Microbiological and fermentative properties of baker's yeast starter used in breadmaking.

This study assessed the levels of microbial contaminants in liquid, compressed and dry commercial baker's yeasts used as starters in breadmaking. Eumycetes, Enterobacteriaceae, total and fecal coliforms, Bacillus spp., and lactic acid bacteria (LAB), in particular enterococci, were quantified. Results obtained in this study highlighted that baker's yeast could represent a potential vehicle of spoilage and undesirable microorganisms into the baking environment, even if these do not influence the leavening activity in the dough, as ascertained by rheofermentometer analysis. Different microbial groups, such as spore-forming bacteria and moulds, were found in baker's yeast starters. Moreover, different species of LAB, which are considered the main contaminants in large-scale yeast fermentations, were isolated and identified by Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rDNA sequencing. The most recurrent species were Lactobacillus plantarum, Enterococcus faecalis, and Enterococcus durans, isolated from both compressed and dry starters, whereas strains belonging to Leuconostoc and Pediococcus genera were found only in dry ones. Nested-Polymerase Chain Reaction (Nested-PCR) and Randomly Amplified Polymorphic DNA-PCR (RAPD-PCR) were also used to highlight the biodiversity of the different commercial yeast strains, and to ascertain the culture purity.

Karyotype and spermatogenesis in Triatoma lenti (Hemiptera: Triatominae), a potential Chagas vector.

All species of Triatominae are susceptible to infection by Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) and consequently, potential insect vectors of Chagas disease. Currently, there are 140 known species of triatomine bugs, which can be grouped into specific species complexes. The species Triatoma lenti (Hemiptera: Triatominae) is found only in Brazil and is considered a potential vector of Chagas disease. We karyotyped male T. lenti and examined its spermatogenesis in detail. The karyotype was found to be 2n = 20A + XY, demonstrating that this organism has the modal chromosome set found in triatomines. This new information concerning males of this species contributed to biological data that will be useful for understanding this potentially important Chagas disease vector.

Interactions between Lactobacillus sakei and CNC (Staphylococcus xylosus and Kocuria varians) and their influence on proteolytic activity.

AIMS: To evaluate interactions between Lactobacillus sakei and coagulase negative cocci (CNC) (Staphylococcus xylosus and Kocuria varians) and to investigate the influence of these interactions on their own proteolytic activity. METHODS AND RESULTS: Interactions occurring between strains of Lact. sakei and CNC were assessed by spectrophotometric analysis. The growth of 35 strains of Lact. sakei, used as indicators, was compared to that obtained combining the same strains with growing cells or cell-free supernatants of 20 CNC (18 Staph. xylosus and 2 K. varians). The proteolytic activity expressed by single strains or by their combinations was assessed on sarcoplasmic protein extracts by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results evidenced that interactions are able to affect not only the growth but also the in vitro proteolytic activity of Lact. sakei and CNC used in combination. CONCLUSIONS: A relationship between the presence of interactions among useful strains and the strength of technological characteristics, such as proteolysis, was defined. SIGNIFICANCE AND IMPACT OF THE STUDY: The study highlighted that CNC are able to stimulate the growth of some Lact. sakei strains. At the same time, this interaction positively influences the proteolytic activity of strains used in combination. Given the importance of proteolysis during the ripening of fermented meats, this phenomenon should be taken into account to select meat starter cultures.

Interactions between strains of Staphylococcus xylosus and Kocuria varians isolated from fermented meats.

AIMS: To evaluate the interactions of Staphylococcus xylosus on Kocuria varians strains isolated from fermented meat products. METHODS AND RESULTS: Interactions were assessed in vitro by agar spot test, agar well diffusion assay and spectrophotometric assay. The growth of K. varians (five strains) alone was compared with that in the presence of growing cells of S. xylosus (50 strains) or in the presence of heat-treated or untreated supernatants of S. xylosus. Sixteen strains stimulated the growth of K. varians K4, while four strains inhibited the K4 strain. Heated cell-free supernatants of S. xylosus did not have any effect on K. varians. The proteolytic activity of single strains or their combinations was assessed in vitro and in vivo by sodiumdodecylsulfate-polyacrylamide gel electrophoresis of sarcoplasmic protein extracts. Combinations of stimulatory strains of S. xylosus and K. varians showed a higher proteolytic activity compared with that of S. xylosus or K. varians alone. CONCLUSIONS: The interactions between strains may influence both the growth of the co-cultured strains and proteolysis, technologically relevant characteristics. SIGNIFICANCE AND IMPACT OF THE STUDY: The study of interactions between coagulase-negative cocci may guide the formulation of mixed strain starters for the production of fermented sausages.

Shelf life of fresh sausages stored under modified atmospheres.

