Concomitant Bacteria Research Articles

Prevalence of Concomitant Bacteria among malaria Patients attending Government Hospitals in Ondo State, South-West Nigeria

Background:Patients suffering from severe malaria have an increased risk of co-occurring bacterial sepsis, which results in higher mortality rates than malaria alone. Concomitant bacterial infections can worsen malaria symptoms, leading to increased illness and death rates. This study aimed to investigate the relationship between malaria and concomitant bacteremia among patients in Ondo State, Nigeria.Aim: The study's objective was to determine the prevalence of bacterial concomitant among malaria patients and assess the relationship between malaria and bacteremia in the study population.Material and Methods: A cross-sectional study was conducted among feverish individuals in certain Ondo State government hospitals. One milliliter of blood was collected from malaria-positive patients, confirmed using microscopic examination of Giemsa-stained thick and thin blood films, and an Malaria rapid diagnostic tests (RDT) kit was cultured for bacterial enumeration. The collected data were statistically analyzed using Chi-square and correlation tests, with a 𝑃value <0.05 considered significant.Result: The study found a concomitant bacteria prevalence of 19.95% (85/426), with a significant (P= <0.001, r = 0.00334) positive correlation between malaria and bacterial concomitant.Age was significantly (p = 0.072, df= 18, χ2 = 27.389) associated with bacterial concomitant, and the mean bacterial count was 9.71±1.481 cfu/ml x 107. Furthermore, level of education, marital status and tribe also significantly (p<0.05) contributed to the prevalence of concomitant bacteria.Conclusion: Our research concludes that malaria may increase the risk of bacteremia, and a significant association between malaria and concomitant bacterial infection exists. However, the reasons for bacteria's abilityto invade and thrive in the bloodstream vary. The study's findings suggest that interventions are needed to address the high prevalence of concomitant bacterial infections among malaria patients in the study area.

Incidence, clinical characteristics, risk factors and outcomes of patients with mixed Candida/bacterial bloodstream infections: a retrospective study

PurposeThe mixed Candida/bacterial bloodstream infections (mixed C/B-BSIs) is worthy of particular attention recently, and we analyzed the incidence, co-pathogens, clinical characteristics, risk factors, and outcomes of mixed C/B-BSIs compared with monomicrobial candidemia (mono-candidemia) in adult patients in China.MethodsAll hospitalized adults with candidemia were recruited for this retrospective observational study from January 1, 2013, to December 31, 2019.ResultsOf the 296 patients with candidemia, 78 cases (26.3%) were mixed C/B-BSIs. Candida albicans (C. albicans) was the most common Candida species among all candidemia, and Klebsiella pneumoniae (K. pneumoniae) was the most concomitant bacteria (30.6%), followed by Acinetobacter baumannii (A. baumannii) (12.9%) and Enterococcus faecium (E. faecium) (11.8%) in mixed C/B-BSIs. In the multivariable analysis, prior β-lactams exposure [adjusted odds ratio (aOR), 1.97; 95% confidence interval (CI), 1.01–3.87], burn injury (aOR, 6.35; 95% CI 1.82–22.21) and continuous renal replacement therapy (CRRT) (aOR, 3.00; 95% CI 1.46–6.17) were independent risk factors for mixed C/B-BSIs. Compared with mono-candidemia, patients with mixed C/B-BSIs developed with more proportion of septic shock (55.1% vs. 39.9%, P < 0.05), prolonged stay in ICU [22.0(12.0–57.0) vs. 9.5(0.0–37.0) days, P < 0.001] and longer mechanical ventilation time [19.0(4.5–40.8) vs. 6.0(0.0–24.8) days, P < 0.001]. The in-hospital mortality in patients with mixed C/B-BSIs was higher than those with mono-candidemia (59.0% vs. 34.9%, P < 0.001). Survival analysis revealed that 28-day and 60-day mortality were significantly higher in patients with mixed C/B-BSI than in those with mono-candidemia (57.7% vs. 31.7%, P < 0.001; 59.0% vs. 34.9%, P < 0.001; respectively).ConclusionsThere is a high rate of mixed C/B-BSIs cases among candidemia, and K. pneumoniae is the predominant coexisting species. Prior β-lactams exposure, burn injury, and CRRT are independent risk factors for mixed C/B-BSIs. The mortality of patients with mixed C/B-BSIs is significantly higher than those with mono-candidemia, this deserves further attention for clinicians.

