Hemolytic and elastolytic activities influenced by iron in Plesiomonas shigelloides

The aim of this study was to determine the presence of hemolytic and elastolytic enzymes in several strains of Plesiomonas shigelloides in relation to the availability of iron in culture media. Hemolytic activity and elastolytic activity were detected in strains of P. shigelloides and were enhanced when the strains were grown in an iron-depleted medium and lost after thermal treatment at 100 degrees C for 10 min. Also, elastolytic activity was inactivated by phenylmethyl sulfonyl fluoride, an inhibitor of serine proteases. Hemolytic activity was detected extracellularly in cell-free supernatants, whereas elastin degradation activity was cell associated. Both activities may be related to the virulence of P. shigelloides.

[A validity study of continuous Doppler]

INTRODUCTION

Ultrasound is regularly used for the detection of carotid stenosis which can be treated surgically. This technique includes continuous Doppler, which together with study of blood flow in the orbit is very useful and should be used systematically, not only in certain cases. We present a study of the usefulness of this technique in our Cerebral Vascular Pathology Laboratory.

PATIENTS AND METHODS

We selected 708 patients studied sequentially over 10 years with continuous Doppler and conventional angiography (gold standard). The data obtained independently with each technique were compared in order to establish the degree of concordance between them and the corresponding indicators of validity. Contingency tables were drawn up for different cut-off points corresponding to the different degrees of stenosis (50, 70 and 100%). The parameters for validity (sensitivity, specificity, predictive value and precision) were calculated in each case.

RESULTS

The percentage coincidence of the two techniques was 91.95%. At the cut-off points there was a high degree of precision (> 94.35%). The specificity and negative predictive value of Doppler compared with angiography was over 95% and 96% respectively.

CONCLUSIONS

The validity markers obtained in our laboratory support the technique using continuous Doppler as the ideal non-invasive diagnostic method for carotid stenosis and this means that its systematic use is to be recommended in patients with suspected extracranial carotid disease. Moreover, the low cost of the equipment used as compared with other more sophisticated techniques should lead to its more widespread use as a first-line diagnostic method in all Neurology departments.

Bacterial microflora of wild brown trout (Salmo trutta), wild pike (Esox lucius), and aquacultured rainbow trout (Oncorhynchus mykiss)

Initial numbers of bacteria associated with wild (brown trout and pike) and cultured (rainbow trout) freshwater fish as well as with the water in which they were caught were determined. Subsequently, a total of 979 randomly selected isolates were characterized and identified to the genus level. For all counts performed (aerobes, psychrotrophs, anaerobes, Enterobacteriaceae, and enterococci), no significant differences were observed in water samples, the highest level corresponding to psychrotrophs in pike environments (4.23 X 10(3) CFU/ml). Overall, the skin and intestinal content of brown trout were the most contaminated, while rainbow trout specimens (gills and gut) yielded the lowest numbers. For all bacterial groups, pike gills had the highest numbers. Counts for all of the sampling sites compare well with findings in other temperate geographical environments. Biological characteristics (feeding and skin properties) and the use of antimicrobials in aquaculture might have influenced these results. Motile and nonmotile aerobic gram-negative bacteria together with Enterobacteriaceae accounted for 50 to 70% of the psychrotrophs isolated from water. Micrococcaceae, lactic acid bacteria, Bacillus, and coryneforms were also found. The groups represented in psychrotrophic isolates from the outer surfaces do not reflected those detected in water, so it was common that those organisms recovered in significant numbers from fish were not detected in surrounding habitat of the fish. Motile aeromonads and Carnobacterium were the dominant psychrotrophs in the guts of pike and brown trout, respectively. The intestinal content of reared fish gave a high incidence of Bacillus and coryneforms, while Enterobacteriaceae was absent. Again, rearing practices could have influenced this finding. Listeria monocytogenes was not detected in any of the examined samples. Two strains of Salmonella, which belonged to the same serovar and lysotype, were recovered from pond-water samples taken from one facility on different sampling days. From the gut of a pike specimen and from the pike's environment, two Plesiomonas shigelloides strains of different serovars were recovered. These latter four strains were resistant to a considerable number of antimicrobial compounds (multiple antibiotic resistance indices > 0.2).

