Isolation and identification of adherent epimural bacteria during succession in young lambs

Successive changes in aerobic and anaerobic bacterial counts and changes in the generic composition of the epimural community in lambs from 1 to 10 weeks were determined. Bacterial culture counts revealed a predominantly anaerobic community, with the mean anaerobic count being 1.4 X 10(7) CFU/cm2 of tissue surface. The aerobic count was highest at 1 week of age and declined significantly thereafter to a mean of 1.8 X 10(4) CFU/cm2, thus representing only 0.13% of the mean anaerobic count after week 1. Of the 345 strains isolated anaerobically at 1, 2, 4, 6, 8, and 10 weeks of age, 47, 32, 12, 32, 2, and 5% were capable of growth in a partially reduced medium, indicating a reduction in the number of facultative anaerobes with time. The majority of isolated strains were identified as belonging to genera commonly isolated from rumen contents. In some instances, however, strains did not correspond to previously described species, and some genera were present in proportions different from those expected in rumen fluid. At three of the sampling times, one genus was dominant, constituting 45 to 55% of the isolates. These dominant isolates were Streptococcus bovis, Bacteroides sp., and an anaerobic Streptococcus sp. for weeks 1, 2, and 10, respectively. During the transition period (weeks 4 to 8), two or more groups were codominant.     

Colony counts and characterization of bacteria adherent to the rumen wall and desquamated epithelial cells in conventional young lambs

Characterization and enumeration of the adherent epimural community of the rumen wall of young, conventionally reared lambs were carried out from 2 to 21 days after birth. Three hundred strains were isolated by anaerobic procedures from three sites: dorsal, ventral, and caudal sacs, and from the sloughed epithelial cells. The population of epimural bacteria was very dense from the first days of the lamb's life. This population increased slightly with age. During the first week the counts were similar in the dorsal and ventral sacs, but they were 10 to 100 times lower in the caudal sac. Total counts for anaerobic bacteria were higher than the counts for aerobic bacteria. The isolated strains were distributed into 19 groups: 11 groups included aerotolerant strains, and 8 others, strictly anaerobic strains. During the first week the facultative microflora was mainly composed of Escherichia coli and Streptococci. Later, the epimural community was more complex and included Staphyloccus, Micrococcus, and Gaffkya. The strictly anaerobic microflora was mainly composed of Clostridium, Peptostreptococcus, Veillonella, Propionibacterium, and Acidaminococcus. Some of these strains appeared to be similar to those previously isolated from the rumen fluid of young lambs; however, the genera Micrococcus, Veillonella, Gaffkya, and Acidaminococcus, and E. coli seemed to be specific of the rumen wall tissues.     

Isolation and Presumptive Identification of Adherent Epithelial Bacteria (“Epimural” Bacteria) from the Ovine Rumen Wall

One hundred sixty-one strains of adherent bacteria were isolated under anaerobic conditions from four sites on the rumen epithelial surface of sheep fed hay or a hay-grain ration. Before isolation of bacteria, rumen tissue was washed six times in an anaerobic dilution solution, and viable bacteria suspended in the washings were counted. Calculation indicated that unattached bacteria would have been removed from the tissue by this procedure, but a slow and progressive release of attached bacteria also occurred. Nevertheless, a wide range of characteristic morphological types remained associated with the epithelium as demonstrated by scanning electron microscopy. Most of these types were represented among the isolates. Characterization and presumptive identification of the isolates showed that 95.0% belonged to previously described genera of functionally significant rumen bacteria, including Butyrivibrio sp. (31.1%), Bacteroides sp. (22.4%), Selenomonas ruminantium (9.9%), Succinivibrio dextrinosolvens (8.7%), Streptococcus bovis (8.1%), Propionibacterium sp. (4.3%), Treponema sp. (3.1%), and Eubacterium sp., Lachnospira multiparus, and Ruminococcus flavefaciens (2.5% each). Eight isolates (5.0%) were not identified. L. multiparus was recovered only from hay-fed animals; all other genera were obtained from animals fed either ration. All S. bovis strains and two strains each of Bacteroides sp. and Butyrivibrio sp. were aerotolerant; all other strains were strictly anaerobic. Bacteria representing the gram-positive, facultatively anaerobic flora associated with rumen wall tissue (R. J. Wallace, K.-J. Cheng, D. Dinsdale, and E. R. Ørskov, Nature (London) 279:424-426, 1979) were therefore not recovered by the techniques used; instead a different fraction of the adherent population was isolated. The term “epimural” is proposed to describe the flora associated with the rumen epithelium.     