The aim of this study was to investigate differences in modified atmosphere packaging (MAP) for the improvement of the shelf life of fresh meat products. Three different conditions for preserving fresh sausages were tested: MAP1 (20% CO2, 70% O2, and 10% N2), MAP2 (40% CO2 and 60% O2), and MAP3 (40% CO2, 30% O2, and 30% N2). Samples from the MAP2 group had fewer spoilage bacteria, stable red color (no change of a* value), and good physical attributes (high water-holding capacity, little loss from cooking, and low shear force needed for cutting) compared with samples from other treatment groups. Thus, high concentrations of CO2 (40%) and O2 (60%) resulted in a longer shelf life for fresh sausages.

Bile salt and acid tolerance of Lactobacillus rhamnosus strains isolated from Parmigiano Reggiano cheese.

This study aimed to compare phenotypic and genetic characteristics of Lactobacillus rhamnosus strains isolated at the end of the ripening of Parmigiano Reggiano cheese and to investigate an important prerequisite of probiotic interest, such as the capability to survive at low pH and in presence of bile salts. The use of API 50 CH, RAPD-PCR analysis and species-specific PCR allowed to ascertain the identity of 63 L. rhamnosus strains. Three L. rhamnosus strains isolated from Parmigiano Reggiano cheese, L. rhamnosus ATCC 7469T and the commercial strain L. GG were assayed to estimate the resistance to various stress factors reproducing in vitro some conditions of the gastro-intestinal environment such as low pH and different amounts of bile salts and acids. The behaviour of almost all the tested strains isolated from Parmigiano Reggiano cheese resulted analogous to that showed by L. GG.

Presence of yeasts in southern Italian sourdoughs from Triticum aestivum flour.

Samples of sourdoughs obtained from 13 artisanal bakeries located in the Molise and Campania regions were analysed. The sourdoughs were produced with the exclusive use of Triticum aestivum wheat flour. pH values of sourdoughs from Molise were generally lower than those from Campania. The number of yeasts in the samples of sourdoughs from Molise was generally higher than in those from Campania, which in two cases evidenced counts about 2 log cfu x g(-1). By utilising and comparing traditional and biomolecular techniques of identification a complete picture of the isolates was obtained: 58 strains were identified as Saccharomyces cerevisiae, five as Candida colliculosa, four as C. lambica, three as C. krusei, three as C. valida and two as C. glabrata.

Change in the population of health systems: from 1985 to 1998.

This article compares the predictions in Stephen Shortell's 1988 seminal article, The Evolution of Hospital Systems: Unfulfilled Promises and Self-Fulfilling Prophesies, with current data on health systems over a 14-year period from 1985 to 1998. Specifically, we review five of Shortell's predictions related to the horizontal growth of health systems and compare these predictions with empirical data on structural changes in the population of health systems. Our analyses suggest that Shortell's predictions corresponded to much of the actual behavior demonstrated in the population over the past one-and-a-half decades. Support was found for the following: (1) health systems form in two recurring stages; (2) previously unaffiliated hospitals are affiliating with existing systems rather than participating in the creation of new systems; and (3) health systems have evolved into five different strata, each of which represents different shares of the population; such population patterns have important implications for individual hospitals and health systems. By attending to patterns of change in the industry's social structure, hospitals and health systems can determine whether it is likely to continue along past trajectories or whether it shows signs of change that may pave way for the breakdown of existing organizational forms, entry of new organizational players, and the emergence of new governance structures.

Community accountability among hospitals affiliated with health care systems.

The shift from local, community-based hospitals to more complex, multilevel delivery systems raises questions about the community accountability exercised by hospitals. A national sample of community hospitals is the basis of this study, which examines the ways that community accountability is exercised by the governing boards of hospitals affiliated with health care systems and how such institutions compare with hospitals not affiliated with a health care system. Results indicate that hospitals display community accountability in a variety of ways. Boards of system-affiliated hospitals exercise community accountability most strongly in their information monitoring and reporting activities, whereas free-standing hospitals exercise community accountability through the structural and compositional attributes of their boards. Further, hospitals affiliated with different types of systems vary in the style and degree of accountability they demonstrate.

Physician involvement in management and governance: the moderating effects of staff structure and composition.

Many hospitals are actively pursuing strategies that integrate physicians into their management and governance structures. Despite expectations that these strategies improve hospital efficiency, empirical studies have failed to provide consistent evidence that physician involvement in hospital management and governance improves hospital efficiency. This article examines factors that may moderate the relationship between physician participation in hospital management and governance and hospital efficiency.

Trust between managers and physicians in community hospitals: the effects of power over hospital decisions.