In vitro inhibition of the replication of haemorrhagic septicaemia virus (VHSV) and African swine fever virus (ASFV) by extracts from marine microalgae

We have screened for in vitro inhibition of viral replication with extracts from the following marine microalgae: Porphyridium cruentum, Phaeodactylum tricornutum, Tetraselmis suecica, Chlorella autotrophica, Dunaliella tertiolecta, Dunaliella bardawil, Isochrysis galbana, Isochrysis galbana var Tiso, Ellipsoidon sp. and Tetraselmis tetrathele. We have used as viral models two enveloped viruses of significant economic importance, the viral hemorrhagic septicemia virus (VHSV) of salmonid fish and the African swine fever virus (ASFV). The aqueous extracts from P. cruentum, C. autotrophica and Ellipsoidon sp., produced a significant inhibition of the in vitro replication of both viruses in a dose-dependent manner. That this inhibition could be due to sulfated polysaccharides was suggested because the same pattern of viral inhibition was obtained by using exocellular extracts from microalgae enriched in these compounds and/or dextran sulfate of high molecular weight. However, the inhibition of viral replication did not correlate with the percentage of sulfatation of the exocellular polysaccharides. Extracts from marine microalgae may have prophylactic utility against fish and mammalian viral diseases.

Numbers and species of motile aeromonads during the manufacture of naturally contaminated Spanish fermented sausages (longaniza and chorizo)

The prevalence of aeromonads in the initial mixes of 14 batches of chorizo and longaniza obtained from three small- and middle-sized factories was 78.5%, with counts ranging from >1.00 to 4.47 log10 CFU/g. Only 2 of 10 mixture samples prepared at a large and modern processing plant yielded these organisms, with levels below 1 log10 CFU/g. The hygienic status of factories significantly affected incidence and counts. Of 39 presumptive isolates from glutamate starch penicillin agar, 36 were confirmed as motile aeromonads and allocated to Aeromonas hydrophila (n = 24), A. veronii biovar sobria (n = 10), and A. caviae (n = 2). All of them were beta-hemolytic and capable of growing at 5 degrees C. Regardless of initial contamination, aeromonads were rapidly inactivated during the early stages of manufacture.

Modeling of air pollution and its relationship with mortality and morbidity in Madrid, Spain

OBJECTIVE

Evaluation of the association between air pollution and mortality and morbidity is becoming ever more complex owing to changes in inner-city air pollution, marked by decreasing values for all main pollutants save those associated with traffic. This has led to the need for the study of new epidemiological scenarios in which most pollutants are below guideline values. Nonetheless, the health effects are significant.

METHODS

This report presents the results of a statistically based model for real-time forecasting of mortality and morbidity in Madrid, with meteorological and pollution series serving as inputs.

RESULTS AND CONCLUSIONS

Not only did the models perform well with correlation coefficients between predicted and observed values (r = 0.683 for mortality, r = 0.681 for morbidity), but they enabled quantification of the impact of air pollution on mortality and morbidity (with increases ranging from 1. 8% to 12% for mortality and from 2.3% to 18% for morbidity for a 25-microg/m(3) increase in pollutants). Moreover, attention should be drawn to the observation that the model proved to be easy to implement and operate on a routine basis.

Antigenic and genetic characterization of twenty-six strains of human respiratory syncytial virus (subgroup A) isolated during three consecutive outbreaks in Havana city, Cuba

Twenty-six human respiratory syncytial virus strains (subgroup A) isolated from three outbreaks in Havana City during the period 1994/95, 1995/96 and 1996/97 were analyzed to determine their antigenic and genetic relationships. Analyses were performed by monoclonal antibodies and restriction mapping (N gene) following amplification of the select region of the virus genome by polymerase chain reaction. All isolated strains were classified as subgroup A by monoclonal antibodies and they showed a restriction pattern NP4 that belonged to subgroup A. Thus the results obtained in this work, showed a close relation (100%) between antigenic and genetic characterization of the isolated strains in our laboratory. These methods permit the examination of large numbers of isolates by molecular techniques, simplifying the researchs into the molecular epidemiology of the virus.