Bacteria isolated from the duodenum, ileum, and cecum of young chicks.

Facultatively anaerobic and strictly anaerobic bacteria colonizing the intestinal tracts of 14-day-old chicks fed a corn-based diet were enumerated, isolated, and identified. Colony counts from anaerobic roll tubes (rumen fluid medium) or aerobic plates (brain heart infusion agar) recovered from homogenates of the duodenum, upper and lower ileum, and cecum varied appreciably among samples from individual birds. Anaerobic and aerobic counts from the duodenum and ileum were similar. Anaerobic counts were highest from the cecum (0.7 X 10(11) to 1.6 X 10(11)/g of dry tissue) and exceeded aerobic plate counts by a factor of at least 10(2). Facultatively anaerobic groups (Streptococcus, Staphylococcus, Lactobacillus, and Escherichia coli) comprised the predominant flora of the duodenum and ileum, although large numbers of anaerobes (9 to 39% of the small intestine isolates), represented by species of Eubacterium, Propionibacterium, Clostridium, Gemmiger, and Fusobacterium, were also recovered. Strict anaerobes (anaerobic gram-positive cocci, Eubacterium, Clostridium Gemmiger, Fusobacterium, and Bacteriodes) made up nearly the entire microbial population of the cecum. Scanning electron microscopy of the intestinal epithelia of chicks revealed populations of microbes on the duodenal, ileal, and cecal mucosal surfaces.     

Characterization of subterranean bacteria in the Hungarian Upper Permian Siltstone (Aleurolite) Formation

The main purpose of this work was to study the microbiology of the Hungarian Upper Permian Siltstone (Aleurolite) Formation, to assess the safety of future underground repositories for nuclear waste. Sixty-seven air, groundwater, technical water, rock, and surface samples were collected aseptically from different depths. The number of aerobic and anaerobic isolates was 277. The mesophilic minimum and maximum CFU counts of the air samples were 1.07-5.84 x 10(2).mL-1 (aerobic) and 0.22-1.04 x 10(2).mL-1 (anaerobic), respectively; those of the water samples were 0.39-1.25 x 10(5).mL-1 (aerobic) and 0.36-3.9 x 10(3).mL-1 (anaerobic); those of the technical water samples were 0.27-5.03 x 10(6).mL-1 (aerobic) and 4 x 10(5)-->10(6).mL-1 (anaerobic); and those of the aleurolite samples were 2.32 x 10(2)-2.47 x 10(5).g-1 (aerobic) and 0.45-9.5 x 10(2).g-1 (anaerobic). In the groundwater, the thermophilic aerobic bacteria count was 0-2.4 x 10(2).mL-1 and the thermophilic anaerobic bacteria count was 0.43-4.6 x 10(4).mL-1. The gases produced by the 16 gas-forming isolates were CO2 (aerobic isolates), and CO2 and H2 (anaerobic isolates). About 20% of the aerobic isolates produced siderophores. The proportions of organic acid producers were lowest in aerobic and anaerobic isolates from the aleurolite, 13% and 14%, respectively. The highest proportions of acid producers in the aerobic and anaerobic isolates from the air samples were 63% and 54%. Altogether 160 of the aerobic isolates and 52 of the anaerobic isolates were spore formers. The radiosensitivity of the aerobic isolates was also determined; the D10 values of the sporeformers ranged between 0.8-2.44 kGy. Our results indicate that the sulfate-reducing bacteria and the production of complexing agents (siderophores) may contribute to the mobilization of radionuclides from underground repositories. As well, microbial gas production can influence the environmental conditions. The variability in bacterial radiotolerance indicates the biodiversity at this potential disposal site. These facts must be considered during the planning of a nuclear waste repository.     