Impact of Modified Atmospheres on Growth and Metabolism of Meat-Spoilage Relevant Photobacterium spp. as Predicted by Comparative Proteomics.

Modified atmosphere packaging (MAP) is a common strategy to selectively prevent the growth of certain species of meat spoiling bacteria. This study aimed to determine the impact of high oxygen MAP (70% O2, 30% CO2, red and white meats) and oxygen-free MAP (70% N2, 30% CO2, also white meat and seafood) on preventing the growth of spoiling photobacteria on meat. Growth of Photobacterium carnosum and P. phosphoreum was monitored in a meat simulation media under different gas mixtures of nitrogen, oxygen, and carbon dioxide, and samples were taken during exponential growth for a comparative proteomic analysis. Growth under air atmosphere appears optimal, particularly for P. carnosum. Enhanced protein accumulation affected energy metabolism, respiration, oxygen consuming reactions, and lipid usage. However, all the other atmospheres show some degree of growth reduction. An increase in oxygen concentration leads to an increase in enzymes counteracting oxidative stress for both species and enhancement of heme utilization and iron-sulfur cluster assembly proteins for P. phosphoreum. Absence of oxygen appears to switch the metabolism toward fermentative pathways where either ribose (P. phosphoreum) or glycogen (P. carnosum) appear to be the preferred substrates. Additionally, it promotes the use of alternative electron donors/acceptors, mainly formate and nitrate/nitrite. Stress response is manifested as an enhanced accumulation of enzymes that is able to produce ammonia (e.g., carbonic anhydrase, hydroxylamine reductase) and regulate osmotic stress. Our results suggest that photobacteria do not sense the environmental levels of carbon dioxide, but rather adapt to their own anaerobic metabolism. The regulation in presence of carbon dioxide is limited and strain-specific under anaerobic conditions. However, when oxygen at air-like concentration (21%) is present together with carbon dioxide (30%), the oxidative stress appears enhanced compared to air conditions (very low carbon dioxide), as explained if both gases have a synergistic effect. This is further supported by the increase in oxygen concentration in the presence of carbon dioxide. The atmosphere is able to fully inhibit P. carnosum, heavily reduce P. phosphoreum growth in vitro, and trigger diversification of energy production with higher energetic cost, highlighting the importance of concomitant bacteria for their growth on raw meat under said atmosphere.

Black Mn-containing layered double hydroxide coated magnesium alloy for osteosarcoma therapy, bacteria killing, and bone regeneration.

Osteosarcoma (OS) tissue resection with distinctive bactericidal activity, followed by regeneration of bone defects, is a highly demanded clinical treatment. Biodegradable Mg-based implants with desirable osteopromotive and superior mechanical properties to polymers and ceramics are promising new platforms for treating bone-related diseases. Integration of biodegradation control, osteosarcoma destruction, anti-bacteria, and bone defect regeneration abilities on Mg-based implants by applying biosafe and facile strategy is a promising and challenging topic. Here, a black Mn-containing layered double hydroxide (LDH) nanosheet-modified Mg-based implants was developed. Benefiting from the distinctive capabilities of the constructed black LDH film, including near-infrared optical absorption and reactive oxygen species (ROS) generation in a tumor-specific microenvironment, the tumor cells and tissue could be effectively eliminated. Concomitant bacteria could be killed by localized hyperthermia. Furthermore, the enhanced corrosion resistance and synergistic biofunctions of Mn and Mg ions of the constructed black LDH-modified Mg implants significantly facilitated cell adhesion, spreading and proliferation and osteogenic differentiation in vitro, and accelerated bone regeneration in vivo. This work offers a new platform and feasible strategy for OS therapeutics and bone defect regeneration, which broadens the biomedical application of Mg-based alloys.

