Severe SARS-CoV-2 pneumonia: Clinical, functional and imaging outcomes at 4 months.

INTRODUCTION: Given the pathophysiology of coronavirus disease 19 (COVID-19), persistent pulmonary abnormalities are likely. METHODS: We conducted a prospective cohort study in severe COVID-19 patients who had oxygen saturation<94% and were primarily admitted to hospital. We aimed to describe persistent gas exchange abnormalities at 4 months, defined as decreased diffusing capacity of the lungs for carbon monoxide (DLco) and/or desaturation on the 6-minute walk test (6MWT), along with associated mechanisms and risk factors. RESULTS: Of the 72 patients included, 76.1% required admission to an intensive care unit (ICU), while 68.5% required invasive mechanical ventilation (MV). A total of 39.1% developed venous thromboembolism (VTE). After 4 months, 61.4% were still symptomatic. Functionally, 39.1% had abnormal carbon monoxide test results and/or desaturation on 6MWT; high-flow oxygen, MV, and VTE during the acute phase were significantly associated. Restrictive lung disease was observed in 23.6% of cases, obstructive lung disease in 16.7%, and respiratory muscle dysfunction in 18.1%. A severe initial presentation with admission to ICU (P=0.0181), and VTE occurrence during the acute phase (P=0.0089) were associated with these abnormalities. 41% had interstitial lung disease in computed tomography (CT) of the chest. Four patients (5.5%) displayed residual defects on lung scintigraphy, only one of whom had developed VTE during the acute phase (5.5%). The main functional respiratory abnormality (31.9%) was reduced capillary volume (Vc<70%). CONCLUSION: Among patients with severe COVID-19 pneumonia who were admitted to hospital, 61% were still symptomatic, 39% of patients had persistent functional abnormalities and 41% radiological abnormalities after 4 months. Embolic sequelae were rare but the main functional respiratory abnormality was reduced capillary volume. A respiratory check-up after severe COVID-19 pneumonia may be relevant to improve future management of these patients.

[The need for the use of chromogens for quantifying Leishmania promastigotes on plates from 96 wells]. / Necesidad del uso de cromógenos para cuantificar promastigotes de Leishmania en placas de 96 pozos.

The existing difficulties in the treatment of leishmaniasis justify the testing of the effect of new products on parasite forms in the search of a therapeutic alternative for the parasitosis. Given the need of establishing a method to evaluate the activity of natural synthetic products in vitro under the Cuban conditions, this paper was aimed at defining the usefulness of p-nitrophenilphosphate as a chromogenic substance for quantification of parasites in plaques from 96 wells. To standardize this colorimetric method the stages of the parasite growth curve were set. The study of linearity and selection of the sample size, which was optional for these assays, showed that it was possible to obtain maximum linear determination coefficient with 20 mm. Likewise, the variation coefficient was compared with and without the chromogen and the effect of changes in culture medium on the reading of absorbances was analyzed. The set limit of quantification proved the need of using chromogen for the purposes of this paper and the general results allow to recommend this less subjective, simpler and quicker methodology to test products of interest in this field.

The hyperferremic mouse model for the evaluation of the effectiveness of VA-MENGOC-BC against Neisseria meningitidis B clinical isolates.