Trust is a key element of effective work relationships between managers and physicians. Despite its importance, little is known about the factors that promote trust between these two professional groups. We examine whether manager and physician power over hospital decisions fosters manager-physician trust. We expect that with more power, managers and physicians will have greater control to enforce decisions that benefit the interests of both groups. Subsequently, they may gain confidence that their interests are supported and have more trust for each other. We test proposed hypotheses with data collected in a national study of chief executive officers and physician leaders in community hospitals in 1993. Findings indicate that power of managers and physicians over hospital decisions is related to manager-physician trust. Consistent with our expectations, physicians perceive greater trust between the two groups when they hold more power in four separate decision-making areas. Our hypotheses, however, are only partially supported in the manager sample. The relationship between power and trust holds in only one decision area: cost/quality management. Our findings have important implications for physician integration in hospitals. A direct implication is that physicians should be given the opportunity to influence hospital decisions. New initiatives, such as task force committees with open membership or open forums on hospital management, allow physicians a more substantial involvement in decisions. Such initiatives will give physicians more "voice" in hospital decision making, thus creating opportunities for physicians to express their interests and play a more active role in the pursuit of the hospital's mission and objectives.

Effects of market position and competition on rural hospital closures.

OBJECTIVE: To examine the dynamic effects of competition and hospital market position on rural hospital closures. DATA SOURCE/STUDY SETTING: Analysis of all rural community hospitals operating between 1984 and 1991, with the exception of sole-provider hospitals. Data for the study are obtained from four sources: the AHA Annual Surveys of Hospitals, the HCFA Cost Reports, the Area Resource File, and a hospital address file constructed by Geographic Inc. DATA COLLECTION AND ANALYSIS: Variables are merged to construct pooled, time-series observations for study hospitals. Hospital closure is specified as a function of hospital market position, market level competition, and control variables. Discrete-time logistic regressions are used to test hypotheses. PRINCIPAL FINDINGS: Rural hospitals operating in markets with higher density had higher risk of closure. Rural hospitals that differentiated from others in the market on the basis of geographic distance, basic services, and high-tech services had lower risks of closure. Effects of market density on closure disappeared when market position was included in the model, indicating that differentiation in markets should be taken into account when evaluating the effects of competition on rural hospital closure. CONCLUSIONS: Our findings suggest that rural hospitals can reduce competitive pressures through differentiation and that accurate measures of competition in geographically defined market areas are critical for understanding competitive dynamics among rural hospitals.

State legislation and policy affecting rural hospital conversion and closure.

Many rural hospitals have closed or converted to organizations that provide health services other than general, acute inpatient care. However, little is known about why rural hospitals convert rather than close. This study evaluates the relationship between state policy and rates of rural hospital conversion relative to rates of rural hospital closure. The expectation was that the relationship among state policies and rates of conversion and rates of closure differs as a function of whether a state policy facilitates rural hospital transition to alternative models of care or supports them in their existing form. National data were analyzed for all rural hospitals from 1984 to 1991. Results indicate that state policies have done little to facilitate widespread adoption of conversion among rural hospitals. Despite these findings, results also indicate that some state policies have resulted in an increase in the rate of rural hospitals conversions as an alternative to closure.

Determinants of profound organizational change: choice of conversion or closure among rural hospitals.

Because of severe operating and resource constraints, many rural community hospitals are confronted with pressures to abandon core strategies related to acute inpatient care. Little is known, however, about why hospitals would choose to convert to organizations that provide non-acute care health services as an alternative to closure. We argue that rural hospitals are more likely to convert when conditions are in place that enable them to make major shifts from their current domains to ones that are more hospitable. To the extent that resources are available in alternative domains and rural hospitals possess the strategies necessary to exploit these resources, rural hospitals are more likely to convert rather than close. To examine our proposed hypotheses, we analyze national data from all rural hospitals from 1984 through 1991. Results indicate that conversion is more likely to occur than closure when resources in the market are abundant, competition for hospital resources is high, and hospitals have established strategies to provide alternative forms of health care. Findings from this study indicate that environmental and organizational factors can increase a rural hospital's risk of conversion as an alternative to closure.

Determinants of rural hospital conversion. A model of profound organizational change.

One widely discussed response to the severe problems faced by many rural hospitals is to convert them into organizations that provide health services other than general, acute inpatient care. This study identifies conversions that occurred nationally from 1984 to 1991. The study also empirically examines the determinants of conversion, using rural hospitals that did not convert (between 1984 and 1991) as a comparison group. The authors examine a set of factors that makes radical organizational change necessary (eg, poor performance) and reduces resistance to such change (eg, proximity to other hospitals). Results from discrete-time logistic regression show that converters are more likely than nonconverters to: have poor performance and fewer beds; be located very near to or very distant from similar hospitals; operate in larger communities; devote more of their care to areas other than acute inpatient care; and be members of multihospital systems. Converters also are less likely to be government owned. The need for future research on the effects of conversion is discussed.