The hamster cheek pouch: an immunologically privileged site suitable to the study of granulomatous infections

The hamster check pouch is an invagination of oral mucosa, characterized histologically as skin-like. In this paper we describe anatomical, histological and embriological features of the pouch and coment on the pouch as an immunologically privileged site since it lacks lymphatic drainage and has few Langerhans cells. We present the review from literature and our observations after inoculation in the pouch of mycobacteriae (BCG, Mycobacterium tuberculosis and Mycobacterium leprae) and a fungus (Paracoccidioides brasiliensis). Lesions in the pouch were granulomatous but smaller and long lasting; even granulomatous, the reaction was inefficient to control the proliferation of agents compared with inoculation in other sites, except for BCG. Appearance of immunity was also delayed or absent and, when it was detected, a sharp decrease in number of agents in pouch lesions was observed. These observations make the pouch an interesting site for the study of the role of immune system in infeccious diseases and in granuloma formation.

Fungal infections in neutropenic patients: a 8-year prospective study

In this paper we report a eight-year prospective study designed to further characterize incidence, epidemiology, specific syndromes, treatment and prognosis associated with fungal infections in neutropenic patients. During the study period 30 fungal infections were diagnosed in 30 patients among 313 episodes of fever and neutropenia (10%). There were 15 cases of candidiasis, 5 pulmonary aspergillosis, 3 sinusitis by Aspergillus fumigatus, 5 infections by Fusarium sp., one infection by Trichosporon sp., and one infection due to Rhodotorula rubra. Blood cultures were positive in 18 cases (60%). The predisposing factors for fungal infection in multivariate analysis were the presence of central venous catheter (p<0.001), longer duration of profound (<100/mm³) neutropenia (p<0.001), the use of corticosteroids (p<0.001), gram-positive bacteremia (p=0.002) and younger age (p=0.03). In multivariate analysis only recovery of the neutropenia (p<0.001) was associated with good prognosis whereas the diagnosis of infection by Fusarium sp. (p=0.006) was strongly associated with a poor outcome. The death rate was 43%. There was no statistically significant difference in the death rate between patients who did receive (52%) or did not receive (50%) antifungal treatment. Identifying patients at risk, specific syndromes and prognostic factors may help to reduce the high mortality associated with disseminated fungal infections in neutropenic patients.

The relevance of laboratory diagnosis of human cryptosporidiosis and other coccidia

Human infection by Cryptosporidium spp and other coccidia are due to opportunist non-host specific microorganisms. In HIV seropositive patients, the gastrointestinal symptoms accompanying such infections may be serious and prolonged and may include nausea, low-grade fever, abdominal cramps, anorexia and watery diarrhoea. We studied 188 stool samples from 111 patients (84 men and 27 women) with diarrhoea. A modified Ziehl-Nielsen technique for the detection of Cryptosporidium spp and Isospora belli was employed. The mean age of the patients was 31 years. Cryptosporidium spp was seen in 18% (n=20) of the patients, 90% (n=18) of whom were HIV seropositive. Isospora belli was recorded only from HIV seropositive patients (5.4% of all the patients studied and 6.5% of those who were HIV seropositive). These data confirm the good results obtained with this technique for the identification of Cryptosporidium spp and other coccidia and also reaffirm the clinical importance of correctly diagnosing the cause of diarrhoea, particularly in HIV seropositive patients.

Cross-reactivity of antibodies in human infections by the kinetoplastid protozoa Trypanosoma cruzi, Leishmania chagasi and Leishmania (Viannia) braziliensis

We have detected antibodies, in the sera of Chagas disease, Kala-azar and Mucocutaneous leishmaniasis patients, that bind multiple antigens shared between the three causative agents. The Chagas disease sera showed 98 to 100% positive results by ELISA when the Leishmania braziliensis and Leishmania chagasi antigens were used, respectively. The Kala-azar sera showed 100% positive results with Trypanosoma cruzi or L. braziliensis antigens by immunofluorescence assays. The antibodies in the sera of Mucocutaneous leishmaniasis patients showed 100% positive results by ELISA assays with T. cruzi or L. chagasi antigens. Furthermore, the direct agglutination of L. chagasi promastigotes showed that 95% of Kala-azar and 35% of Mucocutaneous leishmaniasis sera agglutinated the parasite in dilutions above 1:512. In contrast, 15% of Chagas sera agglutinated the parasite in dilutions 1:16 and below. Western blot analysis showed that the Chagas sera that formed at least 24 bands with the T. cruzi also formed 13 bands with the L. chagasi and 17 bands with the L. braziliensis. The Kala-azar sera that recognized at least 29 bands with the homologous antigen also formed 14 bands with the T. cruzi and 10 bands with the L. braziliensis antigens. Finally, the Mucocutaneous leishmaniasis sera that formed at least 17 bands with the homologous antigen also formed 10 bands with the T. cruzi and four bands with the L. chagasi antigens. These results indicate the presence of common antigenic determinants in several protozoal proteins and, therefore, explain the serologic cross-reactions reported here.