Identification of genes encoding a novel ABC transporter in Lactobacillus delbrueckii for inulin polymers uptake

Lactobacillus delbrueckii JCM 1002T grows on highly polymerized inulin-type fructans as its sole carbon source. When it was grown on inulin, a > 10 kb long gene cluster inuABCDEF (Ldb1381-1386) encoding a plausible ABC transporter was suggested to be induced, since a transcriptome analysis revealed that the fourth gene inuD (Ldb1384) was up-regulated most prominently. Although Bacillus subtilis 168 is originally unable to utilize inulin, it became to grow on inulin upon heterologous expression of inuABCDEF. When freshly cultured cells of the recombinant B. subtilis were then densely suspended in buffer containing inulin polymers and incubated, inulin gradually disappeared from the buffer and accumulated in the cells without being degraded, whereas levan-type fructans did not disappear. The results imply that inuABCDEF might encode a novel ABC transporter in L. delbrueckii to “monopolize” inulin polymers selectively, thereby, providing a possible advantage in competition with other concomitant inulin-utilizing bacteria.

Isolation and identification of milk oligosaccharide-degrading bacteria from the intestinal contents of suckling rats.

We report the isolation of bacteria capable of degrading milk oligosaccharides from suckling infant rats. The bacteria were successfully isolated via a selective enrichment method, in which the serially diluted intestinal contents of infant rats were individually incubated in an enrichment medium containing 3′-sialyllactose (3′-SL), followed by the isolation of candidate strains from streaked agar plates and selection of 3′-SL-degrading strains using thin-layer chromatography. Subsequent genomic and phenotypic analyses identified all strains as Enterococcus gallinarum. The strains were capable of degrading both 3′-SL and 6′-SL, which was not observed with the type strain of E. gallinarum used as a reference. Furthermore, a time-course study combining high-performance anion-exchange chromatography with pulsed amperometric detection revealed that the representative strain AH4 degraded 3′-SL completely to yield an equimolar amount of lactose and an approximately one-fourth equimolar amount of sialic acid after 24 hr of anaerobic incubation. These findings point to a possibility that the enterococci degrade rat milk oligosaccharides to “cross-feed” their degradants to other members of concomitant bacteria in the gut of the infant rat.

Liver-derived mitochondria drive CD8 T-cell dysfunction, alter purinergic signaling and impair bacterial clearance in the lung in vivo

Abstract Trauma is the leading cause of death in young adults. The pathogenetic mechanisms resulting in posttraumatic immunosuppression with increased susceptibility to infection remain unclear. Mitochondria (MT) are released by cells after trauma and can generate danger molecules, such as extracellular ATP (eATP). The vascular and immune cell ectonucleotidase CD39 scavenges eATP to generate immunosuppressive derivatives such as adenosine. Here, we examined the role of eATP generated by exogenous mitochondria in modulating the immune response and provoking immunosuppression in the context of experimental pneumonia models. ATP probes and MitoSOX revealed that liver-derived MT generate ATP and ROS ex vivo. When injected into recipient mice, MT isolated from mouse liver induced upregulation of CD39 and CD73 expression on circulating CD8 T cells and promoted immune cell exhaustion. Next, wild-type mice were injected intraperitoneally with liver MT, followed by intratracheal instillation of pathogenic S. aureus. Mice receiving MT were unable to clear bacteria, as demonstrated by elevated CFU counts in the bronchoalveolar lavage, when compared to mice with bacterial instillation alone. Histological analysis confirmed more pronounced lung injury with infiltration of inflammatory neutrophils in mice administered both MT and bacteria, when compared to mice instilled only with bacteria. Lastly, the MT injection with concomitant bacteria administration resulted in loss of lung-derived CD8 T-cells. Our data indicate that ATP generation by exogenous mitochondria boost CD39 expression in circulating CD8 T-cells and drive dysfunctional immune responses in mice that result in increased susceptibility to bacterial infection of the lungs.