Behaviour of Listeria spp. in naturally contaminated chorizo (Spanish fermented sausage)

Counts of Listeria spp. were determined during the manufacture and drying of 21 lots of five chorizo varieties produced by three different manufacturers. Presumptive Listeria were not isolated from any of the batches produced in a large factory (F3) using starter, sorbate and controlled ripening at high temperatures. Initial levels in factory 1 (F1), with no starter added, but controlled ripening at low temperatures, were ca 3.5 log10 cfu/g while those in factory 2 (F2), with no starter added and ripening under natural climatic conditions, were 1.17 log10 cfu/g. Numbers of listeriae in batches obtained from F1 remained almost constant before decreasing by ca 0.5 log units/g in the finished product (32 days), while the levels in F2 increased by 1.47 log units/g after 11 days of ripening and declined further to levels above the original amount. Manufacturing procedure and smoking significantly affected presumptive listeriae counts. Thirteen strains recovered from F1 batches were identified as: Listeria monocytogenes (three strains of serovar 1/2c), Listeria innocua (eight strains of serovar 6b) and Listeria welshimeri (two strains of serovar 6b). Listeria strains from F2 were assigned to L. innocua and L. welshimeri.

[The use of ELISA and ultramicro ELISA in identifying a Coxsackie A9 strain isolated during the epidemic of neuropathy in Cuba]

During 1993 an outbreak of epidemic neuropathy characterized by 2 major clinical forms: the optic neuropathy and peripheral neuropathy, occurred in our country. Although the cause of the disease was considered to be multifactorial (mainly due to neurotoxic agents and to nutritional deficiency) an Enterovirus was isolated from the cerebrospinal fluid of a patient (strain 47/93, IPK) which was subsequently classified as a Coxsackie A9 virus (Cox A9) by the neutralization test, and using pools of Lim Benyesh Melnick (LBM) serum. Results obtained during the application of ELISA and ultramicro ELISA techniques for the identification of this agent from the supernatant of a culture of infected cells are reported, as well as the detection of antibodies to the strain found within populations with high and low incidence rates of the disease.

[An immunoenzyme assay for the detection of monoclonal antibodies against the E and NS1 proteins of the dengue virus]

The ELISA was standardized to detect monoclonal antibodies of dengue virus proteins E and NS1. One indirect ELISA was applied, using C6-36 cells inoculated with the A-15 strain, isolated during the dengue 2 epidemic in 1981 as an antigen source. These cells were fixed in ELISA plates at a 200,000 cell/well concentration. A cell control in similar conditions was used. Specific monoclonal antibodies to both proteins were used to standardize the system. Studies at different incubation periods, to determine the highest expression moment of these proteins in the cell membrane, were carried out. The results show a full response at 72 hours postinoculation for both proteins; a 14.7 ng/mL sensitivity was obtained for the detection of NS1, and of 1.43 ng/mL for E protein. This system allows the monoclonal antibodies primary screening to dengue 2 virus E and NS1 proteins.

[Estimation of IgG Adenovirus antibody titers using a standard curve and an indirect ultramicroELISA essay]

It was possible to standardize a procedure which combined an indirect microELISA assay with a standard curve and that allowed to estimate the titre of IgG antibodies to Adenovirus in samples of human serum, using only one dilution of these. Based on the end-point titre previously determined for a panel of 117 serum samples, we selected 90 of these samples (r2 = 0.98) to build 4 standard curves that related the natural logarithm of the fluorescence responses to the natural logarithm of the end-point titre for a wide range of serum dilutions (1:40 = 1:320). It was selected the curve corresponding to serum dilution 1:40 (r2 = 0.81), which made possible an optimum utilization of those accessories designed to handle the volumes in the ultramicro range and, therefore, the automation of the whole procedure. The results obtained as regards the complement fixation test (100% of sensitivity and 97.3% of specificity) support the use of this method in our laboratory as a complementary tool to carry out seroepidemiological studies on a large scale and with diagnostic ends.