Identification and enumeration of oleic acid and linoleic acid hydrating bacteria in the rumen of sheep and cows

The diversity and population densities of facultative anaerobic bacteria with the capacity to hydrate oleic acid and linoleic acid in the rumen of sheep and dairy cows were determined. The screening of representative colonies, from rumen fluid plated aerobically on a range of agar media, revealed that sheep rumen fluid contained hydration-positive strains of Streptococcus, Staphylococcus, Enterococcus, Lactobacillus and Pediococcus, whereas cow rumen fluid contained hydration-positive strains of Streptococcus, Lactobacillus and Staphylococcus. Mean counts of facultative anaerobic bacteria in sheep and cattle rumen were log10 7.29 and log10 6.40, respectively, and were independent of diet. Approximately 56% of facultative anaerobic bacteria were able to hydrate oleic and/or linoleic acid in anaerobic broth culture. For both sheep and cows, the most numerous hydration-positive isolates were strains of Strep. bovis. The results, which are the first to show that pediococci have the capacity to hydrate unsaturated fatty acids, suggest that lactic acid bacteria are the major unsaturated fatty acid hydrating bacteria in the rumen.     

Heterotrophic bacteria present in hindguts of wood-eating termites [Reticulitermes flavipes (Kollar)]

Strict anaerobic culture techniques were used to quantitate heterotrophic bacteria present in hindguts of Reticulitermes flavipes. The grand mean number of viable cells per hindgut was 0.4 X 10(5) (first-instar larvae), 1.3 X 10(5) (third-instar larvae), 3.5 X 10(5) (workers), and 1.5 X 10(5) (soldiers). Of a total of 344 isolates, 66.3% were streptococci that were always obtained regardless of the origin of termites, their developmental stage or caste, or their length of captivity. Most of the remaining isolates were strains of Bacteroides and Enterobacteriaceae. A small percentage were strains of Lactobacillus, Fusobacterium, and unidentified anaerobic gram-positive rods. Recovery of bacteria from worker hindguts was 13.0% of the direct microscopic count. Isolations performed aerobically failed to reveal strict aerobes. Attempts to isolate cellulolytic bacteria were uniformly unsuccessful. Of 145 streptococcal strains isolated from freshly collected termites, almost all were Streptococcus lactis and S. cremoris. Enterobacteriaceae isolates from the same termite specimens were indole-positive Citrobacter, citrate-negative Citrobacter, and Enterobacter cloacae. The possibility of in situ interspecies lactate transfer, between lactate producers (e.g., streptococci) and lactate fermenters (Bacteroides), is discussed.     

Anaerobic bacteria detected in inflammatory conditions of the respiratory tract

In this study a participation of anaerobic bacteria in respiratory tract diseases is presented. Bronchial washings collected by ++fibrobronchoscope constituted material for the study. Immediately after collection the material was plated onto two media for aerobic bacteria (hemomedium) and anaerobic bacteria (anaeromedium). Then, the samples were centrifuged and a sediment was plated on solid media suitable for aerobic and anaerobic bacteria. Bacterial anaerobic isolates were identified by using API 20E and their sensitivity to antibiotics was tested. From the material described above the most frequently isolated anaerobic bacteria were such as: Streptococcus intermedius, Bacteroides melaninogenicus, Veilonella sp. Among aerobic bacteria the most frequently isolated were Gram-negative rods, Streptococcus faecalis, Branhamella catarrhalis. It is worth to underline that in about 25% of cases anaerobic bacteria were the only isolates.     

Isolation, Culture Characteristics, and Identification of Anaerobic Bacteria from the Chicken Cecum

Studies on the anaerobic cecal microflora of the 5-week-old chicken were made to determine a suitable roll-tube medium for enumeration and isolation of the bacterial population, to determine effects of medium components on recovery of total anaerobes, and to identify the predominant bacterial groups. The total number of microorganisms in cecal contents determined by direct microscope cell counts varied (among six samples) from 3.83 x 10(10) to 7.64 x 10(10) per g. Comparison of different nonselective media indicated that 60% of the direct microscope count could be recovered with a rumen fluid medium (M98-5) and 45% with medium 10. Deletion of rumen fluid from M98-5 reduced the total anaerobic count by half. Colony counts were lower if chicken cecal extract was substituted for rumen fluid in M98-5. Supplementing medium 10 with liver, chicken fecal, or cecal extracts improved recovery of anaerobes slightly. Prereduced blood agar media were inferior to M98-5. At least 11 groups of bacteria were isolated from high dilutions (10(-9)) of cecal material. Data on morphology and physiological and fermentation characteristics of 90% of the 298 isolated strains indicated that these bacteria represented species of anaerobic gram-negative cocci, facultatively anaerobic cocci and streptococci, Peptostreptococcus, Propionibacterium, Eubacterium, Bacteroides, and Clostridium. The growth of many of these strains was enhanced by rumen fluid, yeast extract, and cecal extract additions to basal media. These studies indicate that some of the more numerous anaerobic bacteria present in chicken cecal digesta can be isolated and cultured when media and methods that have been developed for ruminal bacteria are employed.     