Пути решения проблем выделения протеев в ветеринарии

When studying isolates from waste of processing animal meat products and mechanically deboned meat the comparative analysis of nutrient media was done. The assessment of the growth of bacteria of the genus Proteus on the media based on such parameters as productivity, differentiating and inhibiting properties. Of special interest is a new highly selective nutrient media tested in the veterinary laboratory. It has been shown that the domestic differential diagnostic medium to isolate bacteria of the genera Proteus, Morganella, and Providencia is characterized by high productivity and significant inhibitory properties to be used in veterinary medicine to analyze any material contaminated with proteins along with concomitant bacteria. Key words: veterinary medicine, nutrient media, Proteus, differentiating properties, selectivity

Effect of Sex and Age of Human on Infection With Types of Stones and Its Concomitant Bacteria

Effect of Sex and Age of Human on Infection With Types of Stones and Its Concomitant Bacteria

Evaluation of zinc oxide nanoparticles on lettuce (Lactuca sativa L.) growth and soil bacterial community.

The wide spread of nanoparticles (NPs) has caused tremendous concerns on agricultural ecosystem. Some metallic NPs, such as zinc oxide (ZnO), can be utilized as a nano-fertilizer when used at optimal doses. However, little is known about the responses of plant development and concomitant soil bacteria community to ZnO NPs. The present pot experiment studied the impacts of different doses of ZnO NPs and bulk ZnO (0, 1, 10, 100mg ZnO/kg), on the growth of lettuce (Lactuca sativa L.) and the associated rhizospheric soil bacterial community. Results showed that at a dose of 10mg/kg, ZnO NPs and bulk ZnO, enhanced the lettuce biomass and the net photosynthetic rate; whereas, the Zn content in plant tissue was higher in NPs treatment than in their bulk counterpart at 10mg/kg dose or higher. For the underground observations, 10mg/kg treatment doses (NPs or bulk) significantly changed the soil bacterial community structure, despite the non-significant variations in alpha diversity. Taxonomic distribution revealed that some lineages within Cyanobacteria and other phyla individually demonstrated similar or different responses to ZnO NPs and bulk ZnO. Moreover, some lineages associated with plant growth promotion were also influenced to different extents by ZnO NPs and bulk ZnO, suggesting the distinct microbial processes occurring in soil. Collectively, this study expanded our understanding of the influence of ZnO NPs on plant performance and the associated soil microorganisms.

Vitamin B12 sources and microbial interaction.

Vitamin B12 is synthesized only by certain bacteria and archaeon, but not by plants. The synthesized vitamin B12 is transferred and accumulates in animal tissues, which can occur in certain plant and mushroom species through microbial interaction. In particular, the meat and milk of herbivorous ruminant animals (e.g. cattle and sheep) are good sources of vitamin B12 for humans. Ruminants acquire vitamin B12, which is considered an essential nutrient, through a symbiotic relationship with the bacteria present in their stomachs. In aquatic environments, most phytoplankton acquire vitamin B12 through a symbiotic relationship with bacteria, and they become food for larval fish and bivalves. Edible plants and mushrooms rarely contain a considerable amount of vitamin B12, mainly due to concomitant bacteria in soil and/or their aerial surfaces. Thus, humans acquire vitamin B12 formed by microbial interaction via mainly ruminants and fish (or shellfish) as food sources. In this review, up-to-date information on vitamin B12 sources and bioavailability are also discussed. Impact statement To prevent vitamin B12 (B12) deficiency in high-risk populations such as vegetarians and elderly subjects, it is necessary to identify foods that contain high levels of B12. B12 is synthesized by only certain bacteria and archaeon, but not by plants or animals. The synthesized B12 is transferred and accumulated in animal tissues, even in certain plant tissues via microbial interaction. Meats and milks of herbivorous ruminant animals are good sources of B12 for humans. Ruminants acquire the essential B12 through a symbiotic relationship with bacteria inside the body. Thus, we also depend on B12-producing bacteria located in ruminant stomachs. While edible plants and mushrooms rarely contain a considerable amount of B12, mainly due to concomitant bacteria in soil and/or their aerial surfaces. In this mini-review, we described up-to-date information on B12 sources and bioavailability with reference to the interaction of microbes as B12-producers.