[Serologic diagnosis of HIV (1988-1989)]

Determination of antibodies to HIV virus by the ELISA technique was performed in 27,652 serum samples from January 1988 to November 1989. Samples which were positive twice underwent the Western Blot technique. A 0.41% of positiveness to the virus was found in 1988 and a 0.34% in 1989. Confirmation of positive cases by Western Blot was statistically significant in 1989.

[Restenosis and remodeling after percutaneous transluminal carotid angioplasty]

INTRODUCTION

The characteristics of restenosis and remodeling after carotid percutaneous transluminal angioplasty (PTA) were badly known.

OBJECTIVE

To describe these characteristics in our series of carotid PTA.

PATIENTS AND METHODS

A total of 78 cases of PTA for symptomatic > 70% atherosclerotic stenosis of the extracranial internal carotid artery, were selected from our series of PTA if follow-up was > 12 months. All of them were followed with extracranial continuous-wave Doppler.

RESULTS

Restenosis of any degree was found in 17 cases (21.79%) and always asymptomatic. A restenosis > or = 70% was found in 5 cases (6.4%). Restenosis was mainly found in cases without residual stenosis nor dissection after PTA (p = 0.002). Restenosis was found in 16 cases (94.11%) in the first 6-months, with no progression thereafter. Remodeling of residual stenosis was frequent (17 cases; 53.11%) and found mainly during the first month after PTA. Its incidence was highest in patients with dissection treated with heparin. In cases with restenosis, remodeling was infrequent, incomplete and occurred after 18-24 months.

CONCLUSIONS

1. Significant restenosis after PTA due to myointimal proliferation, was infrequent. All cases were asymptomatic, under antiplatelet treatment. A new interventional procedure might not be necessary. 2. Complete remodeling was frequently found after 1-month control, mainly in arteries with some residual stenosis and dissection after PTA.

[Evaluation of a mouse anti-IgG-fluorescein conjugate using indirect immunofluorescence and flow cytometry techniques]

An immunoglobulin G of mouse was purified from sera by affinity chromatography in protein A. The rabbits whose sera were able to recognize the antigen injected by double immunodiffusion were immunized with this preparation. The antibodies were precipitated from the rabbit's serum and purified by ion exchange chromatography. This preparation was conjugated to fluorescin isothiocyanate according to the conventional technique. The conjugated obtained was evaluated with the reference strains of Parainfluenza virus 1, 2, 3; Adenovirus; respiratory syncytial virus; and influenza virus A and B, by an indirect immunofluorescence technique and HIV positive samples by flow citometry. Specific monoclonal antibodies were used in both cases. Clinical specimens of patients with acute respiratory infection were evaluated.

Rapid microbiological methods in meat and meat products

Modern analytical techniques have to provide accurate results in time to permit forward approaches for controlling the microbiological quality of foods. Although the classical microbiological procedures of counting and identification of micro-organisms have been automated, several techniques with quite different principles are now used. The quantification of the microbial load of meat samples can be done in 4-24 hr with methods involving the growth of micro-organisms in liquid media (impedance and turbidimetric methods) and in less than 2 hr with methods counting stained microbial cells or detecting components of microbial cells. Rapid detection of undesirable (pathogens or spoilers) micro-organisms in meat samples can be done with immunological and DNA-based methods. The main techniques which can be used for the microbiological quantification and identification in the meat industries, as well as their applications are reviewed. Possibilities for rapid typing of bacterial isolates are also presented. Finally, some future trends in the microbiological analysis of foods are discussed.