Bacterial flora of the sea urchin Echinus esculentus.

A total of 85 isolates of mesophilic, aerobic, heterotrophic bacteria were isolated from the gut, peristomial membrane, and coelomic fluid from specimens of the sea urchin Echinus esculentus from the Clyde Sea area of Scotland. These isolates were compared with 26 isolates from sand and seawater in the same locality. Overall, strains of Pseudomonas and Vibrio predominated. Gut (with an average bacterial viable count of 2 X 10(7) per 3-cm section) and coelomic fluid (which was often sterile and rarely had more than 40 bacteria per ml) had similar distributions of genera, with Vibrio predominating and Pseudomonas and Aeromonas next in abundance. In contrast, the flora of the peristomial membrane (with an average count of detachable bacteria of 2.5 X 10(5) per membrane) resembled that of sand/seawater in having Pseudomonas predominating, gram-positive forms or Vibrio next in abundance, and smaller numbers of Aeromonas, Flavobacterium, Acinetobacter, and Moraxella.     

Antibiotic activity of an isocyanide metabolite of Trichoderma hamatum against rumen bacteria

A metabolite of Trichoderma hamatum, 3-(3-isocyanocyclopent-2-enylidene)propionic acid, was tested for its effects on growth of and carbohydrate metabolism in 11 strains of functionally important rumen bacteria. To standardize the biological activity of this unstable metabolite, a rapid, aerobic disc diffusion assay was developed using Escherichia coli ATCC 11775. In an anaerobic broth dilution assay using a medium lacking rumen fluid and containing a soluble carbohydrate, the minimum inhibitory concentration of the metabolite which completely inhibited growth of the rumen bacteria for 18 h at 39 degrees C was generally less than 10 micrograms X mL-1; however, the minimum inhibitory concentrations for Megasphaera elsdenii B159 and Streptococcus bovis Pe(1)8 were 10-25 and 25-64 micrograms X mL-1, respectively. In general, the Gram-negative strains were more sensitive than the Gram positive. The minimum inhibitory concentration for Bacteroides ruminicola 23 grown with glucose was 1 micrograms X mL-1; for B. ruminicola GA33 (glucose), B. succinogenes S85 (cellobiose), and Succinivibrio dextrinosolvens 24 (maltose), it was 2 microgram X mL-1. When added to a cellulose-containing rumen fluid medium, 1-4 micrograms X mL-1 of the metabolite delayed cellulose hydrolysis by B. succinogenes S85, Ruminococcus albus 7, and R. flavefaciens FD1 for up to 4 days, and 6-7 micrograms X mL-1 prevented hydrolysis for at least 1 month. In the presence of the metabolite, the proportion of acetate produced from soluble carbohydrate by the majority of strains increased, but with some strains net production of acetate decreased relative to production of other acidic fermentation products.(ABSTRACT TRUNCATED AT 250 WORDS)     

Control of Listeria spp. by competitive-exclusion bacteria in floor drains of a poultry processing plant

