Effect of inulin on growth and acidification performance of different probiotic bacteria in co-cultures and mixed culture with Streptococcus thermophilus

Inulin was used as a prebiotic to improve the quality and consistency of skim milk fermented by Lactobacillus acidophilus (La), Lactobacillus rhamnosus (Lr), Lactobacillus bulgaricus (Lb) and Bifidobacterium lactis (BI) with Streptococcus thermophilus (St), either in binary co-cultures or in cocktail containing all microorganisms. We compared, either in the presence of 40 mg inulin g(-1) or not, the results of the maximum acidification rate (V(max)) and the times to reach it (t(max)), to reach pH 5.0 (t(PH5.0)) and to complete the fermentation (t(f)). Post-acidification, lactic acid formation and cell counts were also compared after either 1 day (D1) or 7 days of storage at 4 degrees C (N). In co-culture, inulin addition to the milk increased V(max), decreased t(max) and t(f), favored post-acidification and exerted a bifidogenic effect. S. thermophilus proved to stimulate the metabolism of the other lactic bacteria and enhanced the product features. After D7, a significant prebiotic effect of inulin was observed in all co-cultures. Either after D1 or D7, the enumerations of Lr and BI in mixed culture markedly decreased compared to their respective co-cultures because of greater competition for the same substrates. (C) 2008 Elsevier Ltd. All rights reserved.

Evaluation of culture media for enumeration of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium animalis in the presence of Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus

The study compared the growth capability of probiotic (Lactobacillus acidophilus La05, Lactobacillus casei Lc01 and Bifidobacterium animalis Bb12) and non-probiotic (Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus) cultures on twenty-one culture media grouped according to selectivity: nonselective agars, selective agars without antibiotics and MRS agars containing different combinations of lithium chloride, cystein, bile salts and antibiotics. Four of these media were selected for quantitative enumeration of L acidophilus La05, L casei Lc01, and B. animalis Bb12. The best culture media and incubation conditions for enumeration of the probiotic cultures were: B. animalis: MRS agar with dicloxacillin, 37 degrees C or 42 degrees C, anaerobiosis; L acidophilus: MRS agar with bile salts, 37 degrees C or 42 degrees C, aerobiosis; L casei: MRS agar with lithium chloride and sodium propionate, 37 degrees C or 42 degrees C, aerobiosis or anaerobiosis. Plating on MRS with glucose replaced by maltose, 37 degrees C or 42 degrees C, anaerobiosis, will distinguish probiotic from non-probiotic cultures. For enumeration of each probiotic in a mixed culture, the following media and incubation conditions were recommended: B. animalis: 4ABC-MRS, 42 degrees C, anaerobiosis, L acidophilus: LC medium, 42 degrees C, aerobiosis or anaerobiosis and L casei: LP-MRS, 42 degrees C, aerobiosis or anaerobiosis. In all experiments, differences in counts using pour plating or surface plating were not significant (P <= 0.05). (C) 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.

The tannin-degrading species Streptococcus gallolyticus and Streptococcus caprinus are subjective synonyms

The tannin-degrading species Streptococcus gallolyticus and Streptococcus caprinus have been shown to be subjective synonyms on the basis of their levels of 16S rRNA sequence similarity (98.3%) and DNA-DNA homology (>70%) and the phenotypes of their type strains. S. gallolyticus has nomenclatural priority according to Rule 24b(2) of the International Code of Nomenclature of Bacteria.

Association of Streptococcus mutans Infection and Oral Developmental Nodules in Pre-dentate Infants

Since dental caries may present soon after tooth eruption, we hypothesized that colonization of Streptococcus mutans can occur in the predentate stages. In this study, we examined S. mutans colonization and its association with oral developmental nodules (Bohn's nodules) in 60 pre-term and 128 full-term, three-month-old infants. Overall, S. mutans was cultured from 30% (56/188) of the infants, and oral developmental nodules were noted in 55% (103/188). Compared with the pre-term, full-term infants showed a higher prevalence of S. mutans (34% vs. 20%, p < 0.02) as well as developmental nodules (61% vs. 42%, p < 0.05). In both groups, S. mutans was positively associated with numbers of developmental nodules in a dose-response relationship (p < 0,001), and with maternal salivary levels of the bacteria (p = 0.03). The permanence of S. mutans infection was confirmed by repeat saliva sampling at 6 months of age. Our results thus showed that many infants have already acquired S. mutans at 3 months of age, prior to tooth eruption.

Oral Colonization of Streptococcus mutans in Six-month-old Predentate Infants

We hypothesize that S. mutans colonization occurs more frequently in pre-term children due to their relative immaturity. In this study of 172 predentate, six-month-old infants, we found that 50% of pre-term and 60% of full-term children harbored S. mutans. The colonization was confirmed by repeat sampling. Although there were minor differences, factors associated with S. mutans infection in pre-term and full-term infants were generally similar. In both groups, increased frequency of sugar was ranked the most important factor (p < 0.001), followed by breast-feeding (p < 0.001), and habits which allowed saliva transfer from mother to infant (p < 0.01). By contrast, non-colonization of S. mutans was associated with multiple courses of antibiotics (p < 0.001). Compared with pre-term children, there were higher percentages of full-term who had night feedings and consumed sugar during sleep times. Mothers with infected infants had S. mutans levels > 5 x 10(5) CFU/mL saliva (p < 0.001), poorer oral hygiene,, more periodontal disease, and lower socio-economic status (P < 0.02) and snacked frequently (p < 0.001), compared with mothers with non-infected infants.

