the available commercial vibriosis vaccines include in their formulations only V. anguillarum serotype O1 in combination with V. ordalii (formerly V. anguillarum biotype 2). In addition no commercial vaccine provides information about the subgroup(s) used as representative of V. anguillarum O2. Recently, Vibrio species taxonomically related to V. anguillarum (VAR) have been isolated from diseased fishes. An extensive characterization of these VAR organisms allowed us to distribute them into at least seven O-serogroups. The inclusion of representative VAR strains in the vibriosis vaccines need to be discussed. V. ordalii, V. salmonicida and V. vulnificus are homogeneous species with respect to biochemical reactions, serology and degree of virulence, possess a narrow host range and seem to be restricted to some geographic areas. Although iron acquisition systems can be involved in the virulence mechanisms of these pathogens, only in V. anguillarum has it been clearly demonstrated that the ability to scavenge iron from the host is a crucial virulence determinant. The role of exotoxins and cell surface associated properties in the Vibrio infections remains to be elucidated.

Immunological analysis of extracellular products and cell surface components of motile Aeromonas isolated from fish

The present work describes the characterization of antigens present in the extracellular products (ECP) and cell wall of strains of motile Aeromonas isolated from rainbow trout culture systems. The relationships among virulence for fish, O-serogroup and profile of LPS were also examined. The slide agglutination test showed that most of the virulent strains of motile Aeromonas (72%) were included in the serotypes O3, O6, O11 and O19 (Guinée and Jansen System). However, there were also non-pathogenic strains within these groups. Electrophoretic analysis of lipopolysaccharides (LPS) and proteins from cell envelope and ECP showed heterogeneity not only among the different serogroups but also within the same serotype. Immunoblot assays of cell envelope components, and of LPS present in the ECP demonstrated a close relationship among Aeromonas strains from the same serotype, while strains from different serotypes were not immunologically related. Moreover, this assay showed that motile Aeromonas belonging to distinct serotypes produced extracellular proteins immunologically related. On the other hand, antigenic cross reactivity was observed between the LPS obtained from cell envelope and those obtained from the ECP. The present results point out the need to include strains representative of each of the serotypes which predominates in a particular area and their ECPs in the formation of vaccines against motile Aeromonas septicaemia.

Growth of the fish pathogen Renibacterium salmoninarum on different media

In the present study, the ability of a group of Renibacterium salmoninarum strains to grow in the presence or absence of the amino acid cysteine and other mineral and organic sources of sulfur and nitrogen has been evaluated. Most of the isolates tested were able to grow on a mineral media supplemented with L-cysteine-HCl or other organic compounds, such as the vitamin thiamine and a casein hydrolysate (Bacto Casamino Acids, Difco). Bacterial growth was also recorded on commercial and specific media not supplemented with L-cysteine-HCl, or in which this amino acid was replaced by the compounds cited above.

Analysis of antigens present in the extracellular products and cell surface of Vibrio anguillarum serotypes O1, O2, and O3

Antigens present in the extracellular products (ECP) and cell walls of strains of Vibrio anguillarum of serotypes O1, O2, and O3 isolated from different fish species in distinct geographic areas were characterized. The usefulness of slide agglutination, dot blot assay, and quantitative agglutination for subtyping V. anguillarum serovars was also evaluated. The three serological assays used to establish the serogroups within V. anguillarum isolates demonstrated that serotype O1 constitutes a homogeneous group, whereas within serotypes O2 and O3, two different patterns of serological reactions were detected. Among the three serological methods used, only dot blot and quantitative agglutination assays differentiated subgroups within serotypes O2 and O3 with unabsorbed sera. Electrophoretic analysis and immunoblot assays of cell envelope and ECP components showed that strains belonging to serotype O1 possessed immunologically related lipopolysaccharide (LPS) and proteins, while V. anguillarum isolates grouped in serotypes O2 and O3 exhibited internal heterogeneity in their LPS and protein banding patterns. On the other hand, although the LPS present in the ECP and those obtained from cell envelopes of V. anguillarum strains showed apparently different gel patterns, a strong relationship between both types of LPS was seen by immunoblot assay. From these results, it can be concluded that V. anguillarum strains representative of each of the antigenic groups (O1, O2 alpha, O2 beta, O3A, and O3B) and their ECPs should be included in the formulation of vaccines against vibriosis in areas where the three serotypes coexist.

Organ donation in the Hispanic population: dondé estan ellos?