In previous studies workers determined that two lactic acid bacterium isolates, Lactococcus lactis subsp. lactis C-1-92 and Enterococcus durans 152 (competitive-exclusion bacteria [CE]), which were originally obtained from biofilms in floor drains, are bactericidal to Listeria monocytogenes or inhibit the growth of L. monocytogenes both in vitro and in biofilms at 4 to 37 degrees C. We evaluated the efficacy of these isolates for reducing Listeria spp. contamination of floor drains of a plant in which fresh poultry is processed. Baseline assays revealed that the mean numbers of Listeria sp. cells in floor drains sampled on six different dates (at approximately biweekly intervals) were 7.5 log(10) CFU/100 cm(2) for drain 8, 4.9 log(10) CFU/100 cm(2) for drain 3, 4.4 log(10) CFU/100 cm(2) for drain 2, 4.1 log(10) CFU/100 cm(2) for drain 4, 3.7 log(10) CFU/100 cm(2) for drain 1, and 3.6 log(10) CFU/100 cm(2) for drain 6. The drains were then treated with 10(7) CE/ml in an enzyme-foam-based cleaning agent four times in 1 week and twice a week for the following 3 weeks. In samples collected 1 week after CE treatments were applied Listeria sp. cells were not detectable (samples were negative as determined by selective enrichment culture) for drains 4 and 6 (reductions of 4.1 and 3.6 log(10) CFU/100 cm(2), respectively), and the mean numbers of Listeria sp. cells were 3.7 log(10) CFU/100 cm(2) for drain 8 (a reduction of 3.8 log(10) CFU/100 cm(2)), <1.7 log(10) CFU/100 cm(2) for drain 1 (detectable only by selective enrichment culture; a reduction of 3.3 log(10) CFU/100 cm(2)), and 2.6 log(10) CFU/100 cm(2) for drain 3 (a reduction of 2.3 log(10) CFU/100 cm(2)). However, the aerobic plate counts for samples collected from floor drains before, during, and after CE treatment remained approximately the same. The results indicate that application of the two CE can greatly reduce the number of Listeria sp. cells in floor drains at 3 to 26 degrees C in a facility in which fresh poultry is processed.     

老年人胃内菌群研究

目的研究人体胃内菌群,探讨老年与非老年人胃内菌群的差异。方法选择67例无严重胃肠道疾病的患者为研究对象。其中男性50例、女性17例。年龄≥60岁53例,〈60岁14例。胃镜下取胃组织及胃液,测胃液pH,并做胃组织需氧、厌氧细菌培养及真菌培养,计数胃组织细菌培养数量。16SrRNA法鉴定胃组织细菌种类。真菌的鉴定按微生物科常规菌种方法鉴定。结果老年人中胃内需氧细菌培养阳性为23例（48.93%）,12例（25.53%）胃内需氧菌培养〉1×10^5CFU/g;厌氧细菌培养阳性为22例（46.81%）,12例（25.53%）胃内厌氧菌培养〉1×10^5CFU/g。非老年人中需氧细菌培养阳性为4例（28.57%）,1例（7.14%）胃内需氧菌培养〉1×10^5CFU/g;厌氧细菌培养阳性为4例（28.57%）,1例（7.14%）胃内厌氧菌培养〉1×10^5CFU/g。但老年人与非老年人比较,细菌培养阳性率及细菌培养〉1×10^5CFU/g的比率差异无显著性。仅1例老年人胃组织分离出真菌,为白色念珠菌。胃内共分离出细菌69株,其中革兰阳性球菌31株（44.93%）,革兰阳性杆菌12株（17.39%）,革兰阴性球菌11株（15.94%）,革兰阴性杆菌15株（21.74%）。需氧菌13株（18.84%）,需氧兼性厌氧菌54株（78.26%）,专性厌氧菌2株（2.90%）。老年人胃内常见的细菌是：链球菌、大肠埃希菌、奈瑟菌;非老年人胃内常见的细菌是：链球菌和大肠埃希菌。多为口咽部和胃肠道常见菌群,部分为条件致病菌。结论约46%～48%的老年人胃内细菌培养阳性,约25%的老年人有胃内细菌过度生长（〉1×10^5CFU/g）。约28%的非老年人胃内细菌培养阳性,约7%的非老年人有胃内细菌过度生长。老年人胃内菌群分布与非老年人相似,为口咽部和胃肠道常见菌群,部分为条件致病菌。     