Activity of antioxidant enzymes in response to atmospheric pressure induced physiological stress in deep-sea hydrothermal vent mussel Bathymodiolus azoricus

Deep sea hydrothermal Bathymodiolus azoricus mussels from Portuguese EEZ Menez Gwen hydrothermal field possess the remarkable ability to overcome decompression and survive successfully at atmospheric pressure conditions. We investigated the potential use of antioxidant defense enzymes in mussel B. azoricus as biomarkers of oxidative stress induced by long term acclimatization to atmospheric pressure conditions. Mussels collected at Menez Gwen hydrothermal field were acclimatized for two weeks in three distinct conditions suitable of promoting physiological stress, (i) in plain seawater for concomitant endosymbiont bacteria loss, (ii) in plain seawater under metal iron exposure, (iii) constant bubbling methane and pumped sulfide for endosymbiont bacteria survival. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and iron storage proteins in addition to electrophoretic profiles were examined in vent mussel gills and digestive gland. Gills showed approximately 3 times more SOD specific activity than digestive glands. On the other hand, digestive glands showed approximately 6 times more CAT specific activity than gills. Iron storage proteins were identified in gill extracts from all experimental conditions mussels. However, in digestive gland extracts only fresh collected mussels and after 2 weeks in FeSO4 showed the presence of iron storage proteins. The differences between SOD, CAT specific activities and the presence of iron storage proteins in the examined tissues reflect dissimilar metabolic and antioxidant activities, as a result of tissue specificities and acclimatization conditions influences on the organism.

Concomitant bacteria in the blood of malaria patients in Owerri, southeastern Nigeria

The presence of concomitant bacteria was assessed in the blood of 125 malaria positive patients and 60 malaria negative controls, resident in Owerri, southeastern Nigeria. Blood samples were cultured in MacConkey, Chocolate and Blood agar, respectively using oxoid signal system after the manufacturer's instructions. Blood cultures of 44 (35.2%) of the 125 malaria positive patients had bacterial growth while none was observed in the blood cultures of malaria negative patients. The bacteria species identified included: Staphylococcus aureus 4 (3.2%), Escherichia coli 3 (2.4%) Salmonella typhi 25 (20%), Klebsiella pneumoniae 10 (2.4%) and Pseudomonas aeruginosa 2 (1.6%). The presence of concomitant bacteria in malaria-positive cases usually results in persistence of malaria-like symptoms after treatment with antimalarials and subsequently taken as resistance of the parasites to the particular drugs in question. The significance of concomitant bacteria in the management of malaria should be given priority.

Zur Antibiotikabehandlung der menschlichen Aktinomykosen

In the complex aetiology of human actinomykoses, various Actinomyces species, especially A. israelii, play the pathogenetically leading role in the mixed flora so typical for these diseases. A number of other microaerophilic and anaerobic bacteria are also part of such mixed flora. Since these "concomitant" bacteria are themselves potentially pathogenic, it is important to have data on antibiotic sensitivity for the entire spectrum of microorganisms, to achieve effective and economic chemotherapy of human actinomykoses. Minimal inhibitory concentrations of antibiotics were determined for Actinomyces and the most important concomitant bacteria from actinomykotic processes: Actinobacillus actinomycetem-commitants, Bacteroides of the Melaninogenicus group, B. fragilis, B. theta-iotaomicron, Fusobacterium nucleatum, Fusobacterium spp. and Propionibacteria. The results indicate that aminopenicillines are the drug of first choice, if in the actinomykoses there are no Bacteroides strains resistant to beta-lactam antibiotics. These tests further indicate that clinically the combination of aminopenicillin and clindamycin, as well as aminopenicillin and metronidazol, are indicated. Minocycline and especially cefoxitin, a beta-lactamase resistant cephalosporin, inhibit with few exceptions all bacteria which are potentially involved in actinomykotic processes.