Gastrointestinal translocation as a possible source of candidemia in an AIDS patient

Apart from cryptococcosis and histoplasmosis, which are mycoses contained by T cell-mediated mechanisms of host defense, fungemia is rarely found in AIDS patients. The frequency of fungemia due to Candida spp. has been reported to be as low as 1 %. We report a non-neutropenic AIDS patient who presented a candidemia which probably arose from her gastrointestinal tract.

Concomitant rotavirus serotypes 1 and 4 infections in a diarrhoeic child from Belém, Brazil

Concomitant serotypes 1 and 4 infections were detected in a 15-month old female child with community-acquired diarrhoea which lasted 7 days and coursed with moderate dehydration. The evidence for dual rotavirus infection was offered by the following findings: a) enzyme-linked immunosorbent assay (ELISA) positive reactions to both 1 and 4 serotypes; and b) extra-migrating bands at electro-phoresis of RNA in polyacrylamide gel (PAGE). These results suggest that children living under poor sanitation conditions are heavily exposed to rotavirus infections; in addition, the co-circulation of different serotypes in the same setting sustains the current concept that a rotavirus vaccine should be rnultivalent, in order to protect children against the four epidemiologically important rotavirus G serotypes.

Prevalence of HTLV-I and HTLV-II infections among HIV-1-infected asymptomatic individuals in São Paulo, Brazil

Human immunodeficiency virus (HIV-1)-infected subjects with acquired immunodeficiency syndrome (AIDS) are often infected with multiple pathogens. In particular, HTLV-I and HTLV-II infections have been found more frequently in AIDS patients than in asymptomatic individuals in Europe and Japan. We carried out a serosurvey among asymptomatic HIV-1-infected subjects in São Paulo, Brazil and compared our results with those of other investigators. In this study, we found HTLV infection in 1.5% of 266 asymptomatic and 14% of 28 AIDS patients. Epidemiological data obtained from patients pointed out the use of intravenous drugs as the principal risk factor for acquiring retroviruses. In conclusion, our results are in accordance with other studies done in Brazil and elsewhere where the principal risk group for HIV/HTLV-I/II coinfection was IDU

Evolution of IgG antibody response against Toxoplasma gondii tissue cyst in acute and chronic human infections

The recognition profile of the tissue cysts antigens by IgG antibodies was studied during acute and chronic human toxoplasmic infection. Thus the IgG response against Toxoplasma gondii was investigated by immunoblotting in two patients accidentally infected with the RH strain as well as in group of naturally infected patients at acute and chronic phase. There was an overall coincidence of molecular mass among antigens of tachyzoites and tissue cysts recognized by these sera, however, they appear not to be the same molecules. The response against tissue cysts starts early during acute infection, and the reactivity of antibodies is strong against a wide range of antigens. Six bands (between 82 and 151 kDa) were exclusively recognized by chronic phase sera but only the 132 kDa band was positive in more than 50% of the sera analysed. A mixture of these antigens could be used to discriminate between the two infection phases. The most important antigens recognized by the acute and the chronic phase sera were 4 clusters in the ranges 20-24 kDa, 34-39 kDa, 58-80 kDa and 105-130 kDa as well as two additional antigens of 18 and 29 kDa. Both accidentally infected patients and some of the naturally infected patients showed a weak specific response against tissue cyst antigens.

ENTEROVIRUSES ISOLATED FROM PATIENTS WITH ACUTE RESPIRATORY INFECTIONS DURING SEVEN YEARS IN RIO DE JANEIRO (1985-1991)

Enteroviruses were investigated in respiratory secretions collected from patients with acute respiratory infections (ARI) over a seven year period (1985-1991), as part of a longitudinal study of ARI aetiology. All the viruses that are most commonly associated with ARI were found in this study. Among the virus isolates, enteroviruses were only less frequent than respiratory syncytial viruses, adenoviruses and influenzaviruses. Forty five enterovirus samples were isolated from patients with either upper respiratory tract infections (URTI) or lower respiratory tract infections (LRTI). From these enterovirus isolates, thirty one samples were identified as poliovirus (n=18) and non polio enterovirus (n=13) by serum neutralization. Poliovirus were identified as type 1 and 2 and all of them were vaccinal strains. From thirteen non polio enterovirus, twelve were identified as echovirus serotypes 1, 2, 7, 11, 19 and 31. The remainder was identified as coxsackievirus B4.