An in vitro time-kill assessment of linezolid and anaerobic bacteria

Linezolid is a novel oxazolidinone antibacterial agent active against staphylococci (including methicillin-resistant strains), enterococci (including vancomycin-resistant strains), streptococci (including penicillin-intermediate and -resistant Streptococcus pneumoniae), and other aerobic and facultative bacteria. The agent has also demonstrated activity against a broad spectrum of Gram-positive and Gram-negative anaerobic bacteria. Previous time-kill assessments have shown linezolid to be generally bacteriostatic against staphylococci and enterococci, and bactericidal against streptococci. In this study, an anaerobic glovebox technique was employed to conduct time-kill assessments for four strains of anaerobic Gram-positive, and seven strains of anaerobic Gram-negative bacteria. The time-kill experiment was performed using Anaerobe Broth medium. The drugs were tested at four-fold the minimum inhibitory concentration (MIC), or at the higher concentration of 8mg/L for linezolid, 2mg/L for clindamycin, and 8mg/L for metronidazole. Samples for viable count were taken at 0, 6, and 24h, and plated using the Bioscience International Autospiral DW. Exposure of samples to the aerobic environment during plating was held to less than 30min. Plates were counted after a 48h anaerobic incubation (37 degrees C). The species tested included Bacteroides fragilis (2), B. distasonis, B. thetaiotaomicron, Fusobacterium nucleatum, F. varium, Prevotella melaninogenica, Clostridium perfringens, Eubacterium lentum and Peptostreptococcus anaerobius (2). The activity of linezolid was compared to that of metronidazole and clindamycin, two standard anti-anaerobe agents. As expected, the control agents were very active in these assays. Metronidazole yielded log(10)CFU/mL reductions of 3.0 or greater for nine of ten strains; clindamycin yielded log(10)CFU/mL reductions of 2.0 or greater for six of 11 strains, and 3.0 or greater for three strains. Linezolid also produced significant in vitro killing in this model achieving log(10)CFU/mL reductions of 2.0 or greater for six of 11 strains, and 3.0 or greater for four strains. The profile of activity was similar to that of clindamycin indicating that additional developmental studies of linezolid with anaerobic bacteria are warranted.     

Effects of antimicrobial agents fed to chickens on some gram-negative enteric bacilli

Total and antimicrobial agent-resistant aerobic and facultative anaerobic gram-negative enteric bacilli in fecal samples of broiler chickens fed growth-promotional levels of antimicrobial agents were determined quantitatively. Two 8-week studies were conducted utilizing groups of chickens fed antimicrobial-supplemented rations; the second study involved feed "pasteurization" as a means of minimizing colonization from the feed. Dilution/spread-plating/replica-plating techniques on selective media were used to obtain counts of total organisms and those resistant to tetracycline, chloramphenicol, streptomycin, ampicillin, or kanamycin. The predominant aerobic and facultative anaerobic gram-negative organism was Escherichia coli, which was detected in all samples at levels ranging from 10(5) to over 10(10) CFU/g of feces. Less common were Proteus mirabilis, Klebsiella pneumoniae, and Pseudomonas sp., which varied in occurrence and levels from group to group (range, less than 10(3) to 10(8) CFU/g). Resistance to all antimicrobials (except chloramphenicol in E. coli) was commonly observed at incidences exceeding 10(3) CFU/g in the total populations. Colonization of the chickens' intestinal tracts by susceptible and resistant strains of E. coli, K. pneumoniae, and Pseudomonas sp. appeared to result from their presence in the environment of the newly hatched chickens. Ration pasteurization did affect P. mirabilis, which appeared to colonize from the feed. The results suggest that colonization by, and proliferation of, antimicrobial-resistant aerobic and facultative anaerobic gram-negative enteric bacilli in chicken intestinal tracts may be less dependent on selection through antimicrobial supplementation of the ration than on their prevalence in environments from which they can colonize newborns.     

Effects of antimicrobial agents fed to chickens on some gram-negative enteric bacilli.