Prognostic factors and impact of antibiotherapy in 117 cases of anaerobic bacteraemia

Bacteraemia due to anaerobic bacteria occurs infrequently, making the systematic use of an anaerobic blood sample bottle in patients with sepsis controversial. We retrospectively reviewed the clinical and microbiological data from all cases of anaerobic bacteraemia in a teaching hospital over 2 years and determined the prognostic factors and antibiotic management. With the goal of evaluating the morbidity and mortality of bacteraemia due to anaerobic bacteria, a case-control study was also performed. One hundred eighty-four blood cultures from 125 patients grew at least one anaerobic bacterium, representing 0.5% of all and 7.0% of the positive blood cultures. One hundred seventeen patients were studied. In 24 cases, anaerobic blood cultures were associated with concomitant aerobic bacteria isolation. The most frequently isolated anaerobic species were Bacteroides sp. (n = 62), Clostridium sp. (n = 25), and Fusobacterium sp. (n = 12). The most frequent site of origin was the digestive tract (n = 61). In 51 cases, patients did not receive adequate empirical antianaerobic therapy. The mortality rate was 27%. Age [odds ratio (OR) 1.059; 95% confidence interval (CI) 1.021-1.100], cancer history (OR 3.21, 95% CI 1.126-9.156), and ineffective definitive antibiotherapy (OR 19.292, 95% CI 5.330-69.832) were independently associated with increased hospital mortality. The 72 patients that could be matched with patients without anaerobic bacteria according to their primary diagnosis had a longer hospitalisation and a trend toward increased mortality (P = 0.08). Anaerobic bacteraemia contributed significantly to the morbidity of the patients, and adequate empirical antibiotherapy may play an important role in the clinical outcomes.

Pulmonary bacterial co-infection in children ventilated for severe respiratory syncytial virus bronchiolitis is common

Sir, In a retrospective study on concurrent bacterial infection in infants ventilated for respiratory syncytial virus (RSV), bronchiolitis Kneyber et al. concluded that the “improvement in the diagnosis of a pulmonary concurrent bacterial infection is warranted to reduce the overuse of antimicrobial drugs” in this patient group [1]. This issue was highlighted by Andrews et al. in “Intensive Care Medicine’s Year in Review” 2005 article [2] as “Only a minority had evidence of bacterial infection”. Our view differs and we question this opinion/interpretation. A prospective study of 165 consecutive children in whom an admission broncho-alveolar lavage (BAL) sample was obtained found that up to 40% of patients admitted with severe RSV bronchiolitis were infected with bacteria in their lower airways [3]. This is in keeping with Kneyber et al. who found that 33% of children (9 of 24) in whom admission endotracheal aspirates were performed had a positive bacterial culture [1]. Duttweiler et al. retrospectively studied 127 infants admitted to intensive care for RSV bronchiolitis and found that 44% of those ventilated and endotracheally sampled had “concomitant bacteria pneumonia” [4]. Likewise, Randolph et al. retrospectively examined 165 previously healthy infants admitted to the intensive care unit with laboratoryconfirmed RSV infection and found that up to 38% of the intubated infants had “probable” or “possible” bacterial pneumonia [5]. Pulmonary bacterial co-infection is common in children ventilated for severe RSV bronchiolitis. The statement, “Only a minority had evidence of bacterial infection” [2] underscores the incidence in this patient group. Kneyber et al. [1] and Thorburn et al. [3] acknowledged that their studies may even have underestimated the actual number of concurrent bacterial infections. All the patients in both these studies [1, 3] received concomitant antibiotics, which limits any interpretation on the influence of antibiotics on outcome. This also limits comment on the “overuse of antimicrobials” [1, 2]. The only way to prove a definite impact of antimicrobials in this study population would be to carry out a randomized control trial. In the interim, one could argue that a bacterial co-infection rate of up to 40% in ventilated RSV patients is sufficient to warrant prophylactic/empirical antibiotics on admission to the paediatric intensive care unit (PICU). These critically ill children run a serious risk of developing bacterial pneumonia [6]. While awaiting further studies, we think that empirical antibiotic therapy appears to be justified in children with severe RSV bronchiolitis, pending the results of definitive cultures. “Improvement in the diagnosis of a pulmonary concurrent bacterial infection” can be achieved by obtaining lower airways secretions on admission to PICU in all patients. In the absence of finding bacteria in the lower airways, antibiotics can subsequently be stopped. References