Few studies have investigated organ donation among Hispanics, although in major US cities, Hispanics, like African Americans, make up a large percentage of the general population. In fact, the 1990 census reports that of all Hispanics in the country, 90% live in urban areas. The tendency for Hispanics to use hospital emergency rooms rather than visit a physician's office may result in an inadequate exchange of information between minority patients and health-care providers. Hospitals that serve minority populations have been reported to have the lowest organ procurement rates. These hospitals are often funded by local, county, or state funds and are usually dedicated to a patient mix that is largely indigent. The heavy work load of health-care providers who often have limited resources does not lend itself to an adequate exchange of information between patients and health-care providers. The existence of this type of environment impacts on patient communication, increases the fear of complication, and may diminish the discussion of potential organ procurement. There are multiple individual and structural reasons for the high family refusal rates among Hispanics. Procurement specialists may see a proportionally small number of Hispanic families, mainly due to a lack of referrals from hospital staff concerning possible Hispanic donors. White procurement workers may not be familiar with the Hispanic family makeup and cultural attitudes. Organ procurement workers may not pursue the issue of donation with Hispanic families as much as they do with white families. Whatever the reason, if we are to increase organ donation in the Hispanic community, these complex issues will need to be addressed.

Pathogenic activities of live cells and extracellular products of the fish pathogen Pasteurella piscicida

The pathobiological activities in vivo and in vitro of live cells and extracellular products (ECP) of eleven Pasteurella piscicida strains of different origin were examined. Infectivity trials showed that P. piscicida did not possess strict host specificity since the majority of the isolates were virulent for gilthead seabream, rainbow trout and turbot, with LD50 values ranging between 10(3) and 10(6) live cells. However, none of the strains tested were pathogenic for mice (LD50 > 10(8) cells)). In addition, the ECP were strongly toxic for fish (LD50 ranging from 1.0 to 4.6 micrograms protein per g fish), which clearly demonstrates their important role in the pathogenesis of pasteurellosis. All the ECP samples were cytotoxic for fish and homoiothermic cell lines, possessed notable phospholipase activity and displayed haemolytic activity for sheep, salmon and turbot erythrocytes (but not for trout erythrocytes). However, the production of proteolytic enzymes differed among the P. piscicida strains. Although no strain displayed elastase activity, five isolates (the Japanese and Italian strains) hydrolysed casein and gelatin. All these biological activities in vivo and in vitro were lost after heat treatment (100 degrees C for 10 min). The general enzymic patterns of both live cells and ECP evaluated by the API-ZYM system also revealed some variation among the P. piscicida isolates. Generally, whole cells showed a wider range of enzymic activities than ECP. The results presented here are important for the selection of strains in the development of effective polyvalent pasteurellosis vaccines containing both whole cells and ECP.

Detection of a vascular permeability factor in the extracellular products of Renibacterium salmoninarum

The presence of vascular permeability factors in the extracellular products (ECP) of 10 strains of Renibacterium salmoninarum with different geographical origin and serological characteristics are reported. All the ECP produced haemorrhagic and/or oedematous zones at the injection site with a diameter ranging from 10-30 mm. However, the ECP samples did not display toxic effect in fish at the same dose as inoculated in rabbit (180-400 micrograms protein/0.1 ml). No differences were observed in the production of this dermatotoxic factor between the two antigenic groups found in this microorganism. Whereas heating (80 and 100 degrees C/15 min) the ECP samples resulted in a complete loss of their proteolytic activity, only a decrease (but not total inactivation) of the dermatotoxic effects was detected. Therefore, although proteases could be implicated in the permeability factor, they are not totally responsible for this activity.

The detection of two antigenic groups among Renibacterium salmoninarum isolates

The analysis of the membrane proteins and their antigenic properties in a group of 14 geographically diverse strains of Renibacterium salmoninarum revealed the existence of antigenic diversity within this species. Eleven isolates, including the type strain ATCC 33209, shared a similar protein profile with a major component of 57 kDa whereas three strains showed a common pattern with a major protein of 30 kDa. The quantitative agglutination tests and Western blotting assays seem to indicate the existence of serological heterogeneity, with two distinct groups being detected.

An extracellular acetylcholinesterase produced by Aeromonas hydrophila is a major lethal toxin for fish

A hitherto unrecognised lethal toxin from the extracellular products (ECP) of Aeromonas hydrophila is described. The pure toxin was 300 times more toxic than the crude ECP and is the most toxic substance so far described from this bacterium, with a minimum lethal dose of 0.05 micrograms g-1 fish. The toxin had high acetylcholinesterase activity and occurred in native ECP as a monomeric 15.5 kDa polypeptide. The purified toxin had five isoelectric focusing forms ranging from pl 4.45 to 4.70. The ECP of each of six strains of A. hydrophila isolated from fish possessed acetylcholinesterase activity suggesting that the toxin is common in this species. The toxin was not a cytolysin and produced no gross pathology in injected fish. Its enzymic nature, low lethal dose, lack of tissue pathology and its apparent narcotic effect suggest that this toxin may act upon the central nervous system of the fish.

