Biomedical subjects
G A da Silva
Publications and source records attributed to G A da Silva.
The occurrence of killer, sensitive, and neutral yeasts in Brazilian Riesling Italico grape must and the effect of neutral strains on killing behaviour.
The occurrence of killer toxins amongst yeast in Brazilian Riesling Italico grape must was investigated by using the sensitive strain EMBRAPA-26B as a reference strain at 18 degrees C and 28 degrees C. From a total of 85 previously isolated yeasts, 21 strains showed ability to kill the sensitive strain on unbuffered grape must/agar (MA-MB) and 0.1 M citrate/phosphate-buffered yeast extract/peptone/dextrose/agar (YEPD-MB) media both supplemented with 30 mg/l methylene blue. The killer activity of only four yeasts depended on the incubation temperature rather than the medium used. At 28 degrees C, the strains 11B and 53B were not able to show killer action. On the other hand, strains 49B and 84B did not kill the sensitive yeast at 18 degrees C. The killer strain EMBRAPA-91B and a commercial wine killer yeast K-1 were employed to examine the sensitivity of the isolated yeasts on YEPD-MB and MA-MB at 18 degrees C. The sensitivity and neutral characteristics of yeasts were shown to be dependent on the medium and the killer strain. Interactions, including K-R-, K-R+ and K+R+ strains, simultaneously, have revealed that some K-R+ strains appear to protect the K-R- strain against the killer toxin. Sensitive dead cells, although to a less extent, also exhibited similar protection. Kinetic studies have shown that the maximum specific growth rates were higher for the 20B YEPD-MB-sensitive strains (mu(max) = 0.517 h-1) than for both the 91B (mu(max) = 0.428 h-1) and K-1 (mu(max) = 0.466 h-1) killer strains. The protective capacity of neutral or sensitive cells that contaminate a fermentation, as well as the higher maximum specific growth rate of sensitive yeasts, besides other factors, may preclude the dominance of a killer strain. This protective capacity may also reduce the risk of a sensitive inoculum being killed by wild-type killer yeasts in open non-sterile fermentation.
Seroprevalence of HIV-1 among pregnant women at Recife, northeastern Brazil.
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A study of the importance of the enterotoxigenic E. coli in children with acute diarrhoea in Recife, Brazil.
Even today acute diarrhoea is a major cause of morbidity and mortality in young children. It is a serious public health problem in less-developed countries, primarily in households whose income is low. As such, it is one of the main causes of death, affecting the undernourished in particular. The potential enteropathogenic agents are distributed universally. However, there is a major difference in the prevalence, according to the areas and the characteristics of the population groups which were studied. In Brazil, since the 1970s, our attention has been drawn to the importance of the classic enteropathogenic strains of E. coli (EPEC) in the aetiology of diarrhoeal diseases, primarily those present in weaned infants in inner city neighbourhoods. On the other hand, Guerrant and co-workers, and Queiroz and co-workers found significant percentages of isolated colonies of enterotoxigenic coli (ETEC) in the stool material of children with symptoms of acute diarrhoea. In rural areas of less-developed countries the incidence of episodes of ETEC provoking diarrhoea is estimated to be between five and ten per person/year. Due to the social and medical gravity of acute diarrhoea, and to the lack of studies dealing with the aetiopathogenic role of the strains of ETEC in our area, we decided to analyse the frequency of isolation of ETEC in children with and without diarrhoea who were attending the out-patient department of the Instituto Materno Infantil de Pernambuco/IMIP.
Comparative efficacy of oral rifampin and topical chloramphenicol in eradicating conjunctival carriage of Haemophilus influenzae biogroup aegyptius. Brazilian Purpuric Fever Study Group.
Persistent conjunctival carriage of the Haemophilus influenzae biogroup aegyptius (Hae) strain (BPF clone) responsible for Brazilian purpuric fever (BPF) has been documented. Topical chloramphenicol is routinely used to treat conjunctivitis in areas affected by BPF in Brazil. Although the BPF clone is susceptible to chloramphenicol, we observed a number of children treated with topical chloramphenicol for conjunctivitis who still developed BPF. During an investigation of an outbreak of BPF in Mato Grosso State, Brazil, we compared oral rifampin (20 mg/kg/day for 4 days) with topical chloramphenicol for eradication of conjunctival carriage of H. influenzae biogroup aegyptius among children with presumed BPF clone conjunctivitis. Conjunctival samples were taken for culture on the day treatment was initiated and a mean of 8 and 21 days later. At 8 days the eradication rates for oral rifampin and topical chloramphenicol were 100 and 44%, respectively (P = 0.003); at 21 days they were 100 and 50% (P = 0.01). Oral rifampin was more effective than topical chloramphenicol for eradication of the BPF clone and may be useful in prevention of BPF.
Epidemiology and clinical spectrum of Brazilian purpuric fever. Brazilian Purpuric Fever Study Group.
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Brazilian purpuric fever: an epidemiologic and clinical summary. The Brazilian Purpuric Fever Study Group.
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Coryneform bacteria in poultry, eggs and meat.
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Numerical taxonomy of certain coryneform bacteria.
da Silva, G. A. Nigel (Iowa State University, Ames), and John G. Holt. Numerical taxonomy of certain coryneform bacteria. J. Bacteriol. 90:921-927. 1965-An electronic computer was used to sort 32 strains of coryneforms into groups with the tree-sort program. The similarity values obtained in this procedure were then used to construct a dendrogram depicting the phenetic resemblance among the taxa. The results indicated that all the phytopathogens studied were sufficiently distinct from the type species, Corynebacterium diphtheriae, to be excluded from the genus Corynebacterium. The grouping of some of the phytopathogens with Microbacterium lacticum is discussed. C. fascians appeared so distinct from the other strains studied that it should probably be excluded from the Corynebacteriaceae. The phenetic resemblance of Brevibacterium linens and Arthrobacter globiformis was emphasized, and the new combination, Arthrobacter linens, was proposed. In addition, because of distinct dissimilarity from the type species, it would seem desirable to exclude Arthrobacter tumescens from the genus Arthrobacter. The justification for classifying Kurthia zopfii in a family separate from the Corynebacteriaceae would appear to be open to serious question. It was concluded that the present taxonomic positions of Listeria monocytogenes, Cellulomonas biazotea, and Cellulomonas fimi are satisfactory.
[Does the use of pacifiers lead to a greater ocurrence of intestinal parasites?].
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[Acute infant diarrhea associated to Cryptosporidium sp., in the city of Recife].
From February through June 1990 the frequency of Cryptosporidium sp. among 156 infants with acute diarrhea and 80 controls were analyzed. The study was carried out in the Hospital Geral de Pediatria do Instituto Materno-Infantil de Pernambuco. Cryptosporidium sp. was detected in 6.4% of infants with diarrhea; it was not found in the controls. The clinical patterns and the disease evolution were the same in the infants Cryptosporidium-positive and Cryptosporidium-negative.