Total and antimicrobial agent-resistant aerobic and facultative anaerobic gram-negative enteric bacilli in fecal samples of broiler chickens fed growth-promotional levels of antimicrobial agents were determined quantitatively. Two 8-week studies were conducted utilizing groups of chickens fed antimicrobial-supplemented rations; the second study involved feed "pasteurization" as a means of minimizing colonization from the feed. Dilution/spread-plating/replica-plating techniques on selective media were used to obtain counts of total organisms and those resistant to tetracycline, chloramphenicol, streptomycin, ampicillin, or kanamycin. The predominant aerobic and facultative anaerobic gram-negative organism was Escherichia coli, which was detected in all samples at levels ranging from 10(5) to over 10(10) CFU/g of feces. Less common were Proteus mirabilis, Klebsiella pneumoniae, and Pseudomonas sp., which varied in occurrence and levels from group to group (range, less than 10(3) to 10(8) CFU/g). Resistance to all antimicrobials (except chloramphenicol in E. coli) was commonly observed at incidences exceeding 10(3) CFU/g in the total populations. Colonization of the chickens' intestinal tracts by susceptible and resistant strains of E. coli, K. pneumoniae, and Pseudomonas sp. appeared to result from their presence in the environment of the newly hatched chickens. Ration pasteurization did affect P. mirabilis, which appeared to colonize from the feed. The results suggest that colonization by, and proliferation of, antimicrobial-resistant aerobic and facultative anaerobic gram-negative enteric bacilli in chicken intestinal tracts may be less dependent on selection through antimicrobial supplementation of the ration than on their prevalence in environments from which they can colonize newborns.     

Biotransformation of polycyclic aromatic hydrocarbons by yeasts isolated from coastal sediments.

Yeast abundance in the sediments of 13 coastal sites in Massachusetts was quantified, and the potential of yeast isolates to biotransform polycyclic aromatic hydrocarbons (PAHs) was determined. Plate counts of yeasts varied between 10(2) to 10(7) CFU g (dry weight) of sediment-1. The most abundant genera isolated and identified included Candida, Cryptococcus, Rhodotorula, Torulopsis, and Trichosporon. More than 50% of the isolates from heavily contaminated sites transformed phenanthrene, as determined by spray-plate screening. The plate counts of phenanthrene-transforming yeasts correlated significantly to the sediment concentrations of phenanthrene. Transformation of [9-14C]phenanthrene and [12-14C]benz[a]anthracene by individual isolates varied greatly, ranging from 0.15 to 8.15 mumol of PAH g-1 in 120-h incubations. Of the isolated yeasts, Trichosporon penicillatum exhibited the greatest capacity for phenanthrene transformation. The ability to transform PAHs appears to be widespread among yeasts in coastal sediments.     

Streptococci species of anginosus group isolated from oral and maxillofacial infections

The aim of the study was to isolate and identify at species level streptococci strains of anginosus group in pus samples collected from 110 patients with oral and maxillofacial (OMF) infections. Gram-stained smears and cultures on selective and nonselective media were done from each of the 111 pus samples (2 samples were collected from one of the patients, who presented 2 oral abscesses at the same time). The isolates were identified on the basis of cultural and biochemical characteristics. Speciation of the anginosus group isolates was performed using the Rapid ID 32 Strep system (Bio Mérieux, France). Fourty-four anginosus group strains were isolated from 42 patients. Fourty of these isolates were identified as Streptococcus anginosus (2 nonidentical isolates were found in 2 patients), 3 isolates as Streptococcus constellatus and only one as Streptococcus intermedius. The study confirmed that the anginosus group is often involved in OMF infections alone or in association with other aerobic and/or anaerobic bacteria. In the investigated cases, Streptococcus anginosus was by far the most frequently isolated species within the anginosus group.     

Isolation and identification of rumen bacteria capable of anaerobic phloroglucinol degradation.

Eight strains of rumen bacteria capable of degrading phloroglucinol (1,3,5-trihydroxybenzene) under anaerobic conditions were isolated from enrichment cultures of the bovine rumen microflora established in a prereduced medium containing 0.02 M phloroglucinol. Five of the strains were facultatively anaerobic Gram-positive streptococci which were identified as Streptococcus bovis. Three strains of obligately anaerobic Gram-positive cocci were assigned to the genus Coprococcus. Anaerobic cultures of the Streptococcus bovis strains in a 40% rumen fluid medium initially containing 0.02 M phloroglucinol degraded 50-80% of the substrate within 2 days, whereas cultures of the Coprococcus strains degraded more than 80% of the substrate under the same conditions. The Streptococcus bovis strains were incapable of degrading phloroglucinol in brain heart infusion or in the medium of de Man, Rogosa, and Sharpe (MRS broth) incubated aerobically.