Population dynamics of an algal–bacterial cenosis in closed ecological system

The paper deals with microalgae–bacteria interrelationships in the “autotroph–heterotroph” aquatic biotic cycle. Explanations of why and how algal–bacterial ecosystems are formed still remain controversial. The paper presents results of experimental and theoretical investigations of the functioning of the algal–bacterial cenosis (the microalga Chlorella vulgaris and concomitant microflora). The Chlorella microbial community is dominated by representatives of the genus Pseudomonas. Experiments with non-sterile batch cultures of Chlorella on Tamiya medium showed that the biomass of microorganisms increases simultaneously with the increase in microalgal biomass. The microflora of Chlorella can grow on organic substances released by photosynthesizing Chlorella. Microorganisms can also use dying Chlorella cells, i.e. form a “producer–reducer” biocycle. To get a better insight into the cenosis-forming role of microalgae, a mathematical model of the “autotroph–heterotroph” aquatic biotic cycle has been constructed, taking into account the utilization of Chlorella photosynthates and dead cells by microorganisms and the contribution of the components to the nitrogen cycle. A theoretical study showed that the biomass of concomitant bacteria grown on glucose and detritus is larger than the biomass of bacteria utilizing only microalgal photosynthates, which agrees well with the experimental data.

Transfer Volume-Dependent Recovery of Salmonella from Minced Meat

Six hundred 25-g samples of ground beef were divided into 3 groups of 200 each and 1 drop of a Salmonella broth culture was added to each sample. After storage at −27°C for 3–4 months, the samples were defrosted and blended with 225 ml of buffered peptone water. Ten ml of each suspension was preenriched at 37°C for 20 h and 10-fold dilutions of the material were made. One ml each of the preenriched culture and dilutions of 10−2, 10−4, 10−6, and 10−8 were transferred to selective enrichment media, and subsequently streaked onto selective agar plates. The mean percentage of Salmonella-positives obtained from all combinations of the selective media in relation to undiluted preenriched material and its 10−2, 10−4, 10−6, and 10−8 dilutions were for Salmonella typhimurium 70, 81, 84, 37, and 2, for Salmonella choleraesuis 64, 78, 66, 30, and 2, and for Salmonella anatum 60, 84, 75, 40, and 1, respectively. Colonies originating from diluted samples, particularly 10−4 and further dilutions, usually represented pure cultures of salmonellae, but from undiluted material were frequently accompanied or outgrown by concomitant bacteria.

Inhibitory Effect of a Protease Inhibitor, Leupeptin, on the Development of Influenza Pneumonia, Mediated by Concomitant Bacteria

The protease inhibitor leupeptin prevented multiple step replication of an influenza virus (A/swine/1976/31, H1N1) mediated by staphylococcal proteases. It also suppressed virus replication and development of fatal pneumonia in mice co-infected with the virus and Staphylococcus aureus.

Changes in symbiotic and associative interrelations in a higher plant-bacterial system during space flight

The miniature cenosis consisting of the water fern Azolla with its associated symbiotic nitrogen-fixing cyanobacterium Anabaena and the concomitant bacteria was investigated. Ecological closure was shown to produce sharp quantitative and qualitative changes in the number and type of concomitant bacteria. Changes in the distribution of bacterial types grown on beef-extract broth after space flight were recorded. Anabaena azollae underwent the most significant changes under spaceflight conditions. Its cell number per Azolla biomass unit increased substantially. Thus closure of cenosis resulted in a weakening of control over microbial development by Azolla . This tendency was augmented by spaceflight factors. Reduction in control exerted by macro-organisms over development of associated micro-organisms must be taken into account in constructing closed ecological systems in the state of weightlessness.