MICs and MBCs of chemotherapeutic agents against Renibacterium salmoninarum

The efficacies of 21 chemotherapeutic agents for controlling bacterial kidney disease were evaluated. The bactericidal and/or bacteriostatic effects of these drugs were tested against 11 Renibacterium salmoninarum strains with different origins. The most effective compounds displaying both bacteriostatic and bactericidal activity for all the isolates were tetracycline and erythromycin, with MICs ranging from less than 0.62 to 10.95 micrograms/ml for tetracycline and from less than 0.62 to 5.47 micrograms/ml for erythromycin. Whereas tetracycline showed identical MICs and MBCs, erythromycin showed bactericidal effects at concentrations of 5.47 to 21.87 micrograms/ml. Similarly, cefazolin and tiamulin proved to be very effective bactericidal compounds against the majority of R. salmoninarum isolates, with MBCs for 90% of the strains tested of 21.87 and 10.95 micrograms/ml, respectively. Neither nitrofuranes, quinolones, nor sulfonamides showed inhibitory effects on the growth of the strains.

Plasmids and factors associated with virulence in environmental isolates of Vibrio cholerae non-O1 in Bangladesh

Plasmid profiles and factors associated with toxigenicity in 51 strains of Vibrio cholerae non-O1 isolated from water samples collected in Bangladesh were analysed. Eleven (21.5%) strains were found to harbour at least one plasmid of 1.7-115 Mda; seven of these strains shared a 115-Mda plasmid. Six of 13 strains tested gave positive cytotoxic and enterotoxic responses. However, two non-cytotoxic strains were enterotoxigenic. Only three of the six cytotoxic and enterotoxic strains caused haemagglutination of human erythrocytes which indicated that toxin production and haemagglutinating activity were unrelated in these V. cholerae non-O1 strains. Conjugal transfer assays demonstrated that the 115-Mda plasmid harboured by some of the toxigenic V. cholerae non-O1 strains carried genes coding for antibiotic resistance and cytotoxin production but not for enterotoxin production. However, this plasmid was also carried by non-toxigenic strains. Some other strains carrying no plasmids or only small-mol.-wt plasmids, were found to be toxigenic. Therefore, toxin production is not plasmid-mediated in all V. cholerae non-O1 strains. Regardless of their pathogenic potential, V. cholerae non-O1 strains possessed the capacity to grow in conditions of iron limitation and, under these conditions, synthesis of at least two new outer-membrane proteins was induced.

Influence of the growth conditions on the hydrophobicity of Renibacterium salmoninarum evaluated by different methods

The influence of medium and salinity on the cell surface hydrophobicity of Renibacterium salmoninarum was investigated using three different methods: bacterial adherence to hydrocarbons (BATH), salt agglutination test (SAT), and binding to nitrocellulose filters (NCF). The possible relationship among hydrophobicity, haemagglutination and adherence to cell lines was also evaluated. R. salmoninarum showed to be highly hydrophobic regardless of the growth conditions or technique employed. Nevertheless, slight differences can be detected depending on the method used. In the SAT and NCF assays very uniform values were obtained within the strains. All the R. salmoninarum isolates agglutinated in (NH4)2SO4 in a range of 0.05-0.2 M and displayed a 77-100% of adherence to nitrocellulose filters. However, more variable results were observed in the BATH method depending on the hydrocarbon, buffer and strain employed. Although all of the isolates produced haemagglutinins for homeotherm erythrocytes, the majority of them failed to agglutinate poikilothermic red blood cells and were unable to adhere to fish cell lines. Therefore, a general correlation among hydrophobicity, agglutinating capacity for fish erythrocytes and adherence to fish cells can not be established for R. salmoninarum.

Evaluation of Different Assay Systems for Identification of Environmental Aeromonas Strains

Important biochemical reactions in conventional tests were compared with counterpart reactions in two multiple test systems, API-20E (Analytab Products, Plainview, N.Y.) and Aeromonas hydrophila medium, to evaluate their accuracy for the identification of motile Aeromonas spp. isolated from fish. In a total of 49 Aeromonas spp. isolates and 10 A. hydrophila reference strains, false-negative or -positive reactions were detected in the Voges-Proskauer test, indole production, gelatinase activity, production of gas, fermentation of arabinose, and lysine decarboxylase reaction. A good correlation was found, among the three identification systems, for the fermentation of mannitol and inositol as well as for the arginine dihydrolase and ornithine decarboxylase tests. The failure of A. hydrophila medium in the detection of gas indicates that this medium is not entirely suitable for defining aerogenic or anaerogenic strains. From the results of the present study, we consider that of the identification method and taxonomic scheme to be adopted for environmental Aeromonas spp. must be standardized.