VA-MENGOC-BC is a vaccine against B and C serogroups of Neisseria meningitidis. Its effectiveness at population level has been shown after the application of the vaccine in Cuba, Brazil, Argentina and Colombia. In vitro assays are not always able to reproduce the microorganism-host relationships and this makes it necessary to compile and standardize results obtained in animal models to extrapolate them with a greater degree of safety for humans. We evaluated the effectiveness of VA-MENGOC-BC against Neisseria meningitidis group B isolates from clinically ill patients in Latin America (Argentina, B not typeable: P1; Chile, not typed; Colombia, B4:P1.15 and Cuba B4:P1.15) using Balb/cJ mice treated with iron to make them susceptible to Neisseria meningitidis. The lethal median dose of each strain and of two others that were not included in challenge assays (Brazil: P1.15 and Argentina, B2b:P1.10) were determined. Results were 2.68 x 10(6), 3.16 x 10(7), 1.98 x 10(8), 1.28 x 10(9), 6.42 x 10(6) and 3.88 x 10(7) colony forming units (CFU), respectively. Non-immunized animals and mice treated with one and two doses of VA-MENGOC-BC were challenged with 10(3)-(10) CFU. Protection ranged from 30 to 100% with one dose and was equal to or higher than 70% with the two-dose immunization schedule. A significant protection could not be observed against the Colombian isolate from the lethality point of view, but the mean time of survival lengthened in immunized animals in relation to the controls. The applied inoculum of this strain was much higher (505 x LD50) than the remaining ones. The protection conferred was evident; nevertheless, more data are needed to determine how relevant the results are to humans.

Experimental infection by Haemophilus influenzae type b in inbred mice.

The epidemiological situation of bacterial meningitis is increasing dramatically. There is no doubt that the lack of proper animal models has hampered the achievement of effective prophylactic and therapeutic means. We report the characterization of the experimental disease caused by Haemophilus influenzae type b (Hib) in mice, taking into account its importance as an etiological agent of such a type of meningitis. The high resistance of C57BL/6, CBA/ J and BALB/cJ mice to Hib infection was proven. LD50 of Hib using trypsin or iron dextran as virulence enhancement factors (VEF), both being similar and more than 1000 times lower than that without any VEF, were determined. Lesions of CNS compatible with meningitis were found in about one third of specimens. Hair bristling, conjunctivitis, diarrhea, depression and prostration were the most characteristic symptoms. The proportion of animals which die is highest on the first day, lower on the second and almost zero after 48 h of infection. Water and food intake was higher in control than in infected animals; nevertheless, there were no differences in body weight increase among the mice after 5 days post-infection. Microorganisms were isolated from CSF and blood after 6 h of infection and positive results remained according to the size of the inoculum. Despite the acuteness of the experimental disease, antibiotic treatment with internationally recommended drugs was shown to be effective. Similar results were achieved when hyperimmune serum vs. Hib was applied.

Pathologic-clinical characterization of leptospirosis in a golden Syrian hamster model.

Experimental leptospirosis was reproduced in golden Syrian hamsters (Mesocricetus aureatus). Evaluation of three Leptospira serogroups (canicola, icterohaemorrhagiae and pomona) was carried out regarding their virulence, production of symptoms and lethal activity. Macroscopic and microscopic studies of tissue lesions were also made. Animals were inoculated with 3.75 x 10(6) to 6 x 10(7) bacteria through the intraperitoneal (IP) route. The clinical development of the disease in Syrian hamsters was characterized by the presence of general symptoms between the third and fifth day after inoculation. With highly virulent strains, the distinctive clinical picture occurred and death followed before the seventh day. The strain of the pomona serogroup proved to be more virulent than those of the other serogroups and produced the most florid picture of the disease. Pathogenic aspects of this process were also studied.

Evaluation of the efficacy of human antimeningococcal immunoglobulin G in infant rats experimentally infected with Neisseria meningitidis group B.

Infants rats, a well known model for the experimental reproduction of bacterial meningitis, were used by us to test the protective potential of antibodies developed in humans who had been vaccinated with the Cuban antimeningitis vaccine (VA-MENGOCBC). Newborn rats were inoculated by the intraperitoneal and intranasal routes with suspensions of Neisseria meningitidis group B bacteria. Bacteremia kinetics were evaluated from blood and brain-spinal fluid cultures. Samples of the central nervous system were taken and smears of backbone fluids prepared for histopathologic evaluations. Characterization of bacteremia evolution, as well as the mean lethal dose of germs and histopathologic features, were determined. After standardization of the model, therapeutic schemes were applied using passive immunization pre- and post-infection with N. meningitidis. A significant level of protection was obtained in relation to control animals that received the same challenge doses.