Virulence of Streptococcus pneumoniae: PsaA mutants are hypersensitive to oxidative stress

psaA encodes a 37-kDa pneumococcal lipoprotein which is part of an ABC Mn(II) transport complex. Streptococcus pneumoniae D39 psaA mutants have previously been shown to be significantly less virulent than wild-type D39, but the mechanism underlying the attenuation has not been resolved. In this study, we have shown that psaA and psaD mutants are highly sensitive to oxidative stress, i.e., to superoxide and hydrogen peroxide, which might explain why they are less virulent than the wild-type strain. Our investigations revealed altered expression of the key oxidative-stress response enzymes superoxide dismutase and NADH oxidase in psaA and psaD mutants, suggesting that PsaA and PsaD may play important roles in the regulation of expression of oxidative-stress response enzymes and intracellular redox homeostasis.

Epidemiologia da meningite por Streptococcus pneumoniae em área metropolitana, Brasil, 1960-1977

Analisa-se o comportamento epidemiológico das meningites por S. pneumoniae no Município de São Paulo, Brasil, no período 1960-1977. Os dados foram coletados diretamente do prontuário dos pacientes e a confirmação da meningite por S. pneumoniae se fez pela bacterioscopia e/ou pela cultura do líquor. No período 1960-1977 foram confirmados 1.965 casos com um coeficiente médio de 1,9 por cem mil habitantes. As crianças menores de 5 anos contribuíram com 52% dos casos dos quais 38,5% eram menores de um ano. Os coeficientes médios por cem mil habitantes, para os menores de um ano, foram 37,1 e 30,1 para 1960-1969 e 1970-1977, respectivamente. A incidência por cem mil habitantes na zona periférica do município, na primeira década (2,3) foi o dobro daquela da zona central (1,1). Os coeficientes padronizados segundo idade foram 1,6, 1,5 e 2,0 para as zonas central, intermediária e periférica, respectiva-mente. No período seguinte estes valores foram 1,4, 1,5 e 2,0. A letalidade média no período foi de 44%, inversamente proporcional ao número de leucócitos no líquor de entrada. A letalidade entre os menores de um ano foi de 60%.

Genetic diversity and epidemiology of antimicrobial resistant Streptococcus pneumoniae isolates

Dissertation presented to obtain a Ph.D. degree in Biology, speciality in Microbiology, by Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Sorotipos de Streptococcus pneumoniae isolados de líquido cefalorraquidiano no período de 1977-1988 na cidade de São Paulo, Brasil

Desde 1977, o Instituto Adolfo Lutz (IAL) vem promovendo a sorotipagem do S. pneumoniae ou pneumococo de infecções causadas por esta bacteria. As cepas isoladas têm sido encaminhadas ao WHO Pneumococcal Reference Center, Pensilvania, E.U.A.. De 1977 a 1988, 1.000 cepas de pneumococo isoladas de LCR foram sorotipadas, de acordo com a nomenclatura dinamarquesa, e 60 sorotipos foram identificados. A maior freqüência foi do sorotipo 1, secundado por 6B, 18C, 14, 5, 3, 6A, 23F, 19F e 38. Estes sorotipos distribuídos segundo faixas etárias demonstraram incidência variável, notando-se uma certa peculiaridade, ou seja, a predominância do sorotipo 6B na faixa de zero a menos de dois anos; do sorotipo 1 na faixa de 2 até 50 anos e do sorotipo 3 no grupo acima de 50 anos. Nos 12 anos considerados, 25 sorotipos apresentaram uma certa uniformidade na freqüência e o mesmo foi observado com relação às estações climáticas, apenas com um número maior de infecções meníngeas nos meses mais frios. Considerando a gravidade das infecções pneumocócicas notadamente as meningites, e a pouca informação relativa aos sorotipos pneumocócicos que ocorrem na região, julgamos importante essa informação relativa aos sorotipos, uma vez que tem sido usadas, com sucesso, vacinas polissacarídicas na prevenção dessas infecções.

Resistance of Streptococcus pneumoniae to antimicrobials in São Paulo, Brazil: clinical features and serotypes

To study resistance to antimicrobials, serotypes and clinical features of S. pneumoniae in S. Paulo, Brazil, 50 patients with a positive culture were evaluated: 7 were considered carriers and 43 had pneumococcal infections. Pneumonia and meningitis were the most commom infections. Mortality was 34% and underlying diseases were present in 70%. Relative resistance to penicillin occurred in 24% and complete resistance was not detected. Resistance to tetracycline was 32% and to sulfamethoxazole/trimethoprim 32%; one strain had intermediate susceptibility to erythromycin; no resistance was present for chloramphenicol, rifampin or vancomycin. Resistance to at least one of the drugs tested occurred in 62%. Results by the E-test for penicillin were similar to those by the agar dilution method. There were 24 different serotypes and 74% of the strains belonged to the 23-valent vaccine including all the penicillin-resistant strains. In this study S. pneumoniae caused severe infections and presented a high resistance rate to commonly used antimicrobials. Routine surveillance of resistance and the use of vaccination, as well as the restriction of inappropriate use of antimicrobials, are recommended in São Paulo, Brazil.