Chronic hepatitis C virus infections in Brazilian patients: association with genotypes, clinical parameters and response to long term alpha interferon therapy

The present study assessed the clinical significance of hepatitis C virus (HCV) genotypes and their influence on response to long term recombinant-interferon-alpha (r-IFN-a) therapy in Brazilian patients. One hundred and thirty samples from patients previously genotyped for the HCV and with histologically confirmed chronic hepatitis C (CH-C) were evaluated for clinical and epidemiological parameters (sex, age, time of HCV infection and transmission routes). No difference in disease activity, sex, age or mode and time of transmission were seen among patients infected with HCV types 1, 2 or 3. One hundred and thirteen of them were treated with 3 million units of r-IFN-a, 3 times a week for 12 months. Initial response (IR) was significantly better in patients with genotype 2 (100%) and 3 (46%) infections than in patients with genotype 1 (29%) (p < 0.005). Among subtypes, difference in IR was observed between 1b and 2 (p < 0.005), and between 1b and 3a (p < 0.05). Sustained response (SR) was observed in 12% for (sub)type 1a, 13% for 1b, 19% for 3a, and 40% for type 2; significant differences were found between 1b and 2 (p < 0.001), and between 1b and 3a (p < 0.05). Moreover, presence of cirrhosis was significantly associated with non response and response with relapse (p < 0.05). In conclusion, non-1 HCV genotype and lack of histological diagnosis of cirrhosis were the only baseline features associated with sustained response to treatment. These data indicate that HCV genotyping may have prognostic relevance in the responsiveness to r-IFN-a therapy in Brazilian patients with chronic HCV infection, as seen in other reports worldwide.

Cryptic infections in mice with the Trypanosoma cruzi CL-14 clone

A infectividade do clone CL-14 do Trypanosoma cruzi para camundongos foi revista utilizando-se como inóculo metacíclicos de cultura em NNN+LIT, pré-incubados ou não com complemento de cobaio. Nos animais inoculados não observamos parasitemia patente, mas a presença do parasito foi confirmada em 30% deles (9/30) através de hemocultivo ou xenodiagnóstico, este examinado aos 100 dias. A positividade das hemoculturas pôde ser evidenciada a partir dos 60 dias quando procederam de camundongos inoculados com metacíclicos tratados com complemento. Nos demais hemocultivos a positividade foi constatada aos 100 dias ou posteriormente. Um reisolado do CL-14 também não determinou parasitemia patente em camundongos até 30 dias após a inoculação. Estes achados são discutidos em relação à proteção imunológica observada em camundongos inoculados com este clone.

Asymptomatic infections by diarrheagenic Escherichia coli in children from Misiones, Argentina, during the first twenty months of their lives

Diarrheagenics Escherichia coli are the major agents involved in diarrheal disease in developing countries. The aim of this study was to evaluate the time of appearance of the first asymptomatic infection by the different categories of diarrheagenic E. coli in 44 children since their birth and during the first 20 months of their lives. In all of the children studied, we detected at least one category of diarrheagenic E. coli through the 20 months of the study. 510 diarrheagenic E. coli (33.5%) were obtained from the 1,524 samples collected from the 44 children during the time of the study (31.4% EAggEC, 28.8% EPEC, 27.1% DAEC, and 12.7% ETEC). Neither EHEC nor EIEC were identified. The median age for diarrheagenic E. coli colonization was 7.5 months. The mean weaning period was 12.8 months and the mean age for introduction of mixed feeding (breast fed supplemented) was 3.8 months. A significantly lower incidence of diarrheal disease and asymptomatic infections was recorded among the exclusively breast-fed rather than in the supplemented and non breast-fed infants. For ETEC, EPEC and EAggEC the introduction of weaning foods and complete termination of breast-feeding were associated with an increase of asymptomatic infections.

Persistent infections in chronic Chagas' disease patients treated with anti-Trypanosoma cruzi nitroderivatives

We used a molecular method and demonstrated that treatment of the chronic human Trypanosoma cruzi infections with nitroderivatives did not lead to parasitological cure. Seventeen treated and 17 untreated chronic Chagas' disease patients, with at least two out of three positive serologic assays for the infection, and 17 control subjects formed the study groups. PCR assays with nested sets of T. cruzi DNA primers monitored the efficacy of treatment. The amplification products were hybridized to their complementary internal sequences. Untreated and treated Chagas' disease patients yielded PCR amplification products with T. cruzi nuclear DNA primers. Competitive PCR was conducted to determine the quantity of parasites in the blood and revealed < 1 to 75 T. cruzi/ml in untreated (means 25.83 ± 26.32) and < 1 to 36 T. cruzi/ml in treated (means 6.45 ± 9.28) Chagas' disease patients. The difference between the means was not statistically significant. These findings reveal a need for precise definition of the role of treatment of chronic Chagas' disease patients with nitrofuran and nitroimidazole compounds.